US20170288078A1 - Interconnect assembly - Google Patents
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- US20170288078A1 US20170288078A1 US15/473,476 US201715473476A US2017288078A1 US 20170288078 A1 US20170288078 A1 US 20170288078A1 US 201715473476 A US201715473476 A US 201715473476A US 2017288078 A1 US2017288078 A1 US 2017288078A1
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/02002—Arrangements for conducting electric current to or from the device in operations
- H01L31/02005—Arrangements for conducting electric current to or from the device in operations for device characterised by at least one potential jump barrier or surface barrier
- H01L31/02008—Arrangements for conducting electric current to or from the device in operations for device characterised by at least one potential jump barrier or surface barrier for solar cells or solar cell modules
- H01L31/0201—Arrangements for conducting electric current to or from the device in operations for device characterised by at least one potential jump barrier or surface barrier for solar cells or solar cell modules comprising specially adapted module bus-bar structures
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
- H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/0445—PV modules or arrays of single PV cells including thin film solar cells, e.g. single thin film a-Si, CIS or CdTe solar cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
- H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
- H01L31/0512—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module made of a particular material or composition of materials
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Definitions
- Embodiments of the present invention relate generally to the field of photovoltaic technology.
- solar-cell modules fabricated from arrays of such thin-film solar cells are also impacted by parasitic series resistances.
- a significant challenge is the development of solar-cell, current collection and interconnection schemes that minimize the effects of such parasitic resistances.
- the reliability of solar-cell modules based on such schemes is equally important as it determines the useful life of the solar-cell module and therefore its cost effectiveness and viability as a reliable alternative source of energy.
- Embodiments of the present invention include an interconnect assembly.
- the interconnect assembly includes a trace that includes a plurality of electrically conductive portions.
- the plurality of electrically conductive portions is configured both to collect current from a first solar cell and to interconnect electrically to a second solar cell.
- the plurality of electrically conductive portions is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired.
- FIG. 1A is a cross-sectional elevation view of a layer structure of a solar cell, in accordance with an embodiment of the present invention.
- FIG. 1B is a schematic diagram of a model circuit of a solar cell, electrically connected to a load, in accordance with an embodiment of the present invention.
- FIG. 2 is a schematic diagram of a model circuit of a solar-cell module, electrically connected to a load, that shows the interconnection of solar cells in the solar-cell module, in accordance with an embodiment of the present invention.
- FIG. 3 is a schematic diagram of a model circuit of a solar-cell module, electrically connected to a load, that details model circuits of interconnect assemblies, in accordance with an embodiment of the present invention.
- FIG. 4A is a schematic diagram of a model circuit of an interconnect assembly for connecting two solar cells of a solar-cell module, in accordance with an embodiment of the present invention.
- FIG. 4B is a plan view of the interconnect assembly of FIG. 4A that shows the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention.
- FIG. 4C is a cross-sectional, elevation view of the interconnect assembly of FIG. 4B that shows the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention.
- FIG. 4D is a cross-sectional, elevation view of an alternative interconnect assembly for FIG. 4B that shows an edge-conforming interconnect assembly for the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention.
- FIG. 4E is a cross-sectional, elevation view of an alternative interconnect assembly for FIG. 4B that shows a shingled-solar-cell arrangement for the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention.
- FIG. 4F is a plan view of an alternative interconnect assembly for FIG. 4A that shows the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention.
- FIG. 4G is a plan view of the interconnect assembly of FIG. 4A that shows the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention.
- FIG. 4H is a cross-sectional, elevation view of the interconnect assembly of FIG. 4G that shows the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention.
- FIG. 5A is a plan view of the combined applicable carrier film, interconnect assembly that shows the physical arrangement of a trace with respect to a top carrier film and a bottom carrier film in the combined applicable carrier film, interconnect assembly, in accordance with an embodiment of the present invention.
- FIG. 5B is a plan view of the combined applicable carrier film, interconnect assembly that shows the physical arrangement of a trace with respect to a top carrier film and a bottom carrier film in the combined applicable carrier film, interconnect assembly, in accordance with another embodiment of the present invention.
- FIG. 5C is a cross-sectional schematic view of the physical arrangement of elements of an interconnect assembly connecting two solar cells in accordance with an embodiment of the present invention such as described and illustrated with reference to FIG. 5B .
- FIG. 5D is a cross-sectional, elevation view of the combined applicable carrier film, interconnect assembly of FIG. 5A or 5B that shows the physical arrangement of a trace with respect to a top carrier film in the combined applicable carrier film, interconnect assembly prior to disposition on a solar cell, in accordance with embodiments of the present invention.
- FIG. 5E is a cross-sectional, elevation view of the interconnect assembly of FIG. 5D that shows the physical arrangement of a trace with respect to a top carrier film in the combined applicable carrier film, interconnect assembly after disposition on a solar cell, in accordance with an embodiment of the present invention.
- FIG. 6A is a plan view of an integrated busbar-solar-cell-current collector that shows the physical interconnection of a terminating solar cell with a terminating busbar in the integrated busbar-solar-cell-current collector, in accordance with an embodiment of the present invention.
- FIG. 6B is a cross-sectional, elevation view of the integrated busbar-solar-cell-current collector of FIG. 6A that shows the physical interconnection of the terminating solar cell with the terminating busbar in the integrated busbar-solar-cell-current collector, in accordance with an embodiment of the present invention.
- FIG. 7A is a combined cross-sectional elevation and perspective view of a roll-to-roll, interconnect-assembly fabricator for fabricating the interconnect assembly from a first roll of top carrier film and from a dispenser of conductive-trace material, in accordance with an embodiment of the present invention.
- FIG. 7B is a combined cross-sectional elevation and perspective view of a roll-to-roll, laminated-interconnect-assembly for fabricating a laminated-interconnect assembly from the first roll of top carrier film, from a second roll of bottom carrier film and from the dispenser of conductive-trace material, in accordance with an embodiment of the present invention.
- FIG. 8 is flow chart illustrating a method for roll-to-roll fabrication of an interconnect assembly, in accordance with an embodiment of the present invention.
- FIG. 9 is flow chart illustrating a method for interconnecting two solar cells, in accordance with an embodiment of the present invention.
- a cross-sectional elevation view of a layer structure of a solar cell 100 A is shown.
- the solar cell 100 A includes a metallic substrate 104 .
- an absorber layer 112 is disposed on the metallic substrate 104 ; the absorber layer 112 may include a layer of the material copper indium gallium diselenide (CIGS) having the chemical formula Cu(In 1-x Ga x )Se 2 , where x may be a decimal less than one but greater than zero that determines the relative amounts of the constituents, indium, In, and gallium, Ga.
- CGS copper indium gallium diselenide
- semiconductors having the chalcopyrite crystal structure for example, chemically homologous compounds with the compound CIGS having the chalcopyrite crystal structure, in which alternative elemental constituents are substituted for Cu, In, Ga, and/or Se, may be used as the absorber layer 112 .
- semiconductors such as silicon and cadmium telluride, as well as other semiconductors, may be used as the absorber layer 112 .
- the absorber layer 112 includes a p-type portion 112 a and an n-type portion 112 b .
- a pn homojunction 112 c is produced in the absorber layer 112 that serves to separate charge carriers that are created by light incident on the absorber layer 112 .
- the composition of the p-type portion 112 a of the absorber layer 112 may vary with depth to produce a graded band gap of the absorber layer 112 .
- the absorber layer 112 may include only a p-type chalcopyrite semiconductor layer, such as a CIGS material layer, and a pn heterojunction may be produced between the absorber layer 112 and an n-type layer, such as a metal oxide, metal sulfide or metal selenide, disposed on its top surface in place of the n-type portion 112 b shown in FIG. 1A .
- n-type layer such as a metal oxide, metal sulfide or metal selenide
- embodiments of the present invention are not limited to pn junctions fabricated in the manner described above, but rather a generic pn junction produced either as a homojunction in a single semiconductor material, or alternatively a heterojunction between two different semiconductor materials, is within the spirit and scope of embodiments of the present invention.
- semiconductors such as silicon and cadmium telluride, as well as other semiconductors, may be used as the absorber layer 112 .
- one or more transparent electrically conductive oxide (TCO) layers 116 are disposed, for example, to provide a means for collection of current from the absorber layer 112 for conduction to an external load.
- TCO transparent electrically conductive oxide
- the TCO layer 116 may include zinc oxide, ZnO, or alternatively a doped conductive oxide, such as aluminum zinc oxide (AZO), Al x Zn 1-x O y , and indium tin oxide (ITO), In x Sn 1-x O y , where the subscripts x and y indicate that the relative amount of the constituents may be varied.
- AZO aluminum zinc oxide
- ITO indium tin oxide
- the TCO layer 116 may be composed of a plurality of conductive oxide layers. These TCO layer materials may be sputtered directly from an oxide target, or alternatively the TCO layer may be reactively sputtered in an oxygen atmosphere from a metallic target, such as zinc, Zn, Al—Zn alloy, or In—Sn alloy targets.
- a metallic target such as zinc, Zn, Al—Zn alloy, or In—Sn alloy targets.
- the zinc oxide may be deposited on the absorber layer 112 by sputtering from a zinc-oxide-containing target; alternatively, the zinc oxide may be deposited from a zinc-containing target in a reactive oxygen atmosphere in a reactive-sputtering process.
- the reactive-sputtering process may provide a means for doping the absorber layer 112 with an n-type dopant, such as zinc, Zn, or indium, In, to create a thin n-type portion 112 b , if the partial pressure of oxygen is initially reduced during the initial stages of sputtering a metallic target, such as zinc, Zn, or indium, In, and the layer structure of the solar cell 100 A is subsequently annealed to allow interdiffusion of the zinc, Zn, or indium, In, with CIGS material used as the absorber layer 112 .
- an n-type dopant such as zinc, Zn, or indium, In
- sputtering a compound target such as a metal oxide, metal sulfide or metal selenide, may also be used to provide the n-type layer, as described above, on the p-type portion 112 a of the absorber layer 112 .
- a conductive backing layer 108 may be disposed between the absorber layer 112 and the metallic substrate 104 to provide a diffusion barrier between the absorber layer 112 and the metallic substrate 104 .
- the conductive backing layer 108 may include molybdenum, Mo, or other suitable metallic layer having a low propensity for interdiffusion with an absorber layer 112 , such as one composed of CIGS material, as well as a low diffusion coefficient for constituents of the substrate.
- the conductive backing layer 108 may provide other functions in addition to, or independent of, the diffusion-barrier function, for example, a light-reflecting function, for example, as a light-reflecting layer, to enhance the efficiency of the solar cell, as well as other functions.
- a light-reflecting function for example, as a light-reflecting layer
- the embodiments recited above for the conductive backing layer 108 should not be construed as limiting the function of the conductive backing layer 108 to only those recited, as other functions of the conductive backing layer 108 are within the spirit and scope of embodiments of the present invention, as well.
- FIG. 1B a schematic diagram of a model circuit 100 B of a solar cell that is electrically connected to a load is shown.
- the model circuit 100 B of the solar cell includes a current source 158 that generates a photocurrent, i L .
- the current source 158 is such as to produce counterclockwise electrical current, or equivalently an clockwise electron-flow, flowing around each of the loops of the circuit shown; embodiments of the present invention also apply, without limitation thereto, to solar-cell circuits in which the electrical current flows in a clockwise direction, or equivalently electrons flow in a counterclockwise direction.
- the photocurrent, i L is produced when a plurality of incident photons, light particles, of which one example photon 154 with energy, h ⁇ , is shown, produce electron-hole pairs in the absorber layer 112 and these electron-hole pairs are separated by the pn homojunction 112 c , or in the alternative, by a pn heterojunction as described above. It should be appreciated that the energy, h ⁇ , of each incident photon of the plurality of photons should exceed the band-gap energy, E g , that separates the valence band from the conduction band of the absorber layer 112 to produce such electron-hole pairs, which result in the photocurrent, i L .
- the model circuit 100 B of the solar cell further includes a diode 162 , which corresponds to recombination currents, primarily at the pn homojunction 112 c , that are shunted away from the connected load.
- the diode is shown having a polarity consistent with electrical current flowing counterclockwise, or equivalently electron-flow clockwise, around the loops of the circuit shown; embodiments of the present invention apply, without limitation thereto, to a solar cell in which the diode of the model circuit has the opposite polarity in which electrical current flows clockwise, or equivalently electron-flow flows counterclockwise, around the loops of the circuit shown.
- the model circuit 100 B of the solar cell includes two parasitic resistances corresponding to a shunt resistor 166 with shunt resistance, R Sh , and to a series resistor 170 with series resistance, R S .
- the solar cell may be connected to a load represented by a load resistor 180 with load resistance, R L .
- the circuit elements of the solar cell include the current source 158 , the diode 162 and the shunt resistor 166 connected across the current source 158 , and the series resistor 170 connected in series with the load resistor 180 across the current source 158 , as shown.
- the shunt resistor 166 like the diode 162 , are connected across the current source 158 , these two circuit elements are associated with internal electrical currents within the solar cell shunted away from useful application to the load.
- the series resistor 170 connected in series with the load resistor 180 are connected across the current source 158 , the series resistor 170 is associated with internal resistance of the solar cell that limits the electrical current to the load.
- the shunt resistance may be associated with surface leakage currents that follow paths at free surfaces that cross the pn homojunction 112 c ; free surfaces are usually found at the edges of the solar cell along the side walls of the device that define its lateral dimensions; such free surfaces may also be found at discontinuities in the absorber layer 112 that extend past the pn homojunction 112 c .
- the shunt resistance may also be associated with shunt defects which may be present that shunt electrical current away from the load. A small value of the shunt resistance, R Sh , is undesirable as it lowers the open circuit voltage, V OC , of the solar cell, which directly affects the efficiency of the solar cell.
- the series resistance, R S is associated with: the contact resistance between the p-type portion 112 a and the conductive backing layer 108 , the bulk resistance of the p-type portion 112 a , the bulk resistance of the n-type portion 112 b , the contact resistance between the n-type portion 112 b and TCO layer 116 , and other components, such as conductive leads, and connections in series with the load.
- These latter sources of series resistance, conductive leads, and connections in series with the load are germane to embodiments of the present invention as interconnect assemblies, which is subsequently described.
- a large value of the series resistance, R S is undesirable as it lowers the short circuit current, I SC , of the solar cell, which also directly affects the efficiency of the solar cell.
- FIG. 2 a schematic diagram of a model circuit 200 of a solar-cell module 204 that is coupled to a load is shown.
- the load is represented by a load resistor 208 with load resistance, R L , as shown.
- the solar-cell module 204 of the model circuit 200 includes a plurality of solar cells: a first solar cell 210 including a current source 210 a that generates a photocurrent, i L1 , produced by example photon 214 with energy, h ⁇ 1 , a diode 210 b and a shunt resistor 210 c with shunt resistance, R Sh1 ; a second solar cell 230 including a current source 230 a that generates a photocurrent, i L2 , produced by example photon 234 with energy, h ⁇ 2 , a diode 230 b and a shunt resistor 230 c with shunt resistance, R Sh2 ; and, a terminating solar cell 260 including a current source 260 a that generates a photocurrent, i L3 , produced by example photon 264 with energy, h ⁇ n , a diode 260 b and a shunt resistor 260 c with shunt resistance,
- the current sources are such as to produce counterclockwise electrical current, or equivalently an clockwise electron-flow, flowing around each of the loops of the circuit shown; embodiments of the present invention also apply, without limitation thereto, to solar-cell circuits in which the electrical current flows in a clockwise direction, or equivalently electrons flow in a counterclockwise direction.
- FIGS. 2 and 3 show that the current sources are such as to produce counterclockwise electrical current, or equivalently an clockwise electron-flow, flowing around each of the loops of the circuit shown; embodiments of the present invention also apply, without limitation thereto, to solar-cell circuits in which the electrical current flows in a clockwise direction, or equivalently electrons flow in a counterclockwise direction.
- the diode is shown having a polarity consistent with electrical current flowing counterclockwise, or equivalently electron-flow clockwise, around the loops of the circuit shown; embodiments of the present invention apply, without limitation thereto, to a solar cell in which the diode of the model circuit has the opposite polarity in which electrical current flows clockwise, or equivalently electron-flow flows counterclockwise, around the loops of the circuit shown.
- the series resistors with series resistances R S1 and R S2 correspond to interconnect assemblies 220 and 240 , respectively.
- Series resistor with series resistance, R S1 corresponding to interconnect assembly 220 is shown configured both to collect current from the first solar cell 210 and to interconnect electrically to the second solar cell 230 .
- Series resistor with series resistance, R Sn corresponds to an integrated solar-cell, current collector 270 .
- the ellipsis 250 indicates additional solar cells and interconnect assemblies (not shown) coupled in alternating pairs in series in model circuit 200 that make up the solar-cell module 204 .
- the series resistor with resistance R Sn , corresponding to the integrated solar-cell, current collector 270 , and R B2 , corresponding to the terminating busbar 280 in combination correspond to a integrated busbar-solar-cell-current collector 290 coupling the terminating solar cell 260 with the load resistor 208 .
- series resistor with resistance R S1 , corresponding to interconnect assembly 220 , and first solar cell 210 in combination correspond to a combined solar-cell, interconnect assembly 294 .
- to collect current refers to collecting, transferring, and/or transmitting current carriers of either sign, whether they be positively charged holes or negatively charged electrons; for the structures shown in FIGS. 1A-B , 2 , 3 , 4 A-F, 5 A-C and 6 A-B, in which an interconnect assembly is disposed above and electrically coupled to an n-type portion of the solar cell, the current carriers collected under normal operating conditions are negatively charged electrons.
- embodiments of the present invention apply, without limitation thereto, to solar cell configurations where a p-type layer is disposed on an n-type absorber layer, in which case the current carriers collected may be positively charged holes, as would be the case for solar cells modeled by diodes and current sources of opposite polarity to those of FIGS. 1A-B , 2 , 3 , 4 A-F, 5 A-C and 6 A-B.
- a current collector and associated interconnect assembly that collects current may, without limitation thereto, collect, transfer, and/or transmit charges associated with an electrical current, and/or charges associated with an electron-flow, as for either polarity of the diodes and current sources described herein, and thus for either configuration of a solar cell with an n-type layer disposed on and electrically coupled to a p-type absorber layer or a p-type layer disposed on and electrically coupled to an n-type absorber layer, as well as other solar cell configurations.
- the series resistances of the interconnect assemblies 220 and 240 , integrated solar-cell, current collector 270 , and the interconnect assemblies included in ellipsis 250 can have a substantial net series resistance in the model circuit 200 of the solar-cell module 204 , unless the series resistances of the interconnect assemblies 220 and 240 , integrated solar-cell, current collector 270 , and the interconnect assemblies included in ellipsis 250 are made small.
- Embodiments of the present invention provide for diminishing the series resistances of the interconnect assemblies 220 and 240 , integrated solar-cell, current collector 270 , and the interconnect assemblies included in ellipsis 250 .
- FIG. 3 a schematic diagram of a model circuit 300 of a solar-cell module 304 is shown that illustrates embodiments of the present invention such that the series resistances of the interconnect assemblies 320 and 340 , integrated solar-cell, current collector 370 , and the interconnect assemblies included in ellipsis 350 are made small.
- the solar-cell module 304 is coupled to a load represented by a load resistor 308 with load resistance, R L , as shown.
- the solar-cell module 304 of the model circuit 300 includes a plurality of solar cells: a first solar cell 310 including a current source 310 a that generates a photocurrent, i L1 , produced by example photon 314 with energy, h ⁇ 1 , a diode 310 b and a shunt resistor 310 c with shunt resistance, R Sh1 ; a second solar cell 330 including a current source 330 a that generates a photocurrent, i L2 , produced by example photon 334 with energy, h ⁇ 2 , a diode 330 b and a shunt resistor 330 c with shunt resistance, R Sh2 ; and, a terminating solar cell 360 including a current source 360 a that generates a photocurrent, i L3 , produced by example photon 364 with energy, h ⁇ n , a diode 360 b and a shunt resistor 360 c with shunt resistance, R Shn
- the interconnect assemblies 320 and 340 and the integrated solar-cell, current collector 370 , with respective equivalent series resistances R S1 , R S2 and R Sn are shown disposed in the solar-cell module 304 of the model circuit 300 connected in series with the solar cells 310 , 330 and 360 and the load resistor 308 .
- the ellipsis 350 indicates additional solar cells and interconnect assemblies (not shown) coupled in alternating pairs in series in model circuit 300 that make up the solar-cell module 304 .
- the integrated solar-cell, current collector 370 with resistance R Sn , and the series resistor with series resistance R B2 , corresponding to the terminating busbar 380 in combination correspond to an integrated busbar-solar-cell-current collector 390 coupling the terminating solar cell 360 with the load resistor 308 .
- interconnect assembly 320 with resistance, R S2 , and solar cell 310 in combination correspond to a combined solar-cell, interconnect assembly 394 .
- the interconnect assembly 320 includes a trace including a plurality of electrically conductive portions, identified with resistors 320 a , 320 b , 320 c , and 320 m with respective resistances, r P11 , r P12 , r P13 and r P1m , and the ellipsis 320 i indicating additional resistors (not shown).
- the plurality of electrically conductive portions of the trace are modeled here as discrete resistors the interconnection with solar cell 330 is considerably more complicated involving the distributed resistance in the TCO layer of the solar cell, which has been omitted for the sake of elucidating functional features of embodiments of the present invention. Therefore, it should be understood that embodiments of the present invention may also include, without limitation thereto, the effects of such distributed resistances on the trace.
- the plurality of electrically conductive portions, without limitation thereto, identified with resistors 320 a , 320 b , 320 c , 320 i , and 320 m are configured both to collect current from the first solar cell 310 and to interconnect electrically to the second solar cell 330 .
- the plurality of electrically conductive portions are configured such that upon interconnecting the first solar cell 310 and the second solar cell 330 the plurality of electrically conductive portions are connected electrically in parallel between the first solar cell 310 and the second solar cell 330 .
- the plurality of electrically conductive portions is configured such that equivalent series resistance, R S1 , of the interconnect assembly 320 including the parallel network of resistors 320 a , 320 b , 320 c , 320 i , and 320 m , is less than the resistance of any one resistor in the parallel network. Therefore, upon interconnecting the first solar cell 310 with the second solar cell 330 , the equivalent series resistance, R S1 , of the interconnect assembly 320 , is given approximately, omitting the effects of distributed resistances at the interconnects with the first and second solar cells 310 and 330 , by the formula for a plurality of resistors connected electrically in parallel, viz.
- the configuration of the plurality of electrically conductive portions due to this parallel arrangement of electrically conductive portions between the first solar cell 310 and the second solar cell 330 provides a redundancy of electrical current carrying capacity between interconnected solar cells should one of the plurality of electrically conductive portions become damaged, or its reliability become impaired.
- the plurality of electrically conductive portions is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired, because the loss of electrical current through any one electrically conductive portion will be compensated for by the plurality of other parallel electrically conductive portions coupling the first solar cell 310 with the second solar cell 330 .
- substantially undiminished with respect to solar-cell efficiency means that the solar-cell efficiency is not reduced below an acceptable level of productive performance.
- the interconnect assembly 340 includes a trace including a plurality of electrically conductive portions identified with resistors 340 a , 340 b , 340 c , and 340 m with respective resistances, r P21 , r P22 , r P23 and r P2m , and the ellipsis 340 i indicating additional resistors (not shown).
- the plurality of electrically conductive portions are configured both to collect current from a first solar cell 330 and to interconnect electrically to a second solar cell, in this case a next adjacent one of the plurality of solar cells represented by ellipsis 350 .
- a first solar cell and a second solar cell refer, without limitation thereto, to just two adjacent solar cells configured in series in the solar-cell module, and need not be limited to a solar cell located first in line of a series of solar cells in a solar-cell module, nor a solar cell located second in line of a series of solar cells in a solar-cell module.
- the resistors 340 a , 340 b , 340 c , 340 i , and 340 m are configured such that upon interconnecting the first solar cell 330 and the second solar cell, in this case the next adjacent solar cell of the plurality of solar cells represented by ellipsis 350 , the resistors 340 a , 340 b , 340 c , 340 i , and 340 m , are coupled electrically in parallel between the first solar cell 330 and the second solar cell, the next adjacent solar cell of the plurality of solar cells represented by ellipsis 350 .
- the plurality of electrically conductive portions is configured such that series resistance, R S2 , of the interconnect assembly 340 including the parallel network of resistors 340 a , 340 b , 340 c , 340 i , and 340 m , is less than the resistance of any one resistor in the network.
- the series resistance, R S2 , of the interconnect assembly 340 can be reduced lowering the effective series resistance between solar cells in the solar-cell module improving the solar-cell-module efficiency of the solar-cell module 304 .
- the plurality of electrically conductive portions may be configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired.
- the combined solar-cell, interconnect assembly 394 includes the first solar cell 310 and the interconnect assembly 320 ; the interconnect assembly 320 includes a trace disposed above a light-facing side of the first solar cell 310 , the trace further including a plurality of electrically conductive portions, identified with resistors 320 a , 320 b , 320 c , and 320 m with respective resistances, r P21 , r P22 , r P23 and r P2m , and the ellipsis 320 i indicating additional resistors (not shown).
- All electrically conductive portions of the plurality of electrically conductive portions are configured to collect current from the first solar cell 310 and to interconnect electrically to the second solar cell 330 .
- the plurality of electrically conductive portions identified with resistors 320 a , 320 b , 320 c , 320 i , and 320 m , may be configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired.
- any of the plurality of electrically conductive portions may be configured to interconnect electrically to the second solar cell 330 .
- the integrated busbar-solar-cell-current collector 390 includes the terminating busbar 380 and the integrated solar-cell, current collector 370 .
- the integrated solar-cell, current collector 370 includes a trace including a plurality of electrically conductive portions, identified with resistors 370 a , 370 b , 370 l , and 370 m with respective resistances, r Pn1 , r Pn2 , r Pnl and r Pnm , and the ellipsis 370 i indicating additional resistors (not shown).
- the plurality of electrically conductive portions are configured both to collect current from the first solar cell 310 and to interconnect electrically to the terminating busbar 380 .
- the resistors 370 a , 370 b , 370 i , 370 l and 370 m are coupled electrically in parallel between the terminating solar cell 360 and the terminating busbar 380 series resistor with series resistance, R B2 .
- the plurality of electrically conductive portions is configured such that series resistance, R Sn , of the interconnect assembly 340 including the parallel network of resistors 370 a , 370 b , 370 i , 370 l and 370 m , is less than the resistance of any one resistor in the network.
- the integrated solar-cell, current collector 370 includes a plurality of integrated pairs of electrically conductive, electrically parallel trace portions.
- Resistors 370 a , 370 b , 370 l and 370 m with respective resistances, r Pn1 , r Pn2 , r Pnl and r Pnm , and the ellipsis 370 i indicating additional resistors (not shown) form such a plurality of integrated pairs of electrically conductive, electrically parallel trace portions when suitably paired as adjacent pair units connected electrically together as an integral unit over the terminating solar cell 360 .
- one such pair of the plurality of integrated pairs of electrically conductive, electrically parallel trace portions is pair of resistors 370 a and 370 b connected electrically together as an integral unit over the terminating solar cell 360 , as shown.
- the plurality of integrated pairs of electrically conductive, electrically parallel trace portions are configured both to collect current from the terminating solar cell 360 and to interconnect electrically to the terminating busbar 380 .
- the plurality of integrated pairs of electrically conductive, electrically parallel trace portions is configured such that solar-cell efficiency is substantially undiminished in an event that any one electrically conductive, electrically parallel trace portion, for example, either one, but not both, of the resistors 370 a and 370 b of the integral pair, of the plurality of integrated pairs of electrically conductive, electrically parallel trace portions is conductively impaired.
- the solar-cell module 304 includes the first solar cell 310 , at least the second solar cell 330 and the interconnect assembly 320 disposed above a light-facing side of an absorber layer of the first solar cell 310 .
- the interconnect assembly 320 includes a trace comprising a plurality of electrically conductive portions, identified with resistors 320 a , 320 b , 320 c , and 320 m with respective resistances, r P11 , r P12 , r P13 and r P1m , and the ellipsis 320 i indicating additional resistors (not shown).
- the plurality of electrically conductive portions is configured both to collect current from the first solar cell 310 and to interconnect electrically to the second solar cell 330 .
- the plurality of electrically conductive portions is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired.
- FIGS. 4A, 4B and 4C a schematic diagram of a model circuit 400 A of an interconnect assembly 420 connecting a first solar cell 410 to a second solar cell 430 of a solar-cell module 404 is shown.
- the interconnect assembly 420 includes a trace including a plurality of electrically conductive portions, identified with resistors 420 a , 420 b , 420 c , and 420 m with respective resistances, r P11 , r P12 , r P13 and r P1m , and the ellipsis 420 i indicating additional resistors (not shown).
- the plurality of electrically conductive portions are configured both to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 .
- the plurality of electrically conductive portions are configured such that, upon interconnecting the first solar cell 410 and the second solar cell 430 , the plurality of electrically conductive portions are connected electrically in parallel between the first solar cell 410 and the second solar cell 430 .
- the plurality of electrically conductive portions is configured such that equivalent series resistance, R S1 , of the interconnect assembly 420 including the parallel network of resistors 420 a , 420 b , 420 c , 420 i , and 420 m , is less than the resistance of any one resistor in the parallel network. Therefore, by connecting the first solar cell 410 to the second solar cell 430 , with the interconnect assembly 420 , the series resistance, R S1 , of the interconnect assembly 420 can be reduced lowering the effective series resistance between solar cells in the solar-cell module 404 improving the solar-cell-module efficiency.
- the configuration of the plurality of electrically conductive portions due to this parallel arrangement of electrically conductive portions between the first solar cell 410 and the second solar cell 430 provides a redundancy of electrical current carrying capacity between interconnected solar cells should any one of the plurality of electrically conductive portions become damaged, or its reliability become impaired.
- embodiments of the present invention provide that the plurality of electrically conductive portions is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired, because the loss of electrical current through any one electrically conductive portion will be compensated for by the plurality of the unimpaired parallel electrically conductive portions coupling the first solar cell 410 with the second solar cell 430 .
- substantially undiminished with respect to solar-cell efficiency means that the solar-cell efficiency is not reduced below an acceptable level of productive performance.
- the plurality of electrically conductive portions may be configured in pairs of electrically conductive portions, for example, identified with resistors 420 a and 420 b .
- the plurality of electrically conductive portions may be configured such that solar-cell efficiency is substantially undiminished even in an event that, in every pair of electrically conductive portions of the plurality of electrically conductive portions, one electrically conductive portion of the pair is conductively impaired.
- each member of a pair of electrically conductive portions may be electrically equivalent to the other member of the pair, but need not be electrically equivalent to the other member of the pair, it only being necessary that in an event one member, a first member, of the pair becomes conductively impaired the other member, a second member, is configured such that solar-cell efficiency is substantially undiminished.
- a plan view 400 B of the interconnect assembly 420 of FIG. 4A is shown that details the physical interconnection of two solar cells 410 and 430 in the solar-cell module 404 .
- the solar-cell module 404 includes the first solar cell 410 , at least the second solar cell 430 and the interconnect assembly 420 disposed above a light-facing side 416 of the absorber layer of the first solar cell 410 .
- the interconnect assembly 420 includes a trace comprising a plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , previously identified herein with the resistors 420 a , 420 b , 420 c , 420 i and 420 m described in FIG. 400A , where the ellipsis of 420 i indicates additional electrically conductive portions (not shown).
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is configured both to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 .
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is conductively impaired.
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m further includes a first portion 420 a of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m configured both to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 and a second portion 420 b of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m configured both to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 .
- the first portion 420 a includes a first end 420 p distal from the second solar cell 430 .
- the second portion 420 b includes a second end 420 q distal from the second solar cell 430 .
- the second portion 420 b is disposed proximately to the first portion 420 a and electrically connected to the first portion 420 a such that the first distal end 420 p is electrically connected to the second distal end 420 q , for example, at first junction 420 r , or by a linking portion, such that the second portion 420 b is configured electrically in parallel to the first portion 420 a when configured to interconnect to the second solar cell 430 .
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m may further include the second portion 420 b including a third end 420 s distal from the first solar cell 410 and a third portion 420 c of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m configured both to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 .
- the third portion 420 c includes a fourth end 420 t distal from the first solar cell 410 .
- the third portion 420 c is disposed proximately to the second portion 420 b and electrically connected to the second portion 420 b such that the third distal end 420 s is electrically connected to the fourth distal end 420 t , for example, at second junction 420 u , or by a linking portion, such that the third portion 420 c is configured electrically in parallel to the second portion 420 b when configured to interconnect with the first solar cell 430 .
- the nature of the parallel connection between electrically conductive portions interconnecting a first solar cell and a second solar cell is such that, for distal ends of electrically conductive portions not directly joined together, without limitation thereto, the metallic substrate of a second solar cell and a TCO layer of the first solar cell may provide the necessary electrical coupling.
- distal ends 420 v and 420 s are electrically coupled through a low resistance connection through a metallic substrate 430 c of second solar cell 430 .
- distal ends 420 w and 420 q are electrically coupled through the low resistance connection through the TCO layer 410 b of first solar cell 410 .
- FIG. 4B illustrates the manner in which the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is conductively impaired, for example, second portion 420 b .
- An arrow 448 indicates the nominal electron-flow through a third portion 420 c of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m essentially unaffected by open-circuit defect 440 .
- an electron-flow indicated by arrow 448 would normally flow through any one electrically conductive portion of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , in particular, second portion 420 b .
- this electron-flow divides into two portions shown by arrows 442 and 444 : arrow 442 corresponding to that portion of the normal electron-flow flowing to the right along the second portion 420 b to the second solar cell 430 , and arrow 444 corresponding to that portion of the normal electron-flow flowing to the left along the second portion 420 b to the first portion 420 a and then to the right along the first portion 420 a to the second solar cell 430 .
- the net electron-flow represented by arrow 446 flowing to the right along the first portion 420 a is consequently larger than what would normally flow to the right along the first portion 420 a to the second solar cell 430 in the absence of the open-circuit defect 440 .
- open-circuit defect 440 is for illustration purposes only and that embodiments of the present invention compensate for other types of defects in an electrically conductive portion, in general, such as, without limitation to: a delamination of an electrically conductive portion from the first solar cell 410 , corrosion of an electrically conductive portion, and even complete loss of an electrically conductive portion.
- the physical spacing between adjacent electrically conductive portions identified with double-headed arrow 449 , may be chosen such that solar-cell efficiency is substantially undiminished.
- embodiments of the present invention embrace, without limitation thereto, other physical spacings between adjacent electrically conductive portions in the event defects are less severe than those causing a complete loss of one of the electrically conductive portions.
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m may be connected electrically in series to form a single continuous electrically conductive line.
- the trace that includes the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m may be disposed in a serpentine pattern such that the interconnect assembly 420 is configured to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 , as shown.
- a cross-sectional, elevation view 400 C of the interconnect assembly 420 is shown that further details the physical interconnection of two solar cells 410 and 430 in the solar-cell module 404 .
- Projections 474 and 478 of planes orthogonal to both of the views in FIGS. 4B and 4C , and coincident with the ends of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m show the correspondence between features of the plan view 400 B of FIG. 4B and features in the cross-sectional, elevation view 400 C of FIG. 4C .
- a combined solar-cell, interconnect assembly 494 includes the first solar cell 410 and the interconnect assembly 420 .
- the interconnect assembly 420 includes the trace disposed above the light-facing side 416 of the first solar cell 410 , the trace further including the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m .
- All electrically conductive portions of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m are configured to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 .
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m may be configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is conductively impaired.
- any of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m may be configured to interconnect electrically to the second solar cell 430 .
- the first solar cell 410 of the combined solar-cell, interconnect assembly 494 may include a metallic substrate 410 c and an absorber layer 410 a .
- the absorber layer 410 a of the first solar cell 410 may include copper indium gallium diselenide (CIGS).
- the absorber layer 410 a may be used as the absorber layer 410 a .
- semiconductors such as silicon and cadmium telluride, as well as other semiconductors, may be used as the absorber layer 410 a.
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m of the combined solar-cell, interconnect assembly 494 further includes the first portion 420 a of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m configured to collect current from the first solar cell 410 and the second portion 420 b of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m configured to collect current from the first solar cell 410 .
- the first portion 420 a includes the first end 420 p distal from an edge 414 of the first solar cell 410 .
- the second portion 420 b includes the second end 420 q distal from the edge 414 of the first solar cell 410 .
- the second portion 420 b is disposed proximately to the first portion 420 a and electrically connected to the first portion 420 a such that the first distal end 420 p is electrically connected to the second distal end 420 q such that the second portion 420 b is configured electrically in parallel to the first portion 420 a when configured to interconnect to the second solar cell 430 .
- the interconnect assembly 420 further includes a top carrier film 450 .
- the top carrier film 450 includes a first substantially transparent, electrically insulating layer coupled to the trace and disposed above a top portion of the trace.
- the first substantially transparent, electrically insulating layer allows for forming a short-circuit-preventing portion 454 at an edge 434 of the second solar cell 430 .
- the first substantially transparent, electrically insulating layer allows for forming the short-circuit-preventing portion 454 at the edge 434 of the second solar cell 430 to prevent the first portion 420 a from short circuiting an absorber layer 430 a of the second solar cell 430 in the event that the first portion 420 a buckles and rides up a side 432 of second solar cell 430 .
- the edge 434 is located at the intersection of the side 432 of the second solar cell 430 and a back side 438 of the second solar cell 430 that couples with the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , for example, first portion 420 a as shown.
- the second solar cell 430 may include the absorber layer 430 a , a TCO layer 430 b , and the metallic substrate 430 c ; a backing layer (not shown) may also be disposed between the absorber layer 430 a and the metallic substrate 430 c .
- an integrated busbar-solar-cell-current collector (not shown in FIG. 4C , but which is shown in FIGS. 6A and 6B ) may be disposed and coupled to the second solar cell 430 to provide interconnection with a load (not shown).
- another interconnect assembly may be disposed and coupled to the second solar cell 430 to provide interconnection with additional solar-cells (not shown) in the solar-cell module 404 .
- the interconnect assembly 420 further includes a bottom carrier film 460 .
- the bottom carrier film 460 may include a second electrically insulating layer coupled to the trace and disposed below a bottom portion of the trace.
- the bottom carrier film 460 may include a carrier film selected from a group consisting of a second electrically insulating layer, a structural plastic layer, and a metallic layer, and is coupled to the trace and is disposed below a bottom portion of the trace.
- the second electrically insulating layer allows for forming an edge-protecting portion 464 at the edge 414 of the first solar cell 410 .
- a supplementary isolation strip (not shown) of a third electrically insulating layer may be disposed between the bottom carrier film 460 and the first portion 420 a of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , or alternatively between the bottom carrier film 460 and the edge 414 , to provide additional protection at the edge 414 .
- the supplementary isolation strip may be as wide as 5 millimeters (mm) in the direction of the double-headed arrow showing the separation 472 , and may extend along the full length of a side 412 of the first solar cell 410 .
- the edge 414 is located at the intersection of the side 412 of the first solar cell 410 and a light-facing side 416 of the first solar cell 410 that couples with the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , for example, first portion 420 a as shown.
- the first solar cell 410 may include the absorber layer 410 a , the TCO layer 410 b , and the metallic substrate 410 c ; a backing layer (not shown) may also be disposed between the absorber layer 410 a and the metallic substrate 410 c .
- a first busbar (not shown) may be disposed and coupled to the first solar cell 410 to provide interconnection with a load (not shown).
- another interconnect assembly (not shown) may be disposed and coupled to the first solar cell 410 to provide interconnection with additional solar-cells (not shown) in the solar-cell module 404 .
- FIGS. 4D and 4E in accordance with embodiments of the present invention, cross-sectional, elevation views 400 D and 400 E, respectively, of two alternative interconnect assemblies that minimize the separation 472 (see FIG. 4B ) between the first solar cell 410 and the second solar cell 430 to improve the solar-cell-module efficiency of the solar-cell module 404 are shown.
- the side 412 of the first solar cell 410 essentially coincides with the side 432 of the second solar cell 430 .
- FIG. 4D shows an edge-conforming interconnect assembly for the physical interconnection of the two solar cells 410 and 430 in the solar-cell module 404 .
- the interconnect assembly 420 further includes the bottom carrier film 460 .
- the bottom carrier film 460 includes a second electrically insulating layer coupled to the trace and disposed below a bottom portion of the trace.
- the bottom carrier film 460 may include a carrier film selected from a group consisting of a second electrically insulating layer, a structural plastic layer, and a metallic layer, and is coupled to the trace and is disposed below a bottom portion of the trace.
- the second electrically insulating layer allows for forming the edge-protecting portion 464 at the edge 414 of the first solar cell 410 .
- the bottom carrier film 460 and the first portion 420 a of the interconnect assembly 420 may be relatively flexible and compliant allowing them to wrap around the edge 414 and down the side 412 of the first solar cell 410 , as shown.
- the edge 414 is located at the intersection of the side 412 of the first solar cell 410 and the light-facing side 416 of the first solar cell 410 that couples with the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , for example, first portion 420 a as shown.
- the first solar cell 410 may include the absorber layer 410 a , a TCO layer 410 b , and the metallic substrate 410 c ; a backing layer (not shown) may also be disposed between the absorber layer 410 a and the metallic substrate 410 c .
- first solar cell 410 Below the back side 418 of the first solar cell 410 , another interconnect assembly (not shown) or first busbar (not shown) may be disposed and coupled to the first solar cell 410 as described above for FIG. 4C . If an additional solar cell (not shown) is interconnected to the back side 418 of the first solar cell 410 as in the shingled-solar-cell arrangement of FIG. 4E , the first solar cell 410 would be pitched upward at its left-hand side and interconnected to another interconnect assembly similar to the manner in which the second solar cell 430 is shown interconnected with solar cell 410 at side 412 in FIG. 4E .
- the interconnect assembly 420 further includes the top carrier film 450 .
- the top carrier film 450 includes a first substantially transparent, electrically insulating layer coupled to the trace and disposed above a top portion of the trace.
- the first substantially transparent, electrically insulating layer allows for forming the short-circuit-preventing portion 454 at the edge 434 of the second solar cell 430 to prevent the first portion 420 a from short circuiting the absorber layer 430 a of the second solar cell 430 in the event that the first portion 420 a rides up the side 432 of second solar cell 430 .
- the edge 434 is located at the intersection of the side 432 of the second solar cell 430 and the back side 438 of the second solar cell 430 that couples with the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , for example, first portion 420 a as shown.
- the top carrier film 450 may be relatively flexible and compliant allowing it to follow the conformation of the bottom carrier film 460 and the first portion 420 a of the interconnect assembly 420 underlying it that wrap around the edge 414 and down the side 412 of the first solar cell 410 , as shown.
- the second solar cell 430 may include the absorber layer 430 a , the TCO layer 430 b , and the metallic substrate 430 c ; a backing layer (not shown) may also be disposed between the absorber layer 430 a and the metallic substrate 430 c . Also, in the case of the edge-conforming interconnect assembly, the absorber layer 430 a , TCO layer 430 b , and metallic substrate 430 c of the second solar cell 430 may be relatively flexible and compliant allowing them to follow the conformation of the underlying interconnect assembly 420 that wraps around the edge 414 and down the side 412 of the first solar cell 410 .
- an integrated busbar-solar-cell-current collector (not shown in FIG. 4C , but which is shown in FIGS. 6A and 6B ), or alternatively another interconnect assembly (not shown), may be disposed on and coupled to the second solar cell 430 , as described above for FIG. 4C .
- FIG. 4F a plan view 400 F of an alternative interconnect assembly for the interconnect assembly 420 of FIG. 4A is shown that details the physical interconnection of two solar cells 410 and 430 in the solar-cell module 404 .
- the solar-cell module 404 includes the first solar cell 410 , at least the second solar cell 430 and the interconnect assembly 420 disposed above the light-facing side 416 of the absorber layer of the first solar cell 410 .
- the edges 414 and 434 of the solar cells 410 and 430 may be separated by the separation 472 as shown in FIG. 4F ; or alternatively, the edges 414 and 434 of the solar cells 410 and 430 may essentially coincide as discussed above for FIGS.
- the interconnect assembly 420 includes a trace comprising a plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , previously identified herein with the resistors 420 a , 420 b , 420 c , 420 i and 420 m described in FIG. 400A , where the ellipsis of 420 i indicates additional electrically conductive portions (not shown).
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is configured both to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 .
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is conductively impaired.
- the detailed configuration of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is shown without electrically connecting trace portions, for example, junctions formed in the trace or linking portions of the trace.
- electrically connecting trace portions of the trace have been cut away, removed, or are otherwise absent, from the distal ends of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , as shown in FIG. 4F .
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m may be linked together instead indirectly by the TCO layer 410 b of the first solar cell 410 at distal ends of the trace disposed over the first solar cell 410 , for example, first distal end 420 p of first portion 420 a and second distal end 420 q of second portion 420 b by portions of the TCO layer 410 b of the first solar cell 410 that lie in between the distal ends 420 p and 420 q .
- the distal ends 420 w and 420 q are electrically coupled through the low resistance connection through the TCO layer 410 b of first solar cell 410 .
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m may be linked together instead indirectly by the metallic substrate 430 c , or intervening backing layer (not shown), of the first solar cell 430 at distal ends of the trace disposed under the second solar cell 430 , for example, third distal end 420 s of second portion 420 b and fourth distal end 420 t of third portion 420 c by portions of the metallic substrate 430 c of the second solar cell 430 that lie in between the distal ends 420 s and 420 t .
- the distal ends 420 v and 420 s are electrically coupled through a low resistance connection through the metallic substrate 430 c of second solar cell 430 .
- FIG. 4F illustrates the open-circuit defect 440 such that second portion 420 b is conductively impaired.
- FIG. 4F illustrates the manner in which the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is conductively impaired, for example, second portion 420 b .
- An arrow 480 indicates the nominal electron-flow through an m-th portion 420 m of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m essentially unaffected by open-circuit defect 440 .
- an electron-flow indicated by arrow 480 would normally flow through any one electrically conductive portion of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , in particular, second portion 420 b .
- the net electron-flow represented by arrow 486 flowing to the right along the first portion 420 a is consequently larger than what would normally flow to the right along the first portion 420 a to the second solar cell 430 in the absence of the open-circuit defect 440 ; and, the net electron-flow represented by arrow 488 flowing to the right along the third portion 420 c is consequently larger than what would normally flow to the right along the third portion 420 c to the second solar cell 430 in the absence of the open-circuit defect 440 .
- open-circuit defect 440 is for illustration purposes only and that embodiments of the present invention compensate for other types of defects in an electrically conductive portion, in general, such as, without limitation to: a delamination of an electrically conductive portion from the first solar cell 410 , corrosion of an electrically conductive portion, and even complete loss of an electrically conductive portion.
- the physical spacing between adjacent electrically conductive portions may be chosen such that solar-cell efficiency is substantially undiminished.
- embodiments of the present invention embrace, without limitation thereto, other physical spacings between adjacent electrically conductive portions in the event defects are less severe than those causing a complete loss of one of the electrically conductive portions.
- a plan view 400 G of the interconnect assembly 420 of FIG. 4A is shown that details the physical interconnection of two solar cells 410 and 430 in the solar-cell module 404 .
- the solar-cell module 404 includes the first solar cell 410 , at least the second solar cell 430 and the interconnect assembly 420 disposed above a light-facing side 416 of the absorber layer of the first solar cell 410 .
- the interconnect assembly 420 includes a trace comprising a plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , previously identified herein with the resistors 420 a , 420 b , 420 c , 420 i and 420 m described in FIG. 400A , where the ellipsis of 420 i indicates additional electrically conductive portions (not shown).
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is configured both to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 .
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is conductively impaired.
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m further includes a first portion 420 a of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m configured both to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 and a second portion 420 b of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m configured both to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 .
- the first portion 420 a includes a first end 420 p distal from the second solar cell 430 .
- the second portion 420 b includes a second end 420 q distal from the second solar cell 430 .
- the second portion 420 b is disposed proximately to the first portion 420 a and electrically connected to the first portion 420 a such that the first distal end 420 p is electrically connected to the second distal end 420 q , for example, at first junction 420 r , or by a linking portion, such that the second portion 420 b is configured electrically in parallel to the first portion 420 a when configured to interconnect to the second solar cell 430 .
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m may further include the second portion 420 b including a third end 420 s distal from the first solar cell 410 and a third portion 420 c of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m configured both to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 .
- the third portion 420 c includes a fourth end 420 t distal from the first solar cell 410 .
- the third portion 420 c is disposed proximately to the second portion 420 b and electrically connected to the second portion 420 b such that the third distal end 420 s is electrically connected to the fourth distal end 420 t , for example, at second junction 420 u , or by a linking portion, such that the third portion 420 c is configured electrically in parallel to the second portion 420 b when configured to interconnect with the first solar cell 430 .
- the nature of the parallel connection between electrically conductive portions interconnecting a first solar cell and a second solar cell is such that, for distal ends of electrically conductive portions not directly joined together, without limitation thereto, the metallic substrate of a second solar cell and a TCO layer of the first solar cell may provide the necessary electrical coupling.
- distal ends 420 v and 420 s are electrically coupled through a low resistance connection through a metallic substrate 430 c of second solar cell 430 .
- distal ends 420 w and 420 q are electrically coupled through the low resistance connection through the TCO layer 410 b of first solar cell 410 .
- FIG. 4G illustrates the manner in which the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is conductively impaired, for example, second portion 420 b .
- An arrow 448 indicates the nominal electron-flow through a third portion 420 c of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m essentially unaffected by open-circuit defect 440 .
- an electron-flow indicated by arrow 448 would normally flow through any one electrically conductive portion of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , in particular, second portion 420 b .
- this electron-flow divides into two portions shown by arrows 442 and 444 : arrow 442 corresponding to that portion of the normal electron-flow flowing to the right along the second portion 420 b to the second solar cell 430 , and arrow 444 corresponding to that portion of the normal electron-flow flowing to the left along the second portion 420 b to the first portion 420 a and then to the right along the first portion 420 a to the second solar cell 430 .
- the net electron-flow represented by arrow 446 flowing to the right along the first portion 420 a is consequently larger than what would normally flow to the right along the first portion 420 a to the second solar cell 430 in the absence of the open-circuit defect 440 .
- open-circuit defect 440 is for illustration purposes only and that embodiments of the present invention compensate for other types of defects in an electrically conductive portion, in general, such as, without limitation to: a delamination of an electrically conductive portion from the first solar cell 410 , corrosion of an electrically conductive portion, and even complete loss of an electrically conductive portion.
- the physical spacing between adjacent electrically conductive portions identified with double-headed arrow 449 , may be chosen such that solar-cell efficiency is substantially undiminished.
- embodiments of the present invention embrace, without limitation thereto, other physical spacings between adjacent electrically conductive portions in the event defects are less severe than those causing a complete loss of one of the electrically conductive portions.
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m may be connected electrically in series to form a single continuous electrically conductive line.
- the trace that includes the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m may be disposed in a serpentine pattern such that the interconnect assembly 420 is configured to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 , as shown.
- a cross-sectional, elevation view 400 H of the interconnect assembly 420 is shown that further details the physical interconnection of two solar cells 410 and 430 in the solar-cell module 404 .
- Projections 474 and 478 of planes orthogonal to both of the views in FIGS. 4G and 4H , and coincident with the ends of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m show the correspondence between features of the plan view 400 G of FIG. 4G and features in the cross-sectional, elevation view 400 H of FIG. 4H .
- the solar-cell module 404 is shown with separation 472 between the first solar cell 410 and the second solar cell 430 , there need not be such separation 472 between the first solar cell 410 and the second solar cell 430 . In some embodiments, the separation will be less than that depicted in the figures. In some embodiments, the cells may overlap.
- a combined solar-cell, interconnect assembly 494 includes the first solar cell 410 and the interconnect assembly 420 .
- the interconnect assembly 420 includes the trace disposed above the light-facing side 416 of the first solar cell 410 , the trace further including the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m . All electrically conductive portions of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m are configured to collect current from the first solar cell 410 and to interconnect electrically to the second solar cell 430 .
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m may be configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m is conductively impaired. Also, any of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m may be configured to interconnect electrically to the second solar cell 430 .
- the first solar cell 410 of the combined solar-cell, interconnect assembly 494 may include a metallic substrate 410 c and an absorber layer 410 a .
- the absorber layer 410 a of the first solar cell 410 may include copper indium gallium diselenide (CIGS).
- CIGS copper indium gallium diselenide
- other semiconductors having the chalcopyrite crystal structure for example, chemically homologous compounds with the compound CIGS having the chalcopyrite crystal structure, in which alternative elemental constituents are substituted for Cu, In, Ga, and/or Se, may be used as the absorber layer 410 a .
- semiconductors such as silicon and cadmium telluride, as well as other semiconductors, may be used as the absorber layer 410 a.
- the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m of the combined solar-cell, interconnect assembly 494 further includes the first portion 420 a of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m configured to collect current from the first solar cell 410 and the second portion 420 b of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m configured to collect current from the first solar cell 410 .
- the first portion 420 a includes the first end 420 p distal from an edge 414 of the first solar cell 410 .
- the second portion 420 b includes the second end 420 q distal from the edge 414 of the first solar cell 410 .
- the second portion 420 b is disposed proximately to the first portion 420 a and electrically connected to the first portion 420 a such that the first distal end 420 p is electrically connected to the second distal end 420 q such that the second portion 420 b is configured electrically in parallel to the first portion 420 a when configured to interconnect to the second solar cell 430 .
- the interconnect assembly 420 further includes top and bottom carrier films 450 and 460 , respectively.
- the top carrier film 450 includes a first substantially transparent, electrically insulating layer coupled to the trace 420 and disposed above a top portion 420 x of the trace 420 .
- the first substantially transparent, electrically insulating layer terminates a small distance short of the edge 412 of the first cell 410 .
- the bottom carrier film 460 may include a second electrically insulating layer coupled to the trace 420 and disposed below a bottom portion of the trace 420 a .
- the bottom carrier film 460 may include a carrier film selected from a group consisting of a second electrically insulating layer, a structural plastic layer, and a metallic layer, and is coupled to the trace and is disposed below a bottom portion of the trace.
- the second electrically insulating layer allows for forming an edge-protecting portion 464 at the edge 414 of the first solar cell 410 .
- a supplementary isolation strip (not shown) of a third electrically insulating layer may be disposed between the bottom carrier film 460 and the first portion 420 a of the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , or alternatively between the bottom carrier film 460 and the edge 414 , to provide additional protection at the edge 414 .
- the supplementary isolation strip may be as wide as 5 millimeters (mm) in the direction of the double-headed arrow showing the separation 472 , and may extend along the full length of a side 412 of the first solar cell 410 .
- the edge 414 is located at the intersection of the side 412 of the first solar cell 410 and a light-facing side 416 of the first solar cell 410 that couples with the plurality of electrically conductive portions 420 a , 420 b , 420 c , 420 i and 420 m , for example, first portion 420 a as shown.
- the first solar cell 410 may include the absorber layer 410 a , the TCO layer 410 b , and the metallic substrate 410 c ; a backing layer (not shown) may also be disposed between the absorber layer 410 a and the metallic substrate 410 c .
- a first busbar (not shown) may be disposed and coupled to the first solar cell 410 to provide interconnection with a load (not shown).
- another interconnect assembly (not shown) may be disposed and coupled to the first solar cell 410 to provide interconnection with additional solar-cells (not shown) in the solar-cell module 404 .
- the second solar cell 430 may include the absorber layer 430 a , a TCO layer 430 b , and the metallic substrate 430 c ; a backing layer (not shown) may also be disposed between the absorber layer 430 a and the metallic substrate 430 c .
- an integrated busbar-solar-cell-current collector (not shown in FIG. 4H , but which is shown in FIGS. 6A and 6B ) may be disposed and coupled to the second solar cell 430 to provide interconnection with a load (not shown).
- another interconnect assembly may be disposed and coupled to the second solar cell 430 to provide interconnection with additional solar-cells (not shown) in the solar-cell module 404 .
- FIG. 5A a plan view 500 A of the combined applicable carrier film, interconnect assembly 504 is shown.
- FIG. 5A shows the physical arrangement of a trace 520 with respect to a top carrier film 550 and a bottom carrier film 560 in the combined applicable carrier film, interconnect assembly 504 .
- the combined applicable carrier film, interconnect assembly 504 includes the top carrier film 550 and the trace 520 including a plurality of electrically conductive portions 520 a , 520 b , 520 c , 520 d , 520 e , 520 f , 520 g , 520 m and 520 i , the latter corresponding to the ellipsis indicating additional electrically conductive portions (not shown).
- the plurality of electrically conductive portions 520 a through 520 m is configured both to collect current from a first solar cell 510 (shown in FIG. 5D ) and to interconnect electrically to a second solar cell (not shown). As shown in FIG.
- the plurality of electrically conductive portions 520 a through 520 m run over the top of the first solar cell 510 on the left and over an edge 514 of the first solar cell 510 to the right under an edge 534 of, and underneath, the second solar cell (not shown).
- the top carrier film 550 includes a first substantially transparent, electrically insulating layer 550 A (shown in FIG. 5B ).
- the plurality of electrically conductive portions 520 a through 520 m is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions 520 a through 520 m is conductively impaired.
- substantially transparent with respect to a substantially transparent, electrically insulating layer means that light passes through the substantially transparent, electrically insulating layer with negligible absorption.
- the first substantially transparent, electrically insulating layer 550 a is coupled to the trace 520 and disposed above a top portion of the trace 520 (shown in FIG. 5B ) as indicated by the dashed portions of the trace 520 on the left of FIG. 5A .
- FIG. 5B a plan view 500 B of the combined applicable carrier film, interconnect assembly 504 is shown.
- FIG. 5B shows the physical arrangement of a trace 520 with respect to a top carrier film 550 and a bottom carrier film 560 in the combined applicable carrier film, interconnect assembly 504 .
- the combined applicable carrier film, interconnect assembly 504 includes the top carrier film 550 and the trace 520 including a plurality of electrically conductive portions 520 a , 520 b , 520 c , 520 d , 520 e , 520 f , 520 g , 520 m and 520 i , the latter corresponding to the ellipsis indicating additional electrically conductive portions (not shown).
- the plurality of electrically conductive portions 520 a through 520 m is configured both to collect current from a first solar cell 510 (shown in FIG. 5E ) and to interconnect electrically to a second solar cell (not shown). As shown in FIG.
- the plurality of electrically conductive portions 520 a through 520 m run over the top of the first solar cell 510 on the left and over an edge 514 of the first solar cell 510 to the right under an edge 534 of, and underneath, the second solar cell (not shown).
- the top carrier film 550 includes a first substantially transparent, electrically insulating layer 550 a (shown in FIG. 5D ).
- the plurality of electrically conductive portions 520 a through 520 m is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions 520 a through 520 m is conductively impaired.
- substantially transparent with respect to a substantially transparent, electrically insulating layer means that light passes through the substantially transparent, electrically insulating layer with negligible absorption.
- the first substantially transparent, electrically insulating layer 550 a is coupled to the trace 520 and disposed above a top portion of the trace 520 (shown in FIG. 5D ) as indicated by the dashed portions of the trace 520 on the left of FIG. 5B .
- FIG. 5C provides a further illustration, in cross-section, of a specific embodiment of the present invention in accordance with that described with reference to FIG. 5B .
- the figure shows aspects of the interconnection arrangement of two solar cells.
- the first solar cell 570 can be constructed as previously described herein and include a CIGS thin film 572 on a stainless steel substrate 574 .
- the second solar cell 580 can have the same construction as the first cell 570 , again including a CIGS thin film 582 on a stainless steel substrate 584 .
- the two cells 570 and 580 are arranged so that there is a small gap 599 , generally as small a gap as possible, for example about 1-2 mm, between their respective closest edges 575 and 585 . As noted above, in alternative embodiments, the gap may be wider or the cells may even slightly overlap.
- the cells are interconnected by an interconnect 590 that includes top and bottom carrier films (polymer decals) 592 and 594 and a conductive wire 596 .
- the wire can be about 34 gauge and the decals can be composed of a layer of about 2 mil thick PET between layers of about 2 mil thick Surlyn adhesive.
- the decals 592 , 594 and wire 596 are arranged so that a portion of the wire 596 is exposed for electrical contact with a top side 573 of the first cell 570 and the bottom side 583 of the second solar cell 580 .
- the top decal 592 covers the top of the wire 596 and extends from a first end 597 of the wire 596 over the first solar cell 570 almost to the edge 575 of the first solar cell 570 .
- the bottom decal 594 covers the bottom of the wire 596 , slightly overlaps the first decal 592 in extent, and extends to a second end 598 of the wire 596 under the second solar cell 580 .
- FIGS. 5D and 5E a cross-sectional, elevation view of the combined applicable carrier film, interconnect assembly 504 of FIG. 5A or 5B is shown.
- the cross-section of the view is taken along a cut parallel to the edge 514 of the first solar cell 510 .
- the cross-sectional, elevation view of FIG. 5D shows the physical arrangement of the trace 520 with respect to the top carrier film 550 in the combined applicable carrier film, interconnect assembly 504 prior to disposition on the first solar cell 510 .
- the top carrier film 550 and the trace 520 are configured for applying to a light-facing side of the first solar cell 510 both to collect current from the first solar cell 510 and to interconnect electrically to the second solar cell (not shown).
- the first solar cell 510 may include an absorber layer 510 a , a TCO layer 510 b , and a metallic substrate 510 c ; the backing layer (not shown) may also be disposed between the absorber layer 510 a and the metallic substrate 510 c .
- the first substantially transparent, electrically insulating layer 550 a holds the trace 520 down in contact with the first solar cell 510 and allows for forming a short-circuit-preventing portion at an edge of the second solar cell (not shown).
- the top carrier film 550 further includes a first substantially transparent, adhesive medium 550 b coupling the trace 520 to the substantially transparent, electrically insulating layer 550 a .
- the top carrier film 550 prior to disposition on the first solar cell 510 , the top carrier film 550 lies relatively flat across the top portion of the trace 520 , for example, as for the conformational state of the top carrier film 550 immediately after roll-to-roll fabrication of the combined applicable carrier film, interconnect assembly 504 .
- the first substantially transparent, adhesive medium 550 b allows for coupling the trace 520 to the first solar cell 510 without requiring solder.
- the first substantially transparent, electrically insulating layer 550 a may include a structural plastic material, such as polyethylene terephthalate (PET).
- a first substantially transparent, adhesive medium such as first substantially transparent, adhesive medium 550 b may be included, without limitation thereto, in a top carrier film of: the combined applicable carrier film, interconnect assembly 504 , the interconnect assembly 320 , the integrated busbar-solar-cell-current collector 690 (see FIG. 6B ), the combined solar-cell, interconnect assembly 494 , or the interconnect assembly 420 of the solar-cell module 404 .
- the combined applicable carrier film, interconnect assembly 504 further includes the bottom carrier film 560 .
- the bottom carrier film 560 includes a second electrically insulating layer, like 550 a , coupled to the trace 520 and disposed below a bottom portion of the trace 520 , as indicated by the solid-line portions of the trace 520 on the right of FIG. 5A .
- the bottom carrier film 560 may include a carrier film selected from a group consisting of a second electrically insulating layer, a structural plastic layer, and a metallic layer, and is coupled to the trace 520 and is disposed below a bottom portion of the trace 520 .
- the second electrically insulating layer like 550 a , holds the trace 520 down in contact with a back side of the second solar cell (not shown) and allows for forming an edge-protecting portion at the edge 514 of the first solar cell 510 .
- the bottom carrier film 560 further includes a second adhesive medium, like 550 b , coupling the trace to the second electrically insulating layer, like 550 a .
- the second adhesive medium, like 550 b allows for coupling the trace 520 to the back side of the second solar cell (not shown) without requiring solder.
- the second electrically insulating layer, like 550 a includes a structural plastic material, such as PET.
- a second adhesive medium may be included, without limitation thereto, in a bottom carrier film of: the combined applicable carrier film, interconnect assembly 504 , the interconnect assembly 320 , the combined solar-cell, interconnect assembly 494 , or the interconnect assembly 420 of the solar-cell module 404 .
- the trace 520 may be disposed in a serpentine pattern that allows for collecting current from the first solar cell 510 (shown in FIG. 5D ) and electrically interconnecting to the second solar cell (not shown). It should be noted that neither the first solar cell 510 nor the second solar cell (not shown) are shown in FIG. 5A or 5B so as not to obscure the structure of the combined applicable carrier film, interconnect assembly 504 . As shown in FIG.
- the combined applicable carrier film, interconnect assembly 504 includes the trace 520 including the plurality of electrically conductive portions 520 a through 520 m that may run in a serpentine pattern back and forth between the first solar cell 510 and the second solar cell (not shown).
- the serpentine pattern is such that adjacent electrically conductive portions of the plurality of electrically conductive portions 520 a through 520 m are configured in pairs of adjacent electrically conductive portions: 520 a and 520 b , 520 c and 520 d , 520 e and 520 f , etc.
- the pairs of adjacent electrically conductive portions may be configured in a regular repeating pattern of equally spaced adjacent electrically conductive portions.
- the trace 520 including the plurality of electrically conductive portions 520 a through 520 m is disposed between the top carrier film 550 disposed above a top portion of the trace 520 and the bottom carrier film 560 disposed below a bottom portion of the trace 520 .
- the first substantially transparent, electrically insulating layer 550 a of top carrier film 550 and the second electrically insulating layer, or alternatively, structural plastic layer or metallic layer, of bottom carrier film 560 are coupled to the trace 520 with a first substantially transparent, adhesive medium 550 b and second adhesive medium which also serve to couple the trace 520 to the first solar cell 510 , which may be located on the left, and the second solar cell, which may be located on the right.
- the trace is sandwiched between the two carrier films 550 and 560 ; the overlapping region of the two carrier films 550 and 560 extends somewhat beyond the respective edges 514 and 534 of the first and second solar cells so as to form, respectively, an edge-protecting portion at the edge 514 of the first solar cell, and a short-circuit-preventing portion at the edge 534 of the second solar cell, from the trace 520 that crosses the edges 514 and 534 .
- the trace is carried by bottom carrier film 560 ; the top carrier film terminates just short of the edge 514 of the first solar cell 510 .
- the bottom carrier film 560 prevents contact between the trace 520 and the edge 514 of the first solar cell.
- the trace 520 may further include an electrically conductive line including a conductive core 520 A with at least one overlying layer 520 B.
- the electrically conductive line may include the conductive core 520 A including a material having greater conductivity than nickel, for example, copper, with an overlying nickel layer 520 B.
- electrically conductive line may include the conductive core 520 A including nickel without the overlying layer 520 B.
- the electrically conductive line may also be selected from a group consisting of a copper conductive core clad with a silver cladding, a copper conductive core clad with a nickel coating further clad with a silver cladding and an aluminum conductive core clad with a silver cladding.
- the trace 520 for collecting current from a solar cell may include an electrically conductive line including the conductive core 520 A, and the overlying layer 520 B that limits current flow to a proximate shunt defect (not shown) in the solar cell.
- the proximate shunt defect may be proximately located in the vicinity of an electrical contact between the overlying layer 520 B of the electrically conductive line and the TCO layer 510 b of the solar cell, for example, first solar cell 510 .
- the overlying layer 520 B of the electrically conductive line of the trace 520 may further include an overlying layer 520 B composed of nickel.
- the conductive core 520 A of the electrically conductive line of the trace 520 may further include nickel.
- the conductive core 520 A may also include a material selected from a group consisting of copper, silver, aluminum, and elemental constituents and alloys having high electrical conductivity, which may be greater than the electrical conductivity of nickel.
- the TCO layer 510 b of the solar cell for example first solar cell 510 , may include a conductive oxide selected from a group consisting of zinc oxide, aluminum zinc oxide and indium tin oxide.
- the absorber layer 510 a for example, absorber layer 112 of FIG.
- first solar cell 510 may include copper indium gallium diselenide (CIGS).
- CGS copper indium gallium diselenide
- semiconductors such as silicon, cadmium telluride, and chalcopyrite semiconductors, as well as other semiconductors, may be used as the absorber layer 510 a .
- an n-type layer, for example, n-type portion 112 b of absorber layer 112 of FIG. 1A , of the solar cell, for example, first solar cell 510 may be disposed on and electrically coupled to a p-type absorber layer, for example, absorber layer 112 of FIG.
- the solar cell for example, first solar cell 510
- the n-type layer for example, n-type portion 112 b of absorber layer 112 of FIG. 1A
- the n-type layer for example, n-type portion 112 b of absorber layer 112 of FIG. 1A
- the n-type layer for example, n-type portion 112 b of absorber layer 112 of FIG. 1A
- a flattened bottom portion of trace 520 increases the contact area with the light-facing side of the first solar cell 510 ; on the other hand, a flattened top portion of trace 520 increases the contact area with a back side of an adjacent solar cell to which the plurality of electrically conductive portions 520 a through 520 m of the trace 520 interconnects.
- a trace such as trace 520 , may be included, without limitation thereto, in: the combined applicable carrier film, interconnect assembly 504 , the interconnect assembly 320 , the integrated busbar-solar-cell-current collector 690 (see FIG. 6B ), the combined solar-cell, interconnect assembly 494 , or the interconnect assembly 420 of the solar-cell module 404 .
- FIG. 6A a plan view 600 A of an integrated busbar-solar-cell-current collector 690 is shown.
- FIG. 6A shows the physical interconnection of a terminating solar cell 660 with a terminating busbar 680 of the integrated busbar-solar-cell-current collector 690 .
- the integrated busbar-solar-cell-current collector 690 includes the terminating busbar 680 and an integrated solar-cell, current collector 670 .
- the integrated solar-cell, current collector 670 includes a plurality of integrated pairs 670 a & b , 670 c & d , 670 e & f , 670 g & h , and 670 l & m and 670 i , the ellipsis indicating additional integrated pairs (not shown), of electrically conductive, electrically parallel trace portions 670 a - m .
- 670 a and 670 b , 670 c and 670 d , 670 e and 670 f , 670 g and 670 h , and 670 l and 670 m are referred to respectively as: 670 a & b , 670 c & d , 670 e & f , 670 g & h , and 670 l & m ; and the electrically conductive, electrically parallel trace portions: 670 a , 670 b , 670 c , 670 d , 670 e , 670 f , 670 g , 670 h , 670 l and 670 m , are referred to as 670 a - m .
- the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h , 670 i and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m is configured both to collect current from the terminating solar cell 660 and to interconnect electrically to the terminating busbar 680 .
- the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h , 670 i and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m is configured such that solar-cell efficiency is substantially undiminished in an event that any one electrically conductive, electrically parallel trace portion, for example, 670 h , of the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h , 670 i and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m is conductively impaired.
- the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h , 670 i and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m further includes a first electrically conductive, electrically parallel trace portion 670 a of a first integrated pair 670 a & b of the electrically conductive, electrically parallel trace portions 670 a - m configured both to collect current from the terminating solar cell 660 and to interconnect electrically to the terminating busbar 680 , and a second electrically conductive, electrically parallel trace portion 670 b of the first integrated pair 670 a & b of the electrically conductive, electrically parallel trace portions 670 a - m configured both to collect current from the terminating solar cell 660 and to interconnect electrically
- the first electrically conductive, electrically parallel trace portion 670 a includes a first end 670 p distal from the terminating busbar 680 located parallel to a side 662 of the terminating solar cell 660 .
- the second electrically conductive, electrically parallel trace portion 670 b includes a second end 670 q distal from the terminating busbar 680 .
- the second electrically conductive, electrically parallel trace portion 670 b is disposed proximately to the first electrically conductive, electrically parallel trace portion 670 a and electrically connected to the first electrically conductive, electrically parallel trace portion 670 a such that the first distal end 670 p is electrically connected to the second distal end 670 q , for example, at first junction 670 r , or by a linking portion, such that the second electrically conductive, electrically parallel trace portion 670 b is configured electrically in parallel to the first electrically conductive, electrically parallel trace portion 670 a when configured to interconnect to the terminating busbar 680 .
- the terminating busbar 680 may be disposed above and connected electrically to extended portions, for example, 670 x and 670 y , of the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h , 670 i and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m configured such that the terminating busbar 680 is configured to reduce shadowing of the terminating solar cell 660 .
- the arrow 648 indicates the nominal electron-flow through a sixth electrically conductive, electrically parallel trace portion 670 f of the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m essentially unaffected by open-circuit defect 640 .
- an electron-flow indicated by arrow 648 would normally flow through any one electrically conductive, electrically parallel trace portion of the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m , in particular, eighth electrically conductive, electrically parallel trace portion 670 h .
- this electron-flow divides into two portions shown by arrows 642 and 644 : arrow 642 corresponding to that portion of the normal electron-flow flowing to the right along the eighth electrically conductive, electrically parallel trace portion 670 h to the terminating busbar 680 , and arrow 644 corresponding to that portion of the normal electron-flow flowing to the left along the eighth electrically conductive, electrically parallel trace portion 670 h to the seventh electrically conductive, electrically parallel trace portion 670 g and then to the right along the seventh electrically conductive, electrically parallel trace portion 670 g to the terminating busbar 680 .
- the net electron-flow represented by arrow 646 flowing to the right along the seventh electrically conductive, electrically parallel trace portion 670 g is consequently larger than what would normally flow to the right along the seventh electrically conductive, electrically parallel trace portion 670 g to the terminating busbar 680 in the absence of the open-circuit defect 640 .
- open-circuit defect 640 is for illustration purposes only and that embodiments of the present invention compensate for other types of defects in an electrically conductive, electrically parallel trace portion, in general, such as, without limitation to: a delamination of an electrically conductive, electrically parallel trace portion from the terminating solar cell 660 , corrosion of an electrically conductive, electrically parallel trace portion, and even complete loss of an electrically conductive, electrically parallel trace portion.
- the physical spacing between adjacent electrically conductive, electrically parallel trace portions identified with double-headed arrow 649 , may be chosen such that solar-cell efficiency is substantially undiminished.
- embodiments of the present invention embrace, without limitation thereto, other physical spacings between adjacent electrically conductive, electrically parallel trace portions in the event defects are less severe than those causing a complete loss of one of the electrically conductive, electrically parallel trace portions.
- FIG. 6B shows the physical interconnection of the terminating solar cell 660 with the terminating busbar 680 in the integrated busbar-solar-cell-current collector 690 .
- the interconnection approach employing a carrier film is also conducive to coupling the integrated busbar-solar-cell-current collector 690 directly to the terminating busbar 680 without requiring solder.
- the integrated busbar-solar-cell-current collector 690 further includes a top carrier film 650 .
- the top carrier film 650 includes a first substantially transparent, electrically insulating layer (not shown, but like 550 a of FIG. 5B ) coupled to the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h , 670 i and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m , for example, electrically conductive, electrically parallel trace portion 670 a , and disposed above a top portion of the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h , 670 i and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m.
- the top carrier film 650 further includes a first adhesive medium (not shown, but like 550 b of FIGS. 5B and 5E ) coupling the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h , 670 i and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m to the electrically insulating layer (like 550 a of FIG. 5B ).
- the first adhesive medium like 550 b of FIGS.
- the terminating solar cell 660 may include an absorber layer 660 a , a TCO layer 660 b , and a metallic substrate 660 c ; a backing layer (not shown) may also be disposed between the absorber layer 660 a and the metallic substrate 660 c .
- the plurality of integrated pairs of electrically conductive, electrically parallel trace portions 670 a - m may be connected electrically in series to form a single continuous electrically conductive line (not shown).
- the single continuous electrically conductive line may be disposed in a serpentine pattern (not shown, but like the pattern of trace 520 in FIG. 5A ) such that the integrated busbar-solar-cell-current collector 690 is configured to collect current from the terminating solar cell 660 and to interconnect electrically to the terminating busbar 680 .
- the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h , 670 i and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m may further include a plurality of electrically conductive lines (not shown, but like trace 520 of FIGS.
- any electrically conductive line of the plurality of electrically conductive lines selected from a group consisting of a copper conductive core clad with a silver cladding, a copper conductive core clad with a nickel coating further clad with a silver cladding and an aluminum conductive core clad with a silver cladding.
- integrated busbar-solar-cell-current collector 690 may include a supplementary isolation strip (not shown) at an edge 664 of the terminating solar cell 660 and running along the length of the side 662 to provide additional protection at the edge 664 and side 662 of the terminating solar cell 660 from the extended portions, for example, 670 x and 670 y , of the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h , 670 i and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m .
- a supplementary isolation strip not shown
- the extended portions may be configured (not shown) to provide stress relief and to allow folding the terminating busbar 680 along edge 664 under a back side 668 and at the side 662 of terminating solar cell 660 , so that there is less wasted space and open area between the terminating solar cell 660 of one module and the initial solar cell (not shown) of an adjacent module.
- integrated busbar-solar-cell-current collector 690 may include a supplementary carrier-film strip (not shown) at the edge 664 of the terminating solar cell 660 and running along the length of the side 662 disposed above and coupled to top carrier film 650 and the terminating busbar 680 to affix the terminating busbar 680 to the extended portions, for example, 670 x and 670 y .
- the integrated busbar-solar-cell-current collector 690 may include the top carrier film 650 extending over the top of the terminating busbar 680 and extended portions, for example, 670 x and 670 y , to affix the terminating busbar 680 to these extended portions.
- these latter two embodiments of the present invention provide a laminate including the terminating busbar 680 disposed between top carrier film 650 , or alternatively the supplementary carrier-film strip, and the supplementary isolation strip (not shown) along the edge 664 and side 662 of the terminating solar cell 660 .
- the top carrier film 650 is conducive to connecting the terminating busbar 680 without requiring solder to the plurality, itself, or to the extended portions, for example, 670 x and 670 y , of the plurality of integrated pairs 670 a & b , 670 c & c , 670 e & f , 670 g & h , 670 i and 670 l & m of electrically conductive, electrically parallel trace portions 670 a - m
- FIG. 7A a combined cross-sectional elevation and perspective view of a roll-to-roll, interconnect-assembly fabricator 700 A is shown.
- FIG. 7A shows the roll-to-roll, interconnect-assembly fabricator 700 A operationally configured to fabricate an interconnect assembly 720 .
- the roll-to-roll, interconnect-assembly fabricator 700 A includes an first unwinding spool 710 upon which the first roll of material 714 of the top carrier film 716 including the electrically insulating layer is mounted. As shown, a portion of the first roll of material 714 is unrolled. The unrolled portion of the top carrier film 716 including the electrically insulating layer passes to the right and is taken up on a take-up spool 718 upon which it is rewound as a third roll 722 of interconnect assembly 720 , after conductive-trace material 750 is provided from a dispenser 754 and is laid down onto the unrolled portion of the top carrier film 716 including the electrically insulating layer.
- the dispenser 754 of conductive-trace material 750 may be a spool of wire, or some other container providing conductive-trace material.
- the conductive-trace material 750 may be laid down onto the unrolled portion of the top carrier film 716 including the electrically insulating layer in an oscillatory motion, but without limitation to a strictly oscillatory motion, indicated by double-headed arrow 758 , to create a first plurality of electrically conductive portions configured both to collect current from a first solar cell and to interconnect electrically to a second solar cell such that solar-cell efficiency is substantially undiminished in an event that any one of the first plurality of electrically conductive portions is conductively impaired. As shown in FIG.
- a portion of the electrically conductive portions overhang one side of the top carrier film 716 to allow the electrically conductive portions of the trace to interconnect electrically to the second solar cell on the exposed top side of the trace, while the exposed bottom side of the trace, here shown as facing upward on the top carrier film 716 , allows the electrically conductive portions of the trace in contact with the top carrier film 716 to interconnect electrically to the first solar cell.
- the conductive-trace material 750 may be disposed in a serpentine pattern to create the plurality of electrically conductive portions configured both to collect current from the first solar cell and to interconnect electrically to the second solar cell.
- the arrows adjacent to the first unwinding spool 710 , and the take-up spool 718 indicate that these are rotating components of the roll-to-roll, interconnect-assembly fabricator 700 A; the first unwinding spool 710 , and the take-up spool 718 are shown rotating in clockwise direction, as indicated by the arrow-heads on the respective arrows adjacent to these components, to transport the unrolled portion of the first roll of material 714 from the first unwinding spool 710 on the left to the take-up spool 718 on the right.
- FIG. 7B a combined cross-sectional elevation and perspective view of a roll-to-roll, laminated-interconnect-assembly fabricator 700 B is shown.
- FIG. 7A shows the roll-to-roll, laminated-interconnect-assembly fabricator 700 B operationally configured to fabricate a laminated-interconnect assembly 740 .
- the roll-to-roll, laminated-interconnect-assembly fabricator 700 B first fabricates the interconnect assembly 720 shown on the left-hand side of FIG. 7B from the first roll of material 714 of the top carrier film 716 including the electrically insulating layer and from conductive-trace material 750 provided from dispenser 754 .
- the roll-to-roll, laminated-interconnect-assembly fabricator 700 B continues fabrication of the laminated-interconnect assembly 740 by applying a bottom carrier film 736 from a second roll 734 .
- the bottom carrier film 736 includes a carrier film selected from a group consisting of a second electrically insulating layer, a structural plastic layer, and a metallic layer, and is coupled to the conductive-trace material 750 and is disposed below a bottom portion of the conductive-trace material 750 .
- a supplementary isolation strip (not shown) of a third electrically insulating layer is added to the laminated-interconnect assembly 740 configured to allow interposition of the third electrically insulating layer between the bottom carrier film 736 and a top surface of the first solar cell to provide additional protection at an edge of the first solar cell and to prevent shorting out the solar cell in the event that the bottom carrier film 736 including the metallic layer should ride down the side of the first solar cell.
- the laminated-interconnect assembly 740 passes to the right-hand side of FIG. 7B and is taken up on the take-up spool 718 upon which it is wound as a fourth roll 742 of laminated-interconnect assembly 740 .
- the arrows adjacent to the first unwinding spool 710 , a second unwinding spool 730 and the take-up spool 718 indicate that these are rotating components of the roll-to-roll, laminated-interconnect-assembly fabricator 700 B; the first unwinding spool 710 , and the take-up spool 718 are shown rotating in clockwise direction, as indicated by the arrow-heads on the respective arrows adjacent to these components, to transport the unrolled portion of the first roll of material 714 from the first unwinding spool 710 on the left to the take-up spool 718 on the right.
- the second unwinding spool 730 , and the dispenser 754 are shown rotating in a counterclockwise direction and a clockwise direction, respectively, as indicated by the arrow-heads on the respective arrows adjacent to these components, as they release the bottom carrier layer 736 and the conductive-trace material 750 , respectively, in fabrication of the laminated-interconnect assembly 740 .
- the double-headed arrow 758 indicates the motion imparted to the conductive trace material by the roll-to-roll, laminated-interconnect-assembly fabricator 700 B creates a first plurality of electrically conductive portions configured both to collect current from a first solar cell and to interconnect electrically to a second solar cell such that solar-cell efficiency is substantially undiminished in an event that any one of the first plurality of electrically conductive portions is conductively impaired.
- a flow chart illustrates an embodiment of the present invention for a method for roll-to-roll fabrication of an interconnect assembly.
- a first carrier film including a first substantially transparent, electrically insulating layer is provided in roll form.
- a trace is provided from a dispenser of conductive-trace material.
- the dispenser may be a spool of wire or other container of conductive-trace material.
- a portion of the first carrier film including the first substantially transparent, electrically insulating layer is unrolled.
- the trace from the dispenser of conductive-trace material is laid down onto the portion of the first carrier film including the first substantially transparent, electrically insulating layer.
- the trace is configured as a first plurality of electrically conductive portions such that solar-cell efficiency is substantially undiminished in an event that any one of the first plurality of electrically conductive portions is conductively impaired.
- the portion of the first said first carrier film including the substantially transparent, electrically insulating layer is coupled to a top portion of the trace to provide an interconnect assembly.
- configuring the trace also includes: configuring the trace as a second plurality of paired trace portions; configuring a first portion of a paired portion of the second plurality of paired trace portions to allow both collecting current from a first solar cell and electrically interconnecting the first solar cell with a second solar cell; disposing proximately to the first portion, a second portion of the paired portion; and configuring the second portion to allow both collecting current from the first solar cell and electrically interconnecting the first solar cell with the second solar cell.
- configuring the trace may include disposing the trace in a serpentine pattern that allows for collecting current from the first solar cell and electrically interconnecting to the second solar cell.
- the method may also include: providing a second carrier film including a second electrically insulating layer; coupling the second carrier film including the second electrically insulating layer to a bottom portion of the trace; and configuring the second electrically insulating layer to allow forming an edge-protecting portion at an edge of the first solar cell.
- the method may include configuring the first substantially transparent, electrically insulating layer to allow forming a short-circuit-preventing portion at an edge of the second solar cell.
- a flow chart illustrates an embodiment of the present invention for a method of interconnecting two solar cells.
- a first solar cell and at least a second solar cell are provided.
- a combined applicable carrier film, interconnect assembly including a trace including a plurality of electrically conductive portions is provided.
- the plurality of electrically conductive portions of the trace is configured both to collect current from the first solar cell and to interconnect electrically with the second solar cell such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired.
- the combined applicable carrier film, interconnect assembly is applied and coupled to a light-facing side of the first solar cell.
- the combined applicable carrier film, interconnect assembly is applied and coupled to a back side of the second solar cell.
- the method also includes applying and coupling the combined applicable carrier film, interconnect assembly to the light-facing side of the first solar cell without requiring solder.
- the method may include applying and coupling the combined applicable carrier film, interconnect assembly to the back side of the second solar cell without requiring solder.
- the method includes applying and coupling the combined applicable carrier film, interconnect assembly to the light-facing side of the first solar cell such that a second electrically insulating layer of the applicable carrier film, interconnect assembly forms an edge-protecting portion at an edge of the first solar cell.
- the method also includes applying and coupling the combined applicable carrier film, interconnect assembly to the back side of the second solar cell such that a first substantially transparent, electrically insulating layer of the applicable carrier film, interconnect assembly forms a short-circuit-preventing portion at an edge of the second solar cell.
- the method may also include configuring the trace in a serpentine pattern that allows for collecting current from the first solar cell and electrically interconnecting to the second solar cell.
- the trace does not need to be used in conjunction with the afore-mentioned serpentine interconnect assembly approach, but could be used for other current collection and/or interconnection approaches used in solar cell technology.
- a trace including a conductive core with an overlying layer of nickel provides the unexpected result that when placed in contact with the TCO layer of a solar cell it suppresses current in the vicinity of short-circuit defects in the solar cell that might occur in the vicinity of the contact of the nickel layer of the trace with the TCO layer.
- the nickel increases local contact resistance which improves the ability of the solar cell to survive in the event of the formation of a defect, such as a shunt or a near shunt, located in the adjacent vicinity of the contact of the nickel layer of the trace with the TCO layer. If there is such a defect in the vicinity of the contact of the nickel layer of the trace with the TCO layer, the nickel reduces the tendency of the solar cell to pass increased current through the site of the defect, such as a shunt or a near shunt. Thus, the nickel acts as a localized resistor preventing run-away currents and high current densities in the small localized area associated with the site of the defect, such as a shunt or a near shunt.
- nickel in contrast, for example, to a low resistivity material such as silver, where the current density becomes so high at the location of the defect due to the high conductivity of silver that nearly almost all the current of the cell would be passed at the location of the defect causing a hot spot that would result in the melting of the silver with the formation of a hole in the solar cell filling with the silver migrating to the site of the defect to form a super-shunt.
- nickel does not readily migrate nor melt in the presence of elevated localized temperatures associated with the site of increased currents attending formation of the defect, such as a shunt or a near shunt.
- nickel tends to stay put so that if the site of a shunt occurs in the vicinity of a nickel coated or nickel trace, the nickel has less tendency to move to the location of the shunt thereby further exacerbating the drop of resistance at the shunt site.
- experimental results of the present invention indicate that a nickel trace, or a trace including a nickel layer, may actually increase its resistance due the possible formation of a nickel oxide such that the nickel trace, or the trace including the nickel layer, acts like a localized fuse limiting the current flow in the vicinity of the shunt site. In some cases, the efficiency of the solar cell has actually been observed to increase after formation of the shunt defect when the nickel trace, or the trace including the nickel layer, is used in contact with the TCO layer.
- the trace 520 for collecting current from a solar cell includes an electrically conductive line including the conductive core 520 A, and the overlying layer 520 B that limits current flow to a proximate shunt defect (not shown) in the solar cell, for example, first solar cell 510 .
- the proximate shunt defect may be proximately located in the vicinity of an electrical contact between the overlying layer 520 B of the electrically conductive line and the TCO layer 510 b of the solar cell, for example, first solar cell 510 .
- the overlying layer 520 B of the electrically conductive line of the trace 520 may further include an overlying layer 520 B composed of nickel.
- the conductive core 520 A of the electrically conductive line of the trace 520 may further include nickel.
- the conductive core 520 A may also include a material selected from a group consisting of copper, silver, aluminum, and elemental constituents and alloys having high electrical conductivity, which may be greater than the electrical conductivity of nickel.
- the TCO layer 510 b of the solar cell for example, first solar cell 510 , may include a conductive oxide selected from a group consisting of zinc oxide, aluminum zinc oxide and indium tin oxide.
- the absorber layer 510 a for example, absorber layer 112 of FIG.
- first solar cell 510 may include copper indium gallium diselenide (CIGS).
- CGS copper indium gallium diselenide
- semiconductors such as silicon, cadmium telluride, and chalcopyrite semiconductors, as well as other semiconductors, may be used as the absorber layer 510 a .
- an n-type layer, for example, n-type portion 112 b of absorber layer 112 of FIG. 1A , of the solar cell, for example, first solar cell 510 may be disposed on and electrically coupled to a p-type absorber layer, for example, absorber layer 112 of FIG.
- the solar cell for example, first solar cell 510
- the n-type layer for example, n-type portion 112 b of absorber layer 112 of FIG. 1A
- the n-type layer for example, n-type portion 112 b of absorber layer 112 of FIG. 1A
- the n-type layer for example, n-type portion 112 b of absorber layer 112 of FIG. 1A
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Abstract
An interconnect assembly. The interconnect assembly includes a trace that includes a plurality of electrically conductive portions. The plurality of electrically conductive portions is configured both to collect current from a first solar cell and to interconnect electrically to a second solar cell. In addition, the plurality of electrically conductive portions is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired.
Description
- This application is a continuation of U.S. patent application Ser. No. 13/850,976, filed Mar. 26, 2013, now allowed, which is a continuation of U.S. patent application Ser. No. 12/566,555 titled INTERCONNECT ASSEMBLY, filed Sep. 24, 2009, which is a continuation-in-part of U.S. patent application Ser. No. 12/052,476 titled INTERCONNECT ASSEMBLY, filed Mar. 20, 2008, now issued as U.S. Pat. No. 8,912,429. Each of these prior applications is incorporated herein by reference in its entirety for all purposes.
- Embodiments of the present invention relate generally to the field of photovoltaic technology.
- In the drive for renewable sources of energy, photovoltaic technology has assumed a preeminent position as a cheap renewable source of clean energy. In particular, solar cells based on the compound semiconductor copper indium gallium diselenide (CIGS) used as an absorber layer offer great promise for thin-film solar cells having high efficiency and low cost. Of comparable importance to the technology used to fabricate thin-film solar cells themselves, is the technology used to collect current from the solar cells and to interconnect one solar cell to another to form a solar-cell module.
- Just as the efficiency of thin-film solar cells is affected by parasitic series resistances, solar-cell modules fabricated from arrays of such thin-film solar cells are also impacted by parasitic series resistances. A significant challenge is the development of solar-cell, current collection and interconnection schemes that minimize the effects of such parasitic resistances. Moreover, the reliability of solar-cell modules based on such schemes is equally important as it determines the useful life of the solar-cell module and therefore its cost effectiveness and viability as a reliable alternative source of energy.
- Embodiments of the present invention include an interconnect assembly. The interconnect assembly includes a trace that includes a plurality of electrically conductive portions. The plurality of electrically conductive portions is configured both to collect current from a first solar cell and to interconnect electrically to a second solar cell. In addition, the plurality of electrically conductive portions is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired.
- The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the embodiments of the invention:
-
FIG. 1A is a cross-sectional elevation view of a layer structure of a solar cell, in accordance with an embodiment of the present invention. -
FIG. 1B is a schematic diagram of a model circuit of a solar cell, electrically connected to a load, in accordance with an embodiment of the present invention. -
FIG. 2 is a schematic diagram of a model circuit of a solar-cell module, electrically connected to a load, that shows the interconnection of solar cells in the solar-cell module, in accordance with an embodiment of the present invention. -
FIG. 3 is a schematic diagram of a model circuit of a solar-cell module, electrically connected to a load, that details model circuits of interconnect assemblies, in accordance with an embodiment of the present invention. -
FIG. 4A is a schematic diagram of a model circuit of an interconnect assembly for connecting two solar cells of a solar-cell module, in accordance with an embodiment of the present invention. -
FIG. 4B is a plan view of the interconnect assembly ofFIG. 4A that shows the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention. -
FIG. 4C is a cross-sectional, elevation view of the interconnect assembly ofFIG. 4B that shows the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention. -
FIG. 4D is a cross-sectional, elevation view of an alternative interconnect assembly forFIG. 4B that shows an edge-conforming interconnect assembly for the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention. -
FIG. 4E is a cross-sectional, elevation view of an alternative interconnect assembly forFIG. 4B that shows a shingled-solar-cell arrangement for the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention. -
FIG. 4F is a plan view of an alternative interconnect assembly forFIG. 4A that shows the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention. -
FIG. 4G is a plan view of the interconnect assembly ofFIG. 4A that shows the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention. -
FIG. 4H is a cross-sectional, elevation view of the interconnect assembly ofFIG. 4G that shows the physical interconnection of two solar cells in the solar-cell module, in accordance with an embodiment of the present invention. -
FIG. 5A is a plan view of the combined applicable carrier film, interconnect assembly that shows the physical arrangement of a trace with respect to a top carrier film and a bottom carrier film in the combined applicable carrier film, interconnect assembly, in accordance with an embodiment of the present invention. -
FIG. 5B is a plan view of the combined applicable carrier film, interconnect assembly that shows the physical arrangement of a trace with respect to a top carrier film and a bottom carrier film in the combined applicable carrier film, interconnect assembly, in accordance with another embodiment of the present invention. -
FIG. 5C is a cross-sectional schematic view of the physical arrangement of elements of an interconnect assembly connecting two solar cells in accordance with an embodiment of the present invention such as described and illustrated with reference toFIG. 5B . -
FIG. 5D is a cross-sectional, elevation view of the combined applicable carrier film, interconnect assembly ofFIG. 5A or 5B that shows the physical arrangement of a trace with respect to a top carrier film in the combined applicable carrier film, interconnect assembly prior to disposition on a solar cell, in accordance with embodiments of the present invention. -
FIG. 5E is a cross-sectional, elevation view of the interconnect assembly ofFIG. 5D that shows the physical arrangement of a trace with respect to a top carrier film in the combined applicable carrier film, interconnect assembly after disposition on a solar cell, in accordance with an embodiment of the present invention. -
FIG. 6A is a plan view of an integrated busbar-solar-cell-current collector that shows the physical interconnection of a terminating solar cell with a terminating busbar in the integrated busbar-solar-cell-current collector, in accordance with an embodiment of the present invention. -
FIG. 6B is a cross-sectional, elevation view of the integrated busbar-solar-cell-current collector ofFIG. 6A that shows the physical interconnection of the terminating solar cell with the terminating busbar in the integrated busbar-solar-cell-current collector, in accordance with an embodiment of the present invention. -
FIG. 7A is a combined cross-sectional elevation and perspective view of a roll-to-roll, interconnect-assembly fabricator for fabricating the interconnect assembly from a first roll of top carrier film and from a dispenser of conductive-trace material, in accordance with an embodiment of the present invention. -
FIG. 7B is a combined cross-sectional elevation and perspective view of a roll-to-roll, laminated-interconnect-assembly for fabricating a laminated-interconnect assembly from the first roll of top carrier film, from a second roll of bottom carrier film and from the dispenser of conductive-trace material, in accordance with an embodiment of the present invention. -
FIG. 8 is flow chart illustrating a method for roll-to-roll fabrication of an interconnect assembly, in accordance with an embodiment of the present invention. -
FIG. 9 is flow chart illustrating a method for interconnecting two solar cells, in accordance with an embodiment of the present invention. - The drawings referred to in this description should not be understood as being drawn to scale except if specifically noted.
- Reference will now be made in detail to the various embodiments of the present invention. While the invention will be described in conjunction with the various embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims.
- Furthermore, in the following description of embodiments of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it should be appreciated that embodiments of the present invention may be practiced without these specific details. In other instances, well known methods, procedures, and components have not been described in detail as not to unnecessarily obscure embodiments of the present invention.
- With reference to
FIG. 1A , in accordance with an embodiment of the present invention, a cross-sectional elevation view of a layer structure of asolar cell 100A is shown. Thesolar cell 100A includes ametallic substrate 104. In accordance with an embodiment of the present invention, an absorber layer 112 is disposed on themetallic substrate 104; the absorber layer 112 may include a layer of the material copper indium gallium diselenide (CIGS) having the chemical formula Cu(In1-xGax)Se2, where x may be a decimal less than one but greater than zero that determines the relative amounts of the constituents, indium, In, and gallium, Ga. Alternatively, semiconductors having the chalcopyrite crystal structure, for example, chemically homologous compounds with the compound CIGS having the chalcopyrite crystal structure, in which alternative elemental constituents are substituted for Cu, In, Ga, and/or Se, may be used as the absorber layer 112. Moreover, in embodiments of the present invention, it should be noted that semiconductors, such as silicon and cadmium telluride, as well as other semiconductors, may be used as the absorber layer 112. - As shown, the absorber layer 112 includes a p-
type portion 112 a and an n-type portion 112 b. As a result, a pn homojunction 112 c is produced in the absorber layer 112 that serves to separate charge carriers that are created by light incident on the absorber layer 112. To facilitate the efficient conversion of light energy to charge carriers in the absorber layer 112, the composition of the p-type portion 112 a of the absorber layer 112 may vary with depth to produce a graded band gap of the absorber layer 112. Alternatively, the absorber layer 112 may include only a p-type chalcopyrite semiconductor layer, such as a CIGS material layer, and a pn heterojunction may be produced between the absorber layer 112 and an n-type layer, such as a metal oxide, metal sulfide or metal selenide, disposed on its top surface in place of the n-type portion 112 b shown inFIG. 1A . However, embodiments of the present invention are not limited to pn junctions fabricated in the manner described above, but rather a generic pn junction produced either as a homojunction in a single semiconductor material, or alternatively a heterojunction between two different semiconductor materials, is within the spirit and scope of embodiments of the present invention. Moreover, in embodiments of the present invention, it should be noted that semiconductors, such as silicon and cadmium telluride, as well as other semiconductors, may be used as the absorber layer 112. - In accordance with an embodiment of the present invention, on the surface of the n-
type portion 112 b of the absorber layer 112, one or more transparent electrically conductive oxide (TCO) layers 116 are disposed, for example, to provide a means for collection of current from the absorber layer 112 for conduction to an external load. As used herein, it should be noted that the phrase “collection of current” refers to collecting current carriers of either sign, whether they be positively charged holes or negatively charged electrons; for the structure shown inFIG. 1A in which the TCO layer is disposed on the n-type portion 112 b, the current carriers collected under normal operating conditions are negatively charged electrons; but, embodiments of the present invention apply, without limitation thereto, to solar cell configurations where a p-type layer is disposed on an n-type absorber layer, in which case the current carriers collected may be positively charged holes. TheTCO layer 116 may include zinc oxide, ZnO, or alternatively a doped conductive oxide, such as aluminum zinc oxide (AZO), AlxZn1-xOy, and indium tin oxide (ITO), InxSn1-xOy, where the subscripts x and y indicate that the relative amount of the constituents may be varied. Alternatively, theTCO layer 116 may be composed of a plurality of conductive oxide layers. These TCO layer materials may be sputtered directly from an oxide target, or alternatively the TCO layer may be reactively sputtered in an oxygen atmosphere from a metallic target, such as zinc, Zn, Al—Zn alloy, or In—Sn alloy targets. For example, the zinc oxide may be deposited on the absorber layer 112 by sputtering from a zinc-oxide-containing target; alternatively, the zinc oxide may be deposited from a zinc-containing target in a reactive oxygen atmosphere in a reactive-sputtering process. The reactive-sputtering process may provide a means for doping the absorber layer 112 with an n-type dopant, such as zinc, Zn, or indium, In, to create a thin n-type portion 112 b, if the partial pressure of oxygen is initially reduced during the initial stages of sputtering a metallic target, such as zinc, Zn, or indium, In, and the layer structure of thesolar cell 100A is subsequently annealed to allow interdiffusion of the zinc, Zn, or indium, In, with CIGS material used as the absorber layer 112. Alternatively, sputtering a compound target, such as a metal oxide, metal sulfide or metal selenide, may also be used to provide the n-type layer, as described above, on the p-type portion 112 a of the absorber layer 112. - With further reference to
FIG. 1A , in accordance with the embodiment of the present invention, aconductive backing layer 108 may be disposed between the absorber layer 112 and themetallic substrate 104 to provide a diffusion barrier between the absorber layer 112 and themetallic substrate 104. Theconductive backing layer 108 may include molybdenum, Mo, or other suitable metallic layer having a low propensity for interdiffusion with an absorber layer 112, such as one composed of CIGS material, as well as a low diffusion coefficient for constituents of the substrate. Moreover, theconductive backing layer 108 may provide other functions in addition to, or independent of, the diffusion-barrier function, for example, a light-reflecting function, for example, as a light-reflecting layer, to enhance the efficiency of the solar cell, as well as other functions. The embodiments recited above for theconductive backing layer 108 should not be construed as limiting the function of theconductive backing layer 108 to only those recited, as other functions of theconductive backing layer 108 are within the spirit and scope of embodiments of the present invention, as well. - With reference now to
FIG. 1B , in accordance with an embodiment of the present invention, a schematic diagram of amodel circuit 100B of a solar cell that is electrically connected to a load is shown. Themodel circuit 100B of the solar cell includes acurrent source 158 that generates a photocurrent, iL. As shown inFIG. 1A , thecurrent source 158 is such as to produce counterclockwise electrical current, or equivalently an clockwise electron-flow, flowing around each of the loops of the circuit shown; embodiments of the present invention also apply, without limitation thereto, to solar-cell circuits in which the electrical current flows in a clockwise direction, or equivalently electrons flow in a counterclockwise direction. The photocurrent, iL, is produced when a plurality of incident photons, light particles, of which oneexample photon 154 with energy, hν, is shown, produce electron-hole pairs in the absorber layer 112 and these electron-hole pairs are separated by the pn homojunction 112 c, or in the alternative, by a pn heterojunction as described above. It should be appreciated that the energy, hν, of each incident photon of the plurality of photons should exceed the band-gap energy, Eg, that separates the valence band from the conduction band of the absorber layer 112 to produce such electron-hole pairs, which result in the photocurrent, iL. - The
model circuit 100B of the solar cell further includes adiode 162, which corresponds to recombination currents, primarily at the pn homojunction 112 c, that are shunted away from the connected load. As shown inFIG. 1B , the diode is shown having a polarity consistent with electrical current flowing counterclockwise, or equivalently electron-flow clockwise, around the loops of the circuit shown; embodiments of the present invention apply, without limitation thereto, to a solar cell in which the diode of the model circuit has the opposite polarity in which electrical current flows clockwise, or equivalently electron-flow flows counterclockwise, around the loops of the circuit shown. In addition, themodel circuit 100B of the solar cell includes two parasitic resistances corresponding to ashunt resistor 166 with shunt resistance, RSh, and to aseries resistor 170 with series resistance, RS. The solar cell may be connected to a load represented by aload resistor 180 with load resistance, RL. Thus, the circuit elements of the solar cell include thecurrent source 158, thediode 162 and theshunt resistor 166 connected across thecurrent source 158, and theseries resistor 170 connected in series with theload resistor 180 across thecurrent source 158, as shown. As theshunt resistor 166, like thediode 162, are connected across thecurrent source 158, these two circuit elements are associated with internal electrical currents within the solar cell shunted away from useful application to the load. As theseries resistor 170 connected in series with theload resistor 180 are connected across thecurrent source 158, theseries resistor 170 is associated with internal resistance of the solar cell that limits the electrical current to the load. - With further reference to
FIG. 1B , it should be recognized that the shunt resistance may be associated with surface leakage currents that follow paths at free surfaces that cross the pn homojunction 112 c; free surfaces are usually found at the edges of the solar cell along the side walls of the device that define its lateral dimensions; such free surfaces may also be found at discontinuities in the absorber layer 112 that extend past the pn homojunction 112 c. The shunt resistance may also be associated with shunt defects which may be present that shunt electrical current away from the load. A small value of the shunt resistance, RSh, is undesirable as it lowers the open circuit voltage, VOC, of the solar cell, which directly affects the efficiency of the solar cell. Moreover, it should also be recognized that the series resistance, RS, is associated with: the contact resistance between the p-type portion 112 a and theconductive backing layer 108, the bulk resistance of the p-type portion 112 a, the bulk resistance of the n-type portion 112 b, the contact resistance between the n-type portion 112 b andTCO layer 116, and other components, such as conductive leads, and connections in series with the load. These latter sources of series resistance, conductive leads, and connections in series with the load, are germane to embodiments of the present invention as interconnect assemblies, which is subsequently described. A large value of the series resistance, RS, is undesirable as it lowers the short circuit current, ISC, of the solar cell, which also directly affects the efficiency of the solar cell. - With reference now to
FIG. 2 , in accordance with an embodiment of the present invention, a schematic diagram of amodel circuit 200 of a solar-cell module 204 that is coupled to a load is shown. The load is represented by aload resistor 208 with load resistance, RL, as shown. The solar-cell module 204 of themodel circuit 200 includes a plurality of solar cells: a firstsolar cell 210 including acurrent source 210 a that generates a photocurrent, iL1, produced by example photon 214 with energy, hν1, adiode 210 b and ashunt resistor 210 c with shunt resistance, RSh1; a secondsolar cell 230 including acurrent source 230 a that generates a photocurrent, iL2, produced byexample photon 234 with energy, hν2, adiode 230 b and ashunt resistor 230 c with shunt resistance, RSh2; and, a terminatingsolar cell 260 including acurrent source 260 a that generates a photocurrent, iL3, produced byexample photon 264 with energy, hνn, adiode 260 b and ashunt resistor 260 c with shunt resistance, RShn. Parasitic series internal resistances of the respectivesolar cells cell module 204 of themodel circuit 200 connected in series with thesolar cells load resistor 208. - As shown in
FIGS. 2 and 3 , the current sources are such as to produce counterclockwise electrical current, or equivalently an clockwise electron-flow, flowing around each of the loops of the circuit shown; embodiments of the present invention also apply, without limitation thereto, to solar-cell circuits in which the electrical current flows in a clockwise direction, or equivalently electrons flow in a counterclockwise direction. Similarly, as shown inFIGS. 2 and 3 , the diode is shown having a polarity consistent with electrical current flowing counterclockwise, or equivalently electron-flow clockwise, around the loops of the circuit shown; embodiments of the present invention apply, without limitation thereto, to a solar cell in which the diode of the model circuit has the opposite polarity in which electrical current flows clockwise, or equivalently electron-flow flows counterclockwise, around the loops of the circuit shown. - With further reference to
FIG. 2 , in accordance with an embodiment of the present invention, the series resistors with series resistances RS1 and RS2 correspond to interconnectassemblies assembly 220 is shown configured both to collect current from the firstsolar cell 210 and to interconnect electrically to the secondsolar cell 230. Series resistor with series resistance, RSn, corresponds to an integrated solar-cell,current collector 270. Theellipsis 250 indicates additional solar cells and interconnect assemblies (not shown) coupled in alternating pairs in series inmodel circuit 200 that make up the solar-cell module 204. Also, in series with thesolar cells first busbar 284 and a terminatingbusbar 280 with series resistances RB1 and RB2, respectively, that carry the electrical current generated by solar-cell module 204 to theload resistor 208. The series resistor with resistance RSn, corresponding to the integrated solar-cell,current collector 270, and RB2, corresponding to the terminatingbusbar 280, in combination correspond to a integrated busbar-solar-cell-current collector 290 coupling the terminatingsolar cell 260 with theload resistor 208. In addition, series resistor with resistance RS1, corresponding to interconnectassembly 220, and firstsolar cell 210 in combination correspond to a combined solar-cell,interconnect assembly 294. - As shown in
FIG. 2 and as used herein, it should be noted that the phrases “to collect current,” “collecting current” and “current collector” refer to collecting, transferring, and/or transmitting current carriers of either sign, whether they be positively charged holes or negatively charged electrons; for the structures shown inFIGS. 1A-B , 2, 3, 4A-F, 5A-C and 6A-B, in which an interconnect assembly is disposed above and electrically coupled to an n-type portion of the solar cell, the current carriers collected under normal operating conditions are negatively charged electrons. Moreover, embodiments of the present invention apply, without limitation thereto, to solar cell configurations where a p-type layer is disposed on an n-type absorber layer, in which case the current carriers collected may be positively charged holes, as would be the case for solar cells modeled by diodes and current sources of opposite polarity to those ofFIGS. 1A-B , 2, 3, 4A-F, 5A-C and 6A-B. Therefore, in accordance with embodiments of the present invention, a current collector and associated interconnect assembly that collects current may, without limitation thereto, collect, transfer, and/or transmit charges associated with an electrical current, and/or charges associated with an electron-flow, as for either polarity of the diodes and current sources described herein, and thus for either configuration of a solar cell with an n-type layer disposed on and electrically coupled to a p-type absorber layer or a p-type layer disposed on and electrically coupled to an n-type absorber layer, as well as other solar cell configurations. - With further reference to
FIG. 2 , in accordance with an embodiment of the present invention, the series resistances of theinterconnect assemblies current collector 270, and the interconnect assemblies included inellipsis 250 can have a substantial net series resistance in themodel circuit 200 of the solar-cell module 204, unless the series resistances of theinterconnect assemblies current collector 270, and the interconnect assemblies included inellipsis 250 are made small. If a large plurality of solar cells are connected in series, the short circuit current of the solar-cell module, ISCM, may be reduced, which also directly affects the solar-cell-module efficiency analogous to the manner in which solar-cell efficiency is reduced by a parasitic series resistance, RS, as described above with reference toFIG. 1 . Embodiments of the present invention provide for diminishing the series resistances of theinterconnect assemblies current collector 270, and the interconnect assemblies included inellipsis 250. - With reference now to
FIG. 3 , in accordance with embodiments of the present invention, a schematic diagram of amodel circuit 300 of a solar-cell module 304 is shown that illustrates embodiments of the present invention such that the series resistances of theinterconnect assemblies current collector 370, and the interconnect assemblies included inellipsis 350 are made small. The solar-cell module 304 is coupled to a load represented by aload resistor 308 with load resistance, RL, as shown. The solar-cell module 304 of themodel circuit 300 includes a plurality of solar cells: a firstsolar cell 310 including acurrent source 310 a that generates a photocurrent, iL1, produced by example photon 314 with energy, hν1, adiode 310 b and ashunt resistor 310 c with shunt resistance, RSh1; a secondsolar cell 330 including acurrent source 330 a that generates a photocurrent, iL2, produced byexample photon 334 with energy, hν2, adiode 330 b and ashunt resistor 330 c with shunt resistance, RSh2; and, a terminatingsolar cell 360 including acurrent source 360 a that generates a photocurrent, iL3, produced byexample photon 364 with energy, hνn, adiode 360 b and ashunt resistor 360 c with shunt resistance, RShn. - With further reference to
FIG. 3 , in accordance with an embodiment of the present invention, theinterconnect assemblies current collector 370, with respective equivalent series resistances RS1, RS2 and RSn are shown disposed in the solar-cell module 304 of themodel circuit 300 connected in series with thesolar cells load resistor 308. Theellipsis 350 indicates additional solar cells and interconnect assemblies (not shown) coupled in alternating pairs in series inmodel circuit 300 that make up the solar-cell module 304. Also, in series with thesolar cells busbar 380 with series resistances RB1 and RB2, respectively, that carry the electrical current generated by solar-cell module 304 to theload resistor 308. The integrated solar-cell,current collector 370 with resistance RSn, and the series resistor with series resistance RB2, corresponding to the terminatingbusbar 380, in combination correspond to an integrated busbar-solar-cell-current collector 390 coupling the terminatingsolar cell 360 with theload resistor 308. In addition,interconnect assembly 320 with resistance, RS2, andsolar cell 310 in combination correspond to a combined solar-cell,interconnect assembly 394. - With further reference to
FIG. 3 , in accordance with embodiments of the present invention, theinterconnect assembly 320 includes a trace including a plurality of electrically conductive portions, identified withresistors ellipsis 320 i indicating additional resistors (not shown). It should be noted that although the plurality of electrically conductive portions of the trace are modeled here as discrete resistors the interconnection withsolar cell 330 is considerably more complicated involving the distributed resistance in the TCO layer of the solar cell, which has been omitted for the sake of elucidating functional features of embodiments of the present invention. Therefore, it should be understood that embodiments of the present invention may also include, without limitation thereto, the effects of such distributed resistances on the trace. The plurality of electrically conductive portions, without limitation thereto, identified withresistors solar cell 310 and to interconnect electrically to the secondsolar cell 330. The plurality of electrically conductive portions, identified withresistors solar cell 310 and the secondsolar cell 330 the plurality of electrically conductive portions are connected electrically in parallel between the firstsolar cell 310 and the secondsolar cell 330. - Thus, in accordance with embodiments of the present invention, the plurality of electrically conductive portions is configured such that equivalent series resistance, RS1, of the
interconnect assembly 320 including the parallel network ofresistors solar cell 310 with the secondsolar cell 330, the equivalent series resistance, RS1, of theinterconnect assembly 320, is given approximately, omitting the effects of distributed resistances at the interconnects with the first and secondsolar cells solar cell 310 to the secondsolar cell 330, with theinterconnect assembly 320, the series resistance, RS1, of theinterconnect assembly 320 can be reduced lowering the effective series resistance between solar cells in the solar-cell module 304 improving the solar-cell-module efficiency. - Moreover, in accordance with embodiments of the present invention, the configuration of the plurality of electrically conductive portions due to this parallel arrangement of electrically conductive portions between the first
solar cell 310 and the secondsolar cell 330 provides a redundancy of electrical current carrying capacity between interconnected solar cells should one of the plurality of electrically conductive portions become damaged, or its reliability become impaired. Thus, embodiments of the present invention provide that the plurality of electrically conductive portions is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired, because the loss of electrical current through any one electrically conductive portion will be compensated for by the plurality of other parallel electrically conductive portions coupling the firstsolar cell 310 with the secondsolar cell 330. It should be noted that as used herein the phrase, “substantially undiminished,” with respect to solar-cell efficiency means that the solar-cell efficiency is not reduced below an acceptable level of productive performance. - With further reference to
FIG. 3 , in accordance with embodiments of the present invention, theinterconnect assembly 340 includes a trace including a plurality of electrically conductive portions identified withresistors ellipsis 340 i indicating additional resistors (not shown). The plurality of electrically conductive portions, without limitation thereto, identified withresistors solar cell 330 and to interconnect electrically to a second solar cell, in this case a next adjacent one of the plurality of solar cells represented byellipsis 350. From this example, it should be clear that for embodiments of the present invention a first solar cell and a second solar cell refer, without limitation thereto, to just two adjacent solar cells configured in series in the solar-cell module, and need not be limited to a solar cell located first in line of a series of solar cells in a solar-cell module, nor a solar cell located second in line of a series of solar cells in a solar-cell module. Theresistors solar cell 330 and the second solar cell, in this case the next adjacent solar cell of the plurality of solar cells represented byellipsis 350, theresistors solar cell 330 and the second solar cell, the next adjacent solar cell of the plurality of solar cells represented byellipsis 350. - Thus, in accordance with embodiments of the present invention, the plurality of electrically conductive portions is configured such that series resistance, RS2, of the
interconnect assembly 340 including the parallel network ofresistors interconnect assembly 340 can be reduced lowering the effective series resistance between solar cells in the solar-cell module improving the solar-cell-module efficiency of the solar-cell module 304. Moreover, the plurality of electrically conductive portions, identified withresistors - With further reference to
FIG. 3 , in accordance with embodiments of the present invention, the combined solar-cell,interconnect assembly 394 includes the firstsolar cell 310 and theinterconnect assembly 320; theinterconnect assembly 320 includes a trace disposed above a light-facing side of the firstsolar cell 310, the trace further including a plurality of electrically conductive portions, identified withresistors ellipsis 320 i indicating additional resistors (not shown). All electrically conductive portions of the plurality of electrically conductive portions, without limitation thereto, identified withresistors solar cell 310 and to interconnect electrically to the secondsolar cell 330. In addition, the plurality of electrically conductive portions, identified withresistors resistors solar cell 330. - With further reference to
FIG. 3 , in accordance with embodiments of the present invention, the integrated busbar-solar-cell-current collector 390 includes the terminatingbusbar 380 and the integrated solar-cell,current collector 370. The integrated solar-cell,current collector 370 includes a trace including a plurality of electrically conductive portions, identified withresistors resistors solar cell 310 and to interconnect electrically to the terminatingbusbar 380. Theresistors solar cell 360 and the terminatingbusbar 380 series resistor with series resistance, RB2. Thus, the plurality of electrically conductive portions is configured such that series resistance, RSn, of theinterconnect assembly 340 including the parallel network ofresistors - In accordance with embodiments of the present invention, the integrated solar-cell,
current collector 370 includes a plurality of integrated pairs of electrically conductive, electrically parallel trace portions.Resistors solar cell 360. For example, one such pair of the plurality of integrated pairs of electrically conductive, electrically parallel trace portions is pair ofresistors 370 a and 370 b connected electrically together as an integral unit over the terminatingsolar cell 360, as shown. The plurality of integrated pairs of electrically conductive, electrically parallel trace portions are configured both to collect current from the terminatingsolar cell 360 and to interconnect electrically to the terminatingbusbar 380. Moreover, the plurality of integrated pairs of electrically conductive, electrically parallel trace portions is configured such that solar-cell efficiency is substantially undiminished in an event that any one electrically conductive, electrically parallel trace portion, for example, either one, but not both, of theresistors 370 a and 370 b of the integral pair, of the plurality of integrated pairs of electrically conductive, electrically parallel trace portions is conductively impaired. - With further reference to
FIG. 3 , in accordance with embodiments of the present invention, the solar-cell module 304 includes the firstsolar cell 310, at least the secondsolar cell 330 and theinterconnect assembly 320 disposed above a light-facing side of an absorber layer of the firstsolar cell 310. Theinterconnect assembly 320 includes a trace comprising a plurality of electrically conductive portions, identified withresistors ellipsis 320 i indicating additional resistors (not shown). The plurality of electrically conductive portions is configured both to collect current from the firstsolar cell 310 and to interconnect electrically to the secondsolar cell 330. The plurality of electrically conductive portions is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired. - With reference now to
FIGS. 4A, 4B and 4C , in accordance with embodiments of the present invention, a schematic diagram of amodel circuit 400A of aninterconnect assembly 420 connecting a firstsolar cell 410 to a secondsolar cell 430 of a solar-cell module 404 is shown. Theinterconnect assembly 420 includes a trace including a plurality of electrically conductive portions, identified withresistors ellipsis 420 i indicating additional resistors (not shown). The plurality of electrically conductive portions, without limitation thereto, identified withresistors solar cell 410 and to interconnect electrically to the secondsolar cell 430. The plurality of electrically conductive portions, identified withresistors solar cell 410 and the secondsolar cell 430, the plurality of electrically conductive portions are connected electrically in parallel between the firstsolar cell 410 and the secondsolar cell 430. The plurality of electrically conductive portions is configured such that equivalent series resistance, RS1, of theinterconnect assembly 420 including the parallel network ofresistors solar cell 410 to the secondsolar cell 430, with theinterconnect assembly 420, the series resistance, RS1, of theinterconnect assembly 420 can be reduced lowering the effective series resistance between solar cells in the solar-cell module 404 improving the solar-cell-module efficiency. - Moreover, in accordance with embodiments of the present invention, the configuration of the plurality of electrically conductive portions due to this parallel arrangement of electrically conductive portions between the first
solar cell 410 and the secondsolar cell 430 provides a redundancy of electrical current carrying capacity between interconnected solar cells should any one of the plurality of electrically conductive portions become damaged, or its reliability become impaired. Thus, embodiments of the present invention provide that the plurality of electrically conductive portions is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired, because the loss of electrical current through any one electrically conductive portion will be compensated for by the plurality of the unimpaired parallel electrically conductive portions coupling the firstsolar cell 410 with the secondsolar cell 430. It should be noted that as used herein the phrase, “substantially undiminished,” with respect to solar-cell efficiency means that the solar-cell efficiency is not reduced below an acceptable level of productive performance. In addition, in accordance with embodiments of the present invention, the plurality of electrically conductive portions may be configured in pairs of electrically conductive portions, for example, identified withresistors - With further reference to
FIGS. 4B and 4C , in accordance with embodiments of the present invention, aplan view 400B of theinterconnect assembly 420 ofFIG. 4A is shown that details the physical interconnection of twosolar cells cell module 404. The solar-cell module 404 includes the firstsolar cell 410, at least the secondsolar cell 430 and theinterconnect assembly 420 disposed above a light-facingside 416 of the absorber layer of the firstsolar cell 410. Theinterconnect assembly 420 includes a trace comprising a plurality of electricallyconductive portions resistors FIG. 400A , where the ellipsis of 420 i indicates additional electrically conductive portions (not shown). The plurality of electricallyconductive portions solar cell 410 and to interconnect electrically to the secondsolar cell 430. The plurality of electricallyconductive portions conductive portions - With further reference to
FIG. 4B , in accordance with embodiments of the present invention, the detailed configuration of the plurality of electricallyconductive portions conductive portions first portion 420 a of the plurality of electricallyconductive portions solar cell 410 and to interconnect electrically to the secondsolar cell 430 and asecond portion 420 b of the plurality of electricallyconductive portions solar cell 410 and to interconnect electrically to the secondsolar cell 430. Thefirst portion 420 a includes afirst end 420 p distal from the secondsolar cell 430. Also, thesecond portion 420 b includes asecond end 420 q distal from the secondsolar cell 430. Thesecond portion 420 b is disposed proximately to thefirst portion 420 a and electrically connected to thefirst portion 420 a such that the firstdistal end 420 p is electrically connected to the seconddistal end 420 q, for example, atfirst junction 420 r, or by a linking portion, such that thesecond portion 420 b is configured electrically in parallel to thefirst portion 420 a when configured to interconnect to the secondsolar cell 430. - With further reference to
FIG. 4B , in accordance with embodiments of the present invention, the plurality of electricallyconductive portions second portion 420 b including athird end 420 s distal from the firstsolar cell 410 and athird portion 420 c of the plurality of electricallyconductive portions solar cell 410 and to interconnect electrically to the secondsolar cell 430. Thethird portion 420 c includes afourth end 420 t distal from the firstsolar cell 410. Thethird portion 420 c is disposed proximately to thesecond portion 420 b and electrically connected to thesecond portion 420 b such that the thirddistal end 420 s is electrically connected to the fourthdistal end 420 t, for example, atsecond junction 420 u, or by a linking portion, such that thethird portion 420 c is configured electrically in parallel to thesecond portion 420 b when configured to interconnect with the firstsolar cell 430. - With further reference to
FIGS. 4B and 4C , in accordance with embodiments of the present invention, it should be noted that the nature of the parallel connection between electrically conductive portions interconnecting a first solar cell and a second solar cell is such that, for distal ends of electrically conductive portions not directly joined together, without limitation thereto, the metallic substrate of a second solar cell and a TCO layer of the first solar cell may provide the necessary electrical coupling. For example, distal ends 420 v and 420 s are electrically coupled through a low resistance connection through ametallic substrate 430 c of secondsolar cell 430. Similarly, for example, distal ends 420 w and 420 q are electrically coupled through the low resistance connection through theTCO layer 410 b of firstsolar cell 410. - With further reference to
FIG. 4B , in accordance with embodiments of the present invention, an open-circuit defect 440 is shown such thatsecond portion 420 b is conductively impaired.FIG. 4B illustrates the manner in which the plurality of electricallyconductive portions conductive portions second portion 420 b. Anarrow 448 indicates the nominal electron-flow through athird portion 420 c of the plurality of electricallyconductive portions circuit defect 440. In the absence of open-circuit defect 440, an electron-flow indicated byarrow 448 would normally flow through any one electrically conductive portion of the plurality of electricallyconductive portions second portion 420 b. However, when the open-circuit defect 440 is present, this electron-flow divides into two portions shown byarrows 442 and 444:arrow 442 corresponding to that portion of the normal electron-flow flowing to the right along thesecond portion 420 b to the secondsolar cell 430, andarrow 444 corresponding to that portion of the normal electron-flow flowing to the left along thesecond portion 420 b to thefirst portion 420 a and then to the right along thefirst portion 420 a to the secondsolar cell 430. Thus, the net electron-flow represented byarrow 446 flowing to the right along thefirst portion 420 a is consequently larger than what would normally flow to the right along thefirst portion 420 a to the secondsolar cell 430 in the absence of the open-circuit defect 440. - It should be noted that open-
circuit defect 440 is for illustration purposes only and that embodiments of the present invention compensate for other types of defects in an electrically conductive portion, in general, such as, without limitation to: a delamination of an electrically conductive portion from the firstsolar cell 410, corrosion of an electrically conductive portion, and even complete loss of an electrically conductive portion. In accordance with embodiments of the present invention, in the event a defect completely conductively impairs an electrically conductive portion, the physical spacing between adjacent electrically conductive portions, identified with double-headedarrow 449, may be chosen such that solar-cell efficiency is substantially undiminished. Nevertheless, embodiments of the present invention embrace, without limitation thereto, other physical spacings between adjacent electrically conductive portions in the event defects are less severe than those causing a complete loss of one of the electrically conductive portions. - With further reference to
FIG. 4B , in accordance with embodiments of the present invention, the plurality of electricallyconductive portions conductive portions interconnect assembly 420 is configured to collect current from the firstsolar cell 410 and to interconnect electrically to the secondsolar cell 430, as shown. - With further reference to
FIG. 4C , in accordance with embodiments of the present invention, a cross-sectional,elevation view 400C of theinterconnect assembly 420 is shown that further details the physical interconnection of twosolar cells cell module 404.Projections FIGS. 4B and 4C , and coincident with the ends of the plurality of electricallyconductive portions plan view 400B ofFIG. 4B and features in the cross-sectional,elevation view 400C ofFIG. 4C . Also, it should be noted that although the solar-cell module 404 is shown withseparation 472 between the firstsolar cell 410 and the secondsolar cell 430, there need not besuch separation 472 between the firstsolar cell 410 and the secondsolar cell 430. As shown inFIGS. 4B and 4C , a combined solar-cell,interconnect assembly 494 includes the firstsolar cell 410 and theinterconnect assembly 420. Theinterconnect assembly 420 includes the trace disposed above the light-facingside 416 of the firstsolar cell 410, the trace further including the plurality of electricallyconductive portions conductive portions solar cell 410 and to interconnect electrically to the secondsolar cell 430. In addition, the plurality of electricallyconductive portions conductive portions conductive portions solar cell 430. The firstsolar cell 410 of the combined solar-cell,interconnect assembly 494 may include ametallic substrate 410 c and anabsorber layer 410 a. Theabsorber layer 410 a of the firstsolar cell 410 may include copper indium gallium diselenide (CIGS). Alternatively, other semiconductors having the chalcopyrite crystal structure, for example, chemically homologous compounds with the compound CIGS having the chalcopyrite crystal structure, in which alternative elemental constituents are substituted for Cu, In, Ga, and/or Se, may be used as theabsorber layer 410 a. Moreover, in embodiments of the present invention, it should be noted that semiconductors, such as silicon and cadmium telluride, as well as other semiconductors, may be used as theabsorber layer 410 a. - With further reference to
FIG. 4C , in accordance with embodiments of the present invention, the plurality of electricallyconductive portions interconnect assembly 494 further includes thefirst portion 420 a of the plurality of electricallyconductive portions solar cell 410 and thesecond portion 420 b of the plurality of electricallyconductive portions solar cell 410. Thefirst portion 420 a includes thefirst end 420 p distal from anedge 414 of the firstsolar cell 410. Thesecond portion 420 b includes thesecond end 420 q distal from theedge 414 of the firstsolar cell 410. Thesecond portion 420 b is disposed proximately to thefirst portion 420 a and electrically connected to thefirst portion 420 a such that the firstdistal end 420 p is electrically connected to the seconddistal end 420 q such that thesecond portion 420 b is configured electrically in parallel to thefirst portion 420 a when configured to interconnect to the secondsolar cell 430. - With further reference to
FIG. 4C , in accordance with embodiments of the present invention, theinterconnect assembly 420 further includes atop carrier film 450. Thetop carrier film 450 includes a first substantially transparent, electrically insulating layer coupled to the trace and disposed above a top portion of the trace. The first substantially transparent, electrically insulating layer allows for forming a short-circuit-preventingportion 454 at anedge 434 of the secondsolar cell 430. The first substantially transparent, electrically insulating layer allows for forming the short-circuit-preventingportion 454 at theedge 434 of the secondsolar cell 430 to prevent thefirst portion 420 a from short circuiting anabsorber layer 430 a of the secondsolar cell 430 in the event that thefirst portion 420 a buckles and rides up aside 432 of secondsolar cell 430. Theedge 434 is located at the intersection of theside 432 of the secondsolar cell 430 and aback side 438 of the secondsolar cell 430 that couples with the plurality of electricallyconductive portions first portion 420 a as shown. The secondsolar cell 430 may include theabsorber layer 430 a, aTCO layer 430 b, and themetallic substrate 430 c; a backing layer (not shown) may also be disposed between theabsorber layer 430 a and themetallic substrate 430 c. Above a light-facingside 436 of the secondsolar cell 430, an integrated busbar-solar-cell-current collector (not shown inFIG. 4C , but which is shown inFIGS. 6A and 6B ) may be disposed and coupled to the secondsolar cell 430 to provide interconnection with a load (not shown). Alternatively, above the light-facingside 436 of the secondsolar cell 430, another interconnect assembly (not shown) may be disposed and coupled to the secondsolar cell 430 to provide interconnection with additional solar-cells (not shown) in the solar-cell module 404. - With further reference to
FIG. 4C , in accordance with embodiments of the present invention, theinterconnect assembly 420 further includes abottom carrier film 460. Thebottom carrier film 460 may include a second electrically insulating layer coupled to the trace and disposed below a bottom portion of the trace. Alternatively, Thebottom carrier film 460 may include a carrier film selected from a group consisting of a second electrically insulating layer, a structural plastic layer, and a metallic layer, and is coupled to the trace and is disposed below a bottom portion of the trace. The second electrically insulating layer allows for forming an edge-protectingportion 464 at theedge 414 of the firstsolar cell 410. Alternatively, a supplementary isolation strip (not shown) of a third electrically insulating layer may be disposed between thebottom carrier film 460 and thefirst portion 420 a of the plurality of electricallyconductive portions bottom carrier film 460 and theedge 414, to provide additional protection at theedge 414. The supplementary isolation strip may be as wide as 5 millimeters (mm) in the direction of the double-headed arrow showing theseparation 472, and may extend along the full length of aside 412 of the firstsolar cell 410. Theedge 414 is located at the intersection of theside 412 of the firstsolar cell 410 and a light-facingside 416 of the firstsolar cell 410 that couples with the plurality of electricallyconductive portions first portion 420 a as shown. The firstsolar cell 410 may include theabsorber layer 410 a, theTCO layer 410 b, and themetallic substrate 410 c; a backing layer (not shown) may also be disposed between theabsorber layer 410 a and themetallic substrate 410 c. Below aback side 418 of the firstsolar cell 410, a first busbar (not shown) may be disposed and coupled to the firstsolar cell 410 to provide interconnection with a load (not shown). Alternatively, below theback side 418 of the firstsolar cell 410, another interconnect assembly (not shown) may be disposed and coupled to the firstsolar cell 410 to provide interconnection with additional solar-cells (not shown) in the solar-cell module 404. - With reference now to
FIGS. 4D and 4E , in accordance with embodiments of the present invention, cross-sectional, elevation views 400D and 400E, respectively, of two alternative interconnect assemblies that minimize the separation 472 (seeFIG. 4B ) between the firstsolar cell 410 and the secondsolar cell 430 to improve the solar-cell-module efficiency of the solar-cell module 404 are shown. In both examples shown inFIGS. 4D and 4E , theside 412 of the firstsolar cell 410 essentially coincides with theside 432 of the secondsolar cell 430. It should be noted that as used herein the phrase, “essentially coincides,” with respect to theside 412 of the firstsolar cell 410 and theside 432 of the secondsolar cell 430 means that there is little or noseparation 472 between the firstsolar cell 410 and the secondsolar cell 430, and little or no overlap of the firstsolar cell 410 with the secondsolar cell 430 so that there is less wasted space and open area between thesolar cells cell module 404 resulting in improved solar-cell-module efficiency.FIG. 4D shows an edge-conforming interconnect assembly for the physical interconnection of the twosolar cells cell module 404.FIG. 4E shows a shingled-solar-cell arrangement for the physical interconnection of the twosolar cells cell module 404. For both the edge-conforming interconnect assembly ofFIG. 4D and the shingled-solar-cell arrangement ofFIG. 4E , theinterconnect assembly 420 further includes thebottom carrier film 460. Thebottom carrier film 460 includes a second electrically insulating layer coupled to the trace and disposed below a bottom portion of the trace. Alternatively, Thebottom carrier film 460 may include a carrier film selected from a group consisting of a second electrically insulating layer, a structural plastic layer, and a metallic layer, and is coupled to the trace and is disposed below a bottom portion of the trace. The second electrically insulating layer allows for forming the edge-protectingportion 464 at theedge 414 of the firstsolar cell 410. In the case of the edge-conforming interconnect assembly shown inFIG. 4D , thebottom carrier film 460 and thefirst portion 420 a of theinterconnect assembly 420 may be relatively flexible and compliant allowing them to wrap around theedge 414 and down theside 412 of the firstsolar cell 410, as shown. Theedge 414 is located at the intersection of theside 412 of the firstsolar cell 410 and the light-facingside 416 of the firstsolar cell 410 that couples with the plurality of electricallyconductive portions first portion 420 a as shown. The firstsolar cell 410 may include theabsorber layer 410 a, aTCO layer 410 b, and themetallic substrate 410 c; a backing layer (not shown) may also be disposed between theabsorber layer 410 a and themetallic substrate 410 c. Below theback side 418 of the firstsolar cell 410, another interconnect assembly (not shown) or first busbar (not shown) may be disposed and coupled to the firstsolar cell 410 as described above forFIG. 4C . If an additional solar cell (not shown) is interconnected to theback side 418 of the firstsolar cell 410 as in the shingled-solar-cell arrangement ofFIG. 4E , the firstsolar cell 410 would be pitched upward at its left-hand side and interconnected to another interconnect assembly similar to the manner in which the secondsolar cell 430 is shown interconnected withsolar cell 410 atside 412 inFIG. 4E . - With further reference to
FIGS. 4D and 4E , in accordance with embodiments of the present invention, theinterconnect assembly 420 further includes thetop carrier film 450. Thetop carrier film 450 includes a first substantially transparent, electrically insulating layer coupled to the trace and disposed above a top portion of the trace. The first substantially transparent, electrically insulating layer allows for forming the short-circuit-preventingportion 454 at theedge 434 of the secondsolar cell 430 to prevent thefirst portion 420 a from short circuiting theabsorber layer 430 a of the secondsolar cell 430 in the event that thefirst portion 420 a rides up theside 432 of secondsolar cell 430. Theedge 434 is located at the intersection of theside 432 of the secondsolar cell 430 and theback side 438 of the secondsolar cell 430 that couples with the plurality of electricallyconductive portions first portion 420 a as shown. In the case of the edge-conforming interconnect assembly shown inFIG. 4D , thetop carrier film 450 may be relatively flexible and compliant allowing it to follow the conformation of thebottom carrier film 460 and thefirst portion 420 a of theinterconnect assembly 420 underlying it that wrap around theedge 414 and down theside 412 of the firstsolar cell 410, as shown. The secondsolar cell 430 may include theabsorber layer 430 a, theTCO layer 430 b, and themetallic substrate 430 c; a backing layer (not shown) may also be disposed between theabsorber layer 430 a and themetallic substrate 430 c. Also, in the case of the edge-conforming interconnect assembly, theabsorber layer 430 a,TCO layer 430 b, andmetallic substrate 430 c of the secondsolar cell 430 may be relatively flexible and compliant allowing them to follow the conformation of theunderlying interconnect assembly 420 that wraps around theedge 414 and down theside 412 of the firstsolar cell 410. Above the light-facingside 436 of the secondsolar cell 430, an integrated busbar-solar-cell-current collector (not shown inFIG. 4C , but which is shown inFIGS. 6A and 6B ), or alternatively another interconnect assembly (not shown), may be disposed on and coupled to the secondsolar cell 430, as described above forFIG. 4C . - With reference now to
FIG. 4F , in accordance with embodiments of the present invention, aplan view 400F of an alternative interconnect assembly for theinterconnect assembly 420 ofFIG. 4A is shown that details the physical interconnection of twosolar cells cell module 404. The solar-cell module 404 includes the firstsolar cell 410, at least the secondsolar cell 430 and theinterconnect assembly 420 disposed above the light-facingside 416 of the absorber layer of the firstsolar cell 410. Theedges solar cells separation 472 as shown inFIG. 4F ; or alternatively, theedges solar cells FIGS. 4D and 4E . Theinterconnect assembly 420 includes a trace comprising a plurality of electricallyconductive portions resistors FIG. 400A , where the ellipsis of 420 i indicates additional electrically conductive portions (not shown). The plurality of electricallyconductive portions solar cell 410 and to interconnect electrically to the secondsolar cell 430. The plurality of electricallyconductive portions conductive portions - With further reference to
FIG. 4F , in accordance with embodiments of the present invention, the detailed configuration of the plurality of electricallyconductive portions conductive portions FIG. 4F . The plurality of electricallyconductive portions TCO layer 410 b of the firstsolar cell 410 at distal ends of the trace disposed over the firstsolar cell 410, for example, firstdistal end 420 p offirst portion 420 a and seconddistal end 420 q ofsecond portion 420 b by portions of theTCO layer 410 b of the firstsolar cell 410 that lie in between the distal ends 420 p and 420 q. In like fashion, the distal ends 420 w and 420 q are electrically coupled through the low resistance connection through theTCO layer 410 b of firstsolar cell 410. Similarly, the plurality of electricallyconductive portions metallic substrate 430 c, or intervening backing layer (not shown), of the firstsolar cell 430 at distal ends of the trace disposed under the secondsolar cell 430, for example, thirddistal end 420 s ofsecond portion 420 b and fourthdistal end 420 t ofthird portion 420 c by portions of themetallic substrate 430 c of the secondsolar cell 430 that lie in between the distal ends 420 s and 420 t. In like fashion, the distal ends 420 v and 420 s are electrically coupled through a low resistance connection through themetallic substrate 430 c of secondsolar cell 430. - With further reference to
FIG. 4F , in accordance with embodiments of the present invention, the open-circuit defect 440 is shown such thatsecond portion 420 b is conductively impaired.FIG. 4F illustrates the manner in which the plurality of electricallyconductive portions conductive portions second portion 420 b. Anarrow 480 indicates the nominal electron-flow through an m-th portion 420 m of the plurality of electricallyconductive portions circuit defect 440. In the absence of open-circuit defect 440, an electron-flow indicated byarrow 480 would normally flow through any one electrically conductive portion of the plurality of electricallyconductive portions second portion 420 b. However, when the open-circuit defect 440 is present, portions of this electron-flow are lost to adjacent electricallyconductive portions arrows arrow 482 corresponds to that portion of the normal electron-flow flowing to the right along thesecond portion 420 b to the secondsolar cell 430, andarrow 484 b corresponds to that portion of the normal electron-flow that would bridge the open-circuit defect 440 by flowing through the higher resistance path of theTCO layer 410 b bridging across the two portions ofsecond portion 420 b on either side of the open-circuit defect 440. Thus, the net electron-flow represented byarrow 486 flowing to the right along thefirst portion 420 a is consequently larger than what would normally flow to the right along thefirst portion 420 a to the secondsolar cell 430 in the absence of the open-circuit defect 440; and, the net electron-flow represented byarrow 488 flowing to the right along thethird portion 420 c is consequently larger than what would normally flow to the right along thethird portion 420 c to the secondsolar cell 430 in the absence of the open-circuit defect 440. - Moreover, in the case of the alternative interconnect assembly depicted in
FIG. 4F , as stated before for the interconnect assembly depicted inFIG. 4B , it should again be noted that open-circuit defect 440 is for illustration purposes only and that embodiments of the present invention compensate for other types of defects in an electrically conductive portion, in general, such as, without limitation to: a delamination of an electrically conductive portion from the firstsolar cell 410, corrosion of an electrically conductive portion, and even complete loss of an electrically conductive portion. In accordance with embodiments of the present invention, in the event a defect completely conductively impairs an electrically conductive portion, the physical spacing between adjacent electrically conductive portions, identified with double-headedarrow 449, may be chosen such that solar-cell efficiency is substantially undiminished. Nevertheless, embodiments of the present invention embrace, without limitation thereto, other physical spacings between adjacent electrically conductive portions in the event defects are less severe than those causing a complete loss of one of the electrically conductive portions. - With further reference to
FIGS. 4G and 4H , in accordance with embodiments of the present invention, aplan view 400G of theinterconnect assembly 420 ofFIG. 4A is shown that details the physical interconnection of twosolar cells cell module 404. The solar-cell module 404 includes the firstsolar cell 410, at least the secondsolar cell 430 and theinterconnect assembly 420 disposed above a light-facingside 416 of the absorber layer of the firstsolar cell 410. Theinterconnect assembly 420 includes a trace comprising a plurality of electricallyconductive portions resistors FIG. 400A , where the ellipsis of 420 i indicates additional electrically conductive portions (not shown). The plurality of electricallyconductive portions solar cell 410 and to interconnect electrically to the secondsolar cell 430. The plurality of electricallyconductive portions conductive portions - With further reference to
FIG. 4G , in accordance with embodiments of the present invention, the detailed configuration of the plurality of electricallyconductive portions conductive portions first portion 420 a of the plurality of electricallyconductive portions solar cell 410 and to interconnect electrically to the secondsolar cell 430 and asecond portion 420 b of the plurality of electricallyconductive portions solar cell 410 and to interconnect electrically to the secondsolar cell 430. Thefirst portion 420 a includes afirst end 420 p distal from the secondsolar cell 430. Also, thesecond portion 420 b includes asecond end 420 q distal from the secondsolar cell 430. Thesecond portion 420 b is disposed proximately to thefirst portion 420 a and electrically connected to thefirst portion 420 a such that the firstdistal end 420 p is electrically connected to the seconddistal end 420 q, for example, atfirst junction 420 r, or by a linking portion, such that thesecond portion 420 b is configured electrically in parallel to thefirst portion 420 a when configured to interconnect to the secondsolar cell 430. - With further reference to
FIG. 4G , in accordance with embodiments of the present invention, the plurality of electricallyconductive portions second portion 420 b including athird end 420 s distal from the firstsolar cell 410 and athird portion 420 c of the plurality of electricallyconductive portions solar cell 410 and to interconnect electrically to the secondsolar cell 430. Thethird portion 420 c includes afourth end 420 t distal from the firstsolar cell 410. Thethird portion 420 c is disposed proximately to thesecond portion 420 b and electrically connected to thesecond portion 420 b such that the thirddistal end 420 s is electrically connected to the fourthdistal end 420 t, for example, atsecond junction 420 u, or by a linking portion, such that thethird portion 420 c is configured electrically in parallel to thesecond portion 420 b when configured to interconnect with the firstsolar cell 430. - With further reference to
FIGS. 4G and 4H , in accordance with embodiments of the present invention, it should be noted that the nature of the parallel connection between electrically conductive portions interconnecting a first solar cell and a second solar cell is such that, for distal ends of electrically conductive portions not directly joined together, without limitation thereto, the metallic substrate of a second solar cell and a TCO layer of the first solar cell may provide the necessary electrical coupling. For example, distal ends 420 v and 420 s are electrically coupled through a low resistance connection through ametallic substrate 430 c of secondsolar cell 430. Similarly, for example, distal ends 420 w and 420 q are electrically coupled through the low resistance connection through theTCO layer 410 b of firstsolar cell 410. - With further reference to
FIG. 4G , in accordance with embodiments of the present invention, an open-circuit defect 440 is shown such thatsecond portion 420 b is conductively impaired.FIG. 4G illustrates the manner in which the plurality of electricallyconductive portions conductive portions second portion 420 b. Anarrow 448 indicates the nominal electron-flow through athird portion 420 c of the plurality of electricallyconductive portions circuit defect 440. In the absence of open-circuit defect 440, an electron-flow indicated byarrow 448 would normally flow through any one electrically conductive portion of the plurality of electricallyconductive portions second portion 420 b. However, when the open-circuit defect 440 is present, this electron-flow divides into two portions shown byarrows 442 and 444:arrow 442 corresponding to that portion of the normal electron-flow flowing to the right along thesecond portion 420 b to the secondsolar cell 430, andarrow 444 corresponding to that portion of the normal electron-flow flowing to the left along thesecond portion 420 b to thefirst portion 420 a and then to the right along thefirst portion 420 a to the secondsolar cell 430. Thus, the net electron-flow represented byarrow 446 flowing to the right along thefirst portion 420 a is consequently larger than what would normally flow to the right along thefirst portion 420 a to the secondsolar cell 430 in the absence of the open-circuit defect 440. - It should be noted that open-
circuit defect 440 is for illustration purposes only and that embodiments of the present invention compensate for other types of defects in an electrically conductive portion, in general, such as, without limitation to: a delamination of an electrically conductive portion from the firstsolar cell 410, corrosion of an electrically conductive portion, and even complete loss of an electrically conductive portion. In accordance with embodiments of the present invention, in the event a defect completely conductively impairs an electrically conductive portion, the physical spacing between adjacent electrically conductive portions, identified with double-headedarrow 449, may be chosen such that solar-cell efficiency is substantially undiminished. Nevertheless, embodiments of the present invention embrace, without limitation thereto, other physical spacings between adjacent electrically conductive portions in the event defects are less severe than those causing a complete loss of one of the electrically conductive portions. - With further reference to
FIG. 4G , in accordance with embodiments of the present invention, the plurality of electricallyconductive portions conductive portions interconnect assembly 420 is configured to collect current from the firstsolar cell 410 and to interconnect electrically to the secondsolar cell 430, as shown. - With further reference to
FIG. 4H , in accordance with embodiments of the present invention, a cross-sectional,elevation view 400H of theinterconnect assembly 420 is shown that further details the physical interconnection of twosolar cells cell module 404.Projections FIGS. 4G and 4H , and coincident with the ends of the plurality of electricallyconductive portions plan view 400G ofFIG. 4G and features in the cross-sectional,elevation view 400H ofFIG. 4H . Also, it should be noted that although the solar-cell module 404 is shown withseparation 472 between the firstsolar cell 410 and the secondsolar cell 430, there need not besuch separation 472 between the firstsolar cell 410 and the secondsolar cell 430. In some embodiments, the separation will be less than that depicted in the figures. In some embodiments, the cells may overlap. - As shown in
FIGS. 4G and 4H , a combined solar-cell,interconnect assembly 494 includes the firstsolar cell 410 and theinterconnect assembly 420. Theinterconnect assembly 420 includes the trace disposed above the light-facingside 416 of the firstsolar cell 410, the trace further including the plurality of electricallyconductive portions conductive portions solar cell 410 and to interconnect electrically to the secondsolar cell 430. In addition, the plurality of electricallyconductive portions conductive portions conductive portions solar cell 430. The firstsolar cell 410 of the combined solar-cell,interconnect assembly 494 may include ametallic substrate 410 c and anabsorber layer 410 a. Theabsorber layer 410 a of the firstsolar cell 410 may include copper indium gallium diselenide (CIGS). Alternatively, other semiconductors having the chalcopyrite crystal structure, for example, chemically homologous compounds with the compound CIGS having the chalcopyrite crystal structure, in which alternative elemental constituents are substituted for Cu, In, Ga, and/or Se, may be used as theabsorber layer 410 a. Moreover, in embodiments of the present invention, it should be noted that semiconductors, such as silicon and cadmium telluride, as well as other semiconductors, may be used as theabsorber layer 410 a. - With further reference to
FIG. 4H , in accordance with embodiments of the present invention, the plurality of electricallyconductive portions interconnect assembly 494 further includes thefirst portion 420 a of the plurality of electricallyconductive portions solar cell 410 and thesecond portion 420 b of the plurality of electricallyconductive portions solar cell 410. Thefirst portion 420 a includes thefirst end 420 p distal from anedge 414 of the firstsolar cell 410. Thesecond portion 420 b includes thesecond end 420 q distal from theedge 414 of the firstsolar cell 410. Thesecond portion 420 b is disposed proximately to thefirst portion 420 a and electrically connected to thefirst portion 420 a such that the firstdistal end 420 p is electrically connected to the seconddistal end 420 q such that thesecond portion 420 b is configured electrically in parallel to thefirst portion 420 a when configured to interconnect to the secondsolar cell 430. - With further reference to
FIG. 4H , in accordance with embodiments of the present invention, theinterconnect assembly 420 further includes top andbottom carrier films top carrier film 450 includes a first substantially transparent, electrically insulating layer coupled to thetrace 420 and disposed above atop portion 420 x of thetrace 420. The first substantially transparent, electrically insulating layer terminates a small distance short of theedge 412 of thefirst cell 410. Thebottom carrier film 460 may include a second electrically insulating layer coupled to thetrace 420 and disposed below a bottom portion of thetrace 420 a. Alternatively, thebottom carrier film 460 may include a carrier film selected from a group consisting of a second electrically insulating layer, a structural plastic layer, and a metallic layer, and is coupled to the trace and is disposed below a bottom portion of the trace. The second electrically insulating layer allows for forming an edge-protectingportion 464 at theedge 414 of the firstsolar cell 410. Alternatively, a supplementary isolation strip (not shown) of a third electrically insulating layer may be disposed between thebottom carrier film 460 and thefirst portion 420 a of the plurality of electricallyconductive portions bottom carrier film 460 and theedge 414, to provide additional protection at theedge 414. The supplementary isolation strip may be as wide as 5 millimeters (mm) in the direction of the double-headed arrow showing theseparation 472, and may extend along the full length of aside 412 of the firstsolar cell 410. Theedge 414 is located at the intersection of theside 412 of the firstsolar cell 410 and a light-facingside 416 of the firstsolar cell 410 that couples with the plurality of electricallyconductive portions first portion 420 a as shown. - The first
solar cell 410 may include theabsorber layer 410 a, theTCO layer 410 b, and themetallic substrate 410 c; a backing layer (not shown) may also be disposed between theabsorber layer 410 a and themetallic substrate 410 c. Below aback side 418 of the firstsolar cell 410, a first busbar (not shown) may be disposed and coupled to the firstsolar cell 410 to provide interconnection with a load (not shown). Alternatively, below theback side 418 of the firstsolar cell 410, another interconnect assembly (not shown) may be disposed and coupled to the firstsolar cell 410 to provide interconnection with additional solar-cells (not shown) in the solar-cell module 404. - The second
solar cell 430 may include theabsorber layer 430 a, aTCO layer 430 b, and themetallic substrate 430 c; a backing layer (not shown) may also be disposed between theabsorber layer 430 a and themetallic substrate 430 c. Above a light-facingside 436 of the secondsolar cell 430, an integrated busbar-solar-cell-current collector (not shown inFIG. 4H , but which is shown inFIGS. 6A and 6B ) may be disposed and coupled to the secondsolar cell 430 to provide interconnection with a load (not shown). Alternatively, above the light-facingside 436 of the secondsolar cell 430, another interconnect assembly (not shown) may be disposed and coupled to the secondsolar cell 430 to provide interconnection with additional solar-cells (not shown) in the solar-cell module 404. - With reference now to
FIG. 5A , in accordance with embodiments of the present invention, aplan view 500A of the combined applicable carrier film,interconnect assembly 504 is shown.FIG. 5A shows the physical arrangement of atrace 520 with respect to atop carrier film 550 and abottom carrier film 560 in the combined applicable carrier film,interconnect assembly 504. The combined applicable carrier film,interconnect assembly 504 includes thetop carrier film 550 and thetrace 520 including a plurality of electricallyconductive portions conductive portions 520 a through 520 m is configured both to collect current from a first solar cell 510 (shown inFIG. 5D ) and to interconnect electrically to a second solar cell (not shown). As shown inFIG. 5A , the plurality of electricallyconductive portions 520 a through 520 m run over the top of the firstsolar cell 510 on the left and over anedge 514 of the firstsolar cell 510 to the right under anedge 534 of, and underneath, the second solar cell (not shown). Thetop carrier film 550 includes a first substantially transparent, electrically insulating layer 550A (shown inFIG. 5B ). The plurality of electricallyconductive portions 520 a through 520 m is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electricallyconductive portions 520 a through 520 m is conductively impaired. It should be noted that as used herein the phrase, “substantially transparent,” with respect to a substantially transparent, electrically insulating layer means that light passes through the substantially transparent, electrically insulating layer with negligible absorption. The first substantially transparent, electrically insulatinglayer 550 a is coupled to thetrace 520 and disposed above a top portion of the trace 520 (shown inFIG. 5B ) as indicated by the dashed portions of thetrace 520 on the left ofFIG. 5A . - With reference now to
FIG. 5B , in accordance with embodiments of the present invention, aplan view 500B of the combined applicable carrier film,interconnect assembly 504 is shown.FIG. 5B shows the physical arrangement of atrace 520 with respect to atop carrier film 550 and abottom carrier film 560 in the combined applicable carrier film,interconnect assembly 504. The combined applicable carrier film,interconnect assembly 504 includes thetop carrier film 550 and thetrace 520 including a plurality of electricallyconductive portions conductive portions 520 a through 520 m is configured both to collect current from a first solar cell 510 (shown inFIG. 5E ) and to interconnect electrically to a second solar cell (not shown). As shown inFIG. 5B , the plurality of electricallyconductive portions 520 a through 520 m run over the top of the firstsolar cell 510 on the left and over anedge 514 of the firstsolar cell 510 to the right under anedge 534 of, and underneath, the second solar cell (not shown). Thetop carrier film 550 includes a first substantially transparent, electrically insulatinglayer 550 a (shown inFIG. 5D ). The plurality of electricallyconductive portions 520 a through 520 m is configured such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electricallyconductive portions 520 a through 520 m is conductively impaired. It should be noted that as used herein the phrase, “substantially transparent,” with respect to a substantially transparent, electrically insulating layer means that light passes through the substantially transparent, electrically insulating layer with negligible absorption. The first substantially transparent, electrically insulatinglayer 550 a is coupled to thetrace 520 and disposed above a top portion of the trace 520 (shown inFIG. 5D ) as indicated by the dashed portions of thetrace 520 on the left ofFIG. 5B . -
FIG. 5C provides a further illustration, in cross-section, of a specific embodiment of the present invention in accordance with that described with reference toFIG. 5B . The figure shows aspects of the interconnection arrangement of two solar cells. The firstsolar cell 570 can be constructed as previously described herein and include a CIGSthin film 572 on astainless steel substrate 574. The secondsolar cell 580 can have the same construction as thefirst cell 570, again including a CIGSthin film 582 on astainless steel substrate 584. The twocells small gap 599, generally as small a gap as possible, for example about 1-2 mm, between their respectiveclosest edges - The cells are interconnected by an
interconnect 590 that includes top and bottom carrier films (polymer decals) 592 and 594 and aconductive wire 596. In specific embodiments, the wire can be about 34 gauge and the decals can be composed of a layer of about 2 mil thick PET between layers of about 2 mil thick Surlyn adhesive. Thedecals wire 596 are arranged so that a portion of thewire 596 is exposed for electrical contact with atop side 573 of thefirst cell 570 and thebottom side 583 of the secondsolar cell 580. Thetop decal 592 covers the top of thewire 596 and extends from afirst end 597 of thewire 596 over the firstsolar cell 570 almost to theedge 575 of the firstsolar cell 570. Thebottom decal 594 covers the bottom of thewire 596, slightly overlaps thefirst decal 592 in extent, and extends to asecond end 598 of thewire 596 under the secondsolar cell 580. - With reference now to
FIGS. 5D and 5E , in accordance with embodiments of the present invention, a cross-sectional, elevation view of the combined applicable carrier film,interconnect assembly 504 ofFIG. 5A or 5B is shown. As shown inFIGS. 5D and 5E , the cross-section of the view is taken along a cut parallel to theedge 514 of the firstsolar cell 510. The cross-sectional, elevation view ofFIG. 5D shows the physical arrangement of thetrace 520 with respect to thetop carrier film 550 in the combined applicable carrier film,interconnect assembly 504 prior to disposition on the firstsolar cell 510. On the other hand, the cross-sectional, elevation view ofFIG. 5E shows the physical arrangement of thetrace 520 with respect to thetop carrier film 550 and the firstsolar cell 510 of the combined applicable carrier film,interconnect assembly 504 after it couples with the firstsolar cell 510. Thetop carrier film 550 and thetrace 520 are configured for applying to a light-facing side of the firstsolar cell 510 both to collect current from the firstsolar cell 510 and to interconnect electrically to the second solar cell (not shown). The firstsolar cell 510 may include anabsorber layer 510 a, aTCO layer 510 b, and ametallic substrate 510 c; the backing layer (not shown) may also be disposed between theabsorber layer 510 a and themetallic substrate 510 c. The first substantially transparent, electrically insulatinglayer 550 a holds thetrace 520 down in contact with the firstsolar cell 510 and allows for forming a short-circuit-preventing portion at an edge of the second solar cell (not shown). Thetop carrier film 550 further includes a first substantially transparent,adhesive medium 550 b coupling thetrace 520 to the substantially transparent, electrically insulatinglayer 550 a. As shown inFIG. 5D , prior to disposition on the firstsolar cell 510, thetop carrier film 550 lies relatively flat across the top portion of thetrace 520, for example, as for the conformational state of thetop carrier film 550 immediately after roll-to-roll fabrication of the combined applicable carrier film,interconnect assembly 504. In contrast, after disposition on the firstsolar cell 510, thetop carrier film 550 conforms to the top portion of thetrace 520, as shown inFIG. 5D . The first substantially transparent,adhesive medium 550 b allows for coupling thetrace 520 to the firstsolar cell 510 without requiring solder. The first substantially transparent, electrically insulatinglayer 550 a may include a structural plastic material, such as polyethylene terephthalate (PET). In accordance with embodiments of the present invention, a first substantially transparent, adhesive medium such as first substantially transparent,adhesive medium 550 b may be included, without limitation thereto, in a top carrier film of: the combined applicable carrier film,interconnect assembly 504, theinterconnect assembly 320, the integrated busbar-solar-cell-current collector 690 (seeFIG. 6B ), the combined solar-cell,interconnect assembly 494, or theinterconnect assembly 420 of the solar-cell module 404. - With further reference to
FIGS. 5A, 5B and 5D , in accordance with embodiments of the present invention, the combined applicable carrier film,interconnect assembly 504 further includes thebottom carrier film 560. Thebottom carrier film 560 includes a second electrically insulating layer, like 550 a, coupled to thetrace 520 and disposed below a bottom portion of thetrace 520, as indicated by the solid-line portions of thetrace 520 on the right ofFIG. 5A . Alternatively, thebottom carrier film 560 may include a carrier film selected from a group consisting of a second electrically insulating layer, a structural plastic layer, and a metallic layer, and is coupled to thetrace 520 and is disposed below a bottom portion of thetrace 520. The second electrically insulating layer, like 550 a, holds thetrace 520 down in contact with a back side of the second solar cell (not shown) and allows for forming an edge-protecting portion at theedge 514 of the firstsolar cell 510. Thebottom carrier film 560 further includes a second adhesive medium, like 550 b, coupling the trace to the second electrically insulating layer, like 550 a. The second adhesive medium, like 550 b, allows for coupling thetrace 520 to the back side of the second solar cell (not shown) without requiring solder. The second electrically insulating layer, like 550 a, includes a structural plastic material, such as PET. In accordance with embodiments of the present invention, a second adhesive medium, like 550 b, may be included, without limitation thereto, in a bottom carrier film of: the combined applicable carrier film,interconnect assembly 504, theinterconnect assembly 320, the combined solar-cell,interconnect assembly 494, or theinterconnect assembly 420 of the solar-cell module 404. - With further reference to
FIGS. 5A and 5B , in accordance with embodiments of the present invention, thetrace 520 may be disposed in a serpentine pattern that allows for collecting current from the first solar cell 510 (shown inFIG. 5D ) and electrically interconnecting to the second solar cell (not shown). It should be noted that neither the firstsolar cell 510 nor the second solar cell (not shown) are shown inFIG. 5A or 5B so as not to obscure the structure of the combined applicable carrier film,interconnect assembly 504. As shown inFIG. 5A , the combined applicable carrier film,interconnect assembly 504 includes thetrace 520 including the plurality of electricallyconductive portions 520 a through 520 m that may run in a serpentine pattern back and forth between the firstsolar cell 510 and the second solar cell (not shown). The serpentine pattern is such that adjacent electrically conductive portions of the plurality of electricallyconductive portions 520 a through 520 m are configured in pairs of adjacent electrically conductive portions: 520 a and 520 b, 520 c and 520 d, 520 e and 520 f, etc. The pairs of adjacent electrically conductive portions may be configured in a regular repeating pattern of equally spaced adjacent electrically conductive portions. Thetrace 520 including the plurality of electricallyconductive portions 520 a through 520 m is disposed between thetop carrier film 550 disposed above a top portion of thetrace 520 and thebottom carrier film 560 disposed below a bottom portion of thetrace 520. The first substantially transparent, electrically insulatinglayer 550 a oftop carrier film 550 and the second electrically insulating layer, or alternatively, structural plastic layer or metallic layer, ofbottom carrier film 560 are coupled to thetrace 520 with a first substantially transparent,adhesive medium 550 b and second adhesive medium which also serve to couple thetrace 520 to the firstsolar cell 510, which may be located on the left, and the second solar cell, which may be located on the right. - In the space between the two solar cells in the embodiment depicted in
FIG. 5A , between theedge 514 of the first solar cell and theedge 534 of the second solar cell, the trace is sandwiched between the twocarrier films carrier films respective edges edge 514 of the first solar cell, and a short-circuit-preventing portion at theedge 534 of the second solar cell, from thetrace 520 that crosses theedges - In the space between the two solar cells in the embodiment depicted in
FIG. 5B , between theedge 514 of the first solar cell and theedge 534 of the second solar cell, the trace is carried bybottom carrier film 560; the top carrier film terminates just short of theedge 514 of the firstsolar cell 510. In this way, thebottom carrier film 560 prevents contact between thetrace 520 and theedge 514 of the first solar cell. In this embodiment, there is no need to prevent contact between thetrace 520 and theedge 534 of the second solar cell, since the edge is not electrically conductive. - With further reference to
FIGS. 5B and 5E , in accordance with embodiments of the present invention, thetrace 520 may further include an electrically conductive line including aconductive core 520A with at least oneoverlying layer 520B. In one embodiment of the present invention, the electrically conductive line may include theconductive core 520A including a material having greater conductivity than nickel, for example, copper, with anoverlying nickel layer 520B. In another embodiment of the present invention, electrically conductive line may include theconductive core 520A including nickel without theoverlying layer 520B. The electrically conductive line may also be selected from a group consisting of a copper conductive core clad with a silver cladding, a copper conductive core clad with a nickel coating further clad with a silver cladding and an aluminum conductive core clad with a silver cladding. - With further reference to
FIGS. 5B and 5E , in accordance with embodiments of the present invention, thetrace 520 for collecting current from a solar cell, for example the firstsolar cell 510, may include an electrically conductive line including theconductive core 520A, and theoverlying layer 520B that limits current flow to a proximate shunt defect (not shown) in the solar cell. The proximate shunt defect may be proximately located in the vicinity of an electrical contact between theoverlying layer 520B of the electrically conductive line and theTCO layer 510 b of the solar cell, for example, firstsolar cell 510. Theoverlying layer 520B of the electrically conductive line of thetrace 520 may further include anoverlying layer 520B composed of nickel. Theconductive core 520A of the electrically conductive line of thetrace 520 may further include nickel. Theconductive core 520A may also include a material selected from a group consisting of copper, silver, aluminum, and elemental constituents and alloys having high electrical conductivity, which may be greater than the electrical conductivity of nickel. TheTCO layer 510 b of the solar cell, for example firstsolar cell 510, may include a conductive oxide selected from a group consisting of zinc oxide, aluminum zinc oxide and indium tin oxide. In addition, theabsorber layer 510 a, for example, absorber layer 112 ofFIG. 1A , of the solar cell, for example, firstsolar cell 510, may include copper indium gallium diselenide (CIGS). Alternatively, in embodiments of the present invention, it should be noted that semiconductors, such as silicon, cadmium telluride, and chalcopyrite semiconductors, as well as other semiconductors, may be used as theabsorber layer 510 a. Moreover, an n-type layer, for example, n-type portion 112 b of absorber layer 112 ofFIG. 1A , of the solar cell, for example, firstsolar cell 510, may be disposed on and electrically coupled to a p-type absorber layer, for example, absorber layer 112 ofFIG. 1A , of the solar cell, for example, firstsolar cell 510, and the n-type layer, for example, n-type portion 112 b of absorber layer 112 ofFIG. 1A , may be selected from a group consisting of a metal oxide, a metal sulfide and a metal selenide. - Although the
trace 520 is shown as having a circular cross-section having a point-like contact with a solar cell, for example, with theTCO layer 510 b, or, without limitation thereto, to a top surface, of the firstsolar cell 510, embodiments of the present inventions include, without limitation thereto, other cross-sectional profiles of thetrace 520, such as a profile including a flattened top portion and a flattened bottom portion, so as to increase the contact area between thetrace 520 and a solar cell with which it makes contact. For example, a flattened bottom portion oftrace 520 increases the contact area with the light-facing side of the firstsolar cell 510; on the other hand, a flattened top portion oftrace 520 increases the contact area with a back side of an adjacent solar cell to which the plurality of electricallyconductive portions 520 a through 520 m of thetrace 520 interconnects. In accordance with embodiments of the present invention, a trace, such astrace 520, may be included, without limitation thereto, in: the combined applicable carrier film,interconnect assembly 504, theinterconnect assembly 320, the integrated busbar-solar-cell-current collector 690 (seeFIG. 6B ), the combined solar-cell,interconnect assembly 494, or theinterconnect assembly 420 of the solar-cell module 404. - With reference now to
FIG. 6A , in accordance with embodiments of the present invention, aplan view 600A of an integrated busbar-solar-cell-current collector 690 is shown.FIG. 6A shows the physical interconnection of a terminatingsolar cell 660 with a terminatingbusbar 680 of the integrated busbar-solar-cell-current collector 690. The integrated busbar-solar-cell-current collector 690 includes the terminatingbusbar 680 and an integrated solar-cell, current collector 670. The integrated solar-cell, current collector 670 includes a plurality of integrated pairs 670 a&b, 670 c&d, 670 e&f, 670 g&h, and 670 l&m and 670 i, the ellipsis indicating additional integrated pairs (not shown), of electrically conductive, electrically parallel trace portions 670 a-m. Throughout the following, the respective integrated pairs: 670 a and 670 b, 670 c and 670 d, 670 e and 670 f, 670 g and 670 h, and 670 l and 670 m, are referred to respectively as: 670 a&b, 670 c&d, 670 e&f, 670 g&h, and 670 l&m; and the electrically conductive, electrically parallel trace portions: 670 a, 670 b, 670 c, 670 d, 670 e, 670 f, 670 g, 670 h, 670 l and 670 m, are referred to as 670 a-m. The plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h, 670 i and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m is configured both to collect current from the terminatingsolar cell 660 and to interconnect electrically to the terminatingbusbar 680. The plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h, 670 i and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m is configured such that solar-cell efficiency is substantially undiminished in an event that any one electrically conductive, electrically parallel trace portion, for example, 670 h, of the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h, 670 i and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m is conductively impaired. - With further reference to
FIGS. 6A and 6B , in accordance with embodiments of the present invention, the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h, 670 i and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m further includes a first electrically conductive, electricallyparallel trace portion 670 a of a first integrated pair 670 a&b of the electrically conductive, electrically parallel trace portions 670 a-m configured both to collect current from the terminatingsolar cell 660 and to interconnect electrically to the terminatingbusbar 680, and a second electrically conductive, electricallyparallel trace portion 670 b of the first integrated pair 670 a&b of the electrically conductive, electrically parallel trace portions 670 a-m configured both to collect current from the terminatingsolar cell 660 and to interconnect electrically to the terminatingbusbar 680. The first electrically conductive, electricallyparallel trace portion 670 a includes a first end 670 p distal from the terminatingbusbar 680 located parallel to aside 662 of the terminatingsolar cell 660. The second electrically conductive, electricallyparallel trace portion 670 b includes a second end 670 q distal from the terminatingbusbar 680. The second electrically conductive, electricallyparallel trace portion 670 b is disposed proximately to the first electrically conductive, electricallyparallel trace portion 670 a and electrically connected to the first electrically conductive, electricallyparallel trace portion 670 a such that the first distal end 670 p is electrically connected to the second distal end 670 q, for example, at first junction 670 r, or by a linking portion, such that the second electrically conductive, electricallyparallel trace portion 670 b is configured electrically in parallel to the first electrically conductive, electricallyparallel trace portion 670 a when configured to interconnect to the terminatingbusbar 680. In addition, in accordance with embodiments of the present invention, the terminatingbusbar 680 may be disposed above and connected electrically to extended portions, for example, 670 x and 670 y, of the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h, 670 i and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m configured such that the terminatingbusbar 680 is configured to reduce shadowing of the terminatingsolar cell 660. - With further reference to
FIG. 6A , in accordance with embodiments of the present invention, an open-circuit defect 640 is shown such that eighth electrically conductive, electricallyparallel trace portion 670 h is conductively impaired.FIG. 6A illustrates the manner in which the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m is configured such that solar-cell efficiency is substantially undiminished in an event that any one electrically conductive, electrically parallel trace portion, for example, eighth electrically conductive, electricallyparallel trace portion 670 h, of the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m is conductively impaired. Thearrow 648 indicates the nominal electron-flow through a sixth electrically conductive, electricallyparallel trace portion 670 f of the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m essentially unaffected by open-circuit defect 640. In the absence of open-circuit defect 640, an electron-flow indicated byarrow 648 would normally flow through any one electrically conductive, electrically parallel trace portion of the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m, in particular, eighth electrically conductive, electricallyparallel trace portion 670 h. However, when the open-circuit defect 640 is present, this electron-flow divides into two portions shown byarrows 642 and 644:arrow 642 corresponding to that portion of the normal electron-flow flowing to the right along the eighth electrically conductive, electricallyparallel trace portion 670 h to the terminatingbusbar 680, andarrow 644 corresponding to that portion of the normal electron-flow flowing to the left along the eighth electrically conductive, electricallyparallel trace portion 670 h to the seventh electrically conductive, electricallyparallel trace portion 670 g and then to the right along the seventh electrically conductive, electricallyparallel trace portion 670 g to the terminatingbusbar 680. Thus, the net electron-flow represented byarrow 646 flowing to the right along the seventh electrically conductive, electricallyparallel trace portion 670 g is consequently larger than what would normally flow to the right along the seventh electrically conductive, electricallyparallel trace portion 670 g to the terminatingbusbar 680 in the absence of the open-circuit defect 640. It should be noted that open-circuit defect 640 is for illustration purposes only and that embodiments of the present invention compensate for other types of defects in an electrically conductive, electrically parallel trace portion, in general, such as, without limitation to: a delamination of an electrically conductive, electrically parallel trace portion from the terminatingsolar cell 660, corrosion of an electrically conductive, electrically parallel trace portion, and even complete loss of an electrically conductive, electrically parallel trace portion. In accordance with embodiments of the present invention, in the event a defect completely conductively impairs an electrically conductive, electrically parallel trace portion, the physical spacing between adjacent electrically conductive, electrically parallel trace portions, identified with double-headedarrow 649, may be chosen such that solar-cell efficiency is substantially undiminished. Nevertheless, embodiments of the present invention embrace, without limitation thereto, other physical spacings between adjacent electrically conductive, electrically parallel trace portions in the event defects are less severe than those causing a complete loss of one of the electrically conductive, electrically parallel trace portions. - With reference now to
FIG. 6B and further reference toFIG. 6A , in accordance with embodiments of the present invention, a cross-sectional,elevation view 600B of the integrated busbar-solar-cell-current collector 690 ofFIG. 6A is shown.FIG. 6B shows the physical interconnection of the terminatingsolar cell 660 with the terminatingbusbar 680 in the integrated busbar-solar-cell-current collector 690. In accordance with embodiments of the present invention, the interconnection approach employing a carrier film is also conducive to coupling the integrated busbar-solar-cell-current collector 690 directly to the terminatingbusbar 680 without requiring solder. Thus, the integrated busbar-solar-cell-current collector 690 further includes atop carrier film 650. Thetop carrier film 650 includes a first substantially transparent, electrically insulating layer (not shown, but like 550 a ofFIG. 5B ) coupled to the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h, 670 i and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m, for example, electrically conductive, electricallyparallel trace portion 670 a, and disposed above a top portion of the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h, 670 i and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m. - With further reference to
FIGS. 6A and 6B , in accordance with embodiments of the present invention, thetop carrier film 650 further includes a first adhesive medium (not shown, but like 550 b ofFIGS. 5B and 5E ) coupling the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h, 670 i and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m to the electrically insulating layer (like 550 a ofFIG. 5B ). The first adhesive medium (like 550 b ofFIGS. 5B and 5E ) allows for coupling the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h, 670 i and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m to the terminatingsolar cell 660 without requiring solder. The terminatingsolar cell 660 may include anabsorber layer 660 a, aTCO layer 660 b, and ametallic substrate 660 c; a backing layer (not shown) may also be disposed between theabsorber layer 660 a and themetallic substrate 660 c. The plurality of integrated pairs of electrically conductive, electrically parallel trace portions 670 a-m may be connected electrically in series to form a single continuous electrically conductive line (not shown). The single continuous electrically conductive line may be disposed in a serpentine pattern (not shown, but like the pattern oftrace 520 inFIG. 5A ) such that the integrated busbar-solar-cell-current collector 690 is configured to collect current from the terminatingsolar cell 660 and to interconnect electrically to the terminatingbusbar 680. The plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h, 670 i and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m may further include a plurality of electrically conductive lines (not shown, but liketrace 520 ofFIGS. 5B and 5E ), any electrically conductive line of the plurality of electrically conductive lines selected from a group consisting of a copper conductive core clad with a silver cladding, a copper conductive core clad with a nickel coating further clad with a silver cladding and an aluminum conductive core clad with a silver cladding. - With further reference to
FIGS. 6A and 6B , in accordance with embodiments of the present invention, integrated busbar-solar-cell-current collector 690 may include a supplementary isolation strip (not shown) at anedge 664 of the terminatingsolar cell 660 and running along the length of theside 662 to provide additional protection at theedge 664 andside 662 of the terminatingsolar cell 660 from the extended portions, for example, 670 x and 670 y, of the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h, 670 i and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m. In another embodiment of the present invention, the extended portions, for example, 670 x and 670 y, may be configured (not shown) to provide stress relief and to allow folding the terminatingbusbar 680 alongedge 664 under aback side 668 and at theside 662 of terminatingsolar cell 660, so that there is less wasted space and open area between the terminatingsolar cell 660 of one module and the initial solar cell (not shown) of an adjacent module. Moreover, integrated busbar-solar-cell-current collector 690 may include a supplementary carrier-film strip (not shown) at theedge 664 of the terminatingsolar cell 660 and running along the length of theside 662 disposed above and coupled totop carrier film 650 and the terminatingbusbar 680 to affix the terminatingbusbar 680 to the extended portions, for example, 670 x and 670 y. Alternatively, the integrated busbar-solar-cell-current collector 690 may include thetop carrier film 650 extending over the top of the terminatingbusbar 680 and extended portions, for example, 670 x and 670 y, to affix the terminatingbusbar 680 to these extended portions. Thus, these latter two embodiments of the present invention provide a laminate including the terminatingbusbar 680 disposed betweentop carrier film 650, or alternatively the supplementary carrier-film strip, and the supplementary isolation strip (not shown) along theedge 664 andside 662 of the terminatingsolar cell 660. Moreover, thetop carrier film 650, or the supplementary carrier-film strip, is conducive to connecting the terminatingbusbar 680 without requiring solder to the plurality, itself, or to the extended portions, for example, 670 x and 670 y, of the plurality of integrated pairs 670 a&b, 670 c&c, 670 e&f, 670 g&h, 670 i and 670 l&m of electrically conductive, electrically parallel trace portions 670 a-m - With reference now to
FIG. 7A , in accordance with embodiments of the present invention, a combined cross-sectional elevation and perspective view of a roll-to-roll, interconnect-assembly fabricator 700A is shown.FIG. 7A shows the roll-to-roll, interconnect-assembly fabricator 700A operationally configured to fabricate aninterconnect assembly 720. Atop carrier film 716 including an electrically insulating layer, for example a first substantially transparent, electrically insulating layer, is provided to roll-to-roll, interconnect-assembly fabricator 700A in roll form from a first roll ofmaterial 714. The roll-to-roll, interconnect-assembly fabricator 700A includes anfirst unwinding spool 710 upon which the first roll ofmaterial 714 of thetop carrier film 716 including the electrically insulating layer is mounted. As shown, a portion of the first roll ofmaterial 714 is unrolled. The unrolled portion of thetop carrier film 716 including the electrically insulating layer passes to the right and is taken up on a take-upspool 718 upon which it is rewound as athird roll 722 ofinterconnect assembly 720, after conductive-trace material 750 is provided from adispenser 754 and is laid down onto the unrolled portion of thetop carrier film 716 including the electrically insulating layer. Thedispenser 754 of conductive-trace material 750 may be a spool of wire, or some other container providing conductive-trace material. The conductive-trace material 750 may be laid down onto the unrolled portion of thetop carrier film 716 including the electrically insulating layer in an oscillatory motion, but without limitation to a strictly oscillatory motion, indicated by double-headedarrow 758, to create a first plurality of electrically conductive portions configured both to collect current from a first solar cell and to interconnect electrically to a second solar cell such that solar-cell efficiency is substantially undiminished in an event that any one of the first plurality of electrically conductive portions is conductively impaired. As shown inFIG. 7A , a portion of the electrically conductive portions overhang one side of thetop carrier film 716 to allow the electrically conductive portions of the trace to interconnect electrically to the second solar cell on the exposed top side of the trace, while the exposed bottom side of the trace, here shown as facing upward on thetop carrier film 716, allows the electrically conductive portions of the trace in contact with thetop carrier film 716 to interconnect electrically to the first solar cell. Moreover, the conductive-trace material 750 may be disposed in a serpentine pattern to create the plurality of electrically conductive portions configured both to collect current from the first solar cell and to interconnect electrically to the second solar cell. The arrows adjacent to thefirst unwinding spool 710, and the take-upspool 718 indicate that these are rotating components of the roll-to-roll, interconnect-assembly fabricator 700A; thefirst unwinding spool 710, and the take-upspool 718 are shown rotating in clockwise direction, as indicated by the arrow-heads on the respective arrows adjacent to these components, to transport the unrolled portion of the first roll ofmaterial 714 from thefirst unwinding spool 710 on the left to the take-upspool 718 on the right. - With reference now to
FIG. 7B , in accordance with embodiments of the present invention, a combined cross-sectional elevation and perspective view of a roll-to-roll, laminated-interconnect-assembly fabricator 700B is shown.FIG. 7A shows the roll-to-roll, laminated-interconnect-assembly fabricator 700B operationally configured to fabricate a laminated-interconnect assembly 740. The roll-to-roll, laminated-interconnect-assembly fabricator 700B first fabricates theinterconnect assembly 720 shown on the left-hand side ofFIG. 7B from the first roll ofmaterial 714 of thetop carrier film 716 including the electrically insulating layer and from conductive-trace material 750 provided fromdispenser 754. Then, the roll-to-roll, laminated-interconnect-assembly fabricator 700B continues fabrication of the laminated-interconnect assembly 740 by applying abottom carrier film 736 from asecond roll 734. Thebottom carrier film 736 includes a carrier film selected from a group consisting of a second electrically insulating layer, a structural plastic layer, and a metallic layer, and is coupled to the conductive-trace material 750 and is disposed below a bottom portion of the conductive-trace material 750. If a metallic layer is used for thebottom carrier film 736, a supplementary isolation strip (not shown) of a third electrically insulating layer is added to the laminated-interconnect assembly 740 configured to allow interposition of the third electrically insulating layer between thebottom carrier film 736 and a top surface of the first solar cell to provide additional protection at an edge of the first solar cell and to prevent shorting out the solar cell in the event that thebottom carrier film 736 including the metallic layer should ride down the side of the first solar cell. The laminated-interconnect assembly 740 passes to the right-hand side ofFIG. 7B and is taken up on the take-upspool 718 upon which it is wound as afourth roll 742 of laminated-interconnect assembly 740. The arrows adjacent to thefirst unwinding spool 710, asecond unwinding spool 730 and the take-upspool 718 indicate that these are rotating components of the roll-to-roll, laminated-interconnect-assembly fabricator 700B; thefirst unwinding spool 710, and the take-upspool 718 are shown rotating in clockwise direction, as indicated by the arrow-heads on the respective arrows adjacent to these components, to transport the unrolled portion of the first roll ofmaterial 714 from thefirst unwinding spool 710 on the left to the take-upspool 718 on the right. Thesecond unwinding spool 730, and thedispenser 754 are shown rotating in a counterclockwise direction and a clockwise direction, respectively, as indicated by the arrow-heads on the respective arrows adjacent to these components, as they release thebottom carrier layer 736 and the conductive-trace material 750, respectively, in fabrication of the laminated-interconnect assembly 740. The double-headedarrow 758 indicates the motion imparted to the conductive trace material by the roll-to-roll, laminated-interconnect-assembly fabricator 700B creates a first plurality of electrically conductive portions configured both to collect current from a first solar cell and to interconnect electrically to a second solar cell such that solar-cell efficiency is substantially undiminished in an event that any one of the first plurality of electrically conductive portions is conductively impaired. - With reference now to
FIG. 8 , a flow chart illustrates an embodiment of the present invention for a method for roll-to-roll fabrication of an interconnect assembly. At 810, a first carrier film including a first substantially transparent, electrically insulating layer is provided in roll form. At 820, a trace is provided from a dispenser of conductive-trace material. The dispenser may be a spool of wire or other container of conductive-trace material. At 830, a portion of the first carrier film including the first substantially transparent, electrically insulating layer is unrolled. At 840, the trace from the dispenser of conductive-trace material is laid down onto the portion of the first carrier film including the first substantially transparent, electrically insulating layer. At 850, the trace is configured as a first plurality of electrically conductive portions such that solar-cell efficiency is substantially undiminished in an event that any one of the first plurality of electrically conductive portions is conductively impaired. At 860, the portion of the first said first carrier film including the substantially transparent, electrically insulating layer is coupled to a top portion of the trace to provide an interconnect assembly. - In an embodiment of the present invention, configuring the trace also includes: configuring the trace as a second plurality of paired trace portions; configuring a first portion of a paired portion of the second plurality of paired trace portions to allow both collecting current from a first solar cell and electrically interconnecting the first solar cell with a second solar cell; disposing proximately to the first portion, a second portion of the paired portion; and configuring the second portion to allow both collecting current from the first solar cell and electrically interconnecting the first solar cell with the second solar cell. Alternatively, configuring the trace may include disposing the trace in a serpentine pattern that allows for collecting current from the first solar cell and electrically interconnecting to the second solar cell. In an embodiment of the present invention, the method may also include: providing a second carrier film including a second electrically insulating layer; coupling the second carrier film including the second electrically insulating layer to a bottom portion of the trace; and configuring the second electrically insulating layer to allow forming an edge-protecting portion at an edge of the first solar cell. Moreover, the method may include configuring the first substantially transparent, electrically insulating layer to allow forming a short-circuit-preventing portion at an edge of the second solar cell.
- With reference now to
FIG. 9 , a flow chart illustrates an embodiment of the present invention for a method of interconnecting two solar cells. At 910, a first solar cell and at least a second solar cell are provided. At 920, a combined applicable carrier film, interconnect assembly including a trace including a plurality of electrically conductive portions is provided. At 930, the plurality of electrically conductive portions of the trace is configured both to collect current from the first solar cell and to interconnect electrically with the second solar cell such that solar-cell efficiency is substantially undiminished in an event that any one of the plurality of electrically conductive portions is conductively impaired. At 940, the combined applicable carrier film, interconnect assembly is applied and coupled to a light-facing side of the first solar cell. At 950, the combined applicable carrier film, interconnect assembly is applied and coupled to a back side of the second solar cell. - In an embodiment of the present invention, the method also includes applying and coupling the combined applicable carrier film, interconnect assembly to the light-facing side of the first solar cell without requiring solder. In addition, the method may include applying and coupling the combined applicable carrier film, interconnect assembly to the back side of the second solar cell without requiring solder. Moreover, the method includes applying and coupling the combined applicable carrier film, interconnect assembly to the light-facing side of the first solar cell such that a second electrically insulating layer of the applicable carrier film, interconnect assembly forms an edge-protecting portion at an edge of the first solar cell. The method also includes applying and coupling the combined applicable carrier film, interconnect assembly to the back side of the second solar cell such that a first substantially transparent, electrically insulating layer of the applicable carrier film, interconnect assembly forms a short-circuit-preventing portion at an edge of the second solar cell. The method may also include configuring the trace in a serpentine pattern that allows for collecting current from the first solar cell and electrically interconnecting to the second solar cell.
- In accordance with other embodiments of the present invention, the trace does not need to be used in conjunction with the afore-mentioned serpentine interconnect assembly approach, but could be used for other current collection and/or interconnection approaches used in solar cell technology. A trace including a conductive core with an overlying layer of nickel provides the unexpected result that when placed in contact with the TCO layer of a solar cell it suppresses current in the vicinity of short-circuit defects in the solar cell that might occur in the vicinity of the contact of the nickel layer of the trace with the TCO layer. The nickel increases local contact resistance which improves the ability of the solar cell to survive in the event of the formation of a defect, such as a shunt or a near shunt, located in the adjacent vicinity of the contact of the nickel layer of the trace with the TCO layer. If there is such a defect in the vicinity of the contact of the nickel layer of the trace with the TCO layer, the nickel reduces the tendency of the solar cell to pass increased current through the site of the defect, such as a shunt or a near shunt. Thus, the nickel acts as a localized resistor preventing run-away currents and high current densities in the small localized area associated with the site of the defect, such as a shunt or a near shunt. The current-limiting ability of nickel is in contrast, for example, to a low resistivity material such as silver, where the current density becomes so high at the location of the defect due to the high conductivity of silver that nearly almost all the current of the cell would be passed at the location of the defect causing a hot spot that would result in the melting of the silver with the formation of a hole in the solar cell filling with the silver migrating to the site of the defect to form a super-shunt. In contrast, nickel does not readily migrate nor melt in the presence of elevated localized temperatures associated with the site of increased currents attending formation of the defect, such as a shunt or a near shunt. Moreover, in contrast to silver, copper and tin, which tend to electromigrate, migrate or diffuse at elevated temperatures, nickel tends to stay put so that if the site of a shunt occurs in the vicinity of a nickel coated or nickel trace, the nickel has less tendency to move to the location of the shunt thereby further exacerbating the drop of resistance at the shunt site. In addition, experimental results of the present invention indicate that a nickel trace, or a trace including a nickel layer, may actually increase its resistance due the possible formation of a nickel oxide such that the nickel trace, or the trace including the nickel layer, acts like a localized fuse limiting the current flow in the vicinity of the shunt site. In some cases, the efficiency of the solar cell has actually been observed to increase after formation of the shunt defect when the nickel trace, or the trace including the nickel layer, is used in contact with the TCO layer.
- With further reference to
FIGS. 5B and 5E , in accordance with other embodiments of the present invention, thetrace 520 for collecting current from a solar cell, for example, firstsolar cell 510, includes an electrically conductive line including theconductive core 520A, and theoverlying layer 520B that limits current flow to a proximate shunt defect (not shown) in the solar cell, for example, firstsolar cell 510. The proximate shunt defect may be proximately located in the vicinity of an electrical contact between theoverlying layer 520B of the electrically conductive line and theTCO layer 510 b of the solar cell, for example, firstsolar cell 510. Theoverlying layer 520B of the electrically conductive line of thetrace 520 may further include anoverlying layer 520B composed of nickel. Theconductive core 520A of the electrically conductive line of thetrace 520 may further include nickel. Theconductive core 520A may also include a material selected from a group consisting of copper, silver, aluminum, and elemental constituents and alloys having high electrical conductivity, which may be greater than the electrical conductivity of nickel. TheTCO layer 510 b of the solar cell, for example, firstsolar cell 510, may include a conductive oxide selected from a group consisting of zinc oxide, aluminum zinc oxide and indium tin oxide. In addition, theabsorber layer 510 a, for example, absorber layer 112 ofFIG. 1A , of the solar cell, for example, firstsolar cell 510, may include copper indium gallium diselenide (CIGS). Alternatively, in embodiments of the present invention, it should be noted that semiconductors, such as silicon, cadmium telluride, and chalcopyrite semiconductors, as well as other semiconductors, may be used as theabsorber layer 510 a. Moreover, an n-type layer, for example, n-type portion 112 b of absorber layer 112 ofFIG. 1A , of the solar cell, for example, firstsolar cell 510, may be disposed on and electrically coupled to a p-type absorber layer, for example, absorber layer 112 ofFIG. 1A , of the solar cell, for example, firstsolar cell 510, and the n-type layer, for example, n-type portion 112 b of absorber layer 112 ofFIG. 1A , may be selected from a group consisting of a metal oxide, a metal sulfide and a metal selenide. - The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications and variations are possible in light of the above teaching. The embodiments described herein were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.
Claims (21)
1. (canceled)
2. The combined solar-cell, interconnect assembly of claim 11 , wherein said plurality of electrically conductive portions further comprises:
a first portion of said plurality of electrically conductive portions configured both to collect current from said first solar cell and to interconnect electrically to said second solar cell, said first portion comprising a first end distal from said second solar cell; and
a second portion of said plurality of electrically conductive portions configured both to collect current from said first solar cell and to interconnect electrically to said second solar cell, said second portion comprising a second end distal from said second solar cell;
wherein said second portion is disposed proximately to said first portion and electrically connected to said first portion such that said first distal end is electrically connected to said second distal end such that said second portion is configured electrically in parallel to said first portion when configured to interconnect to said second solar cell.
3. The combined solar-cell, interconnect assembly of claim 2 , wherein said plurality of electrically conductive portions further comprises:
said second portion comprising a third end distal from said first solar cell; and
a third portion of said plurality of electrically conductive portions configured both to collect current from said first solar cell and to interconnect electrically to said second solar cell, said third portion comprising a fourth end distal from said first solar cell;
wherein said third portion is disposed proximately to said second portion and electrically connected to said second portion such that said third distal end is electrically connected to said fourth distal end such that said third portion is configured electrically in parallel to said second portion when configured to interconnect with said first solar cell.
4. The combined solar-cell, interconnect assembly of claim 11 , wherein the absorber layer of said first solar cell comprises copper indium gallium diselenide (CIGS).
5-7. (canceled)
8. The combined solar-cell, interconnect assembly of claim 12 , wherein said bottom carrier film further comprises a second adhesive medium coupling said trace to said second electrically insulating layer, and wherein said second adhesive medium allows for coupling said trace to said second solar cell without requiring solder.
9-10. (canceled)
11. A combined solar-cell, interconnect assembly comprising:
a first solar cell, the first solar cell having transparent conductive oxide front electrode layer above a light-facing side of an absorber layer of said first solar cell;
a second solar cell adjacent to the first solar cell separated by a gap; and
an interconnect assembly disposed above the light-facing side of the absorber layer of said first solar cell, the interconnect assembly comprising:
a trace disposed directly upon the transparent conductive oxide front electrode layer above the light-facing side of said first solar cell, wherein said trace is a single, physically continuous electrically conductive line disposed in a serpentine pattern, said trace further comprising:
a plurality of electrically conductive portions, all electrically conductive portions of said plurality of electrically conductive portions configured to collect current from said first solar cell and to interconnect electrically to a said second solar cell;
wherein said plurality of electrically conductive portions is configured such that solar-cell efficiency is substantially undiminished in an event that any one of said plurality of electrically conductive portions is conductively impaired;
a top carrier film, wherein said top carrier film comprises a first substantially transparent, electrically insulating layer coupled to said trace and disposed above a top portion of said trace, said top carrier film further comprising a substantially transparent adhesive medium coupling said top carrier film to said trace such that the adhesive medium is directly physically contacting the trace, said adhesive medium also coupling said top carrier film to said transparent conductive oxide front electrode layer; and
wherein the top carrier film exists only over the first solar cell, as viewed in a direction substantially perpendicular to the layering direction of the transparent conductive oxide front electrode layer above the light-facing side of the absorber layer of said first solar cell, but the top carrier film is not disposed over a portion of the light-facing side of the first solar cell that is closest to the second solar cell;
wherein the gap extends in a direction substantially perpendicular to the layering direction of the transparent conductive oxide front electrode layer above the absorber layer.
12. (canceled)
13. The combined solar-cell, interconnect assembly of claim 11 , wherein the gap is no more than about 2 mm.
14-15. (canceled)
16. The combined solar-cell, interconnect assembly of claim 11 , wherein said trace is a metal wire and said first adhesive couples said trace to said first solar cell without requiring solder by adherence of the trace-bearing top carrier film to the transparent conductive oxide front electrode layer of the first solar cell.
17. A solar-cell module, comprising:
a plurality of interconnected combined solar-cell, interconnect assemblies as claimed in claim 11 .
18-20. (canceled)
21. The solar-cell module of claim 17 , wherein said plurality of electrically conductive portions of each of said plurality of interconnected combined solar-cell, interconnect assemblies further comprises:
a first portion of said plurality of electrically conductive portions configured both to collect current from said first solar cell and to interconnect electrically to said second solar cell, said first portion comprising a first end distal from said second solar cell; and
a second portion of said plurality of electrically conductive portions configured both to collect current from said first solar cell and to interconnect electrically to said second solar cell, said second portion comprising a second end distal from said second solar cell;
wherein said second portion is disposed proximately to said first portion and electrically connected to said first portion such that said first distal end is electrically connected to said second distal end such that said second portion is configured electrically in parallel to said first portion when configured to interconnect to said second solar cell.
22. The solar-cell module of claim 21 , wherein said plurality of electrically conductive portions of each of said plurality of interconnected combined solar-cell, interconnect assemblies further comprises:
said second portion comprising a third end distal from said first solar cell; and
a third portion of said plurality of electrically conductive portions configured both to collect current from said first solar cell and to interconnect electrically to said second solar cell, said third portion comprising a fourth end distal from said first solar cell;
wherein said third portion is disposed proximately to said second portion and electrically connected to said second portion such that said third distal end is electrically connected to said fourth distal end such that said third portion is configured electrically in parallel to said second portion when configured to interconnect with said first solar cell.
23. The solar-cell module of claim 17 , wherein each of said plurality of interconnected combined solar-cell, interconnect assemblies further comprises: a bottom carrier film, wherein said bottom carrier film comprises a carrier is film selected from a group consisting of a second electrically insulating layer, a structural plastic layer, and a metallic layer, said bottom carrier film directly coupled to said trace and disposed below a bottom portion of said trace.
24. The solar-cell module of claim 23 , wherein said bottom carrier film further comprises a second adhesive medium coupling said trace to said second electrically insulating layer, and wherein said second adhesive medium allows for coupling said trace to said second solar cell without requiring solder.
25. The solar-cell module of claim 17 , wherein the gap is no more than about 2 mm.
26. The solar-cell module of claim 17 , wherein said trace is a metal wire and said first adhesive couples said trace to said first solar cell without requiring solder by adherence of the trace-bearing top carrier film to the transparent conductive oxide front electrode layer of the first solar cell.
27. The solar-cell module of claim 17 , wherein the absorber layer of said first solar cell comprises copper indium gallium diselenide (CIGS).
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2017
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US10056521B2 (en) | 2008-03-20 | 2018-08-21 | Beijing Apollo Ding Rong Solar Technology Co., Ltd. | Wire network for interconnecting photovoltaic cells |
US10158031B2 (en) | 2008-03-20 | 2018-12-18 | Beijing Apollo Ding Rong Solar Technology Co., Ltd. | Interconnect assembly |
Also Published As
Publication number | Publication date |
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US20100043863A1 (en) | 2010-02-25 |
US9620660B2 (en) | 2017-04-11 |
US20130276855A1 (en) | 2013-10-24 |
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