WO1999062125A1 - Cellule solaire comportant une diode integrale en parallele a croissance monolithique - Google Patents

Cellule solaire comportant une diode integrale en parallele a croissance monolithique Download PDF

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Publication number
WO1999062125A1
WO1999062125A1 PCT/US1999/011171 US9911171W WO9962125A1 WO 1999062125 A1 WO1999062125 A1 WO 1999062125A1 US 9911171 W US9911171 W US 9911171W WO 9962125 A1 WO9962125 A1 WO 9962125A1
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WO
WIPO (PCT)
Prior art keywords
solar cell
contact
cell
diode
bypass diode
Prior art date
Application number
PCT/US1999/011171
Other languages
English (en)
Inventor
Frank Ho
Milton Y. Yeh
Chaw-Long Chu
Peter A. Iles
Original Assignee
Tecstar Power Systems, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tecstar Power Systems, Inc. filed Critical Tecstar Power Systems, Inc.
Priority to EP04005841A priority Critical patent/EP1443566B1/fr
Priority to AT99925702T priority patent/ATE450055T1/de
Priority to JP2000551443A priority patent/JP2002517098A/ja
Priority to AU41938/99A priority patent/AU4193899A/en
Priority to PCT/US1999/011171 priority patent/WO1999062125A1/fr
Priority to DE69941667T priority patent/DE69941667D1/de
Priority to EP99925702A priority patent/EP1008188B1/fr
Publication of WO1999062125A1 publication Critical patent/WO1999062125A1/fr

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    • 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
    • H01L31/06—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 characterised by potential barriers
    • H01L31/068—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 characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
    • H01L31/0687—Multiple junction or tandem solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components 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
    • H01L27/142—Energy conversion devices
    • 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
    • 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
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/184—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof the active layers comprising only AIIIBV compounds, e.g. GaAs, InP
    • H01L31/1852—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof the active layers comprising only AIIIBV compounds, e.g. GaAs, InP comprising a growth substrate not being an AIIIBV compound
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481—Disposition
    • H01L2224/48135—Connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip
    • H01L2224/48137—Connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip the bodies being arranged next to each other, e.g. on a common substrate
    • 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
    • Y02E10/544—Solar cells from Group III-V materials

Definitions

  • the present invention relates to solar cells.
  • the present invention relates to methods and apparatuses for providing a solar cell with an integral diode. Description Of The Related Art
  • Photovoltaic cells are well-known devices which convert solar energy into electrical energy. Solar cells have long been used to generate electrical power in both terrestrial and space applications. Solar cells offer several advantages over more conventional power sources. For example, solar cells offer a clean method for generating electricity. Furthermore, solar cells do not have to be replenished with fossil fuels. Instead, solar cells are powered by the virtually limitless energy of the sun. However, the use of solar cells has been limited because solar cells are a relatively expensive method of generating electricity. Nonetheless, the solar cell is an attractive device for generating energy in space, where low-cost conventional power sources are unavailable.
  • Solar cells are typically assembled into arrays of solar cells connected together in series, or in parallel, or in a series-parallel combination.
  • the desired output voltage and current at least in part, determine the number of cells in an array, as well as the array topology.
  • each cell will be forward biased.
  • the shadowed cell or cells may become reversed biased because of the voltage generated by the unshadowed cells. Reverse biasing of a cell can cause permanent degradation in cell performance or even complete cell failure. To guard against such damage, it is customary to provide protective bypass diodes.
  • One bypass diode may be connected across several cells, or for enhanced reliability, each cell may have its own bypass diode. Multijunction solar cells are particularly susceptible to damage when subjected to a reverse bias condition. Thus, multijunction cells in particular benefit from having one bypass diode per cell.
  • a bypass diode is connected in an anti-parallel configuration, with the anode and the cathode of the bypass diode respectively connected to the cathode and the anode of the solar cell, so that the bypass diode will be reversed biased when the cells are illuminated.
  • the bypass diode connected across the shadowed cell in turn becomes forward biased. Most of the current will flow through the bypass diode rather than through the shadowed cell, thereby allowing current to continue flowing through the array.
  • the bypass diode limits the reverse bias voltage across the shadowed cell, thereby protecting the shadowed cell.
  • each conventional method has its drawbacks. For example, in an attempt to provide increased bypass protection, one method involves locating a bypass diode between adjacent cells, with the anode of the bypass diode connected to one cell and the cathode of the diode connected to an adjoining cell.
  • this technique requires that the cells be assembled into an array before the bypass diode protection can be added. This assembly method is difficult and inefficient.
  • this technique requires the bypass diodes to be added by the array assembler, rather than the cell manufacturer.
  • this technique requires the cells to be spaced far enough apart so as to accommodate the bypass diode. This spacing results in the array having a lower packing factor, and thus, the array is less efficient on an area basis.
  • Another conventional technique providing a bypass diode for each cell requires that a recess be formed on the back of the cell in which a bypass diode is placed.
  • Each cell is provided with a first polarity contact on a front surface of the cell and a second polarity contact is provided on a back surface of each cell.
  • An "S" shaped interconnect must then be welded from a back surface contact of a first cell to a front surface contact of an adjoining cell.
  • this technique disadvantageousl ⁇ requires the cells to be spaced far enough apart to accommodate the interconnect which must pass between the adjoining cells. Additional disadvantages of this method include the possibility of microcracks generated during formation of the recess.
  • this technique requires a thick bondline of adhesive, thereby adding stress-risers, increasing stresses generated during temperature cycling.
  • the present conventional technique requires the connection of the interconnect to the adjoining cell to be performed by the array assembler as opposed to the cell manufacturer.
  • the solar cell is a multijunction cell.
  • the bypass diode is monolithicalfy grown over at least a portion of the solar cell.
  • the solar cell is formed from at least group III, IV, or V materials.
  • the diode includes at least an N-type GaAs layer and a P-type GasAs layer.
  • the diode is formed using lower bandgap materials, such as germanium or InGaAs.
  • the solar cell includes a germanium Ge substrate.
  • the Ge substrate may further include a photoactive junction.
  • the substrate is formed from at least one of the following materials: semiconductors, such as GaAs, Si, or InP, and insulators, such as sapphire.
  • the substrate is a single crystal.
  • a C-clamp conductor interconnects at least one solar cell contact to at least one bypass diode contact.
  • an integrally metallized layer is used to interconnect at least one solar cell contact to at least one bypass diode contact.
  • the integrally metallized layer is deposited over an insulating layer to prevent the integrally metallized layer from shorting to one or more other layers.
  • a cap layer interconnects a first diode polarity with the solar cell.
  • the bypass diode is epitaxially grown on a solar cell having one or more junctions.
  • the solar cell may be formed from at least one or more of the following materials: GaAs, InP, GalnP 2 , and AIGaAs.
  • other lll-V compounds are used to form at least a portion of the solar cell.
  • Figure 1 illustrates a first processing step used to construct one embodiment of the present invention
  • Figure 2 illustrates a second processing step used to construct one embodiment of the present invention
  • Figure 3 illustrates a third processing step used to construct one embodiment of the present invention
  • Figure 4 illustrates a fourth processing step used to construct one embodiment of the present invention
  • Figure 5 illustrates a fifth processing step used to construct one embodiment of the present invention
  • Figure 6 illustrates a sixth processing step used to construct one embodiment of the present invention
  • Figure 7 illustrates a seventh processing step used to construct one embodiment of the present invention
  • Figure 8 illustrates an eighth processing step used to construct one embodiment of the present invention
  • Figure 9 illustrates a ninth processing step used to construct one embodiment of the present invention
  • Figure 10 illustrates a tenth processing step used to construct one embodiment of the present invention
  • Figure 11 illustrates one embodiment of the present invention, including a discrete interconnect
  • Figure 12 illustrates one embodiment of the present invention, including an integral interconnect
  • Figure 13A illustrates a perspective view of one embodiment of the present invention
  • Figure 13B illustrates in greater detail the bypass diode illustrated in Figure 13A.
  • Figure 14A illustrates one embodiment of the present invention with a buried bypass diode
  • Figure 14B illustrates the embodiment of Figure 14A after further processing acts are performed
  • Figure 15A illustrates a first method of interconnecting solar cells;
  • Figure 15B illustrates a second method of interconnecting solar cells.
  • the present invention relates to a solar cell with at least one integral bypass diode.
  • the solar cell may be a single junction or multijunction cell.
  • a bypass diode is epitaxially grown on a multijunction solar cell.
  • the solar cell/bypass diode device may be interconnected with other solar cells to form series and/or parallel strings of solar cells. The strings may be further connected to form a reliable and robust solar cell array.
  • the solar cell array may be mounted to a space vehicle, thereby providing power to the space vehicle.
  • Figure 1 shows a sequence of lll-V layers 106-122 which are grown sequentially on a Ge substrate 102 in one embodiment of the present invention to form a multijunction solar cell 100.
  • the Ge substrate 102 may further include a photoactive junction.
  • the layers are epitaxially grown, meaning that they replicate the single crystalline structure of material.
  • the growth parameters (deposition temperature, growth rate, compound alloy composition, and impurity dopant concentrations) are preferably optimized to provide layers with the desired electrical qualities and thickness, to thereby obtain the required overall cell performance.
  • the epitaxial techniques which may be used to grow the cell layers include, by way of example, MOCVD (metal-organic chemical vapor deposition) epitaxy, sometimes called OMVPE (organic-metallic vapor phase epitaxy), MBE (molecular beam expitaxy), and MOMBE (metal- organic molecular beam epitaxy).
  • MOCVD metal-organic chemical vapor deposition
  • OMVPE organic-metallic vapor phase epitaxy
  • MBE molecular beam expitaxy
  • MOMBE metal- organic molecular beam epitaxy
  • an N doped GaAs base layer 106 is grown over and overlays at least a portion of the substrate 102. At the interface between layer 102 and layer 106 a photoactive junction is formed.
  • the photoactive junction is an N + GaAs/N + Ge heterodiode.
  • a P-type Ge substrate 102 is used, and diffusion of As from the layer 106 forms an N/P junction in the substrate 102.
  • a highly P doped GaAs emitter layer 108 is grown over at least a portion of the GaAs base layer 106.
  • the base layer 106 and the emitter layer 108 together form a lower cell stage.
  • a highly P doped AIGaAs window layer 110 overlays the emitter layer 108.
  • a tunnel diode, including very highly doped P and N layers 112, 114 is grown over the window layer 110.
  • the last two layers grown for the solar cell are respectively a highly P doped AIGaAs window 120, which is a thin, transparent layer that passivates (reduces carrier recombination) the surface of the emitter layer 118 of the top cell (GalnP 2 ), and a GaAs cap-layer 122 onto which the front surface ohmic contacts are deposited, in one embodiment, the contacts are in grid-finger form, to balance low electrical resistance and high optical transparency. However, other contact patterns may be used as well.
  • the integral bypass diode is included in the monolithically-grown cell structure by the growth of several additional layers.
  • the cap layer 122 is selectively removed between the gridlines, and anti-reflective coatings are deposited over the top window layer 120.
  • the three cell, three-junction, solar cell 100, illustrated in Figure 1 is only one of many possible cell embodiments which can be used with the present invention.
  • a complementary structure with the polarities of one or more layers switched (i.e. N doped layers are, instead, P doped, and P doped layers are, instead, N doped), may be used.
  • the cell and diode configurations illustrated in the figures and discussed below can be changed from P/N to N/P.
  • the doping concentrations or layer thicknesses may be varied.
  • the solar cell 100 may include four or more photovoltaic cells, or only one or two cells.
  • the solar cell may alternatively include only one junction or two or more junctions.
  • the cell 100 may include four junctions.
  • the solar cell 100 may include cells made from other materials, such as AIGaAs or InP.
  • the substrate 102 may be formed using a variety of different materials.
  • the solar cell 100 may use other semiconductors, such as GaAs, Si, or InP for the substrate, rather than the Ge substrate 102 illustrated in Figure 1.
  • insulating substrates such as sapphire, may be used.
  • the substrate 102 is a single crystal. If the solar cell 100 is intended for space use, such as on a space vehicle or satellite, then the cell materials are preferably space-qualified for the appropriate space environment.
  • the solar cell 100 and bypass diode may be space qualified to operate in an AMO radiation environment.
  • One method of fabricating the bypass diode will now be described. As illustrated in Figure 2, the bypass diode 212 is included in the solar cell structure using additional five grown layers 202, 204, 206, 208, 210.
  • the layers 106-122 comprising the photovoltaic portions of the multijunction solar cell 100, are first grown, and the growth cycle is continued to grow the additional layers 202-210.
  • the additional layers in order are:
  • the highly doped N-GaAs connecting layer 202 used to reduce contact resistance to the N-GaAs diode layer 206 and to the highly doped GaAs cap layer 122.
  • the stop-etch layer 204 (highly N-doped AIGaAs or GalnP) used to allow controlled etch-removal of the three diode layers 206-210.
  • the N doped GaAs layer 206 comprising the negatively doped part of the bypass diode 212.
  • the P doped GaAs layer 208 comprising the positively doped part of the of the bypass diode 212.
  • the highly doped P-GaAs cap layer 210 used to provide good metallic contact to the P-layer 208 of the diode 212.
  • embodiments of the present invention may utilize a different number of layers, formed from different types of materials, and having different dopants than the embodiment described above.
  • the use of the complementary structure that is, N/P rather than P/N, can similarly consist of N/P multijunction solar cells, and an N/P bypass diode.
  • the diode 212 may be formed using lower bandgap materials, such as germanium or InGaAs.
  • the layer 202 may be omitted, leaving the layer 204 to provide stop-etching and electrical conduction.
  • the photoactive solar cell layers and the diode layers illustrated in Figure 2 are epitaxially grown using conventional MOCVD and/or MBE technologies.
  • the front surface of the grown layer sequence is protected with a photoresist layer 302, which is exposed through a photomask (not shown) patterned to leave the diode layers covered with resist.
  • the diode cap layer 210 and the N and P diode layers 206, 208 are etched down to the stop-etch layer 204. The etching may be performed using citric acid heated to 45°C.
  • the stop etch layer 204 is removed where the photoresist layer 302 does not mask, and appropriate portions of the N doped GaAs connecting layer 202 is exposed.
  • the etchant may be BHF (buffered hydrofloric) acid. If the stop etch layer 204 is GalnP, then in another embodiment, the etchant may be HCL.
  • the photoresist layer 302 is removed using acetone. Microstripping techniques may be used to remove any residual photoresist left remaining after the acetone removal process. Once the photoresist layer 302 is removed, the front contact fabrication process, including corresponding photoresist coating, baking, exposing, developing, metal evaporation, and lift off operations, can take place. Another photoresist layer (not shown) is coated over the whole surface.
  • the photoresist layer is then baked and exposed with a photomask which leaves opened areas where contacts are to be deposited to the front surface gridlines and pads, to a small region of the exposed N doped GaAs layer 202, and to the diode cap layer 210.
  • Metals predominantly including Ag, are evaporated into the exposed areas and over the remaining photoresist layer.
  • the photoresist also provides open slots in the photoresist, to provide gridlines, and bars/pad contacts to the cell.
  • a lift-off process is performed.
  • the solar cell slice 100 is immersed in acetone, causing the photoresist to swell, and thereby breaks the metal film everywhere except on the regions designated to retain contacts, including contacts 702, 704.
  • metals predominantly including Ag, are evaporated over the back surface of the Ge substrate 102 to form a back metal contact 802.
  • the contacts 702, 704, 802 are then heat-treated or sintered.
  • the GaAs cap layer 122 is etched off the major part of the exposed front surface, as illustrated in Figure 9.
  • the cap layer 122 remains under the metallized areas, forming part of a low resistance contact mechanism.
  • the diode pad metal contacts 702, 704, and the small contacts shown around the diode 212 are protected with a resist mask, and on the rest of the surface, an anti-reflecting layer 1002 is deposited.
  • the top, P-side, diode contact 702 is connected to the back cell (N-grid) contact 802 by bonding a thin interconnect 1102.
  • the electrical connection between the P layer 208 of the P/N GaAs diode 212 and the backside of the N doped Ge substrate 102 is formed by a C-clamp 1102, which is bonded to both the front diode contact 702 and the rear Ge contact 802.
  • bypass diode 212 is connected across both of the photovoltaic cells.
  • the bypass diode may be used to bypass one or more photovoltaic cells.
  • one embodiment of the present invention can be used to bypass all the cells in a solar cell structure 100, or less than all the cells in the solar cell structure 100.
  • a variety of other interconnect techniques may be used to connect the solar cell to the bypass diode. The final choice may depend on the additional complexity and the effect on cell yields and costs which results from the use of these alternative approaches. By way of example, descriptions of several other follow.
  • a short contact between the diode top contact and a metallized area on a small trough etched down through the cascade cell layers 1206-1218 to expose the Ge substrate 1204 may be used, rather than a C-clamp.
  • the trough may remove less than 1 % of the active cell area, and may be located close to the top contact of the bypass diode.
  • the embodiment illustrated in Figure 12 includes a front metal contact 1224, a rear metal contact 1202, and an anti-reflective coasting 1226. Several different contact configurations may be used.
  • a short discrete metal interconnect is bonded to the diode contact at one end, and is bonded directly to the Ge surface exposed in the trough.
  • the interconnect is gold-plated.
  • a variety of techniques may be used to make the bond.
  • the bond is made using eutectic Au-Ge soldering.
  • an additional step may be added to the normal cell processing. The front surface is masked at substantially all regions except where the Ge contact area is needed using dry film or liquid photoresist.
  • the edges of the trough may be protected with resist by using an opened area just inside the etched area.
  • the metal for contacting the N- Ge may be deposited in the same or a similar deposition sequence as when the front contacts to the cascade cell 100 and the diode contacts 702, 704 are formed. In the present case, TiAuAg or equivalent contacts may serve for the exposed areas on the front surface.
  • a short discrete metal interconnect is bonded to the diode P-contact and the contact to the N-Ge.
  • a trough or recess is etched to the Ge interface 1204 through the diode and cell layers 1206-1218.
  • the wall or walls of the trough are formed by the cell layers.
  • a mask is then used to expose the edges of the trough, and an insulating layer 1220 is deposited on the layer edges and on the area between the diode cap layer 1218 and the trough.
  • Another mask which can be included in the main front contact mask, is used to deposit metal 1222, which connects the front contact of the diode to the trough exposing the Ge substrate 1204.
  • no diode contacts are necessary for the substrate-to-diode interconnect 1222.
  • Figure 13A illustrates a perspective view of one embodiment of the solar cell 100, including the bypass diode circuit 212.
  • the front surface of the solar cell 100 includes grid lines 1302 interconnected by an ohmic bar 1306.
  • the bar 1306 is shaped to provide an area or recess where the diode 212 is formed, in one embodiment, the diode 212 is interconnected to the back contact 802 of the solar cell 100 using the C-clamp connector 1102 illustrated in Figure 11.
  • Figure 13B illustrates in greater detail the bypass diode 212 illustrated in Figure 13A.
  • the sides of the diode 212 are interdigitated with the ohmic bar 1306. Thus, the distance between the diode 212 and the bar 1306 is reduced, and more of the bar 1306 is in proximity with the diode 212.
  • three tabs 1304 are mounted on the solar cell 100 for interconnection to an adjoining assembly.
  • the tabs 1304 may include a U-shaped stress relief section, also called a Z- tab.
  • a first side of each of the tabs 1304 is connected to an anode of the cell 100.
  • the solar cell 100 may be interconnected to a second solar cell by connecting a second side of the tabs 1304 to a cathode of the second solar cell.
  • the tabs are formed from silver, silver-Invar, or silver-clad moly materials.
  • a coverglass may be used to protect the solar cell/bypass diode device.
  • the coverglass may be composed of ceria-doped borosilicate coverglass.
  • the coverglass may have a thickness around 50 ⁇ m to 200 ⁇ m.
  • the ceria-doped coverglass provides radiation resistant shielding for charged and uncharged particles.
  • the coverglass will remain substantially transparent when exposed to an AMO space radiation environment spectrum (the spectrum found at Earth's orbit around the sun, outside of Earth's atmosphere).
  • a major advantage of one embodiment of the integral bypass diode is that the diode does not extend above the front surface of the solar cell 100, and therefore does not require the use of a notched or slotted coverglass to accommodate the integral diode.
  • the integral diode may extend above the front or top surface of the solar cell 100.
  • coverglass materials and dimensions can be used as well.
  • FIG 14A illustrates still another embodiment of the present invention.
  • the illustrated solar cell 1400 includes a novel buried protective bypass diode 1410.
  • the protective bypass diode 1410 is used to protect the solar cell from reverse bias conditions which can result from the shadowing of the cell.
  • the exemplary grown layer sequence illustrated in Figure 14A is similar to that of Figure 1A.
  • Two additional buried layers 1406, 1408 are provided for polarity matching with the Ge+ emitter 1404.
  • the solar cell 1400 includes a Ge substrate 1402 over which the Ge emitter layer 1404 is grown.
  • Isolated diode layers 1412-1420 form a portion of the bypass diode function.
  • Layers 1422, 1424 form the conventional top cell, over which is a window layer 1426, and a cap layer 1428.
  • a complementary structure with the polarities of one or more layers switched from those illustrated in Figure 14A (i.e. P doped layers are, instead, N doped, and N doped layers are, instead, P doped), may be used.
  • the solar cell is processed, and, as illustrated in Figure 14B, a back metal contact 1430 and a front metal diode contact 1440 are formed. In addition, an anti-reflective coating 1432 is applied.
  • a short integral connector 1436 is formed over an insulator 1434 from the cap layer
  • bypass diode 1410 is connected in an anti-parallel configuration with respect to the photovoltaic portions of the solar cell 1400 and thereby is configured to provide reverse bias protection to the photovoltaic portions of the solar cell 1400.
  • a solar cell incorporating an integral diode onto cascaded cells has achieved efficiencies of well over 21 %, and even over 23.5%. These efficiencies are comparable to conventional cascade cells lacking the integral bypass diode.
  • the integral bypass diode has a forward bias voltage drop of approximately 1.4 to 1.8 volts when conducting 400 mA of forward current.
  • the reverse breakdown voltage is sufficient to block current passing into the bypass diode when the solar cell is forward biased during normal, unshadowed, illumination, in one embodiment, the reverse breakdown voltage is greater than 2.5V.
  • samples of one embodiment of the present invention, with cell areas of approximately 24 cm 2 have sustained repeated 10-second pulses of 400 mA of reverse current with no significant change in performance.
  • the following performance changes were observed: Parameter Pre-test Measurement Post-test Measurement
  • VOC OPEN CIRCUIT VOLTAGE
  • the solar cell design described above is modified to even further facilitate its use in either space-based or terrestrial-based concentrator systems.
  • non-concentrator systems there is a need to protect against shadowing of the solar cells from clouds, birds, buildings, antennas, or other structures.
  • protective diodes are still used to protect solar cells from reverse bias conditions resulting from shadowing.
  • solar cells in concentrator assemblies typically generate much more power than non-concentrator solar cells.
  • the protective diodes need to be capable of dissipating heat associated with the much greater power that is bypassed.
  • distributing multiple separated bypass integral diodes across at least a portion of the surface of the solar cell helps distribute the heat dissipation.
  • each of the multiple integral diodes bypasses a portion of the reverse bias power, and correspondingly dissipates a portion of the associated heat.
  • a single integral diode does not have to bypass all the reverse bias power or dissipate all the heat associated with such bypass function.
  • the multiple integral bypass diodes may be formed using the same technique described above with regard to forming one integral diode. In one embodiment, different photomasks are used to form the diodes and diode contacts.
  • FIG. 15A illustrates one method of interconnecting in series solar cells having integral bypass diodes.
  • two solar cells 1502, 1510, with corresponding integral bypass diodes 1504, 1514 are interconnected to form a solar cell string 1500.
  • a first interconnect 1508 is connected to a front contact 1506, overlaying cascaded cells of the solar cell 1502, and to a front contact 1512, overlaying the integral bypass diode
  • the first interconnect 1508 may be a jumper bar, wire, or the like.
  • a second interconnect 1518 is connected to the front contact 1506 of the solar cell 1502, and to a back contact 1516 of the solar cell 1510.
  • the second interconnect 1518 may be a z-tab, wire, or the like.
  • the bypass diodes 1504, 1514 are conveniently located on the edge or side opposite the Ohmic cell contact pads 1506, 1520.
  • Figure 15B illustrates another method of interconnecting in series solar cells having integral bypass diodes.
  • the first interconnect 1508 is connected to the front contact 1506 of the solar cell 1502, and to the front contact 1512 of the solar cell 1510.
  • the second interconnect 1518 is connected to the front contact 1512 and to the back contact 1516 of the solar cell 1510.
  • the second interconnect 1518 may be a C-clamp, wire, or the like.
  • This embodiment can advantageously use only one interconnect between two adjacent cells, and the series connection between the cells can be made on the front surfaces of the cells.
  • the cells can first have their corresponding C-ciamps individually affixed by the cell manufacturer.
  • the solar cell panel assembler can then appropriately position the cells in long strings, and then interconnect the front contacts of the cells as illustrated in Figure 15B. This procedure can provide for the efficient, high yield manufacture of solar cells, solar cell strings, and solar cell panels.

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Abstract

L'invention concerne des systèmes et des procédés de protection d'une cellule solaire. Cette dernière comporte une première partie de cellule solaire, laquelle comporte au moins une jonction et au moins un contact de cellule solaire sur sa face arrière. Au moins une partie de diode en parallèle est obtenue par croissance épitaxiale sur la première partie de cellule solaire. La diode en parallèle comporte au moins un contact. Une interconnexion connecte le contact de la cellule solaire avec le contact de la diode.
PCT/US1999/011171 1998-05-28 1999-05-19 Cellule solaire comportant une diode integrale en parallele a croissance monolithique WO1999062125A1 (fr)

Priority Applications (7)

Application Number Priority Date Filing Date Title
EP04005841A EP1443566B1 (fr) 1998-05-28 1999-05-19 Cellule solaire comportant une diode de protection en parallele integrée monolithiquement
AT99925702T ATE450055T1 (de) 1998-05-28 1999-05-19 Solarzelle mit einer integrierten monolitisch gewachsenen bypassdiode
JP2000551443A JP2002517098A (ja) 1998-05-28 1999-05-19 バイパスダイオードを有する太陽電池
AU41938/99A AU4193899A (en) 1998-05-28 1999-05-19 Solar cell having an integral monolithically grown bypass diode
PCT/US1999/011171 WO1999062125A1 (fr) 1998-05-28 1999-05-19 Cellule solaire comportant une diode integrale en parallele a croissance monolithique
DE69941667T DE69941667D1 (de) 1998-05-28 1999-05-19 Solarzelle mit einer integrierten monolitisch gewachsenen Bypassdiode
EP99925702A EP1008188B1 (fr) 1998-05-28 1999-05-19 Cellule solaire comportant une diode intégrale en parallèle a croissance monolithique

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US60/087,206 1998-05-28
PCT/US1999/011171 WO1999062125A1 (fr) 1998-05-28 1999-05-19 Cellule solaire comportant une diode integrale en parallele a croissance monolithique

Publications (1)

Publication Number Publication Date
WO1999062125A1 true WO1999062125A1 (fr) 1999-12-02

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Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2346010A (en) * 1999-01-25 2000-07-26 Marconi Applied Technologies Solar cell arrangements
EP1056137A1 (fr) * 1999-05-11 2000-11-29 Angewandte Solarenergie - ASE GmbH Cellule solaire avec une diode de protection et son procédé de fabrication
WO2001006565A1 (fr) * 1999-07-14 2001-01-25 Hughes Electronics Corporation Ensemble monolithique diode en parallele et pile solaire
US6600100B2 (en) * 1998-05-28 2003-07-29 Emcore Corporation Solar cell having an integral monolithically grown bypass diode
US6864414B2 (en) * 2001-10-24 2005-03-08 Emcore Corporation Apparatus and method for integral bypass diode in solar cells
FR2863775A1 (fr) * 2003-12-15 2005-06-17 Photowatt Internat Sa Module photovoltaique avec un dispositif electronique dans l'empilage lamine.
US7071407B2 (en) 2002-10-31 2006-07-04 Emcore Corporation Method and apparatus of multiplejunction solar cell structure with high band gap heterojunction middle cell
WO2012053471A1 (fr) 2010-10-22 2012-04-26 シャープ株式会社 Cellule de batterie solaire
US8263855B2 (en) 2001-10-24 2012-09-11 Emcore Solar Power, Inc. Multijunction solar cell with a bypass diode
EP2546889A1 (fr) * 2011-07-12 2013-01-16 Astrium GmbH Cellule solaire et ensemble de cellule solaire
US8513518B2 (en) 2006-08-07 2013-08-20 Emcore Solar Power, Inc. Terrestrial solar power system using III-V semiconductor solar cells
US8536445B2 (en) 2006-06-02 2013-09-17 Emcore Solar Power, Inc. Inverted metamorphic multijunction solar cells
US8686282B2 (en) 2006-08-07 2014-04-01 Emcore Solar Power, Inc. Solar power system for space vehicles or satellites using inverted metamorphic multijunction solar cells
US8890044B2 (en) 2008-10-24 2014-11-18 Suncore Photovoltaics, Incorporated Solar cell system
US8895342B2 (en) 2007-09-24 2014-11-25 Emcore Solar Power, Inc. Heterojunction subcells in inverted metamorphic multijunction solar cells
US8946608B2 (en) 2008-02-01 2015-02-03 Suncore Photovoltaics, Inc. Solar tracking system
US9012771B1 (en) 2009-09-03 2015-04-21 Suncore Photovoltaics, Inc. Solar cell receiver subassembly with a heat shield for use in a concentrating solar system
US9331228B2 (en) 2008-02-11 2016-05-03 Suncore Photovoltaics, Inc. Concentrated photovoltaic system modules using III-V semiconductor solar cells
US9806215B2 (en) 2009-09-03 2017-10-31 Suncore Photovoltaics, Inc. Encapsulated concentrated photovoltaic system subassembly for III-V semiconductor solar cells
US9923112B2 (en) 2008-02-11 2018-03-20 Suncore Photovoltaics, Inc. Concentrated photovoltaic system modules using III-V semiconductor solar cells
US10153388B1 (en) 2013-03-15 2018-12-11 Solaero Technologies Corp. Emissivity coating for space solar cell arrays
US10381505B2 (en) 2007-09-24 2019-08-13 Solaero Technologies Corp. Inverted metamorphic multijunction solar cells including metamorphic layers
CN113169241A (zh) * 2018-11-30 2021-07-23 瑞士电子显微技术研究与开发中心股份有限公司 光伏模组

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US5330583A (en) * 1991-09-30 1994-07-19 Sharp Kabushiki Kaisha Solar battery module
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US5616185A (en) * 1995-10-10 1997-04-01 Hughes Aircraft Company Solar cell with integrated bypass diode and method

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US4759803A (en) * 1987-08-07 1988-07-26 Applied Solar Energy Corporation Monolithic solar cell and bypass diode system
US5330583A (en) * 1991-09-30 1994-07-19 Sharp Kabushiki Kaisha Solar battery module
WO1996018213A1 (fr) * 1994-12-08 1996-06-13 Pacific Solar Pty. Limited Cellules solaires multicouches protegees par des diodes en parallele
US5616185A (en) * 1995-10-10 1997-04-01 Hughes Aircraft Company Solar cell with integrated bypass diode and method

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See also references of EP1008188A4 *

Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6600100B2 (en) * 1998-05-28 2003-07-29 Emcore Corporation Solar cell having an integral monolithically grown bypass diode
GB2346010A (en) * 1999-01-25 2000-07-26 Marconi Applied Technologies Solar cell arrangements
EP1056137A1 (fr) * 1999-05-11 2000-11-29 Angewandte Solarenergie - ASE GmbH Cellule solaire avec une diode de protection et son procédé de fabrication
US6316716B1 (en) * 1999-05-11 2001-11-13 Angewandte Solarenergie - Ase Gmbh Solar cell and method for producing such a cell
WO2001006565A1 (fr) * 1999-07-14 2001-01-25 Hughes Electronics Corporation Ensemble monolithique diode en parallele et pile solaire
US6635507B1 (en) 1999-07-14 2003-10-21 Hughes Electronics Corporation Monolithic bypass-diode and solar-cell string assembly
US7759572B2 (en) * 2001-10-24 2010-07-20 Emcore Solar Power, Inc. Multijunction solar cell with a bypass diode having an intrinsic layer
US7592538B2 (en) * 2001-10-24 2009-09-22 Emcore Solar Power, Inc. Method of fabricating a multijunction solar cell with a bypass diode having an intrinsic layer
US8263855B2 (en) 2001-10-24 2012-09-11 Emcore Solar Power, Inc. Multijunction solar cell with a bypass diode
US6864414B2 (en) * 2001-10-24 2005-03-08 Emcore Corporation Apparatus and method for integral bypass diode in solar cells
US7071407B2 (en) 2002-10-31 2006-07-04 Emcore Corporation Method and apparatus of multiplejunction solar cell structure with high band gap heterojunction middle cell
US7709287B2 (en) 2002-10-31 2010-05-04 Emcore Solar Power, Inc. Method of forming a multijunction solar cell structure with a GaAs/AIGaAs tunnel diode
FR2863775A1 (fr) * 2003-12-15 2005-06-17 Photowatt Internat Sa Module photovoltaique avec un dispositif electronique dans l'empilage lamine.
EP1544922A1 (fr) * 2003-12-15 2005-06-22 Photowatt International S.A. Module photovoltaique avec un dispositif électronique dans l'empilage laminé
US8536445B2 (en) 2006-06-02 2013-09-17 Emcore Solar Power, Inc. Inverted metamorphic multijunction solar cells
US10553740B2 (en) 2006-06-02 2020-02-04 Solaero Technologies Corp. Metamorphic layers in multijunction solar cells
US10026860B2 (en) 2006-06-02 2018-07-17 Solaero Technologies Corp. Metamorphic layers in multijunction solar cells
US8686282B2 (en) 2006-08-07 2014-04-01 Emcore Solar Power, Inc. Solar power system for space vehicles or satellites using inverted metamorphic multijunction solar cells
US8513518B2 (en) 2006-08-07 2013-08-20 Emcore Solar Power, Inc. Terrestrial solar power system using III-V semiconductor solar cells
US10381505B2 (en) 2007-09-24 2019-08-13 Solaero Technologies Corp. Inverted metamorphic multijunction solar cells including metamorphic layers
US8895342B2 (en) 2007-09-24 2014-11-25 Emcore Solar Power, Inc. Heterojunction subcells in inverted metamorphic multijunction solar cells
US9231147B2 (en) 2007-09-24 2016-01-05 Solaero Technologies Corp. Heterojunction subcells in inverted metamorphic multijunction solar cells
US8946608B2 (en) 2008-02-01 2015-02-03 Suncore Photovoltaics, Inc. Solar tracking system
US9331228B2 (en) 2008-02-11 2016-05-03 Suncore Photovoltaics, Inc. Concentrated photovoltaic system modules using III-V semiconductor solar cells
US9923112B2 (en) 2008-02-11 2018-03-20 Suncore Photovoltaics, Inc. Concentrated photovoltaic system modules using III-V semiconductor solar cells
US8890044B2 (en) 2008-10-24 2014-11-18 Suncore Photovoltaics, Incorporated Solar cell system
US9012771B1 (en) 2009-09-03 2015-04-21 Suncore Photovoltaics, Inc. Solar cell receiver subassembly with a heat shield for use in a concentrating solar system
US9806215B2 (en) 2009-09-03 2017-10-31 Suncore Photovoltaics, Inc. Encapsulated concentrated photovoltaic system subassembly for III-V semiconductor solar cells
US9236503B2 (en) 2010-10-22 2016-01-12 Sharp Kabushiki Kaisha Solar cell
WO2012053471A1 (fr) 2010-10-22 2012-04-26 シャープ株式会社 Cellule de batterie solaire
US9508876B2 (en) 2011-07-12 2016-11-29 Astrium Gmbh Solar cell and solar cell assembly
EP2546889A1 (fr) * 2011-07-12 2013-01-16 Astrium GmbH Cellule solaire et ensemble de cellule solaire
US10644180B2 (en) 2011-07-12 2020-05-05 Airbus Defence and Space GmbH Solar cell and solar cell assembly
US10153388B1 (en) 2013-03-15 2018-12-11 Solaero Technologies Corp. Emissivity coating for space solar cell arrays
CN113169241A (zh) * 2018-11-30 2021-07-23 瑞士电子显微技术研究与开发中心股份有限公司 光伏模组
CN113169241B (zh) * 2018-11-30 2022-07-08 瑞士电子显微技术研究与开发中心股份有限公司 光伏模组

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