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
  • H01L31/02016—Circuit arrangements of general character for the devices
  • H01L31/02019—Circuit arrangements of general character for the devices for devices characterised by at least one potential jump barrier or surface barrier
  • H01L31/02021—Circuit arrangements of general character for the devices for devices characterised by at least one potential jump barrier or surface barrier for 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
  • H01L31/0445—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
  • H01L31/046—PV modules composed of a plurality of thin film solar cells deposited on the same substrate
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
  • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
  • H02S40/30—Electrical components
  • H02S40/32—Electrical components comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
• • 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

• the present invention relates to the field of photovoltaic devices and more particularly to devices comprising photovoltaic cells of so-called thin film technologies.
• the invention also relates to the manufacture of a thin film vo ltaic photo device.
• a photovoltaic device comprises one or more photovoltaic cells (PV) connected in series and / or in parallel.
• a photovoltaic cell essentially consists of a diode (pn junction or pin) made from a semiconductor material. This material has the property of absorbing light energy, a significant part of which can be transferred to charge carriers (electrons and holes).
• the potential difference (open circuit voltage, V oc ) and the maximum current (short circuit current, I cc ) that the photovoltaic cell can supply are a function of both the materials constituting the whole cell and the conditions surrounding this cell (including illumination through spectral intensity, temperature, ).
• V oc open circuit voltage
• I cc short circuit current
• Thin film photovoltaic cell technologies have many advantages. They enable high throughput manufacturing processes for large areas over crystalline silicon technologies.
• the thin-film photovoltaic cells also have a good energy efficiency when they are assembled in modules.
• Photovoltaic module means the assembly of a plurality of photovoltaic cells.
• the module can also be associated with management electronics typically comprising a static converter (CS) and possibly an electronic search command of the maximum power point (or MPPT or Maximum Power Point Tracker in English terminology).
• CS static converter
• MPPT Maximum Power Point Tracker in English terminology
• Figure 1 shows the steps of a conventional manufacturing process of a thin-film photovoltaic cell device.
• the thickness proportions of the different layers are not respected in the diagram of FIG.
• the various materials are deposited in thin films on a substrate 10 by PVD (Physical Vapor Deposition) or by PECVD (Plasma Enhanced Chemical Vapor Deposition), or by cathode sputtering or by LPCVD (Low Pressure Chemical Vapor Deposition).
• PVD Physical Vapor Deposition
• PECVD Pullasma Enhanced Chemical Vapor Deposition
• cathode sputtering or by LPCVD (Low Pressure Chemical Vapor Deposition).
• LPCVD Low Pressure Chemical Vapor Deposition
• FIG. 1 shows a first step (a) in which a first electrode 11 is deposited on a substrate 10.
• substrate 10 is the part that supports the active elements of the photovoltaic cell.
• the substrate may be rigid such as a glass or flexible plate such as a sheet of polymer or stainless steel or titanium; it may be transparent or opaque depending on whether it will be placed in the path of the incident or non-incident light with respect to the active layers.
• the substrate may also be chosen so that it constitutes at least one of the end product encapsulation plates, for example a glass substrate in the case of a rigid photovoltaic module.
• the substrate glass, polymer or metal
• the substrate that is best suited to the deposition of the different active layers of the device that they wish to manufacture.
• the first electrode 11 may be composed of a light-transparent oxide layer, such as indium tin oxide (ITO for Indium Tin Oxide) or transparent conductive oxides (OTC) such as oxide of indium (In 2 O 3 ), zinc oxide (ZnO) doped with aluminum or tin (SnO 2 ) doped with fluorine for example. It is possible to deposit a rear reflector layer directly on the substrate 10 before the first electrode (referenced 20 in FIG. 2), especially when the substrate 10 is transparent and the incident light enters the cell through the face opposite to the substrate .
• the rear reflector layer may be a layer of copper, silver or aluminum, for example.
• FIG. 1 shows a second step (b) in which the layer of the first electrode 11 is segmented to delimit strips which will constitute as many individual diodes on the same panel defined by the substrate 10, the surface of the electrodes imposing the maximum current which will be delivered by the diode thus constructed.
• the segmentation is typically carried out by laser etching, for example with an Nd-YAG type laser (acronym for neodymium-doped yttrium aluminum garnet).
• FIG. 1 shows a third step (c) in which the active layers 15 are deposited.
• the active layers 15 For example, thin films of hydrogenated amorphous silicon (a-Si: H), polymorph (pm-Si: H) or microcrystalline silicon ( ⁇ c-Si: H) may be deposited to form one or more superimposed PN or PIN junctions.
• the man of profession will choose any material suitable for the manufacture of a PN or PIN junction according to the available industrial equipment and / or the needs in photoelectric output.
• the active layers 15 fill the interstices between the strips of the first electrode 11, thereby isolating each electrode segment.
• FIG. 1 shows a fourth step (d) in which the active layers 15 are segmented until the first electrode 11 is exposed.
• the segmentation of the active layers 15 is shifted with respect to the segmentation of the first electrode 11 to enable a contact between the second electrode to be deposited in step (e) and the first electrode 11, thus ensuring the series of diodes formed by the adjacent strips.
• placing the diodes in series on a single panel makes it possible to reach a higher voltage equal to the sum of the elementary voltages of each diode placed in series.
• the segmentation of the active layers 15 is typically performed by laser etching, for example with an Nd-YAG type laser.
• FIG. 1 shows a fifth step (e) in which a second electrode 12 is deposited to frame, with the first electrode 11, the active layers 15 of the cell.
• the second electrode 12 may be of the same composition as the first electrode 11 or of a different composition; it can be composed of Indium Etain Oxide (ITO) or any Transparent Conductive Oxide (OTC) for example.
• ITO Indium Etain Oxide
• OTC Transparent Conductive Oxide
• the second electrode 12 may be further covered with a rear reflector if the incident light enters the cell through the substrate 10; the second electrode 12 may also serve as a rear reflector with a suitable composition, for example if it is composed of an alloy of ITO, silver and nickel.
• the second electrode 12 fills the segmentation interstices of the active layers 15, ensuring the series of adjacent bands.
• FIG. 1 shows a sixth step (f) in which the second electrode 12 is segmented until the active layers are exposed.
• the segmentation of the second electrode 12 is further shifted with respect to the segmentation of the active layers 15 and with respect to the segmentation of the first electrode 11 to delimit, with the first segmentation of the step (b), the active zones of the bands of individual diodes.
• the segmentation of the second electrode 12 is typically carried out by laser etching, for example with an Nd-YAG type laser, or by mechanical etching.
• Figure 2 summarizes in a flowchart the manufacturing steps described with reference to Figure 1.
• the substrate 10 is first washed and checked to verify that there is no crack or dust or defect on the surface of the substrate or even check that the substrate is not broken simply.
• a reflector 20 can then be deposited; then the first electrode 11.
• the first electrode 11 is then textured, for example by annealing to obtain the same crystalline orientation of the deposited molecules, and segmented.
• the quality of the segmentation - fineness, straightness, depth, ... - is controlled and the substrate must once again be washed to remove the metal residues of the etching.
• the active layers 15 - PIN or other junctions - are deposited and segmented then the second electrode 12 is deposited and segmented.
• a final check is then made.
• the active layers and the layer of the first electrode can be segmented together and Insulating ink can be screen printed. Then the second electrode is deposited and segmented. Finally, a contact grid, silver for example, is screen printed on the second electrode and a remelting step of this grid ensures the series of two adjacent photovoltaic strips. The reflow of the metal layer is provided by laser.
• segmentation reduces the useful area of the device. Indeed, all areas that are destroyed by a segmentation stripe are unusable for the production of photovoltaic energy.
• the active area of a photovoltaic cell is delimited by the first and third segmentation stripes. Thus, for example, for 12 mm wide strips, a loss of about 5 to 6% of area, and therefore of intensity delivered by the cell, is due to segmentation.
• FIG. 3 shows a schematic cross-sectional view of a piece of thin-film photovoltaic device with a series interconnection of adjacent vo ltaic photo cells.
• the dimensions of the different layers and the segmentation scratches are not to scale in FIG. 3.
• FIG. 3 shows the substrate 10, the first electrode 11, the active photovo ltaic layers 15 and the second electrode 12.
• FIG. also shows a first segmentation line 1 for electrically isolating two adjacent photovoltaic cells; this first scratch 1 is hollowed out in the first electrode 11 and the active layers 15 and filled with insulating ink.
• a second segmentation scratch 2 is hollowed out in the active layers 15 and filled with the material of the second electrode 12 during the deposition of the latter.
• a third segmentation stripe 3 segments the second electrode 12 in strips. It can be seen in FIG. 3 (black arrow) that the current I of one photovoltaic cell is led to the next by the second electrode, the second stripe and the first electrode. Each photovoltaic cell delimited by the first and third scratches 1, 3 is thus connected in series with the adjacent cell by means of the second stripe 2.
• Serialization of the cells of a photovoltaic device is necessary to increase the output voltage of the device to voltage values compatible with the continuous or alternating external loads to which the device is intended to be connected. Segmentation of the thin layers of a photovoltaic device, however, is an expensive step in time and equipment and reduces the useful surface of the device. There is therefore a need for a method of manufacturing a thin-film photovoltaic device that allows improved manufacturing efficiency and limits the dead surfaces of the device.
• the invention proposes to limit or even eliminate the laser segmentation step in the method of manufacturing a thin-film photovoltaic device; one or a few large cells occupy the entire surface of the device and provide a large current but with a limited voltage. At least one static converter is placed at the terminals of each cell to decrease the current and proportionally increase the voltage. It is thus possible to eliminate a constraining step in the method of manufacturing the photovoltaic device by adding a suitable conversion electronics.
• the invention more specifically relates to a photovoltaic device comprising: at least one photovoltaic cell comprising active thin layers deposited on a substrate, said active layers being not segmented; and at least one static converter associated with each photovoltaic cell, in which - each photovoltaic cell provides electrical power with a maximum current and a nominal voltage, and each static converter is adapted to transmit the electric power supplied by the photovoltaic cell to a load by decreasing the transmitted current and increasing the transmitted voltage.
• the static converter is a DC-DC converter (DC / DC) and / or a DC-AC converter (DC / AC).
• the static converter is associated with a management electronics adapted to control the decrease of the transmitted current and the increase of the transmitted voltage.
• the management electronics associated with the static converter may include a search command of the maximum operation (MPPT).
• MPPT maximum operation
• the management electronics can communicate with the load.
• the device comprises a plurality of static converters arranged in series between each photo voltaic cell and the load.
• the device comprises a single photovoltaic cell.
• the active layers of the photovoltaic cell can cover more than 95% of the surface of the substrate.
• the device comprises a plurality of photovoltaic cells connected in parallel to the load each by at least one static converter.
• the invention also relates to a photovoltaic generator comprising a plurality of photovoltaic devices according to the invention connected in series and / or in parallel.
• the invention further relates to a method of manufacturing a photovoltaic device comprising the steps of: fabricating at least one photovoltaic cell by successive deposition of thin layers on a substrate; connect at least one static converter to the terminals of each cell, the method comprising no step of segmentation of the thin layers putting in series several photovoltaic cells elementary.
• FIG. 2 already described, a flowchart of the steps for manufacturing a photovoltaic cell device according to the prior art
• FIG. 3 already described, a diagram of a photovoltaic cell device according to the prior art;
• FIG. 4 a diagram of a photovoltaic device according to the invention;
• FIG. 6 a diagram illustrating the electrical analogy of a photovoltaic cell of reduced surface area with respect to the cell of FIG. 4;
• FIG. 7 a diagram illustrating the electrical analogy of a plurality of photovoltaic cells placed in series
• FIG. 8 a diagram illustrating the electrical analogy of a photovoltaic device according to the invention.
• the invention proposes a thin-film photovoltaic device comprising at least one photovoltaic cell associated with at least one static converter.
• Each photovoltaic cell of the device according to the invention is electrically connected to a load by at least one static converter.
• load is the electrical application for which the photovoltaic device is intended without prejudging its nature (continuous or alternative).
• the photovoltaic device according to the invention may comprise a single photovoltaic cell or several large cells each associated with a management electronics and connected in parallel with the load. On the same panel, the laser segmentations are thus limited or completely eliminated.
• large photovoltaic cell is meant a cell without segmentation of the active layers putting in series several elementary cells. The manufacturing efficiency of the photovoltaic device is thus improved and the dead surfaces are limited.
• Such a "large” cell then delivers a large current, generally greater than the needs of the load, with a limited voltage, generally less than the needs of the load.
• Each static converter is then adapted to reduce the current supplied by the photovoltaic cell to which it is associated by a factor N and to increase the voltage supplied to the load by a factor N at most.
• the power received at the input of the converter, by the cell of the photovoltaic device is substantially equal to the power output by the converter to the load; the output power may be slightly less than the input power due to thermal losses and losses in the converter (due to switching by example).
• the converter converts the energy received from the photo voltaic cell to adapt the output voltage to values compatible with the applications of the load.
• FIG. 4 illustrates a photovoltaic device according to the invention.
• the photovoltaic device according to the invention is described with respect to a single photovoltaic cell. However, it is understood that the device described can be duplicated with several photovoltaic cells and static converters arranged in module and connected in parallel to the load.
• the device of the invention comprises a single photovoltaic cell 60.
• This single thin-film photovoltaic cell comprises a substrate 10, a first electrode 11, active layers 15 constituting at least one junction, and a second electrode 12
• This photovoltaic cell 60 is manufactured according to one of the methods described above with the exception of the segmentation steps of the deposited layers.
• the cell 60 of the device according to the invention has no segmentation stripe; that is to say that its active layers and electrodes are not segmented to form several series cells connected in series as is typically the case in the prior art.
• the active layers 15 of the cell therefore cover almost the entire surface of the substrate 10, more than about 95%. It is nevertheless possible to envisage segmentation to delimit the edges of the cell and set a maximum current.
• the device of the invention furthermore comprises at least one static converter 50 at the terminals of the cell 60.
• the static converter 50 may be a DC-AC converter (DC / AC according to the acronym used in English). ) and / or a DC-DC converter (DC / DC according to the acronym used in English).
• the static converter 50 is adapted to transmit the electrical power supplied by the photovoltaic cell 60 to a load 100 of an external application - battery, electrical network or other.
• the converter 50 of the device according to the invention is adapted to reduce the transmitted current and to increase the transmitted voltage.
• Figure 4 shows that a plurality of converters 50 may be arranged in series.
• the cell 60 provides electrical power with a current depending on the sun and a nominal voltage equal to the threshold voltage of the junction.
• a first converter can transform this power by decreasing the current by a first factor N and increasing the voltage to the maximum of a first factor N; a second converter can then transform this power by further decreasing the current of a second factor N 'and further increasing the voltage to a maximum of a second factor N'.
• Each converter 50 can be associated with a management electronics which controls the current decrease and voltage increase factor.
• the management electronics may be common to the set of converters of a cell. Such electronics can also incorporate a search command of the maximum operating point (MPPT) of the cell.
• MPPT maximum operating point
• the management electronics makes it possible in particular to reprogram the operation of each converter 50, for example if the needs of the load 100 are changing or if a more efficient control law is proposed.
• Such electronics may also detect malfunctions, both at cell level 60 and at converters 50, and interrupt power transmission and / or alert load 100 and / or an outside observer, such as a network supervisor. .
• the transmission of information between the management electronics and the load 100 can be done by line carrier currents (CPL) or by radio link for example.
• CPL line carrier currents
• FIG. 5 schematically illustrates the electrical analogy of a single photovoltaic cell covering the entire surface of a device.
• a photovoltaic cell consists essentially of a diode; its output voltage corresponds to the threshold voltage of the diode and the output current depends directly on the size and the constituent materials of the cell and the surrounding conditions.
• Such a cell can therefore provide a maximum current I cc important, around 150 A for example for active layers of type thin layer of silicon and a surface of the order of Im 2 , with a threshold voltage V oc typically less than 1 V.
• Such an output voltage is generally not compatible with the external loads to which the photovoltaic device is intended.
• the required output voltage is of the order of 12 V.
• the required output voltage is of the order of 240V.
• These voltage values are much higher than can be provided by a single photovoltaic cell covering the entire surface of the device.
• few applications require a current as high as that provided by a single large cell. This is why the photovoltaic devices of the prior art comprise a plurality of cells connected in series. Each cell has a reduced size compared to the total surface of the device; the output current is therefore decreased, but the series setting increases the output voltage.
• Figure 6 (which is outside the invention but presented for purposes of understanding) schematically illustrates the electrical analogy of a cell of a segment of a photovoltaic device. If the photovoltaic device comprises N bands of cells over a whole area identical to that of the device of Figure 5, then the maximum output current I cc will be reduced by a factor N minus the area removed by the scratches; the output voltage of the cell will always be equal to the threshold voltage of the diode constituting the cell.
• FIG. 7 (which is outside the invention but presented for purposes of understanding) schematically illustrates the electrical analogy of the series connection of a plurality of elementary photovoltaic cells of FIG. 6.
• the maximum current I cc remains reduced, because of the reduced surface of each cell, but the output voltage is increased by a factor N by the serialization of the elementary cells.
• the output voltage of the device can then be compatible with the external application.
• the segmentation of the layers of the photovoltaic device is long, expensive and constitutes the point of limitation of the production capacity.
• the series setting of the photovoltaic cells limits the output current to the current of the least lighted cell of the device.
• the invention therefore proposes, as described with reference to FIG. 4, a photovoltaic device comprising a single photovoltaic cell 60 associated with at least one static converter 50.
• FIG. 8 schematically illustrates the electrical analogy of a photovoltaic device according to the invention.
• the photovoltaic cell of the device can be assimilated electrically to a diode; its power characteristic will therefore be identical to that described with reference to FIG. 5 with a nominal output voltage V p corresponding to the threshold voltage of the diode and a maximum output current I cc directly dependent on the size and materials constituting the the cell as well as surrounding conditions.
• the cell of the device according to the invention is however associated with a static converter (DC / DC or DC / AC) which transforms the power supplied by the cell by reducing the current by a factor N and increasing the voltage to the maximum of a factor N.
• the output power of the converter is substantially equal to the input power (a power conversion generates losses even if the latter are limited) but the output voltage could be increased to values compatible with the needs of the charge.
• the photovoltaic cell 60 of the device according to the invention thus provides a large current I cc , which can reach 150 A or more, with a nominal voltage V p low, typically less than 1 V.
• the converter 50 of the device according to the invention provides an increase of this voltage, a factor N which can be between 10 and 50 depending on the application, with a corresponding decrease in current. If the factor of increase of the voltage - decrease of the current - required by the load 100 is important, several converters 50 (DC / DC and / or DC / AC) can be cascaded as illustrated in FIG. so-called Boost, Buck, Buck-Boost or Cuck can be used in the context of the invention.
• the photovoltaic cell 60 of the device according to the invention allows the passage of strong currents without deterioration of the layers of the cell.
• the layers of the electrodes 11, 12 may be adapted in terms of materials and thicknesses to limit resistivity and warming.
• the electrical connection buses 31, 32 intended to collect the current from each electrode 11, 12 of the cell, can be adapted in terms of materials and sections to drive strong currents.
• the present invention is not limited to the embodiments described by way of example.
• the materials cited for manufacturing the different layers of the cell have been given for illustrative purposes only and depend on the processes and the manufacturing equipment used.
• the current and voltage values have been given for illustrative purposes and depend on the type of photovoltaic cell and the load to which the device is intended.

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