Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/20—Light-sensitive devices
  • H01G9/2068—Panels or arrays of photoelectrochemical cells, e.g. photovoltaic modules based on photoelectrochemical 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
  • 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
  • H01L31/0465—PV modules composed of a plurality of thin film solar cells deposited on the same substrate comprising particular structures for the electrical interconnection of adjacent PV cells in the module
• • 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
  • Y02E10/542—Dye sensitized solar cells
• • 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
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the invention relates to a power generating element for conversion of light into electricity and to a process for manufacturing thereof.
• a photovoltaic cell (PV) or solar cell converts light directly into electrical power. It exploits the photovoltaic effect in junctions between semiconductor materials.
• Photovoltaic cells are traditionally manufactured using silicon-based technology with Si substrates and semiconductor processes. Other technologies include CIGS (Copper, Indium, Gallium, Selenide) and dye sensitised titania or organic type of solar cells.
• One of the purposes of a series connection structure in large-area solar cells is to obtain high output voltage from a large-area solar cell. In addition it is important to reduce the joule losses in electrodes. If one cell of the solar cell is formed on the entire surface of a substrate without forming a series connection structure, generated carriers may migrate over a long distance in the electrode and the metallic electrode on the rear side down to a lead take-out point disposed at the end of a solar cell. Because the metallic electrode is characterised by low resistance, joule loss caused by current flowing through the metallic electrode may be neglected. However, sheet resistance in the conductive thin-film can be significant; therefore, joule loss caused by current flowing over a long distance in the transparent electrode layer is also significant. For this reason, conventional technology usually disperses a large- area solar cell into several strip-formed cells, and constructs these cells with a width from 4 mm to 20 mm.
• WO03079448 describes the state of the art in this technology, and relates to a self-adjusting serial circuit of thin layers and method for production thereof.
• the invention relating to WO03079448 is characterised in that electrically conducting conductor tracks are applied to a substrate whereupon several main deposit layers of conducting, semi-conducting or insulating materials are applied to the substrate. The application of the layers is carried out at various angles of incidence to the surface of the substrate.
• adherence between various layers might be adversely affected during subsequent manufacturing steps and/or use, e.g. in high temperature conditions.
• An object of the invention is to provide for a series connection and process for manufacturing a series connection for photovoltaic cells, in particular a power generating element for conversion of light into electricity, which have simplified fabrication process steps so as to afford a cost effective and energy-efficient product.
• Another object is to provide a power generating element and manufacturing process thereof, wherein one or more of the above mentioned drawbacks are reduced or eliminated.
• a series connection for a series of photovoltaic (PV) cells comprising: a formed metal substrate having a series of spaced elongate protrusions extending upwardly on the substrate; at least one insulating layer over the substrate; active layers between the elongate protrusions; and at least one conducting layer over the substrate to provide conducting channels between the substrate and an overlying layer which is an active part of the PV cell.
• PV photovoltaic
• the invention provides a power generating element for conversion of light into electricity, the element comprising a plurality of photovoltaic cells, a support for individually supporting the photovoltaic cells, wherein the support comprises a metal substrate having integrally formed recesses for receiving photovoltaic cells.
• the support for supporting the plurality of photovoltaic cells comprises a metal substrate.
• This metal substrate is provided with recesses.
• Each recess contains a photovoltaic cell.
• the recesses are integrally formed in the substrate.
• the photovoltaic cells can be connected in parallel. Alternatively, the photovoltaic cells are serially connected.
• the element comprises: a substrate having a series of spaced parallel protrusions extending upwardly on the substrate, the protrusions being integrally formed with the substrate made of metal, and neighbouring protrusions defining recesses between them; at least one insulating layer over the protrusions and recesses; spaced apart conductive parts leaving free a gap between neighbouring conductive parts, each conductive part (at least) partially covering each of a protrusion and adjacent recess; active layers of a photovoltaic cell in each recess on the respective conductive part; spaced apart front electrode elements on the uppermost active layer, a front electrode element being in electrical connection with the conductive part of one adjacent protrusion.
• the protrusions or ridges are integral with the metal substrate.
• Such integral protrusions can be easily provided by mechanical forming operations, that can be applied to strip metal. Again because the protrusions are integral, these protrusions can not become detached or otherwise removed or repositioned during subsequent manufacturing processes or during use in high temperature conditions. Partial detachment or repositioning may happen when the adherence between separately applied protrusions e.g. by (screen) printing and the substrate leaves something to be desired.
• Neighbouring protrusions define a recess.
• the substrate having the protrusions and recesses serves as a support for the series of photovoltaic cells, which are constructed in these recesses.
• the protrusion itself is a useful tool for structuring a connection in serially connected photovoltaic cells as will be explained hereinbelow.
• the insulating layer is a coating made from vitreous enamel, glass or glass-ceramic, ceramic nitride or oxide, sol-gel or polymer.
• the insulating layer is applied using printing, sputter deposition, plasma deposition, chemical vapour deposition (CVD) or physical vapour deposition (PVD) processes, sol-gel, electrochemical (masking) deposition processes or lamination.
• the substrate is a metal panel or strip, advantageously made from carbon steel , low or ultra low carbon steel, stainless steel, aluminised steel, ECCS, aluminium or titanium.
• the conductive parts are made from a material selected from the group comprising transparent conductive oxide (TCO) coating, preferably indium- doped tin oxide (ITO), zinc oxide (ZnO), aluminium or molybdenum.
• TCO transparent conductive oxide
• ITO indium- doped tin oxide
• ZnO zinc oxide
• the conductive parts are applied as a conducting layer.
• This layer can be applied using printing, sputter deposition, plasma deposition, chemical vapour deposition (CVD) or physical vapour deposition (PVD) processes, sol-gel, electrochemical (masking) deposition processes or lamination.
• the conducting layer is interrupted, e.g. by lasering, or removing material, thereby creating a gap between adjacent conductive parts.
• this gap is filled with an insulating material in order to obtain a flush surface serving as a support and scaffold for building the subsequent active layers of a photovoltaic cell.
• a conductive part is a back contact.
• the active layer comprises porous titanium and electrolyte.
• the active layer comprises CIGS or CdS.
• a protrusion or ridge has a bus bar as an electrical contact.
• the front electrode elements are made from a transparent material.
• a process for manufacturing a series connection for a series of (PV) cells comprising: - providing a formable metal substrate; forming a series of spaced elongate protrusions extending upwardly on the substrate; applying at least one insulating layer over the substrate; applying active layers between the elongate protrusions; and - forming at least one conducting layer over the substrate to provide conducting channels between the substrate and an overlying layer which is an active part of the PV cell.
• a second aspect of the invention relates to a process for manufacturing a power generating element for conversion of light into electricity, the process comprising: providing a metal substrate; forming a number of recesses in the metal substrate; and manufacturing a photovoltaic cell in each recess.
• the invention provides a process for manufacturing a power generating element for conversion of light into electricity, the process comprising: providing a metal substrate; - forming a series of spaced parallel protrusions extending upwardly on the substrate, neighbouring protrusions defining recesses between them; applying at least one insulating layer over the protrusions and recesses; at least partially covering each of a protrusion and adjacent recess with electrically conductive parts, such that a gap is formed between neighbouring conductive parts; applying active layers of a photovoltaic cell in each recess on the respective conductive part; providing spaced apart front electrode elements on the uppermost active layer such that a front electrode element is in electrical connection with the conductive part on one adjacent protrusion.
• the process permits the use of low cost substrates and the use of materials that are readily formable in accordance with the invention. Further, the process permits a continuous production in a continuous production line.
• the spaced parallel protrusions are formed substantially upright relative to the substrate.
• the protrusions are formed by a forming operation including metal- embossing, coining, engraving at one or both sides, profiling, laser marking, pressing, machining or mechanical grinding/sharpening.
• the PV cells are encapsulated by an encapsulating layer, e.g. by applying a laminate on top of the structure.
• an encapsulation is useful, if a non-solid active PV layer is used.
• the bottom of a recess, the upstanding walls of the protrusions including their insulating layer and conductive parts. define a container containing the active PV layers, while the encapsulating layer seals the container like a lid or cap.
• Figure 1 refers to the formation by forming operations of an upright ridge or protrusion in a metal substrate
• Figure 2 shows that the metal substrate is electrically insulated from the subsequently applied layers which form the photovoltaic cells
• Figure 3 shows the application of the scribing process to form scribed regions
• Figure 4 shows an electrically conductive layer (not shown) is deposited so as subsequently to form bus bars.
• Figure 5 shows an embodiment of the series connection indicating the flow of current in the PV cell series connection.
• Figure 6 shows an embodiment of the series connection with TCO and electrolyte materials.
• substrate 10 is a metal panel upon which the layers of the PV cell are applied in accordance with the invention.
• a metal substrate 10 which can be shaped or deformed using processes such as forming operations, metal-embossing, coining, engraving at one or both sides, profiling, laser marking, pressing, machining or mechanical grinding/sharpening.
• Hydro-forming is an alternative process which may be used to deform the substrate in accordance with the invention.
• This forming or shaping step provides the substrate 10 with ridges or protrusions 12 which are formed substantially vertical to the substrate surface 13 typically having a height within the range 5-200 microns with a variability of no more than 10%.
• the formation of the spaced apart parallel protrusions 12 along the substrate 10 may span the entire panel or may be truncated towards the edge of the panel so as to leave sufficient space at the edges for bonding subsequent overlying encapsulating layers.
• the protrusions 12 function as a support for electrically conductive tracks. Inter- protrusion spacing is of the order 10-100 mm, the width dimension of the ridge or protrusion being of the order 0.5-5 mm, while the upright walls 15 of the protrusions with respect to the substrate surface 13 are substantially vertical and preferable at ninety degrees to the surface 13. This angle could also deviate variably from ninety degrees.
• the walls 15 facing each other, of neighbouring protrusions 12 define recesses 14.
• the flat surface 13 is the bottom 21 of the recess 14.
• a suitable metal for the substrate 10 in accordance with the invention is carbon steel, preferably steel strip or sheet material, (ultra) low carbon steel or aluminium.
• Other materials such as glass or ceramics tend to be expensive and difficult to form.
• an insulating coating 16 can be formed from enamel such as vitreous enamel, glass or glass-ceramic, ceramic nitride or oxide such as chromium oxide, sol-gel or polymer and can be applied by printing, sputter deposition, plasma deposition, chemical vapour deposition (CVD) or physical vapour deposition (PVD) processes, in addition to sol-gel, electrochemical (for masking) deposition processes or lamination.
• an additional suitable candidate for the substrate includes electro-coated chromated steel (ECCS).
• a thin layer of amorphous SiO2 using CVD may be used as the insulating layer or stabilised zirconium oxide.
• Alternative materials include high silicon steel or high aluminium steel.
• Figure 2 shows that the metal substrate 10 is electrically insulated by insulating layer 16 from the subsequently applied layers which form the photovoltaic cells.
• the function of this insulating layer 16 is to provide a corrosion protective layer or diffusion barrier which is preferentially resistant to high temperatures, for example up to 550 0 C, and resistant to corrosive atmospheres.
• Insulating layer 16 can also be used as an effective substrate for deposition of a conducting coating layer 18 thereon to function as the back-contact.
• the insulating layer 16 should be resistant to the conditions of subsequent mechanical, chemical or thermal removal processes such as scribing of the conducting layer 18 applied on top of it, in order to provide interruptions or gaps 20 in the conducting layer 18 so that spaced apart conductive parts 19 are obtained.
• the layer 18 should not decompose when an electrical potential is created by the operation of the photovoltaic cells. Furthermore, the conductive coating 18 should not be sensitive to the electrolyte when using a dye sensitized titania (Graetzel) cell.
• the electrically conductive parts 19, serving as the back contact may include a transparent conductive oxide (TCO) coating such as indium-doped tin oxide (ITO), zinc oxide (ZnO), aluminium, titanium or molybdenum.
• TCO transparent conductive oxide
• ITO indium-doped tin oxide
• ZnO zinc oxide
• aluminium titanium or molybdenum.
• CVD is a suitable process for depositing TCO layers as it is conducive to obtaining the optimal electrical conductivity.
• this electrically conductive deposit is typically about 1 micrometer in thickness.
• the electrically conductive Iayer18 may be a metallic coating, a metal foil, an electrically conductive polymer, or a polymer that can be reinforced with the addition of components so as to induce electrical conductive properties thereto, to the desired extent.
• figure 3 shows the application of a scribing process to form gaps
• the conductive coating 18 is a metallic material with a lower thermal expansion coefficient than the substrate metal 10 (for example if the back electrode is titanium foil and the substrate is steel), then gaps 20 or single blade cuts of the scribing process mentioned above can be performed at a lower temperature, e.g. using a laser. As the metallic material warms up to room temperature, the substrate 10 will expand more than the metallic material and the gaps
• the metal substrate 10 and the foil should be joined together at low temperatures.
• the scribing/cutting step forming the gaps 20 in the conductive coating 18 is followed by the application of an insulating element 30 in the gaps 20 and deposition of additional components generally indicated by reference numeral 22 of the solar cell as shown in figure 4.
• an electrically conductive layer (not shown) is deposited so as subsequently to form bus bars40, and in the inter- protrusion recesses 14 between the upright ridges the additional components of the solar cell are deposited with materials such as porous titania and electrolytes.
• the bus bars 40 can be applied e.g. by screen printing of a precursor or pre-sinter paste, which then reacts further with the desired active layer under the influence of temperature and atmosphere.
• CIS is Chalcopyrite which has the general formula Cu(In, Ga)(Se, S) 2 and is used in thin film technology for manufacturing solar cells. In such solar cells the chalcopyrite semiconductors acts as absorber layers for polycrystalline thin film solar cells.
• a TCO layer is sputtered over the profile shown in figure 4, and cuts or scribes are made at regular intervals into the TCO layer for electrical interruptions.
• the back contact and front contacts TCO could also be applied using shadowing processes in the deposition of these layers so as to produce the electrical interruptions, provided that the layers are deposited obliquely relative to the substrate.
• the TCO is applied to a laminate, which is then connected to the solar cell via the top of the upright protrusions 12 having electrically conductive bus bars 40 thereon.
• Figure 5 shows an embodiment of the series connection indicating the flow of current in the PV cell series connection.
• the arrows show the resulting current flow.
• the current is conducted into the conductive parts 19 acting as back contact and via the active layer 22 into the front electrode elements 24. From there, it flows once again through a bus bar or conductor track 40 into the next conductive part (back contact) and from there, again via the front electrode element, into the next conductor track.
• a substrate 1 10 having an insulating layer 116.
• a conductive part 118 (back contact) deposited on the insulating layer 116 is connected to front electrode element 124 at the top of the protrusion 112 while the inter-protrusion region or recess 1 14 comprises porous titania 122a and electrolyte 122b.
• the arrangement is further encapsulated or packaged by covering the front surface of the element with, for example, a transparent material such as transparent foil 150.
• the encapsulating materials are applied over the entire PV panel shown in figure 6, and the bonding of the foil to the PV cell arrangement takes place at the edges of the panel 100.

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• Condensed Matter Physics & Semiconductors (AREA)
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• 2008
  • 2008-02-01 WO PCT/EP2008/051301 patent/WO2008092963A2/en active Search and Examination
  • 2008-02-01 EP EP08708605A patent/EP2118929A2/de not_active Withdrawn

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