WO2015012697A1 - Photo-voltaic cell its manufacture and an assembly of such photo-voltaic cells - Google Patents
Photo-voltaic cell its manufacture and an assembly of such photo-voltaic cells Download PDFInfo
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- WO2015012697A1 WO2015012697A1 PCT/NL2014/050515 NL2014050515W WO2015012697A1 WO 2015012697 A1 WO2015012697 A1 WO 2015012697A1 NL 2014050515 W NL2014050515 W NL 2014050515W WO 2015012697 A1 WO2015012697 A1 WO 2015012697A1
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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
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
- H01L31/022441—Electrode arrangements specially adapted for back-contact solar cells
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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
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
- H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
- H01L31/0516—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module specially adapted for interconnection of back-contact 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
- 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
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- Condensed Matter Physics & Semiconductors (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
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Abstract
Electrical connections of a back contact photo-voltaic cell are made by means of a stack of flexible electrically conductive sheets placed on a semiconductor substrate. A first electrically conductive sheet has first and second openings and third and fourth openings are provided in a combination of a second electrically conductive sheet and an electrically isolating sheet. A stack of these sheets is placed on the substrate, with the first electrically conductive sheet between the electrically isolating sheet and the substrate, and the electrically isolating sheet between the second electrically conductive sheet and the first electrically conductive sheet. The third and fourth openings are aligned with the first and second openings respectively. The third openings have a shape that exposes the first electrically conductive sheet along a perimeter of the first openings that are aligned with the third openings, and the fourth openings having a shape that covers a perimeter of the second openings that are aligned with the fourth openings. Electrical connection material is applied through the first and third openings to connect the substrate to the first electrically conductive sheet, and through the second and fourth openings to connect the substrate to the second electrically conductive sheet.
Description
Title: Photo-voltaic cell its manufacture and an assembly of such photovoltaic cells Field of the invention
The invention relates to a photo-voltaic cell and a method of manufacturing a photo-voltaic cell, as well as an assembly of such cells. Background
A photovoltaic cell produces an output voltage between base and emitter areas on the surface of a body of semi-conductor material. To make use of this voltage and the associated currents, external electrical
conductors are used in a connection from the base and emitter areas to other cells in a cell assembly or to the output terminals of the cell (as used herein, "external" electrical conductors are conductor structures that are formed before they are applied to the semi-conductor body, i.e. not pastes or other material etc that are formed into structures during or after application to the semi-conductor body). In a "back contact" photovoltaic cell, first and second external electrical conductors are connected to the back surface of the semi-conductor body, or conductive material that has been deposited on the body. In the following the semi-conductor body, or conductive material that has been deposited on the body will be collectively referred to as the substrate or body.
PCT/NL2011/050547 and DE 102008044910A1 describe photovoltaic cells wherein conductive sheets are used as first and second electrical conductors. When connections to the substrate are made at many points the use of continuous sheets, rather than a network of conductor lines, may reduce complexity and it may improve conductivity. However, it requires that the outermost sheet be connected to the substrate through
openings in the innermost sheet and that electrical isolation be provided between the sheets out side the openings and possibly at selected locations between the sheets and the substrate.
Various alternative methods may be used to connect the sheets to the substrate. In one alternative, connection material such as a conductive adhesive or solder is applied first to the sheets and/or the substrate and the sheets are attached to the substrate with the connection material. The conductive sheets and an isolation sheet between the conductive sheets may be applied one by one or as a composite sheet that contains two or more of the individual sheets attached to each other.
These alternatives have the problem that the height of the connection material is very critical, especially where it is used to connect to the outermost sheet trough the openings in the innermost sheet. When the sheets are applied to the substrate the connection material may spread out. This entails a risk of short circuit between the sheets, which increases with increasing height of the connection material. Moreover, since the outer sheet is closed, it makes it more difficult to position the openings of the first sheet over the contacts of the cell. Once the sheet is attached it is hard to repair failed contacts, e.g. open-circuit contacts. This risk may put limits on the minimum size of the openings and the number of openings that can be used. On the other hand, when the height of the connection material in the openings is less than the thickness of the innermost sheet and the isolation sheet, there may be open circuits between the outermost sheet and the substrate.
Summary
Among others, it is an object to provide for a way of applying connection material to connect external conductor layers to the semi-
conductor body of the photo-voltaic cell that reduces the risk of open and/or short circuits.
A method according to claim 1 is provided. This method allows for the application of electrical connection material in one step to form two types of connection to the semi-conductor body. In an embodiment a stack of sheets including at least two electrically conductive sheets is used, with one or more electrically isolating sheets between the electrically conductive sheets. Openings are provided through the stack, each opening through the stack comprising aligned openings in the electrically conductive sheets and the one or more electrically isolating sheets.
Different types of opening through the stack are used, for making electrical contact to different electrically conductive sheets in the stack. In openings through the stack for contacting an electrically conductive sheet in the stack an the opening in that electrically conductive sheet has a smaller size than the openings in the electrically conductive sheets, if any, above it in the stack, so that the electrically conductive sheet is exposed along at least part of the perimeter of its opening (as used here "above" means at greater distance from the semi-conductor body). Different types of opening through the stack are used, wherein different ones of the electrically conductive sheets have the opening of smaller size.
In a photo-voltaic cell, the stack is located on a substrate that comprises the semi-conductor body of the photo-voltaic cell. The openings of the different types may be located over areas of the substrate that are used to contact different ones of the base and emitter of the substrate
respectively, directly or via base and/or emitter contact electrodes on the substrate. Openings of the first one of the different types may be located over areas for contacting the base and openings of the second one of the different types may be located over areas for contacting the emitter or vice versa. Electrical connection material in the openings may be directly or indirectly in electrical contact with the base and emitter.
The stack is provided on a substrate that comprises the semiconductor body of the photo-voltaic cell. That is, the sheets, including the openings, exist before they are placed on the substrate. Thus simple techniques for making the openings can be used. The stack may be provided by placing the sheets successively on the substrate, or by pre-stacking (e.g. laminating) them and placing the pre-stacked sheets on the substrate together as a stack. The sheets may be of flexible material, so that their cross -sectional shape, as seen in cross-section through the substrate and the sheets, is only determined by the substrate.
Electrical connection material may be applied to all openings through the stack on the substrate in a single step. In an embodiment, the electrical connection material comprises metal grains in a paste or liquid matrix. Use of the openings of different type makes it possible to connect different areas of the substrate to different electrically conductive sheet using the same step of application of electrical connection material. The substrate may contain areas of conductive material on the semi-conductor body which are part of the connections to the semi-conductor body, the openings through the stack being provided over these areas.
In an embodiment a further electrically isolating sheet is placed on the outermost electrically conductive sheet, with an aligned opening that reaches at least to the edge of the opening of the outermost electrically conductive sheet in those types of opening where the outermost electrically conductive sheet does not have the smallest size. This prevents accidental contact between the electrical connection material with the outermost electrically conductive sheet.
In an embodiment electrical connection material is applied on the further electrically isolating sheet and in the further holes and swept off the further electrically isolating sheet outside the further holes.
In an embodiment the electrical connection material is printed in islands located in the openings, extending over the exposed perimeter. This
makes it possible to use a minimum of electrical connection material and reduce accidental short circuits.
Brief description of the drawing
These and other objects and advantageous aspects will become apparent from a description of exemplary embodiments, with reference to the following figures.
Figure 1, 1a show cross-sections through photo-voltaic cells Figure 2 shows a plane view of the photo-voltaic cell
Figure 3, 3a show cross-sections through an opening of a first type
Figure 4 shows cross-section through an opening of a second type
Figure 5a-c show a connection between photo-voltaic cells
Figure 6 shows an array of photo-voltaic cells
Figure 7a shows an array of photo-voltaic cells
Figure 7b, c shows conductor sheets for cells in an array Detailed description of exemplary embodiments
Figures 1, 1a show a cross-sections through a photo-voltaic cell, comprising a substrate 10, which comprises a semi-conductor body optionally with metallization and coatings, and a plurality of sheets 12, 14, 16, 17 and electrical connection material 18 (only part of a cell shown and the ratio of the horizontal and vertical directions is not to scale). The sheets may be layers of foil that are not integrated with substrate 10, so that they can be made as preformed sheets before they are placed on the substrate. The sheets include at least a first electrically conductive sheet 12, a second electrically conductive sheet 14, an electrically isolating sheet 16, and a
further electrically isolating sheet 17. For the sake of clarity, sheets 12, 14, 16, 17 are depicted at a distance from each other and from substrate 10, but it should be understood that they will be in contact with each other. Second electrically conductive sheet 14, electrically isolating sheet 16 and first electrically conductive sheet 12 lie successively between further electrically isolating sheet 16 and substrate 10. Electrical connection material 18 in contact with areas on substrate 10 is present through aligned openings in first electrically conductive sheet 12, electrically isolating sheet 16, second electrically conductive sheet 14, and further electrically isolating sheet 17. By way of example, only two openings with electrical connection material 18 are shown, but it should be understood that more openings may be present.
Figure la shows an embodiment wherein a inner electrically isolating sheet 12a is provided between first electrically conductive sheet 12 and substrate 10. Inner sheet 12a may be a thermoplastic polymer sheet. An ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), silicone, ionomer or thermoplastic urethane (TPU) sheet may be used, which are known to attach substrate 10 without trapping air. If substrate 10 contains
electrically exposed areas at locations where contact to first electrically conductive sheet 12 is undesirable, further sheet 12a may be used to prevent such contact.
Figure 2 shows a plane view of the photo-voltaic cell, comprising further electrically isolating sheet 17 and areas of electrical connection material 18 through the openings. Further electrically isolating sheet 17 is the outermost of the sheets. A density in a range of 0.1 to 30 openings per square millimeter may be used for example for a back -junction point-contact cell. A density in a range of .4 and 50 opening per square decimeter can be used for metal wrap through cell , emitter wrap through cells and
interdigitated back contact cells with multiple contacts. By way of example a rectangular array of openings with circular areas of electrical connection material 18 is shown, but it should be understood that any pattern may be
used and that the areas of electrical connection material 18 may have different shape: they may extend along a line, e.g. a straight line, for example.
As is usual for example in solar cells, substrate 10 may comprise doped semi-conductor material (Si for example) of a first conductivity type (e.g. n-type) with an area of differently doped semi-conductor material at its surface, which may form an emitter or surface field area, with enhanced doping of the first conductivity type or doping of an opposite conductivity type (e.g. p-type) respectively. Such layers may be realized by adding doping to the semi-conductor material or adding a layer on the semi-conductor material.
Substrate 10 may have a pattern of emitter and surface field areas at its surface on the side where sheets 12, 14, 16, 17 are present, the electrical connection material 18 through different openings contacting different ones of the emitter and surface field areas. In another embodiment an emitter layer and a surface layer may be present at mutually opposite surfaces first and second surfaces of substrate 10, with through holes from the second surface to the first surface to isolated contact islands at the first surface, the through holes being filled with conductor material. In this embodiment the electrical connection material 18 through different openings in sheets 12, 14, 16, 17 contact the contact islands and the first surface outside the islands, an emitter or a back surface field lying adjacent the first surface when the first surface is a front surface field or an emitter respectively. In each embodiment, one or more layers of dielectric layer material may be present at the surface of substrate 10 and sheets 12, 14, 16, 17. Furthermore, conductor tracks may be present at the surface of substrate 10. Openings of a first and second type are provided through the sheets 12, 14, 16, 17.
Figure 3, 3a show a detailed cross-section of an opening of the first type, which comprises aligned openings in first electrically conductive
sheet 12, second electrically conductive sheet 14 and electrically isolating sheet 16. As shown in figure 3a, an electrically isolating sheet 12a may be provided between substrate 10 and first electrically conductive sheet 12, for example if substrate 10 has no layer of isolating material at locations where contact to first electrically conductive sheet 12 is undesirable. Electrically isolating sheet 12a may be an EVA, PVB, silicone sheet for example.
The opening in first electrically conductive sheet 12 has a first size. The opening in a combination of second electrically conductive sheet 14 and electrically isolating sheet 16 has a second size, larger than the first size, leaving first electrically conductive sheet 12 exposed through the latter opening along a perimeter of the opening in first electrically conductive sheet 12, i.e. along a rim of the opening. As shown, the exposed perimeter is present on both sides of the opening, for example everywhere along the edge at the entire perimeter of the opening. But alternatively, the perimeter may be exposed only along part of the opening, for example only on one side in the cross-section. When an opening extends along a line (only the cross- section of this line being shown in figures 3, 3a), the opening may leave first electrically conductive sheet 12 exposed through the latter opening along a rim on one or both sides of the line.
During manufacture connection material 18 may be applied through the openings. Subsequently, excess material above the openings may be removed, for example by means of a squeegee. Following removal of excess material the connection material 18 may be cured, for example in a heating step wherein the cell including the connection material 18 is heated. In the manufactured photo-voltaic cell, electrical connection material 18 is present in the openings, contacting an area at the surface of semi-conductor body 10 and the exposed part of first electrically conductive sheet 12 along the perimeter of the opening. First electrically conductive sheet 12 and electrical connection material 18 are in physical contact, as are surface of substrate 10 and electrical connection material 18 (electrical connection
material 18 may be contact with a part of substrate 10 that itself is not a semi-conductor, such as a conductor track).
As shown, further electrically isolating sheet 17 also has an opening aligned with the opening through the combination of the second electrically conductive sheet 14 and electrically isolating sheet 16, leaving first electrically conductive sheet 12 exposed through the latter opening along a perimeter of the opening in first electrically conductive sheet 12. Further electrically isolating sheet 17 functions to present electrical contact between electrical connection material 18 and second electrically conductive sheet 14. But further electrically isolating sheet 17 may be omitted if removal of excess material above the openings is done in a way that removes the material sufficiently to prevent undesired short circuits with areas outside the opening. In an embodiment electrically isolating sheet 16 and optionally further electrically isolating sheet 17 extend further into the opening than second electrically conductive sheet 14. This ehminates or reduces electrical contact between electrical connection material 18 and second electrically conductive sheet 14 in the openings of the type shown in figures 3, 3a. However, this may not be needed, since a very thin second electrically conductive sheet 14 may be used, having a lateral contact area exposed to the hole that provides at most a low conductance connection. Also it may not be needed if electrical connection material 18 is applied
selectively within a perimeter of the opening through second electrically conductive sheet 14. As shown in figures 3, 3a, a space may arise between electrically isolating sheet 16 further electrically isolating sheet 17 at locations between the electrical connection material 18 and second
electrically conductive sheet 14. When thermoplastic isolating material is used, this space may party or wholly be filled by material (not shown) from electrically isolating sheet 16 and/or further electrically isolating sheet 17, as a result of a heating step such as a heating step wherein electrical connection material 18 is cured.
Figure 4 shows a detailed cross-section of an opening of the second type, which also comprises aligned openings in first electrically conductive sheet 12, second electrically conductive sheet 14 and electrically isolating sheet 16. The opening in first electrically conductive sheet 12 has a third size. The opening in a combination of second electrically conductive sheet 14 and electrically isolating sheet 16 has a fourth size, larger than the third size, covering the perimeter of first electrically conductive sheet 12, and preferably extending into the opening beyond the perimeter of the opening in the first electrically conductive sheet 12. Further electrically isolating sheet 17, if present, also has an opening aligned with the opening through the combination of the second electrically conductive sheet 14 and electrically isolating sheet 16, but with a larger opening, leaving second electrically conductive sheet 14 exposed along a perimeter of the opening in second electrically conductive sheet 14. In an embodiment, second
electrically conductive sheet 14 may be exposed along the entire perimeter. But alternatively, it may be exposed only along part of the perimeter. When an opening extends along a line (only the cross-section of this line being shown in figure 4), the opening may leave second electrically conductive sheet 14 exposed through the latter opening along a rim on one or both sides of the line.
Not all openings need have the same shape, or if the openings have the same shape, the openings need not have the same orientation. For example, at least part of the openings may have an elongate shape, such as an elliptical shape or a substantially rectangular shape, which have a larger diameter in a primary direction than in a secondary direction. In this embodiment, the sheets may have differently oriented first and openings, e.g. with the primary direction of the first openings at a non-zero angle, such as a substantially perpendicular angle, to the primary direction of the second openings. This can be used to align the sheets in both these directions by bringing corresponding openings in overlapping positions.
In another embodiment, cross-shaped openings (e.g. + shaped) may be used in part of the sheets, and openings that contain only one leg of the cross (e.g. _ ) in one or more other sheets that are closer to substrate 10. An optical sensor may be used to determine the offset between the centre of the cross and the leg of the openings in the sheets with one leg as seen through the cross-shaped opening, and the resulting detection signal may be used to control a displacement mechanism to adjust the relative position of the sheets in a direction wherein the leg is moved towards the centre of the cross. Similar structures may be used to align the sheets with the substrate, using metal patterns on the substrate for example.
During manufacture connection material 18 may applied through the opening. Excess material may be removed and electrical connection material 18 may be cured in a heating step. In the manufactured photovoltaic cell, electrical connection material 18 is present in the opening, contacting an area at the surface of semi-conductor body 10 and the exposed part of second electrically conductive sheet 14 along the perimeter of the opening. Second electrically conductive sheet 14 and substrate 10 are in physical contact with electrical connection material 18. As shown in figure 4, when thermoplastic isolating material is used, a heating step may cause material from electrically isolating sheet 16 to deform into a space between first conductor sheet 12 and electrical connection material 18.
The photovoltaic cell may be manufactured by separately manufacturing substrate and a composite sheet comprising first electrically conductive sheet 12, electrically isolating sheet 16, second electrically conductive sheet 14, and optionally further electrically isolating sheet 17 attached to each other. First electrically conductive sheet 12 and second electrically conductive sheet 14 may be manufactured from electrically conductive foil, by creating a predefined pattern of openings through each foil as defined in a design of the photo-voltaic cell. The same pattern of openings is created in both foils, but with differently sized openings, the
openings of the first type being smaller in the foil of first electrically conductive sheet 12 than those in second electrically conductive sheet 14 and the openings of the second type being larger in the foil of first electrically conductive sheet 12 than those in second electrically conductive sheet 14. In an embodiment only openings of a first and second size may be created in the foil of first electrically conductive sheet 12, according to whether contact to the first or second electrically conductive sheet 12, 14 is designed. In this embodiment openings of a third and fourth size may be created in the foil of second electrically conductive sheet 14, at positions corresponding to those of the openings of the first and second size in the foil of first electrically conductive sheet 12 respectively, the third size being larger than the first size and the fourth size being smaller than the second size.
Openings may be created for example by punching openings from the foil, laser ablation, by etching using an etchant that is selectively applied at the location of the openings, for example by printing the etchant, or printing or photo-lithographically defining a mask layer and applying the etchant through the mask layer. Electrically isolating sheet 16 and optionally further electrically isolating sheet 17 may be similarly
manufactured from an electrically isolating foil. In an embodiment second electrically conductive sheet 14 and electrically isolating sheet 16 may be manufactured together from a foil comprising an electrically conductive layer covered by an electrically isolating layer, the openings through both layers being created together. Similarly, first electrically conductive sheet 12 may be manufactured together from a foil comprising an electrically conductive layer covered by an electrically isolating layer. This electrically isolating layer may form an electrically isolating sheet (not shown) between first electrically conductive sheet 12 and substrate 10.
In an embodiment, after creating the openings, the foils may be joined in a composite sheet with a stack of foils that successively comprises
the foils with openings for first electrically conductive sheet 12, electrically isolating sheet 16, second electrically conductive sheet 14, and optionally further electrically isolating sheet 17. The foils may be joined by means of adhesive for example. Optionally another electrically isolating foil may be included. Subsequently, the composite sheet may be applied to substrate 10, with first electrically conductive sheet 12 closest to substrate 10. The composite sheet may be connected to substrate 10 by adhesive for example. In an alternative embodiment, after creating the openings, the foils may be joined to the semi-conductor one after the other.
In a next step electrical connection material 18 is applied to the combination of composite sheet is applied to substrate 10, through the openings. Electrical connection material 18 may be a conductive ink, a paste containing metal grains, solder (e.g. SnBi solder which has a melting temperature of 138 degrees centigrade), tin and/or an electrically conductive adhesive for example. In an embodiment, low-temperature curing paste is used, which is known per se. A paste with a curing temperature of 150 degrees centigrade may be used. Such a paste may comprise grains of conductive material and a solvent or polymer matrix of a material that evaporates or hardens at the curing temperature. When a thermoplastic inner sheet 12a is used, curing of the paste and processing of the inner sheet 12a is preferably performed in a common processing step at a processing temperature at or above the curing temperature of the paste and at or above the temperature at which the thermoplastic inner layer 12a becomes plastic. In an embodiment wherein substrate 10 comprises a heterojunction, use of such a low temperature curing paste has the additional advantage that the heterojunction is not degraded at this temperature. The same goes for an embodiment wherein substrate 10 is provided on a glass carrier.
In an embodiment, electrical connection material 18 is applied over the entire surface of the composite sheet and followed by removal of electrical connection material 18 that extends above the uppermost layer of
the composite sheet, for example by means of a squeegee that forces the material into the openings and removes excess material in one action. If liquid solder material is used, the capillary effect may be sufficient to draw the solder material into the openings without forcing it into the openings. In another embodiment, electrical connection material 18 may be applied by printing a pattern of electrical connection material 18 selectively in the openings, e.g. by means of screen printing or by "inkjet" printing, involving launching droplets or particles of electrical connection material 18 at selected positions. Alternatively, other position dependent selective deposition methods may be used.
As will be clear from the preceding description, the use of a stack of sheets including electrically conductive sheets and at least one electrically isolating sheet, with aligned openings of different size makes it possible to create connections between areas on substrate 10 and different ones the of electrically conductive sheets in a single application step wherein electrical connection material 18 is applied. Although examples have been described wherein two electrically conductive sheets are used, it should be appreciated that a stack more than two electrically conductive sheets may be used, successively separated by electrically isolating sheets. Also in this case, different types of openings may be used in the stack, with aligned openings in the sheets, wherein the opening in one electrically conductive sheet is smaller than those in the other sheets, leaving a perimeter of the opening in the one electrically conductive sheet exposed, so that it will be connected to the semi-conductor body 10 when electrical connection material 18 is applied in the opening. In this case, different types of opening in the stack correspond to openings wherein different ones of the electrically conductive sheets have the smallest opening.
Although embodiments have been described wherein both electrically conductive sheets 12, 14 are provided over substrate 10 of a single photo-voltaic cell only, it should be appreciated that in an assembly of
such cells conductive sheets 12, 14 may extend over a plurality of such cells, connecting the cells. One electrically conductive sheet 12, 14 may connect the cell to a first other cell and the other electrically conductive sheet 12, 14 may connect the cell to a second cell, for example.
Although embodiments have been described wherein, except for the openings like in sheet 14, electrically conductive sheets 12, 14 extend continuously over the semi-conductor body 10 of an entire photo-voltaic cell or over the semi-conductor bodies 10 of an entire assembly of photo-voltaic cells, it should be appreciated that electrically conductive sheet 12, 14 may be interrupted. Thus for example electrically isolating sheet 16 and/or another electrically conductive sheet 12, 14 may run on where the
electrically conductive sheet 12, 14 is interrupted, separating the electrically conductive sheet 12, 14 into parts that are electrically isolated from one another. This makes it possible to realize more complex connection patterns.
Figures 5a-c show a connection between photo-voltaic cells.
Figure 5a shows a cross-section through a photo-voltaic cell with a substrate 56a. On an edge at a side of substrate 56a electrically isolating sheet 16, second electrically conductive sheet 14 and further electrically isolating sheet 17, if present, end short of first electrically conductive sheet 12, exposing a first strip 52 of first electrically conductive sheet 12. If further electrically isolating sheet 17 is present, further electrically isolating sheet 17 ends short of second electrically conductive sheet 14 along another edge at another side of substrate 56a, exposing a second strip 50 of second electrically conductive sheet 14. Figure 5b illustrates an embodiment wherein the first and second strip are on parallel edges of the cell, but alternatively they may be provided on edges that are at right angles to each other.
Figure 5b shows sides of first and second adjacent substrate 56a,b of cells of the type shown in figure 5a. The side of first substrate 56a at which its first strip is located is adjacent the side of second substrate 56b at
which its second strip is located. An electrical conductor 54 is provided in electrical contact with both strips, thereby connecting the cells in series. Fig 5c shows a top view corresponding to figure 5b.
Figure 6 shows an array with rows and columns of photo-voltaic cells. In this the photo-voltaic cells are interconnected as shown in figure 5a- c, using first and second strips 50, 52. Part of the cells has strip at parallel edges on opposite sides of the photo-voltaic cells. Other photo-voltaic cells, located along opposite edges of the array, have first and second strips 50, 52 along adjacent edges at right angles to each other (except where the strips meet). In this way series connections between cells in different columns of the array are realized. Although a pattern of connections is shown in which cells in each column are connected in series and the connections between the columns are made at the ends of the columns, alternatingly at opposite sides of the array, it should be understood that connections along any other path through a series of the cells may be used.
Figure 7a shows an array of substrates of photo-voltaic cells with beveled corners, e.g. corners cut short with an oblique edge or rounded corners. Such substrates are also known as semi-square substrates. When used in an array of substrates, the space left between the beveling of adjacent substrates leaves space for connections between conductor sheets of adjacent cells.
Figure 7b shows examples of first and second conductor sheets 70, 72 for use on a beveled substrate (for the sake of illustration the sheets are shown at a slight offset to each other, but preferably their edges overlay at the unbeveled part of the edges of the substrate). Neither the insulating layer between the sheets nor the holes for connections through the sheets are explicitly shown.
First conductor sheet 70 has "ears" that extend beyond the substrate beyond its beveling at a first and second adjacent corner of the substrate. Thus, in the array the ears reach into the space between the
substrate and a first adjacent substrate, left by the beveling. Second conductor sheet 72 has similar "ears" extending beyond the beveling of the substrate at a third and fourth corner of the substrate. Thus in the array the ears of the second conductor sheet reach into the space between the substrate and a second adjacent substrate on a side of the substrate opposite to that adjacent the first adjacent substrate. Thus, the ears of first conductor sheet 70 of the cell may be electrically joined to the ears of the second conductor sheet of the first adjacent cell and the ears of second conductor sheet 72 of the cell may be electrically joined to the ears of the first conductor sheet of the second adjacent cell. Although a specific shape of the ears is shown by way of illustration, it should be appreciated that other shapes may be used: the ears need not reach through the entire space between the substrates as long as there is overlap that allows for joining with ears from adjacent cells.
A photo-voltaic cell of a first type comprises the substrate, the conductor sheets with ears as shown and an electrically insulating layer between the conductor sheets. Any type of connections from the sheets to the substrate as described may be used. Cells with the sheets of figure 7b may be used in the array where successive cells in a column or row are connected in series. Photo-voltaic cell of other types may have different configurations of ears to provide for different coupling patterns. For example for cells to be used where the connection pattern makes a turn e.g. at a corner of the array, ears may be provided on diagonally opposite corners of the substrate.
Figure 7c shows examples of first and second conductor sheets 70,
72 for use together in a second type of photo-voltaic cell with a beveled substrate. Herein first conductor sheet 70 is similar to that of figure 7b, with ears at adjacent first and second corners of the substrate. Second conductor sheet 70 has a single ear at a third corner of the substrate, direct in a direction perpendicular to that of the ears of first conductor sheet 70.
Claims
1. A method of manufacturing a photo-voltaic cell, the method comprising
- providing first and second openings in a first electrically conductive sheet;
- providing third and fourth openings in a combination of a second
electrically conductive sheet and an electrically isolating sheet,
- providing a stack of sheets on a substrate, the substrate comprising a semi-conductor body of the photovoltaic cell, the stack comprising the first and second electrically conductive sheet and the electrically isolating sheet, the first electrically conductive sheet lying between the electrically isolating sheet and the substrate, the electrically isolating sheet lying between the second electrically conductive sheet and the first electrically conductive sheet;
wherein the third and fourth openings are aligned with the first and second openings respectively in the stack, and the third openings have a shape that exposes the first electrically conductive sheet along a perimeter of the first openings that are aligned with the third openings, and the fourth openings having a shape that covers a perimeter of the second openings that are aligned with the fourth openings;
- applying electrical connection material through the first and third openings to connect the substrate to the first electrically conductive sheet, and through the second and fourth openings to connect the substrate to the second electrically conductive sheet.
2. A method according to claim 1, wherein the stack comprises a further electrically isolating sheet, the second electrically conductive sheet lying between the electrically isolating sheet and the further electrically isolating sheet, the further electrically isolating sheet having further openings, aligned with the third and fourth openings, the further openings
having a shape that leaves the second electrically conductive sheet exposed along a perimeter of the fourth openings, the further electrically isolating sheet covering the second electrically conductive sheet at least up to the perimeter of the third openings.
3. A method according to claim 2, wherein the electrical connection material is applied on the further electrically isolating sheet and in the further openings and swept off the further electrically isolating sheet outside the further openings.
4. A method according to claim 1 or 2, wherein the electrical connection material is printed in islands located in the third and fourth openings, the islands in the third openings extending over the first electrically conductive sheet along a perimeter of the first openings, the islands in the fourth openings extending over the second electrically conductive sheet along a perimeter of the fourth openings.
5. A method according to any one of the preceding claims, wherein the electrical connection material is a solder with a melting temperature at or below a hundred and fifty degrees centigrade or a thermally curable material with a curing temperature at or below that temperature, the applying electrical connection material step comprising heating the electrical connection material to or above the melting temperature or the curing temperature.
6. A method according to any one of the preceding claims, wherein the electrically isolating sheet and the second electrically conductive sheet end short of the first electrically conductive sheet along an edge at a side of the substrate, exposing a first strip of the first electrically conductive sheet.
7. A method according to claim 2, wherein the electrically isolating sheet, the second electrically conductive sheet and the further electrically isolating sheet end short of the first electrically conductive sheet along an edge at a first side of the substrate, exposing a first strip of the first electrically conductive sheet and the further electrically isolating sheet ends
short of the second electrically conductive sheet along an edge at a second side of the substrate.
8. A method according to any one of the preceding claims, comprising
- assembling the stack comprising the first and second electrically conductive sheet separated by the electrically isolating sheet, aligned with each other
- placing the stack on the substrate.
9. A method according to any one of the preceding claims, wherein the electrical connection material is a conductive adhesive.
10. A method according to any one of the preceding claims, wherein the stack comprises an inner electrically isolating sheet, lying between the first electrically conductive sheet and the substrate, the inner electrically isolating sheet having further openings, aligned with the first and second openings.
11. A method according to claim 10, wherein the inner electrically isolating sheet is a thermoplastic polymer sheet and the thermoplastic polymer sheet is heated to a temperature where it is plastic when it is on the substrate, or provided at that temperature when it is applied to the substrate.
12. A method according to claim 11, wherein the electrical connection material is a solder or a thermally curable material, the solder or thermally curable material being applied in molten form or cured when the
thermoplastic polymer sheet is plastic due to its temperature or made plastic by heating in a single processing step.
13. A photo-voltaic cell, comprising
- a substrate that comprises a semi-conductor body of the photovoltaic cell
- a first electrically conductive sheet on the substrate, with first and second openings in the first electrically conductive sheet;
- an electrically isolating sheet on the first electrically conductive sheet; - a second electrically conductive sheet on the electrically isolating sheet;
- third and fourth openings in a combination of the second electrically conductive sheet and the electrically isolating sheet, the third and fourth openings being aligned with the first and second openings respectively, wherein the third openings have a shape that exposes the first electrically conductive sheet along a perimeter of the first openings aligned with the third openings, and the fourth openings having a shape that covers a perimeter of the second openings aligned with the fourth openings;
- electrical connection material through the first and third openings, electrically connecting the substrate to the first electrically conductive sheet, and through the second and fourth openings electrically connecting the substrate to the second electrically conductive sheet.
14. A photo-voltaic cell according to claim 13, comprising a further electrically isolating sheet on the second electrically conductive sheet, the further electrically isolating sheet having further openings, aligned with the third and fourth openings, the further openings leaving the second electrically conductive sheet exposed along a perimeter of the fourth openings, the further electrically isolating sheet covering the second electrically conductive sheet at least up to the perimeter of the third openings.
15. A photo-voltaic cell according to claim 13 or 14, wherein the electrically isolating sheet and the second electrically conductive sheet end short of the first electrically conductive sheet along an edge at a side of the substrate, exposing a first strip of the first electrically conductive sheet.
16. A photo-voltaic cell according to claim 14, wherein the electrically isolating sheet, the second electrically conductive sheet and the further electrically isolating sheet end short of the first electrically conductive sheet along an edge at a first side of the substrate, exposing a first strip of the first electrically conductive sheet and the further electrically isolating sheet ends short of the second electrically conductive sheet along an edge at a second side of the substrate.
17. A photo-voltaic cell according to claim 16, wherein the first and second edge are parallel to each other.
18. A photo-voltaic cell according to claim 17, wherein the first and second edge are adjacent edges of the substrate.
19. An assembly of photovoltaic cells, comprising a first photo-voltaic cell according to the any one of the claims 15- 18, and wherein the first photo-voltaic cell is electrically connected to a second photovoltaic cell via said first strip.
20. An assembly of photovoltaic cells, comprising a first photo-voltaic cell according to any one of claims 16- 18, wherein the first photo-voltaic cell is electrically connected to a second and third photovoltaic cell via said first and second strip.
21. A photo-voltaic cell according to any one of claims 13-20, wherein the fourth openings comprise aligned sub-openings in the second electrically conductive sheet and the electrically isolating sheet, the sub-openings in the second electrically conductive sheet extending to an edge of the fourth openings and the sub-openings in the electrically isolating sheet having an edge spaced from the edge of the fourth openings.
22. A photo-voltaic cell to any one of claims 13-21, wherein the third openings comprise aligned sub-openings in the second electrically
conductive sheet and the electrically isolating sheet, the sub-openings in the electrically isolating sheet extending to an edge of the third openings, the sub-openings in the second electrically conductive sheet having an edge spaced from the edge of the fourth openings.
23. A photo-voltaic cell to any one of claims 13-21, wherein the stack comprises an inner electrically isolating sheet, lying between the first electrically conductive sheet and the substrate, the inner electrically isolating sheet having further openings, aligned with the first and second openings.
24. A photo-voltaic cell to claim 23, wherein the inner electrically isolating sheet is a thermoplastic polymer sheet.
25. A photo-voltaic cell to any of claims 13-24, wherein the substrate has beveled corners, the first and second electrically conductive sheet having parts extending beyond the substrate at a first and second one of the beveled corners respectively.
26. An assembly of photo-voltaic cells comprising an array of photovoltaic cells, the array comprising a first and second photo-voltaic cell according to claim 25, wherein the extending part of the first electrically conductive sheet of the first photo-voltaic cell overlaps and is electrically connected to the extending part of the second electrically conductive sheet of the second photo-voltaic cell.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL2011230 | 2013-07-26 | ||
| NL2011230A NL2011230C2 (en) | 2013-07-26 | 2013-07-26 | Photo-voltaic cell its manufacture and an assembly of such photo-voltaic cells. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2015012697A1 true WO2015012697A1 (en) | 2015-01-29 |
Family
ID=49261716
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/NL2014/050515 WO2015012697A1 (en) | 2013-07-26 | 2014-07-25 | Photo-voltaic cell its manufacture and an assembly of such photo-voltaic cells |
Country Status (3)
| Country | Link |
|---|---|
| NL (1) | NL2011230C2 (en) |
| TW (1) | TW201513374A (en) |
| WO (1) | WO2015012697A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20220060145A1 (en) * | 2020-08-21 | 2022-02-24 | The Boeing Company | Flexible circuit for solar cell assemblies |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102008044910A1 (en) * | 2008-08-30 | 2010-03-04 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Solar cell and solar cell module with one-sided interconnection |
| WO2012015307A1 (en) * | 2010-07-30 | 2012-02-02 | Stichting Energieonderzoek Centrum Nederland | Solar cell module and method for manufacturing such a module |
| US20120240995A1 (en) * | 2011-03-25 | 2012-09-27 | Kevin Michael Coakley | Foil-based interconnect for rear-contact solar cells |
-
2013
- 2013-07-26 NL NL2011230A patent/NL2011230C2/en not_active IP Right Cessation
-
2014
- 2014-07-25 TW TW103125536A patent/TW201513374A/en unknown
- 2014-07-25 WO PCT/NL2014/050515 patent/WO2015012697A1/en active Application Filing
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102008044910A1 (en) * | 2008-08-30 | 2010-03-04 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Solar cell and solar cell module with one-sided interconnection |
| WO2012015307A1 (en) * | 2010-07-30 | 2012-02-02 | Stichting Energieonderzoek Centrum Nederland | Solar cell module and method for manufacturing such a module |
| US20120240995A1 (en) * | 2011-03-25 | 2012-09-27 | Kevin Michael Coakley | Foil-based interconnect for rear-contact solar cells |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20220060145A1 (en) * | 2020-08-21 | 2022-02-24 | The Boeing Company | Flexible circuit for solar cell assemblies |
| US11722094B2 (en) * | 2020-08-21 | 2023-08-08 | The Boeing Company | Flexible circuit for solar cell assemblies |
Also Published As
| Publication number | Publication date |
|---|---|
| NL2011230C2 (en) | 2015-01-27 |
| TW201513374A (en) | 2015-04-01 |
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