TW201513374A - Photo-voltaic cell its manufacture and an assembly of such photovoltaic cells - Google Patents

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

Photovoltaic cell manufacturing method and photovoltaic cell assembly Field of invention

The present invention relates to photovoltaic cells and photovoltaic cells, and to methods of making one of the cells.

Background of the invention

The photovoltaic cell produces an output voltage between the base and emitter regions on the surface of the body of the semiconductor material. To utilize this voltage and associated current, an external electrical conductor is used in a battery assembly from a connection of the base and emitter regions to other cells or to the output terminals of the battery (as in this context) As used, an "external" conductance system is a paste or other material that is not formed prior to application to the semiconductor body, i.e., during or after application to the semiconductor body. In a "back contact" photovoltaic cell, the first and second external conductance systems are coupled to the back surface of the semiconductor body or to a conductive material that has been deposited on the body. Hereinafter, the semiconductor body, or conductive material that has been deposited on the body, will collectively be considered the substrate or body.

PCT/NL2011/050547 and DE102008044910A1 describe photovoltaic cells in which a conductive foil is used as the first and second electrical conductors. When connected to the substrate at a plurality of points, the use of continuous sheets instead of meshed conductor lines reduces complexity and improves conductivity. What is needed, however, is that the outermost sheet is attached to the substrate by an opening in the innermost sheet, and the possible selection between the sheets outside the openings and between the sheets and the substrate Electrical isolation is provided at the location.

The sheets can be attached to the substrate using different alternating methods. In an alternative method, a bonding material such as a conductive adhesive or solder is first applied to the sheets and/or the substrate and the sheets are attached to the substrate using the joining material. The conductive sheets and a separator sheet interposed between the conductive sheets may be applied one after the other or as a composite sheet comprising two or more individual sheets attached to each other.

A problem with these alternative methods is that the height of the joining material is critical, in particular for attachment to the outermost sheet by an opening in the innermost sheet. When the sheets are applied to the substrate, the joining material can be dispersed. This will be accompanied by the risk of shorting between the sheets, which increases as the height of the joining material increases. Moreover, since the outer sheet is closed, it is more difficult to position the openings of the first sheet on the contacts of the battery. Once attached, the sheet is difficult to repair faulty contacts, such as open-circuit contacts. This risk can limit the minimum size of the openings that can be used and the number of openings. On the other hand, when the height of the connecting material in the openings is smaller than the thickness of the innermost sheet and the spacer, an open circuit may occur between the outermost sheet and the substrate.

Summary of invention

Among other things, it is an object of the present invention to provide a means of applying a joining material to connect an outer conductor layer to the semiconductor body of the photovoltaic cell, reducing the risk of open circuit and/or short circuit.

A method as claimed in claim 1 is provided. This method considers the application of the electrical connection material in one step to form a two-type connection to the semiconductor body. In one embodiment, a stack of sheets comprising at least two electrically conductive sheets having one or more electrically isolating sheets between the electrically conductive sheets is used. The openings provided pass through the stack, and each opening through the stack includes alignment openings in the conductive sheets and one or more electrically isolating sheets.

Different types of openings through the stack are used for making electrical contacts to different conductive sheets in the stack. In the opening through which the stack is used to contact a conductive sheet in a stack, the opening in the conductive sheet has a smaller opening in the conductive sheet, if any, above the stack The dimensions are such that the conductive sheet is exposed along the perimeter of at least a portion of the opening of the period (as used herein, "above" means a greater distance from the semiconductor body). Different types of openings through the stack are used, wherein different conductive sheets have smaller sized openings.

In a photovoltaic cell, the stack is positioned on a substrate comprising the semiconductor body of the photovoltaic cell. The different types of openings may be disposed on the substrate for differently contacting the substrate and the emitter of the substrate, either directly or directly via the base and/or emitter contact electrodes of the substrate. Area. The first type of opening can be covered to contact the base The region and the opening of the second version may be positioned to cover the area for contacting the emitter or vice versa. The electrical connection material may be in direct or indirect electrical contact with the base and emitter in the openings.

The stack is provided on a substrate of the semiconductor body comprising the photovoltaic cell. That is, the sheets, including the openings, are present prior to being placed on the substrate. It is therefore possible to make these openings using simple techniques. The stack may be provided by continuously placing the sheets on the substrate, or by pre-stacking (e.g., laminating) the sheets and placing the pre-stacked sheets together on the substrate as A stack. The sheets may be flexible materials such that their cross-sectional shape, as seen by the cross-section of the substrate and the sheets, is determined solely by the substrate.

The electrical connection material can be applied in a single step to all openings through the stack on the substrate. In one embodiment, the electrical connection material comprises metal particles in a paste or liquid substrate. The use of different types of openings enables the application of the same electrical connection material to connect different regions of the substrate to different conductive sheets. The substrate can include a region of conductive material on the semiconductor body that is a portion of the connections to the semiconductor body that provide coverage through the openings of the stack.

In a specific embodiment, a further electrically isolating sheet is placed on the outermost conductive sheet, having an alignment opening in which the outermost conductive sheet does not have a minimum dimension in the type of opening. Arriving at the edge of the opening of the outermost conductive sheet. This prevents accidental contact between the electrical connection material and the outermost conductive foil.

In one embodiment, an electrical connection material is applied over the further electrically isolating sheet and the further holes and the further electrically isolating sheet outside the further holes is removed.

In one embodiment, the electrical connection material is printed in an island portion seated in the openings, extending to cover the exposed surrounding portion. This enables the use of minimal electrical connection materials and reduces accidental short circuits.

10‧‧‧Substrate

12,14,16,17‧‧‧Sheet

12a‧‧‧Electrical isolation sheet

18‧‧‧Electrical connection materials

50‧‧‧Article 2

52‧‧‧Article 1

54‧‧‧Electrical conductor

56a, 56b‧‧‧ substrate

70‧‧‧First conductor sheet

72‧‧‧Second conductor sheet

These and other objects and advantages will be apparent from the description of the exemplary embodiments.

1, 1a show a cross section through a photovoltaic cell; Fig. 2 shows a plan view of the photovoltaic cell; Figs. 3, 3a show a cross section through a first type of opening; Fig. 4 shows a second type through Cross section of the opening; Figures 5a-c show a connection between photovoltaic cells; Figure 6 shows an array of photovoltaic cells; Figure 7a shows an array of photovoltaic cells; Figure 7b, c shows conductor slices for cells in an array .

Detailed description of the preferred embodiment

1, 1a shows a cross section through a photovoltaic cell, comprising a substrate 10 comprising a semiconductor body optionally with a metallization and coating, and a plurality of sheets 12, 14, 16, 17 and electrical connection materials 18 (shown only as part of the battery and the ratio of horizontal to vertical is not drawn to scale). The sheets may be foil layers that are not integrally formed with the substrate 10, so that they can It is sufficient to make a pre-formed sheet before being placed on the substrate. The sheets include at least one first conductive sheet 12, a second conductive sheet 14, an electrically isolating sheet 16, and a further electrically isolating sheet 17. For the sake of clarity, the sheets 12, 14, 16, 17 are illustrated as being spaced apart from one another and at a distance from the substrate 10, although it will be appreciated that the sheets are in contact with one another. The second conductive sheet 14, the electrically isolating sheet 16, and the first conductive sheet 12 are continuously disposed between the further electrically isolating sheet 16 and the substrate 10. The electrical connection material 18 in contact with the upper region of the substrate 10 presents an alignment opening through the first conductive foil 12, the electrically isolating foil 16, the second electrically conductive foil 14, and the further electrically isolating foil 17. By way of example, only the two openings with the electrical connection material 18 are shown, but it will be appreciated that more openings may be present.

Figure 1a shows a specific embodiment in which an inner electrically isolating sheet 12a is provided between the first electrically conductive sheet 12 and the substrate 10. The inner electrically isolating sheet 12a can be a thermoplastic polymer sheet. Ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), decane, ionic polymer or thermoplastic urethane (TPU) flakes can be used, as is known as a non-trapping air-attached substrate 10 . If the substrate 10 contains an exposed region at a location in contact with the first conductive sheet 12, the inner electrically isolating sheet 12a can be used to prevent the contact.

2 shows a plan view of the photovoltaic cell including further electrically isolating sheets 17 and regions of electrical connection material 18 therethrough. A further electrically isolating sheet 17 is the outermost sheet. For a back-junction point-contact cell, for example, a density in the range of 0.1 to 30 openings/square inch can be used. For metal wrap through cell, emitter through battery (emitter Wrap through cell and an interdigitated back contact cell having multiple contacts may use a density in the range of 0.4 to 50 openings per square inch. By way of example, a rectangular array of openings having regions of circular electrical connection material 18 is shown, although it will be appreciated that any pattern may be used and that regions of the electrical connection material 18 may have different shapes: they may follow a line , for example, extending in a straight line.

As usual, for example, a solar cell, the substrate 10 can each comprise a first conductivity type (eg, n-type) doped semiconductor material (eg, germanium) having a region of a different doped semiconductor material at its surface, It may constitute an emitter or surface field region, enhance doping of the first conductivity pattern or doping a relative conductivity (eg, p-type). The layers can be completed by adding doping to the semiconductor material or adding a layer to the semiconductor.

The substrate 10 may have an emitter and a surface field region at its surface on the side having the sheets 12, 14, 16, 17, which are in contact with different emitter and surface field regions. Opening. In another embodiment, an emitter layer and a surface layer may be located on the mutually opposing surface first surface and the second surface of the substrate 10, using a through hole from the second surface to the first surface. The island portions of the joint at the first surface are isolated, and the through holes may be filled with a conductor material. In this embodiment, the electrical connection material 18 passing through different openings in the sheets 12, 14, 16, 17 contacts the contact island portions and the first surface outside the island portions, When the first surface system is a front surface field or an emitter, respectively, an emitter or a back surface field is adjacent to the first surface. In each embodiment, there may be one at the surface of the substrate 10 and the sheets 12, 14, 16, 17. Or more layers of dielectric layer material. Furthermore, there may be conductor tracks at the surface of the substrate 10. Openings of the first and second types are provided through the sheets 12, 14, 16, 17.

3, 3a shows a detailed cross-section of one of the openings of the first version, including alignment openings in the first conductive sheet 12, the second conductive sheet 14, and the electrically isolating sheet 16. As shown in FIG. 3a, for example, if it is intended to have an insulating material layer at a position where the substrate 10 is in contact with the first conductive sheet 12, an electrically isolating sheet 12a is provided between the substrate 10 and the first conductive sheet 12. The electrically isolating sheet 12a can be, for example, an EVA, PVB, or decane sheet.

The opening in the first conductive sheet 12 has a first size. The opening of one of the second conductive sheet 14 and the electrically isolating sheet 16 has a second dimension larger than the first dimension, such that the first conductive sheet 12 passes around the opening in the first conductive sheet 12 The latter opening is exposed, that is, along one of the edges of the opening. As shown, the exposed perimeter is on either side of the opening, for example along the entire edge of the opening. Alternatively, however, the circumference may be partially exposed only along one of the openings, for example only on one side of the cross section. When an opening extends along a line (only the cross section of the line is shown in Figures 3, 3a), the opening allows the first conductive sheet 12 to pass the edge along one or both sides of the line Exposed to expose.

The joining material 18 can be applied through the openings during manufacture. Thereafter, excess material above the openings can be removed, such as by a squeegee. After removing excess material, the joining material 18 can be cured, for example in a heating step, wherein the battery comprising the joining material 18 is heated. to In fabricating photovoltaic cells, there is an electrical connection material 18 in the openings along which a portion of the surface of the semiconductor body 10 and an exposed portion of the first electrically conductive sheet 12 are contacted. The first conductive sheet 12 and the electrical connection material 18 are in physical contact, just like the surface of the substrate 10 and the electrical connection material 18 (the electrical connection material 18 can be in contact with a portion of the substrate 10 that is not itself a semiconductor, such as a semiconductor track).

As shown, the further electrically isolating sheet 17 also has an opening aligned with the opening through the combination of the second electrically conductive sheet and the electrically isolating foil 16 such that the first electrically conductive sheet 12 is along the first electrically conductive sheet 12 The periphery of the opening is exposed through the latter opening. The further electrically isolating foil 17 functions to present electrical contact between the electrical connection material 18 and the second electrically conductive foil 14. However, further electrical isolation sheets 17 may be omitted if the removal of excess material over the openings is accomplished in a manner sufficient to prevent undesired shorting of the material from the area outside the opening. In one embodiment, the electrically isolating sheet 16 and optionally further electrically isolating sheet 17 extend further into the opening than the second electrically conductive sheet 14. The electrical contact between the electrical connection material 18 and the second electrically conductive foil 14 in the opening of the version shown in Figures 3, 3a is thus eliminated or reduced. However, this is not necessary because an extremely thin second conductive sheet 14 can be used with a lateral contact area exposed to the aperture providing at most a low conductivity connection. At the same time, it may not be necessary if the electrical connection material 18 is selectively applied around one of the openings through the second conductive sheet 14. As shown in Figures 3, 3a, a space can be created between the electrically isolating sheet 16 and the further electrically isolating sheet 17 at a location between the electrically connecting material 18 and the second electrically conductive sheet 14. When using thermoplastic In the case of a spacer material, this space may be partially or entirely filled with a material (not shown) from the electrically isolating foil 16 and/or further electrically isolating foil 17, resulting from a heating step such as in which the electrical connection material 18 is cured. A heating step.

4 shows a detailed cross section of one of the openings of the second version, which includes alignment openings in the first conductive sheet 12, the second conductive sheet 14, and the electrically isolating sheet 16. The opening in the first conductive sheet 12 has a third size. In a combination of the second conductive sheet 14 and the electrically isolating sheet 16, the opening has a fourth dimension larger than the third dimension, covering the periphery of the first conductive sheet 12, and preferably extending into the opening beyond the first The periphery of the opening in a conductive sheet 12. Further electrically isolating sheet 17, if any, also has an opening aligned with the opening through the junction of the second conductive sheet 14 and the electrically isolating sheet 16, but having a larger opening for the first Two conductive sheets 14 are exposed along one of the openings in the second conductive sheet 14 along the position. In one embodiment, the second electrically conductive sheet 14 can be exposed along the entire perimeter. Alternatively, however, it may only be exposed along the periphery of the portion. When an opening extends along a line (only the cross section of the line is shown in FIG. 4), the opening allows the second conductive sheet 14 to pass through the latter along an edge on one or both sides of the line Exposure to the opening.

Not all openings need to have the same shape, or if the openings have the same shape, the openings need not have the same orientation. For example, at least a portion of the openings may have an elongated shape, such as an elliptical shape or an intrinsically rectangular shape having a larger diameter in the primary direction than the secondary direction. In this particular embodiment, the sheets may have first openings of different orientations, such as the primary orientation of the first openings being A non-zero angle, such as an angle substantially perpendicular to the primary direction of the second openings. This can be used to align the sheets in the two directions by placing the corresponding openings in partially overlapping positions.

In another embodiment, a cross-shaped opening (eg, a + shape) may be used in a portion of the sheet, and a foot that includes only a cross in one or more other sheets closer to the substrate 10 (eg, - shape). An optical sensor can be used to determine the offset between the center of the cross of the openings in the sheet having a foot visible through the cross-shaped opening and the foot, and the resulting detection signal can be used to control a displacement The mechanism adjusts the relative position of the sheets in a direction in which the foot moves toward the center of the cross. Similar structures can be used, for example, a metal pattern on the substrate to align the sheets with the substrate.

The joining material 18 can be applied through the opening during manufacture. Excess material can be removed and the joining material 18 can be cured in a heating step. In the fabricated photovoltaic cell, there is an electrical connection material 18 in the opening that contacts a region at the surface of the semiconductor body 10 and the exposed portion of the second conductive sheet 14 along the periphery of the opening. The second conductive sheet 14 and the substrate 10 are in physical contact with the electrical connection material 18. As shown in FIG. 4, when a thermoplastic release material is used, a heating step can cause the material to be deformed from the electrically isolating sheet 16 into a space between the first electrically conductive sheet 12 and the electrically connecting material 18.

The photovoltaic cell can be fabricated by separately manufacturing a substrate and a composite sheet comprising the first conductive sheet 12, the electrically isolating sheet 16, the second conductive sheet 14, and the further electrically isolating sheet 17, which are attached to each other. As in one As defined in the design of the photovoltaic cell, the first conductive sheet 12 and the second conductive sheet 14 may be made of a conductive foil by creating a predetermined pattern through one of the openings of each foil. The same pattern of openings is created in the two foils, but the openings are of different sizes. The openings of the first pattern in the foil of the first conductive sheet 12 are smaller than the openings in the second conductive sheet 14, and are in the first conductive The second type of opening in the foil of the sheet 12 is greater than the openings in the second conductive sheet 14. In one embodiment, only the openings of the first and second dimensions are produced in the foil of the first conductive foil 12, regardless of whether it is in contact with the first or second conductive sheets 12, 14. In this embodiment, only the openings of the third and fourth sizes may be generated in the foil of the second conductive sheet 14, respectively, in the first and second of the foil with the first conductive sheet 12. At the locations corresponding to the openings of the dimensions, the third dimension is greater than the first dimension and the fourth dimension is less than the second dimension.

For example, by laser stamping openings from the foil, laser ablation can be selectively applied at the locations of the openings by using an etchant, such as by printing the etchant, or by printing or photolithography. A mask layer is defined and the etchant is applied throughout the mask layer for etching operations to create openings. The electrically isolating foil 16 and optionally further electrically isolating foil 17 can likewise be fabricated from an electrically isolating foil. In one embodiment, the second electrically conductive sheet 14 and the electrically isolating foil 16 can be fabricated together from a foil comprising a conductive layer covered by an electrically isolating layer, together creating the openings through the two layers. Likewise, the first conductive sheets 12 can be fabricated together from a foil comprising a conductive layer covered by an electrically isolating layer. The electrically isolating layer can form an electrically isolating sheet (not shown) between the first electrically conductive sheet 12 and the substrate 10.

In a specific embodiment, after the openings are formed, the foils may be bonded to a composite sheet by a stack of foils, the stack of foils continuously comprising a first conductive sheet 12, an electrically isolating sheet 16, and a first The two conductive sheets 14 and optionally the openings of the openings for the electrically isolating sheets 17 are used. The foils, for example, may be bonded by an adhesive. Optionally, another electrically isolating foil can be included. Successively, the composite sheet can be applied to the substrate 10 with the first conductive sheet 12 closest to the substrate 10. For example, the synthetic sheet can be attached to the substrate 10 by an adhesive. In an alternate embodiment, the foils may be bonded to the semiconductor one after the other after the openings are created.

In the next step, the bonded electrical connection material 18 applied to the composite sheet is applied to the substrate 10 through the openings. For example, the electrical connection material 18 can be a conductive ink, a paste comprising metal particles, solder (eg, SnBi solder having a melting temperature of 138 degrees Celsius), tin and/or a conductive adhesive. In a specific embodiment, the use of a low temperature curing paste is known per se. A paste having a curing temperature of 150 ° C can be used. The paste may comprise particles of a conductive material and a solvent or a polymeric substrate of a material that evaporates or hardens at the curing temperature. When a thermoplastic inner sheet 12a is used, the curing of the paste and the processing of the inner sheet 12a are preferably at or above the curing temperature of the paste, and at or above the thermoplastic inner layer 12a. A common processing step is performed at a processing temperature at which the temperature at which the plastic is placed. In one embodiment, wherein substrate 10 comprises a heterojunction, the use of the low temperature curing paste has the added advantage that the heterojunction does not degrade at this temperature. One of them in one A particular embodiment of the substrate 10 provided on the glass carrier has the same advantages.

In one embodiment, an electrical connection material 18 is applied over the entire surface of the composite sheet, and then the electrical connection material 18 extending over the uppermost layer of the composite sheet, such as by a squeegee, forces the material into the openings. And remove and remove too much material in one action. If liquid solder is used, the capillary effect is sufficient to draw solder into the openings without forcing solder into the openings. In another embodiment, a pattern of electrical connection material 18 can be printed by selectively in the openings, such as by screen printing or by "inkjet" printing, at selected locations. Electrical connection material 18 is applied by placing droplets or particles of electrical connection material 18. Alternatively, other position dependent selective deposition methods can be used.

As will be apparent from the foregoing description, a stack of sheets comprising a conductive sheet and at least one electrically isolating sheet, having a different size of alignment opening enabling a single application step in which the electrical connection material 18 is applied, The regions on the substrate 10 create connections with different conductive sheets. Although an example in which two conductive sheets are used has been described, it should be appreciated that a stack of more than two conductive sheets can be used, continuously separated by electrically isolating sheets. Also in this example, different types of openings may be used in the stack, with aligned openings in the sheets, wherein the openings in a conductive sheet are smaller than the openings in the other sheets, giving way One of the openings is exposed in the one of the conductive sheets, so that when the electrical connection material 18 is applied in the opening, it will be connected to the semiconductor body 10. In this example, the different types of openings in the stack correspond to the openings of the different types of conductive sheets having the smallest opening.

Although the specific embodiment has been described in which the two conductive sheets 12, 14 are provided to cover only a single photovoltaic cell substrate 10, it should be appreciated that the conductive sheets 12, 14 may extend over a plurality of the one of the batteries. Wait for the battery and connect the batteries. For example, a conductive sheet 12, 14 can connect the battery to a first other battery, and additional conductive sheets 12, 14 can connect the battery to a second battery.

In the specific embodiment that has been described, in addition to the openings being in the sheet 14, the conductive sheets 12, 14 continuously extend over the semiconductor body 10 of an entire photovoltaic cell or the semiconductors that encompass the entire assembly of one of the photovoltaic cells. Body 10, but it should be appreciated that conductive sheets 12, 14 can be interrupted. For example, the electrically isolating sheet 16 and/or the other electrically conductive sheets 12, 14 can thus be placed at the break of the electrically conductive sheets 12, 14 which are separated into portions that are electrically isolated from one another. This enables a more complicated connection pattern to be realized.

Figures 5a-c show a connection between photovoltaic cells. Figure 5a shows a cross section through a photovoltaic cell having a substrate 56a. The electrically isolating sheet 16, the second electrically conductive sheet 14, and the further electrically isolating sheet 17, if any, are located on an edge of one of the sides of the substrate 56a, the ends being shorter than the first electrically conductive sheet 12, exposing the first One of the first strips 52 of conductive foil 12. If there is a further electrically isolating sheet 17, the end of the further electrically isolating sheet 17 along the other edge at the other side of the substrate 56a is shorter than the second conductive sheet 14, exposing one of the second conductive sheets 14 Article 50. Figure 5b illustrates an embodiment wherein the first and second strips are on two parallel edges of the cell, but alternatively they may be provided on edges that are at right angles to each other.

Figure 5b shows the sides of the first and second adjacent substrates 56a, b of the type of battery shown in Figure 5a. The side of the first substrate 56a at which the first strip is located is adjacent to the side of the second substrate 56b where the second strip is located. An electrical conductor 54 is provided in electrical contact with the two to connect the batteries in series. Figure 5c shows a top view corresponding to Figure 5b.

Figure 6 shows an array of photovoltaic cells with rows and columns. In this figure, the photovoltaic cells are interconnected using first and second strips 50, 52 as shown in Figures 5a-c. Portions of the cells have strips at parallel edges on opposite sides of the photovoltaic cells. Other photovoltaic cells positioned along opposite edges of the array have first and second strips 50, 52 along adjacent edges that are at right angles to one another (except where the strips meet). In this way, a series connection between the cells in different rows of the array is achieved. Although the cells in each row in a connected pattern are shown in series and the connections between the rows are completed at the ends of the rows, optionally at opposite sides of the array, It should be understood, however, that connections along any other path through a series of batteries can be used.

Figure 7a shows an array of substrates of photovoltaic cells having beveled corners, such as corners or rounded corners that are truncated by a slanted edge. These substrates are also known as semi-square substrates. When used in an array of substrates, the space left between the beveled corners of adjacent substrates remains the space used for the connection between the conductive sheets for adjacent cells.

Figure 7b shows an example of first and second conductor sheets 70, 72 for use on a beveled substrate (for illustration purposes, the sheets are shown to be slightly offset from each other, but preferably The edge covers the substrate The beveled portion of the edge). The insulating layers between the sheets and the holes for the connection through the sheets are not shown in detail.

The first conductor sheet 70 has an "ear portion" that extends beyond the substrate at one of the first and second adjacent corners of the substrate beyond its beveled portion. Thus, in the array, the portion of the ear extends into the space between the substrate and a first adjacent substrate that is left by the beveled portion. The second conductor sheet 72 has a similar "ear portion" that extends beyond the beveled portion of the substrate at a third and fourth corner of the substrate. Thus, in the array, the equal ear portions of the second conductor sheet extend into the space between the substrate and a second adjacent substrate on a side opposite the first adjacent substrate. Accordingly, the equal ear portions of the first conductor sheet 70 of the battery are electrically engageable to the ear portions of the second conductor sheet of the first adjacent battery, and the ears of the second conductor sheet 72 of the battery A portion is electrically bondable to the equal ear portion of the first conductor sheet of the second adjacent battery. Although the specific shape of one of the ear portions is shown by way of illustration, it should be appreciated that other shapes may be used: the ear portions need not extend into the entire space between the substrates, as long as Partial overlap considerations may be made by joining adjacent cells to the ear portions.

A photovoltaic cell of the first type comprises the substrate, a conductor sheet having an ear portion as shown, and an electrically insulating layer interposed between the conductor sheets. Any type of connection from the sheets to the substrate can be used as described. Batteries having the sheets of Figure 7b can be used in the array in which the continuous battery system is in series in one row or column. Other types of photovoltaic cells can have different configurations of ear portions to provide for different couplings pattern. For example, where the connection pattern is rotated, such as at the corners of the array, the ear portions can be provided for use with batteries located at opposite corners of the substrate.

Figure 7c shows first and second conductor sheets 70, 72 for use in a second type of photovoltaic cell having a beveled substrate. The first conductor sheet 70 is similar to that of FIG. 7b and has ear portions at adjacent first and second corners of the substrate. The second conductor sheet 72 has a single ear portion at a third corner of the substrate, oriented in a direction perpendicular to the equal ear portions of the first conductor sheet 70.

10‧‧‧Substrate

12,14,16,17‧‧‧Sheet

18‧‧‧Electrical connection materials

Claims (26)

A method of fabricating a photovoltaic cell, comprising: - providing first and second openings in a first conductive sheet; - providing third and fourth openings in a combination of a second conductive sheet and an electrically isolating sheet; Providing a stack of sheets on a substrate, the substrate comprising a semiconductor body of the photovoltaic cell, the stack comprising the first and second conductive sheets and an electrically isolating sheet, the first conductive sheet being disposed on the electrically isolating sheet and the substrate The electrically isolating sheet is disposed 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 in the stack, and the The third opening has a shape exposing the first conductive sheet around the first openings aligned with the third openings, and the fourth openings have a shape covering the fourth and fourth Circumscribing the circumference of the second openings; applying an electrical connection material through the first and third openings to connect the substrate to the first conductive sheet, and through the second and fourth openings to The substrate Connected to the second conductive sheet. The method of claim 1, wherein the stack comprises a further electrically isolating sheet disposed between the electrically isolating sheet and the further electrically isolating sheet, the further electrically isolating sheet having a further opening, Aligned with the third and fourth openings, the further openings having a shape such that the second conductive sheet is along the fourth openings Surrounded to be exposed, the further electrically isolating sheet covers the second electrically conductive sheet at least around the third opening. The method of claim 2, wherein the electrical connection material is applied to the further electrically isolating sheet and to the further openings, and is removed from the further electrically isolating sheet outside the further openings . The method of claim 1 or 2, wherein the electrical connection material is printed in an island portion seated in the third and fourth openings, the island portions located in the third openings along the The first opening extends around the first opening to the first conductive sheet, and the island portions located in the fourth openings extend around the fourth opening to the second conductive sheet. The method of claim 1 or 2, wherein the electrical connection material is a solder having a melting temperature at or below 150 degrees Celsius, or a heat curable material having a temperature at or below the temperature The step of applying the electrical connection material comprises heating the electrical connection material to either above the melting temperature or the curing temperature. The method of claim 1 or 2, wherein the electrically isolating sheet and the second electrically conductive sheet are along an edge at one side of the substrate, the end portion being shorter than the first conductive sheet, and the first conductive sheet is exposed One of the first ones. The method of claim 2, wherein the electrically isolating sheet, the second electrically conductive sheet, and the further electrically isolating sheet are exposed at an edge shorter than the first conductive sheet along an edge at one of the first sides of the substrate a first strip of the first conductive sheet; and the further electrically isolating sheet is along an edge at a second side of the substrate, the end being shorter than the second conductive sheet. The method of claim 1 or 2, comprising: - assembling the stack, the stack comprising the first and second electrically conductive sheets separated and aligned by the electrically isolating sheet; - placing the stack on a substrate. The method of claim 1 or 2, wherein the electrical connection material is a conductive adhesive. The method of any of the preceding claims, wherein the stack comprises an inner electrically isolating foil disposed between the first electrically conductive foil and the substrate, the inner electrically isolating foil having a further opening, and the first and second The openings are aligned. The method of claim 10, wherein the inner electrically isolating sheet is a thermoplastic polymer sheet and the thermoplastic polymer sheet is heated to a temperature, which is plastic when it is tied to the substrate, or It is provided at this temperature when it is applied to the substrate. The method of claim 11, wherein the electrical connection material is a solder or a heat curable material, and the thermoplastic polymer sheet is made by heating because the temperature is plastic or in a single processing step. In the case of plastic, the solder or heat curable material is applied or cured in a molten form. A photovoltaic cell comprising: - a substrate comprising a semiconductor body of the photovoltaic cell; - a first conductive sheet on the substrate, having first and second openings in the first conductive sheet; - An electrically isolating sheet on the first conductive sheet; a second conductive sheet on the electrically isolating sheet; - third and fourth openings in the combination of the second electrically conductive sheet and the electrically isolating sheet, the third and fourth openings being respectively associated with Aligning the first and second openings, wherein the third openings have a shape exposing the first conductive sheets around the first openings aligned with the third openings, and the fourth The opening has a shape that encompasses the circumference of the second openings that are aligned with the fourth openings; - the substrate is coupled to the first conductive sheet by electrical connection materials of the first and third openings, and The substrate is connected to the second conductive sheet through the second and fourth openings. A photovoltaic cell according to claim 13 comprising a further electrically isolating sheet on the second electrically conductive sheet, the further electrically isolating sheet having a further opening aligned with the third and fourth openings, the further The opening exposes the second conductive sheet along the periphery of the fourth openings, and the further electrically isolating sheet covers the second conductive sheet at least around the third openings. The photovoltaic cell of claim 13 or 14, wherein the electrically isolating sheet and the second electrically conductive sheet are shorter along the edge of one of the sides of the substrate than the first conductive sheet, and the first conductive is exposed One of the first pieces of the sheet. The photovoltaic cell of claim 14, wherein the electrically isolating sheet, the second electrically conductive sheet, and the further electrically isolating sheet are exposed along an edge of the first side of the substrate, the end being shorter than the first electrically conductive sheet, and being exposed a first strip of the first conductive sheet; and the further electrically isolating sheet is along an edge of the second side of the substrate, the end being shorter than the second conductive thin sheet. The photovoltaic cell of claim 16, wherein the first and second edges are parallel to each other. The photovoltaic cell of claim 17, wherein the first and second edges are adjacent edges of the substrate. A photovoltaic cell assembly comprising the first photovoltaic cell of any one of claims 14, 16, 17, or 18, and wherein the first photovoltaic cell is electrically connected to a second photovoltaic via the first strip battery. A photovoltaic cell assembly, comprising the first photovoltaic cell of any one of claims 16-18, wherein the first photovoltaic cell is electrically connected to a second and third via the first and second strips PV. The photovoltaic cell of claim 13, 14, 16, 17, or 18, wherein the fourth openings comprise secondary openings aligned in the second conductive sheet and the electrically isolating sheet, in the second conductive sheet The secondary openings extend to an edge of one of the fourth openings and the secondary openings in the electrically isolating sheet have an edge spaced from the edge of the fourth openings. The photovoltaic cell of any of claims 13-21, wherein the third openings comprise secondary openings aligned in the second conductive sheet and the electrically isolating sheet, the ones located in the electrically isolating sheet The secondary opening extends to an edge of one of the third openings, and the secondary openings in the second conductive sheet have an edge spaced from the edge of the fourth openings. The photovoltaic cell of any one of claims 13, 14, 16, 17, or 18, wherein the stack comprises an inner electrically isolating sheet disposed on the first electrically conductive sheet Between the substrate and the substrate, the inner electrically isolating sheet has a further opening aligned with the first and second openings. The photovoltaic cell of claim 23, wherein the inner electrically isolating sheet is a thermoplastic polymer sheet. The photovoltaic cell of any one of claims 13, 14, 16, 17, or 18, wherein the substrate has a beveled corner, the first and second electrically conductive sheets are each one of the beveled corners The second portion has a portion that extends beyond the substrate. An assembly of photovoltaic cells comprising an array of photovoltaic cells, the array comprising a first and second photovoltaic cell of claim 25, wherein the extended portion of the first conductive wafer of the first photovoltaic cell is associated with the The extended portions of the second electrically conductive sheets of the second photovoltaic cell are partially overlapped and electrically connected.