JP2021177511A - Solar cell, solar cell module, and solar cell manufacturing method - Google Patents

Abstract

To provide a solar cell that can reduce a gap and a step between solar cells.SOLUTION: A solar cell 10 according to an embodiment of the present invention includes a semiconductor substrate 11, and a pair of opposite end faces A3 and A4 of the semiconductor substrate 11 is inclined such that the edge of a first main surface A1 of the semiconductor substrate 11 is offset with respect to the edge of a second main surface A2 of the semiconductor substrate 11 in a certain direction and by a certain distance in a plan view.SELECTED DRAWING: Figure 1

Description

The present invention relates to a solar cell, a solar cell module, and a method for manufacturing a solar cell.

Solar cell modules are manufactured using solar cell strings in which a plurality of solar cell cells are arranged side by side and electrically connected in series. In such a solar cell string, adjacent solar cells are often connected by a conductive member (interconnector). In the case of a double-sided electrode type solar cell in which electrodes having different polarities are provided on the front and back surfaces (light receiving surface and opposite surface), the electrode on the front surface side of one solar cell and the electrode on the back surface side of the adjacent solar cell. And need to be connected. In this case, it is necessary to provide a gap for passing the interconnector between the solar cells, the effective area contributing to photoelectric conversion is limited, and the gap between the solar cells is conspicuous, which spoils the aesthetic appearance.

As a configuration for increasing the effective area of the solar cell string, for example, as described in Patent Document 1, the electrodes on the back side of the solar cell and the sun on the back side are stacked on the front side by overlapping the ends of the solar cell. A configuration called a single ring structure is known in which the electrodes on the surface side of the battery cell are directly connected.

International Publication No. 2015/152020

In the single ring structure, no gap is formed between the solar cells, but a step is generated between the solar cells, so that individual solar cells are still easily recognized. Further, in the single ring structure, stress tends to be concentrated on the portion where the solar cells overlap, so that the risk of damage to the solar cells or separation between the solar cells increases. Therefore, it is an object of the present invention to provide a solar cell, a solar cell module capable of reducing gaps and steps between solar cells, and a method for manufacturing a solar cell capable of constituting them.

The solar cell according to one aspect of the present invention includes a semiconductor substrate, and the pair of facing end faces of the semiconductor substrate have the edge of the first main surface of the semiconductor substrate as the second main surface of the semiconductor substrate in a plan view. It is tilted so as to be offset in a certain direction and by a certain distance with respect to the edge of the surface.

In the solar cell according to one aspect of the present invention, the pair of end faces are located on the inner adjacent surface substantially perpendicular to the first main surface and the second main surface, and on the outer side of the inner adjacent surface. An intermediate surface that connects the first main surface and the outer adjacent surface substantially perpendicular to the second main surface, the inner adjacent surface and the outer adjacent surface, and is substantially parallel to the first main surface and the second main surface. It may be a two-step stepped shape having and.

The solar cell according to one aspect of the present invention has a first semiconductor layer laminated on the first main surface and a second semiconductor layer laminated on the second main surface and having a different conductive type from the first semiconductor layer. The inner adjacent surface and the intermediate surface may be covered with the first semiconductor layer or the second semiconductor layer, and the outer adjacent surface may expose the semiconductor substrate.

The solar cell according to one aspect of the present invention may further include a first transparent electrode layer covering the first semiconductor layer and a second transparent electrode covering the second semiconductor layer.

The solar cell module according to one aspect of the present invention includes a plurality of the above-mentioned solar cells, and the inner adjacent surface of the solar cell faces the outer adjacent surface of the adjacent solar cell.

The solar cell module according to one aspect of the present invention may further include a conductive adhesive arranged between the opposing end faces of two adjacent solar cells.

The method for manufacturing a solar cell according to one aspect of the present invention includes a step of forming a first groove on a first main surface of a semiconductor wafer and a plane position shifted from the first groove on the second main surface of the semiconductor wafer. A step of forming a second groove parallel to the first groove, a step of laminating a first semiconductor material so as to cover the first main surface of the semiconductor wafer and the inner surface of the first groove, and the step of laminating the semiconductor wafer. A step of laminating a second semiconductor material having a different conductive type from the first semiconductor material so as to cover the second main surface and the inner surface of the second groove, and the first groove and the second groove of the semiconductor wafer. A step of removing a straddling region is provided.

According to the present invention, the gaps and steps between solar cells can be reduced.

It is a schematic cross-sectional view which shows the solar cell which concerns on one Embodiment of this invention. It is a flowchart which shows the procedure of the solar cell manufacturing method which concerns on one Embodiment of this invention. It is a schematic cross-sectional view which shows one process of the solar cell manufacturing method of FIG. It is a schematic cross-sectional view which shows the next process of FIG. 3 of the solar cell manufacturing method of FIG. It is a schematic cross-sectional view which shows the next process of FIG. 4 of the solar cell manufacturing method of FIG. It is a schematic cross-sectional view which shows the next process of FIG. 5 of the solar cell manufacturing method of FIG. It is a schematic cross-sectional view which shows the next process of FIG. 6 of the solar cell manufacturing method of FIG. It is a schematic cross-sectional view which shows the next process of FIG. 7 of the solar cell manufacturing method of FIG. It is a schematic cross-sectional view of the solar cell module which has the solar cell of FIG. It is a schematic cross-sectional view which shows the solar cell which concerns on embodiment different from FIG. 1 of this invention. It is a schematic cross-sectional view of the solar cell module which has the solar cell of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the same reference numerals are given to the same or corresponding parts in each drawing. Further, for the sake of simplification, illustrations, symbols, etc. of the members may be omitted, but in such cases, other drawings shall be referred to.

FIG. 1 shows a solar cell 10 according to an embodiment of the present invention. The solar cell 10 has a semiconductor substrate 11, a first semiconductor layer 12 laminated on a first main surface (light receiving surface) S1 on the front side of the semiconductor substrate 11, and a second main surface (back surface) on the back side of the semiconductor substrate 11. A second semiconductor layer 13 laminated on S2 and having a different conductive type from the first semiconductor layer, a first transparent electrode 14 covering the first semiconductor layer 12, and a second main surface of the second semiconductor layer 13 are laminated. 2 The transparent electrode 15 and the like are provided.

The pair of opposite end faces (first end face A3 and second end face A4) of the semiconductor substrate 11 have the edge of the first main face A1 in a certain direction and a certain distance with respect to the edge of the second main face A2 in a plan view. Tilt as a whole to offset only. In the present embodiment, the pair of end faces A3 and S4 are formed in a two-step step shape. Specifically, the first end surface A3 of the semiconductor substrate 11 is located outside the first inner adjacent surface A31 and the first inner adjacent surface A31 which are substantially perpendicular to the first main surface A1 and the second main surface A2. , The first outer adjacent surface A32 substantially perpendicular to the first main surface A1 and the second main surface A2, the first inner adjacent surface A31 and the first outer adjacent surface A32 are connected, and the first main surface A1 and the second It has a first intermediate surface A33 that is substantially parallel to the main surface A2. The second end surface A4 is located outside the second inner adjacent surface A41 and the second inner adjacent surface A41 which are substantially perpendicular to the first main surface A1 and the second main surface A2, and the first main surface A1 and the second surface A4. A second surface that connects the second outer adjacent surface A42 that is substantially perpendicular to the main surface A2, the second inner adjacent surface A41, and the second outer adjacent surface A42, and is substantially parallel to the first main surface A1 and the second main surface A2. It has an intermediate surface A43 and. The term "offset" means that only the position is different without substantially changing the shape and orientation. "Approximately vertical" and "approximately parallel" mean within ± 15 ° with respect to the exact "vertical" and "parallel".

The first inner adjacent surface A31 and the first intermediate surface A33 are covered with the first semiconductor layer 12 and the first transparent electrode 14, and the second inner adjacent surface A31 and the first intermediate surface A33 are the second semiconductor layer 13 and the first transparent electrode 14. 2 Covered by a transparent electrode 15. On the other hand, the first outer adjacent surface A32 and the second outer adjacent surface A42 are not covered with other components and expose the semiconductor substrate 11.

The semiconductor substrate 11 functions as a photoelectric conversion substrate that absorbs incident light from the light receiving surface side to generate optical carriers (electrons and holes). The semiconductor substrate 11 is formed of a crystalline silicon material such as single crystal silicon or polycrystalline silicon. The semiconductor substrate 11 is, for example, an n-type semiconductor substrate in which a crystalline silicon material is doped with an n-type dopant. Examples of the n-type dopant include phosphorus (P). By using crystalline silicon as the material of the semiconductor substrate 11, a relatively high output (stable output regardless of the illuminance) can be obtained even when the dark current is relatively small and the intensity of the incident light is low.

The first semiconductor layer 12 and the second semiconductor layer 13 attract carriers generated inside the semiconductor substrate 11 to collect charges having different polarities from each other. The first semiconductor layer 12 and the second semiconductor layer 13 can be formed of amorphous silicon doped with a dopant that imparts a desired conductive type. Examples of the p-type dopant include boron (B), and examples of the n-type dopant include phosphorus (P).

The first transparent electrode 14 and the second transparent electrode 15 are conductors that take out the electric charges collected by the first semiconductor layer 12 and the second semiconductor layer 13 and output them to the outside. The first transparent electrode 14 and the second transparent electrode 15 can be formed of the same material. Examples of the material forming the first transparent electrode 14 and the second transparent electrode 15 include ITO (Indium Tin Oxide) and zinc oxide (ZnO).

The solar cell 10 of the present embodiment can be manufactured by one embodiment of the solar cell manufacturing method according to the present invention. As shown in FIG. 2, the solar cell manufacturing method of the present embodiment includes a first groove forming step of the step, a second groove forming step of the step, a first semiconductor material laminating step of step S3, and a step S4. The second semiconductor material laminating step, the transparent electrode material laminating step of step S5, and the semiconductor wafer partial removal step of step S6 are provided.

In the first groove forming step of the step, as shown in FIG. 3, the first groove G1 is formed on the first main surface of the large-sized semiconductor wafer W from which the semiconductor substrate 11 can be cut out. The first groove G1 has a square cross section, one side wall constitutes the first inner adjacent surface A31, and the bottom wall constitutes the first intermediate surface A33. The first groove G1 can be formed by, for example, laser irradiation, cutting, etching, or the like.

The depth of the first groove G1 is preferably approximately 1/2 the thickness of the semiconductor wafer W, and even if the first semiconductor layer 12 and the first transparent electrode 14 are laminated, the depth is 1/2 or less of the thickness of the semiconductor wafer W. It is more preferable that the thickness is slightly larger than 1/2 of the thickness of the semiconductor wafer W.

In the second groove forming step of the step, as shown in FIG. 4, a second groove G2 parallel to the first groove G1 is formed on the second main surface of the semiconductor wafer W by shifting the plane position from the first groove G1. .. The second groove G2 has a square cross section, one side wall constitutes the second inner adjacent surface A41, and the bottom wall constitutes the second intermediate surface A43. The second groove G2 can be formed in the same manner as the first groove G1. The depth of the second groove G2 can be the same as the depth of the first groove G1.

In the first semiconductor material laminating step of step S3, as shown in FIG. 5, the first semiconductor material M1 forming the first semiconductor layer 12 so as to cover the first main surface of the semiconductor wafer W and the inner surface of the first groove G1. Are laminated. The first semiconductor material M1 can be laminated by, for example, a film forming technique such as CVD.

In the second semiconductor material laminating step of step S4, as shown in FIG. 6, the material that forms the second semiconductor layer 13 so as to cover the second main surface of the semiconductor wafer W and the inner surface of the second groove G2, that is, the first A second semiconductor material M2 having a different conductive type from the semiconductor material M1 is laminated. The lamination of the second semiconductor material M2 can be performed by the same film forming technique as the lamination of the first semiconductor material M1.

In the transparent electrode material laminating step of step S5, as shown in FIG. 7, the transparent electrode forming the first transparent electrode 14 and the second transparent electrode 15 in the layer of the first semiconductor material M1 and the layer of the second semiconductor material M2, respectively. The material M3 is laminated. The transparent electrode material M3 can be laminated by, for example, a film forming technique such as CVD or PVD.

In the semiconductor wafer partial removal step of step S6, as shown in FIG. 8, the region of the semiconductor wafer W straddling the first groove G1 and the second groove G2 is removed. As a result, a plurality of solar cell 10s can be obtained. Partial removal of the semiconductor wafer W can be performed by, for example, laser irradiation, milling, etching, or the like.

FIG. 9 shows a solar cell module 100 according to an embodiment of the present invention. The solar cell module 100 includes a solar cell string 110 having a plurality of solar cell cells 10, a surface protective material 120 that covers the front surface side (light receiving surface side) of the solar cell string 110, and a back surface that covers the back surface side of the solar cell string 110. A protective material 130 and a sealing material 140 that is filled between the front surface protective material 120 and the back surface protective material 130 and covers the solar cell string 110 are provided.

The solar cell string 110 is formed by arranging a plurality of solar cells 10 in a row and electrically connecting them in series. The two adjacent solar cells 10 are adhered to each other by a conductive adhesive 20 such as silver paste, which is arranged between the first end face and the second end face facing each other. In the present embodiment, the conductive adhesive 20 is mainly arranged between the first inner adjacent surface AA31 and the second outer adjacent surface A42 facing each other, and the solar cell 10 on the second outer adjacent surface A42 side. It is arranged so as not to come into contact with the first semiconductor layer 12 and the first transparent electrode 14. As a result, the first semiconductor layer 12 and the first transparent electrode 14 of the solar cell 10 on the first inner adjacent surface A31 side and the second semiconductor layer 13 and the second semiconductor layer 13 and the second transparent electrode 14 of the solar cell 10 on the second outer adjacent surface A42 side. The transparent electrode 15 is connected.

The surface protective material 120 protects the solar cell 10 by covering the surface of the solar cell string 110, that is, the solar cell 10 via the sealing material 140. The surface protective material 120 can be formed from a plate-shaped or sheet-shaped material, and is preferably excellent in translucency and weather resistance. Specifically, as the material of the surface protective material 120, for example, a transparent resin such as an acrylic resin or a polycarbonate resin, glass, or the like can be mentioned. Further, the surface of the surface protective material 120 may be processed into an uneven shape or coated with an antireflection coating layer in order to suppress the reflection of light.

The back surface protective material 130 protects the solar cell 10 by covering the back surface of the solar cell string 110 with the sealing material 140. Like the front surface protective material 120, the back surface protective material 130 can be formed from a plate-like or sheet-like material, and is preferably excellent in water impermeability. Specifically, the back surface protective material 130 includes, for example, a resin film such as polyethylene terephthalate (PET), polyethylene (PE), an olefin resin, a fluorine-containing resin, and a silicone resin, and a metal such as such a resin film and an aluminum foil. A laminate with a foil or the like is preferably used.

The sealing material 140 seals and protects the solar cell string 110, that is, the solar cell 10, and particularly prevents moisture from coming into contact with the solar cell 10. Therefore, the sealing material 140 is interposed between the light receiving side surface of the solar cell 10 and the surface protective material 120, and between the back surface of the solar cell 10 and the back surface protective material 130.

The sealing material 140 protects the solar cell 10 by adhering the solar cell string 110, the front surface protective material 120, and the back surface protective material 130, and eliminating the gap around the solar cell string 110. Therefore, examples of the sealing material 140 include ethylene / vinyl acetate copolymer (EVA), ethylene / α-olefin copolymer, ethylene / vinyl acetate / triallyl isocyanurate (EVAT), and polyvinyl butyral (PVB). ), Acrylic resin, urethane resin, or a translucent thermoplastic resin such as silicone resin is preferably used.

The solar cell module includes a surface protective material 120, a first sheet made of a thermoplastic resin forming a sealing material 140, a solar cell string 110, a second sheet made of a thermoplastic resin forming a sealing material 140, and a back surface. The protective material 130 is laminated in this order, and the laminated body is hot-pressed to melt and integrate the first sheet and the second sheet.

As described above, the solar cells 10 in which the edge of the first main surface A1 is offset with respect to the edge of the second main surface A2 can be arranged and connected without leaving a gap, so that the solar cell string 110 and thus the solar cell string 110 can be connected. The effective area that contributes to photoelectric conversion in the solar cell module 100 can be increased. Further, since the solar cell 10 can be connected without providing a step, the risk of damage due to stress concentration in the solar cell module 100 is small. Further, the solar cell string 110 in which the solar cells 10 are connected without providing a step is excellent in aesthetics because the seams between the solar cells 10 are inconspicuous.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and modifications can be made.

In the solar cell according to the present invention, the pair of end faces that offset the edge edges of the first main surface and the second main surface of the semiconductor substrate may be inclined as a whole, and have a stepped shape as in the above-described embodiment. It is not limited to the one, and may be an inclined flat surface or a curved surface.

The solar cell according to the present invention is not limited to the double-sided electrode type solar cell as in the above embodiment, and may be, for example, a back electrode type solar cell, a PERC (Passivated Emitter and Rear Cell), or the like. ..

In the solar cell according to the above-described embodiment, the transparent electrode can be omitted. In particular, since the n-type semiconductor layer has relatively excellent conductivity, the internal resistance does not easily increase even if the transparent electrode laminated on the n-type semiconductor layer is omitted, and the p-type transparent layer is transparent when the area of the solar cell is small. Even if the electrodes are omitted, the increase in resistance is small.

Further, the solar cell according to the present invention may include transparent electrodes 14R and 15R laminated except for the intermediate surfaces A33 and A44, for example, as in the solar cell 10R shown in FIG. In this case, the transparent electrodes 14R and 15R can be patterned by using a photolithography technique or the like. Specifically, in the transparent electrode material laminating step, masks may be arranged on the bottom surfaces of the first groove and the second groove to selectively laminate the transparent electrode materials, and the first semiconductor material and the second semiconductor material may be laminated. After laminating the transparent electrode material on the entire surface, a mask may be arranged to selectively remove the transparent electrode material on the bottom surface portion of the first groove 1 and the second groove. When the semiconductor wafer partial removal step is performed using a laser, it is possible to suppress performance deterioration due to the influence of the laser by irradiating the laser from the side where the transparent electrode materials are not laminated.

In the solar cell module according to the above-described embodiment, the solar cell cells are electrically connected in series, but the solar cell cells may be electrically connected in parallel. When the solar cells according to the present invention are connected in parallel, it is preferable to connect the first semiconductor layer and the second semiconductor layer having the same conductive type as the semiconductor substrate to each other. Specifically, for example, as in the solar cell module 100R shown in FIG. 11, the solar cell 10R of FIG. 10 is used to face the inner adjacent surface on which the semiconductor substrate and the semiconductor layer having the same conductive type are laminated. By arranging the conductive adhesive 20R between the outer adjacent surfaces, the semiconductor substrate and the semiconductor layers having the same conductive type are electrically connected to each other, whereby the solar cells according to the present invention are connected in parallel. The battery string 110R can be formed.

Further, in the solar cell module according to the present invention, the conductive adhesive connecting two adjacent solar cell cells may be arranged mainly between the intermediate surfaces facing each other.

10 Solar cell 11 Semiconductor substrate 12 1st semiconductor layer 13 2nd semiconductor layer 14 1st transparent electrode 15 2nd transparent electrode 20 Conductive adhesive 100 Solar cell module 110 Solar cell string 120 Front surface protection material 130 Back surface protection material 140 Seal Stopper A1 1st main surface A2 2nd main surface A3 1st end surface A4 2nd end surface A31 1st inner adjacent surface A32 1st outer adjacent surface A33 1st intermediate surface A41 2nd inner adjacent surface A42 2nd outer adjacent surface A43 Second intermediate surface

Claims (7)

Equipped with a semiconductor substrate,
The pair of facing end faces of the semiconductor substrate are inclined so that the edge of the first main surface of the semiconductor substrate is offset from the edge of the second main surface of the semiconductor substrate in a certain direction and by a certain distance in a plan view. Solar cell to do. The pair of end faces are located on the inner adjacent surface substantially perpendicular to the first main surface and the second main surface, and on the outer side of the inner adjacent surface, and are substantially on the first main surface and the second main surface. It is a two-step stepped shape having a vertical outer adjacent surface, connecting the inner adjacent surface and the outer adjacent surface, and having an intermediate surface substantially parallel to the first main surface and the second main surface. The solar cell according to claim 1. The first semiconductor layer laminated on the first main surface and
A second semiconductor layer laminated on the second main surface and having a different conductive type from the first semiconductor layer,
With more
The inner adjacent surface and the intermediate surface are covered with the first semiconductor layer or the second semiconductor layer.
The solar cell according to claim 2, wherein the outer adjacent surface exposes the semiconductor substrate. The solar cell according to claim 3, further comprising a first transparent electrode layer covering the first semiconductor layer and a second transparent electrode covering the second semiconductor layer. A plurality of solar cells according to any one of claims 2 to 4 are provided.
A solar cell module in which the inner adjacent surface of the solar cell faces the outer adjacent surface of the adjacent solar cell. The solar cell module according to claim 5, further comprising a conductive adhesive arranged between the opposing end faces of the two adjacent solar cells. The process of forming the first groove on the first main surface of the semiconductor wafer and
A step of forming a second groove parallel to the first groove on the second main surface of the semiconductor wafer by shifting the plane position from the first groove.
A step of laminating a first semiconductor material so as to cover the first main surface of the semiconductor wafer and the inner surface of the first groove, and a step of laminating the first semiconductor material.
A step of laminating a second semiconductor material having a different conductive type from the first semiconductor material so as to cover the second main surface of the semiconductor wafer and the inner surface of the second groove.
A step of removing a region straddling the first groove and the second groove of the semiconductor wafer, and
A method for manufacturing a solar cell.

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