JP2018163988A - Solar cell module - Google Patents

Abstract

A high-power solar cell module is provided. SOLUTION: The solar cell module 200 includes a solar cell string 100 in which a plurality of solar cells 101 to 105 are connected by wiring members 82 to 85, a light receiving surface protection member 91 arranged on the light receiving surface side of the solar cell string, and The back surface protection member 92 is provided on the back surface side of the solar cell string. Each of the solar cells is a back surface junction solar cell having electrodes 61 and 62 only on the back surface side of a semiconductor substrate having a rectangular shape in plan view obtained by dividing a semiconductor substrate having a square shape in plan view into two. The solar cell having a rectangular shape in plan view includes a reflection portion 71 on the light receiving surface in a region corresponding to the outer peripheral region of the semiconductor substrate having a square shape in plan view. [Selection diagram] Figure 1

Description

  The present invention relates to a solar cell module.

  The back junction solar cell has a p-type region and an n-type region patterned in a predetermined shape on the back side of the semiconductor substrate, and electrodes are provided on these conductivity type regions. As a pattern shape of the conductive region in the back junction solar cell, a configuration in which p-type regions and n-type regions extending in one direction are alternately arranged along a direction orthogonal to the extending direction is common. .

  A solar cell module is obtained by sealing a solar cell string in which a plurality of solar cells are connected via a wiring material between a light-receiving surface protective material and a back surface protective material. In the back junction solar cell, the solar cell is connected in series by connecting the electrode provided in one n-type region of two adjacent solar cells and the electrode provided in the other p-type region to a wiring member. Is done.

  Since the back junction solar cell has an electrode only on the back surface of the semiconductor substrate and no electrode on the light receiving surface, there is no shadowing loss due to the electrode, and high conversion efficiency can be realized. On the other hand, in the back junction solar cell, recombination of photogenerated carriers is likely to occur at the end of the semiconductor substrate, and the utilization efficiency of the light irradiated to the end of the semiconductor substrate is low.

  For example, in the n-type region at the substrate end of a back junction solar cell using an n-type semiconductor substrate, most of the holes that are minority carriers recombine with electrons that are majority carriers, so that the n-type region at the edge of the substrate The recovery efficiency of carriers (electrons) at the electrode provided above is low. In Patent Document 1, a light reflecting material is provided on the light receiving surface of this region, and incident light is effectively used by making the reflected light incident on the other part of the solar cell (the central part of the semiconductor substrate). It is described that the conversion efficiency of the battery can be improved.

WO2010 / 021204 pamphlet

  An object of the present invention is to further increase the output of a back junction solar cell, particularly to improve module output.

  In the solar cell module of the present invention, a solar cell string in which a plurality of solar cells are connected by a wiring material, a light-receiving surface protective material disposed on the light-receiving surface side of the solar cell string, and a back surface side of the solar cell string A back surface protective material is provided. It is preferable that a sealing material is provided between the solar cell string and the light receiving surface protective material and between the solar cell string and the back surface side protective material, and the solar cell string is sealed with the sealing material. .

  Each of the solar cells constituting the solar cell string includes a semiconductor substrate having a rectangular shape in plan view obtained by dividing a semiconductor substrate having a square shape in plan view, and having electrodes only on the back side of the semiconductor substrate. This is a back junction solar cell having no electrode on the surface side. Each of the back junction solar cells having a rectangular shape in plan view includes a reflecting portion on a light receiving surface in a region corresponding to the outer peripheral region of the square-shaped semiconductor substrate in plan view before division.

  The solar cell module of the present invention can improve the output by increasing the amount of light incident on the region with high power generation efficiency by providing the reflecting member in the region with low power generation efficiency at the end of the back junction solar cell.

It is sectional drawing of the solar cell module of one Embodiment. It is a top view of the back surface side of the back junction solar cell contained in a solar cell module. It is a top view by the side of the light-receiving surface of the back junction solar cell contained in a solar cell module. It is a top view of the back surface side of a solar cell grid. It is a top view by the side of the light-receiving surface of a solar cell grid. It is a top view of the back surface side of the square-shaped solar cell before a division | segmentation. It is a conceptual diagram showing the mode of light reflection by the triangular prism-shaped reflection member. It is a conceptual diagram showing the mode of light reflection by the triangular prism-shaped reflection member. It is a conceptual diagram showing the mode of light reflection by the triangular prism-shaped reflection member.

  FIG. 1 is a schematic cross-sectional view of a solar cell module (hereinafter referred to as “module”) according to an embodiment of the present invention. A module 200 shown in FIG. 1 includes a solar cell string 100 in which a plurality of solar cells 101 to 105 (hereinafter referred to as “cells”) are electrically connected via wiring members 82 to 85. A light receiving surface protective material 91 is provided on the light receiving surface side (upper side in FIG. 1) of the solar cell string, and a back surface protective material 92 is provided on the back surface side (lower side in FIG. 1).

  As the cell, a back junction solar cell (back junction cell) is used. FIG. 2A is a plan view of the back surface side of the back surface bonded cell, and FIG. 2B is a plan view of the light receiving surface side of the back surface bonded cell. The back junction cell 103 included in the module 200 has a first conductivity type region and a second conductivity type region on the back side of a semiconductor substrate such as crystalline silicon. A first electrode 61 is provided on the first conductivity type region, and a second electrode 62 is provided on the second conductivity type region. One of the first conductivity type region and the second conductivity type region is p-type, and the other is n-type. The back junction cell does not have an electrode on the light receiving surface of the semiconductor substrate, and collects photocarriers (holes and electrons) generated on the semiconductor substrate by means of electrodes 61 and 62 provided on the back side of the semiconductor substrate.

  As shown in FIGS. 2A and 2B, the cell 103 has a rectangular shape having two long sides and two short sides in plan view. The rectangular cell is obtained, for example, by dividing the large cell 10 (see FIG. 4) using a semiconductor substrate having a square shape in plan view into two at the center dividing line C1-C2.

  FIG. 3A is a plan view of a back surface side of a solar cell grid in which a plurality of back surface junction cells are arranged in a grid shape. FIG. 3B is a plan view of the light receiving surface side of the solar cell grid. FIG. 1 corresponds to a cross-sectional view taken along the line II in FIGS. 3A and 3B.

  In the solar cell grid 180, the solar cell strings 100, 110, 120 in which a plurality of cells are connected along the first direction (x direction) are arranged along the second direction (y direction) orthogonal to the first direction. Is arranged in. The solar cell string 100 includes a plurality of cells 101 to 105 arranged in the first direction. A solar cell string is formed by electrically connecting the electrodes provided on the back side of the cell via the wiring members 82 to 85. A plurality of cells are connected in series by connecting the first electrode 61 of one of the two adjacent cells and the second electrode 62 of the other cell via a wiring material. The cells may be connected in parallel by connecting the first electrodes or the second electrodes of adjacent cells.

  In the solar cell string 100, the wiring member 81 disposed at one end portion in the first direction includes a lead wire 81a that can be connected to an external circuit. The wiring member 86 arranged at the other end in the first direction is connected to the solar cell string 110 adjacent in the second direction.

  In the module 200, the solar cell grid is sealed by filling the sealing material 95 between the protective materials 91 and 92. In the module, the cells are not necessarily arranged in a grid shape, and a solar cell string in which a plurality of cells are connected in a row may be sealed between the protective members 91 and 92.

[Cell structure and fabrication method]
FIG. 4 is a plan view of a large cell before division viewed from the back side. A large square cell does not need to be a perfect square. For example, a semi-square type as shown in FIG. 4 (a square having four rounded corners or a notch is present) ) As shown in FIGS. 2A and 2B, the rectangular cell obtained by dividing the semi-square type large format cell has notches 58 and 59 at both ends of one long side 51 of the rectangle.

  The length of one side of the square is, for example, about 20 to 200 mm. In a rectangular cell obtained by dividing a large square cell, the length of the long side of the rectangle is equal to the length of one side of the semiconductor substrate before the division, and is about 20 to 200 mm. The length of the short side of the rectangle is approximately ½ of the length of the long side, and is about 10 to 100 mm.

  Since the area of one rectangular cell obtained by the division is half of the area of the large cell before the division, the module voltage can be increased even when the module is installed in a small area. Further, since the area of one cell is halved, the current flowing through the wiring material is halved, the electrical loss due to the resistance of the wiring material can be reduced, and the output of the module can be improved.

  The large cell shown in FIG. 4 can be manufactured based on a known method of manufacturing a back junction cell. As the semiconductor substrate, for example, a square crystalline silicon substrate is used. Crystalline silicon may be single crystal or polycrystalline.

  A first conductivity type region and a second conductivity type region are provided on the back side of the semiconductor substrate. As described above, one of the first conductivity type region and the second conductivity type region is p-type and the other is n-type. These conductivity type regions can be formed by a method of providing a doping region in a semiconductor substrate or a method of forming a semiconductor thin film such as an amorphous silicon thin film on the semiconductor substrate. When a p-type or n-type semiconductor thin film is provided on a semiconductor substrate, an intrinsic semiconductor thin film such as an intrinsic amorphous silicon thin film is provided between the semiconductor substrate and the conductive semiconductor thin film, thereby providing a passivation effect on the surface of the semiconductor substrate. Is obtained. A first electrode 61 is provided on the first conductivity type region, and a second electrode 62 is provided on the second conductivity type region.

  The first electrode 61 and the second electrode 62 are preferably metal electrodes. A transparent conductive layer made of a metal oxide or the like may be provided between the semiconductor layer and the metal electrode. The metal electrode can be formed by a known method such as printing or plating. Specific examples of the metal electrode include an Ag electrode formed by screen printing of an Ag paste and a copper plated electrode formed by electrolytic plating.

  As shown in FIGS. 2A and 4, the first conductivity type region in which the first electrode 61 is provided and the second conductivity type region in which the second electrode 62 is provided are preferably patterned in a comb-teeth shape that meshes with each other. The first electrode 61 on the first conductivity type region patterned in a comb shape has a finger electrode portion 61a extending in the first direction (x direction) and a second direction (y direction) orthogonal to the first direction. And has a bus bar electrode portion 61b that connects the plurality of finger electrode portions 61a at the ends. Similarly, the second electrode 62 on the second conductivity type region patterned in a comb shape has a finger electrode portion 62a extending in the first direction and a bus bar electrode portion 62b extending in the second direction. .

  In the large cell 10 before division, finger electrode portions 61a and 62a are provided so as to extend in a direction orthogonal to the central dividing line (C1-C2 line), and the bus bar extends in parallel with the dividing line. It is preferable that the electrode parts 61b and 62b are provided. In this embodiment, the length of the finger electrode portions 61a and 62b of the rectangular cell after the division is about half that in the case of manufacturing one cell from a large square semiconductor substrate. Therefore, carrier recovery loss due to the line resistance of the finger electrode can be reduced.

  In the large cell 10, it is preferable to pattern the first conductivity type region and the second conductivity type region corresponding to two cells so as to be symmetrical with respect to the dividing line on one semiconductor substrate. That is, it is preferable that the bus bar electrode portions 61b of the first electrode 61 are provided at both ends in the first direction of the semiconductor substrate, and the bus bar electrode portions 62b of the second electrode 62 are provided at positions close to the center line. Thus, if a large cell is formed so as to have a symmetrical shape along the dividing line, the two divided cells (L-side cell and R-side cell) have the same pattern shape. Therefore, cell handling after division is easy, and it contributes to prevention of connection mistakes in the wiring material during string formation. In particular, as shown in FIG. 4, if a semi-square type large cell is divided into two to produce the rectangular cell shown in FIG. 2A, notches 58 and 59 are formed at both ends of the divided cell 103. The long side 51 side having the first conductivity type (the bus bar electrode part 61b side of the first electrode) and the long side 55 side not having the notch are the second conductivity type (the bus bar electrode part 61b side of the second electrode). Therefore, it is possible to reliably prevent connection mistakes.

  Two rectangular cells are obtained by cutting and dividing a square large cell along the central dividing line. The dividing method is not particularly limited. For example, the cell can be divided by a processing means such as a laser. A cell may be divided along the groove by forming a groove along the dividing line with a laser or the like and folding the substrate around the groove. The dividing groove may be formed on either the light receiving surface or the back surface of the cell.

  In the rectangular cell shown in FIG. 2A, one long side 55 is a side formed by cutting along the dividing line, and the bus bar electrode part 62b of the second electrode 62 is provided along the long side 55. Yes. A side surface in contact with the long side 55 of the cell is a side surface generated by the division. The other long side 51 is the same as one side 51 of the large cell before division, and the bus bar electrode portion 61 b of the first electrode 61 is provided along the long side 51. In the rectangular cell 103 after the division, the long side 51 is an outer peripheral portion of the square-shaped large cell before the division, and the side surface in contact with the long side 51 of the cell is the side surface (square shape) that existed before the division. The side surface of the semiconductor substrate. The two short sides 53 and 54 of the rectangular cell also correspond to the outer periphery of the large cell before division.

  In the outer peripheral area of a large cell, the thickness of the thin film tends to be non-uniform when the cell is manufactured. Further, the outer peripheral area of the large cell is likely to be rubbed or scratched on the surface during handling of the substrate during cell production. For this reason, the outer peripheral area of the large cell has a larger power generation loss due to carrier recombination and the like, and the power generation efficiency is lower than the central portion of the large cell.

As shown in FIG. 2B, a reflection portion 71 is provided along the long side 51 on the light receiving surface of the rectangular cell 103. As shown in FIG. 1, the light L <b> ₁ irradiated to the region of the cell 103 where the reflecting portion 71 is provided is reflected by the reflecting portion 71 and does not directly enter the cell 103. The light reflected by the reflecting portion 71 is re-reflected by the light receiving surface protection member 91 and the like, and enters the cell from the region where the reflecting portion is not provided, thereby contributing to power generation. The reflected light may be incident on other cells included in the module. In this way, by providing the reflective portion 71 in the region corresponding to the outer peripheral region of the large format cell, the power generation loss due to light irradiation to the region where the power generation efficiency is low is reduced, and the light reflected by the reflective portion 71 has high power generation efficiency. The module output can be improved by re-entering the region (normal region at the center in the surface of the cell).

  In the rectangular cell 103, the short sides 53 and 54 are the outer periphery of the large cell as in the case of the long side 51, and thus a reflecting portion may be provided in a region along the short sides 53 and 54.

  Since the long side 55 of the rectangular cell does not correspond to the outer periphery of the large cell, the outer peripheral region along the long side 55 is the outer peripheral region along the long side 51 and the outer peripheral region along the short sides 53 and 54. Compared with, power generation efficiency is high. On the other hand, the outer peripheral region along the long side 55 has reduced power generation efficiency due to exposure of the side surface of the semiconductor substrate by cutting along the dividing line of large cells, handling at the time of cutting, etc. There is. Therefore, the reflection part may also be provided in a region along the long side 55 formed by cutting.

  The material of the reflecting part 71 is not particularly limited as long as it can reflect light. Copper, aluminum, silver, gold, tin, and alloys thereof are preferable because of their high reflectance. The reflection part 71 may be a resin material provided with a reflective layer made of metal or the like on the surface as long as the light receiving surface side has light reflectivity. The reflective portion may be formed by printing a metal layer or the like on the light receiving surface, or the reflective portion may be provided on the light receiving surface by bonding the reflective member to the cell.

  The shape of the reflecting portion is not particularly limited, but it is preferable to have a slope in order to reflect light obliquely and increase the amount of reflected light incident on other portions of the cell. For example, it is possible to reflect light in an oblique direction by bonding a reflecting member having irregularities on the light receiving surface side surface to the light receiving surface of the cell. Further, a triangular prism-shaped reflecting member may be provided on the light receiving surface of the cell. The slope of the reflecting portion is not limited to a flat shape, and may be a curved surface. For example, a reflecting member having a semicircular cross section may be provided on the light receiving surface of the cell.

  By providing a triangular prism-shaped reflecting member whose angle formed between the joint surface (bottom surface) and the side surface (inclined surface) to the cell is within a predetermined range, the incident angle of the light reflected by the reflecting portion to the light receiving surface protection material 91 is growing. As a result, the reflectance at the interface between the light receiving surface protection member 91 and the air increases, and the amount of light reflected by the reflecting portion is reflected by the light receiving surface protection member 91 and enters the cell. The power generation efficiency of the module can be improved.

For example, when the incident angle of the light reflected by the reflecting portion to the light receiving surface protection material 91 is larger than the critical angle at the interface between the light receiving surface protection material and air, the light reflected by the reflecting portion is received by the light receiving surface. Since the light is totally reflected at the interface between the protective material and the air, the incident efficiency of the reflected light to the cell is improved. When glass (refractive index: about 1.5) is used as the light receiving surface protecting material, the critical angle is about 41 °. Therefore, if the 41 ° or higher incident angle theta _r to the light receiving surface protection member of the light reflected by the reflecting portion, the light at the interface between the light receiving surface protection member and the air is totally reflected.

Figure 5A, on the light receiving surface of the semiconductor substrate 50 constituting the cell, in the case where the angle theta ₁ between the bottom surface and the side surface is provided with a triangular prism shaped reflecting member 75 of 41 ° or more (e.g., about 60 °), the light receiving It is a conceptual diagram showing the mode of reflection of the light which injects into a module from a surface. The light L ₃₀ that has passed through the light receiving surface protective member 91 and the sealing material 95 and reached the reflecting member 75 at a small incident angle (and refraction angle) is reflected by the side surface of the reflecting member 75, and the reflected light L ₃₁ is reflected on the light receiving surface side. The light is incident on the semiconductor substrate 50 without being reflected. Incident light L ₄₀ having a refraction angle γ close to the critical angle is reflected by the side surface of the reflecting member 75 toward the light receiving surface. The incident angle θ _r of the reflected light L ₄₁ to the interface between the light receiving surface protecting member 91 and the air is larger than the inclination angle θ ₁ of the reflecting member. Therefore, if the inclination angle θ ₁ is equal to or greater than the critical angle (41 °), the reflected light L ₄₁ is totally reflected at the interface between the light-receiving surface protection material and air, and the re-reflected light L ₄₂ is incident on the semiconductor substrate 50. Contributes to power generation.

As described above, when the angle θ ₁ formed between the bottom surface and the side surface of the reflecting member is equal to or larger than the critical angle (41 °) at the interface between the air and the light receiving surface protection material 91, the side surface of the triangular prism-shaped reflecting member 75 is formed. The light that has arrived and reflected is incident on the semiconductor substrate 50 directly or after being totally reflected at the interface between the light-receiving surface protection member 91 and air, and is not emitted to the light-receiving surface side of the module. Therefore, substantially the entire amount of light reflected by the reflecting member can be made incident on a region where the power generation efficiency of the cell is high, and the output of the module is improved. Further, since the reflected light from the reflecting member 75 does not exit to the light receiving surface side of the module, the reflected light from the reflecting member is not visually recognized from the outside of the module, and the reflecting member looks black. Since the back contact cell is not provided with electrodes on the light receiving surface and is entirely black, the color of the reflective member and the color of the cell are unified with black, and the design of the module is improved.

5B is the case where the angle theta ₁ between the bottom surface and the side surface with a triangular prism shaped reflecting member 76 of 65.5 °, which is a conceptual diagram showing a state of reflection of light incident on the module from the light receiving surface. In any case where the refraction angle γ of the incident light L ₅₀ is 0 to 41 °, the reflected light L ₅₁ reflected by the side surface of the reflecting member 76 is incident on the semiconductor substrate 50 as it is without being reflected on the light receiving surface side. . That is, if the angle theta ₁ between the bottom surface and the side surface of the reflective member is not less than 65.5 °, the light reaching the side surface of the reflecting member, without being reflected on the light-receiving surface side, all of the reflected light, The light directly enters the semiconductor substrate 50 from the reflecting member. For this reason, the amount of light absorbed and scattered when passing through the sealing material 95 and the like after being reflected by the reflecting member is small, and the light utilization efficiency and design of the module are further improved.

If the angle θ ₁ formed between the bottom surface and the side surface of the reflecting member exceeds 65.5 °, improvement in light utilization efficiency and designability cannot be expected even if θ ₁ is further increased. On the other hand, if the angle theta ₁ between the bottom surface and the side surface of the reflecting member is excessively large, the apex angle becomes smaller with the height of the reflecting member increases, in order to reliably sealed by the sealing material 95, It is necessary to increase the thickness of the sealing material on the light receiving surface side. An increase in the thickness of the sealing material may cause a reduction in output of the module due to an increase in light absorption by the sealing material, in addition to an increase in cost. Therefore, the angle formed between the bottom surface and the side surface of the triangular prism-shaped reflecting member is preferably 70 ° or less. As will be described in detail later, by using a flexible material such as a transparent film as the light-receiving surface protective material, the thickness of the sealing material is excessively increased even when a triangular prism-shaped reflecting member is provided on the light-receiving surface of the cell. It is possible to reliably perform the sealing without increasing it.

As shown in FIGS. 5A and 5B, when the cross-sections of the reflecting members 75 and 76 are isosceles triangles with θ ₁ = θ ₂ , the orientation of the reflecting members is confirmed when the reflecting members are joined to the cells. Since it is not necessary, productivity can be improved. Note that the two base angles in the isosceles triangle need not be exactly the same, and may have a difference of about ± 2 °.

The reflecting member does not need to have an isosceles triangular cross section. For example, the slope angle θ _{2 of the} slope facing the gap between the adjacent cells may be larger than the slope angle θ _{1 of the} slope facing the center side of the cell. For example, like the reflection member 77 shown in FIG. 5C, the angle formed between the side surface and the bottom surface facing the gap between adjacent cells may be a right angle. The angle formed between the side surface and the bottom surface facing the gap between adjacent cells may be an obtuse angle.

  The region where the reflecting portion 71 is provided on the light receiving surface is preferably within 3 mm from the outer periphery of the cell. If the reflective part is also provided in an area where the width of the reflective part is large and the distance from the outer periphery is large, the reflective member overlaps the normal area with high power generation efficiency, so the module output may be reduced due to the reduction in the power generation area . On the light receiving surface, it is preferable that the reflecting portion 71 is provided in a region of 0.1 mm or more from the outer periphery of the cell. 0.1-3 mm is preferable and, as for the width | variety of the reflection part 71 on the light-receiving surface of a cell, 0.5-2 mm is more preferable.

  The reflection part 71 may protrude from the outer periphery of the cell and may be provided in a gap portion between adjacent cells. By providing the reflection part 71 that protrudes from the outer periphery of the cell, light applied to the gap can be reflected by the reflection part 71 and incident on the normal part of the cell, so that the light utilization efficiency is improved. Module output is improved. What is necessary is just to set the protrusion width | variety of the reflection member from the outer periphery of a cell in the range which does not produce a short circuit with an adjacent cell, for example, is about 0.1-2 mm.

  As described above, in the rectangular cell, the long side 51, the short side 53, and the short side 54 correspond to the outer periphery of the large-sized cell. The reflection part should just be provided in the area | region along those sides. In addition, it is not necessary that the reflective portion is provided in the entire region along one side, and the reflective portion may be provided in a partial region along the side. From the viewpoint of effectively improving the module output, it is preferable that the reflecting portion 71 is provided in a region of half or more along the direction of the long side 51.

  The planar view shape of the reflection part is not particularly limited. In order to cover the outer peripheral region with low power generation efficiency with a certain width, the reflecting portion is preferably rectangular in plan view. The length of the long side of the rectangular reflection part in plan view is preferably 50% or more of the length of one side of the cell, more preferably 70% or more, and further preferably 80% or more. preferable. The length of the short side of the rectangle (the width of the reflecting portion) is set to a region within 3 mm from the outer periphery of the cell in consideration of the width of the reflecting portion provided in the gap between the adjacent cells and protruding from the outer periphery of the cell. What is necessary is just to set so that a reflection part may cover.

  Formation of the reflective portion on the light receiving surface of the cell may be performed at the stage of producing a large square cell, or the reflective portion may be formed on the light receiving surface after being divided into rectangular cells. In addition, after creating a solar cell string (or grid) by connecting a plurality of cells, a reflecting portion may be provided on the light receiving surface of each cell. When providing a reflective part by printing, it is preferable to provide a reflective part before a division | segmentation. When joining a reflecting member, it is preferable to join a reflecting member to the light receiving surface of the cell after division. As described above, it is easy to improve the light utilization efficiency by adjusting the inclination angle of the slope, etc., and it is possible to form a reflection part that protrudes from the outer periphery of the cell. It is preferable to provide a reflecting portion.

  The method for joining the reflecting member to the light receiving surface of the cell is not particularly limited. In the case where the bottom surface of the reflecting member (the bonding surface with the cell) has conductivity, it is preferable to prevent leakage by bonding a wiring material to the light receiving surface of the cell using an insulating adhesive.

[Production of solar cell string]
A solar cell string is obtained by electrically connecting the divided rectangular cells via a wiring member. A solar cell grid is obtained by connecting a plurality of strings in a direction orthogonal to the string extending direction.

  The wiring material is not particularly limited as long as it is conductive. From the viewpoint of conductivity, metals such as copper, aluminum, silver, gold, and alloys thereof are preferable. The surface of the wiring material may be covered with solder or the like. Examples of the shape of the wiring material include a flat wire shape, a sheet shape, and a wire shape.

  The wiring member and the cell electrodes 61 and 62 can be connected via solder, a conductive adhesive, a conductive film, or the like. As shown in FIGS. 3A and 3B, when the connection direction of the cells 101 to 105 in the string 100 is parallel to the short side direction of the rectangle, the amount of current is half that of the square cell before division, The width of the wiring material can be set to be equivalent to the case of connecting square cells. Therefore, the amount of current per unit cross-sectional area of the wiring material is small, and the electrical loss due to resistance is reduced.

  As described above, a reflective part may be provided on the light receiving surface of the cell after the wiring material and the cell are connected to form the string. By providing the reflective portion after the string is formed, it is possible to reliably suppress leakage caused by the contact of the reflective material to the adjacent cells. In particular, when the reflective portion is provided so as to protrude from the outer periphery of the cell, the reflective portion is preferably provided on the light receiving surface of the cell after the string is formed.

[modularization]
In a state where the sealing material and the protective material are arranged and laminated on the light receiving surface side and the back surface side of the solar cell string (or grid), vacuum lamination is performed, and the sealing material is brought into close contact with the solar cell string and the protective material. After that, the sealing material flows in the gaps between the solar cells and the end of the module by thermocompression bonding, and the solar cell string is sealed.

  As the sealing material 95, a polyethylene resin composition mainly composed of an olefin elastomer, polypropylene, ethylene / α-olefin copolymer, ethylene / vinyl acetate copolymer (EVA), ethylene / vinyl acetate / triallyl. It is preferable to use a transparent resin such as isocyanurate (EVAT), polyvinyl butyrate (PVB), silicon, urethane, acrylic, or epoxy. The materials of the sealing material on the light receiving surface side and the back surface side may be the same or different.

  The light receiving surface protecting member 91 is light transmissive, and glass, transparent plastic, or the like is used. The back surface protective material 92 may be any of light transmitting property, light absorbing property, and light reflecting property. As the light-reflecting back surface protective material, a material exhibiting a metallic color or white color is preferable, and a white resin film, a laminate in which a metal foil such as aluminum is sandwiched between resin films, and the like are preferably used. As the light-absorbing protective material, for example, a material including a black resin layer is used.

  In a general solar cell module, a glass plate is often used as the light-receiving surface protection member 91, but a flexible resin film may be used. When the reflecting portion provided on the light receiving surface of the cell is a triangular prism-shaped reflecting member, by using a flexible transparent film as the light receiving surface protecting material 91, the light receiving surface protecting material follows the shape of the reflecting member. Because of the deformation, even when the height of the reflecting member is large or the apex angle of the reflecting member is small, the thickness of the light receiving surface side sealing material between the reflecting portion and the light receiving surface protective material is locally reduced. Can be prevented. Therefore, sealing can be reliably performed without excessively increasing the thickness of the sealing material. When a flexible transparent film is used as the light-receiving surface protection member 91, the thickness of the film is preferably 1 mm or less in order to deform the film along the shape of the reflecting portion.

DESCRIPTION OF SYMBOLS 10 Large format solar cell 50 Semiconductor substrate 61, 62 Electrode 71 Reflection part 75-77 Reflection member 81-86 Wiring material 101-105 Solar cell 100,110,120 Solar cell string 91 Light-receiving surface protection material 92 Back surface protection material 95 Sealing material 200 Solar cell module 201 Wiring material

Claims (13)

A solar cell having a solar cell string in which a plurality of solar cells are connected by a wiring material, a light receiving surface protective material disposed on the light receiving surface side of the solar cell string, and a back surface protective material disposed on the back surface side of the solar cell string A battery module,
Each of the solar cells has an electrode only on the back surface side of the semiconductor substrate having a rectangular shape in plan view obtained by dividing the semiconductor substrate having a square shape in plan view into two, and has no electrode on the light receiving surface side. Without
The solar cell module in which the reflection part is provided on the light-receiving surface of the area | region corresponded to the outer peripheral area | region of the said square-shaped semiconductor substrate in planar view. The rectangular semiconductor substrate in plan view has a notch at both ends of one long side,
The solar cell module according to claim 1, wherein the reflection portion is provided on a light receiving surface in an outer peripheral region along a long side having a notch portion at both ends.   In the solar cell string, two adjacent cells have a long side having a notch portion of a semiconductor substrate of one solar cell and a long side not having a notch portion of a semiconductor substrate of the other solar cell. The solar cell module of Claim 2 arrange | positioned so that it may oppose.   The solar cell module according to any one of claims 1 to 3, wherein the reflection portion is bonded to a light receiving surface of the solar cell via an insulating adhesive.   The solar cell module according to any one of claims 1 to 4, wherein the reflecting portion has an inclined surface on a light receiving surface side.   The solar cell module according to claim 5, wherein unevenness is provided on a light receiving surface side surface of the reflecting portion.   The solar cell module according to claim 5, wherein the reflecting portion has a triangular prism shape.   8. The solar cell module according to claim 7, wherein at least one of the inclined surfaces of the reflective portion has an angle formed by a reflection member joining surface with the solar cell of 65.5 ° or more.   The solar cell module according to claim 7 or 8, wherein the reflecting portion has an isosceles triangular cross section.   9. The tilt angle of a slope facing the gap between adjacent solar cells among the two slopes of the reflecting portion is larger than the slope angle of the slope facing the center side of the solar cell. Solar cell module.   The solar cell module according to any one of claims 1 to 10, wherein the reflection portion is provided in a portion of a gap between an adjacent solar cell that protrudes from an outer periphery of the solar cell.   The solar cell module according to any one of claims 1 to 11, wherein a region where the reflecting portion is provided on the light receiving surface of the solar cell is within 3 mm from an outer periphery of the solar cell. The solar cell module according to any one of claims 1 to 12, wherein the light-receiving surface protective material is a flexible transparent film.

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