JP6809816B2 - Solar cell module - Google Patents

Description

The present invention relates to a solar cell module in which a plurality of solar cells are electrically connected.

The solar cell has metal electrodes on the light receiving surface and the back surface. In the solar cell module, the electrodes of adjacent solar cells are electrically connected via a wiring material, so that a plurality of solar cells are electrically connected to form a solar cell string. The modularization of the solar cell is performed by sealing the solar cell string to which the plurality of solar cells are connected between the glass plate on the light receiving surface side and the back sheet on the back surface side.

The metal electrodes on the light receiving surface of a general solar cell are provided in a grid shape including a plurality of thin finger electrodes for collecting optical carriers and bus bar electrodes orthogonal to the finger electrodes. The busbar electrode is wider than the finger electrode, and a strip-shaped wiring material (referred to as "tab wire") is provided on the busbar electrode.

In such an electrode structure, the bus bar electrode and the tab wire have a width of about 0.8 to 2 mm, and the distance between adjacent bus bar electrodes is generally set to about 30 to 80 mm. For example, in a solar cell using a 6-inch substrate, about 2 to 4 bus bars and tab wires are provided. The interconnection method in which the tab wire is connected to the bus bar electrode has problems that the cost of the metal electrode material is high and the shadowing loss due to the metal electrode and the tab wire is large. On the other hand, in the tab wire method, if the electrode width is reduced in order to reduce the electrode material cost and the shadowing loss, the line resistance and the contact resistance are increased, and the conversion characteristics are deteriorated.

As an interconnection method for solar cells, a method (multi-wire bonding) has been proposed in which a wire-shaped wiring material having a width narrower than that of a conventional tab wire is directly connected to a finger electrode without using a bus bar electrode. For example, Patent Document 1 discloses a solar cell module in which wire-shaped wiring materials are connected at intervals of 5 to 15 mm so as to be orthogonal to the finger electrodes.

In multi-wire bonding, the amount of current per wire is small, so even if the cross-sectional area of the wiring material is small, the electrical loss is small. Further, since the distance between the wires arranged adjacent to each other is small, the effective length of the finger electrodes (distance to the nearest wiring material) is short, and the number of finger electrodes and the line width can be reduced. As described above, the multi-wire bonding method does not require a bus bar electrode, and the number of finger electrodes and the line width are smaller than those of the tab wire method, so that the amount of electrode material used such as metal paste can be reduced. Further, the solar cell module by multi-wire bonding has a high design because the width of the wiring material is smaller than that of the tab wire method, so that the electrodes are hard to see.

Japanese Unexamined Patent Publication No. 2014-146697

Since the amount of current flowing through one wiring material is small in the multi-wire bonding method, electrical loss due to line resistance can be reduced as compared with the tab wire method. On the other hand, since the contact area between the electrode provided on the surface of the solar cell and the wiring material is small, the electrical loss due to the contact resistance tends to be large. Further, even in the multi-wire bonding method, the problem of deterioration of the design due to the visibility of the wiring material still remains. In particular, as in the case of the building material integrated module, the color and color tone are uniform with those around the module installation location. In applications that require, further improvement in design is required.

In view of the above, an object of the present invention is to provide a solar cell module having a small contact resistance between an electrode provided on the surface of a solar cell and a wiring material and having a high design in which the wiring material is hard to see.

The solar cell module of the present invention is a solar cell string in which a plurality of solar cells arranged apart from each other are connected via a wiring material, and a light-transmitting light-transmitting surface protection arranged on the light-receiving surface side of the solar cell string. It includes a material, a back surface protective material arranged on the back surface side of the solar cell string, and a sealing material for sealing the solar cell string between the light receiving surface protective material and the back surface protective material. The solar cell has a photoelectric conversion unit, a plurality of finger electrodes provided on the light receiving surface of the photoelectric conversion unit, and a back metal electrode provided on the back surface of the photoelectric conversion unit. The solar cell does not have an electrode (bus bar electrode) that is connected across a plurality of finger electrodes to the light receiving surface of the photoelectric conversion unit.

The wiring material connecting the adjacent solar cells has a triangular prism shape (triangular cross section) having a first side surface, a second side surface, and a third side surface, and the first side surface of the wiring material is provided on the light receiving surface of the solar cell. The finger electrode on the light receiving surface and the wiring material are connected so as to be in contact with the finger electrode. In the wiring material, the angle formed by the first side surface and the second side surface and the angle formed by the first side surface and the third side surface are both 41 to 70 °. The cross-sectional shape of the wiring material is preferably an isosceles triangle shape, and particularly preferably a regular triangle shape. The width of the wiring material (width of the first side surface) is preferably 0.1 to 0.7 mm.

The wiring material is twisted at a place not connected to the electrodes between the solar cells, and is wired with the back metal electrode so that the first side surface, the second side surface, or the third side surface of the wiring material is in contact with the back metal electrode. It is preferable that the material is connected. The wiring material preferably has a twisted portion at the end of the back surface of the solar cell. The twist angle of the wiring material is preferably less than 90 °. In this case, it is preferable that the back surface metal electrode and the wiring material are connected so that the second side surface or the third side surface of the wiring material is in contact with the back surface metal electrode.

In the solar cell module of the present invention, a contact area between the electrode and the wiring material can be secured by connecting adjacent cells using a triangular prism-shaped wiring material. Further, since the reflected light of the light that has reached the wiring material is not emitted to the outside of the module but is incident on the cell, the light utilization efficiency is excellent. Furthermore, since the wiring material is difficult to see from the outside, the design of the module is excellent.

It is a schematic sectional view of the solar cell module of one embodiment. It is a top view of the solar cell string seen from the light receiving surface side. It is a top view of the solar cell string seen from the back side. It is a schematic sectional view of the solar cell to which the wiring material is connected. It is a schematic sectional view of the solar cell to which the wiring material is connected. It is a schematic sectional view of the solar cell of one embodiment. It is a perspective view of a wiring material. It is sectional drawing of the wiring material. It is a conceptual diagram which shows the state of reflection of the light incident from the light receiving surface in the wiring material in the conventional solar cell module which used the wiring material with a circular cross section. It is a conceptual diagram which shows the state of the reflection of the light incident from the light receiving surface in the wiring material in the solar cell module using the wiring material of the triangular prism shape with a small inclination angle. It is a conceptual diagram which shows the state of the reflection of the light incident from the light receiving surface in the wiring material in the solar cell module using the wiring material of the triangular prism shape with a small inclination angle. It is a conceptual diagram which shows the state of reflection of the light incident from the light receiving surface in the wiring material in the solar cell module which used the wiring material of the triangular prism shape with a large inclination angle. It is a conceptual diagram which shows the state of the reflection of the light incident from the light receiving surface in the solar cell module using the triangular prism shape wiring material which the inclination angle is 65.5 °.

FIG. 1 is a schematic cross-sectional view of a solar cell module (hereinafter referred to as “module”). The module 200 includes a plurality of solar cells 100 (hereinafter, referred to as “cells”). The cell 100 includes metal electrodes 60 and 70 on the light receiving surface and the back surface of the photoelectric conversion unit 50, respectively. The metal electrodes 60 and 70 on the front and back surfaces of adjacent cells are connected via a wiring material 80, and a plurality of cells form a solar cell string electrically connected.

A light receiving surface protective material 91 is provided on the light receiving surface side (upper side of FIG. 1) of the solar cell string, and a back surface protective material 92 is provided on the back surface side (lower side of FIG. 1). In the module 200, the solar cell string is sealed by filling the sealing material 95 between the protective materials 91 and 92.

2A and 2B are plan views of a solar cell string in which a plurality of cells 100 are connected via a wiring material 80, FIG. 2A is a plan view of a light receiving surface, and FIG. 2B is a plan view of a back surface. 3A and 3B are schematic cross-sectional views of the cell 100 to which the wiring material 80 is connected, FIG. 3A is a cross section orthogonal to the extending direction of the wiring material, and FIG. 3B is parallel to the extending direction of the wiring material. Represents a cross section.

The light receiving surface metal electrode 60 of the cell 100 is composed of a plurality of finger electrodes 61 extending in one direction (y direction). The plurality of finger electrodes 61 are arranged apart from each other in a direction (x direction) orthogonal to the extending direction. The light receiving surface metal electrode does not have an electrode (so-called bus bar electrode) that is connected across the finger electrodes, and the plurality of finger electrodes are electrically separated from each other in the wiring material and the cell before connection. The back surface metal electrode 70 may be composed of a plurality of finger electrodes 71 like the light receiving surface metal electrode, or may be a planar metal electrode provided on the entire surface of the photoelectric conversion unit.

On the light receiving surface, the wiring material 80 is provided on the finger electrode 61, and the extending direction (x direction) of the wiring material and the extending direction (y direction) of the finger electrode are orthogonal to each other.

As the cell 100, a type in which the solar cells are interconnected by a wiring material, such as a crystalline silicon solar cell or a solar cell provided with a semiconductor substrate other than silicon such as GaAs, is used. FIG. 4 is a schematic cross-sectional view showing one form of the cell 100. The photoelectric conversion unit 50 includes a crystal semiconductor substrate 1. The crystalline semiconductor substrate may be single crystal or polycrystalline, and a single crystal silicon substrate, a polycrystalline silicon substrate, or the like is used. It is preferable that the surface of the crystalline semiconductor substrate 1 on the light receiving surface side is formed with irregularities having a height of about 1 to 10 μm. By forming irregularities on the light receiving surface, the light receiving area is increased and the reflectance is reduced, so that the light confinement efficiency is improved. The back surface side of the substrate may also be provided with irregularities.

The cell 100 shown in FIG. 4 is a so-called heterojunction cell, and the intrinsic amorphous silicon thin film 21, the p-type amorphous silicon thin film 31, and the transparent conductive film 41 are placed on the light receiving surface side of the n-type single crystal silicon substrate 1. In this order, the intrinsic amorphous silicon thin film 22, the n-type amorphous silicon thin film 32, and the transparent conductive film 42 are provided on the back surface side in this order. A light receiving surface metal electrode 60 (light receiving surface finger electrode 61) is provided on the transparent conductive film 41, and a back surface metal electrode 70 (back surface finger electrode 71) is provided on the transparent conductive film 42.

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

The thickness of the sealing material on the light receiving surface side, that is, the distance D from the light receiving surface of the cell 100 to the light receiving surface protective material 91 is generally about 0.2 to 1.2 mm, and 0.3 to 1.1 mm. Is preferable, and 0.4 to 1.0 mm is more preferable. Further, the thickness of the sealing material on the light receiving surface side is preferably larger than the height H of the wiring material. By setting the thickness of the sealing material within the above range, it is possible to reliably seal the uneven portion provided with the electrode and the wiring material, and the light absorption by the sealing material is small.

The light receiving surface protective material 91 is light transmissive, and glass, transparent plastic, or the like is used. The back surface protective material 92 may be light-transmitting, light-absorbing, or light-reflecting. As the light-reflecting back surface protective material, a material having a metallic color or white color or the like is preferable, and a white resin film, a laminate in which a metal foil such as aluminum is sandwiched between resin films, or the like is preferably used.

As the light-absorbing protective material, for example, a material containing a black resin layer is used. The black resin layer is visible light absorptive and mainly absorbs visible light having a wavelength of 800 nm or less. The visible light transmittance of the black resin layer is preferably 10% or less. As the black resin layer, a resin composition containing a thermoplastic resin such as a polyolefin resin, a polyester resin, an acrylic resin, a fluororesin, an ethylene / vinyl acetate resin, and a colorant such as a pigment or a dye is preferably used. In order to laminate the black resin layer and the infrared reflective layer to give the back surface protective material infrared reflectivity, the colorant is preferably a material that absorbs visible light and transmits near infrared rays, and has different hues from each other. A combination of three or more kinds of colorants having a lightness of L ^* 45 or more, a dark-colored organic pigment, or the like is used. The black resin layer may contain an inorganic pigment having infrared reflectivity.

When the back surface protective material containing the black resin layer is used, since the appearance colors of the back surface protective material and the cells are close to each other, the gaps between the cells arranged apart from each other are not conspicuous, and a module with high design can be obtained. As will be described in detail later, in the present invention, by using the wiring material having a predetermined shape, the reflected light from the wiring material is not emitted to the outside from the light receiving surface side of the module, so that the metallic color of the wiring material is hardly visible. Therefore, by using a light-absorbing back surface protective material, it is possible to obtain a highly-designed module that is entirely black.

As the light-absorbing protective material, a material in which a black resin layer and an infrared reflective layer are laminated in order from the cell 100 side may be used. By arranging the infrared reflective layer on the back surface side of the black resin layer, the near infrared rays transmitted to the back surface side without being absorbed by the photoelectric conversion unit and the light incident on the gap between the cells are reflected and re-entered into the cell. It is possible to improve the light utilization efficiency and the module conversion efficiency.

The infrared reflecting layer preferably has a reflectance of near-infrared light having a wavelength of 800 nm to 1200 nm of 80% or more, more preferably 85% or more, and further preferably 90% or more. In order to re-infrared the near infrared rays reflected by the infrared reflecting layer into the cell, the black resin layer preferably has a transmittance of near infrared light having a wavelength of 800 nm to 1200 nm of 80% or more.

As the infrared reflective layer, a resin layer made of a resin composition containing a white pigment having infrared reflectivity such as titanium oxide, an infrared reflective metal foil (for example, aluminum, silver) and the like are used. The metal leaf may cause corrosion, short circuit, etc. due to contact with air. Therefore, from the viewpoint of improving the reliability and safety of the module, a resin layer containing no metal foil is preferably used as the infrared reflecting layer. An adhesive layer or the like for bonding the black resin layer and the infrared reflecting layer may be included between the black resin layer and the infrared reflecting layer.

<Wiring material>
FIG. 5A is a perspective view of the wiring material 80 used for electrically connecting a plurality of cells, and FIG. 5B is a cross-sectional view taken along the line B1-B2. The wiring material 80 has a triangular prism shape and has a first side surface 81, a second side surface 82, and a third side surface 83 parallel to the extending direction. The cross section of the wiring material 80 orthogonal to the extending direction is triangular. The cross-sectional shape of the wiring material 80 is not limited to a strict triangle, and the top may be rounded, for example.

In the module, the first side surface 81 is connected to the light receiving surface finger electrode 61 of the cell. The angle θ ₁ formed by the first side surface 81 and the second side surface 82 and the angle θ ₂ formed by the first side surface 81 and the third side surface 83 are both 41 to 70 °. When all three angles of the triangle in the cross section are 41 to 70 °, any side surface may be used as a connecting surface with the light receiving surface finger electrode.

The width W of the first side surface 81 (hereinafter, may be referred to as the bottom surface) of the wiring material 80 is equal to the width of the wiring material when the module is viewed from the light receiving surface side. The width and number of wiring materials may be set so that the current loss due to the resistance of the wiring material is sufficiently small according to the size (area) of the cell, the number of wiring materials connected to one cell, and the like. .. For example, in a cell using a 6-inch substrate (length of one side 156 mm), it is preferable to connect about 5 to 20 wiring materials to one cell. The width W of the wiring material is preferably in the range of 0.1 to 0.7 mm. The distance between the wiring materials arranged adjacent to each other on the cell is preferably about 5 to 25 mm, more preferably 7 to 20 mm.

In order to reduce the current loss caused by the resistance of the wiring material, the material of the wiring material 80 preferably has a low resistivity. Among them, a metal material containing copper as a main component is particularly preferable because of its low cost. By reflecting the light on the surface of the wiring material and causing the reflected light to enter the photoelectric conversion unit, the shadowing loss due to the wiring material can be reduced. Therefore, the surface of the wiring material preferably has a high reflectance. In order to increase the reflectance of the surface, the wiring material 80 may use a core material such as copper whose surface is coated with a high reflectance material such as gold, silver or aluminum. The thickness of the high reflectance material that covers the surface of the core material is preferably, for example, about 0.5 to 3 μm.

Hereinafter, the light utilization efficiency and design of the module of the present invention will be described from the viewpoint of light reflection in the wiring material.

FIG. 6 is a conceptual diagram showing a state of light reflection by the wiring material in a conventional solar cell module using a wire 89 having a circular cross section as a wiring material. The light that has passed through the light receiving surface protective material 91 and the sealing material 95 and reached the wiring material 89 having a circular cross section is reflected at various angles depending on the incident angle and the arrival position on the wiring material.

For example, the oblique incident light L ₉₅ in FIG. 6 is reflected by the wiring material 89, and the reflected light L ₉₆ reaches the interface between the light receiving surface protective material 91 and air at an incident angle θ _r . When glass (refractive index of about 1.5) is used as the light receiving surface protective material, the critical angle is about 41 °. Therefore, when the incident angle θ _r is 41 ° or more, the reflected light L ₉₆ is totally reflected at the interface between the light receiving surface protective material and the air, and the rereflected light L ₉₇ is incident on the photoelectric conversion unit 50 of the cell and is light. Contributes to carrier generation.

On the other hand, when the angle of incidence θ _r of the reflected light of the wiring material 89 on the interface between the light receiving surface protective material and air is less than 41 °, some light is not reflected at the interface between the light receiving surface protective material and air. In addition, it is ejected from the surface of the light receiving surface protective material 91 to the outside of the module. For example, the light L _{91 that} is incident on the vicinity of the apex of the wire at a small angle is partly because the angle of incidence of the reflected light L _{92 on} the wiring material on the interface between the light receiving surface protective material 91 and the air is smaller than the critical angle. Is not reflected, and the emission light L ₉₃ is emitted to the outside of the module. The reflected light emitted to the outside of the module causes shadowing loss due to the wiring material and does not contribute to power generation, which causes a decrease in module conversion efficiency. Further, since the emitted light L ₉₃ is visually recognized as reflected light of the wiring material from the outside of the module, the metallic color of the wiring material is visually recognized, which causes a deterioration in the design of the module.

7A and 7B show the reflection of light incident on the module from the light receiving surface when a triangular columnar wiring material 88 having an angle θ formed by the bottom surface and the side surface of less than 41 ° (for example, about 30 °) is used. It is a conceptual diagram showing.

In FIG. 7A, the light L ₁₀ that has passed through the protective material 91 and the sealing material 95 and reached the wiring material 88 from the front surface of the light receiving surface of the module is reflected by the side surface of the wiring material 88. The reflected light L ₁₁ reaches the interface between the light receiving surface protective material 91 and air at an incident angle θ _r . Since θ _r = 2θ, if the inclination angle θ of the wiring material is 20.5 ° or more, θ _r becomes larger than the critical angle, and the reflected light L ₁₁ is totally at the interface between the light receiving surface protective material and the air. The reflected and re-reflected light L ₁₂ enters the photoelectric conversion unit 50 of the cell and contributes to the generation of optical carriers.

On the other hand, as shown in FIG. 7B, when the incident angle of the incident light L ₂₀ is large and the refraction angle γ is large, it reaches the interface between the light receiving surface protective material 91 of the reflected light L ₂₁ reflected on the side surface of the wiring material and the air. The incident angle θ _{r of} is smaller than the critical angle. Therefore, a part of the reflected light L ₂₁ is emitted to the outside of the module as the emitted light L ₂₃ , which causes a decrease in light utilization efficiency and a decrease in design.

FIG. 8 is a concept showing the state of reflection of light incident on the module from the light receiving surface when a triangular columnar wiring material 85 having an angle θ formed by the bottom surface and the side surface of 41 ° or more (for example, about 60 °) is used. It is a figure. The light L ₃₀ that has passed through the protective material 91 and the sealing material 95 and reached the wiring material 88 at a small incident angle (and refraction angle) is reflected on the side surface of the wiring material 85, and the reflected light L ₃₁ is reflected on the light receiving surface side. It is incident on the photoelectric conversion unit 50 of the cell as it is without being performed. The incident light L ₄₀ having a refraction angle γ close to the critical angle is reflected on the side surface of the wiring material 85 toward the light receiving surface side. The angle of incidence θ _r of the reflected light L ₄₁ at the interface between the light receiving surface protective material 91 and air is larger than the inclination angle θ _r of the wiring material. Therefore, if the inclination angle θ 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 protective material and the air, and the rereflected light L ₄₂ is incident on the photoelectric conversion unit 50 of the cell. Contributes to the generation of optical carriers.

As described above, when the angle θ formed by the bottom surface and the side surface of the wiring material is equal to or greater than the critical angle (41 °) at the interface between the air and the light receiving surface protective layer 91, the surface reaches the side surface of the wiring material and is reflected. The light is totally reflected directly or at the interface between the light receiving surface protective material and air, and then enters the photoelectric conversion unit 50 and is not emitted to the outside of the module. Therefore, the shadowing loss due to the wiring material is substantially zero, and a module with high light utilization efficiency can be obtained. Further, since the reflected light from the wiring material is not emitted to the outside of the module, the reflected light from the wiring material is not visible from the outside of the module, and the wiring material looks black. Therefore, the color of the wiring material and the color of the surrounding cells are unified in black, and the design is enhanced.

In the module of the present invention, since the angles θ ₁ and θ ₂ formed by the bottom surface and the side surface of the triangular columnar wiring material 80 are both 41 ° or more, wiring can be performed with respect to light incident on the module from any direction. The reflected light from the material is not emitted to the outside of the module. Therefore, the module of the present invention is excellent in conversion efficiency and design.

FIG. 9 is a conceptual diagram showing the state of reflection of light incident on the module from the light receiving surface when the triangular columnar wiring material 86 having an angle θ formed by the bottom surface and the side surface is 65.5 ° is used. Regardless of whether the refraction angle γ of the incident light L ₅₀ is 0 to 41 °, the reflected light L ₅₁ reflected on the side surface of the wiring material 86 is not reflected on the light receiving surface side, and is directly reflected in the photoelectric conversion unit 50 of the cell. Incident in. That is, when the angle θ between the bottom surface and the side surface of the wiring material is 65.5 ° or more, the light that reaches the side surface of the wiring material is not reflected to the light receiving surface side, and all the reflected light is directly. It is incident on the photoelectric conversion unit 50. Therefore, the amount of light absorbed and scattered when passing through the sealing material 95 and the like after being reflected by the wiring material is small, and the light utilization efficiency and designability of the module are further improved.

If the angle θ formed by the bottom surface and the side surface of the wiring material exceeds 65.5 °, improvement in light utilization efficiency and designability cannot be expected even if θ becomes larger than that. On the other hand, if the angle θ formed by the bottom surface and the side surface of the wiring material is excessively large, the height H of the wiring material increases and the apex angle decreases, so that the sealing material 95 can be used for reliable sealing. It is necessary to increase the thickness of the sealing material on the light receiving surface side. In addition to being a cost-increasing factor, the increase in the thickness of the encapsulant tends to increase the light absorption by the encapsulant and reduce the conversion efficiency. Therefore, the angle formed by the bottom surface and the side surface of the wiring material is preferably 70 ° or less.

<Modularization>
A solar cell string is produced by interconnecting adjacent cells via a wiring material 80. By arranging and laminating the sealing material and the protective material on the light receiving surface side and the back surface side of the solar cell string and heat-pressing them, the sealing material flows between the cells and at the end of the module. Modularization is done.

The wiring material and the finger electrode are connected so that the bottom surface 81 of the wiring material 80 and the finger electrode 61 face each other. Since the wiring material 80 is in surface contact with the finger electrode, the contact area with the finger electrode is larger than that of the wiring material having a circular cross section. Therefore, the module of the present invention has a smaller contact resistance and higher reliability of connection between the cell and the wiring material than the module using the wiring material having a circular cross section.

Examples of the method of connecting the wiring material and the finger electrode include a method of using a conductive paste (CP) and a conductive film (CF), a method of joining by soldering, a method of using a transparent resin adhesive, and the like. As the transparent resin adhesive, for example, acrylic resin, epoxy resin, imide resin, phenol resin and the like are used. Examples of the connection using the transparent resin adhesive include a method in which the wiring material 80 is placed on the finger electrode 61 and then the adhesive is applied so as to cover the wiring material. Further, an adhesive layer may be provided on the bottom surface 81 of the wiring material 80, and the finger electrode and the wiring material may be connected by thermocompression bonding.

When the wiring material 80 has an isosceles right triangle cross section, that is, when θ ₁ = θ ₂ , it is not necessary to confirm the orientation of the wiring material at the time of connection, so that productivity can be improved. In particular, when the wiring material 80 has a regular triangular cross section, any surface of the wiring material may be connected to the finger electrode. Therefore, from the viewpoint of module productivity, it is particularly preferable that the wiring material 80 has a regular triangular cross section. The two base angles θ ₁ and θ ₂ in the isosceles triangle do not have to be exactly the same, and may have a difference of about ± 2 °. Further, the three internal angles of the equilateral triangle do not have to be exactly 60 °, and may have an error of about ± 2 °. That is, if all three internal angles are within the range of 58 to 62 °, it may be regarded as an equilateral triangle.

When the bottom surface 81 of the wiring material 80 is connected to the finger electrode 61 on the light receiving surface side, when the wiring material is wrapped around the back surface side of the adjacent cell, the top of the wiring material 80 (the corner where the side surface 82 and the side surface 83 intersect). However, the arrangement is such that the back surface finger electrode 71 is opposed to the back surface finger electrode 71. When the top of the wiring material is connected to the finger electrode, the contact area is small, which makes it difficult to take out the current and causes a problem in the reliability of the connection. Therefore, it is preferable to twist the wiring material in order to connect the side surface of the triangular prism-shaped wiring material 80 and the electrode on both the light receiving surface of the cell and the back surface of the adjacent cell.

The wiring material is twisted at a place not connected to the electrode between the solar cells, such as a gap between cells, near the end of the light receiving surface, and near the end of the back surface. In the twisted portion 801 in which the wiring material is twisted, the angle formed by the side surface of the wiring material and the light receiving surface of the cell is different from that of the connection portion with the finger electrode. Therefore, when the light from the light receiving surface reaches the twisted portion of the wiring material, a part of the reflected light is emitted from the light receiving surface of the module, and the metallic color of the twisted portion of the wiring material is visually recognized from the outside. When the twisted portion is visually recognized from the outside, the design of the module is deteriorated. In particular, when a light-absorbing back surface reflector is used, the reflected light at the twisted portion is easily noticeable because the entire module is unified in black. In order to prevent the reflected light from the twisted portion from being visually recognized from the outside, as shown in FIGS. 1, 2B and 3B, the twisted portion 801 of the wiring material is provided near the end portion on the back surface of the cell. Is preferable.

The twist angle of the wiring material 80 is not particularly limited as long as the side surface of the wiring material and the electrode can be connected to both the light receiving surface and the back surface of the cell. The twist angle is preferably as small as possible in order to reduce the length of the twisted portion 801 in the extending direction of the wiring material and prevent the wiring material from being visually recognized from the outside. Further, it is preferable that the twisting angle is small from the viewpoint of suppressing connection failure due to stress caused by twisting of the wiring material. Therefore, the twist angle is preferably less than 90 °, more preferably 80 ° or less, and even more preferably 70 ° or less.

In order to connect one side surface of the wiring material to the electrode on the light receiving surface of the cell and the electrode on the back surface side of the cell, the twist angle of the wiring material needs to be 180 °. Therefore, it is preferable that the side surface of the wiring material connected to the electrode on the light receiving surface and the side surface of the wiring material connected to the back surface are different surfaces. For example, when the first side surface 81 of the wiring material 80 is connected to the electrode on the light receiving surface, it is preferable that the second side surface 82 or the third side surface 83 is connected to the electrode on the back surface of the adjacent cell.

200 Solar cell module 100 Solar cell 50 Photoelectric conversion part 1 Crystal semiconductor substrate 60 Light-receiving surface electrode 70 Back electrode 61, 71 Finger electrode 80 Wiring material 91 Light-receiving surface protection material 92 Back surface protection material 95 Encapsulant

Claims (5)

A solar cell string in which a plurality of solar cells arranged apart from each other are connected via a wiring material; a light-transmitting light-transmitting surface protective material arranged on the light-receiving surface side of the solar cell string; A solar cell module comprising a back surface protective material arranged on the back surface side; and a sealing material for sealing the solar cell string between the light receiving surface protective material and the back surface protective material.
The solar cell has a photoelectric conversion unit, a plurality of finger electrodes provided on the light receiving surface of the photoelectric conversion unit, and a back metal electrode provided on the back surface of the photoelectric conversion unit.
The light receiving surface of the photoelectric conversion unit is not provided with electrodes that are connected across the plurality of finger electrodes.
The wiring material has a triangular prism shape having a first side surface, a second side surface, and a third side surface.
The angle between the first side surface and the second side surface and the angle between the first side surface and the third side surface are both 41 to 70 °.
The width of the first side surface is 0.1 to 0.7 mm,
Wiring member for connecting the second solar cell adjacent to the first solar cell and the first solar cell, a first side surface of the wiring member is contact with the finger electrode provided on the light receiving surface of the first solar cell, A portion where the first side surface, the second side surface or the third side surface of the wiring material is connected so as to be in contact with the metal electrode on the back surface of the second solar cell, and is not connected to the electrodes of the first solar cell and the second solar cell. A solar cell module having a fertile portion in which the wiring material is twisted . The wiring member includes the twisting portion at the end portion of the rear surface of the second solar cell, the solar cell module according to claim 1. The back surface metal electrode and the wiring material are connected so that the twist angle of the twisted portion of the wiring material is less than 90 ° and the second side surface or the third side surface of the wiring material is in contact with the back surface metal electrode. The solar cell module according to claim 1 or 2 . The solar cell module according to any one of claims 1 to 3 , wherein the wiring material has an isosceles right triangle cross section. The solar cell module according to any one of claims 1 to 3 , wherein the wiring material has a regular triangular cross section.

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