JP7702844B2 - Solar Cell Module - Google Patents

Description

The present invention relates to a solar cell module having multiple solar cells.

Generally, solar cell modules are often installed outdoors. Therefore, in order to obtain sufficient weather resistance and strength, the solar cell is sealed with a sealant and a front protective member and a back protective member are provided. In addition, to extract the electricity generated by photoelectric conversion in the solar cell, output wiring is electrically connected to the electrode part of the solar cell. The output wiring is pulled out to the back side of the solar cell module and connected to the connection terminal of the terminal box.

In this type of solar cell module, the back surface protection member is a laminated film with a multi-layer structure in which a metal foil such as aluminum is sandwiched in order to improve the weather resistance and moisture resistance of the solar cell module. For example, Patent Document 1 discloses the use of a fluorine-based resin sheet or a polyethylene terephthalate (PET) sheet vapor-deposited with alumina or silica as the back surface protection member.

In addition, the sealing material arranged on the light-receiving surface and back surface is often made of ethylene-vinyl acetate copolymer (ethylene vinyl acetate, hereafter referred to as EVA), a thermally crosslinkable transparent resin, which has properties such as light transmissivity, heat resistance, and electrical insulation.

JP 2014-229754 A

However, because the use of a back surface protective member containing metal foil can cause insulation problems, in recent years, PET film that does not contain metal foil is sometimes used as the back surface protective member. The output wiring is pulled out to the back side of the solar cell module by penetrating the back surface protective member in order to connect to the connection terminal of the terminal box. This can lead to the risk of moisture such as water vapor penetrating through the back surface protective member around the terminal box.

In addition, the EVA, polyolefin, and PVB (polyvinyl butyral) used in the sealing materials have the property of easily releasing acetic acid when they come into contact with moisture. EVA in particular releases a large amount of acetic acid. There is a risk that the free acid will corrode the metal electrodes and reduce the adhesion between the metal electrodes and the sealing material. Therefore, there was a need to create a structure that is more moisture-resistant by suppressing the effects of moisture penetration from the back side of the solar cell module.

The present invention was made in consideration of the above-mentioned problems, and its purpose is to provide a solar cell module that can prevent moisture from entering from the back side opposite the light-receiving surface, thereby improving moisture resistance and long-term reliability.

The solution of the present invention to achieve the above object is a solar cell module in which a plurality of electrically connected solar cells are sealed with a sealing material between a light-transmitting substrate and a back surface protection member, and an intermediate sheet member having a moisture-proofing property more than the sealing material is provided between the solar cells and the back surface protection member, and the module has a layered structure in which the light-transmitting substrate, the sealing material, the solar cells, the sealing material, the intermediate sheet member, the sealing material, and the back surface protection member are arranged in this order from the light-receiving surface side.

In addition, in a solar cell module having the above configuration, an output section that outputs the power generated in the solar cell to the outside is provided on the back surface of the back surface protection member, which is the surface opposite to the light receiving surface side, and the output section is preferably disposed on the back surface side of the back surface protection member in the laminated structure.

In addition, in a solar cell module having the above configuration, it is preferable that the intermediate sheet member is provided in an area that includes at least the light receiving surface side of the output section.

In addition, in a solar cell module having the above configuration, the intermediate sheet member may be provided in the entire area between the solar cell and the back surface protection member.

In addition, in a solar cell module having the above configuration, the intermediate sheet member and the back surface protection member may be made of a common sheet-like member.

Furthermore, in a solar cell module having the above configuration, it is preferable that the intermediate sheet member comprises a resin sheet containing either PTFE, ETFE or PET.

In addition, in a solar cell module having the above configuration, it is preferable that the intermediate sheet member includes a reflective layer that reflects light in the wavelength range of 700 nm or more.

By satisfying these specific requirements, the intermediate sheet member in the laminated structure acts to prevent moisture from penetrating from the back side opposite the light-receiving surface, thereby improving moisture resistance.

The present invention makes it possible to prevent moisture from entering from the back side opposite the light receiving surface, further improving moisture resistance and resulting in a solar cell module with high long-term reliability.

1 is a plan view showing a schematic configuration of a solar cell module according to a first embodiment of the present invention. 4 is a cross-sectional view showing a connection structure between solar cells in the solar cell module. FIG. 4 is a cross-sectional view illustrating an example of an intermediate sheet member provided in the solar cell module. FIG. 6 is a cross-sectional view showing a schematic diagram of another example of an intermediate sheet member provided in the solar cell module. FIG. FIG. 11 is a plan view showing a schematic configuration of a solar cell module according to a second embodiment of the present invention. 4 is a cross-sectional view showing an example of a lamination form of intermediate sheet members in the solar cell module. FIG.

The solar cell module according to an embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a plan view showing a schematic configuration of a solar cell module 1 according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the internal structure of the solar cell module 1, showing the connection structure of solar cells 10.

In FIG. 1, the components of the solar cell module 1, such as the sealing material and back surface protection member, are omitted. In addition, the components common to the first and second embodiments described below are indicated by the same reference numerals, and duplicate descriptions of those components are omitted.

As shown in FIG. 1, the solar cell module 1 includes a panel 40 including a solar cell string 21 formed by electrically connecting a plurality of solar cells 10, and a plurality of wiring members (32, 33) that electrically connect the solar cell string 21. A frame (not shown) is attached to the outer periphery of the panel 40.

As shown in FIG. 2, the solar cell module 1 has a structure in which a number of solar cells 10, etc., arranged in a first direction D1, are sealed with a sealant 43 between a light-transmitting substrate 41 and a back surface protection member 42. The light-transmitting substrate 41 is provided on the light-receiving surface side of the solar cell module 1 (the upper side in FIG. 2), and the back surface protection member 42 is provided on its back surface. Here, the "light-receiving surface" of the solar cell module 1 refers to the surface onto which sunlight is mainly incident, and the "back surface" refers to the surface opposite the light-receiving surface side.

The solar cell 10 is a flat photovoltaic element that generates electric power when irradiated with light, and as shown in FIG. 2, has a surface electrode 101 and a back electrode 102. For example, the surface electrode 101 has a busbar electrode 103 and finger electrodes (not shown). The busbar electrode 103 is strip-shaped and is formed linearly in a first direction D1 on the surface of the solar cell 10. The finger electrodes are formed extending from both side edges of the busbar electrode 103 in a second direction D2. The finger electrodes are patterned at regular intervals from each other to cover the entire light receiving surface of the solar cell 10.

The back electrode 102 is formed in a linear strip shape in the first direction D1 on the back surface of the solar cell 10, and is provided facing the bus bar electrode 103. The wiring material (interconnector) 31 is connected to the bus bar electrode 103 of the front electrode 101 of one solar cell 10 and the back electrode 102 of the other solar cell 10, connecting adjacent solar cells 10 in series.

The wiring material 31 is configured by coating the outer surface of a substrate formed in a long, thin strip shape or a wire with a roughly circular cross section with a conductive adhesive or solder. There are no particular limitations on the material of the substrate and wire, but metals such as copper can be used.

The solar cell 10 connected in this manner each has a flat plate shape, and in the embodiment shown in FIG. 1, for example, a split cell is used in which a solar cell substrate measuring approximately 156 mm square is split into two. Therefore, the solar cell 10 has a size of approximately 156 mm x 78 mm square.

Here, a divided cell refers to a small cell that is divided from a standard-sized cell (a cell equivalent to one solar cell wafer, also called a full cell). Examples of divided cells include a standard-sized cell divided in half (half cell), one-third or one-quarter, etc. With divided cells, the current value per cell can be reduced (halved in the case of a half cell), which makes it possible to reduce the power loss of the solar cell module 1 accordingly. In the illustrated embodiment, the solar cell 10 is a half cell.

In the solar cell module 1, a plurality of half-cell solar cells 10 are arranged in a matrix along a first direction (column direction) D1 and a second direction (row direction) D2. In the solar cell module 1 according to the exemplary embodiment, as shown in FIG. 1, wiring members (end wiring members 32, intermediate wiring members 33) are provided in the middle of the first direction D1 of the panel 40. On both sides of the first direction D1, 12 solar cells 10 are arranged along the first direction D1, sandwiching these wiring members, and are electrically connected in series by the wiring members 31 described above to provide a solar cell string 21. In addition, in the second direction D2, a plurality of solar cell strings 21 including 12 solar cells are arranged adjacent to each other, and the solar cell strings 21 are electrically connected in series via the intermediate wiring members 33.

The solar cell strings 21 arranged at both ends in the second direction D2 are electrically connected to the end wiring member 32 at one end in the first direction D1, and are electrically connected to adjacent solar cell strings 21 at the other end by an intermediate wiring member 33. Six solar cell strings 21 are arranged along the second direction D2 on both sides of the wiring members 32, 33, forming a solar cell group 20 in which a total of 72 solar cell cells 10 are arranged in a 12 x 6 arrangement. The end wiring member 32 has the role of extracting power from the multiple solar cell strings.

As a result, the solar cell module 1 includes two solar cell groups 20 in which 72 solar cells 10 are connected in series within the panel 40, and these solar cell groups 20 are electrically connected in parallel. Therefore, the solar cell module 1 in the illustrated embodiment is capable of outputting power equivalent to 72 full cells connected in series (equivalent to 72 half cells x 2).

In such a solar cell module 1, a moisture-proof intermediate sheet member 44 is provided between the solar cell 10 and the back surface protection member 42 as a structure to enhance moisture resistance.

Referring to FIG. 2, the solar cell module 1 has a laminated structure in which, from the light-receiving surface side, a translucent substrate 41, a sealing material 43a (43) on the light-receiving surface side, a plurality of solar cells 10, a sealing material 43b (43) in the middle, an intermediate sheet member 44, a sealing material 43c (43) on the back surface side, and a back surface protection member 42 are arranged in this order. The sealing materials 43a, 43b, and 43c are all sealing materials 43 made of a common resin material whose main component is EVA.

The light-transmitting substrate 41 is disposed so as to face the front surface side of the solar cell 10 (the upper side in FIG. 2). Any substrate that is transparent to sunlight can be used as the light-transmitting substrate 41, without any particular limitations. For example, a glass substrate can be used.

The back surface protection member 42 is provided so as to face the back surface side of the solar cell 10 (the lower side in FIG. 2). Any material can be used as the back surface protection member 42 as long as it can protect the back surface side of the sealing material 43, and for example, a weather-resistant film such as PET can be used.

The intermediate sheet member 44 is a sheet-like member that is moisture-proof and infrared-reflective. FIG. 3 is a cross-sectional view showing an example of the intermediate sheet member 44. An example of the intermediate sheet member 44 applied to the solar cell module 1 is a sheet-like member with a multi-layer structure in which a black layer 441 and a reflective layer 442 are laminated.

The black layer 441 is a layer containing a base resin having a hydroxyl group, a curing agent having an isocyanate group, and a pigment component. This black layer 441 is a layer having the same color or a similar color tone as the solar cell 10. For example, the black layer 441 can be formed by applying or laminating a dark ink having the same color or a similar color tone as the solar cell 10 onto the reflective layer 442 and drying and curing it. The application method can be various application methods such as roll coating, gravure roll coating, kiss coating, or printing.

The reflective layer 442 is made of, for example, a resin sheet containing a white pigment or a resin sheet on which a coating layer (coating film or printing film) containing a white pigment is formed, and is a white resin layer that reflects light in the wavelength range of 700 nm or more. For example, the reflective layer 442 is configured to reflect light in the wavelength range of 700 nm or more that has passed through the black layer 441, more specifically, infrared light (near infrared light) in the wavelength range of 780 nm or more.

In addition, as the resin sheet constituting the reflective layer 442, for example, a resin sheet such as a fluororesin such as PTFE (polytetrafluoroethylene) or ETFE (ethylene tetrafluoride copolymer), a poly(meth)acrylic resin, or a polyester resin such as PET (polyethylene terephthalate) can be used. These resin sheets have a lower water vapor permeability than the sealing material 43. For example, the water vapor permeability of PET is 0.7 g mm/m ² d. This allows the intermediate sheet member 44 to be provided with moisture resistance. In addition, in order to reflect near infrared rays, the reflective layer 442 preferably contains a white pigment having a particle size of 0.1 μm or more and 1.5 μm or less at a predetermined ratio. An example of such a white pigment is titanium oxide.

The intermediate sheet member 44 is laminated in the solar cell module 1 in an orientation such that the black layer 441 faces the solar cell 10 side (light receiving surface side) and the reflective layer 442 faces the back surface protection member 42 side (back surface side). The intermediate sheet member 44, which includes a resin sheet with a lower water vapor permeability than the sealing material 43c, is provided between the sealing material 43b and the sealing material 43c, thereby preventing the intrusion of moisture from the sealing material 43c into the sealing material 43b. Therefore, the intermediate sheet member 44 is provided between the sealing material 43b and the sealing material 43c to prevent the intrusion of moisture from the back surface side to the light receiving surface side.

The solar cell module 1 is heated and pressed in this laminated structure, so that, as shown in FIG. 2, a sealant 43b is provided between the intermediate sheet member 44 and the back side of the solar cell 10, sealing the solar cell 10. The back side of the intermediate sheet member 44 also has a sealed structure with a sealant 43c provided between the back protection member 42.

The solar cell module 1 has the black layer 441 of the intermediate sheet member 44 disposed on the upper layer (light receiving surface side). As a result, incident light on the solar cell module 1 passes through the light-transmitting substrate 41 and the sealing material 43 to reach the solar cell 10, and some of the incident light reaches the intermediate sheet member 44 on the back side of the solar cell 10. In the intermediate sheet member 44, much of the infrared light contained in the incident light is reflected by the reflective layer 442. Due to the presence of the intermediate sheet member 44, most of the infrared light is reflected and not absorbed, so that the temperature rise of the solar cell module 1 due to infrared absorption can be suppressed.

The back surface of the solar cell module 1 is prevented from infiltrating by the back surface protection member 42, and further prevented from infiltrating by the intermediate sheet member 44, ensuring double moisture resistance. Even if a small amount of moisture does infiltrate, the intermediate sheet member 44 is provided on the inside of the back surface protection member 42 with the sealing material 43c interposed therebetween, so that the resin sheet constituting the reflective layer 442 of the intermediate sheet member 44 prevents moisture from infiltrating into the solar cell 10 side. This prevents moisture such as water vapor from the back surface side from reaching the sealing material 43b, suppresses the generation of free acid in the EVA, and makes it possible to maintain adhesion between the back electrode 102 of the solar cell 10 and the sealing material 43.

When the solar cell module 1 is viewed from the light-receiving surface side, the solar cell 10 and the intermediate sheet member 44 on the back surface side are visible through the translucent substrate 41 and the sealing material 43. The black layer 441 of the intermediate sheet member 44 is the same color or a similar color as the solar cell 10, so they appear integrated, improving the design.

Figure 4 is a cross-sectional view showing a schematic diagram of another example of the intermediate sheet member 44 applied to the solar cell module 1. The intermediate sheet member 44 may be a sheet-like member having a multi-layer structure including a transparent resin layer 443 in addition to a black layer 441 and a reflective layer 442. In this case, the transparent resin layer 443 is preferably a transparent or semi-transparent resin layer that improves adhesion with the EVA sealing material 43 and transmits visible light. For example, a polyolefin resin such as a polyethylene resin or a polypropylene resin, or polyethylene terephthalate (PET) can be used for the transparent resin layer 443.

The intermediate sheet member 44 configured in this manner can also suppress the infiltration of moisture from the back side of the solar cell module 1 and prevent it from reaching the sealing material 43b, thereby suppressing the generation of free acid in the EVA and making it possible to maintain adhesion between the back electrode 102 of the solar cell 10 and the sealing material 43.

In this embodiment, when a resin sheet including a color tone layer of the same color or similar color as the solar cell 10 is used for the back surface protection member 42 of the solar cell module 1, the intermediate sheet member 44 does not necessarily have to include the black layer 441. That is, for example, the intermediate sheet member 44 may have a multi-layer structure of a reflective layer 442 and a transparent resin layer 443. Even if the intermediate sheet member 44 does not have a black layer 441, the back surface protection member 42 includes a layer of the same color or similar color as the solar cell 10, so that they appear integrated, which makes it possible to improve the design.

(Embodiment 2)
FIG. 5 is a plan view showing a schematic configuration of a solar cell module 1 relating to embodiment 2 of the present invention, and FIG. 6 is a cross-sectional view showing an example of the internal structure of the solar cell module 1, including a laminated structure including an intermediate sheet member 44.

The solar cell module 1 according to this embodiment is characterized by the arrangement of the intermediate sheet member 44, but the other configurations are the same as those of the solar cell module 1 according to embodiment 1.

As shown in FIG. 6, an output section 50 that outputs the power generated in the solar cell 10 to the outside is provided on the back surface (lower side in the figure), which is the surface opposite the light receiving surface side of the back surface protection member 42. Although not shown in these figures, the solar cell module 1 has two extraction electrodes, a positive electrode side and a negative electrode side, and one end of each extraction electrode is electrically connected to the solar cell 10.

In the output section 50, the output lead section (output wiring) 51 of the extraction electrode penetrates the back surface protection member 42 and is led out to the outside of the solar cell module 1. The led out output lead section 51 is pulled into the terminal box 52 and electrically connected to an external output cable 53 via a connection terminal or the like. In a solar cell module 1 having such a structure, in order to take out the power generated in the solar cell 10 to the outside, an opening is provided in the back surface protection member 42 to lead out the output lead section 51, and wiring is performed to reach the terminal box 52. Therefore, in this wiring method, moisture such as water vapor is easily infiltrated from the output lead section 51 and the opening of the back surface protection member 42.

In contrast, in the solar cell module 1 according to this embodiment, the intermediate sheet member 44 is provided in at least an area including the light receiving surface side of the output section 50. The output section 50 is provided, for example, between the solar cell groups 20 in the solar cell module 1. In the embodiment shown in FIG. 5, since the terminal box of the output section 50 is provided approximately in the middle of the solar cell module 1 in the first direction D1, the intermediate sheet member 44 is arranged in a long strip shape in the second direction D2 so as to include the middle part.

As shown in FIG. 6, the solar cell module 1 has a layered structure in the vicinity of the output section 50, in which, from the light-receiving surface side, a translucent substrate 41, a sealing material 43a (43) on the light-receiving surface side, a plurality of solar cells 10, a sealing material 43b (43) in the middle, an intermediate sheet member 44, a sealing material 43c (43) on the back surface side, and a back surface protection member 42 are arranged in this order. The output section 50 is disposed on the back surface side of the back surface protection member 42 in this layered structure, and the intermediate sheet member 44 is layered between the sealing material 43b and the sealing material 43c on the inside of the output section 50.

As a result, in the output section 50, where there is concern about the infiltration of moisture such as water vapor, the intermediate sheet member 44 is laminated on the back side of the solar cell module 1 in addition to the back side protective member 42, so that such infiltration of moisture can be prevented. This makes it possible to prevent moisture from the back side from reaching the sealing material 43b, suppress the generation of free acid in the EVA, and maintain adhesion between the back electrode 102 of the solar cell 10 and the sealing material 43.

In this way, when the intermediate sheet member 44 is provided in an area including at least the light receiving surface side of the output section 50, the back surface protection member 42 can be made of a sheet-like material common to the intermediate sheet member 44 and can include a reflective layer 442. In this case, the light incident on the solar cell module 1 passes through the light-transmitting substrate 41 and the sealing material 43 to reach the solar cell 10, and some of the incident light reaches the intermediate sheet member 44 or the back surface protection member 42 on the back surface side of the solar cell 10. In these intermediate sheet members 44 and back surface protection member 42, most of the infrared rays contained in the incident light are reflected by the reflective layer 442, and the temperature rise of the solar cell module 1 due to infrared absorption can be suppressed.

When the solar cell module 1 is viewed from the light-receiving surface side, the solar cell 10 and the intermediate sheet member 44 on its back surface side are visible through the light-transmitting substrate 41 and the sealing material 43. In areas where the intermediate sheet member 44 is not present, the back surface protection member 42, which has a common configuration with the intermediate sheet member 44, is visible. These include a layer of the same color or a similar color as the solar cell 10, so that the solar cell 10 and the intermediate sheet member 44, and the solar cell 10 and the back surface protection member 42 all appear integrated, improving the design.

As described above, the solar cell module 1 according to the present invention can suppress the intrusion of moisture from the back side, and can have a laminated structure with higher moisture resistance. This can suppress the generation of free acid in the EVA constituting the sealing material 43, making it possible to obtain a solar cell module 1 with high long-term reliability. In addition, by stacking the intermediate sheet member 44 mainly on the light-receiving surface side of the output unit 50 in correspondence with the position where the output unit 50 is provided, it is possible to provide doubly moisture resistance with the back protection member 42 and the intermediate sheet member 44 and prevent the intrusion of moisture from the output unit 50. The intermediate sheet member 44 is not limited to being provided in an area including the light-receiving surface side of the output unit 50, but may be provided in a wider area between the solar cell 10 and the back protection member 42, or in the entire area.

In the above-mentioned first and second embodiments, a standard-sized cell (full cell) divided in half is used as the solar cell 10 provided in the solar cell module 1, but the present invention is not limited to this, and may be, for example, a cell divided into one-fourth, or a full cell. The solar cell 10 may be a single-sided light receiving type or a double-sided light receiving type. The number and type of the solar cell 10 are not particularly limited, and for example, solar cells 10 made of various semiconductor materials such as polycrystalline semiconductors and thin-film semiconductors can be used.

The above-disclosed embodiments are illustrative in all respects and are not intended to be a basis for a restrictive interpretation. Therefore, the technical scope of the present invention is not interpreted solely by the above-disclosed embodiments, but is defined based on the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included.

REFERENCE SIGNS LIST 1 Solar cell module 10 Solar cell 101 Front surface electrode 102 Rear surface electrode 103 Bus bar electrode 20 Solar cell group 21 Solar cell string 31 Wiring material 32 End wiring member (wiring member)
33 Intermediate wiring member (wiring member)
40 Panel 41 Light-transmitting substrate 42 Back surface protection member 43 Sealing material 44 Intermediate sheet member 441 Black layer 442 Reflective layer 50 Output section 51 Output lead section 52 Terminal box 53 External output cable

Claims (4)

A solar cell module including a plurality of solar cells electrically connected between a light-transmitting substrate and a rear surface protection member and sealed with a sealing material,
an intermediate sheet member having a moisture resistance greater than that of the sealing material is provided between the solar cell and the back surface protection member;
a laminated structure in which the light-transmitting substrate, the sealing material, the solar cell, the sealing material, the intermediate sheet member, the sealing material, and the back surface protection member are disposed in this order from the light-receiving surface side,
The intermediate sheet member is
The solar cell is provided in the entire area between the solar cell and the back surface protection member,
A reflective layer that reflects light in a wavelength range of 700 nm or more in the entire region is included,
A solar cell module comprising: a black layer on the light-receiving surface side of the reflective layer, the black layer being in contact with the sealing material . The solar cell module according to claim 1 ,
an output section that outputs power generated by the solar cell to the outside is provided on a back surface of the back surface protection member, the back surface being the surface opposite to the light receiving surface;
The solar cell module, characterized in that the output section is disposed on the back surface side of the back surface protection member in the laminated structure. The solar cell module according to claim 1 or 2 ,
The solar cell module according to claim 1, wherein the intermediate sheet member and the rear surface protection member are made of a common sheet-like member. The solar cell module according to any one of claims 1 to 3 ,
13. A solar cell module, comprising: a reflecting layer of the intermediate sheet member which is a resin sheet containing any one of PTFE, ETFE, and PET.

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