solar cell module

Abstract

Provided is a high-output and highly reliable solar cell module. A solar cell module 1 according to an embodiment of the present invention comprises a plurality of solar cells 11 disposed side by side in a first direction, and connecting members 12 connecting the plurality of solar cells. The solar cell module 1 further comprises a plurality of solar cell strings 10 disposed side by side in a second direction intersecting the first direction, and a wiring member 20 disposed to extend in the second direction and connecting the connecting members. The solar cells each has a plurality of connecting electrodes 116, 117 on a back surface thereof. The connecting members include a holding film 121 stacked continuously on the back surface side of the plurality of solar cells, and a plurality of connecting wires 122 which are held on a front surface side of the holding film, extend in parallel to each other in the first direction, are connected to the connecting electrodes, and have ends extending out of the holding film. The ends of the plurality of connecting wires extending out of the holding film are folded onto a back surface side of the holding film while being displaced toward one side in the second direction.

Description

[Technical Field]

[0001] The present invention relates to a solar cell module. [Background technology]

[0002] Generally, a solar cell module comprising a large number of solar cells is formed by using a plurality of solar cell strings, each formed by connecting a plurality of solar cells arranged in a row, and connecting the plurality of solar cell strings arranged in parallel with connecting members. Usually, an interconnector for connecting each solar cell to an adjacent solar cell is attached to each solar cell, and the connecting member for connecting the solar cell strings is connected to the interconnector attached to the solar cell at the end of the solar cell string.

[0003] To improve the area efficiency of the solar cell module, the connection member may be disposed on the back side of the solar cell string. In this case, folding back the interconnector may cause the interconnector to break or the body of the solar cell to be damaged by being pressed by the interconnector. In response to this, Patent Document 1 proposes a configuration in which bending stress is prevented by connecting a separate conductive wiring member to the interconnector, and excessive bending is prevented by attaching a protective member made of solder or the like to the bending portion of the interconnector. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-34149 Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration of Patent Document 1, wiring members are connected and protective members are attached outside the solar cell string in a plan view, so there is room for further improvement in the area efficiency of the solar cell module. Furthermore, particularly in back electrode solar cells, a configuration is known in which each solar cell is provided with a large number of electrodes arranged in a matrix, and a large number of wires are used to collect current from the multiple electrodes within the solar cell and connect adjacent solar cells to each other. In such a configuration, a large number of wires are used as interconnectors, so adopting the configuration of Patent Document 1 could complicate the manufacturing process, potentially increasing manufacturing costs and increasing the risk of poor connection.

[0006] An object of the present invention is to provide a solar cell module that has high output and high reliability. [Means for solving the problem]

[0007] A solar cell module according to one embodiment of the present invention comprises a plurality of solar cell strings each arranged in a first direction and a connection member connecting the plurality of solar cell cells, the solar cell strings each arranged in a second direction intersecting the first direction, and a wiring member arranged to extend in the second direction and connecting the connection members, the solar cell having a plurality of connection electrodes on its back surface, the connection member comprising: a support film continuously laminated on the back surface side of the plurality of solar cell cells; and a plurality of connection wires held on the front surface side of the support film, extending parallel to each other and in the first direction, connected to the connection electrodes, and having ends extending from the support film, the ends of the plurality of connection wires extending from the support film being shifted to one side of the second direction and folded back onto the back surface side of the support film.

[0008] In the solar cell module according to one aspect of the present invention, the minimum radius of curvature of the folded portion of the cross-sectional center line of the connecting wire may be three times or more the equivalent circle diameter of the connecting wire.

[0009] In a solar cell module according to one embodiment of the present invention, the tip of the connecting wire arranged on the back side of the retaining film may be arranged offset in the second direction by 3 mm to 20 mm from the portion arranged on the front side of the retaining film.

[0010] In the solar cell module according to one aspect of the present invention, the connecting wire may be folded back inside the solar cell in a plan view.

[0011] In the solar cell module according to one aspect of the present invention, the connecting wire may have a flat cross section and be coated with solder. [Effects of the Invention]

[0012] The solar cell module according to the present invention has high output and high reliability. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a schematic rear view of the solar cell module of the present invention. [Figure 2] 2 is a cross-sectional view of the end portion of the solar cell module of FIG. 1 taken along line AA. [Figure 3] FIG. 2 is an enlarged rear view of an end portion of the solar cell of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, hatching and component reference numerals may be omitted. In such cases, other drawings should be referenced. Furthermore, the dimensions of various components in the drawings have been adjusted for clarity.

[0015] First Embodiment Fig. 1 is a schematic back view of a solar cell module 1 according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view of an end portion of a solar cell string 10 taken along line AA. Fig. 3 is an enlarged back view of the end portion of the solar cell string 10.

[0016] The solar cell module 1 comprises a plurality of solar cell strings 10, a wiring member 20 that electrically connects the plurality of solar cell strings 10, a surface protection member 30 that is arranged on the front (incident surface) side of the solar cell strings 10, a back protection member 40 that is arranged on the back side of the solar cell strings 10, and a sealing material 50 that is filled in the gap between the surface protection member 30 and the back protection member 40 (around the solar cell strings 10).

[0017] The solar cell string 10 includes a plurality of solar cells 11 arranged side by side in a first direction, and a connection member 12 that connects the plurality of solar cells 11 together.

[0018] As shown in Figure 2 or Figure 3, the solar cell 11 has a semiconductor substrate 111, a plurality of first semiconductor layers 112 and a plurality of second semiconductor layers 113 of a different conductivity type from the first semiconductor layers 112, which extend in a second direction intersecting the first direction and are formed alternately in the first direction on the back surface of the semiconductor substrate 111 (the main surface opposite to the main surface into which light is incident), a first collecting electrode 114 and a second collecting electrode 115 arranged on the back surfaces of the first semiconductor layer 112 and the second semiconductor layer 113 so as to extend in the second direction, and a first connecting electrode 116 and a second connecting electrode 117 partially stacked on the first collecting electrode 114 and the second collecting electrode 115, respectively.

[0019] The semiconductor substrate 111 is formed of a crystalline silicon material such as single crystal silicon or polycrystalline silicon. The semiconductor substrate 111 is, for example, an n-type semiconductor substrate obtained by doping a crystalline silicon material with an n-type dopant. An example of the n-type dopant is phosphorus (P). The semiconductor substrate 111 functions as a photoelectric conversion substrate that absorbs incident light from the light-receiving surface side and generates photocarriers (electrons and holes). By using crystalline silicon as the material for the semiconductor substrate 111, dark current is relatively small, and a relatively high output (stable output regardless of illuminance) can be obtained even when the intensity of incident light is low.

[0020] The first semiconductor layer 112 and the second semiconductor layer 113 have different conductivity types. For example, the first semiconductor layer 112 is formed from a p-type semiconductor, and the second semiconductor layer 113 is formed from an n-type semiconductor. The first semiconductor layer 112 and the second semiconductor layer 113 can be formed, for example, from an amorphous silicon material containing a dopant that imparts the desired conductivity type. An example of a p-type dopant is boron (B), and an example of an n-type dopant is phosphorus (P), as described above.

[0021] The first semiconductor layer 112 and the second semiconductor layer 113 each extend over the entire length of the semiconductor substrate 111 in the second direction and are formed in a strip shape having a constant width in the first direction. In the solar cell 11, the first semiconductor layer 112 and the second semiconductor layer 113 are preferably disposed in close contact with each other so as to cover substantially the entire surface of the semiconductor substrate 111. The first semiconductor layer 112 and the second semiconductor layer 113 attract carriers generated in the semiconductor substrate 111.

[0022] The first semiconductor layer 112 and the second semiconductor layer 113 can be formed in order by forming a mask on the rear surface of the semiconductor substrate 111 and stacking semiconductor materials using a film formation technique such as CVD or PVD.

[0023] First collecting electrode 114 and second collecting electrode 115 are stacked on the back surface sides of the central portions in the first direction of first semiconductor layer 112 and second semiconductor layer 113, respectively. First collecting electrode 114 and second collecting electrode 115 are preferably disposed over the entire lengths of first semiconductor layer 112 and second semiconductor layer 113. First collecting electrode 114 and second collecting electrode 115 extract charges from first semiconductor layer 112 and second semiconductor layer 113.

[0024] The first collecting electrode 114 and the second collecting electrode 115 are made of a conductive material. For example, the first collecting electrode 114 and the second collecting electrode 115 can be formed by printing (e.g., screen printing) and baking a conductive paste containing conductive particles and a resin binder. The first collecting electrode 114 and the second collecting electrode 115 can also be formed by patterning by etching a metal layer deposited by sputtering, plating, or the like.

[0025] The first connection electrodes 116 are stacked on the back surfaces of the respective first collecting electrodes 114 at intervals so as to be arranged in a matrix in the first and second directions across the entire solar cell 11. The second connection electrodes 117 are stacked on the back surfaces of the respective second collecting electrodes 115 at intervals so as to be arranged in a matrix in an alternating manner with the first connection electrodes 116 in the first and second directions across the entire solar cell 11. The first connection electrodes 116 and the second connection electrodes 117 are electrodes for connecting the first collecting electrodes 114 and the second collecting electrodes 115 to the wiring member 20, which will be described later. The first connection electrodes 116 and the second connection electrodes 117 partially raise the height of the first collecting electrodes 114 and the second collecting electrodes 115, thereby preventing a short circuit caused by the wiring member 20 coming into contact with unintended portions of the first collecting electrodes 114 and the second collecting electrodes 115.

[0026] In each solar cell string 10, the multiple solar cells 11 can be arranged with their orientation directions changed to facilitate electrical connection by the connection members 12. For example, when all the solar cells 11 in the solar cell string 10 are electrically connected in series, it is preferable that the orientations of the solar cells 11 are alternately changed by 180° so that the first connection electrodes 116 of the solar cells 11 are aligned with the second connection electrodes 117 of the adjacent solar cell 11 in the first direction.

[0027] The connection member 12 has a support film 121 that is continuously laminated on the back side of the multiple solar cell 11, and multiple connection wires 122 that are held on the front side of the support film 121, extend parallel to each other and in a first direction, are connected to the first connection electrode 116 and the second connection electrode 117, respectively, and have at least some ends extending from the support film 121.

[0028] The retaining film 121 holds the connection wires 122 at equal intervals in the second direction. The retaining film 121 is laminated on the back side of the plurality of solar cell 11 arranged side by side in the first direction while holding the connection wires 122, thereby positioning the connection wires 122 with respect to the first connection electrodes 116 and the second connection electrodes 117. The retaining film 121 can also function as a layer that is adhered to the solar cell 11 and protects the back side of the solar cell 11.

[0029] The holding film 121 has adhesiveness at least on the surface that holds the connection wire 122. The holding film 121 may be a laminate having a base film and an adhesive layer, or may be a single-layer film formed from a thermoplastic resin that can be thermocompressed. Examples of thermoplastic resins that can be thermocompressed include ethylene / vinyl acetate copolymer (EVA), ethylene / α-olefin copolymer, ethylene / vinyl acetate / triallyl isocyanurate (EVAT), polyvinyl butyrate (PVB), acrylic resin, urethane resin, and silicone resin.

[0030] The holding film 121 may have openings 123 for regularly cutting the connecting wires 122, as will be described later. That is, the openings 123 are formed by partially punching out the holding film 121 and the connecting wires 122 while the holding film 121 holds the connecting wires 122. The openings 123 allow the sealing material 50 to flow into the gaps between the solar cell 11 and the holding film 121, thereby ensuring protection of the solar cell 11, and thereby contributing to improving the reliability of the solar cell module 1.

[0031] In order to enable the connecting wires 122 to be folded back on the back surfaces of the solar cells 11 at both ends in the first direction, it is preferable that the holding film 121 exposes the outer ends in the first direction of the solar cells 11 at both ends in the first direction. This increases the ratio of the area occupied by the solar cells 11 to the entire area of ​​the solar cell module 1, which contributes to improving the output of the solar cell module 1.

[0032] The connecting wire 122 connects the first connecting electrode 116 and the second connecting electrode 117 of the solar cell 11, thereby electrically connecting the solar cell 11 and enabling the solar cell string 10 to be treated as a single element.

[0033] As described above, the connecting wire 122 may be regularly divided depending on the manner of electrical connection of the solar cell 11. By orienting the solar cell 11 alternately in directions that differ by 180° and partially cutting the connecting wire 122 alternately in the second direction at intervals of twice the pitch of the solar cell 11, all of the solar cell 11 can be electrically connected in series. Alternatively, by orienting the solar cell 11 in the same direction and leaving the connecting wire 122 uncut so that it extends over the entire length of the solar cell string 10, all of the solar cell 11 can be electrically connected in parallel. By selecting the orientation of the solar cell 11 and the cutting pattern of the connecting wire 122, multiple solar cell 11 may be connected in a circuit configuration having parallel and series connections.

[0034] An end of the connection wire 122 at one end in the first direction, which is connected to the first connection electrode 116 of the solar cell 11 at one end in the first direction, and an end of the connection wire 122 at the other end in the first direction, which is connected to the second connection electrode 117 of the solar cell 11 at the other end in the first direction, each extend from the holding film 121. More specifically, at one end in the first direction, as shown in Fig. 2, the connection wire 122 connected to the first connection electrode 116 of the solar cell 11 extends from the holding film 121. At the other end in the first direction, as shown in Fig. 3, the connection wire 122 connected to the second connection electrode 117 of the solar cell 11 extends from the holding film 121.

[0035] The end of the connecting wire 122 extending from the holding film 121 is folded back onto the back surface of the holding film 121, shifted to one side in the second direction. That is, the folded back portion of the connecting wire 122 is positioned away from the portion held by the holding film 121 in a plan view. This prevents the folded back portion of the connecting wire 122 from breaking or the solar cell 11 to which the folded back portion of the connecting wire 122 is pressed against the solar cell 11 from being damaged when a force acts on the solar cell module 1 in the thickness direction due to a heat press or the like during manufacturing. The shifted direction of the folded back portion of the connecting wire 122 may be on the same side as the second direction in absolute coordinates, or may be on the same side as the second direction based on the extending direction of the connecting wire 122. As described above, the connecting wire 122 is preferably folded back inside the solar cell 11 in a plan view in order to increase the output per area of ​​the solar cell module 1.

[0036] A metal wire such as copper or aluminum can be used as the connecting wire 122. The connecting wire 122 is preferably coated in advance with solder for connecting to the first connecting electrode 116 and the second connecting electrode 117. This allows the connecting wire 122 to be connected to the first connecting electrode 116 and the second connecting electrode 117 by stacking the connecting member 12 on the solar cell 11 and hot pressing it, thereby reducing the manufacturing cost of the solar cell module 1.

[0037] The connecting wire 122 may have a flat cross section in which the thickness is smaller than the width. This allows the contact area with the holding film 121 to be increased while ensuring sufficient flexibility of the connecting wire 122, facilitating the formation of the connecting member 12 and allowing the connecting wire 122 to be accurately positioned relative to the first connecting electrode 116 and the second connecting electrode 117. If the aspect ratio (thickness / width) of the cross section is too large, the connecting wire 122 may lack flexibility in the width direction. A specific aspect ratio of the cross section of the connecting wire 122 may be, for example, 0.7 or more and 0.9 or less.

[0038] The lower limit of the minimum radius of curvature at the folded portion of the cross-sectional center line of the connecting wire 122 is preferably three times, and more preferably five times, the equivalent circle diameter of the connecting wire 122. On the other hand, the lower limit of the minimum radius of curvature of the connecting wire 122 is preferably two times, and more preferably one time, the arrangement pitch of the connecting wire 122. By setting the minimum radius of curvature of the connecting wire 122 to be equal to or greater than the lower limit, damage to the connecting wire 122 and the solar cell can be more reliably prevented. Furthermore, by setting the minimum radius of curvature of the connecting wire 122 to be equal to or less than the upper limit, the folded connecting wire 122 does not protrude in the second direction from the solar cell 11, preventing a deterioration in the aesthetic appearance of the solar cell module 1.

[0039] Specifically, the lower limit of the amount of displacement in the second direction of the tip (the folded tip) of the connecting wire 122 arranged on the back surface of the holding film 121 from the part arranged on the front surface of the holding film 121 is preferably 3 mm, and more preferably 5 mm. On the other hand, the upper limit of the amount of displacement of the folded tip of the connecting wire 122 is preferably 20 mm, and more preferably 15 mm. By setting the amount of displacement of the folded tip of the connecting wire 122 to be equal to or greater than the lower limit, damage to the connecting wire 122 and the solar cell 11 can be reliably prevented. Furthermore, by setting the amount of displacement of the folded tip of the connecting wire 122 to be equal to or less than the upper limit, it is possible to prevent the folded connecting wire 122 from protruding from the solar cell 11.

[0040] The wiring members 20 are arranged to extend in the second direction on the back side of the connecting members 12, and connect between the connecting members 12. More specifically, the wiring members 20 are arranged at both ends in the first direction of the multiple solar cell strings 10, and are connected to the portions of the connecting wires 122 that are folded back to the back side of the holding film 121. The wiring members 20 may be connected after each connecting wire 122 is folded back to the back side of the holding film 121, but by connecting each connecting wire 122 before bending it, the connecting wires 122 can be folded back easily and accurately.

[0041] The wiring member 20 may be any conductive material, typically a strip-shaped metal foil or metal plate.

[0042] The surface protection member 30 is a layer that protects the surface side of the solar cell string 10. The surface protection member 30 is made of a transparent, scratch-resistant material such as glass, polycarbonate, or acrylic resin. The surface protection member 30 preferably has a sufficient thickness to provide the strength to maintain the shape of the solar cell module 1. Furthermore, by using a surface protection member 30 that has been molded into a desired shape in advance, a solar cell module 1 with the desired shape can be obtained.

[0043] The surface of the surface protection member 30 may be textured or may be coated with an anti-reflection coating layer. By using such a surface protection member 30, the surface protection member 30 is less likely to reflect incident light, allowing more light to be guided to the solar cells 11 and improving the photoelectric conversion efficiency of the solar cell module 1.

[0044] The back surface protection member 40 is a layer that protects the back surface side of the solar cell string 10. The material of the back surface protection member 40 is not particularly limited, but a material that prevents the intrusion of water and the like (highly water-resistant) is preferable. Specifically, the back surface protection member 40 can be formed from resins such as polyethylene terephthalate (PET), acrylic resin, polyethylene (PE), olefin-based resin, fluorine-containing resin, and silicone-containing resin. The back surface protection member 40 may also be a laminate of a resin layer and a metal layer such as aluminum foil. This configuration can improve the barrier properties of the back surface protection member 40.

[0045] The sealing material 50 seals the space around the solar cells 11 between the front surface protection member 30 and the back surface protection member 40. The sealing material 50 particularly prevents moisture and the like from penetrating and coming into contact with the solar cell string 10. This prevents deterioration of the solar cell string 10, and in particular the solar cells 11.

[0046] The encapsulant 50 is formed from a transparent material that has adhesion to the solar cell string 10 and the surface protection member 30. The encapsulant 50 is preferably formed from a thermoplastic material so that the gap between the solar cell string 10 and the surface protection member 30 can be sealed by sandwiching a sheet-like material between the solar cell string 10 and the surface protection member 30 and between the solar cell string 10 and the back surface protection member 40 and then hot pressing the sheet-like material. Specifically, the encapsulant 50 can be formed from, for example, ethylene / vinyl acetate copolymer (EVA), ethylene / α-olefin copolymer, ethylene / vinyl acetate / triallyl isocyanurate (EVAT), polyvinyl butyrate (PVB), acrylic resin, urethane resin, silicone resin, or the like.

[0047] As described above, the solar cell module 1 connects the wiring members to the connection wires 122 inside the solar cell string 10, thereby increasing the output power by increasing the area ratio of the solar cell 11. Furthermore, the solar cell module 1 has the connection wires 122 folded back while shifted in the second direction, so that even if a force acts in the thickness direction of the solar cell module 1, the connection wires 122 and the solar cell 11 are unlikely to be damaged, resulting in excellent reliability.

[0048] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and various modifications and variations are possible. For example, in the solar cell module according to the present invention, the configuration of the solar cell is not limited to the configuration described above and may be, for example, a double-sided electrode solar cell. Furthermore, the solar cell of the solar cell module according to the present invention may have components other than those described above, such as an insulating layer, an intrinsic semiconductor layer, an anti-reflection layer, etc.

[0049] In the solar cell module according to the present invention, the solar cell string may have a so-called shingling structure, in which an end portion of one solar cell in the first direction is arranged overlapping the back surface of an end portion of the other solar cell in the first direction of an adjacent solar cell. Furthermore, in the solar cell module according to the present invention, the number of solar cell strings and the number of solar cells included in the solar cell string are not particularly limited. [Explanation of symbols]

[0050] 1. Solar cell module 10 solar cell strings 11 Solar cell 12 Connecting member 20 Wiring materials 30 Surface protection material 40 Back surface protection material 50 Encapsulating material 111 Semiconductor substrate 112 First semiconductor layer 113 Second semiconductor layer 114 First collecting electrode 115 Second collecting electrode 116 First connection electrode 117 Second connection electrode 121 Holding Film 122 connecting wires 123 Aperture

Claims

1. a plurality of solar cell strings each including a plurality of solar cell strings arranged in a first direction and connection members connecting the plurality of solar cell strings, the solar cell strings being arranged in a second direction intersecting the first direction; a wiring member arranged to extend in the second direction and connecting the connection members; Equipped with the solar cell has a plurality of connection electrodes on a rear surface; The connecting member is a support film laminated continuously on the rear surface side of the plurality of solar cells; and a plurality of connection wires held on the front surface side of the support film, extending parallel to each other and in the first direction, connected to the connection electrodes, and having ends extending from the support film, A solar cell module in which the ends of the multiple connection wires extending from the retaining film are folded back onto the back side of the retaining film, shifted to one side of the second direction so as not to overlap with the portions of the multiple connection wires held by the retaining film.

2. 2. The solar cell module according to claim 1, wherein the minimum radius of curvature at the folded-back portion of the cross-sectional center line of the connecting wire is at least three times the equivalent circle diameter of the connecting wire.

3. The solar cell module according to claim 1 , wherein the connecting wire is folded back inside the solar cell in a plan view.

4. The solar cell module according to claim 1 , wherein the connecting wire has a flat cross section and is coated with solder.

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