JP7660404B2 - Solar Cell Module - Google Patents

Description

The present invention relates to a solar cell module.

When arranging many solar cells vertically and horizontally to form a solar cell module with a large area, a configuration is adopted in which a number of solar cells, each of which is made up of a number of solar cells arranged in a row in a first direction and connected together, are arranged in a row in a second direction (see, for example, Patent Document 1).

International Publication No. WO2018/003563

Generally, solar cell modules are formed in a rectangular shape when viewed from above. For this reason, the multiple solar cell strings that form one solar cell module are all the same. However, when mounting solar cell modules on various objects such as automobiles, it is desirable to be able to freely design the planar shape of the solar cell module to match the shape of the usable parts of the object. It is possible to arrange solar cell strings only in the rectangular area at the center of the solar cell module, but this reduces the area in which the incident light can be used, resulting in a low photoelectric conversion efficiency per area when viewed as a whole module.

By arranging solar cell strings of different lengths, it is possible to increase the effective area and improve the photoelectric conversion efficiency even if the planar shape of the solar cell module is not rectangular. However, if the number of solar cells is varied to change the length of the solar cell string, a difference will arise in the number of solar cell cells connected in series with other solar cell strings, resulting in an imbalance in the output voltage of the solar cell string. In addition, when the length of the solar cell string is adjusted according to the number of solar cell cells, the length of one solar cell becomes the smallest unit, resulting in an area at the end of the solar cell module where solar cells cannot be placed.

In view of this situation, the present invention aims to provide a solar cell module with a high degree of freedom in planar shape.

A solar cell module according to one aspect of the present invention has a plurality of solar cell strings each having a plurality of solar cell cells connected in a row in a first direction with their ends overlapping each other, and arranged in a row in a second direction intersecting the first direction, and at least one of the solar cell strings has a different overlap length between the solar cell cells in the first direction from at least one other of the solar cell strings.

In one aspect of the solar cell module of the present invention, the number of solar cells in all of the solar cell strings may be equal.

In a solar cell module according to one aspect of the present invention, the overlap length between the solar cell cells of the solar cell string at the end in the second direction may be greater than the overlap length between the solar cell cells of the solar cell string at the center in the second direction.

In one aspect of the solar cell module of the present invention, the solar cell may have a rectangular planar shape.

In a solar cell module according to one aspect of the present invention, the solar cell may have an electrode only on the back surface.

In a solar cell module according to one aspect of the present invention, the solar cell of the solar cell string in which the overlap length is greater than the other solar cell strings may have a greater output current per unit area than the solar cell of the other solar cell strings.

The solar cell module of the present invention has a high degree of freedom in terms of planar shape.

1 is a schematic plan view of a solar cell module according to one embodiment of the present invention; 2 is a schematic cross-sectional view of the solar cell module of FIG. 1 taken along line AA. 2 is a schematic cross-sectional view of the solar cell module of FIG. 1 taken along line BB.

Embodiments of the present invention will be described below with reference to the drawings. For convenience, hatching and component symbols may be omitted. In such cases, other drawings should be referenced. Also, for convenience, the dimensions of various components in the drawings have been adjusted for ease of viewing.

Figures 1 to 3 show a solar cell module 1 according to a first embodiment of the present invention. Figure 1 is a schematic plan view of the solar cell module 1, Figure 2 is a schematic cross-sectional view of the solar cell module 1 taken along line A-A, and Figure 3 is a schematic cross-sectional view of the solar cell module 1 taken along line B-B.

The solar cell module 1 includes a plurality of solar cell strings (first solar cell strings 11 at both ends and a plurality of second solar cell strings 12 on the inside), a front protective member 20 arranged on the front (incident surface) side of the solar cell strings 11, 12, a back protective member 30 arranged on the back side of the solar cell strings 11, 12, and a sealing material 40 filled in the gap between the front protective member 20 and the back protective member 30. The solar cell module 1 further includes wiring material (not shown) that connects the plurality of solar cell strings 11, 12.

The solar cell module 1 can have a shape other than a square when viewed from above. Specifically, the solar cell module 1 of this embodiment has an octagonal shape with the corners of a square chamfered when viewed from above.

The solar cell strings 11 and 12 each have a number of solar cell cells 13 that are connected in a row in the first direction with their ends overlapping. Specifically, one end of each solar cell 13 in the first direction is overlapped on the back side of the other end of the adjacent solar cell 13 in the first direction. In other words, the solar cell strings 11 and 12 have a so-called shingling structure. The solar cell cells 13 in the solar cell strings 11 and 12 may all be the same.

The multiple solar cell strings 11, 12 are arranged side by side in a second direction intersecting the first direction. In the figure, the spacing between the solar cell strings 11, 12 and the margin around the periphery of the solar cell module 1 are shown large for ease of understanding, but in reality, it is preferable that the solar cell strings 11, 12 are arranged over substantially the entire surface of the solar cell module 1 with the spacing between them and the margin around the periphery kept to a minimum.

It is preferable that all solar cells 13 are electrically connected in series within each solar cell string 11, 12. This simplifies the configuration of the solar cell strings 11, 12.

It is preferable that the number of solar cells 13 in the solar cell strings 11 and 12 are all equal. As a result, when the solar cell strings 11 and 12 are made up of the same solar cell cells 13 connected in series, the output voltage of the solar cell strings 11 and 12 is constant. Therefore, when multiple solar cell strings 11 and 12 are electrically connected, the output of all the solar cell strings 11 and 12 can be extracted without waste.

The length in the first direction of the first solar cell string 11 at the end in the second direction is smaller than the length in the first direction of the second solar cell string 12 at the center in the second direction in order to match the octagonal planar shape of the solar cell module 1. For this reason, the overlap length in the first direction between the solar cell cells 13 of the first solar cell string 11 is larger than the overlap length in the first direction between the solar cell cells 13 of the second solar cell string 12.

In each solar cell string 11, 12, it is preferable that the overlap length in the first direction between two adjacent solar cells 13 is approximately constant. This makes the output of each solar cell 13 approximately equal, allowing the multiple solar cells 13 to be used evenly.

The lower limit of the ratio of the maximum value to the minimum value of the average overlap length between the solar cells 13 of the solar cell strings 11 and 12 (the average value of the overlap length in the first direction between two adjacent solar cells 13 in each solar cell string 11 and 12) is preferably 105%, and more preferably 110%. On the other hand, the upper limit of the ratio of the maximum value to the minimum value of the average overlap length between the solar cells 13 of the solar cell strings 11 and 12 is preferably 500%, and more preferably 300%. By setting the ratio of the maximum value to the minimum value of the average overlap length between the solar cells 3 of the solar cell strings 11 and 12 to the lower limit or more, a clear difference can be made between the length of the first solar cell string 11 and the length of the second solar cell string 12. In addition, by setting the ratio of the maximum value to the minimum value of the average overlap length between the solar cells 13 of the solar cell strings 11 and 12 to the upper limit or less, the ineffective area (area shaded by adjacent solar cell 13) of each solar cell 13 can be reduced, and the increase in the device cost per output can be suppressed.

The average overlap length between the solar cells 13 of the solar cell strings 11 and 12 depends on the size of the solar cell 13, but is preferably 1 mm or more and 30 mm or less, and more preferably 2 mm or more and 20 mm or less. This makes it easy to form the solar cell strings 11 and 12, and allows the photoelectric conversion capacity of each solar cell 13 to be effectively utilized.

Inside the solar cell strings 11 and 12, the solar cells 13 are connected by a conductive connecting member called an interconnector. The length of the interconnector may be adjusted to match the average overlap length of the solar cells 13, but if the difference in the average overlap length of the solar cells 13 between the solar cell strings 11 and 12 is small, the interconnector connecting the solar cells 13 may be common.

When forming the solar cell strings 11 and 12, the solar cell 13 may be positioned using a jig created to achieve the desired overlap length, or may be positioned using a device that can arbitrarily position the solar cell 13 using computer control.

The solar cell 13 is preferably, but not limited to, a back electrode type solar cell that has an electrode only on the back surface. By using a back electrode type solar cell that does not have an electrode on the incident surface side to block light as the solar cell 13, a relatively high photoelectric conversion efficiency can be achieved. In addition, by adopting a back electrode type solar cell, the color of the solar cell module 1 when viewed from the front surface side becomes black overall, improving the aesthetic appearance of the solar cell module 1.

The solar cell 13 has a connection electrode to which an interconnector is connected in order to electrically connect with an adjacent solar cell 13. This connection electrode is preferably disposed in an area on the back surface of the solar cell 13 that is slightly toward the center in the first direction relative to an area that may be disposed on the front side of the adjacent solar cell 13. This makes it possible to suppress a decrease in the connectivity of the interconnector due to an increase in the average overlap length between the solar cell 13.

The planar shape of the solar cell 13 is preferably rectangular. By making the solar cell 13 rectangular, the overlapping area of the solar cell 13 can be made into a small strip with a constant width in the first direction, so that the area ratio of the effective area of the solar cell 13 (the area where the surface is not covered by adjacent solar cell 13 and where light actually enters and contributes to photoelectric conversion) can be increased. This reduces the manufacturing cost per output of the solar cell strings 11, 12 and ultimately the solar cell module 1.

It is preferable that the solar cells of the solar cell string 11, which has a longer overlap length than the other solar cell strings 12, have a larger output current per unit area than the solar cell cells of the other solar cell strings. This makes it possible to reduce the difference in output between the first solar cell string 11 and the second solar cell string 12, so that the output of all the solar cell strings 11, 12 can be extracted without waste. For this reason, it is desirable to make the output of all the solar cell strings 11, 12 as equal as possible.

For this reason, it is preferable to measure the short-circuit current Isc of each solar cell 13 and to separate the solar cells 13 used in the first solar cell string 11 from the solar cells 13 used in the second solar cell string 12 so that the output difference between the solar cell strings 11 and 12 is small. Specifically, the solar cell cells 13 can be separated using, for example, an index such as a value obtained by dividing the short-circuit current Isc by the planned effective area in the solar cell strings 11 and 12 that generate the short-circuit current Isc, or a value obtained by multiplying the short-circuit current Isc by the planned effective area ratio.

The front protective member 20 protects the solar cell cells 13 by covering the surfaces of the solar cell strings 11, 12, i.e., the solar cell 13, via the sealing material 40. The front protective member 20 can be formed from a plate-shaped or sheet-shaped material, and preferably has excellent light transmissivity and weather resistance. Specifically, examples of the material for the front protective member 20 include transparent resins such as acrylic resin or polycarbonate resin, and glass. In addition, the surface of the front protective member 20 may be processed to have an uneven shape or coated with an anti-reflective coating layer to suppress light reflection.

The backside protective member 30 covers the backside of the solar cell strings 11, 12 via the sealing material 40 to protect the solar cell cells 13. The backside protective member 30 can be formed from a plate-like or sheet-like material, like the frontside protective member 20, and preferably has excellent water-proofing properties. Specifically, examples of the backside protective member 30 include resin films such as polyethylene terephthalate (PET), polyethylene (PE), olefin-based resins, fluorine-containing resins, and silicone resins, laminates of the resin films and metal foils such as aluminum foils, transparent resins such as acrylic resins or polycarbonate resins, and glass.

The sealing material 40 seals and protects the solar cell strings 11 and 12, i.e., the solar cells 13, and in particular prevents moisture from coming into contact with the solar cells 13. For this reason, the sealing material 40 is interposed between the light-receiving surface of the solar cell 13 and the front protective member 20, and between the back surface of the solar cell 13 and the back protective member 30.

The sealing material 40 bonds the solar cell strings 11, 12 to the front protective member 20 and the back protective member 30, and also protects the solar cell 13 by eliminating gaps around the solar cell strings 11, 12. For this reason, the sealing material 40 is preferably a thermoplastic resin having translucency, such as ethylene/vinyl acetate copolymer (EVA), ethylene/α-olefin copolymer, ethylene/vinyl acetate/triallyl isocyanurate (EVAT), polyvinyl butyrate (PVB), acrylic resin, urethane resin, or silicone resin.

As described above, the solar cell module 1 includes a first solar cell string 11 and a second solar cell string 12 in which the overlap lengths of the solar cells 13 in the first direction are different, and thus has a planar shape with rounded corners when viewed from above, while the ineffective area where the solar cells 13 are not arranged is small, resulting in excellent photoelectric conversion efficiency per area.

The solar cell module 1 can be easily redesigned by changing the overlap length in the first direction of the multiple solar cells 13 of the solar cell strings 11 and 12 to match its planar shape. In other words, the solar cell module 1 has a high degree of freedom in its design with respect to its planar shape.

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.

The solar cell module according to the present invention may have any planar shape. Therefore, in the solar cell module according to the present invention, the number of solar cell strings in which the overlap length of the solar cell differs from other solar cell strings is not limited, and there may be three or more types of solar cell strings in which the overlap length of the solar cell differs. Furthermore, in order to form a solar cell module having a planar shape in which the central portion in the first direction is narrowed, a solar cell string in which the overlap length of the solar cell is large may be arranged in the central portion in the second direction.

Reference Signs List 1 Solar cell module 11, 12 Solar cell string 13 Solar cell 20 Front protective member 30 Back protective member 40 Sealing material

Claims (5)

a plurality of solar cell strings each including a plurality of solar cell cells connected in a row in a first direction so that their ends overlap each other, and arranged side by side in a second direction intersecting the first direction;
At least one of the solar cell strings has a different overlap length between the solar cells in the first direction from at least one other of the solar cell strings;
A solar cell module, wherein the solar cell of the solar cell string having the overlap length greater than those of the other solar cell strings has a larger output current per unit area than the solar cell of the other solar cell strings. The solar cell module according to claim 1, wherein the number of solar cells in all of the solar cell strings is equal. The solar cell module according to claim 1 or 2, wherein the overlap length between the solar cell cells of the solar cell string at the end in the second direction is greater than the overlap length between the solar cell cells of the solar cell string at the center in the second direction. The solar cell module according to any one of claims 1 to 3, wherein the planar shape of the solar cell is rectangular. The solar cell module according to any one of claims 1 to 4, wherein the solar cell has an electrode only on the back surface.

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