JP7731767B2 - solar cell module - Google Patents

Description

The present invention relates to a solar cell module.

Conventionally, solar cell modules have been proposed in which the periphery of the power-generating cells is painted for aesthetic purposes (Patent Document 1). This solar cell module includes a back sheet, an adhesive layer formed on the back sheet, and a wiring sheet (conductive sheet member) provided on the back sheet with the adhesive layer formed thereon. The solar cell module also includes multiple solar cells (power-generating cells) provided on the wiring sheet, a light-receiving surface-side sealing material provided in order on the solar cells, and a cover glass.

This solar cell module has multiple cell groups, each consisting of a row of solar cells. Furthermore, the solar cell module has all areas other than the multiple cell groups painted black, improving its appearance and design (paragraph 0090).

Japanese Patent Application Laid-Open No. 2020-170815

However, when black-painted areas are provided on the light-receiving side of such solar cell modules in order to conceal wiring materials and achieve a high level of design, direct sunlight may enter the solar cell module at an angle relative to the normal direction, depending on the installation angle, orientation, and time of day. In such cases, the black-painted areas (paint) may block sunlight from reaching some solar cells (power-generating cells). If the amount of light received by a solar cell whose sunlight is blocked by the paint film decreases, that cell may become a resistor within the module, reducing the power generation of cells other than that cell, potentially making it impossible to achieve the desired output. As such, there is a risk of a decrease in the power generation efficiency of the entire solar cell module, including solar cells whose sunlight is not blocked.

The present invention aims to provide a solar cell module that can suppress output reduction even when a decorative layer such as a coating film is formed on the surface of the protective plate (glass).

The solar cell module of the present invention comprises a solar cell string, a translucent protective plate overlaid on the light incident side of the solar cell string, and a decorative layer formed on the light incident side surface of the protective plate that attenuates or blocks light in the thickness direction. The solar cell string has power generating cells that generate electricity by receiving light and dummy cells that are not electrically connected to the power generating cells and do not contribute to the power generation of the solar cell string, and the dummy cells are positioned closer to the decorative layer than the power generating cells in a planar view.

With this configuration, dummy cells that do not contribute to power generation are placed in the solar cell string in areas where sunlight is blocked or reduced by the decorative layer. This prevents the power generating cells from being affected by the blocking or reduction of sunlight by the decorative layer, preventing a decrease in the power generating efficiency of the solar cell string. In this way, the dummy cells can prevent a decrease in the power generating efficiency of the solar cell string, thereby preventing a decrease in the output of the solar cell module.

Furthermore, in the solar cell module, the power generating cells and the dummy cells may have the same shape in plan view.

This configuration allows the power generating cells and dummy cells to have the same appearance when viewed from above, so the appearance of the solar cell module is not marred even when dummy cells are placed.

Furthermore, in the solar cell module, the power generating cells may be elongated, and in the solar cell string, multiple power generating cells may be connected in a single ring configuration.

With this configuration, in a solar cell string in which multiple power generating cells are connected in a single pattern, the individual power generating cells are small, and output is likely to decrease due to the effects of sunlight being blocked or dimmed by the decorative layer. Therefore, this configuration can effectively prevent output reduction due to the decorative layer in a solar cell module equipped with such a solar cell string.

Furthermore, in the solar cell module, the dummy cells may be arranged at both ends of the solar cell string related to the single connection in the connection direction.

With this configuration, even if the decorative layer blocks or reduces sunlight on either side of the shingled connection, it is possible to address the reduction in output caused by the decorative layer blocking or reducing sunlight.

Furthermore, in the solar cell module, the decorative layer may be a coating film formed on the surface of the protective plate.

This configuration effectively prevents output reduction caused by decorative layers in solar cell modules that use common aesthetic techniques (painting).

Furthermore, in the solar cell module, the coating film may be formed by forming a plurality of light-shielding regions and a plurality of light-transmitting regions adjacent to each other on the surface of the protective plate, so that the combination of the light-shielding regions and the light-transmitting regions reduces light in the thickness direction.

With this configuration, the solar cell module's coating, which combines light-shielding and light-transmitting areas, ensures a sense of unity when viewed from the outside, while allowing sunlight to partially enter through the coating, mitigating the effects of sunlight blocking or dimming caused by the decorative layer, thereby effectively preventing output reduction caused by the decorative layer.

As described above, the present invention provides a solar cell module that can suppress output reduction even when a decorative layer such as a coating film is formed on the surface of the protective plate (glass).

FIG. 1 is a schematic plan view of a solar cell module according to this embodiment. FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. FIG. 3 is a schematic plan view of a solar cell module according to a comparative example. FIG. 4 is a schematic cross-sectional view taken along the line IV-IV in FIG.

Embodiments of the present invention will be described below with reference to Figures 1 to 4.

As shown in Figure 2, the solar cell module 1 comprises a solar cell string 2, a translucent protective plate 3 overlaid on the light incident side of the solar cell string 2, and a decorative layer 4 formed on the light incident surface of the protective plate 3, which provides light reduction or blocking in the thickness direction. The solar cell module 1 also comprises a sealing material 5 provided between the solar cell string 2 and the protective plate 3. The solar cell module 1 further comprises a frame 6 arranged on the outer edge of the protective plate 3. This solar cell module 1 is plate-shaped and is installed, for example, on the roof of a building such as a private home, with its main surface (light-receiving surface) facing upward (towards the sun).

The solar cell string 2 has power generating cells 20 that generate electricity by receiving light, and dummy cells 21 that are not electrically connected to the power generating cells 20 and do not contribute to the power generation of the solar cell string 2. Furthermore, in the solar cell string 2, as shown in Figure 1, the dummy cells 21 are positioned closer to the decorative layer 4 than the power generating cells 20 in a plan view.

On the other hand, in the solar cell module 11 according to the comparative example, as shown in Figures 3 and 4, the solar cell string 12 does not include dummy cells and is composed only of power-generating cells 120. Therefore, sunlight is blocked by the decorative layer 4 from reaching some of the power-generating cells 120. Specifically, in this solar cell module 11, the decorative layer 4 blocks sunlight from reaching all or part of the power-generating cells 120a, 120b that are close to the decorative layer 4 in a planar view (see Figure 4). When the amount of light received by the power-generating cells 120a, 120b that are blocked by the decorative layer 4 decreases, the power-generating cells 120a, 120b act as resistance within the solar cell module 11, and the power generation of the power-generating cells 120c, 120d, and 120e other than the power-generating cells 120a, 120b in this solar cell module 11 also decreases, resulting in a phenomenon in which the desired output cannot be secured. As a result, there was a risk that the power generation efficiency of the entire solar cell module 11 would decrease, including the power generation cells 120c, 120d, and 120e, which were not blocked by the influence of the decorative layer 4.

In contrast, according to the solar cell module 1 of this embodiment, dummy cells 21 that do not contribute to power generation are arranged in the solar cell string 2 in the portion where sunlight is blocked or dimmed by the decorative layer 4 (see Figure 2). This prevents the power generating cells 20 from being affected by the blocking or dimming of sunlight by the decorative layer 4, thereby preventing a decrease in the power generation efficiency of the solar cell string 2. In this way, the dummy cells 21 can prevent a decrease in the power generation efficiency of the solar cell string 2, thereby preventing a decrease in the output of the solar cell module 1.

In addition, in this solar cell string 2, the power generating cells 20 and the dummy cells 21 have the same shape at least in a plan view (see Figure 1). In this embodiment, the power generating cells 20 and the dummy cells 21 have approximately the same thickness, and the color of the dummy cells 21 is also close to the color of the power generating cells 20. This allows the power generating cells 20 and the dummy cells 21 to have the same appearance when viewed through the protective plate 3 in a plan view, so the appearance of the solar cell module 1 is not marred even when the dummy cells 21 are placed.

Furthermore, in the solar cell string 2, each power generating cell 20 has an elongated shape, and multiple power generating cells 20 are connected in a shingle pattern. A shingle pattern is a connection in which the elongated power generating cells 20 are sequentially arranged so that the long sides of each power generating cell 20 overlap, like roofing shingles. In a solar cell string 2 in which multiple power generating cells 20 are connected in a shingle pattern like this, each power generating cell 20 is smaller than other connection methods, and output reduction due to sunlight shading or dimming caused by the decorative layer 4 is more likely to occur. Therefore, in a solar cell module 1 equipped with such a solar cell string 2, countermeasures against output reduction caused by the decorative layer 4 can be effectively implemented.

The solar cell string 2 has at least one power generating cell 20, and specifically, has multiple power generating cells 20. Each power generating cell 20 has the same size (in a single-connected solar cell string 2, the width dimension of each power generating cell 20). Each power generating cell 20 is, for example, rectangular plate-shaped.

The solar cell string 2 also has at least one dummy cell 21, and more specifically, a plurality of dummy cells 21. Each dummy cell 21 has the same size (in a solar cell string 2 connected in a single ring, the width of each dummy cell 21).

The dummy cells 21 may be, for example, resin plates or metal plates. Furthermore, the dummy cells 21 may have the same configuration as the power generation cells 20 and not be electrically connected to other power generation cells 20. Furthermore, the dummy cells 21 are positioned so as not to overlap the decorative layer 4 in a plan view.

In this solar cell string 2, the shapes of the power generating cells 20 and the dummy cells 21 are also the same in cross section (see Figure 2). The shapes of the power generating cells 20 and the dummy cells 21 can be different to the extent that the appearance of the solar cell module 1 is not impaired. For example, if the power generating cells 20 and the dummy cells 21 have the same shape in plan view, the shape and size of the power generating cells 20 may be different from the shape and size of the dummy cells 21.

In addition, in this solar cell string 2, dummy cells 21 are arranged throughout the area where sunlight is blocked or reduced by the decorative layer 4. The areas where sunlight is blocked or reduced by the decorative layer 4 are indicated by dots in Figure 2. Specifically, dummy cells 21 are arranged at both ends in the connection direction of the solar cell string 2 in the shingled connection (both ends in the left-right direction in Figure 1). This makes it possible to address the reduction in output caused by sunlight blocking or reduction in brightness by the decorative layer 4, regardless of which side in the connection direction of the shingled connection sunlight is blocked or reduced by the decorative layer 4.

In addition, if the direction of sunlight relative to the solar cell module 1 is fixed, i.e., if it is determined that sunlight will be blocked or dimmed by the decorative layer 4 on one side of the connection direction of the shingled connection, a dummy cell 21 may be placed at one end of the solar cell string 2 in the connection direction (one end in the left-right direction in Figure 1) related to the shingled connection.

The protective plate 3 is, for example, a glass plate. The thickness of the protective plate 3 is, for example, 2 mm or more and 8 mm or less. In the solar cell module 1 of this embodiment, the protective plate 3 is provided only on the front surface 22 of the solar cell string 2. In this case, a resin sheet 7 is provided on the back surface 23 of the solar cell string 2. The protective plate 3 may also be provided on both the front surface 22 and the back surface 23 of the solar cell string 2.

The decorative layer 4 is, for example, a coating formed on the surface 30 (the surface located on the light incident side) of the protective plate 3. Therefore, the decorative layer 4 can be an effective countermeasure against output reduction in solar cell modules 1 that use common techniques (painting) to enhance their appearance.

The decorative layer 4 is provided to improve the appearance of the solar cell module 1, for example, by hiding the electrical wiring around the solar cell string 2. Specifically, the decorative layer 4 is a coating film with a thickness of 5 μm to 50 μm. This coating film is formed, for example, by ceramic printing. The decorative layer 4 is a coating film that blocks incident light or transmits (dims) a certain amount of incident light. In the solar cell module 1 of this embodiment, the decorative layer 4 is a black coating film, but it may be a coating film of another color.

The decorative layer 4 is, for example, a solid coating covering a predetermined area. The decorative layer 4 may also be a coating formed by forming multiple light-shielding and light-transmitting areas adjacent to each other on the surface of the protective plate 3, thereby reducing light in the thickness direction through the combination of the light-shielding and light-transmitting areas. Specifically, the decorative layer 4 may be a coating applied in a dotted or meshed pattern over a predetermined area. The shape of each dot in a dotted coating or the mesh in a meshed coating is not particularly limited and can take various forms. In this case, the dotted or meshed coating ensures a sense of unity when viewed from the outside of the solar cell module 1, while partially allowing sunlight to enter through the coating, thereby reducing the shading rate and mitigating the effects of sunlight shading or light reduction caused by the decorative layer 4. The light transmittance of the coating can be adjusted by adjusting the area ratio between the light-shielding areas, where paint or other coating materials are arranged in a dotted or meshed pattern, and the light-transmitting areas, where no coating material is arranged. The decorative layer 4 may be a light-blocking material other than a coating, such as a black or other colored film.

The decorative layer 4 is disposed on the outer edge of the protective plate 3 and is a separate member from the frame 6, which is provided to shape and reinforce the solar cell module 1. Therefore, as will be described later, the shadow cast by the decorative layer 4 is completely different from the shadow cast by the frame 6.

The sealing material 5 is, for example, layered on each of the front surface 22 and back surface 23 of the solar cell string 2. The sealing material 5 is, for example, a resin layer. Furthermore, the sealing material 5 also covers the end surfaces (outer peripheries) of the solar cell string 2. Specifically, the sealing material 5 continuously covers the front surface 22, back surface 23, and end surfaces of the solar cell string 2.

Samples of the above solar cell module 1 were prepared in which the number of dummy cells 21 installed on one side of the solar cell string 2 in the connection direction for the shingled connection was varied from 0 to 3, and a simulation was performed to calculate the amount of power generated. In these solar cell modules 1, the width of the power generating cells 20 was 24 mm, and the thickness of the protective plate 3 (glass plate) was 6 mm. The solar cell module 1 was also installed at a 90-degree angle, facing south. Note that 90-degree installation means that the solar cell module 1 is installed at an angle of 90 degrees to the horizontal plane.

In this simulation, calculations were performed assuming that when direct or quasi-direct light is blocked by the decorative layer 4, the direct or quasi-direct light is attenuated by the proportion of light it receives on the dummy cell 21 or power-generating cell 20 located at the very end of one side (sun side) in the connection direction of the solar cell string 2. Note that the solar radiation used in the simulation was the average annual data for Fukuoka from the Annual Hourly Solar Radiation Database (METPV-11).

The results of this simulation showed that the annual power generation per 1 kW installed was 653 kWh when there were no dummy cells 21, 755 kWh when there was one dummy cell 21, 762 kWh when there were two dummy cells 21, and 763 kWh when there were three dummy cells 21. Thus, the results showed that by providing at least one dummy cell 21 on one side of the connection direction of the solar cell string 2 in a single connection, the power generation amount can be increased by approximately 16%.

Furthermore, in the solar cell module 1 described above, the shading or dimming of sunlight by the decorative layer 4 occurs inside the module, and therefore the decorative layer 4 does not cast a visually (externally) recognizable shadow on the solar cell module 1 (a shadow outside the module), such as a shadow cast by the frame 6. Therefore, the issue of reduced output from the solar cell module 1 due to the shading or dimming of sunlight by the decorative layer 4 (a "shadow that is completed within the module" that is difficult to discern visually from outside the module) has not received attention until now, and is a new issue discovered for the first time by the inventors of the present application.

Furthermore, the inventors of the present application were only able to estimate the extent of the impact of the decorative layer 4 on a year-round basis after actually performing the simulations described below. Therefore, even for a person skilled in the art, it would not be easy to arrive at the configuration of the combination of the decorative layer 4 (coating film) and dummy cells 21 according to this embodiment after performing such simulations.

The following describes a simulation to calculate the length of the portion of the solar cell module 1 that is shaded or dimmed by the decorative layer 4 (coating film) (the dimension in the connection direction of the solar cell string 2 in a shingled connection). In these solar cell modules 1, the width of the power generating cells 20 is 25 mm, and the thickness of the protective plate 3 (glass plate) is 6 mm. The solar cell modules 1 were also installed vertically (90 degrees) and faced south. For the solar radiation amount used in the simulation, normal data for Osaka from the Annual Hourly Solar Radiation Database (METPV-11) was used.

The simulation results are shown in Table 1 below. × indicates time periods when direct sunlight does not reach the module. Additionally, negative values indicate that sunlight is blocked or reduced on the west side of the coating, while positive values indicate that sunlight is blocked or reduced on the east side of the coating.

As a result of this simulation, for example, at 1:30 p.m. on June 20th in Osaka,
It was found that when a module with a 6 mm thick protective plate 3 on the light-receiving surface side is installed vertically facing south, a 10.7 mm wide area of sunlight is blocked or dimmed to the east of the coating. When sunlight is blocked or dimmed in this way, if a solar cell string 2 composed of electrically connected cells each 25 mm wide is placed closely to the coating (when the solar cell string 2 is composed only of power-generating cells 20), direct sunlight is blocked or dimmed in 42.8% of the area of the power-generating cells 20 placed closest to the coating, thereby reducing the power generation capacity of the entire module. On the other hand, when dummy cells 21 of the same dimensions as the power-generating cells 20 but not electrically connected to them are placed between the coating and the solar cell string 2 (when the solar cell string 2 includes dummy cells 21 as in the solar cell module 1), sunlight is not blocked or dimmed in the electrically connected power-generating cells 20, and therefore no reduction in power generation capacity occurs.

The solar cell module of the present invention is not limited to the above-described embodiments, and various modifications can of course be made without departing from the spirit of the present invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, or part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Furthermore, part of the configuration of one embodiment can be deleted.

In the solar cell module 1 of the above embodiment, dummy cells 21 were arranged throughout the entire portion of the solar cell string 2 where sunlight is blocked or reduced by the decorative layer 4. However, dummy cells 21 may be arranged in part of this portion, with a space (empty space) in the remaining portion. For example, the solar cell module 1 of FIG. 2 has two dummy cells 21. However, a space (empty space) may be provided in place of one of the two dummy cells 21. Note that a sealing material 5 is placed in this space. Furthermore, in the solar module 1 of the above embodiment, the dummy cells 21 were arranged in a position that did not overlap the decorative layer 4 in a planar view. However, a portion of the dummy cells 21 may be arranged in a position that overlaps the decorative layer 4 in a planar view. This configuration has the advantage of increasing the degree of freedom in the arrangement of each portion relative to the determined size (glass size) of the protective plate 3.

In addition, in the solar cell string 2 of the above embodiment, the size of each power generating cell 20 is the same, but they may be different. For example, the size (width dimension in the case of single-connected power generating cells 20) of the power generating cell 20 arranged near the dummy cell 21 can be made larger than the size of the other power generating cells 20. In this case, even if sunlight is blocked or reduced by the decorative layer 4 in a portion of the power generating cell 20 arranged near the dummy cell 21, the area of the light-receiving surface of this power generating cell 20 that is actually hit by light can be secured, so a decrease in output due to the influence of sunlight blocking or reduction in light by the decorative layer 4 is unlikely to occur.

In the above embodiment, the solar cell module 1 was installed with its main surface (light-receiving surface) facing upward, for example. However, it may also be attached to a vertical surface or a surface close to a vertical surface (for example, a surface inclined at 15° or less from the vertical), such as the exterior wall of a private home. In this case, the solar cell module 1 may be provided with a mounting portion (bracket, etc.) for mounting to a vertical surface. For example, the mounting portion is provided on the frame 6. In a solar cell module 1 equipped with a mounting portion, as long as the power generating cells 20 and the dummy cells 21 have the same shape at least in a plan view, when the solar cell module 1 is installed on a vertical surface using the mounting portion, there is no aesthetic problem even if the solar cell strings 2 in an easily visible position are visible through the protective plate 3.

In the solar cell string 2 of the above embodiment, the power generating cells 20 have an elongated shape, and multiple power generating cells 20 are connected in a single pattern. However, the shape of the power generating cells 20 may be a shape other than an elongated shape, such as a square plate, and the multiple power generating cells 20 may not be connected in a single pattern, but may be connected by wiring material.

1...Solar cell module, 2...Solar cell string, 3...Protective plate, 4...Decorative layer, 5...Sealant, 6...Frame, 7...Resin sheet, 11...Solar cell module, 12...Solar cell string, 20...Power generating cell, 21...Dummy cell, 22...Front surface, 23...Back surface, 30...Front surface, 120, 120a, 120b, 120c, 120d, 120e...Power generating cell

Claims (7)

a solar cell string;
a light-transmitting protective plate overlaid on the light incident side of the solar cell string;
a frame portion disposed on the outer edge of the protection plate;
a decorative layer formed on the light incident side surface of the protective plate, the decorative layer being a separate member from the frame portion and reducing or blocking light in a thickness direction;
The outer edge of the protective plate is rectangular having vertical and horizontal sides,
The frame portion is disposed along vertical and horizontal sides of the outer edge of the protection plate,
The decorative layer is disposed along only a vertical side of the outer edge of the protective plate,
the solar cell string includes a power generating cell that generates power by receiving light, and a dummy cell that is not electrically connected to the power generating cell and does not contribute to power generation of the solar cell string;
The dummy cell is disposed closer to the decorative layer than the power generating cell in a plan view. The solar cell module described in claim 1, wherein the power generating cell and the dummy cell have the same shape at least in plan view. The power generating cell has an elongated shape,
The solar cell module according to claim 1 or 2, wherein the solar cell string includes a plurality of the power generating cells connected in a single ring. The solar cell module described in claim 3, wherein the dummy cells are arranged at both ends of the solar cell string in the connection direction related to the single-ring connection. The solar cell module described in any one of claims 1 to 4, wherein the decorative layer is a coating film formed on the surface of the protective plate. The solar cell module described in claim 5, wherein the coating film is a coating film in which multiple light-blocking regions and multiple light-transmitting regions are formed adjacent to each other on the surface of the protective plate, and the combination of the light-blocking regions and the light-transmitting regions reduces light in the thickness direction. a solar cell string;
a light-transmitting protective plate overlaid on the light incident side of the solar cell string;
a decorative layer formed on the light incident side surface of the protective plate, the decorative layer reducing or blocking light in a thickness direction;
the solar cell string includes an elongated power generating cell that generates power by receiving light, and a dummy cell that is not electrically connected to the power generating cell and does not contribute to power generation of the solar cell string;
In the solar cell string, a plurality of the power generating cells are connected in a single connection,
The dummy cells are positioned closer to the decorative layer than the power generating cells in a planar view, and are arranged at both ends of the solar cell string related to the shingling connection in the connection direction, but are not arranged at both ends of the solar cell string related to the shingling connection in the direction perpendicular to the connection direction.