Solar cell

Abstract

To provide a flexible solar cell which can be installed on a bent installation surface while achieving high power generation efficiency by using a glass plate.SOLUTION: The solar battery module includes a plurality of solar battery bodies 10 each having a flexible photovoltaic power generation layer 12 and a flexible light-receiving side plate body layer 11a laminated on the light-receiving side of the photovoltaic power generation layer. The solar battery 1 has flexibility and is installed on a bent installation surface 2, wherein a light-receiving-side plate layer 11a is a glass plate having a plate thickness of 0.1 12a or less and laminated so as to cover a light-receiving-side 1mm of a photovoltaic power generation layer, and the solar battery bodies are arranged with a gap 15 having an interval 50 corresponding to a bending angle α of the installation surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flexible solar cell that can be installed on a curved installation surface. [Background technology]

[0002] In order to provide this type of conventional solar cell with flexibility and designability, Patent Document 1 below discloses the use of a resin film having a predetermined storage modulus as a first encapsulating layer laminated on a solar cell element. Patent Document 2 below also discloses a laminate having a resin sheet and a glass layer that can be used as an encapsulant for a solar cell module, and describes the use of a resin sheet made of a resin composition containing ethylene ionomer as a main component to improve transparency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-189466 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-188158 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for flexible solar cells that can be installed on curved surfaces, as disclosed in Patent Document 1. However, in this case, the solar cell element is sealed with a resin film, and the challenge is how to reduce the oxygen permeability and water vapor permeability of the resin film. In other words, to improve the power generation efficiency of solar cells, it is ideal to completely block the permeation of oxygen and water vapor, but it is extremely difficult to achieve a resin film with a transmittance comparable to that of a glass plate. Furthermore, while Patent Document 1 describes an evaluation test for installation on a curved surface with a curvature radius of 85 mm, it is not designed for installation on a curved surface. Patent Document 2 discloses the use of a glass layer as a sealing material for solar cell modules, but it is not flexible. Therefore, when using a glass plate as a sealing material, even a very thin glass plate will crack when bent, which is an issue.

[0005] The present invention has been proposed in consideration of the above circumstances, and its purpose is to provide a solar cell that uses glass plates to achieve high power generation efficiency, yet is flexible enough to be installed on a curved installation surface. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the solar cell of the present invention is a flexible solar cell that is installed on a curved installation surface and comprises a plurality of solar cell bodies, each having a flexible solar power generation layer and a flexible light-receiving side plate layer that is laminated on the light-receiving side of the solar power generation layer, wherein the light-receiving side plate layer is a glass plate that is laminated to cover the light-receiving surface of the solar power generation layer and has a plate thickness of 0.1 mm or less, and the solar cell bodies are arranged with a gap portion having a spacing that corresponds to the bending angle of the installation surface.

[0007] In the above configuration, the gap may be formed by a flexible protective layer disposed on both sides of the solar cell body in a thickness direction. Also, in the above configuration, the spacing of the gap may be set based on a minimum bending radius of the gap. [Effects of the Invention]

[0008] Since the solar cell of the present invention has the above-described structure, it can be made flexible while using a glass plate to achieve high power generation efficiency. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a vertical cross-sectional view schematically showing a solar cell according to one embodiment of the present invention. [Figure 2] 1(a) to 1(c) are diagrams each showing a schematic diagram of the solar cell, etc., to explain an example in which the solar cell is installed on the cover of a streetlight, which is the installation surface. 1(a) and 1(b) are plan views each showing a schematic diagram of an example of the solar cell, and 1(c) is a perspective view of the installation surface and the solar cell. [Figure 3] FIG. 1(a) is a side view showing the solar cell installed on a street light cover, and FIG. 1(b) is a cross-sectional view of the installation surface and the solar cell. [Figure 4] (a) to (c) are diagrams each showing a schematic representation of the solar cell, etc., to explain an example of installing the solar cell on a convex mirror, which is an installation surface. (a) is a perspective view showing the solar cell installed on a convex mirror, (b) is a plan view showing the solar cell, and (c) is an exploded perspective view showing the solar cell installed. [Figure 5] 1(a) to 1(c) are diagrams showing a schematic layer structure for explaining an example of a solar cell body that constitutes the solar cell. [Figure 6] 1(a) to 1(d) are diagrams for explaining a bending evaluation test conducted by the inventors, in which 1(a) is a plan view of a test sheet, 1(b) is a cross-sectional view taken along line X1-X1 of 1(a), 1(c) is a diagram for explaining the conditions of the bending test, and 1(d) is a table for explaining the results of the evaluation test. [Figure 7]1(a) to 1(d) are diagrams for explaining a bending evaluation test conducted by the inventor, in which 1(a) is a plan view of a test sheet, 1(b) is a cross-sectional view taken along line X2-X2 of 1(a), 1(c) is a diagram for explaining the conditions of the bending test, and 1(d) is a table for explaining the test results of the evaluation test. [Figure 8] (a) is a graph showing the relationship between the bending angle of the installation surface and the spacing of the gap, (b) to (e) are diagrams for explaining that the spacing of the gap is set based on the minimum bending radius of the gap, (b) and (c) are cross-sectional views of the solar cell, and (d) and (e) are diagrams for explaining how to calculate x from the bending angle of the installation surface. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that in some drawings, some of the detailed reference numerals used in other drawings are omitted. The solar cell 1 (module) according to this embodiment comprises a plurality of solar cell bodies 10 (cells), each having a photovoltaic layer 12 and a light-receiving-side plate layer 11a laminated on the light-receiving side of the photovoltaic layer 12, and is flexible enough to be installed on a curved installation surface 2. The light-receiving-side plate layer 11a is a glass plate laminated to cover the light-receiving surface 12a of the photovoltaic layer 12 and has a thickness of 0.1 mm or less. The solar cell bodies 10 are arranged with gaps 15a spaced apart according to the bending angle α of the installation surface 2. This will be described in detail below.

[0011] The solar cell according to this embodiment will be described with reference to Figures 1 to 4. Figure 1 is a vertical cross-sectional view that schematically shows a solar cell 1 according to this embodiment, Figures 2 and 3 show an example in which solar cells 1 (1A, 1B) are installed on the outer surface of a cover 30 of a street light 3, and Figure 4 shows an example in which solar cells 1 (1C, 1D) are installed on a convex mirror 4.

[0012] A solar cell 1 is a device that converts light energy into electricity and is configured in a stacked structure including multiple solar cell bodies 10, each having a photovoltaic layer 12, as shown in FIG. 1 and other figures. The photovoltaic layer 12 used here may be any flexible material, including silicon, compound, or organic materials. Specifically, it can be applied to amorphous silicon solar cells, dye-sensitized solar cells, organic thin-film solar cells, and perovskite solar cells. A perovskite-type photovoltaic layer 12 is preferable because it allows the solar cell body 10 to be thin and lightweight. The perovskite-type refers to a solar cell 12 that uses a perovskite layer made of an organic material with a unique crystalline structure known as a perovskite structure. The photovoltaic layer 12 can be extremely thin, measuring 10 μm or less. At least one surface of the photovoltaic layer 12 is a light-receiving surface 12a for receiving light. In the accompanying drawings, the upper side of the photovoltaic layer 12 is referred to as the light-receiving side, and the lower side is referred to as the installation side.

[0013] The solar cell 1 comprises a plurality of solar cell bodies 10 arranged side by side, each of which is covered with a protective layer 13 on both sides in the thickness direction and fixed in a sealed state. The solar cell bodies 10 are composed of individual separated cells, and the solar cell bodies 10 provided on one solar cell 1 are formed so that the area of ​​each cell is the same even though they have different shapes. Therefore, as shown in Figures 2(a), 2(b), and 4(b), the solar cell bodies 10 are formed according to the position of the bent portion 20 and the shape of the flat portion 21 of the installation surface 2, but the solar cell bodies 10 provided on one solar cell 1 are formed to have the same area. Adjacent solar cell bodies 10 are arranged with gaps 15 spaced apart, and gaps 15 are provided around the solar cell bodies 10. Of the gaps 15 provided around the solar cell body 10, gaps 15a arranged at the bent portion 20 are provided at intervals 50 corresponding to the bending angle α of the bent portion 20 (see Figure 3(b)). In the drawing, the gaps arranged in the bent portion 20 are indicated as 15a, and the other gaps are indicated as 15b.

[0014] The photovoltaic power generation layer 12 constituting the solar cell body 10 is flexible, but as shown in FIG. 3(b), the photovoltaic power generation layer 12 is installed on the flat portion 21 without spanning the bent portion 20, and the gap 15a is disposed in the bent portion 20. This configuration allows the solar cell 1 to be installed on an installation surface 2 having the bent portion 20, while broadening the versatility of what can be used for the photovoltaic power generation layer 12. The spacing 50 of the gap 15a is set according to the bending angle α of the bent portion 20 as described above, and is set based on the minimum bending radius of the gap 15a. A method for calculating the minimum dimension of the spacing 50 will be described later using a specific example and with reference to FIG. 8.

[0015] As shown in Figure 1 and other figures, the photovoltaic power generation layer 12 is configured to be slightly smaller than the light-receiving-side plate layer 11a and the installation-side plate layer 11b, and the photovoltaic power generation layer 12 is placed on the installation-side plate layer 11b, with the light-receiving-side plate layer 11a stacked on top of that. Interlayer gaps 14 formed around the photovoltaic power generation layer 12 are sealed with elastomer 16 (see the enlarged view of Figure 1). As described above, gaps 15 are provided between the solar cell bodies 10, and both sides of the solar cell body 10 are covered with protective layers 13, so elastomer 16 is provided in the gaps 15 between the protective layers 13 (see the enlarged view of Figure 1). Furthermore, the protective layer 13 and the light-receiving side plate layer 11a, the light-receiving side plate layer 11a and the solar power generation layer 12, the solar power generation layer 12 and the installation side plate layer 11b, and the installation side plate layer 11b and the protective layer 13 are each fixed with an adhesive (not shown).

[0016] While the configuration of the solar cell 1 is not particularly limited, FIGS. 2 and 3 show examples of solar cells 1A and 1B installed on a street light 3 as an example of how the solar cell 1 is installed. FIGS. 2(a) and 2(b) show plan views of the solar cells 1A and 1B before they are installed on the cover 30 of the street light 3. The street light 3 in the figure uses solar power to light a lamp 32. The umbrella-shaped cover 30 that covers the lamp 32 is composed of surfaces with different inclination angles, so two types of sheet-like solar cells 1A and 1B are used. The solar cell 1A in FIG. 2(a) is installed on a smaller installation surface 2 at a steeper angle (larger inclination angle) than the installation surface 2 of the solar cell 1B in FIG. 2(b). The solar cell 1A in FIG. 2(a) is formed in a substantially square shape, with a through-hole 17 in the center that is inserted into a spire 31 formed above the cover 30. The solar cell body 10 is formed in a substantially right-angled isosceles triangle shape, and four solar cells 10 having the same area are combined to form a substantially square shape. Gap 15a of solar cell 1A is formed according to the bending angle of bent portion 20 of installation surface 2 on the spire portion 31 side. Solar cell 1B in FIG. 2(b) is formed in a substantially square shape larger than solar cell 1A, and has a through-hole 17 in the center that passes through spire portion 31 and installation surface 2 on which solar cell 1A is installed. Solar cell body 10 is formed in a substantially trapezoidal shape, and eight solar cell bodies having the same area are combined to form a substantially square shape. Gap 15a of solar cell 1B is also formed according to the bending angle α of bent portion 20 of installation surface 2 below installation surface 2 on which solar cell 1A is arranged.

[0017] No solar cell 10 is provided in gaps 15a, 15b provided between solar cell bodies 10, and gaps 15a, 15b are composed of flexible protective layers 13, 13 and elastomer 16. Furthermore, spacing 50 of gap 15a is provided according to bending angle α of installation surface 2, so solar cells 1A, 1B can be sufficiently bent in gap 15a along bending angle α of bending portion 20 of installation surface 2. Therefore, as shown in FIG. 3(b) and other figures, solar cells 1A, 1B can be installed on installation surface 2 having bending portion 20 and flat portion 21 without creating a large gap.

[0018] The light-receiving-side plate layer 11a covers the entire light-receiving surface 12a of the photovoltaic layer 12 and is arranged so that the light-receiving-side plate layer 11a does not reach the gap 15. A flexible glass plate with a thickness of 0.1 mm or less is used as the light-receiving-side plate layer 11a. In other words, neither the photovoltaic layer 12 nor the light-receiving-side plate layer 11a, which is made of glass, is arranged in the gaps 15a and 15b. The thickness of the glass plate constituting this light-receiving-side plate layer 11a is preferably 0.1 mm or less, more specifically, 20 μm to 100 μm. The properties of the glass plate are not particularly limited, but a glass plate formed into a film by overflow molding may be used. A glass plate with high light transmittance, heat resistance sufficient for outdoor use under sunlight, and dimensional stability (low thermal expansion and shrinkage) are preferred.

[0019] The elastomer 16 used to seal the interlayer gap 14 and gaps 15a and 15b between the photovoltaic layer 12 and the light-receiving side plate layer 11a is preferably an acrylic, silicone, polyolefin, polyurethane, or ethylene vinyl acetate elastomer, which has excellent adhesive properties, thermal expansion absorption, and shock absorption. In this embodiment, the elastomer 16 functions as both a sealant and an adhesive, and is preferably elastic enough not to impair the flexibility of the solar cell 1. Furthermore, the elastomer 16 used to seal the interlayer gap 14 between the photovoltaic layer 12 and the light-receiving side plate layer 11a, as well as the adhesives used to bond the protective layer 13 and the light-receiving side plate layer 11a and the light-receiving side plate layer 11a and the photovoltaic layer 12, must be transparent enough to allow light to pass through. The water vapor permeability of polyurethane-based adhesives is approximately 37 g / m²·day. The adhesive used to bond the photovoltaic layer 12 to the installation-side plate layer 11b and the installation-side plate layer 11b to the protective layer 13 does not need to be transparent, but it goes without saying that the same adhesive as that used on the light-receiving side may be used. Furthermore, the adhesives used to bond the elastomer 16 to each layer may be different or the same.

[0020] The protective layer 13 is disposed on the outermost layer of the solar cell 1, covering the entire solar cell body 10. It protects the solar cell body 10 and prevents cracking and shattering of the light-receiving-side plate layer 11a, which is made of a glass plate. The protective layer 13 disposed on the light-receiving side is made of a material that is transparent enough to transmit light and convert it into electricity efficiently, and is impact-resistant enough to absorb the thermal expansion difference with the photovoltaic power generation layer 12, maintaining interlayer adhesion. The protective layer 13 is made of, for example, a film made of a transparent and flexible synthetic resin material. Specific examples of suitable synthetic resin materials include low-density polyethylene (LDPE), high-density polyethylene (HDPE), unstretched polypropylene (CPP), oriented polypropylene (OPP), polyethylene terephthalate (PET), cycloolefin polymer (COP), elastic fluorine film, and urethane film. The thickness of the protective layer 13 is not particularly limited, but is preferably 20 μm to 500 μm. The outer periphery of the protective layer 13 may be welded with an adhesive or by heat sealing to prevent peeling due to deterioration.

[0021] According to the above configuration, a thin glass plate of 0.1 mm or less, which is almost impermeable to oxygen and water vapor, is laminated on the light-receiving side of the photovoltaic layer 12, resulting in a solar cell 1 (1A, 1B) with high photovoltaic efficiency. Perovskite-type photovoltaic layers 12 in particular have a problem in that their photovoltaic efficiency is significantly reduced by oxygen and humidity. However, using a perovskite-type material for the photovoltaic layer 12 according to this embodiment allows for long-term gas barrier properties and thin and flexible structures, making it suitable. While the overall thickness of the solar cell body 10 is not particularly limited, the configuration of this embodiment allows for a thickness of 0.01 mm to 1 mm. Furthermore, because a gap 15a is provided between the solar cell bodies 10, with a spacing 50 corresponding to the bending angle α of the installation surface 2, the solar cell 1 can be installed on a flexible installation surface 2 having a bending portion 20, even if it includes a glass plate. Furthermore, the solar cell body 10 is sealed with a protective layer 13, which prevents scratches and cracks on the glass plate and protects the light-receiving-side plate layer 11a. For example, a glass plate with a thickness of 30 μm to 50 μm, which is less than 100 μm, can be bent, but it tends to be weak and prone to cracks when subjected to impact.However, since the glass plate that is the light-receiving side plate layer 11a is covered with protective layer 13, a solar cell body 10 that can withstand impact can be constructed.

[0022] Furthermore, if the interlayer gap 14 and gap portion 15 that occur between the solar power generation layer 12 and the light-receiving side plate layer 11a are sealed with a transparent and elastic elastomer 16, the solar cell 1 (1A, 1B) can be made flexible while not affecting the photovoltaic efficiency.

[0023] 4(a) to 4(c) show examples of solar cells 1C and 1D installed on a convex mirror 4 as an example of how the solar cell 1 is installed. FIG. 4(b) shows a plan view of the solar cells 1C and 1D. The convex mirror 4 has an electric heater 45 built into the back of the mirror 41, and the heater 45 is configured to be driven by solar power generation. The mirror 41 and heater 45 are attached to the front and back of a mounting plate 44. If the surface to which the mirror 41 is attached is one surface 44a, multiple planar heaters 45 are provided on the other surface 44b of the mounting plate 44. The installation surface 2 on the other surface 44b has a roughly cross-shaped concavo-convex shape. A hood 40 is provided above the mirror 41 as a canopy to protect it from rain and dirt, and the mirror 41 is attached to a support 42 with mounting brackets 43.

[0024] The solar cell 1 installed on the convex mirror 4 is composed of a single sheet body, including a solar cell 1C that is circular in plan view and a strip-shaped solar cell 1D that is installed on the upper surface of the hood 40. The central portion of the circular solar cell 1C has a through-hole 17 that provides space for arranging a mounting bracket 43. The solar cell body 10 installed on the solar cells 1C and 1D is formed into a stepped shape 10A that combines square shapes in plan view, an approximately square shape 10B, or a curved, bow-like strip shape 10C that matches the shape of the hood 40. Although all of these have different shapes, they are configured to have the same area. The gaps 15b of the solar cells 1C and 1D are appropriately set and may be arranged with almost no gaps if the installation surface 2 is not curved, but the gaps 15a arranged in the bending portion 20 are formed according to the bending angle α of the installation surface 2.

[0025] When solar cells 1C and 1D are installed on a convex mirror 4 as shown in FIG. 4(a), conventionally, the other surface 44b is uneven due to the heater 45, so the solar cells are often installed only on the outer surface of the hood 40. However, according to the solar cells 1C and 1D of this embodiment, even if there is a bent portion 20 extending from the mounting plate 44 to the hood 40 and a bent portion 20 formed by the heater 45 (see FIG. 4(c) for both), the solar cells 1C and 1D can be installed by bending them. This allows the installation area of ​​the solar cell body 10 to be increased, thereby increasing the amount of power generated. It goes without saying that the example shown in FIG. 4 also achieves the same effects as the examples shown in FIGS. 1 to 3, and the basic structure of the solar cell 1 is the same.

[0026] Next, with reference to FIG. 5, an example of a solar cell body 10 constituting the solar cell 1 will be described. First, FIG. 5(a) shows an example in which both the light-receiving-side plate layer 11a and the installation-side plate layer 11b are glass plates. In this case, the light-receiving-side plate layer 11a and the installation-side plate layer 11b are made of the same plate thickness of 0.1 mm or less. Because glass plates have nearly zero water vapor permeability and oxygen permeability and high gas barrier properties, the protective layers 13 arranged on the light-receiving side and the installation side do not need to consider gas barrier properties such as water vapor permeability and oxygen permeability. This has the advantage of providing a wider range of material options for the protective layer 13. To ensure efficient light reception, it is desirable to use a highly transparent material for the protective layer 13 arranged on the light-receiving side. Of course, both protective layers 13 may be made of highly transparent materials.

[0027] Figure 5(b) shows an example in which the light-receiving-side plate layer 11a is a glass plate with a thickness of 0.1 mm or less, there is no installation-side plate layer 11b, and a protective layer 13 with high gas barrier properties is arranged on the installation side of the photovoltaic layer 12. In this case, like the example of Figure 5(a), there is no need to consider the water vapor permeability, oxygen permeability, or gas barrier properties of the protective layer 13 arranged on the light-receiving side, and since there is no installation-side plate layer 11b, it is possible to further reduce the thickness of the solar cell 1. In this case, it is preferable that the installation-side protective layer 13 has low water vapor permeability and oxygen permeability and high gas barrier properties.

[0028] Figure 5(c) is an example that can be considered a modification of Figure 5(a) or Figure 5(b). This example has the same light-receiving-side plate layer 11a and protective layers 13 on both the top and bottom surfaces (both in the thickness direction), but differs from the above examples in that it includes a flexible resin plate material as the installation-side plate layer 11b. Examples of resin plate materials include polycarbonate (PC), acrylic resin (PMMA), polyethylene terephthalate (PET), copolymer polyester (PETG), polyvinyl chloride (PVC), cyclic olefin polymer (COC, COP), and polyethylene (PE). The thickness of the installation-side plate layer 11b may be selected depending on the installation location and is not particularly limited, but a thin thickness allows for thinner solar cells 1.

[0029] Next, with reference to FIGS. 6 and 7 , a bending evaluation test of a glass plate conducted by the inventors will be described. In this evaluation test, sheet bodies 100 and 100A simulating solar cells were prepared. Both sheet bodies 100 and 100A had the same laminated structure, and glass plates and films of the same thickness were used. The evaluation was conducted to determine the difference and effect on the bendability of the glass plate depending on whether or not there was a gap 150. The bendability was evaluated by bending the sheet body 100 or 100A at approximately its center, maintaining the bent state with a pair of clamping plates 300, 300, and checking for cracks in the glass plate after release. The bending gap L (see FIGS. 6(c) and 7(c)) of the sheet body 100 or 100A was varied to 50 mm, 40 mm, 30 mm, 20 mm, 10 mm, and 5 mm. The evaluation was conducted while maintaining a constant speed for bending the approximately center portion of the sheet body 100 or 100A.

[0030] Each of the sheets 100 and 100A was approximately rectangular, with sides measuring approximately 20 cm. A 150 μm-thick polyethylene terephthalate protective film 130, equivalent to the protective layer 13, was disposed on the outermost surface of each of the sheets 100 and 100A in the thickness direction. A 38 μm polyethylene terephthalate film 120 was disposed on both thickness directions of a 50 μm glass plate layer 110 to form a glass layer 101 equivalent to the solar cell 10. The protective film 130 and the film 120 were bonded together with an adhesive 200. The adhesive 200 was an EVA (ethylene vinyl acetate) adhesive that becomes transparent when heated. The glass plate layer 110 was made of thin glass, G-Leaf (registered trademark), manufactured by Nippon Electric Glass Co., Ltd.

[0031] The sheet body 100 has one glass layer 101 formed slightly smaller than the approximately rectangular protective film 130, while the sheet body 100A has two glass layers 101 within a pair of approximately rectangular protective films 130, with a gap D3 of 10 mm between the glass layers 101 (see Figure 7(b)).

[0032] When a bending evaluation test was performed on the sheet body 100, as shown in the table in FIG. 6(d), no cracks were observed in the glass layer 101 when the bending gap L was between 50 mm and 20 mm. However, when the bending gap L was set to 10 mm, cracks were observed. Therefore, when the bending gap L was checked in 1 mm increments from 20 mm, it was found that cracks occurred when the bending gap L was 13 mm. The radius of curvature of the sheet body 100 at this time was R6.5 mm. On the other hand, when a bending evaluation test was performed on the sheet body 100A, as shown in the table in FIG. 7(d), no cracks were observed in the glass layer 101 when the bending gap L was between 50 mm and 5 mm. This evaluation test revealed that when the gap portion 150 was set to 10 mm, no cracks occurred even when the sheet was bent up to a bending gap L of 5 mm (radius of curvature R2.5 mm).

[0033] From the above, it was found that if a 50 μm glass plate is protected with a protective film as described above, it can maintain flexibility without cracking even if the bending gap L is 20 mm (curvature radius R 10 mm). In addition, if gap 150 is provided between the glass plates, it was found that no cracks will occur even if the bending gap L is 5 mm, so it was demonstrated that if this structure is applied to a solar cell module, it can be made to have sufficient flexibility.

[0034] Next, with reference to FIG. 8, we will explain how to set the spacing 50 of the gap 15a based on the bending angle α of the installation surface 2. FIG. 8(a) is a graph showing the dimensions of the spacing 50 calculated based on the minimum bending radius of the gap 15a. FIG. 8(a) is a graph calculated based on the evaluation test of the sheet member 100A shown in FIG. 7. Here, the "minimum bending diameter" refers to the bending gap L of the sheet member 100 at the limit at which the sheet member 100 can be bent without cracks appearing, and the "minimum bending radius" refers to the radius of curvature of the sheet member 100 at the limit at which the sheet member 100A can be bent without cracks appearing. In the evaluation test described above, the bending gap L at the limit at which the sheet member 100A can be bent without cracks appearing was 5 mm. In other words, the minimum bending diameter and minimum bending radius of the sheet member 100A can be said to be 5 mm and 2.5 mm, respectively. From this, the circumference length calculated by multiplying the minimum bending diameter (5 mm) by 3.14 is calculated as 15.7, and by halving this, the spacing 50 dimension of the gap 15a can be calculated as "7.85". When the spacing 50 is 7.85 mm, the bending angle α can be said to be 180 degrees, and the equation y=0.0436x can be derived by setting the vertical axis y to 7.85 mm and the horizontal axis x to 180 degrees.

[0035] 8(d) is a diagram illustrating a method for calculating the distance 50 when the bending angle α of the bending portion 20 is 150 degrees. When the bending angle α is 150 degrees, x is 180 degrees - 150 degrees = 30 degrees, so y can be calculated as y = 0.0436 × 30 degrees = 1.3 mm. Therefore, if the distance 50 of the gap 15a disposed in the bending portion 20 is set to 1.3 mm or more, the solar cell 1 can be installed without any problems on the installation surface 2 where the bending angle of the bending portion 20 is 150 degrees.

[0036] 8(e) is a diagram for explaining how to calculate the gap 50 dimension when the bending angle α of the bending portion 20 is 45 degrees. When the bending angle α is 45 degrees, x is 180 degrees - 45 degrees = 135 degrees, so y can be calculated as y = 0.0436 × 135 degrees = 5.886 mm. Therefore, if the gap 50 dimension of the gap portion 15a arranged in the bending portion 20 is set to approximately 5.9 mm or more, the solar cell 1 can be installed without any problems on the installation surface 2 where the bending angle of the bending portion 20 is 45 degrees.

[0037] The above calculation formula differs depending on the minimum bending radius of the gap 15, and the minimum bending radius of the gap 15 differs depending on the type and thickness of the film and adhesive that constitute the protective layer 13 used in the gap 15.

[0038] The configurations and structures of the solar cells 1, 1A-1D, and solar cell body 10 according to the above embodiments are not limited to those described above. The protective layer 13 may be configured by laminating multiple layers, and the light-receiving side plate layer 11a may be configured with a film layer in addition to a glass plate. The configurations of the modules that make up the solar cell 1 and the photovoltaic layer 12 that make up the solar cell body 10 are not limited to the shapes and numbers shown in the drawings, and are formed according to the shape and configuration of the installation surface 2 on which the solar cell 1 is installed. The solar cell 1 according to the above embodiments can be installed on an installation surface 2 that has a spherically curved flat portion 21 and a bent portion 20, or on a stepped installation surface 2. [Explanation of symbols]

[0039] 1. Solar cells 10 Solar cell body 11a Light-receiving side plate layer 12 Photovoltaic layer 12a Photosensitive surface 13 Protective layer 15 Gap 50 intervals α bending angle

Claims

1. A flexible solar cell includes a plurality of solar cell assemblies, each having a flexible photovoltaic layer and a flexible light-receiving side plate layer laminated on the light-receiving side of the photovoltaic layer, and is installed on a curved installation surface, the light-receiving side plate layer is a glass plate having a thickness of 0.1 mm or less and is laminated so as to cover the light-receiving surface of the photovoltaic layer; The solar cell is characterized in that the solar cell bodies are arranged with a gap therebetween having a distance corresponding to the bending angle of the installation surface.

2. In claim 1, The solar cell, wherein the gap is formed by a flexible protective layer disposed on both sides of the solar cell body in the thickness direction.

3. In claim 2, The solar cell, wherein the spacing of the gap is set based on a minimum bending radius of the gap.

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