Solar cell

Abstract

Provided is a flexible solar cell (1) which comprises a plurality solar cell bodies (10) that each have a flexible photovoltaic power generation layer (12) and a flexible light-receiving side plate layer (11a) that is laminated on the light-receiving side of the photovoltaic power generation layer and which is installed on a curved installation surface (2), said solar cell being characterized in that: the light-receiving side plate layer (11a) is a glass plate that is laminated so as to cover a light-receiving surface (12a) the photovoltaic power generation layer and that has a thickness of not more than 0.1 mm; and the solar cell bodies (10) are disposed so as to provide a gap part (15) therebetween with a spacing (50) in accordance with the angle α of curvature of the installation surface (2).

Description

solar cells

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

[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.

[0003] JP 2016-189466 A JP 2016-188158 A

[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, Patent Document 1 describes an evaluation test for installation on a curved surface with a curvature radius of 85 mm, but 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 the glass layer is not flexible. Therefore, when a glass plate is used 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.

[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 gaps that are spaced apart according 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.

[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.

[0009] 1A to 1C are schematic longitudinal cross-sectional views of a solar cell according to one embodiment of the present invention. (a) to (c) are schematic views of the solar cell and other components to illustrate an example in which the solar cell is installed on a streetlight cover, which is an installation surface. (a) and (b) are plan views of an example of the solar cell, and (c) is a perspective view of the installation surface and the solar cell. (a) is a side view of the solar cell installed on a streetlight cover, and (b) is a cross-sectional view of the installation surface and the solar cell. (a) to (c) are schematic views of the solar cell and other components to illustrate an example in which the solar cell is installed on a convex mirror, which is an installation surface. (a) is a perspective view of the solar cell installed on a convex mirror, (b) is a plan view of the solar cell, and (c) is an exploded perspective view to illustrate the installation state of the solar cell. (a) to (c) are schematic views of the layer structure to illustrate an example of a solar cell body constituting the solar cell. (a) to (d) are figures for explaining a bending evaluation test conducted by the inventors, where (a) is a plan view of a test sheet, (b) is a cross-sectional view taken along line X1-X1 in (a), and (c) is a diagram for explaining the conditions of the bending test. (d) is a table for explaining the results of the evaluation test. (a) to (d) are figures for explaining a bending evaluation test conducted by the inventors, where (a) is a plan view of a test sheet, (b) is a cross-sectional view taken along line X2-X2 in (a), and (c) is a diagram for explaining the conditions of the bending test. (d) is a table for explaining the results of the evaluation test. (a) is a graph showing the relationship between the bending angle of the installation surface and the spacing of the gaps, (b) to (e) are figures for explaining that the spacing of the gaps is set based on the minimum bending radius of the gaps, (b) and (c) are cross-sectional views of the solar cell, and (d) and (e) are figures for explaining how to calculate x from the bending angle of the installation surface.

[0010] An embodiment of the present invention will be described below with reference to the accompanying drawings. Note that in some figures, some detailed reference numerals used in other figures are omitted. A solar cell 1 (module) according to this embodiment includes 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. The solar cell body 10 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. A detailed description will be given 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 showing 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, organic, and other materials. Specifically, amorphous silicon solar cells, dye-sensitized solar cells, organic thin-film solar cells, and perovskite solar cells can be used. Among these, 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 having a unique crystalline structure known as a perovskite structure as the photovoltaic layer 12. 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 constitute 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 if they have different shapes. Therefore, as shown in FIGS. 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 located at the bent portion 20 are provided with a spacing 50 corresponding to the bending angle α of the bent portion 20 (see FIG. 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 layer 12 constituting the solar cell body 10 is flexible, but as shown in FIG. 3( b ), the photovoltaic layer 12 is installed on the flat portion 21 without spanning the bent portion 20, and the gap 15 a 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 layer 12. The spacing 50 of the gap 15 a 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 15. A method for calculating the minimum dimension of the spacing 50 will be described later based on a specific example and with reference to FIG. 8 .

[0015] As shown in Figure 1 and other figures, the photovoltaic layer 12 is slightly smaller than the light-receiving-side plate layer 11a and the installation-side plate layer 11b. The photovoltaic layer 12 is placed on the installation-side plate layer 11b, and the light-receiving-side plate layer 11a is layered on top of that. Interlayer gaps 14 formed around the photovoltaic layer 12 are sealed with elastomer 16 (see the enlarged view in 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 in Figure 1). Furthermore, the protective layer 13 and the light-receiving side plate layer 11a, the light-receiving side plate layer 11a and the photovoltaic layer 12, the photovoltaic 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, Figures 2 and 3 show examples of solar cells 1A and 1B installed on a street light 3 as an example of solar cell 1 installation. Figures 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 covering the lamp 32 is composed of surfaces with different inclination angles, so two types of sheet-shaped solar cells 1A and 1B are used. The solar cell 1A in Figure 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 Figure 2(b). The solar cell 1A in Figure 2(a) is formed in an approximately square shape, and a through-hole 17 is provided in the center for insertion of a spire 31 formed above the cover 30. The solar cell body 10 is formed in an approximately right-angled isosceles triangle shape, and four solar cells 10 having the same area are combined to form an approximately 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 having 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 having high light transmittance, heat resistance sufficient for outdoor use under sunlight, and dimensional stability (low thermal expansion and shrinkage) is 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 preferably functions as both a sealant and an adhesive and has elasticity that does not 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, are required to be transparent enough to not impede light transmission. 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 the light-receiving side plate layer 11a, which is made of a glass plate, from cracking or shattering. The protective layer 13 disposed on the light-receiving side is made of a material that is transparent enough to transmit light and efficiently convert it into electricity, absorbs the thermal expansion difference with the photovoltaic layer 12, maintains interlayer adhesion, and is impact-resistant. The protective layer 13 is typically made of a film made of a transparent, 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 is advantageous because it maintains gas barrier properties for a long period of time and allows for thin and flexible construction. 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 having 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 the protective layer 13, it is possible to construct a solar cell body 10 that can withstand impacts.

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

[0023] Figures 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. Figure 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 unevenness. 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 mounting hardware 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, with solar cells 1C and 1D according to this embodiment, solar cells 1C and 1D can be installed in a bent state even with the bent portion 20 extending from the mounting plate 44 to the hood 40 and the bent portion 20 formed by the heater 45 (see FIG. 4(c) for both). This allows for a larger installation area for the solar cell body 10, thereby increasing the amount of power generated. It goes without saying that the example shown in FIG. 4 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, referring 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 almost 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 efficiently receive light, 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 be one with 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 thicknesswise), 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 the gap 150 was present. 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 substantially constant speed when bending the sheet body 100 or 100A at approximately its center.

[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 G-Leaf (registered trademark) thin glass 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 if the gap portion 150 was set to 10 mm, no cracks would occur even when the sheet body was bent 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 is possible to maintain flexibility that prevents cracks from occurring even when the bending gap L is 20 mm (radius of curvature R 10 mm). In addition, it was found that if gap 150 is provided between the glass plates, cracks do not occur even when the bending gap L is 5 mm, so it was demonstrated that when 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 above evaluation test, the limit bending gap L 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 spacing 50 dimension 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 spacing 50 dimension of the gap 15a arranged 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 illustrating a method for calculating 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 0.0436 x 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 varies depending on the minimum bending radius of the gap portion 15, and the minimum bending radius of the gap portion 15 varies depending on the type and thickness of the film and adhesive that constitute the protective layer 13 used in the gap portion 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.

[0039] REFERENCE SIGNS LIST 1 solar cell 10 solar cell body 11a light-receiving side plate layer 12 photovoltaic power generation layer 12a light-receiving surface 13 protective layer 15 gap 50 spacing α bending angle

Claims

1. A flexible solar cell that is installed on a curved installation surface and comprises multiple solar cell bodies, each having a flexible photovoltaic layer and a flexible light-receiving side plate layer laminated on the light-receiving side of the photovoltaic layer, wherein the light-receiving side plate layer is a glass plate with a thickness of 0.1 mm or less that is laminated to cover the light-receiving surface of the photovoltaic layer, and wherein the solar cell bodies are arranged with gaps that are spaced apart according to the bending angle of the installation surface.

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

3. A solar cell according to claim 2, wherein the spacing of the gap is set based on the minimum bending radius of the gap.

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