Installation structure of flexible solar cell

Abstract

The purpose of the present invention is to provide an installation structure of a flexible solar cell that exhibits high safety even when exposed to strong wind. The present invention is an installation structure of a flexible solar cell, the structure including: an installation surface having a projection part continuous in one direction; a flexible solar cell disposed on a surface having the projection part of the installation surface; a fixing member for fixing the flexible solar cell by sandwiching the same between the fixing member and the projection part; and an easily deformable member disposed between the projection part and the flexible solar cell. The easily deformable member is sandwiched, together with the flexible solar cell, between the fixing member and the projection part, and the compressive strength of the easily deformable member is 0.5-400 MPa.

Description

Flexible solar panel installation structure

[0001] This invention relates to an installation structure for flexible solar cells.

[0002] Traditionally, rigid solar panels made of silicon semiconductors have been widely used as solar cells. However, conventional solar panels have a certain weight, making them unsuitable for installation on some structures with low load-bearing capacity, or they cannot be installed on areas with low load-bearing capacity even on suitable installation surfaces, thus hindering the effective utilization of the installation surface area. Therefore, in recent years, flexible solar cells using heat-resistant polymer materials such as polyimide and polyester, or metal foil as base materials, have been attracting attention. Flexible solar cells have advantages such as ease of transportation and installation due to their thinness and light weight, and resistance to impact. Flexible solar cells using flexible solar cells can be installed even on uneven installation surfaces, conforming to the surface. (For example, Patent Document 1)

[0003] International Publication No. 2023 / 182435

[0004] When installing flexible solar cells on an uneven surface, the method of installing them along the contours of the surface, as described in Patent Document 1, is effective from the standpoint of maximizing the power generation area. However, while this method of installing flexible solar cells along the contours of the surface increases the power generation area, it has the problem of poor maintainability, such as the replacement of the flexible solar cells. Typically, the building materials and structures that serve as the installation surface for flexible solar cells have a longer lifespan than the flexible solar cells themselves, so it is expected that the flexible solar cells will need to be replaced when they reach the end of their lifespan. In this case, if the flexible solar cells are installed along the contours, the replacement work becomes complicated, reducing maintainability. Therefore, a method of installing flexible solar cells by stretching them over the recesses has been considered to facilitate maintenance. However, when flexible solar cells are installed by stretching them over the recesses, when wind blows into the space between the flexible solar cell and the recess, deformation such as bending and vibration occurs in the flexible solar cell. Repeated deformation can lead to damage to the flexible solar cell, breakage of wiring, and damage to the installation surface. One possible solution to this problem is to firmly fix the flexible solar cells in place. While this would reduce deformation caused by wind, the flexible solar cells could still be damaged, and there is a need for a flexible solar cell installation structure that offers greater safety against strong winds.

[0005] The present invention aims to provide a highly safe installation structure for flexible solar cells, even when exposed to strong winds.

[0006] The present invention relates to an installation structure for a flexible solar cell, comprising: an installation surface having a convex portion continuous in one direction; a flexible solar cell disposed on the surface of the installation surface having the convex portion; a fixing member that secures the flexible solar cell by sandwiching it between the convex portion; and a deformable member disposed between the convex portion and the flexible solar cell, wherein the deformable member is sandwiched together with the flexible solar cell between the fixing member and the convex portion, and the compressive strength of the deformable member is 0.5 MPa or more and 400 MPa or less. The present invention will be described in detail below.

[0007] According to the present invention, it is possible to provide a flexible solar cell installation structure that offers high safety even when exposed to strong winds.

[0008] This is a cross-sectional view of a conventional flexible solar cell installed on a mounting surface having a protrusion. This is a schematic cross-sectional view illustrating an example of the installation structure of the flexible solar cell of the present invention. This is a schematic cross-sectional view illustrating yet another example of the installation structure of the flexible solar cell of the present invention. This is a schematic cross-sectional view illustrating an example of a flexible solar cell and an easily deformable member in the installation structure of the flexible solar cell of the present invention. This is a top view of Figure 4. This is a schematic cross-sectional view illustrating yet another example of a flexible solar cell and an easily deformable member in the installation structure of the flexible solar cell of the present invention. This is a schematic cross-sectional view illustrating yet another example of a flexible solar cell and an easily deformable member in the installation structure of the flexible solar cell of the present invention.

[0009] The present invention will be described in more detail below with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0010] (Embodiment 1) Figure 1 shows a cross-sectional view of a conventional flexible solar cell installed on a mounting surface having a protrusion. As shown in Figure 1, when a conventional flexible solar cell 1 is installed on a mounting surface having a protrusion 2, such as a corrugated metal roof, the flexible solar cell 1 is fixed by sandwiching the fixing member 3 between the protrusion 2 while the flexible solar cell 1 is stretched, from the viewpoint of maintainability. On the other hand, with the conventional installation structure, the flexible solar cell 1 can deform due to wind, and repeated deformation can damage the flexible solar cell 1. Also, if the flexible solar cell 1 is blown away by strong winds, the protrusion 2 may be damaged. One way to solve this problem is to suppress the deformation of the flexible solar cell 1 by fixing the fixing member 3 with strong force after the flexible solar cell 1 is stretched tightly. However, even if the flexible solar cell 1 is firmly fixed, although deformation due to wind is suppressed, the flexible solar cell 1 can still be damaged. Therefore, the inventors investigated the cause of damage to the flexible solar cell 1 when the flexible solar cell 1 is firmly fixed, and found that the cause is the concentration of force on a specific part of the flexible solar cell 1. When wind blows onto the firmly fixed flexible solar cell 1, a force is applied to the contact area between the flexible solar cell 1 and the fixing member 3. Furthermore, since the flexible solar cell 1 is also subjected to tension from its fixing, an even stronger force is applied to the contact area. While the flexible solar cell 1 does not deform, it becomes more susceptible to damage while fixed. Additionally, while damage to the flexible solar cell 1 poses a risk of electrical leakage, a firmly fixed flexible solar cell 1 exhibits minimal deformation and appears normal, making it difficult to detect damage. As a result, suppressing deformation to prevent damage to the flexible solar cell sometimes actually increases the risk.

[0011] Figures 2 and 3 show schematic cross-sectional views illustrating an example of the installation structure for the flexible solar cell of the present invention. As shown in Figure 2, the installation structure for the flexible solar cell of the present invention comprises an installation surface having a convex portion 2 that is continuous in one direction, a flexible solar cell 1 positioned on the surface of the installation surface having the convex portion 2, a fixing member 3 that secures the flexible solar cell 1 by sandwiching it between the convex portion 2, and a deformable member 4 positioned between the convex portion 2 and the flexible solar cell 1. The deformable member 4 is sandwiched together with the flexible solar cell 1 between the fixing member 3 and the convex portion 2. By providing the deformable member 4, when a strong force is applied to the fixing part of the flexible solar cell 1 due to strong winds, the deformable member 4 deforms and shifts in the planar direction (a direction perpendicular to the thickness direction), and the position of the flexible solar cell 1 also shifts accordingly. As a result, a large force is not applied to one location on the flexible solar cell 1 for a long period of time, so that the deformation of the flexible solar cell 1 due to strong winds is kept within a certain range and damage can be suppressed. Furthermore, since the easily deformable member 4 acts as a cushion when sandwiched between the flexible solar cell 1 and the protrusion 2, the force from the fixing member 3 and the force from the wind are appropriately dispersed, thus further reducing damage to the flexible solar cell 1. Moreover, by sandwiching the easily deformable member 4 between the protrusion 2 and the flexible solar cell 1, the frictional force and impact transmitted from the flexible solar cell 1 to the protrusion are reduced, so even if the flexible solar cell 1 is blown away, damage to the protrusion 2 can be reduced.

[0012] On the other hand, by using the easily deformable member 4, deformation of the flexible solar cell due to strong winds and damage to the mounting surface can be suppressed compared to when it is fixed with conventional strength without using the easily deformable member 4. However, because the structure is such that the position of the flexible solar cell 1 shifts when exposed to strong winds, the fixing force is inevitably reduced compared to when the flexible solar cell 1 is firmly fixed. Nevertheless, even if the flexible solar cell 1 is blown away by an unbearable strong wind, because the flexible solar cell 1 is light and flexible, the severity of the damage to the surrounding environment and human body is small, and as mentioned above, damage and scattering of the mounting surface (protrusion 2) are unlikely, so it is also highly safe from the viewpoint of the mounting surface. Rather, it is more dangerous when the flexible solar cell 1 is firmly fixed and damaged with little deformation, so overall safety can be enhanced by deliberately setting the fixing force to such an extent that it will be blown away when exposed to excessively strong winds. The easily deformable member 4 only needs to be placed at least between the protrusion 2 and the flexible solar cell 1, but from the viewpoint of appropriately distributing the force from the fixing member 3 and further suppressing damage to the flexible solar cell 1, it may also be placed between the flexible solar cell 1 and the fixing member 3 as shown in Figure 3. Furthermore, the easily deformable member 4 may be independent of the flexible solar cell 1 or may be integrated with it.

[0013] Furthermore, Figure 4 shows a schematic cross-sectional view illustrating an example of a flexible solar cell and an easily deformable member in the installation structure of the flexible solar cell of the present invention, and Figure 5 shows a top view of Figure 4. Figures 4 and 5 show the arrangement of the easily deformable member with respect to the flexible solar cell before installation. As shown in Figures 4 and 5, the flexible solar cell 1 has a structure in which a power generation section 11, a sealing layer 12 that seals the entire power generation section, a front sheet 13 on the outermost surface on the light-receiving surface side, and a back sheet 14 on the outermost surface on the installation surface side are laminated. In addition, the non-power generation section where no power generation section is formed becomes the fixed section with respect to the installation surface, and the easily deformable member 4 is arranged over the entire area in the fixing direction. Note that if the flexible solar cell 1 has only one power generation section 11, the non-power generation section at the edge of the flexible solar cell 1 becomes the fixed section.

[0014] Examples of installation surfaces having continuous protrusions in one direction include corrugated metal roofs and standing seam roofs. The installation surface may or may not have a slope, but it is preferable to have a slope. A sloped installation surface allows for the optimization of the arrangement of flexible solar cells, thereby increasing power generation efficiency.

[0015] The material of the mounting surface is not particularly limited and includes, for example, metals such as steel, aluminum alloy, stainless steel, nickel alloy, and copper alloy; hard plastics such as polyvinyl chloride, polycarbonate, acrylic, polypropylene, ABS resin, and AS resin; rubber; ceramics; or composite materials thereof.

[0016] The above-mentioned flexible solar cell can be a conventionally known flexible solar cell. Examples of the structure of the above-mentioned flexible solar cell include a structure in which a power generation unit sealed by a sealing layer is arranged between a back sheet and a front sheet.

[0017] The above-mentioned power generation unit is composed of a substrate, electrodes, counter electrodes, a photoelectric conversion layer, an electron transport layer, a hole transport layer, etc., and has at least electrodes, a photoelectric conversion layer, and counter electrodes. In this specification, "layer" means not only layers with clear boundaries, but also layers with a concentration gradient in which the contained elements gradually change. Elemental analysis of a layer can be performed, for example, by FE-TEM / EDS line analysis of a cross-section of the solar cell to confirm the elemental distribution of specific elements. Furthermore, in this specification, "layer" means not only flat, thin-film layers, but also layers that can form a complex, interwoven structure together with other layers.

[0018] Examples of the above-mentioned substrates include resin films made of polyimide or polyester-based heat-resistant polymers, metal foils, and thin glass sheets. Among these, PET resin films are preferred from the viewpoint of cost and heat resistance.

[0019] The materials for the electrodes and counter electrodes are not particularly limited and include, for example, FTO (fluorine-doped tin oxide), ITO (tin-doped indium oxide), AZO (aluminum zinc oxide), IZO (indium zinc oxide), GZO (gallium zinc oxide), sodium, sodium-potassium alloy, lithium, magnesium, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, Al / Al ２ O ３ Examples include mixtures, Al / LiF mixtures, etc. Also, gold, silver, titanium, molybdenum, tantalum, tungsten, carbon, nickel, chromium, etc. These materials may be used individually or in combination of two or more.

[0020] The thickness of the electrode and counter electrode is not particularly limited, but a preferred lower limit is 10 nm and a preferred upper limit is 1000 nm. If the thickness is 10 nm or more, the electrode can function while suppressing resistance. If the thickness is 1000 nm or less, the light transmittance can be further improved. A more preferred lower limit for the thickness of the electrode and counter electrode is 50 nm and a more preferred upper limit is 500 nm.

[0021] Examples of photoelectric conversion materials constituting the above-mentioned photoelectric conversion layer include organic-inorganic perovskite compounds and organic semiconductors. In particular, it is preferable that the above-mentioned photoelectric conversion layer contains an organic-inorganic perovskite compound because it has high photoelectric conversion efficiency and allows for the inexpensive manufacture of large-area flexible solar cells. An organic-inorganic perovskite compound is a compound represented by the general formula AMX (where A is an organic base compound and / or alkali metal, M is a lead or tin atom, and X is a halogen atom), and a solar cell containing such an organic-inorganic perovskite compound is also called an organic-inorganic hybrid solar cell.

[0022] The above A is an organic base compound and / or alkali metal. Specifically, the above organic base compounds include, for example, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, ethylmethylamine, methylpropylamine, butylmethylamine, methylpentylamine, hexylmethylamine, ethylpropylamine, ethylbutylamine, formamidine, acetamidine, guanidine, imidazole, azole, pyrrole, aziridine, azirine, azetidine, azeto, azole, imidazoline, carbazole and their ions (for example, methylammonium (CH4) ３ NH ３ Examples include ) and phenethylammonium. Among these, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, formamidine, acetamidine and their ions and phenethylammonium are preferred, and methylamine, ethylamine, propylamine, formamidine and their ions are more preferred. Examples of the alkali metals mentioned above include lithium, sodium, potassium, rubidium, cesium, etc.

[0023] The above M is a metal atom, which is either a lead or tin atom. These metal atoms may be used individually or in combination of two or more types.

[0024] The above X is a halogen atom, and examples of halogen atoms include chlorine, bromine, iodine, sulfur, and selenium. These halogen atoms may be used individually or in combination of two or more. By including a halogen in the structure, the above organic-inorganic perovskite compound becomes soluble in organic solvents, making it possible to apply it to inexpensive printing methods and the like. In particular, X is preferably iodine because it narrows the energy band gap of the above organic-inorganic perovskite compound.

[0025] The above organic-inorganic perovskite compound preferably has a cubic crystal structure in which a metal atom M is located at the body center, an organic base compound or alkali metal A is located at each vertex, and a halogen atom X is located at the face center. Although the details are not clear, it is presumed that having the above structure allows the orientation of the octahedra in the crystal lattice to change easily, thereby increasing the electron mobility in the organic-inorganic perovskite compound and improving the photoelectric conversion efficiency of the solar cell.

[0026] The above organic-inorganic perovskite compound is preferably a crystalline semiconductor. A crystalline semiconductor is a semiconductor in which the X-ray scattering intensity distribution can be measured and a scattering peak can be detected. The crystalline nature of the organic-inorganic perovskite compound increases the electron mobility within it, thereby improving the photoelectric conversion efficiency of the flexible solar cell.

[0027] Furthermore, the degree of crystallinity can also be evaluated as an indicator of crystallization. The degree of crystallinity can be determined by separating the scattering peaks originating from the crystalline portion and the halos originating from the amorphous portion, detected by X-ray scattering intensity distribution measurement, by fitting them together, calculating the integral of each intensity, and then calculating the ratio of the crystalline portion to the whole. The preferred lower limit for the degree of crystallinity of the above organic-inorganic perovskite compound is 30%. When the degree of crystallinity is 30% or higher, the electron mobility in the above organic-inorganic perovskite compound increases, improving the photoelectric conversion efficiency of the solar cell. A more preferred lower limit for the degree of crystallinity is 50%, and an even more preferred lower limit is 70%. In addition, methods for increasing the degree of crystallinity of the above organic-inorganic perovskite compound include, for example, thermal annealing, irradiation with high-intensity light such as lasers, and plasma irradiation.

[0028] The above photoelectric conversion layer may further contain an organic semiconductor or an inorganic semiconductor in addition to the above organic-inorganic perovskite compound, as long as the effects of the present invention are not impaired. Note that the organic semiconductor or inorganic semiconductor referred to herein may function as a hole transport layer or an electron transport layer. Examples of the above organic semiconductors include compounds having a thiophene skeleton such as poly(3-alkylthiophene). Other examples include conductive polymers having a polyparaphenylene vinylene skeleton, a polyvinylcarbazole skeleton, a polyaniline skeleton, a polyacetylene skeleton, and the like. Further examples include compounds having a porphyrin skeleton such as a phthalocyanine skeleton, a naphthalocyanine skeleton, a pentacene skeleton, a benzoporphyrin skeleton, a spirobifluorene skeleton, and the like, as well as carbon-containing materials such as optionally surface-modified carbon nanotubes, graphene, and fullerenes.

[0029] Examples of the above inorganic semiconductors include titanium oxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, zinc sulfide, CuSCN, Cu ２ O, CuI, MoO ３ , V ２ O ５ , WO ３ , MoS ２ , MoSe ２ , Cu ２ S, and the like.

[0030] When the photoelectric conversion layer contains the organic-inorganic perovskite compound and the organic semiconductor or the inorganic semiconductor, it may be a laminate obtained by laminating a thin-film organic semiconductor or inorganic semiconductor portion and a thin-film organic-inorganic perovskite compound portion, or may be a composite film obtained by compositing an organic semiconductor or inorganic semiconductor portion and an organic-inorganic perovskite compound portion. A laminate is preferable from the viewpoint of simple production process, and a composite film is preferable from the viewpoint that the charge separation efficiency in the organic semiconductor or the inorganic semiconductor can be improved.

[0031] The thickness of the thin film-like organic-inorganic perovskite compound portion described above has a preferred lower limit of 5 nm and a preferred upper limit of 5000 nm. If the thickness is 5 nm or more, sufficient light absorption becomes possible, and the photoelectric conversion efficiency increases. If the thickness is 5000 nm or less, the occurrence of regions where charge separation is not possible can be suppressed, leading to an improvement in photoelectric conversion efficiency. A more preferred lower limit for the thickness is 10 nm, a more preferred upper limit is 1000 nm, an even more preferred lower limit is 20 nm, and an even more preferred upper limit is 500 nm.

[0032] When the photoelectric conversion layer is a composite film formed by combining an organic semiconductor or inorganic semiconductor portion with an organic-inorganic perovskite compound portion, the preferred lower limit of the thickness of the composite film is 30 nm, and the preferred upper limit is 3000 nm. If the thickness is 30 nm or more, sufficient light can be absorbed, and the photoelectric conversion efficiency will be high. If the thickness is 3000 nm or less, the charge can reach the electrodes more easily, and the photoelectric conversion efficiency will be high. A more preferred lower limit of the thickness is 40 nm, a more preferred upper limit is 2000 nm, an even more preferred lower limit is 50 nm, and an even more preferred upper limit is 1000 nm.

[0033] The method for forming the above-mentioned photoelectric conversion layer is not particularly limited and includes methods such as vacuum deposition, sputtering, vapor deposition (CVD), electrochemical deposition, and printing. In particular, by employing the printing method, solar cells that can exhibit high photoelectric conversion efficiency can be easily formed over a large area. Examples of printing methods include spin coating and casting, and methods using the printing method include roll-to-roll.

[0034] The above-mentioned power generation unit may have an electron transport layer between the electrode acting as the cathode or the counter electrode and the photoelectric conversion layer. The material of the electron transport layer is not particularly limited and includes, for example, N-type conductive polymers, N-type low molecular weight organic semiconductors, N-type metal oxides, N-type metal sulfides, alkali metal halides, alkali metals, surfactants, etc. Specifically, examples include cyano group-containing polyphenylene vinylene, boron-containing polymers, vasocuproin, vasophenanthrene, hydroxyquinolinatoaluminum, oxadiazole compounds, benzimidazole compounds, naphthalenetetracarboxylic acid compounds, perylene derivatives, phosphine oxide compounds, phosphine sulfide compounds, fluoro group-containing phthalocyanines, titanium dioxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, zinc sulfide, etc.

[0035] The electron transport layer described above may consist only of a thin-film electron transport layer, but it is preferable to include a porous electron transport layer. In particular, when the photoelectric conversion layer is a composite film formed by combining an organic semiconductor or inorganic semiconductor portion with an organic-inorganic perovskite compound portion, a more complex composite film (a more intricately interwoven structure) can be obtained, and the photoelectric conversion efficiency is higher, so it is preferable that the composite film is fabricated on a porous electron transport layer.

[0036] The preferred lower limit for the thickness of the electron transport layer is 1 nm, and the preferred upper limit is 2000 nm. If the thickness is 1 nm or more, holes can be sufficiently blocked. If the thickness is 2000 nm or less, it will not be a resistance during electron transport, and the photoelectric conversion efficiency will be high. A more preferred lower limit for the thickness of the electron transport layer is 3 nm, a more preferred upper limit is 1000 nm, an even more preferred lower limit is 5 nm, and an even more preferred upper limit is 500 nm.

[0037] The power generation unit may comprise a hole transport layer between the electrode corresponding to the anode and cathode or the counter electrode and the photoelectric conversion layer. The material of the hole transport layer is not particularly limited, and the hole transport layer may be formed of an organic material. Examples of the material of the hole transport layer include P-type conductive polymers, P-type low-molecular organic semiconductors, P-type metal oxides, P-type metal sulfides, surfactants and the like, and specific examples thereof include compounds having a thiophene skeleton such as poly(3-alkylthiophene). Further, for example, conductive polymers having a triphenylamine skeleton, a polyparaphenylene vinylene skeleton, a polyvinyl carbazole skeleton, a polyaniline skeleton, a polyacetylene skeleton, etc. may also be mentioned. Further examples include compounds having a phthalocyanine skeleton, a naphthalocyanine skeleton, a pentacene skeleton, a porphyrin skeleton such as a benzoporphyrin skeleton, a spirobifluorene skeleton, etc., molybdenum sulfide, tungsten sulfide, copper sulfide, tin sulfide, etc., fluoro group-containing phosphonic acids, carbonyl group-containing phosphonic acids, copper compounds such as CuSCN, CuI, etc.

[0038] The encapsulating material that serves as the main component of the encapsulating layer only needs to be capable of encapsulating the power generation unit. Specific examples of the encapsulating material include thermosetting resins, thermoplastic resins, inorganic materials and the like. Examples of the thermosetting resin or thermoplastic resin include epoxy resins, acrylic resins, silicone resins, phenol resins, melamine resins, urea resins and the like. Further examples include butyl rubber, polyester, polyurethane, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, polyvinyl acetate, ABS resins, polybutadiene, polyamide, polycarbonate, polyimide, polyisobutylene, polyisoprene and the like. Among these, when the power generation unit contains an organic-inorganic perovskite compound in the photoelectric conversion layer, the durability of the power generation unit over time can be further improved, so polybutadiene, polyisobutylene, polyisoprene and butyl rubber, which are resins having at least one skeleton selected from the group consisting of polybutadiene, polyisobutylene and polyisoprene, are preferable.

[0039] From the perspective of balancing the protection performance and flexibility of the power generation unit, the thickness of the sealing layer is preferably 10 µm or more, more preferably 50 µm or more, preferably 1000 µm or less, and more preferably 700 µm or less. Here, the thickness of the sealing layer refers to the maximum thickness among the portions consisting only of the sealing layer.

[0040] The front sheet is disposed on the outermost surface of the upper side of the flexible solar cell, and has the role of suppressing light reflection and improving the drainage performance of the flexible solar cell surface by forming patterns such as irregularities and arcs on the surface. The material of the front sheet is not particularly limited as long as it has transparency, and examples thereof include fluorine-containing resins, vinyl chloride-based resins, polyethylene-based resins, and polycarbonate-based resins. Specific examples include polycarbonate, polyvinyl chloride, tetrafluoroethylene resin, polyvinylidene fluoride, and polychlorotrifluoroethylene. Among these, fluorine-containing resins are preferred because of their excellent weather resistance.

[0041] The thickness of the front sheet is not particularly limited, but from the perspective of balancing light transmittance and functionality of the front sheet, it is preferably 25 µm or more, more preferably 50 µm or more, preferably 1000 µm or less, and more preferably 300 µm or less.

[0042] The back sheet has the role of preventing intrusion of substances that cannot be completely prevented from intrusion by only the sealing layer, thereby improving the weather resistance of the flexible solar cell. In particular, for perovskite solar cells, due to compatibility issues with the power generation unit, the options for the sealing layer in contact with the power generation unit are limited, and it is not possible to use commonly used resin materials with excellent water vapor transmittance. In addition, moisture is likely to accumulate on the installation surface side of the photovoltaic power generation device, which is more prone to degradation caused by moisture. Therefore, when an organic-inorganic perovskite compound is used for the power generation unit, it is preferable that the back sheet is made of a material with low water vapor transmittance. Examples of the material for the back sheet include polyethylene terephthalate.

[0043] The thickness of the backsheet is not particularly limited, but from the viewpoint of balancing flexibility and the functionality of the backsheet, it is preferably 50 μm or more, more preferably 100 μm or more, preferably 1000 μm or less, and most preferably 500 μm or less.

[0044] The shape of the flexible solar cell described above is not particularly limited to a sheet shape, and examples include circular, elliptical, polygonal, etc., which can be appropriately determined according to the installation surface.

[0045] The flexible solar cell described above preferably has a bending strength of 10 MPa or more, more preferably 20 MPa or more, and even more preferably 50 MPa or more. Having the lower limit of the bending strength of the flexible solar cell within this range further improves its handling. Furthermore, the flexible solar cell preferably has a bending strength of 200 MPa or less, more preferably 150 MPa or less, and even more preferably 100 MPa or less. Having the upper limit of the bending strength of the flexible solar cell within this range further improves its flexibility. The bending strength of the flexible solar cell can be measured by a method compliant with JIS K 7171.

[0046] The flexible solar cell described above preferably has a flexural modulus of 100 MPa or more, and more preferably 500 MPa or more. Having the lower limit of the flexural modulus of the flexible solar cell within this range further improves its handling. Furthermore, the flexible solar cell preferably has a flexural modulus of 10,000 MPa or less, and more preferably 5,000 MPa or less. Having the upper limit of the flexural modulus of the flexible solar cell within this range further improves its flexibility. The flexural modulus of the flexible solar cell can be measured by a method compliant with JIS K 7171.

[0047] The structure of the fixing member described above is not particularly limited as long as it can be fixed to the protrusion while sandwiching the flexible solar cell. Examples include a pipe-shaped structure with a C-shaped cross-section, or a structure consisting of a part that clamps one side of the protrusion and a part that clamps the other side, with these parts connected by screws, hinges, etc.

[0048] The material of the fixing member described above only needs to have sufficient rigidity to fix the flexible solar cell. Examples include metals such as steel, aluminum alloy, stainless steel, nickel alloy, and copper alloy; hard plastics such as polyvinyl chloride, polycarbonate, acrylic, polypropylene, ABS resin, AS resin, and PPS resin; rubber; ceramics; or composite materials thereof. In particular, it is preferable to use a flame-retardant material so as to suppress the spread of fire to the installation surface in the event of a fire occurring in the flexible solar cell. Here, a flame-retardant material means a material that has a flame retardancy of V-0 or higher in the UL94 vertical combustion test.

[0049] The length of the fixing member is not particularly limited as long as it is equal to or greater than the length of the side of the flexible solar cell that is clamped. In particular, from the viewpoint of making installation easier by allowing for some leeway in positioning and from the viewpoint of miniaturizing by keeping the length down, the length of the fixing member is preferably 1 cm or more, more preferably 5 cm or more, preferably 15 cm or less, and most preferably 10 cm or less than the length of the side of the flexible solar cell that is clamped.

[0050] The above-mentioned easily deformable member has a compressive strength of 0.5 MPa or more and 400 MPa or less. A compressive strength of 0.5 MPa or more allows the flexible solar cell to be firmly fixed under normal conditions, while a compressive strength of 400 MPa or less allows it to deform in the planar direction when strong winds blow, thus preventing damage to the flexible solar cell. The compressive strength of the above-mentioned easily deformable member is preferably 1 MPa or more, more preferably 2 MPa or more, even more preferably 5 MPa or more, even more preferably 5.5 MPa or more, very preferably 10 MPa or more, even more preferably 25 MPa or more, especially preferably 50 MPa or more, and particularly preferably 150 MPa or more. Furthermore, the compressive strength of the above-mentioned easily deformable member is preferably 380 MPa or less, more preferably 350 MPa or less, even more preferably 300 MPa or less, and even more preferably 250 MPa or less. The compressive strength of the above-mentioned easily deformable member can be measured according to the following JIS standard measurement method depending on the type of material. JIS K 7171: Compression testing method for plastics JIS K 6254: Compression testing method for rubber JIS Z 2241: Compression testing method for metallic materials JIS R 1608: Compression testing method for fine ceramics JIS K 7076: Compression testing method for fiber-reinforced plastics JIS A 1108: Compression strength testing method for concrete

[0051] The thickness of the easily deformable member described above is not particularly limited, but from the viewpoint of balancing the fixing force of the flexible solar cell with the amount of deformation of the easily deformable member, it is preferably 300 μm or more, more preferably 450 μm or more, even more preferably 500 μm or more, preferably 5000 μm or less, more preferably 1000 μm or less, and even more preferably 700 μm or less.

[0052] The material of the easily deformable member described above is not particularly limited as long as it can be deformed in the planar direction when a strong force is applied. Examples include resin materials such as silicone resin, fibrous materials such as glass wool and steel wool, glass fiber composite tent fabric and composite materials thereof. In particular, the easily deformable member is preferably made of a flame-retardant material so as to suppress the spread of fire to the installation surface in the event that the flexible solar cell catches fire, and is more preferably made of a fibrous flame-retardant material because it has excellent long-term durability. Examples of the fibrous flame-retardant material described above include glass wool and tent fabric.

[0053] (Embodiment 2) Figure 6 shows a schematic cross-sectional view illustrating another example of a flexible solar cell and a deformable member in the installation structure of the flexible solar cell of the present invention. In the flexible solar cell installation structure of Embodiment 2, a plurality of flexible solar cells 1, each consisting of a power generation unit 11, a sealing layer 12, a front sheet 13, and a back sheet 14, are arranged at regular intervals on a sheet-like member 5. The space between the flexible solar cells 1 on the sheet-like member 5 is a portion that is fixed to a protrusion on the installation surface, and a deformable member 4 is arranged therein. By arranging the flexible solar cells 1 on the sheet-like member 5, handling and ease of installation are improved compared to the case where the flexible solar cells 1 are installed individually, and the design can be easily adapted to the area and shape of the installation surface.

[0054] The above-mentioned sheet-like member is not particularly limited as long as it is flexible, and examples include resin sheets, fiber-reinforced sheets, metal sheets, or composite materials thereof. In particular, it is preferable that the above-mentioned sheet-like member be made of a flame-retardant material, as this makes it difficult for the fire to spread to the installation surface even if the flexible solar cell catches fire.

[0055] The thickness of the sheet-like member described above is not particularly limited, but from the viewpoint of ensuring strength, it is preferably 300 μm or more, more preferably 450 μm or more, and even more preferably 500 μm or more. Furthermore, from the viewpoint of ensuring flexibility, it is preferably 5000 μm or less, more preferably 3000 μm or less, and even more preferably 1000 μm or less.

[0056] (Embodiment 3) Figure 7 shows a schematic cross-sectional view illustrating another example of a flexible solar cell and a deformable member in the installation structure of the flexible solar cell of the present invention. In the installation structure of the flexible solar cell of Embodiment 3, the backsheet 14 plays the role of the sheet-like member 5 of Embodiment 2, and a flexible solar cell 1 sharing the backsheet 14 is formed by stacking a plurality of power generation units 11, sealing layers 12, and front sheets 13 on one backsheet 14. Also, similar to Embodiment 2, the space between the stacked bodies consisting of the power generation unit 11, sealing layer 12, and front sheet 13 is the part that is fixed to the protrusions on the installation surface, and the deformable member 4 is located there. Furthermore, in Embodiment 3, a frame member 6 is arranged in contact with the sealing layer 12 and surrounding at least the entire side surface of the sealing layer 12. By providing such a frame member 6, the surrounding part of the power generation unit 11 can be reinforced, and the intrusion of moisture from the side surface of the sealing layer 12 can be suppressed, thereby further improving durability. The frame member 6 may have its ends overlap with the light-receiving surface of the front sheet 13, and a portion of it may overlap with the power generation unit 11, but it is preferable that it does not overlap with the portion that is fixed to the mounting surface.

[0057] The material of the frame member described above is not particularly limited as long as it has a certain degree of strength and excellent water vapor barrier performance, for example, aluminum, stainless steel, etc. Among these, aluminum is preferred because it is lightweight.

[0058] The thickness of the frame member described above is not particularly limited, but from the viewpoint of balancing reinforcing performance, water vapor barrier performance and flexibility, it is preferably 30 μm or more, more preferably 500 μm or more, preferably 5000 μm or less, and even more preferably 3000 μm or less.

[0059] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0060] (Example 1) A glass fiber composite tent fabric (glass fiber / polyvinyl chloride resin composite material, Hit 100FM, manufactured by Izumi Co., Ltd.) with a thickness of 0.52 mm was bonded to a flexible solar cell using an organic-inorganic perovskite compound as a photoelectric conversion layer, in the arrangement shown in Figures 4 and 5. Next, the flexible solar cell was placed so that the center of the easily deformable member aligned with the seam (protrusion) of the corrugated metal roof, which was the installation surface. Then, while pulling the flexible solar cell, the easily deformable member was sandwiched between pipe-shaped fixing members with a C-shaped cross-section made of aluminum, thereby fixing the flexible solar cell to the cross-sectional shape shown in Figure 3. The compressive strength of the easily deformable member measured using the above method was 250 MPa.

[0061] (Examples 2-7, Comparative Example 2) Flexible solar cells were fixed to a corrugated metal roof in the same manner as in Example 1, except that the material and thickness of the easily deformable member were as shown in Table 1.

[0062] (Comparative Example 1) A flexible solar cell was fixed to a corrugated metal roof in the same manner as in Example 1, except that a deformable member was not used.

[0063] <Evaluation> The photovoltaic power generation systems obtained in the examples and comparative examples were evaluated as follows. The results are shown in Table 1.

[0064] (1) Evaluation of fixation A wind of 12 m / s was applied to the side of the installed solar power generation sheet (a cross-sectional direction perpendicular to the extension direction of the protrusion) for 5 minutes. Fixation was evaluated by marking "○" if the flexible solar cell did not detach after the wind was applied, and "×" if it detached.

[0065] (2) Evaluation of detachability A wind of 46 m / s was applied to the side of the installed solar power generation sheet for 5 minutes (a cross-sectional direction perpendicular to the extension direction of the protrusions). After the wind was applied, the stability was evaluated as follows: if the flexible solar cell shifted and deformed but was not damaged, it was marked as "○"; if the flexible solar cell detached but was not damaged, it was marked as "△"; and if the flexible solar cell was damaged, it was marked as "×".

[0066]

[0067] According to the present invention, it is possible to provide a flexible solar cell installation structure that offers high safety even when exposed to strong winds.

[0068] 1 Flexible solar cell 11 Power generation section 12 Sealing layer 13 Front sheet 14 Back sheet 2 Protrusion 3 Fixing member 4 Easily deformable member 5 Sheet-like member 6 Frame member

Claims

1. An installation structure for a flexible solar cell comprising: an installation surface having a continuous protrusion in one direction; a flexible solar cell disposed on the surface of the installation surface having the protrusion; a fixing member for sandwiching and fixing the flexible solar cell on the protrusion; and a deformable member disposed between the protrusion and the flexible solar cell, wherein the deformable member is sandwiched together with the flexible solar cell between the fixing member and the protrusion, and the compressive strength of the deformable member is 0.5 MPa or more and 400 MPa or less.

2. The installation structure for a flexible solar cell according to claim 1, characterized in that the easily deformable member is provided between the flexible solar cell and the fixing member at the portion sandwiched by the fixing member.

3. The installation structure for a flexible solar cell according to claim 1 or 2, wherein the easily deformable member is made of a flame-retardant material.

4. The installation structure for a flexible solar cell according to claim 3, wherein the flame-retardant material is a fibrous flame-retardant material.

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