Solar Cell Module

Abstract

This solar cell module is characterized by including: a transparent substrate provided with a first side surface, a second side surface, and a main surface; a power generation layer provided on the main surface of the transparent substrate; a sealing part provided so as to cover at least the first side surface, the second side surface, and a side surface of the power generation layer, wherein the transparent substrate is provided in plurality, and the plurality of transparent substrates are arranged so that the first side surface and the second side surface face each other.　

Description

[Technical field]

[0001] The present invention relates to a solar cell module. [Background technology]

[0002] As interest in renewable energy grows, solar cells such as crystalline silicon solar cells and dye-sensitized solar cells are becoming more widespread. These solar cells can generate large amounts of power by increasing the power generation area. A structure has been proposed in which multiple power generation layers are arranged on the surface of a single glass substrate, and these power generation layers generate power using light transmitted through the glass substrate (Patent Document 1).

[0003] However, in this structure, gaps are formed between adjacent power generation layers, and some of the light irradiated to the glass substrate passes through the gap and is not irradiated to the power generation layers, resulting in reduced power generation efficiency. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 022817 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above problems, and has an object to improve power generation efficiency. [Means for solving the problem]

[0006] The solar cell module of the present invention comprises a transparent substrate having a first side, a second side, and a main surface, a power generation layer provided on the main surface of the transparent substrate, and a sealing portion provided so as to cover at least the first side, the second side, and the side of the power generation layer, wherein a plurality of the transparent substrates are provided and the plurality of transparent substrates are arranged so that the first side and the second side face each other.

[0007] In the solar cell module, a light reflecting portion having a refractive index different from that of the transparent substrate may be provided between the first side surface and the second side surface.

[0008] In the solar cell module, the light reflecting portion may include a resin.

[0009] In the solar cell module described above, the resin may be any one of acrylic resin, polycarbonate, epoxy resin, silicone resin, fluororesin, and engineering plastic.

[0010] In the solar cell module, a silane coupling layer may be provided on the first side surface, and the light reflecting portion may be provided on the silane coupling layer.

[0011] In the solar cell module, the light reflecting portion may include a light reflecting filler.

[0012] In the solar cell module, a reflective layer may be provided on the first side surface.

[0013] In the solar cell module, the reflective layer may be a metal oxide layer.

[0014] In the solar cell module, the sealing portion may include a resin.

[0015] In the solar cell module, the power generation layer may be a layer of a plurality of semiconductor particles having a dye adsorbed on the surface. Effect of the Invention

[0016] According to the present invention, power generation efficiency can be improved. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view of a solar cell used in the study. [Diagram 2] FIG. 2 is a cross-sectional view of a solar cell module capable of obtaining a higher voltage than the example of FIG. [Diagram 3] 13(a) and 13(b) are cross-sectional views for explaining the problem. [Figure 4] 1(a) and 1(b) are perspective views (part 1) of a solar cell according to a first embodiment during its manufacture. [Diagram 5] 13(a) and 13(b) are perspective views (part 2) of the solar cell according to the first embodiment during its manufacture. [Figure 6] 13(a) and 13(b) are perspective views (part 3) of the solar cell according to the first embodiment during its manufacture. [Figure 7] 13(a) and 13(b) are perspective views (part 4) of the solar cell according to the first embodiment during its manufacture. [Figure 8] 2 is an enlarged cross-sectional view of an edge portion of the solar cell according to the first embodiment. FIG. [Figure 9] FIG. 1 is a plan view of a solar cell module according to a first embodiment. [Figure 10] 1 is a cross-sectional view of a solar cell module according to a first embodiment. [Figure 11] 1(a), 1(b), and 1(c) are plan views showing examples of arrangements of solar cells according to the first embodiment. [Figure 12] 1 is an enlarged cross-sectional view of a solar cell module according to a first embodiment. [Figure 13] FIG. 6 is an enlarged cross-sectional view of a solar cell module according to a second embodiment. [Figure 14] FIG. 11 is an enlarged cross-sectional view of a solar cell module according to a fourth embodiment. [Figure 15] FIG. 11 is an enlarged cross-sectional view of a solar cell module according to another embodiment. [Figure 16] FIG. 11 is an enlarged cross-sectional view of a solar cell module according to still another example of another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Prior to describing the present embodiment, the matters considered by the inventors of the present application will be described. Fig. 1 is a cross-sectional view of the solar cell used in the study. This solar cell 1 is a dye-sensitized solar cell, and is composed of a transparent substrate 2 on which a transparent electrode layer 3, a reverse electron transfer prevention layer 4, a power generation layer 5, a solid electrolyte layer 6, and a counter electrode layer 7 are formed in this order.

[0019] Among these, the transparent substrate 2 is a glass substrate, on which an ITO (Indium Tin Oxide) layer is formed as a transparent electrode layer 3. The reverse electron transfer prevention layer 4 is, for example, a titanium oxide layer made from a titanium alkoxide precursor. The power generation layer 5 is a layer in which a dye is adsorbed onto a plurality of titanium oxide particles. An example of the dye is CYC-B11.

[0020] The solid electrolyte layer 6 is a layer containing, for example, iodine and 1,3-dimethylimidazolium iodide (DMII), and a platinum layer, for example, is provided thereon as a counter electrode layer 7. Furthermore, a resin sealing portion 8 is provided on the side surface of the solar cell 1 to prevent the power generation layer 5 and the solid electrolyte layer 6 from being exposed to the air.

[0021] In such a solar cell 1, the region where the transparent electrode layer 3, the reverse electron transfer prevention layer 4, the power generation layer 5, the solid electrolyte layer 6, and the counter electrode layer 7 overlap each other becomes the cell region Rc that generates electricity using light transmitted through the transparent substrate 2.

[0022] However, since there is only one cell region Rc in this solar cell 1, a high voltage cannot be obtained. Although it depends on the type of dye-sensitized solar cell, in this example, the generated voltage of the solar cell 1 is only about 0.5V.

[0023] Fig. 2 is a cross-sectional view of a solar cell module 11 capable of obtaining a higher voltage than the example of Fig. 1. In Fig. 2, the same elements as those explained in Fig. 1 are given the same reference numerals, and their explanation will be omitted below.

[0024] 2, in this solar cell module 11, a plurality of cell regions Rc are formed by separating each of the layers 3 to 7 on the transparent substrate 2 into a plurality of parts. In addition, sealing portions 8 are provided between each of the cell regions Rc, and the sealing portions 8 prevent the power generation layers 5 of the cell regions Rc from being connected to each other.

[0025] According to this, by connecting the batteries in the cell region Rc in series with each other by wiring (not shown), it is possible to obtain a higher voltage than in FIG.

[0026] However, through investigations by the present inventors, it has become clear that this solar cell module 11 has the following problems.

[0027] 3(a) and (b) are cross-sectional views for explaining this problem. As shown in Fig. 3(a), in the solar cell module 11, the power generation layer 5 is separated into multiple parts, so that the light L passes through the gaps between these power generation layers 5. As a result, the light L cannot be fully utilized, and the power generation efficiency of the solar cell module 11 decreases.

[0028] Furthermore, as shown in FIG. 3(b), in this example, the transparent substrate 2 is provided large enough to cover each of the power generation layers 5, so that cracks 2x may occur in the transparent substrate 2 during the manufacture of the solar cell module 11. EXAMPLES

[0029] (First embodiment) In this embodiment, a dye-sensitized solar cell is manufactured as the solar cell as follows: Figures 4(a) to 7(b) are perspective views of the solar cell according to this embodiment during its manufacture.

[0030] First, as shown in FIG. 4(a), a transparent substrate 20 having a first main surface 20a and a second main surface 20b facing each other is prepared. Of these surfaces, the first main surface 20a is an incident surface into which light is incident during actual use. On the other hand, an ITO layer is formed in advance on the second main surface 20b as a transparent electrode layer 21 to a thickness of about 0.1 μm to 0.5 μm. Note that instead of the ITO layer, any of an FTO (fluorine doped tin oxide) layer, a zinc oxide layer, a laminated film of an indium-tin composite oxide layer and a silver layer, and an antimony-doped tin oxide layer may be formed as the transparent electrode layer 21.

[0031] The transparent substrate 20 is a glass substrate having a substantially square shape in a plan view, with the lengths Ax and Ay of each side being 5 mm to 40 mm, for example 15 mm. The thickness Az of the transparent substrate 20 is 0.1 mm to 3 mm, for example 1.1 mm. Instead of a glass substrate, a transparent plastic plate may be used as the transparent substrate 20.

[0032] 4(b), an alcohol solution prepared from titanium alkoxide is applied onto the transparent electrode layer 21 in the cell region Rc, and the alcohol solution is then heated and dried to form a reverse electron transfer prevention layer 22 with a thickness of about 5 nm to 0.1 μm. The drying temperature in this step is not particularly limited, and may be 450°C to 650°C, for example, about 550°C.

[0033] In this embodiment, a right-angled triangular region at a corner 20h of the rectangular transparent substrate 20 is defined as a first electrode region R1, and a pentagonal region excluding the corner 20h is defined as a cell region Rc.

[0034] Of the sides of the first electrode region R1 in the shape of a right triangle, the length Cx of one side sandwiching the right angle is 0.5 mm to 5 mm, for example 3 mm, and the length Cy of the other side is 0.5 mm to 5 mm, for example 3 mm. As a result, the area of ​​the cell region Rc excluding the first electrode region R1 on the second main surface 20b of the transparent substrate 20 is approximately 2.21 cm 2 It becomes.

[0035] The reverse electron transfer prevention layer 22 is formed only in the cell region Rc, and the transparent electrode layer 21 is exposed in the first electrode region R1.

[0036] Next, as shown in Fig. 5(a), a titanium paste containing titanium oxide particles with a particle size of 5 nm to 50 nm, for example 40 nm, is applied to the reverse electron transfer prevention layer 22 by screen printing to a thickness of about 1 µm to 10 µm, for example 5 µm, and then heated to remove organic components to form the power generation layer 25. The slurry is heated to a temperature of 450°C to 650°C, for example 550°C, and the drying time is 10 minutes to 120 minutes, for example about 30 minutes. The slurry is not particularly limited, but in this example, PST-30NRD, a titanium oxide paste manufactured by JGC Catalysts and Chemicals, is used as the slurry.

[0037] The semiconductor particles constituting the power generation layer 25 are not limited to titanium oxide particles, and the power generation layer 25 may be made of particles of any of the oxides of Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, Si, Cr, and Nb. 3 and CaTiO 3 Alternatively, the power generation layer 25 may be made of particles of a perovskite type oxide such as those mentioned above.

[0038] The power generation layer 25 is formed only in the cell region Rc, and is not formed in the first electrode region R1, so that the transparent electrode layer 21 in the first electrode region R1 is exposed. In this case, the area on which the titanium paste is printed is 2.21 cm 2 It becomes.

[0039] Thereafter, the transparent substrate 20 is immersed in an organic solution containing the dye, and the dye is adsorbed onto the surface of the semiconductor particles that constitute the power generation layer 25. The organic solution used is an organic solvent in which acetonitrile and t-butanol are mixed in a volume ratio of 1:1 and CYC-B11(K) is added as the dye. The concentration of the dye in the organic solution is 0.1 mM to 1 mM, for example, 0.2 mM. The organic solution is kept at a temperature of 0°C to 80°C, for example, 50°C, and the transparent substrate 20 is left standing in the organic solution for 1 hour to 12 hours, for example, 4 hours, to allow the dye to be adsorbed onto the power generation layer 25.

[0040] Furthermore, the dye is not limited to the above, and a metal complex dye or an organic dye may be adsorbed on the power generation layer 25. Among these, examples of the metal complex dye include transition metal complexes such as ruthenium-cis-diaqua-bipyridyl complex, ruthenium-tris complex, ruthenium-bis complex, osmium-tris complex, and osmium-bis complex. Zinc-tetra(4-carboxyphenyl)porphyrin and iron-hexacyanide complex are also examples of the metal complex dye.

[0041] Examples of organic dyes include 9-phenylxanthene dyes, coumarin dyes, acridine dyes, triphenylmethane dyes, tetraphenylmethane dyes, quinone dyes, azo dyes, indigo dyes, cyanine dyes, merocyanine dyes, xanthene dyes, and carbazole compound dyes.

[0042] Next, the process shown in FIG. 5(b) will be described. First, iodine, 1,3-dimethylimidazolium iodide (DMII), acetonitrile, and polyethylene oxide having a molecular weight of 1 million are mixed uniformly as the solid electrolyte precursor 26. Next, 0.1 μL to 50 μL, for example, 20 μL, of this solid electrolyte precursor 26 is dropped onto the power generation layer 25, and the power generation layer 25 is impregnated with the solid electrolyte precursor 26. Then, the power generation layer 25 is heated to 50° C. to 150° C., for example, 100° C., and this state is maintained for 1 minute to 60 minutes, for example, 5 minutes, thereby volatilizing the excess acetonitrile contained in the solid electrolyte precursor 26, and the solid electrolyte precursor 26 on the power generation layer 25 becomes the solid electrolyte layer 27. Then, the power generation layer 25 is returned to room temperature.

[0043] The electrolyte contained in the solid electrolyte precursor 26 is not limited to DMII. For example, iodine salts such as pyridinium salts, imidazolium salts, and triazolium salts, which are in a solid state near room temperature, or room-temperature molten salts in a molten state, may be used as the ionic liquid. Examples of such room-temperature molten salts include quaternary ammonium iodide compounds such as 1-methyl-3-propylimidazolium iodide, 1-butyl-3-methylimidazolium iodide (BMII), and 1-ethyl-pyridinium iodide.

[0044] Furthermore, the material of the solid electrolyte layer 27 is not limited to the above, and organic semiconductor materials such as molten salts containing redox pairs, oxadiazole compounds, and pyrazoline compounds may be used as the material of the solid electrolyte layer 27. The solid electrolyte layer 27 may also be formed of a metal halide material such as copper iodide or copper bromide.

[0045] 6(a), the counter electrode layer 33 is disposed above the solid electrolyte layer 27. The outer shape of the counter electrode layer 33 is made into a pentagon, the same as the cell region Rc, by cutting off one corner of a square with a side length of about 15 mm.

[0046] The counter electrode layer 33 is formed by forming a catalyst layer 32 with a thickness of about 0.01 μm to 0.1 μm, for example 0.05 μm, on a metal foil 31 with a thickness of 5 μm to 200 μm, for example 100 μm. The metal foil 31 is, for example, a titanium foil, and the catalyst layer 32 is, for example, a platinum layer.

[0047] In addition to the above-mentioned platinum, the material of the catalyst layer 32 may be metals having catalytic functions such as palladium, rhodium, and indium. The catalyst layer 32 may also be made of graphite. Furthermore, the catalyst layer 32 may also be made of carbon carrying platinum, indium-tin composite oxide, tin oxide doped with antimony, and tin oxide doped with fluorine. Other materials include organic semiconductors such as poly(3,4-ethylenedioxythiophene) (PEDOT) and polythiophene.

[0048] 6(b), the counter electrode layer 33 is adhered to the solid electrolyte layer 27 while removing air bubbles from between the solid electrolyte layer 27 and the counter electrode layer 33. By performing this step in a reduced pressure atmosphere or in vacuum, air bubbles are less likely to remain between the solid electrolyte layer 27 and the counter electrode layer 33.

[0049] In addition, in the cell region Rc, the transparent electrode layer 21, the power generation layer 25, the solid electrolyte layer 27, and the counter electrode layer 33 overlap each other in a planar view, and an electromotive force is generated in the power generation layer 25 in the cell region Rc when light is incident.

[0050] 7(a), a liquid in which a silane coupling material is diluted with alcohol is applied onto each side surface of the transparent substrate 20 and onto each of the opposing electrode layers 33 except for the second electrode region R2, and then dried to form a silane coupling layer with a thickness of 0.1 μm to 10 μm as the adhesion layer 40. As the silane coupling material, for example, KR-516 manufactured by Shin-Etsu Chemical Co., Ltd. is used.

[0051] The adhesive layer 40 is not formed on the counter electrode layer 33 in the second electrode region R2, and the counter electrode layer 33 is exposed in the second electrode region R2.

[0052] 7(b), an ultraviolet curable resin is applied onto the adhesive layer 40 and cured by ultraviolet light to form a sealing portion 41 having a thickness of about 10 μm to 500 μm. ThreeBond 3035B manufactured by ThreeBond Co., Ltd. is used as the ultraviolet curable resin.

[0053] If the ultraviolet curing resin is left as is after it has been applied, the ultraviolet curing resin will soak into the solid electrolyte layer 27, and the surface of the power generation layer 25 will be covered with the ultraviolet curing resin. To prevent this, it is preferable to cure the ultraviolet curing resin within about 10 minutes after it is applied.

[0054] Through the above steps, the basic structure of the solar cell 50 according to this embodiment is completed. Fig. 8 is an enlarged cross-sectional view of an edge of the solar cell 50. As shown in Fig. 8, the above-mentioned adhesion layer 40 is formed on the side surface 20s of the transparent substrate 20, and the sealing portion 41 is formed on the adhesion layer 40. The adhesion layer 40 increases the adhesion between the transparent substrate 20 and the sealing portion 41, and can prevent the sealing portion 41 from peeling off from the side surface 20s. The sealing portion 41 is provided so as to cover at least the side surface 20a of the transparent substrate 20 and the side surface of the power generation layer 25.

[0055] In addition, an adhesion layer 40 is also formed on the side and back surface of the counter electrode layer 33, and a sealing portion 41 is also formed on the adhesion layer 40. The adhesion layer 40 increases the adhesion between the counter electrode layer 33 and the sealing portion 41, and prevents the sealing portion 41 from peeling off from the counter electrode layer 33. Note that if the adhesion between the side surface 20s and the sealing portion 41 or the adhesion between the counter electrode layer 33 and the sealing portion 41 does not matter, the adhesion layer 40 may be omitted.

[0056] Next, a solar cell module using this solar cell 50 will be described. 9 is a plan view of the solar cell module according to this embodiment. As shown in FIG. 9, in this embodiment, eight solar cells 50 are arranged as a solar cell module 52 on a wiring board 51 with the transparent substrate 20 facing up. In addition, a silver paste (not shown) is provided between each solar cell 50 and the wiring board 51, and the electrode regions R1 and R2 of the solar cell 50 are electrically connected to the wiring board 51 by hardening the silver paste by heating. The silver paste is not particularly limited, but for example, DD-1630L-885 manufactured by Kyoto Elex Co., Ltd. can be used as the silver paste.

[0057] In this example, each solar cell 50 is connected in series with wiring on wiring board 51, so that a voltage eight times the voltage of one solar cell 50 is output from solar cell module 52.

[0058] The wiring board 51 is provided with a secondary battery 53, a wireless circuit 54, and a sensor 55. Of these, the secondary battery 53 is, for example, a lithium ion battery or a lithium ion capacitor, and is charged with power generated by the solar cell module 52. The wireless circuit 54 and the sensor 55 are driven by power from the secondary battery 53. For example, the sensor 55 is a temperature sensor or a humidity sensor, and transmits sensor information including the measured temperature and humidity to the wireless circuit 54. The wireless circuit 54 is a circuit that wirelessly transmits the sensor information by, for example, BLE (Bluetooth (registered trademark) Low Energy).

[0059] Fig. 10 is a cross-sectional view of a solar cell module 52. As shown in Fig. 10, in this embodiment, a transparent substrate 20 is provided for each solar cell 50, and a single transparent substrate is not used in common for a plurality of solar cells 50. Therefore, the transparent substrate 20 is less likely to crack, and the durability of the solar cell module 52 is improved.

[0060] There is no particular limitation on the arrangement of the solar cells 50. Figures 11(a) to 11(c) are plan views showing examples of the arrangement of the solar cells 50.

[0061] 11(a) to 11(c), each of the solar cells 50 can be arranged in any shape sharing one side in a plan view on the wiring board 51. In a conventional solar cell module, the shape of the wiring board 51 needs to be determined in accordance with the shape of the cell, whereas in this embodiment, the shape of the cell can be determined in accordance with the shape of the wiring board 51, improving the degree of freedom in arranging the solar cells 50.

[0062] Fig. 12 is an enlarged cross-sectional view of a solar cell module 52 according to this embodiment. As shown in Fig. 12, in this embodiment, the solar cells 50 are arranged so that the side surfaces 20s of adjacent transparent substrates 20 face each other.

[0063] When light L is obliquely incident on the side surface 20s of the transparent substrate 20, reflection, refraction, and scattering of the light L occur due to the difference in refractive index between the transparent substrate 20 and the sealing portion 41. For example, when the light L is reflected on the side surface 20s of the transparent substrate 20, the light L enters the power generation layer 25, increasing the amount of light entering the power generation layer 25, and improving the power generation efficiency of the solar cell module 52.

[0064] Furthermore, when light L is refracted at the side surface 20s of the transparent substrate 20, the refracted light L is incident on the power generation layer 25 of the adjacent solar cell 50, which also increases the amount of light incident on the power generation layer 25 and improves the power generation efficiency in the solar cell module 52. Furthermore, when light L is scattered at the side surface 20s of the transparent substrate 20, the scattered light L is incident on each of the power generation layers 25 of the two adjacent solar cells 50, which increases the amount of light incident on each power generation layer 25 and improves the power generation efficiency in the solar cell module 52.

[0065] Furthermore, when the sealing portion 41 is transparent, light refracted or scattered at the side surface 20s of the transparent substrate 20 passes through the sealing portion 41, increasing the amount of light incident on the power generation layer 25 of the adjacent solar cell 50, thereby improving the power generation efficiency of the solar cell module 52.

[0066] In particular, the power generation layer 25 of the dye-sensitized solar cell has a thickness of about 1 μm to 10 μm, which is thicker than the thickness (100 nm) of the silicon layer of a silicon solar cell. Therefore, the volume of the power generation layer 25 is large, and the power generation layer 25 is easily affected by the reflection, refraction, and scattering of the light L. In particular, the area of ​​the side surface 25s of the power generation layer 25 is larger than that of a silicon solar cell, and the light reflected from the side surface 20s is incident on the wide side surface 25s, further improving the power generation efficiency of the power generation layer 25.

[0067] In addition, although the distance t between the adjacent side surfaces 20s is not particularly limited, in this embodiment, the distance t between the side surfaces 20s is set to 2 mm or less. This makes it possible to prevent the area of ​​the power generation layer 25 per solar cell module 52 from becoming smaller, and prevents the power generation efficiency of the solar cell module 52 from decreasing.

[0068] Second embodiment Fig. 13 is an enlarged cross-sectional view of a solar cell module 52 according to this embodiment. In Fig. 13, the same elements as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and their description will be omitted below.

[0069] 13, in this embodiment, the gap between adjacent solar cells 50 is filled with silicone resin as a light reflecting portion 61. An example of the silicone resin is Silicone Sealant (Clear) manufactured by Cainz Co., Ltd. The refractive index of this silicone resin is 1.41.

[0070] Since the refractive index of the glass and sealing resin 41, which are materials of the transparent substrate 20, is about 1.5, in this embodiment, a light reflecting portion 61, which has a refractive index different from that of the transparent substrate 20 and the sealing resin 41, is provided between each solar cell 50. Due to such a difference in refractive index between the transparent substrate 20 and the light reflecting portion 61, in this embodiment, the reflectance of light L at the side surface 20s is increased. As a result, more light reflected at the side surface 20s of the transparent substrate 20 is incident on the power generation layer 25, so the intensity of the light incident on the power generation layer 25 increases, and the power generation efficiency of the solar cell module 52 is further improved.

[0071] Moreover, the resin that is the material of the light reflecting portion 61 has a smaller elastic modulus than the glass that is the material of the transparent substrate 20, and therefore functions as a stress relaxation layer that relieves the stress applied to the transparent substrate 20. This makes it possible to prevent the transparent substrate 20 from cracking during the manufacture and use of the solar cell module 52, thereby improving the durability of the solar cell module 52.

[0072] The material of the light reflecting portion 61 is not limited to silicone resin, but may be any of polycarbonate, epoxy resin, fluororesin, and engineering plastic.

[0073] Third embodiment In this embodiment, acrylic resin is used as the material of the light reflecting portion 61 (see FIG. 13). SS-101 Super Clear manufactured by Epoch Corporation is used as the acrylic resin. The refractive index of this acrylic resin is 1.51. The rest is the same as in the second embodiment.

[0074] (Fourth embodiment) Fig. 14 is an enlarged cross-sectional view of a solar cell module 52 according to this embodiment. In Fig. 14, the same elements as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof will be omitted below.

[0075] As shown in Fig. 14, in this embodiment, a material mixed with a light reflecting filler 62 is used for the light reflecting portion 61. Note that the light reflecting filler 62 may be made of metal or glass instead of titanium oxide. In addition, POS Seal (white), which is a silicone resin made by Cemedine Co., Ltd., is used for the light reflecting portion 61. The refractive index of this silicone resin is 1.41. The rest is the same as in the second embodiment.

[0076] By mixing the light reflecting filler 62 into the light reflecting portion 61 in this manner, the light L that enters the light reflecting portion 61 is reflected inside the light reflecting portion 61 and enters the power generation layer 25. Therefore, the light L can be efficiently guided to the power generation layer 25, and the power generation efficiency of the solar cell module 52 can be further improved.

[0077] Furthermore, since the light scattered inside the light reflecting portion 61 in this manner is incident on the power generation layer 25 of the solar cell 50 adjacent to the light reflecting portion 61, the amount of light incident on the power generation layer 25 increases, improving the power generation efficiency of the solar cell module 52.

[0078] Fifth embodiment In this embodiment, silicone rubber is used as the material of the light reflecting portion 61 (see FIG. 13). As the silicone rubber, one-liquid type RTV rubber (clear) manufactured by Shin-Etsu Chemical Co., Ltd. is used. The refractive index of the silicone rubber is 1.41. The rest is the same as in the second embodiment.

[0079] Silicone rubber has an extremely small elastic modulus compared to other resins, so that the light reflecting portion 61 can flexibly deform in response to stress applied to the transparent substrate 20, and can function as a stress relaxation layer that relieves the stress.

[0080] (Other embodiments) Fig. 15 is an enlarged cross-sectional view of a solar cell module 52 according to this embodiment. In Fig. 15, the same elements as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof will be omitted below.

[0081] As shown in FIG. 15, in this embodiment, a reflective layer 59 is provided on the side surface 20s of the transparent substrate 20. The reflective layer 59 is a metal oxide layer such as titanium oxide having a thickness of about 0.1 μm. This increases the reflectivity on the side surface 20s compared to when the reflective layer 59 is not provided, so that the light L can be almost certainly reflected by the side surface 20s and guided to the power generation layer 25, thereby further improving the power generation efficiency of the solar cell module 52. Moreover, the metal oxide layer is not glossy like a metal layer, so it can scatter light. As a result, the scattered light is incident on each of the power generation layers 25 of the multiple solar cells 50 in a wide range, and the light can be effectively used in each solar cell 50.

[0082] FIG. 16 is an enlarged cross-sectional view of a solar cell module 52 according to still another example of this embodiment. In this example, similarly to the second embodiment, the gaps between adjacent solar cells 50 are filled with resin as light reflecting portions 61. This allows the light reflecting portions 61 to function as a stress relaxation layer, so that the stress applied to the transparent substrate 20 can be relaxed by the light reflecting portions 61, and the transparent substrate 20 can be prevented from cracking due to the stress.

[0083] The inventors of the present application fabricated solar cell modules 52 according to the above first to fifth embodiments, and conducted experiments to investigate the amount of power generated by the solar cell modules 52. The experiments will be described below. (First Experimental Example) In this example, the solar cell 50 was fabricated according to the first embodiment. The transparent substrate 20 had sides Ax and Ay of 15 mm and a thickness Az of 1.1 mm. The transparent electrode layer 21 had a thickness of 0.3 μm. An alcohol solution prepared from titanium alkoxide was applied onto the transparent electrode layer 21 in the cell region Rc, and the alcohol solution was then heated to 550° C. and dried to form a reverse electron transfer prevention layer 22 with a thickness of 0.005 μm to 0.01 μm.

[0084] Furthermore, a titanium paste containing titanium oxide particles of 40 nm was applied to a thickness of 5 μm to 10 μm on the reverse electron transfer prevention layer 22, and the paste was heated to 550° C. to remove organic components, thereby forming the power generation layer 25. Furthermore, CYC-B11(K) was added as a dye to an organic solvent obtained by mixing acetonitrile and t-butanol in a volume ratio of 1:1. Then, while keeping the organic solvent at 50° C., the transparent substrate 20 was immersed in the organic solution for 4 hours, thereby allowing the dye to be adsorbed on the power generation layer 25. The concentration of the dye in the organic solvent was 0.2 mM.

[0085] Then, iodine, 1,3-dimethylimidazolium iodide (DMII), acetonitrile, and polyethylene oxide having a molecular weight of 1 million were mixed uniformly to prepare a solid electrolyte precursor 26. Then, 20 μL of the solid electrolyte precursor 26 was dropped onto the power generation layer 25, and the power generation layer 25 was heated to 100° C. The heating time was 100° C. and the heating time was 5 minutes. As a result, the excess acetonitrile contained in the solid electrolyte precursor 26 was volatilized, and a solid electrolyte layer 27 was obtained. Then, the power generation layer 25 was returned to room temperature.

[0086] Next, a counter electrode layer 33 formed by forming a platinum layer with a thickness of 0.05 μm on a titanium foil with a thickness of 100 μm was adhered to the solid electrolyte layer 27. Then, a silane coupling layer with a thickness of 0.5 μm was formed as an adhesion layer 40 on each side surface of the transparent substrate 20 and on each of the counter electrode layers 33 except for the second electrode region R2. Furthermore, a sealing portion 41 with a thickness of 150 μm was formed on the adhesion layer 40 to prepare a solar cell 50. A solar cell module 52 was prepared by connecting eight solar cells 50 in series.

[0087] The inventors of the present application conducted the following investigation to confirm the amount of power generation of this solar cell module 52. In the investigation, the solar cell module 52 was installed in a dark room, and light from a standard LED (Light Emitting Diode) light source was irradiated onto the solar cell module 52 in the dark room. The standard LED light source used was a BLD-100 manufactured by Bunkoki Co., Ltd. Furthermore, to confirm the illuminance of the light, the light receiving section of a portable illuminometer HD2102.1 manufactured by DeltaOhm was placed directly under the standard LED light source.

[0088] Under these conditions, when the solar cell module 52, which is made up of eight solar cells 50 connected in series, was irradiated with light of 200 Lux, the amount of power generated by the solar cell module 52 was 53.7 μW. Moreover, the amount of power generated by light of 1000 Lux was 268.2 μW.

[0089] (Second Experimental Example) In this example, the solar cell module 52 was produced according to the second embodiment. As the silicone resin that is the material of the light reflecting portion 61, a silicone sealant (clear) manufactured by Cainz Corporation with a refractive index of 1.41 was used.

[0090] The inventors of the present application investigated the power generation amount of the solar cell module 52 according to this example under the same conditions as in the first experimental example. As a result, the power generation amount for light of 200 Lux was 54.0 μW, and the power generation amount for light of 1000 Lux was 270.2 μW.

[0091] (Third Experimental Example) In this example, the solar cell module 52 was produced according to the third embodiment. As the acrylic resin that is the material of the light reflecting portion 61, SS-101 Super Clear manufactured by Epoch Corporation, which has a refractive index of 1.51, was used.

[0092] The inventors of the present application investigated the power generation amount of the solar cell module 52 according to this example under the same conditions as those of the first experimental example. As a result, the power generation amount for light of 200 Lux was 54.1 μW, and the power generation amount for light of 1000 Lux was 272.9 μW.

[0093] (Fourth Experimental Example) In this example, the solar cell module 52 was produced according to the fourth embodiment. Titanium oxide particles were used as the light reflecting filler 62 to be mixed into the light reflecting portion 61. As the silicone resin which is the material of the light reflecting portion 61, a POS seal (white) manufactured by Cemedine Co., Ltd. with a refractive index of 1.41 was used.

[0094] The inventors of the present application investigated the power generation amount of the solar cell module 52 according to this example under the same conditions as those of the first experimental example. As a result, the power generation amount for light of 200 Lux was 54.5 μW, and the power generation amount for light of 1000 Lux was 274.3 μW.

[0095] (Fifth Experimental Example) In this example, the solar cell module 52 was produced according to the fifth embodiment. As the silicone rubber which is the material of the light reflecting portion 61, a one-liquid type RTV rubber (clear) having a refractive index of 1.41 manufactured by Shin-Etsu Chemical Co., Ltd. was used.

[0096] The inventors of the present application investigated the power generation amount of the solar cell module 52 according to this example under the same conditions as those of the first experimental example. As a result, the power generation amount for light of 200 Lux was 54.2 μW, and the power generation amount for light of 1000 Lux was 272.4 μW.

[0097] (Comparative Example) In this comparative example, the length Ax of the long side of the transparent substrate 20 (see FIG. 4(a)) was set to 60 mm, and the length Ay of the short side was set to 30 mm, to fabricate a solar cell 50 having a larger cell region Rc than that of the first experimental example. In this case, the power generation area in this comparative example is almost equal to the power generation area of ​​a solar cell module 52 in which eight solar cells 50 are connected in series as in the first experimental example. Then, the amount of power generated by a single solar cell 50 according to this comparative example was measured. The measurement conditions were the same as those in the first experimental example. As a result, the amount of power generated for light of 200 Lux was 48.4 μW, and the amount of power generated for light of 1000 Lux was 243.5 μW. These values ​​are smaller than those in each of the first to fifth experimental examples. As a result, it was confirmed that the side surfaces 20s of the multiple transparent substrates 20 facing each other as in the first to fifth embodiments is effective in improving power generation efficiency.

[0098] Although each embodiment has been described in detail above, the present invention is not limited to the above. For example, although a dye-sensitized solar cell is manufactured as the solar cell 50 in the above, a silicon solar cell may be manufactured as the solar cell 50. [Explanation of symbols]

[0099] 1, 50 Solar cell 2, 20 Transparent substrate 3, 21 Transparent electrode layer 4, 22 Reverse electron transfer prevention layer 5, 25 Power generation layer 6, 27 Solid electrolyte layer 7, 33 Counter electrode 8, 41 Sealing part 11. Solar cell module 20s side 31 Metal foil 32 Catalyst layer 40 Adhesion layer 51 Wiring board 52 Solar cell module 53 Secondary battery 54 Radio circuit 55 Sensors 59 Reflective layer 61 Light reflecting part 62 Light-reflecting filler

Claims

1. a transparent substrate having a first side, a second side, and a main surface; a power generation layer provided on a main surface of the transparent substrate; a sealing portion provided to cover at least the first side surface, the second side surface, and a side surface of the power generation layer; having the sealing portion is in contact with and covers the first side surface and the second side surface, A plurality of the transparent substrates are provided, the plurality of transparent substrates are arranged such that the first side surface and the second side surface face each other; A solar cell module, comprising: a light reflecting portion having a refractive index different from that of the transparent substrate, the light reflecting portion being provided between the first side surface and the second side surface.

2. The solar cell module according to claim 1 , wherein the light reflecting portion includes a resin.

3. 3. The solar cell module according to claim 2, wherein the resin is any one of an acrylic resin, a polycarbonate, an epoxy resin, a silicone resin, a fluororesin, and an engineering plastic.

4. 3. The solar cell module according to claim 2, wherein a silane coupling layer is provided on the first side surface, and the light reflecting portion is provided on the silane coupling layer.

5. 5. The solar cell module according to claim 1, wherein the light reflecting portion includes a light reflecting filler.

6. 6. The solar cell module according to claim 1, further comprising a reflective layer provided on the first side surface.

7. The solar cell module according to claim 6 , wherein the reflective layer is a metal oxide layer.

8. 8. The solar cell module according to claim 1, wherein the sealing portion includes a resin.

9. 9. The solar cell module according to claim 1, wherein the power generation layer is a layer of a plurality of semiconductor particles having a dye adsorbed on the surface thereof.

10. A transparent substrate having a first side, a second side, and a main surface; a power generation layer provided on a main surface of the transparent substrate; a sealing portion provided to cover at least the first side surface, the second side surface, and a side surface of the power generation layer; having the sealing portion is in contact with and covers the first side surface and the second side surface, A plurality of the transparent substrates are provided, the plurality of transparent substrates are arranged such that the first side surface and the second side surface face each other; A solar cell module, comprising: a reflective layer provided on the first side surface.

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