JPH09191115A - Solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contamination retardant solar cell module in which direct reflection on the surface is reduced while suppressing the creasing by forming at least two coating material layers, i.e., a transparent organic polymer resin layer and a transparent surface protective film layer, sequentially on the light incident side surface of a photovoltaic element and specifying the pitch of three contiguous protrusions/recesses on the surface of coating material. SOLUTION: A photovoltaic element 101 is coated, on the light incident side surface, with at least two coating material layers, i.e., a transparent organic polymer resin layer 102 impregnated with a fibrous inorganic compound and an outermost transparent surface protective film layer 103 formed contiguously thereto. The surface protective film layer 103 is preferably composed of a fluororesin and protrusions/recesses 106 are formed on the surface. The protrusions/recesses 106 are preferably formed such that following relationships are satisfied; 200μm<|Xn -Xn+2 |<500μm, Xn+2 /Xn <0.9 or Xn+2 /Xn >1.1, where Xn , Xn+1 and Xn+2 represent the pitch of three adjacent protrusions/recesses (distance between the bottoms of recess or the peaks of protrusion) selected arbitrarily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved solar cell module, and more particularly, to a light incident side surface of a photovoltaic element,
The present invention relates to a solar cell module in which a transparent organic polymer resin layer and an outermost surface thereof in contact with the transparent organic polymer resin layer are coated with at least two transparent surface protective film layers.

[0002]

2. Description of the Related Art In recent years, awareness of environmental problems has been increasing worldwide. Above all, the fear of global warming caused by CO ₂ emission is serious, and the demand for clean energy is increasing more and more. Under these circumstances, solar cells are expected as a clean energy source because of their safety and ease of handling. By the way, there are various forms of solar cells.
Typical examples include crystalline silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, copper indium selenide solar cells, and compound semiconductor solar cells. Among these, thin film crystalline silicon solar cells, compound semiconductor solar cells, and amorphous silicon solar cells can be made large in area at a relatively low cost, and therefore, research and development are being actively pursued in various fields.

Among these solar cells, a thin film solar cell typified by an amorphous silicon solar cell in which silicon is deposited on a conductive metal substrate and a transparent conductive layer is formed on the conductive metal substrate is lightweight and has impact resistance and flexibility. Since it is rich in nature, it is regarded as a promising future module form. However, unlike the case of depositing silicon on a glass substrate, it is necessary to cover the light incident side surface with a transparent coating material to protect the solar cells, and therefore the surface coating material requires the following items. . That is, it has good transparency (transparency) in the visible light region used for solar cell power generation, and protects the internal photovoltaic element from stress such as scratches and impacts from the outside (resistant). (Scratchability), it is required that the coating material itself be less deteriorated (weather resistance) and that the coating material itself is hard to burn (flame retardancy) at the same time as protecting the photovoltaic element in an outdoor installation environment. .

As the surface coating material satisfying such conditions, generally, the outermost surface coating material is a fluororesin film such as glass or acrylic resin film, tetrafluoroethylene-ethylene copolymer film, polyvinyl fluoride film or fluorine. A transparent fluoride polymer thin film using a resin paint or the like is used. Then, various transparent organic polymer resins such as ethylene-vinyl acetate copolymer are used on the inside as a filler. As the filler, EVA, which is inexpensive and can be used in a large amount to protect the internal photovoltaic element, is used as a transparent organic polymer resin excellent in heat resistance and weather resistance. There are many. However, when glass is used as the outermost surface coating material, since glass is heavy, inflexible, and expensive, the advantages such as light weight, flexibility, and low cost, which are features of amorphous silicon solar cells in particular. Can't save Therefore, in an amorphous silicon solar cell, a transparent fluoride polymer thin film is often used as the outermost surface coating material. Fluoride polymer thin film is rich in weather resistance and water repellency, and can reduce decrease in conversion efficiency of solar cell module due to yellowing / white turbidity due to deterioration of resin or decrease in light transmittance due to surface stain. In addition, the solar cell module can be made more flexible.

As described above, the conventional solar cell module using the resin film as the outermost surface coating has a smooth surface. In the solar cell module, light incident on the smooth surface at an angle close to parallel is totally reflected when it exceeds the critical angle, and the light does not enter the photovoltaic element of the solar cell. It becomes impossible to generate a large electromotive force. Furthermore, when the solar cell module is installed on the roof of a house, the roof of a building, a wall surface, etc., the reflected light reaches other houses or the ground depending on the angle, so that people there are dazzled and uncomfortable. Problems such as feeling occur. In addition, when the outermost surface is covered with a film, there is a problem that the film is easily wrinkled. For example, a method of vacuum heating and pressure bonding using a laminator is generally used to attach the film to the organic resin in the coating material forming step, but wrinkles may occur when the film is loosened during the pressure bonding. Even if the initial appearance is good, wrinkles may occur on the surface film due to repeated thermal expansion and contraction of the covering material after long-term outdoor exposure. Furthermore, if the surface is smooth, even small wrinkles are conspicuous and the appearance is likely to be poor.

As means for solving the above-mentioned drawbacks,
Unevenness is provided on the surface of a solar cell module. Usually, a metal mesh such as an aluminum mesh or a stainless mesh or a woven cloth is often used, and its shape is a regular lattice pattern. JP-A-60-88481 discloses a solar cell module in which the surface roughness Rmax of the surface protective layer is 0.3 to 100 μm. In the publication, since the surface roughness is set to the above value in the solar cell module, the electromotive force is insufficient even if it is used in a state where the light amount is small and the incident angle is large such as in the early morning or the evening. It is said that there is an effect that does not occur. FIG. 7 is a conventional example showing a coating configuration of such a solar cell module. In FIG. 7, 703 is a fluoride polymer thin film layer, 7
02 is a transparent organic polymer resin, 701 is a photovoltaic element, 7
Reference numeral 04 is an insulating film. More specifically, the fluoride polymer thin film layer 703 is a fluororesin film such as an ETFE (ethylene-tetrafluoroethylene copolymer) film or a PVF (polyvinyl fluoride) film, and the transparent organic polymer resin 602 is EVA. (Ethylene-vinyl acetate copolymer), butyral resin and the like. The insulating film 704 is an organic resin film such as a 7 nylon film, a PET (polyester) film, and an aluminum laminated Tedlar film.

However, as described above, the solar cell module using the resin film as the outermost surface coating material is
There is a problem that dirt is more likely to adhere to and accumulate on the surface during outdoor use, as compared with a solar cell module using glass. As a result, the transparency of the surface coating material is reduced, the incident light reaching the photovoltaic element is reduced, that is, the photovoltaic power is reduced. Further, when it is used as a part of a building material such as a roof or a wall of a house, it is not preferable in terms of appearance. Moreover, although the dirt attached to and accumulated on the surface of the solar cell module is usually removed to some extent by the natural environment such as rain, snow, wind, etc. Is inferior. As described above, the solar cell module using the resin film as the outermost surface coating material has a problem that dirt easily adheres to and accumulates on the solar cell module and is hard to be removed. Then, in particular, in the conventional solar cell module having regular grid-like irregularities on the surface, there is a problem that the degree thereof is remarkable and the reduction of electromotive force is large. As described above, in JP-A-60-88481, the surface roughness Rmax of the surface protective layer is 0.3 to 10.
A solar cell module of 0 um is disclosed, and the solar cell module has an effect of not causing a shortage of electromotive force even when used in a state where the amount of light is small and the incident angle is large such as in the early morning and the evening. Have been described. However, this publication only mentions solar cell modules used in devices such as electric desk calculators, and does not mention solar cell modules used outdoors for electric power applications. . That is, there is no mention of the above-mentioned drawbacks that are particularly problematic in outdoor electric power applications, that is, the degree of adhesion of dirt on the surface coating layer, the extent of dirt removal, and the like. Also,
There is no suggestion about the pitch of surface irregularities. From the technical matters described in the above publication, when the pitch of the unevenness is extremely large, it becomes nearly smooth, and the influence of the reflected light on the surroundings,
Problems such as wrinkles on the surface film cannot be solved. Further, when the pitch is extremely narrow, it is very difficult for dirt to be removed. Furthermore, the publication does not rub the pitch regularity at all. If there are irregularities with regularity, defects such as wrinkles during solar cell production stand out,
Yield deteriorates. For this reason, the shape of the surface covering material that solves the above-mentioned problems associated with the solar cell module for electric power using the film and the sealing resin as the surface covering material is not known.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the conventional solar cell module,
An object of the present invention is to provide an improved solar cell module having high reliability even in long-term outdoor use. Another object of the present invention is to provide a highly reliable solar cell module which has less direct reflected light on the surface, is less likely to have wrinkles on the surface film, is less likely to be stained even when used outdoors for a long time, and is easily removed. is there.

[0009]

Means for Solving the Problems The present inventors have conducted extensive research and development to solve the above problems. As a result, it has been found that the above object can be achieved by the following. That is, the solar cell module in which the light incident side surface of the photovoltaic element is covered with at least two transparent organic polymer resin layers and the outermost surface of the transparent organic polymer resin layer, which is a transparent surface protective film layer, at least two layers. In the above, the surface of the coating material is provided with concavities and convexities, and the pitches of the three concavities and convexes arbitrarily selected among them (the vertices of the concave portions or the distances between the vertices of the convex portions) are respectively X _n , X _{n + 1} and X _{n +. 2} is set to 20 μm <| X _n −X _{n + 2} | <500 μm, and X _{n + 2} / X _n <0.9 or X _{n + 2} / X _n > 1.1.
And

[0010]

The solar cell module based on the above-described structure has the following effects and exhibits remarkable effects. (1) Direct reflected light on the surface is reduced, sufficient electromotive force can be obtained, wrinkles are not left on the outermost surface resin film during production, and color unevenness due to uneven semiconductor film thickness of the photovoltaic element is conspicuous. Since it is eliminated, the production yield is improved. In addition, when used outdoors, the adhesion of dirt to the surface covering material is inconspicuous, and it becomes a particularly beautiful aesthetic solar cell module when it is incorporated as a building material on the roof, wall, etc. of a house. . That is, since the pitch of the irregularities is irregular, appearance defects such as wrinkles can be absorbed and made inconspicuous. At the same time, even if dirt is attached, the solar cell module can be made inconspicuous in appearance. (2) By setting the pitch of the concavities and convexities to 50 μm to 500 μm, the degree of adhesion of dirt to the surface coating material can be reduced, and at the same time wrinkles on the surface during use can be prevented. That is, when the pitch of the unevenness is 50 μm or more, the degree of contamination can be reduced, and when it is 500 μm or less, the phenomenon of wrinkles on the surface during outdoor use can be prevented. (3) When the heights of three adjacent irregularities (height differences between adjacent convex portions of concave portions) arbitrarily selected are Y _n , Y _{n + 1} and Y _{n + 2} , 10 μm <| Y _n −Y _{n + 2} | <200 μm and Y _n / Y _{n + 2} <0.9 or Y _n / Y _{n + 2} > 1.1
With this, the effect described in (1) above can be enhanced, and wrinkles and stains on the surface covering material can be made less noticeable. That is, since the height of the irregularities does not have regularity, defects in appearance can be further absorbed, so that a solar cell module having an excellent appearance can be obtained. (4) By setting the height of the unevenness to be 10 μm to 300 μm, it is possible to enhance the effect described in (2) above and reduce the adhesion of dirt and the prevention of wrinkles during use.

(5) The unevenness has a length of 50 μm to 200 mm
By being formed by the overlapping of the lines, the adhered dirt can be removed by natural purification. That is, since it is not a grid-like concavo-convex pattern, dirt easily flows due to a natural environment such as rain. (6) The diameter of the wire forming the unevenness is 0.1 mm to 3 mm
By this, stains are less likely to accumulate on the irregularities, and even if they are attached, they can be easily removed. That is, if the uneven groove formed by the line is not too thin, dirt is unlikely to be deposited on that portion and is easily removed. (7) By forming the transparent resin film layer from a fluoride polymer, the coating has excellent weather resistance. That is, the weather resistance of the fluoride polymer can be expected in combination with the transparent organic polymer resin of the filler. (8) A coating material that makes use of the weather resistance, transparency, and mechanical strength of the tetrafluoroethylene-ethylene copolymer is achieved by converting the fluoride polymer into a tetrafluoroethylene-ethylene copolymer. To be done. (9) ASTM D-882 of the transparent resin film layer
In the test method, the tensile elongation at break was the wetting index of the vertical outermost surface transparent resin film layer on the photovoltaic element side of 35 dyne.
By the above, a coating material having excellent adhesive strength and high long-term reliability can be obtained. That is, not only to optimize the resin film and the transparent organic polymer resin to improve the adhesive force between the resin film and the transparent organic polymer resin in the initial stage,
It is a coating material that has high reliability in terms of adhesive strength even after long-term outdoor exposure.

(10) The tensile breaking elongation in the ASTM D-882 test method is 200 in both the machine direction and the machine direction.
% To 800%, the outermost surface coating material does not have cracks, so that intrusion of water from the outside can be prevented and electric insulation from the outside can be secured. Further, the surface film is locally crystallized by the local stretching treatment, whereby the moisture permeability is lowered, or volatilization of internal additives is prevented and moisture resistance and weather resistance are improved. (11) Since the transparent organic polymer resin is an ethylene-vinyl acetate copolymer (EVA), it is the most used resin as a coating material for a conventional solar cell module, and the present coating material composition. It is possible to obtain the above-mentioned effect without significantly changing the. (12) Since the transparent organic polymer resin is treated with a coupling agent, the adhesive strength between the outermost surface transparent resin film, the photovoltaic element substrate and the fibrous inorganic compound is improved, and high reliability as a covering material is obtained. You can secure the sex. (13) By impregnating the transparent organic polymer with a fibrous inorganic compound, a high scratch resistance can be secured by a small amount of the transparent organic polymer resin. That is, by reinforcing with a fibrous inorganic compound, a coating material having a high resistance to scratches from the outside can be obtained with a very small amount of a transparent organic polymer resin. (14) Since the fibrous inorganic compound is treated with the coupling agent, the adhesive strength with the transparent organic polymer resin can be further improved, and the fibrous inorganic compound can be prevented from rising.

[0013]

Embodiment Examples The present invention will be described with reference to the following embodiment examples. An example of the solar cell module of the present invention is shown in a plan view of FIG. 1 (A) and a sectional view of FIG. 1 (B). In FIG. 1 (A) and FIG. 1 (B), 101 is a photovoltaic element, 10
2 is a transparent organic polymer compound impregnated with a fibrous inorganic compound, 103 is a transparent resin film located on the outermost surface, 1
Reference numeral 04 is a backside filler, and 105 is a backside insulating film. Light from the outside enters from the film 103 on the outermost surface, reaches the photovoltaic element 101, and the generated electromotive force is extracted to the outside from an output terminal (not shown). Reference numeral 106 denotes unevenness provided on the surface coating material. A typical photovoltaic element 101 according to the present invention has a semiconductor photoactive layer as a light conversion member and a transparent conductive layer formed on a conductive base. A schematic configuration diagram as an example thereof is shown in FIG. In FIG. 2, 201 is a conductive substrate, 202 is a back reflection layer, 20
3 is a semiconductor photoactive layer, 204 is a transparent conductive layer, 205 is a collector electrode, and 206 is an output terminal.

The conductive substrate 201 serves as a substrate for the photovoltaic element, and also serves as a lower electrode. Materials include silicon, tantalum, molybdenum, tungsten,
Examples include stainless steel, aluminum, copper, titanium, carbon sheets, lead-plated steel sheets, resin films having a conductive layer formed thereon, and ceramics. On the conductive substrate 201, a metal layer, a metal oxide layer, or a metal layer and a metal oxide layer may be formed as the back surface reflection layer 202. For example, Ti, Cr, Mo, W, A
For example, ZnO, TiO ₂ , SnO ₂ or the like is used for the metal oxide layer. Examples of a method for forming the metal layer and the metal oxide layer include a resistance heating evaporation method, an electron beam evaporation method, and a sputtering method.

The semiconductor photoactive layer 203 is a portion for performing photoelectric conversion, and as a concrete material, pn junction type polycrystalline silicon, pin junction type amorphous silicon, or Cu.
InSe ₂ , CuInS ₂ , GaAs, CdS / Cu
₂ S, CdS / CdTe, CdS / InP, CdTe /
And a compound semiconductor such as Cu ₂ Te. These semiconductor photoactive layers can be formed by a known method. That is, in the case of polycrystalline silicon, a sheet of molten silicon or heat treatment of amorphous silicon is used. In the case of amorphous silicon, plasma CV using silane gas as a raw material.
In the case of D, a compound semiconductor, it can be formed by a method such as ion plating, ion beam deposition, vacuum deposition method, sputtering method, and electrodeposition method.

The transparent conductive layer 204 functions as the upper electrode of the solar cell. As the material used, for example, I
_{n 2 O 3, SnO 2,} In 2 O 3 -SnO 2 (ITO), Zn
There are O, TiO ₂ , Cd ₂ SnO ₄ , and a crystalline semiconductor layer doped with a high concentration of impurities. Examples of the formation method include resistance heating evaporation, sputtering, spraying, CVD, and impurity diffusion.

A grid-shaped collector electrode 205 (grid) may be provided on the transparent conductive layer in order to collect current efficiently. As a specific material of the current collecting electrode 205, for example, Ti, Cr, Mo, W, Al, Ag, Ni, C
u, Sn, or a conductive paste such as a silver paste. As a method for forming the current collecting electrode 205, sputtering using a mask pattern, resistance heating, a CVD method, a method in which an unnecessary portion is removed by etching after depositing a metal film on the entire surface and patterning is performed,
There are a method of directly forming a grid electrode pattern by photo-CVD, a method of forming a mask of a negative pattern of the grid electrode pattern and then plating, and a method of printing a conductive paste. The conductive paste is usually a fine powder of silver, gold, copper, nickel, carbon, etc. dispersed in a binder polymer. Examples of the binder polymer include resins such as polyester, epoxy, acrylic, alkyd, polyvinyl acetate, rubber, urethane, and phenol.

An output terminal 206 for taking out electromotive force is attached to the conductive substrate and the collecting electrode. A method of spot-welding a metal body such as a copper tab or joining with a solder 207 is used for the conductive substrate, and a method of electrically connecting the metal body with a conductive paste or solder 207 is used for the collecting electrode. Note that it is desirable to provide an insulator 208 in order to prevent the output terminal from coming into contact with the conductive metal substrate or the semiconductor layer and short-circuiting when the collector terminal 205 is attached to the collector electrode 205. The photovoltaic elements formed as described above are connected in series or in parallel depending on the desired voltage or current. In the case of series connection, the plus side and the minus side of the output terminal are connected, and in the case of parallel connection, the same polarity is connected. Alternatively, a desired voltage or current can be obtained by integrating a photovoltaic element on an insulated substrate. The material of the metal member used for connecting the output terminal and the element may be selected from copper, silver, solder, nickel, zinc and tin in consideration of high conductivity, solderability and cost. desirable.

The outermost surface resin film 103 used in the present invention and the transparent organic polymer resin 102 impregnated with the fibrous inorganic compound used as the surface filler will be described below. The transparent organic polymer resin used as the surface filler 102 covers the irregularities of the photovoltaic element with a resin, protects the element from a harsh external environment such as temperature change, humidity, and shock, and protects the surface film and the element. Necessary to secure the adhesion of. Therefore, weather resistance, adhesiveness,
Fillability, heat resistance, cold resistance and impact resistance are required. Examples of resins satisfying these requirements include polyolefin resins such as ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA) and butyral resin. , Urethane resin, silicone resin and the like.
Among them, EVA has well-balanced physical properties for use in solar cells, and is preferably used. However, since the heat deformation temperature is low as it is, it easily deforms and creeps under high temperature use. Therefore, it is desirable to increase the heat resistance by crosslinking. In the case of EVA, it is common to crosslink with an organic peroxide. The cross-linking by the organic peroxide is performed by free radicals generated from the organic peroxide extracting hydrogen or halogen atoms in the resin to form a C—C bond. The organic peroxide activation method includes thermal decomposition,
Redox decomposition and ionic decomposition are known. Generally, the thermal decomposition method is preferred. Examples of the organic peroxide include hydroperoxide type, dialkyl (allyl) peroxide type, diacyl peroxide type, peroxyketal type, peroxyester type, peroxycarbonate type and ketone peroxide type.

Specific examples of the hydroperoxide system include:
t-Butyl peroxide; 1,1,3,3-tetramethylbutyl peroxide; p-menthane hydroperoxide; cumene hydroperoxide; p-cymene hydroperoxide; diisopropylbenzene peroxide;
2,5-dimethylhexane 2,5-dihydroperoxide; cyclohexane peroxide; 3,3,5-trimethylhexanone peroxide and the like. Specific examples of the dialkyl (allyl) peroxide type include di-t-
Butyl peroxide; dicumyl peroxide; t-butyl cumyl peroxide and the like.

Specific examples of diacyl peroxides include diacetyl peroxide; dipropionyl peroxide; diisobutyryl peroxide; dioctanoyl peroxide; didecanoyl peroxide; dilauroyl peroxide; bis (3,3,5-trimethylhexanoyl). ) Peroxide; benzoyl peroxide; m-toluyl peroxide; p-chlorobenzoyl peroxide; 2,4-dichlorobenzoyl peroxide; peroxysuccinic acid and the like.

Specific examples of the peroxyketal system include:
2,2-di-t-butylperoxybutane; 1,1-di-t-butylperoxycyclohexane; 1,1-di-
(T-Butylperoxy) -3,3,5-trimethylcyclohexane; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane; 2,5-dimethyl-2,5
-Di (t-butylperoxy) hexyne-3; 1,3-
Di (t-butylperoxyisopropyl) benzene;
2,5-Dimethyl-2,5-dibenzoylperoxyhexane; 2,5-dimethyl-2,5-di (peroxybenzoyl) hexyne-3; n-butyl-4,4-bis (t-butylperoxy) valerate And so on.

Specific examples of the peroxy ester type are:
t-butyl peroxyacetate; t-butyl peroxyisobutyrate; t-butyl peroxypivalate;
t-butyl peroxy neodecanoate; t-butyl peroxy 3,3,5-trimethyl hesanoate; t-butyl peroxy 2-ethylhexanoate; (1,1,
3,3-Tetramethylbutylperoxy) 2-ethylhexanoate; t-butylperoxylaurate; t-
Butyl peroxy benzoate; di (t-butyl peroxy) adipate; 2,5-dimethyl 2,5-di (peroxy 2-ethylhexanoyl) hexane; di (t-butyl peroxy) isophthalate; t-butyl peroxymalate; Acetyl cyclohexyl sulfonyl peroxide and the like.

Specific examples of the peroxycarbonate system include t-butylperoxyisopropyl carbonate;
Di-n-propyl peroxydicarbonate; di-se
c-Butylperoxydicarbonate; di (isopropylperoxy) dicarbonate; di (2-ethylhexylperoxy) dicarbonate; di (2-ethoxyethylperoxy) dicarbonate; di (methoxidepropylperoxy) carbonate; di (3-methoxybutylperoxy) ) Dicarbonate; bis- (4-t-butylcyclohexylperoxy) dicarbonate and the like. Specific examples of the ketone peroxide type include acetylacetone peroxide; methyl ethyl ketone peroxide; methyl isobutyl ketone peroxide; ketone peroxide. For other structures, vinyl tris (t-butylperoxy) silane can be used.

The amount of the organic peroxide added is the amount of the filler resin 10
It is 0.5 to 5 parts by weight with respect to 0 parts by weight. By using the organic peroxide in combination with the filler, it is possible to perform crosslinking and thermocompression bonding while heating under pressure. The heating temperature and time can be determined by the thermal decomposition temperature characteristics of each organic peroxide. Generally, thermal decomposition is more than 90%, preferably 95
The heating and pressurization is terminated when the temperature and time for advancing by 10% or more are reached. In order to efficiently carry out the crosslinking reaction, it is desirable to use triallyl isocyanurate (TAIC) called a crosslinking aid. Generally, the addition amount is 1 to 5 parts by weight with respect to 100 parts by weight of the filler resin.

The material of the filler used in the present invention is excellent in weather resistance, but an ultraviolet absorber may be used in combination for further improving the weather resistance or protecting the lower layer of the filler. . As the ultraviolet absorber, a known one can be used, but it is preferable to use a low-volatile ultraviolet absorber in consideration of the use environment of the solar cell module. If a light stabilizer is added at the same time as the ultraviolet absorber, the filler becomes safer against light. Examples of such ultraviolet absorbers include salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ones.

Specific examples of the salicylic acid type include phenyl salicylate; p-tert-butylphenyl salicylate; p-octylphenyl salicylate and the like.
Specific examples of the benzophenone system include 2,4-dihydroxybenzophenone; 2-hydroxy-4-methoxybenzophenone; 2-hydroxy-4-octoxybenzophenone; 2-hydroxy-4-dodecyloxybenzophenone; 2,2'-dihydroxy. -4-methoxybenzophenone; 2,2'-dihydroxy-4,4'-dimethoxybenzophenone;2-hydroxy-4-methoxy-5-sulfobenzophenone; bis (2-methoxy-4)
-Hydroxy-5-benzophenone) methane and the like.

Specific examples of the benzotriazole type compounds include:
2- (2'-hydroxy-5'-methylphenyl) benzotriazole; 2- (2'-hydroxy-5'-te
rt-Butylphenyl) benzotriazole; 2-
(2'-Hydroxy-3 ', 5'-di.tert-butylphenyl) benzotriazole; 2- (2'-hydroxy-3'-tert-butyl-5-methylphenyl)
-5-chlorobenzotriazole; 2- (2'-hydroxy-3 ', 5'-di.tert-butylphenyl)-
5-chlorobenzotriazole; 2- (2'-hydroxy-3 ', 5'-di.tert-amylluphenyl) benzotriazole; 2- {2'-hydroxy-3'-
(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl} benzotriazole; 2,2-methylenebis {4- (1,1,3,3-tetramethylbutyl) -6 -(2H-benzotriazol-2-yl) phenol} and the like.

Specific examples of the cyanoacrylate type include:
2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate; ethyl-2-cyano-3,3'-diphenyl acrylate and the like. One or more of these UV absorbers can be used. A hindered amine-based light stabilizer can be used as a method for imparting weather resistance in addition to the ultraviolet absorber. A hindered amine-based light stabilizer does not absorb ultraviolet rays unlike an ultraviolet absorber, but exhibits a remarkable synergistic effect when used in combination with an ultraviolet absorber. The amount added is generally about 0.1 to 0.3 parts by weight with respect to 100 parts by weight of the resin. Of course, some other than hindered amines function as light stabilizers, but are often colored, which is not desirable for the filler of the present invention.

Specific examples of the hindered amine-based light stabilizer include dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate; poly [ {6- (1, 1, 3,
3-Tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene}
{2,2,6,6-Tetramethyl-4-piperidyl) imino}]; N, N'-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,
2,2,6,6-Pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate; bis (2,2,6,6-tetramethyl-4-piperidyl)
Sevalate; 2- (3,5-di-tert-4-hydroxybenzyl) -2-n-butylmalonate bis (1,
2,2,6,6-pentamethyl-4-piperidyl) and the like.

Further, an antioxidant may be added to improve heat resistance and heat processability. The proper addition amount is 0.1 to 1 part by weight with respect to 100 parts by weight of the resin. As the antioxidant, a monophenol type, a bisphenol type, a polymer type phenol type, a sulfur type or a phosphoric acid type can be used. Specific examples of monophenols include
2,6-di-tert-butyl-p-cresol; butylated hydroxyanisole; 2,6-di-tert-butyl-4-ethylphenol and the like.

Specific examples of bisphenol-based compounds include 2,
2'-methylene-bis- (4-methyl-6-tert-
Butylphenol); 2,2'-methylene-bis- (4
-Ethyl-6-tert-butylphenol); 4,
4'-thiobis- (3-methyl-6-tert-butylphenol); 4,4'-butylidene-bis- (3-methyl-6-tert-butylphenol); 3,9-bis {1,1-dimethyl- 2- {β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl} 2,4,8,10-tetraoxaspiro} 5,5 undecane and the like.

Specific examples of the high-molecular phenol type include:
1,1,3-tris- (2-methyl-4-hydroxy-
5-tert-butylphenyl) butane; 1,3,5-
Trimethyl-2,4,6-tris (3,5-di-ter
t-butyl-4-hydroxybenzyl) benzene; tetrakis- {methylene-3- (3 ', 5'-di-tert)
-Butyl-4'-hydroxyphenyl) propionate} methane; bis (3,3'-bis-4'-hydroxy-3'-tert-butylphenyl) butyric acid} glycol ester; 1,3,5- Tris (3 ',
5'-di-tert-butyl-4'-hydroxybenzyl) -s-triazine-2,4,6- (1H, 3H, 5
H) trione; such as triphenol (vitamin E).

Specific examples of sulfur compounds include dilauryl thiodipropionate; dimyristyl thiodipropionate; distearyl thiopropionate. Specific examples of the phosphoric acid system include triphenyl phosphite; diphenyl isodecyl phosphite; phenyl diisodecyl phosphite; 4,4'-butylidene-bis- (3-methyl-6-tert-butylphenyl-di-tridecyl) phosphite. Phyto; cyclic neopentane tetrayl bis (octadecyl phosphite); tris (mono and / or diphenyl phosphite; diisodecyl pentaerythritol diphosphite; 9,10-dihydro-9-oxa-10-phosphaphenathrene-10
-Oxide; 10- (3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9
-Oxa-10-phosphaphenanthrene-10-oxide; 10-decyloxy-9,10-dihydro-9-
Oxa-10-phosphaphenanthrene; cyclic neopentanetetraylbis (2,4-di-tert-
Butylphenyl) phosphite; cyclic neopentanetetraylbis (2,6-di-tert-methylphenyl) phosphite; 2,2-methylenebis (4,6)
-Tert-butylphenyl) octyl phosphite and the like.

Further, when the solar cell module is expected to be used in a more severe environment, it is preferable to improve the adhesion between the filler and the photovoltaic element or the surface film. The adhesion can be improved by adding a silane coupling agent or an organic titanate compound to the filler. The addition amount thereof is preferably 0.1 to 3 parts by weight, more preferably 0.25 to 1 part by weight, relative to 100 parts by weight of the filler resin. Furthermore, in order to improve the adhesion between the impregnated fibrous inorganic compound and the transparent organic polymer compound, it is effective to add a silane coupling agent or an organic titanate compound to the transparent organic polymer.

Specific examples of such a silane coupling agent include vinyltrichlorosilane; vinyltris (βmethoxyethoxy) silane; vinyltriethoxysilane;
Vinyltrimethoxysilane; γ-methacryloxypropyltrimethoxysilane; β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; γ-glycidoxypropylmethyldiethoxysilane; N-β (aminoethyl) γ-amino Propyltrimethoxysilane; N-β
(Aminoethyl) γ-aminopropylmethyldimethoxysilane; γ-aminopropyltriethoxysilane; N-
Phenyl-γ-aminopropyltrimethoxysilane; γ
-Mercaptopropyltrimethoxysilane; γ-chloropropyltrimethoxysilane and the like.

In order to suppress the decrease in the amount of light reaching the photovoltaic element as much as possible, the surface filler must be transparent, and specifically, the light transmittance is 80 in the visible light wavelength range of 400 nm to 800 nm. % Or more, and more preferably 90% or more. Also,
In order to facilitate the incidence of light from the atmosphere, the refractive index at 25 ° C. is preferably 1.1 to 2.0,
More preferably, it is 1.1 to 1.6.

The fibrous inorganic compound impregnated in the surface filler will be described below. First, the reason for impregnating the fibrous inorganic compound into the transparent organic polymer resin is as follows. A flame retardant property is required for a solar cell module, particularly a solar cell module installed on a roof or wall of a house. However, when the amount of the transparent organic polymer resin is large, the surface coating material becomes very flammable, and when the amount is small, the internal photovoltaic element cannot be protected from external impact. Therefore,
In order to sufficiently protect the photovoltaic element from the external environment with a small amount of resin, a transparent polymer resin impregnated with a fibrous inorganic compound is used as a surface coating material. Specific examples of such fibrous inorganic compounds include glass fiber nonwoven fabric, glass fiber woven fabric, and glass filler. In particular, it is preferable to use a glass fiber nonwoven fabric. Glass fiber woven fabrics are expensive and are not easily impregnated. Using a glass filler does not improve scratch resistance so much that it is difficult to coat the photovoltaic element with a smaller amount of the transparent organic polymer resin. For long-term use, it is desirable to treat the fibrous inorganic compound with a silane coupling agent or an organic titanate compound in the same manner as that used for the transparent organic polymer resin in order to secure sufficient adhesion.

Surface resin film 10 used in the present invention
Since No. 3 is located on the outermost surface layer of the solar cell module, it is required to have performance such as weather resistance, stain resistance, and mechanical strength for ensuring long-term reliability in outdoor exposure of the solar cell module. Examples of the resin film used in the present invention include fluororesin and acrylic resin.
Of these, fluororesins are preferable because they are excellent in weather resistance and stain resistance. Examples of such a fluororesin include polyvinylidene fluoride resin, polyvinyl fluoride resin, and tetrafluoroethylene-ethylene copolymer. Polyvinylidene fluoride resin is excellent in terms of weather resistance, but ethylene tetrafluoride-ethylene copolymer is excellent in terms of compatibility between weather resistance and mechanical strength and transparency.

In order to improve the adhesiveness with the filler, it is desirable that the surface film is subjected to surface treatment such as corona treatment, plasma treatment, ozone treatment, UV irradiation, electron beam irradiation and flame treatment. Specifically, the wetting index on the photovoltaic element side is preferably 40 dyne to 45 dyne. When the wetting index is 40 dyne or less, the adhesive force between the resin film and the filler is insufficient, so that the filler and the resin film are separated from each other. Further, when a tetrafluoroethylene-ethylene copolymer resin film is used as the resin film, it is difficult to set the wetting index to 45 dyne or more. Further, since the stretched film of the resin film causes cracks, it is preferable that the stretched film is not stretched. Specifically, ASTM D-
The tensile breaking elongation in the 882 test method is preferably 200% to 800% in both the longitudinal and transverse directions. Further, the solar cell module using a resin film on the surface has irregularities 106 formed on the surface.
The purpose is to absorb appearance defects such as wrinkles during production,
It is to make a solar cell module that is aesthetically pleasing and to suppress and absorb wrinkles that occur due to repeated thermal expansion and contraction of the covering material during outdoor use. However, even a solar cell module having a smooth surface and a resin film layer covering the outermost surface is more likely to have dirt attached and deposited, which lowers the photovoltaic power, as compared with a solar cell module coated with glass. Furthermore, providing unevenness on the surface makes it easier for dirt to accumulate in the groove between the unevenness,
It becomes an even more serious problem.

Therefore, as the shape of the unevenness, when the pitches of three adjacently selected unevennesses are X _n , X _{n + 1} and X _{n + 2} , respectively, 20 μm <| X _n −
X _{n + 2} | <500 μm and X _{n + 2} / X _n <0.9
Alternatively, it is preferable that X _{n + 2} / X _n > 1.1. In this case, the pitch means the distance between the apexes of the adjacent concave portions or the apexes of the convex portions. 0.9 <X _{n + 2} / X _n <
When it is 1.1, that is, the pitches of the irregularities are regularly arranged, and wrinkles of the surface resin film are noticeable during production. Further, even if there is unevenness in the film thickness of the semiconductor film of the photovoltaic element, it is difficult to absorb it.
Therefore, both of them reduce the production yield. The pitch of the irregularities is preferably 50 μm to 500 μm.
A lot of dirt adhering to the surface is accumulated in the groove formed by the unevenness. That is, when the thickness is 50 μm or less, many grooves are present, and dirt easily accumulates. Also 50
When the thickness is 0 μm or more, not only the appearance defects such as wrinkles at the time of production cannot be absorbed like the solar cell module having a smooth surface, but also the thermal expansion and contraction of the coating material are repeated during outdoor use. Even in this case, the unevenness formed on the surface does not have the effect of the unevenness that can alleviate the stress applied to the surface film during expansion and contraction and suppress the generation of wrinkles.

Next, the height of the unevenness is 10 μm <| Y _n −Y _n , where Y _n , Y _{n + 1} and Y _{n + 2} are the heights of three adjacent arbitrarily selected unevennesses. ₊₂ | <200 μm and Y _n / Y _{n + 2} <0.9 or Y _n / Y _{n + 2} > 1.1
However, it is desirable. Here, the height of the unevenness is the distance between the apex of the left concave portion and the apex of the adjacent right convex portion. When 0.9 <Y _n / Y _{n + 2} <1.1, that is, when irregularities of the same size are regularly arranged, they have the same reflection angle, so when observing the solar cell module from a certain direction, The accumulation of dirt on the surface is very noticeable. Further, the height of the irregularities is preferably 10 μm to 300 μm. When the height of the irregularities is 10 μm or less, the surface becomes close to a smooth surface, and the effect of absorbing wrinkles and appearance defects is lost. When the height is 300 μm or more, the surface resin film is excessively stretched, so May crack at the bottom.

The length of the groove formed by such unevenness is preferably 50 μm or more, and more preferably, the surface of the solar cell module is traversed from end to end. When the length of the groove is 50 μm or less, the accumulated dirt is not removed by the natural environment while being accumulated in the concave portion. When unevenness is provided so as to cross the surface of the solar cell module from one end to the other, dirt accumulated by water such as rain can flow down along the groove. The way in which this dirt flows is very closely related to the diameter of the groove. That is, the diameter of the groove forming the unevenness is 0.1
It is desirable that the thickness is 3 mm to 3 mm. If it is 0.1 mm or less, the accumulated dirt is hard to flow off, and if it is 3 mm or more, the area of the groove, that is, the concave portion becomes large, and the scratch resistance deteriorates. This is because the thickness of the surface filling material of the concave portion is smaller than that of the convex portion, and is therefore weak against external impact. As a method of forming the above-mentioned desired unevenness on the surface coating material, it may be provided during the coating forming step, or may be provided by a method such as pressing after the coating is formed. In addition, as a material for applying unevenness, a chopped strand mat, a glass nonwoven fabric such as a continuous strand mat, an aluminum or stainless steel plate with a pattern engraved in advance,
Nonwoven fabrics of organic fibers and the like can be mentioned.

The insulating film 105 is used for the photovoltaic element 10
It is necessary to maintain electrical insulation between the conductive metal substrate 1 and the outside. As a material, it is possible to secure sufficient electrical insulation with a conductive metal substrate, and also has excellent long-term durability and thermal expansion,
A material having flexibility and capable of withstanding heat shrinkage is preferable. Examples of suitable films include nylon, polyethylene terephthalate, and polycarbonate. The back surface filler 104 is for bonding the photovoltaic element 101 and the back surface insulating film 105. As the material, a material that can secure sufficient adhesiveness to the conductive substrate, has excellent long-term durability, can withstand thermal expansion and thermal contraction, and has flexibility is preferable. Suitable materials used include hot-melt materials such as EVA and polyvinyl butyral, double-sided tapes, and epoxy adhesives having flexibility. Further, it is often the same material as the transparent polymer resin used as the surface filler 102. A reinforcing plate may be attached to the outside of the coating film on the back surface in order to increase the mechanical strength of the solar cell module or to prevent distortion and warpage due to temperature change. For example, a steel plate, a plastic plate, or an FRP (glass fiber reinforced plastic) plate is preferable.

In order to obtain a solar cell module using the above-mentioned photovoltaic element, filler, front surface resin film and back surface coating material, for example, the following method can be adopted. In order to cover the light receiving surface of the photovoltaic element, a method is generally used in which a transparent polymer resin 303 molded in a sheet shape is prepared and then heat and pressure bonded to the front and back of the element. The laminated structure at the time of manufacturing the solar cell module is as shown in FIG. That is, the photovoltaic element 301 and the fibrous inorganic compound 30
2, transparent organic polymer resin 303, surface resin film 30
4, the back surface filler 305, the insulating film 306 in the order of the figure,
Alternatively, they are laminated in the reverse order, and they are thermocompression bonded. At this time, a jig 30 for making unevenness on the outer side of the outermost surface covering material
In step 7, unevenness may be formed during thermocompression bonding, or may be performed after the above steps are completed. When the reinforcing plate is provided, it may be stacked on the insulating film via an adhesive and pressure-bonded, which may be performed simultaneously with the above process or after the process. The heating temperature and the heating time at the time of pressure bonding are determined by the temperature and time for the crosslinking reaction to proceed sufficiently.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments. The present invention is not limited to these examples.

[0047]

Embodiment 1

[Production of Photovoltaic Element] An amorphous silicon (a-Si) solar cell (photovoltaic element) having the structure shown in FIG. 2 was produced as follows. Washed stainless steel substrate 201
An Al layer (thickness 5000 Å) and a ZnO layer (thickness 5000 Å) were sequentially formed on the upper surface as a back reflection layer 202 by a sputtering method. Then, an n-type a-Si layer is formed from a mixed gas of SiH ₄ , PH ₃ and H ₂ by a plasma CVD method into SiH ₄
The i-type a-Si layer from a mixed gas between H _2, SiH ₄ and BF
_A p-type microcrystalline μC-Si layer is formed from a mixed gas of ₃ and H ₂ , and the n-layer film thickness 150 Å / i-layer film thickness 4000 Å / p-layer film thickness 100 Å / n-layer film thickness 100 Å / i-layer film thickness 800 Å / A tandem-type a-Si photoelectric conversion semiconductor layer 203 having a layer structure with a p-layer thickness of 100 Å was formed. Next, as the transparent conductive layer 204, an In ₂ O ₃ thin film (film thickness 700 Å) was formed by vapor-depositing In in an O ₂ atmosphere by a resistance heating method. Furthermore, the grid electrode 205 for current collection was formed by screen printing of silver paste. Then, the negative terminal 2
A copper tab was attached to the stainless steel substrate as the 06a using the solder 207, and a tin foil tape was attached to the collector electrode 205 as the positive side terminal 206b with the solder 207. Thus, a plurality of photovoltaic elements were obtained.

[0048]

[Fabrication of Cell Block] A plurality of photovoltaic elements obtained as described above were connected in series to fabricate a solar cell block having a structure shown in FIG. That is, after arranging the photovoltaic elements,
The positive side terminal 408 of one element and the negative side terminal 409 of the other element of the adjacent elements were connected to each other by soldering with a copper tab 407. As a result, a solar cell block in which three elements were serialized was obtained. At this time, the copper tab connected to the output terminal of the end element was turned to the back surface so that the output could be taken out from the hole of the back surface coating layer described later.

[0049]

[Modularization] EVA sheet 503 (manufactured by Springborn Laboratories, trade name: PHOTOCAP A9918P ^*) on the light-receiving surface side of the cell block obtained above ^.
/ 200 rms / 936, thickness 460 μm) and glass fiber non-woven fabric (manufactured by Honshu Paper Co., Ltd., trade name: Grasper GMC)
-00-080 (B), basis weight 80 g / m ² , thickness 40
0 μm, binder acrylic resin 4.0 wt. % Content) 50
2 and unstretched ETFE film 504 (manufactured by DuPont, product name: unstretched Tefzel film, thickness of 50 microns, single-sided corona discharge treated product), insulating film 505 as backside coating (manufactured by DuPont, product name: DATEC) , A thickness of 75 μm), the same EVA sheet 503 used as the surface covering material as an adhesive, a galvanized steel plate 506 (zinc-plated steel plate, thickness 0.27 mm) painted in black as a reinforcing plate, and the ETFE film 504. /
EVA503 / glass fiber non-woven fabric 502 / cell block 501 / EVA503 / insulating film 505 / EVA5
03 / Reinforcement plate 506 are sequentially stacked so that the ETFE film 504 is on the upper side, and the release Teflon film 507 for EVA that has protruded is further placed on the outermost surface covering material (manufactured by DuPont, trade name: Teflon PFA film). , Thickness 5
A sheet 508 (manufactured by Fuji Glass Fiber Co., Ltd., trade name: Chopped Strand Mat MC450D, basis weight 450 g / m ² ) for making unevenness through 0 μm) was arranged. While depressurizing and degassing this laminate using a single vacuum evacuation laminating apparatus, the laminate was placed in an oven preheated to 150 ° C. for 100 minutes and heated at 150 ° C. for 30 minutes to obtain a solar cell module. Obtained. In addition,
The EVA sheet used here is widely used as an encapsulant for solar cells, and includes 1.5 parts by weight of a crosslinking agent and 100 parts by weight of an EVA resin (vinyl acetate content 33%) and an ultraviolet absorber. 0.3 parts by weight, 0.1 parts by weight of a light stabilizer, 0.2 parts by weight of an antioxidant, and 1.0 part by weight of a silane coupling agent were mixed. Turn the output terminal to the back of the photovoltaic element in advance, and after laminating,
The output can be taken out from the terminal take-out port that was opened in advance on the galvalume steel plate. Thus, a solar cell module was obtained.

[0050]

Example 2 A solar cell module was prepared in the same manner as in Example 1 except that a continuous strand mat (M8608, Asahi Glass Fiber Co., Ltd., 450 g / m ² ) was used as the sheet for forming irregularities in Example 1. It was made.

[0051]

Third Embodiment In the first embodiment, the sheet for forming the unevenness is formed of an aluminum plate in which a pattern in which all the unevenness crosses the end of the solar cell module is engraved in advance on the plate surface (module The protrusion corresponding to the groove had a width of 250 μm and a height of 50 μm) (see FIG. 8), and the order of laminating the coating material was reversed (the outermost surface resin film was the lowermost side) in the same manner as in Example 1, A solar cell module was produced. The aluminum plate shown in FIG. 8 is a sheet for forming irregularities, and has an advantage that it can be used semipermanently unlike the sheet in the first embodiment. Such irregularities formed on the surface of the solar cell module by the aluminum plate can be the same as those formed by using the sheet in Example 1.

[0052]

Example 4 A solar cell module was prepared in the same manner as in Example 1 except that the ETFE film was replaced with an acrylic resin film (Mitsubishi Rayon Co., Ltd., trade name: acryprene, thickness 50 μm).

[0053]

Example 5 In Example 1, corona discharge treatment was performed on both sides of the ETFE film (wetting index 40 dyne).
A solar cell module was produced in the same manner as in Example 1 except for the above.

[0054]

Comparative Example 1 A solar cell module was produced in the same manner as in Example 1 except that the sheet for forming the unevenness in Example 1 was changed to a 16 × 16 mesh stainless mesh (wire diameter: 0.25 mm).

[0055]

[Comparative Example 2] A solar cell module was produced in the same manner as in Example 1 except that the 40 x 40 mesh stainless mesh (wire diameter 0.15 mm) was used as the sheet for forming irregularities in Example 1. .

[0056]

[Comparative Example 3] A sheet for forming irregularities in Example 1 was made of an organic fiber non-woven fabric having a mesh-like embossed surface (manufactured by Asahi Kasei, trade name: ELTAS, product number E05).
A solar cell module was produced in the same manner as in Example 1 except that (030) was used.

[0057]

Comparative Example 4 A solar cell module was produced in the same manner as in Example 1 except that the sheet for forming the unevenness was not used in Example 1 and the surface was made smooth.

[0058]

Comparative Example 5 Example 3 except that the stretched ETFE film thickness was changed to 38 μm for the surface resin film in Example 3.
A solar cell module was produced in the same manner as in.

[0059]

[Evaluation] Examples 1 to 5 and Comparative Examples 1 to 5
The following items were evaluated for each of the solar cell modules obtained in 1. The evaluation results obtained are summarized in Table 1.

(1) Initial appearance The initial appearance of the solar cell module was visually observed for the presence or absence of surface wrinkles, breaks (cracks), and the conspicuous color unevenness of the semiconductor film. The evaluation results are shown in Table 1 according to the following evaluation criteria. That is, ◯: when there is no appearance defect, Δ: when there is some appearance defect but it is acceptable for practical use, x: when wrinkles, tears and color unevenness are remarkable and the appearance defect is very large.

(2) Outdoor exposure test The solar cell module was installed outdoors (on the outdoor exposure inside the Ecology Research Institute, Kizugawadai Canon Co., Ltd., Kizu-cho, Soraku-gun, Kyoto) and evaluated 12 months and 24 months later. It was On the 12th and 24th months of outdoor exposure, the following two days were set as the measurement dates. That is, one of the days in which fine weather (day without rain) continued for one week or more consecutively, and the day after the day of rainfall after the measurement day.
The evaluation was performed on the appearance, stains and recovery as described below. Appearance: Appearance On the measurement day, the surface coating material was visually observed for defects such as wrinkles and surface film tears (cracks). Regarding the results of visual observation on the appearance, the results are shown in Table 1 on the basis of: very good: ○, slightly defective but not practically acceptable: Δ, and significant appearance defect: X . Contamination: On the measurement day, how the surface film was contaminated was visually observed and the total light transmittance was measured, and the initial decrease in the total light transmittance (500 nm) was defined as the dirt ratio. The evaluation results are as follows: ○: less than 7%, △: decrease in total light transmittance.
The results are shown in Table 1 on the basis of 7% or more and less than 15% and x: 15% or more. Recovery: On the measurement day, how the surface film was soiled was measured by total light transmittance, and (Measurement day)-(Measured measurement value) = Recovery rate (500 nm). The evaluation results are shown in Table 1 on the basis of a recovery rate of ◯: 0.5% or more, Δ: 0.2% or more and less than 0.5%, and ×: 0.2% or less.

(3) Scratch resistance By the method as shown in FIG. 6, the most uneven portion of the module surface on the metal member is scratched with a weight of 2 pounds and 5 pounds, and the surface coating material after scratching is external. It was evaluated whether or not the insulation property with respect to can be maintained. The judgment is
The module was immersed in an electrolyte solution having a conductivity of 3000 Ω · cm, and a case where the leakage current exceeded 50 μA when a voltage of 2200 V was applied between the device and the solution was regarded as a failure. The evaluation result is 5 pounds passed: ○, 2 pounds passed:
△, 2 lbs rejected: Shown in Table 1 on the basis of ×.

(4) Temperature and Humidity Cycle Test The solar cell module was tested at −40 ° C./0.5 hours: 85 ° C.
After repeating the temperature / humidity cycle test of / 85% (relative humidity) / 4 hours 20 times, the appearance of the solar cell module was visually observed. The results are as follows: ○: No change in appearance, △: Some appearance defects but not problematic for practical use, ×: Defects such as poor deaeration, module bending, and wrinkles are very large. It is shown in Table 1 on the basis of the case.

As is clear from Table 1, the solar cell modules of the examples all had a practically sufficient initial appearance and scratch resistance. Further, even after 12 months and 24 months of outdoor exposure, the surface coating material was good, with no wrinkles or cracks in the surface film. In addition, there was nothing particularly terrible in terms of how dirt was accumulated, and the appearance was completely inconspicuous. There is no significant decrease in total light transmittance of 15% or more,
Furthermore, after the rain, the dirt is removed along the groove provided on the surface and is recovered. It is possible to manufacture a highly reliable module that does not reduce the efficiency of the solar cell module even in actual use. The appearance after the temperature / humidity cycle test was also good without any problems.

On the other hand, in Comparative Example 1 in which the aluminum mesh of 16 × 18 mesh is used as the sheet for forming the surface irregularities, the irregularities in the semiconductor film are noticeable in the initial appearance due to the deep and regular lattice irregularities. . Also, after outdoor exposure, dirt adhering to the surface easily accumulates in the recesses,
Since no recovery due to rainfall was observed, a considerable amount of dirt was observed on the appearance. Moreover, since the recesses are deep, sufficient results were not obtained in terms of scratch resistance. further,
After the temperature / humidity cycle test, there was a defect that the surface film and the filler were peeled off at the bottom of the recess. Further, in Comparative Example 2 in which a 40 × 40 mesh aluminum mesh was used as a sheet for forming unevenness on the surface, stains were easily removed as compared with Comparative Example 1, but conversely, the surface coating material during outdoor exposure was used. It was difficult to suppress the generation of wrinkles due to the expansion and contraction, and some defects were observed. Also, in the initial appearance, it was difficult to absorb wrinkles during production, and some defects were seen. However, these are practically acceptable.

In Comparative Example 3 in which a mesh-like embossed organic non-woven fabric was used as a sheet for forming irregularities on the surface, the height of the irregularities was lower than that formed by the mesh, so the degree of contamination Is slightly reduced, but 2
After four months, the dirt buildup had worsened. Also,
The disadvantages due to the shallow unevenness are that fingerprints and the like are likely to be attached to the external appearance so that they are easily noticeable, and the irregularities of the semiconductor film are easily formed because the irregularities are regularly formed. Further, in Comparative Example 4 in which the solar cell module had a smooth surface, wrinkles were likely to occur during production, and the yield decreased. In addition, wrinkles were generated on the surface during outdoor exposure and temperature / humidity cycle tests. In Comparative Example 5 in which the stretched ETFE film was used as the surface resin film, a crack was generated in the bottom of the recess, and the resin film and the filler were separated at the bottom. Even for dirt, because stretched ETFE is used for the surface film,
It becomes a harder film than the unstretched one, and is easily scratched during exposure and stains are likely to accumulate.

[0067]

[Table 1]

[0068]

According to the present invention, the surface of the photovoltaic element on the light incident side is a transparent organic polymer resin layer and at least two transparent surface protective film layers in contact with the transparent organic polymer resin layer.
In a solar cell module coated with a coating material of more than one layer, irregularities are provided on the surface of the coating material, and the pitch of three adjacent irregularities selected arbitrarily among them (the apex of the concave portion or the distance between the apex of the convex portion) is set. 20 μm <| X _n −X _{n + 2} | <5, _where X _n , X _{n + 1} and X _{n + 2} , respectively.
00 μm and X _{n + 2} / X _n <0.9 or X _{n + 2}
With / X _n> 1.1, less direct reflection light of the surface, hardly wrinkles in the surface film, even when long-term outdoor use, dirt hardly adhere easily fall, a highly reliable solar cell module Can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view and cross-sectional view of a solar cell module of the present invention.

FIG. 2 is a schematic cross-sectional view showing the basic structure of a photovoltaic element used in the solar cell module shown in FIG.

FIG. 3 is a stacking diagram during production of the solar cell module according to the present invention.

FIG. 4 is a cross-sectional view of a serialized module according to the present invention.

FIG. 5 is a schematic sectional view of a solar cell module according to the present invention.

FIG. 6 is a schematic diagram showing a scratch resistance test.

FIG. 7 is a schematic cross-sectional view showing an example of a conventional solar cell module.

FIG. 8 is an aluminum plate in which unevenness is formed in advance in order to form unevenness in the present invention.

[Explanation of symbols]

101, 301, 401, 501, 701 Photovoltaic element 102 Transparent organic polymer resin impregnated with fibrous inorganic compound 103, 304, 504, 703 Surface resin film 104 Backside filler 105, 505, 704 Insulation film 106 Surface coating Material irregularities 201 Conductive substrate 202 Backside reflective layer 203 Semiconductor photoactive layer 204 Transparent conductive layer 205,405a Current collecting electrode (plus side) 405b Current collecting electrode (minus side) 206a Output terminal (plus side terminal) 206b Output terminal ( Minus side terminal) 207,408 Solder 208,407 Insulation tape 302,502 Fibrous inorganic compound 303,503,702 Transparent organic polymer resin 306 Copper tab 506 Reinforcement plate 507 Release film 508 For forming irregularities on the surface Sheet 601 solar cell module The convex portion of the aluminum plate corresponding to the grooves of the surface 602 blade 801 aluminum plate 802 module

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ichiro Kataoka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Satoshi Yamada 3- 30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside the corporation

Claims (17)

[Claims] 1. A surface of a photovoltaic element on the light incident side is covered with at least two transparent organic polymer resin layers and at least two transparent surface protective film layers on the outermost surface in contact therewith. In the solar cell module, the surface of the coating material has a plurality of irregularities, and the irregularities each have a pitch of three adjacent irregularities arbitrarily selected (the apex of the concave portion or the distance between the apices of the convex portions). _{If n} , X _{n + 1} and X _{n + 2} , then 20 μm <| X _n −X _{n + 2} | <50
0 μm and X _{n + 2} / X _n <0.9 or X _{n + 2} /
A solar cell module, wherein X _n > 1.1. 2. The solar cell module according to claim 1, wherein the pitch of the unevenness provided on the surface of the coating material is 50 μm to 500 μm. 3. The heights of three adjacent irregularities selected arbitrarily among the irregularities provided on the surface of the coating material (height difference between adjacent convex portions of concave portions) are Y _n , Y _{n + 1} and Y. _{When n + 2} , 10 μm <| Y _n −Y _{n + 2} | <200 μm, and Y _n / Y _{n + 2} <0.9 or Y _n / Y _{n + 2} > 1.1.
The solar cell module according to claim 1 or 2, wherein 4. The solar cell module according to claim 1, wherein the unevenness provided on the surface of the coating material has a height of 10 μm to 300 μm. 5. The solar cell module according to claim 1, wherein the unevenness is formed by overlapping lines having a groove length of 50 mm or more formed by the unevenness. . 6. The solar cell module according to claim 1, wherein the groove formed by the concavities and convexities crosses the surface of the solar cell module from end to end. 7. The diameter of the wire forming the unevenness is 0.1 m
It is m to 3 mm, The solar cell module in any one of Claim 1 to 6 characterized by the above-mentioned. 8. The solar cell module according to claim 1, wherein the transparent protective film layer is made of a fluoride polymer. 9. The solar cell module according to claim 8, wherein the fluoride polymer is a tetrafluoroethylene-ethylene copolymer. 10. The solar cell module according to claim 9, wherein the wetting index on the photovoltaic element side of the film layer made of the tetrafluoroethylene-ethylene copolymer is 40 dyne to 45 dyne. 11. The ASTM of the transparent protective film layer
The solar cell module according to any one of claims 1 to 10, wherein the tensile breaking elongation in the D-882 test method is 200% to 800% in both the longitudinal direction and the lateral direction. 12. The solar cell module according to claim 1, wherein the transparent organic polymer resin layer is made of a thermoplastic polyolefin resin. 13. The solar cell module according to claim 12, wherein the thermoplastic polyolefin resin is an ethylene-vinyl acetate copolymer (EVA). 14. The transparent organic polymer resin layer is treated with a coupling agent, according to any one of claims 1 to 1.
3. The solar cell module according to any one of 3. 15. The transparent organic polymer resin layer contains a fibrous inorganic compound.
4. The solar cell module according to any one of 4. 16. The solar cell module according to claim 15, wherein the fibrous inorganic compound is treated with a coupling agent. 17. The solar cell module according to claim 15, wherein the fibrous inorganic compound is a glass fiber non-woven fabric.