JPH0818086A - Solar cell module - Google Patents

Abstract

PURPOSE:To obtain a solar cell module which has excellent weather resistance, heat insulation and impact resistance and can suppress long period performance deterioration of a photovoltaic element to a minimum limit by providing a semiconductor active layer as a light-transforming member, and providing a transparent surface covering material containing alkylated tertiary amine on a light incident side surface. CONSTITUTION:A solar cell module is formed of a board 101, a photovoltaic element 102, a rear surface coating film 103, a rear surface filler 104, a filler 105 having surface transparency and a transparent film 106 disposed on the uppermost surface. The element 102 is obtained by forming a semiconductor photoactive element as a light-transforming member on a conductive base. As the filler 105 having surface transparency, ethylene copolymer is preferable, and crosslinking is preferable by considering high-temperature available environment. Since the copolymer has deteriorated light resistance, it is preferable to add light stabilizer. As the stabilizer, alkylated tertiary amine is necessarily contained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell module, and more particularly to a solar cell module whose incident light side is resin-coated.

[0002]

2. Description of the Related Art In recent years, awareness of environmental problems has been increasing worldwide. Above all, there is a great sense of concern about the global warming phenomenon caused by CO ₂ emission, and the desire for clean energy by a generator that does not use fossil fuel is increasing more and more. At present, solar cells, which are photoelectric conversion elements, are safe and easy to handle.
It can be said that it is a promising clean energy source.

There are various forms of such solar cells. (1) Crystalline silicon solar cell (2) Polycrystalline silicon solar cell (3) Amorphous silicon solar cell (including microcrystals here) (4) Copper indium serenade solar cell (5) ) Compound semiconductor solar cells. Among them, polycrystalline 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 have recently been actively pursued in various fields.

Further, among these solar cells, a typical example is an amorphous silicon solar cell in which silicon is deposited on a conductive metal substrate, which is a substrate having a conductive surface, and a transparent conductive layer is formed thereon. The thin-film solar cell is lightweight, and has high impact resistance and flexibility, and thus is expected as a future module form. However, unlike the case of depositing silicon on a glass substrate, it is necessary to protect the solar cell by covering the light incident side surface with a transparent coating material. As the outermost surface of this surface covering material, transparent fluororesin such as glass or fluororesin film or fluororesin paint is used, and various thermoplastic transparent organic resins are considered as fillers inside thereof. The reason why the glass substrate is used for the outermost layer is that it has excellent weather resistance and can reduce the decrease in conversion efficiency of the solar cell module due to the decrease in light transmittance due to deterioration.

On the other hand, the reason why the fluorine-based resin is used for the outermost surface is that it is excellent in weather resistance and water repellency, and can reduce the decrease in conversion efficiency of the solar cell module due to the decrease in light transmittance due to deterioration and dirt. Is. Furthermore,
This is because the solar cell module can be easily sealed by the heat treatment. It is inexpensive to use various thermoplastic transparent resins for the filler, and it can be used in a large amount to protect the internal photovoltaic element.

FIG. 4 shows an example of such a solar cell module. In FIG. 4, 401 is a fluorine resin film, 402 is a thermoplastic transparent organic resin, 403 is a photovoltaic element, and 404 is an insulator layer. In this example, the same organic resin as the light receiving surface is also used on the back surface. More specifically, the fluororesin 401 includes ETFE (ethylene-
Tetrafluoroethylene copolymer) film, PVF
There is a (polyvinyl fluoride) film, and the thermoplastic transparent organic resin 402 includes EVA (ethylene-vinyl acetate copolymer) and butyral resin. Further, various organic resin films such as a nylon film and an aluminum laminated Tedlar film are used for the insulating layer 404. In this example, the thermoplastic transparent organic resin 402 functions as an adhesive with the photovoltaic element 403, the fluorine-based resin film 401, and the insulating layer 404 if they are in contact with each other. On the other hand, it also serves as a filler that protects the solar cell from external scratches and impacts.

However, when exposed to a natural environment for a period of 20 years or more, it is the actual situation that a material having both weather resistance and impact resistance is not yet known in the above surface coating composition. Specifically, when a glass substrate is used as the surface layer, the glass substrate is easily damaged by falling hail or pebbles, and the protection of the light conversion member is impaired.

On the other hand, when the fluorine-based resin is used as the outermost layer, various resin stabilizers added to the coating material are decomposed by ultraviolet rays, moisture or heat during 20 years of long-term outdoor exposure. It is known that it is volatilized, dissolved or dissipated by heat or water. Therefore, the weather resistance cannot be expected due to the coating material in which the resin stabilizer is reduced. That is, it is generally known that resins are colored by ultraviolet rays, ozone, nitrogen oxides or heat. In particular, when a non-single-crystal semiconductor is used, in the case of serially laminating two or more semiconductor photoactive layers that are preferably used in an amorphous silicon system, the coloring of the surface coating material greatly affects the decrease in conversion efficiency. . In other words, since the light conversion members that are stacked in series generate the split wavelengths of sunlight in each semiconductor photoactive layer, if light on the short wavelength side is absorbed by the surface coating material, short wavelength The current generated in the absorbed semiconductor photoactive layer is reduced, and the currents in the other semiconductor photoactive layers also cause current rate limiting. Therefore, the conversion efficiency of the light conversion member as a whole is significantly reduced.

When the surface layer is a fluororesin, the volatilization of the resin stabilizer becomes significantly larger than that of glass,
The decrease in conversion efficiency becomes more remarkable. As these resin stabilizers, JPL (US Jet Propulsion Research Institute) U.
S. Department of Energy Investigation of test metho
ds, material properties, and processes for solarce
ll encapsulants Annual Report, June, 1979 ", EV
It is known that a secondary amine light stabilizer is preferably used for A. Specifically, it is bis (2,2,6,6-tetramethyl-4-piperidyl) sepacate. However, not only the light resistance but also the heat resistance of the secondary amine light stabilizer is insufficiently improved.

The above problem becomes more remarkable in the case of a solar cell module having no cooling means or a building material-integrated type application such as a roof material having a higher module temperature. That is, when the module temperature is 80 ° C. or higher, the coloring of the surface coating material is further promoted. In addition, in the production of solar cell modules, the heating and bonding step is generally performed at 130 ° C.
It takes about 20 to 100 minutes at 160 ° C.

The conditions for such heat-bonding are determined not only by filling and bonding the respective members, but also by the progress of crosslinking of resin such as EVA as a filler. Although it is sufficient to raise the temperature in order to process this step in a short time, the module after heat bonding is slightly colored, which causes a problem that the initial conversion efficiency is lowered.

As a method for improving these problems, it can be considered to lower the decomposition temperature of the crosslinking agent added to the filler resin, specifically, the organic peroxide. That is, the temperature at which radicals are generated is changed to an organic peroxide which is lower by about 20 ° C. However, if the filler of this low temperature crosslinking agent is used, the yellowing of the resin after heat bonding can be prevented, but since the bonding temperature of each member is low or short, the bonding strength between each member and the filler is not sufficient. There is a problem that there is no.

A roof solar cell module whose appearance is particularly important is designed to use a colored steel plate as a reinforcing plate. For this color steel sheet, a silicone-based leveling agent is preferably used for the purpose of preventing pinholes during coating and preventing stains. Adhesiveness cannot be expected for a steel sheet having such a coating unless radicals are extracted by the organic peroxide. Although the low-temperature cross-linking filler also generates radicals, the temperature of the member is low and covalent bonds due to radical extraction are not sufficient.
Therefore, there is a problem that the adhesiveness is low as compared with the one that is heat-bonded at a high temperature.

[0014]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is excellent in weather resistance and heat resistance, minimizes long-term performance deterioration of a photovoltaic element, and further, An object of the present invention is to provide a surface coating material for a solar cell module which is less likely to be damaged by impact.

[0015]

As a result of intensive research and development for solving the above problems, the present inventor has found that the following surface coating materials for solar cell modules are the best. That is, in a solar cell module including at least two layers of a photovoltaic element and a transparent surface coating material provided on the light incident side surface, the surface coating material has an alkylated tertiary amine. It is a solar cell module characterized in that.

[0016]

The present invention provides a solar cell module comprising at least two layers of a semiconductor photoactive layer as a light conversion member and a transparent surface coating material provided on the light incident side surface, wherein the surface coating material is A solar cell module comprising a light stabilizer having an alkylated tertiary amine. According to this solar cell module, the following effects can be expected.

It is possible to obtain a solar cell module in which conversion efficiency is less likely to decrease even after long-term use. By using a fluororesin film as the surface layer, a solar cell module that is strong against external impact can be obtained. Furthermore, an inexpensive solar cell module can be manufactured by using an ethylene copolymer resin as a filler.

By limiting the chemical structure of the filler to a copolymer resin of unsaturated fatty acid ester, a solar cell module having excellent moisture resistance can be obtained. On the other hand, a module using a material containing an inorganic ultraviolet absorber as the surface coating material is a solar cell module having excellent weather resistance, particularly light resistance. Alternatively, a solar cell module having excellent light resistance can be obtained by using a high molecular weight ultraviolet absorber instead of the inorganic ultraviolet absorber.

[0019]

Examples of the Embodiments As a result of various experiments, the present inventor found an alkylated tertiary amine as a light stabilizer contained in a resin-coated solar cell module. Less than,
The present invention will be described in detail.

(Module) FIG. 1 shows a schematic configuration diagram of the solar cell module of the present invention. In FIG. 1, when light is incident from above, 101 is a substrate, 102 is a photovoltaic element, 103 is a backside coating film, and 104 is a backside filler. Reference numeral 105 denotes a light-transmitting filler on the surface, 10
Reference numeral 6 is a translucent film located on the outermost surface.

Light from the outside is exposed to the outermost film 106.
The incident electromotive force enters the photovoltaic element 102, reaches the photovoltaic element 102, and the generated electromotive force is taken out from an output terminal (not shown). Similarly, when light is incident from below through the substrate 101 made of a transparent resin or the like, the filler 104 and the back surface coating film below have a light-transmitting property.

The photovoltaic element 102 according to the present invention is one in which a semiconductor photoactive layer as a light converting member is formed on at least a conductive substrate. A schematic configuration diagram as an example thereof is shown in FIG. In this figure, 201 is a conductive substrate, 202 is a back reflection layer, 203 is a semiconductor photoactive layer, 2
Reference numeral 04 is a transparent conductive layer, and 205 is a collector electrode.

Conductive Substrate 201 The conductive substrate 201 serves as a substrate for the photovoltaic element and at the same time serves as a lower electrode. Examples of the material include silicon, tantalum, molybdenum, tungsten, stainless steel, aluminum, copper, titanium, carbon sheet, lead-plated steel plate, resin film having a conductive layer formed thereon, and ceramic glass.

The back surface reflection layer 2 is formed on the conductive substrate 201.
As 02, a metal layer, a metal oxide layer, or a stack of a plurality of metal layers and metal oxide layers may be formed.
For the metal layer, for example, Ti, Cr, Mo, W, Al, A
g, Ni, Cu, etc. are used, and the metal oxide layer is
For example, ZnO, TiO ₂ , SnO ₂ , ITO or the like is used. As a method of forming the metal layer and the metal oxide layer, there are a resistance heating vapor deposition method, an electron beam vapor deposition method, a sputtering method and the like.

Semiconductor Photoactive Layer 203 The semiconductor photoactive layer 203 is a portion for performing photoelectric conversion. Specific materials are pn junction type polycrystalline silicon, pin junction type amorphous silicon, CuInSe ₂ ,
CuInS ₂ , GaAs, CdS / Cu ₂ S, CdS / C
Examples thereof include compound semiconductors such as dTe, CdS / InP, CdTe / Cu ₂ Te and the like.

As a method of forming the semiconductor photoactive layer,
Sheets of molten silicon or heat treatment of amorphous silicon in the case of polycrystalline silicon, plasma CVD method using silane gas as a raw material in the case of amorphous silicon, ion plating method, ion beam deposition method in the case of compound semiconductor, There are a vacuum vapor deposition method, a sputtering method, an electrodeposition method and the like.

Transparent Conductive Layer 204 The transparent conductive layer 204 serves as the upper electrode of the solar cell. Examples of the material used include In ₂ O ₃ and Sn
O ₂ , In ₂ O ₃ —SnO ₂ (ITO), ZnO, Ti
There is a crystalline semiconductor layer doped with O ₂ and Cd ₂ SnO ₄ high concentration impurities. Examples of the forming method include resistance heating vapor deposition, sputtering method, spray method, CVD method, and impurity diffusion method.

Collector electrode 205 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 collector electrode 205, for example, T
Examples thereof include i, Cr, Mo, W, Al, Ag, Ni, Cu, Sn, alloys thereof, and conductive paste such as silver paste.

As a method of forming the collecting electrode 205, a sputtering method using a mask pattern, a resistance heating method, C
VD method, a method of depositing a metal film on the entire surface and then removing unnecessary portions by etching, and patterning, optical CVD
There is a method of directly forming a grid electrode pattern by, a method of plating after forming a mask of a negative pattern of the grid electrode pattern, a method of printing a conductive paste, a method of sticking a metal wire, and the like. 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.

Output Terminal 206 Finally, in order to take out electromotive force, the output terminal 206 is attached to the conductive substrate and the collecting electrode. A method of spot welding or soldering a metal body such as a copper tab to the conductive substrate is used, and a method of electrically connecting the metal body to the collector electrode with a conductive paste or solder is used.

The photovoltaic elements produced by the above method are connected in series or in parallel according to the desired voltage or current. Further, a photovoltaic element can be integrated on an insulated substrate to obtain a desired voltage or current.

Cover film 103 on the back surface The cover film 103 on the back surface maintains electrical insulation between the conductive substrate 101 of the photovoltaic element and the outside.
As a material, a material which can ensure sufficient electric insulation with a conductive substrate, has excellent long-term durability, and can withstand thermal expansion and thermal contraction and which is also flexible is preferable. Examples of the film that is preferably used include nylon and polyethylene terephthalate.

Filler 104 on Back Side Filler 104 on the back side is for bonding the substrate 101 and the covering film 103 on the back side. As a material, a material which is capable of ensuring sufficient adhesiveness to a conductive substrate, has excellent long-term durability, and can withstand thermal expansion and thermal contraction, and which is also flexible, is preferable. Materials that are preferably used include hot-melt materials such as EVA and polyvinyl butyral, double-sided tapes, and flexible epoxy adhesives.

When the solar cell module is used at a high temperature, for example, in a building material integrated type such as a roofing material, it is more preferable to crosslink in order to ensure adhesion at a high temperature.
As a crosslinking method such as EVA, a method using an organic peroxide is generally used.

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 prevent distortion and warpage due to temperature change. For example, steel plate, plastic plate, FRP
A (glass fiber reinforced plastic) plate is preferred.

Filler 105 Next, the filler 105 used in the present invention will be described in detail below. The filler is necessary to cover the irregularities of the photovoltaic element with resin and to secure the adhesion with the surface film. Therefore, weather resistance, adhesiveness, and heat resistance are required. The filler is not particularly limited as long as it satisfies these requirements, but an ethylene-based copolymer is particularly preferable as the filler. Generally, ethylene copolymers are excellent in heat resistance and adhesiveness and are inexpensive. For the above reason, EVA (ethylene-vinyl acetate copolymer) has been favorably used in the past.

However, EVA has a high hygroscopicity, and a module using a glass substrate on the surface or a crystalline silicon semiconductor having substantially no shunt has little influence of the hygroscopicity, but the surface layer is made of a resin film. A filler having low hygroscopicity is more preferable for a module having excellent impact resistance or a semiconductor having a shunt such as an amorphous silicon type.

As the filler having a low hygroscopicity, examples of the unsaturated fatty acid ester copolymer resin include EEA (ethylene-ethyl acrylate) and EMA (ethylene-methyl acrylate). Flexibility is obtained with a lower copolymerization ratio than EVA. That is, the content of the ester, which is a functional group that easily absorbs moisture, is small, and flexibility can be exhibited.

Specifically, EVA is 33% vinyl acetate.
The copolymerized resin and the resin obtained by copolymerizing 25% of ethylene-ethyl acrylate with EEA have almost the same mechanical properties, and EEA is superior at a low embrittlement temperature. The form of the filler before heat-bonding is preferably a film. Examples of the method for molding the above material into a film include an inflation method and an extrusion method by a T-die method.

(Crosslinking Agent) It is preferable to crosslink the filler in consideration of a high temperature use environment. For crosslinking, a method of adding isocyanate, melamine, or organic peroxide to the filler can be mentioned. In a system in which an isocyanate is used in combination, it is preferable to use a blocking agent because the reaction may proceed during the extrusion process.

The isocyanate used in the present invention is preferably an aliphatic or aromatic compound added with water.
Examples thereof include hexamethylene diisocyanate, isophorone diisocyanate, and water-added methylene diphenyl diisocyanate. In addition, examples of the melamine used in the present invention include hexakismethylmelamine.

Further, as the isocyanate blocking agent, epsilon caprolactam, methyl ethyl ketone oxime,
Alcohols such as ethyl acetoacetate, phenol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and tert-butanol are preferable. In the step of extruding, there is no elimination of the blocking agent, and in the case of crosslinking, it is necessary that the block be eliminated and react with the hydroxyl group in the filler. As the high temperature dissociation type blocking agent, the above-mentioned epsilon caplactam is preferably used.

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. Known methods of activating organic peroxides include thermal decomposition, redox decomposition, and ionic decomposition. Generally, the thermal decomposition method is preferred. Specific examples of the chemical structure of organic peroxides are roughly classified into hydroperoxides, dialkyl (allyl) peroxides, diacyl peroxides, peroxyketals, peroxyesters, peroxycarbonates and ketone peroxides.

Hydroperoxides 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.

Examples of the dialkyl (allyl) peroxide type include di-t-butyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide and the like. As the diacyl peroxide type, diacetyl peroxide,
Dipropionyl peroxide, diisobutyryl peroxide, dioctanoyl peroxide, didecanoyl peroxide, dilauroyl peroxide, bis (3,3,3,3
5-trimethylhexanoyl) peroxide, benzoyl peroxide, m-toluyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and peroxysuccinic acid.

As the peroxyketal system, 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 the like.

As the peroxy ester type, t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxypivalate, t-butyl peroxy neodecanoate, t-butyl peroxy 3,3,5-trimethyl. Hexanoate, t-butylperoxy 2-ethylhexanoate, (1,1,3,3
-Tetramethylbutylperoxy) 2-ethylhexanoate, t-butylperoxylaurate, t-butylperoxybenzoate, di (t-butylperoxy)
Adipate, 2,5-dimethyl 2,5-di (peroxy 2-ethylhexanoyl) hexane, di (t-butylperoxy) isophthalate, t-butylperoxymalate, acetylcyclohexylsulfonyl peroxide and the like.

As the peroxycarbonate system, t-
Butyl peroxyisopropyl carbonate, di-n-
Propylperoxydicarbonate, di-sec-butylperoxydicarbonate, di (isopropylperoxy) dicarbonate, di (2-ethylhexylperoxy) dicarbonate, di (2-ethoxyethylperoxy) dicarbonate, di (methoxyisopropylperoxy) carbonate, Examples thereof include di (3-methoxybutylperoxy) dicarbonate and bis- (4-t-butylcyclohexylperoxy) dicarbonate.

Examples of ketone peroxides include acetylacetone peroxide, methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, and ketone peroxide. For other structures, vinyltris (t-butylperoxy) silane and the like are also known.

The amount of the organic peroxide added is 0.5 to 5 parts by weight with respect to 100 parts by weight of the filler resin. The heat bonding condition can be determined by the temperature at which radicals of the organic peroxide of the present invention are generated and the bonding strength with each member.

In general, it is desirable that the organic peroxide is decomposed to 1/4 or less of the initial organic peroxide. That is, when the half-life of an organic peroxide at a certain temperature is known, it is desirable that the half-life at that temperature is twice or more. However, E
It is preferable to apply a temperature of 90 ° C. or more and 180 ° C. or less for 10 minutes or more to the filling property of VA. It is more preferably 110 ° C. or higher and 160 ° C. or lower. If it is lower than the lower limit, the decomposition of organic peroxide is insufficient, and E
Remarkably low VA cross-linking. When EVA is not sufficiently crosslinked, EVA flows at high temperature and wrinkles throughout the coating material.
This wrinkle does not return to a wrinkle-free state even when it is cooled, resulting in a poor appearance. Alternatively, if the module is installed with an inclination, creep (EV
A shifts). If the temperature is higher than the above upper limit,
EVA, which is the filler, turns yellow, and the initial conversion efficiency of the module is significantly reduced.

(Electron beam curing) It is preferable to add the above-mentioned cross-linking agent to the filler film, heat it at a high temperature and complete the cross-linking, and then heat-bond it to the photovoltaic element. Alternatively, the filler film may be cross-linked by irradiating it with radiation. Generally, radiation is an electron beam,
Although there are gamma rays, electron beams are preferred for industrial use.

Electron beam irradiation devices are roughly classified into scanning type and non-scanning type. 300 KeV or higher for scanning type, 300 for non-scanning type
Suitable for accelerating voltage of KeV or less. When the thickness of the filler film is 500 μm or more, the acceleration voltage is 300 Ke
It is preferably V or more.

The dose varies depending on the material used for the filling material, but is preferably about 1 to 100 Mrad. 10
At doses higher than 0 Mrad, the filler will turn yellow, and heat will cause thermal decomposition. In order to carry out electron beam crosslinking more efficiently, it is known to use a crosslinking auxiliary together. Examples include triallyl isocyanuric acid.

Lastly, the outermost transparent re-surface film 106 of the present invention will be described in detail below.

(Silane Coupling Agent) By using a silane coupling agent in addition to the crosslinking agent in the filler film, it is possible to improve the adhesion to the surface of the photovoltaic element. As the silane coupling agent, vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-ethoxycyclohexyl) ethyl. Trimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-
Aminopropyltriethoxysilane, N-phenyl-γ
-Aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane and the like can be mentioned.

Alternatively, instead of adding the silane coupling agent in the filler film, there is also a method of coating the above silane coupling agent on the photovoltaic element and drying. In this method, it is effective to wash the excess silane coupling agent on the substrate with water or a solvent. In general, ethylene copolymers are inferior in light resistance to heat resistance,
It is more preferable to add an ultraviolet absorber or a light stabilizer.

(Light Stabilizer) As a light stabilizer used in the solar cell module of the present invention, as a result of various experiments by the present inventors, it is necessary to have an alkylated tertiary amine.

By containing a light stabilizer having an alkylated tertiary amine, the surface coating material is excellent in light resistance and heat resistance. That is, tetra (1, 2,
2,6,6-Pentamethyl-4-piperidyl) butanetetracarbonate, tri (1,2,2,6,6-pentamethyl-4-piperidyl) tridecylbutanetetracarbonate, bis (1,2,2,2) 6,6-pentamethyl-
4-piperidyl) bis (tridecyl) butane tetracarbonate, mono (1,2,2,6,6-pentamethyl-
4-piperidyl) tris (tridecyl) butanetetracarbonate, bis- [tris (1,2,2,6,6-pentamethyl-4-piperidyl) butanetetracarbonate] spiroglycol or (1,2,2,6) , 6-
Pentamethyl-4-piperidyl) methacrylate,
Copolymerizable light stabilizers such as (1,2,2,6,6-pentamethyl-4-piperidyl) acrylate are mentioned.

The amount of the above-mentioned light stabilizer to be used can be appropriately determined, but in general, the amount added is preferably 0.01% to 5% with respect to the filler resin. More preferably 0.05% to 0.
5%.

(Ultraviolet Absorber) Next, the ultraviolet absorber used in the present invention will be described. The ultraviolet absorber used in the solar cell module is for protecting the surface coating material including the filler from ultraviolet rays, but it is preferable that it does not absorb the effective wavelength of the photovoltaic element. The ultraviolet absorber preferably used in the present invention is preferably an inorganic or high molecular weight ultraviolet absorber from the viewpoint of heat resistance and low volatility.

First, examples of the inorganic ultraviolet absorber include titanium oxide, zinc oxide and tin oxide. The particle size is preferably 50 nm or less, which does not hinder the incidence of sunlight.
Zinc oxide is preferable from the viewpoint of absorption spectrum.

On the other hand, as a UV absorber having a high molecular weight, 2-hydroxy-4- (methacryloyloxyethoxy) benzophenone is added to methyl (meth) acrylate,
Examples thereof include a method of copolymerizing with a monomer such as ethylene or ethylene-acrylic ester.

(Surface Film) Finally, the film used for the surface layer will be described. Since the film is located on the surface of the coating material of the solar cell module, it is necessary to ensure long-term reliability in outdoor exposure of the solar cell module, including weather resistance and stain resistance. The material preferably used in the present invention is polytetrafluoroethylene,
Examples thereof include polyvinyl fluoride and polyvinylidene fluoride. From the viewpoint of transparency and adhesiveness, polyvinylidene fluoride can be preferably used. Corona treatment and plasma treatment are preferably performed in order to improve the adhesiveness with the filler.

In order to increase the mechanical strength, there is a method of stretching in addition to the method of increasing the thickness of the surface film. This can be manufactured by applying a high tension while winding the film when it is extruded.

[0066]

EXAMPLES The present invention will be described in detail below based on examples. (Example 1) First, amorphous silicon (a-Si)
A solar cell (photovoltaic device) is produced. Figure 2 shows the manufacturing procedure
Will be explained.

On the washed stainless steel substrate 201, a spa
Al layer (film thickness 5000
Å) and a ZnO layer (film thickness 5000 Å) are sequentially formed. One
By plasma CVD method_FourAnd PH₃And H₂
A-Si layer having n-type conductivity from the mixed gas of
H_FourAnd H₂A-Si layer having i-type conductivity from mixed gas of
The SiH_FourAnd BF₃And H₂P-type microcrystal from mixed gas of
c-Si layer is formed, n-type layer thickness 150Å / i-type layer thickness
4000Å / p-type layer thickness 100Å / n-type layer thickness 100Å
/ I-type layer thickness 800 Å / p-type layer thickness 100 Å
The tandem a-Si photoelectric conversion semiconductor layer 203 is formed.
Was. Next, as the transparent conductive layer 204, In ₂O₃Thin film
Thickness 700Å), O₂In is vaporized by resistance heating in an atmosphere.
Formed by wearing.

Further, a grid electrode 205 for current collection is formed by screen printing of silver paste, and finally a copper tab is attached as a negative side terminal to the stainless steel substrate 201 using stainless solder, and a tin foil tape is used as a positive side terminal. Was attached to the collector electrode with a conductive adhesive to form an output terminal 206, and a photovoltaic element was obtained.

Next, the filler containing the light stabilizer which is a feature of the present invention will be described. EVA (ethylene-vinyl acetate copolymer) 100 parts as a base polymer, organic peroxide (Penwald Co., trade name Lupasol 101) 1.5 parts as a cross-linking agent, antioxidant (Uniroyal Co., Naugard) P) 0.2 part, tetra (1,2,2,6,6-pentamethyl-4-piperidyl) butane tetracarbonate 0.1 part as a light stabilizer, zinc oxide (manufactured by Sumitomo Cement Co., Ltd.) as an ultraviolet absorber. , Ultrafine zinc oxide, trade name ZnO-200), and 0.25 part of γ-methacryltrimethoxysilane as a silane coupling agent were mixed in an extruder (produced by Yuri Roll Co., trade name GPD). An extruded 460 μm EVA film was prepared.

Next, a process of forming a solar cell module by coating the above photovoltaic element will be described with reference to FIG.
Galvalume steel plate (0.3 m
m thickness), EVA (thickness 460 μm) blended as the surface filler as the adhesive 305 on the back surface, the photovoltaic element 304 produced, the glass nonwoven fabric as the reinforcing material 303 (manufactured by Honshu Paper Co., Ltd., trade name Glasper GMC, basis weight) 300 g / m
² ), EVA blended as the surface filler 302 (thickness 460 μm), and an ethylene-tetrafluoroethylene copolymer film (manufactured by DuPont, trade name Tefzel T2, thickness 38 μm, uniaxially stretched film) as the surface layer 301 are sequentially laminated. did. Next, using a vacuum laminator,
Deaeration, pressure bonding, and heating were performed. The vacuum degree at this time is 1 mmH
Below g, heating is at 150 ° C. for 100 minutes. The module was taken out from the sufficiently cooled laminator.

The following items were evaluated for the solar cell module manufactured by the above method. (1) Weather resistance The solar cell module was put into a sunshine weather meter (Shimadzu Xenon Tester XW-150 light-dark method), and an accelerated weather resistance test was performed to measure conversion efficiency after 5000 hours. However, the photodegradation of amorphous silicon (Steblaron-Ski effect) was excluded. Note that the numerical values in Table 1 are the amounts of change in conversion efficiency, which are expressed as a percentage of the conversion efficiency after the test, with reference to the conversion efficiency before the test. − Indicates a decrease and + indicates an increase.

(2) Heat resistance The solar cell module was left in an atmosphere of 150 ° C. for 14 days, and the conversion efficiency was measured.

(3) Humidity resistance test A reverse bias voltage of 1.0 V was applied while the solar cell module was stored in an atmosphere of 85 ° C./85% relative humidity for 10 hours. The shunt resistance was measured. The change amount before and after the test was -50% or more was passed, and less than -50% was rejected.

(4) Adhesive strength EVA and color steel plate (wear resistant color GL, wear resistant black G
The weather resistant surface of L540) was heat-bonded. The size of the material is 25 mm width, the peeling speed is 50 mm / min, and the peeling direction is 180 degree peeling. 250 μm where EVA breaks
Backed by a thick polycarbonate film.

(5) Initial conversion efficiency The conversion efficiency of the module was determined using a light source of AM1.5. The conversion efficiency of Example 1 was 1.00.

(Example 2) Instead of the light stabilizer used in Example 1, bis- [tris (1,2,2,6,6) was used.
6-Pentamethyl-4-piperidyl) butanetetracarbonate] spiroglycol as a light stabilizer
A solar cell module was produced in exactly the same manner except that some parts were used.

(Example 3) In Example 1, a high molecular weight ultraviolet absorber (2-hydroxy-4) was used as the ultraviolet absorber.
-(Methacryloyloxyethoxy) benzophenone and methyl methacrylate salt, copolymerization ratio is 30 parts by weight: 7
A solar cell module was produced in exactly the same manner except that 0.5 part by weight of 0 part by weight and a molecular weight of 350,000 was used.

(Example 4) A solar cell module was prepared in the same manner as in Example 1 except that 0.3 part of 2-hydroxy-4-n-octoxybenzophenone was used as the ultraviolet absorber.

Example 5 A solar cell module was prepared in the same manner as in Example 1 except that EEA (ethyl acrylate content 25 parts) was used as the base polymer instead of EVA.

(Example 6) A solar cell module was prepared in the same manner as in Example 1, except that a portion having a high shunt resistance was selected.

(Comparative Example 1) In Example 1, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (trade name: Tinupin 770, manufactured by Ciba-Geigy) was used as a light stabilizer. 1 part and 2 as a UV absorber
A solar cell module was produced in exactly the same manner except that 0.3 part of hydroxy-4-n-octoxybenzophenone (manufactured by Cyanamid, trade name UV531) was used.

(Comparative Example 2) In Example 1, the light stabilizer was not used and 2-hydroxy-4- was used as the ultraviolet absorber.
n-octoxybenzophenone (manufactured by Cyanamid,
A solar cell module was manufactured in exactly the same manner except that 0.3 part of trade name UV531) was used.

(Comparative Example 3) A solar cell module was prepared in the same manner as in Example 1, except that a portion having a remarkably low shunt resistance was selected.

(Comparative Example 4) A solar cell module was prepared in the same manner as in Example 1, except that a portion having a significantly high shunt resistance was selected.

(Comparative Example 5) In Example 1, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (manufactured by Ciba Geigy, trade name Tinuvin 770) was used as the light stabilizer in 0.1. And 0.3 parts of 2-hydroxy-4-n-octoxybenzophenone (manufactured by Cyanamid, trade name UV531) as an ultraviolet absorber, organic peroxide (manufactured by Penwald Co., trade name Lupasol 101, 1)
A solar cell module was produced in exactly the same manner except that the time half-life 138 ° C.) was changed to t-butylperoxymaleic acid (Atochem Yoshitomi Co., trade name Ruperco PMA, 1 hour half-life 110 ° C.).

Comparative Example 6 A solar cell module was prepared in the same manner as in Comparative Example 5, except that the laminating condition was changed from 150 ° C. for 100 minutes to 122 ° C. for 100 minutes. Table 1 shows the evaluation results of the solar cell modules in the above Examples and Comparative Examples.

[0087]

[Table 1]

As is clear from Table 1, the solar cell module using the surface coating material containing the light stabilizer having a tertiary amine is excellent in weather resistance and heat resistance and can be exposed under severe outdoor conditions. In the temperature cycle test and the temperature / humidity cycle test assuming the use of, no change in appearance was shown. Deterioration in the humidity resistance test is remarkably small, and the adhesive strength is large enough for practical use. Furthermore, it can be seen that the module can be manufactured with high initial conversion efficiency.

Further, it can be seen from Examples 1 and 2 that weather resistance can be improved by using an inorganic ultraviolet absorber in combination. From Example 3, it can be seen that the weather resistance can be improved also by using a high molecular weight ultraviolet absorber together.

From Example 4, it can be seen that weather resistance can be improved by using a surface coating material containing a light stabilizer having a tertiary amine. Third from Example 5
Surface coating material E containing a light stabilizer having a primary amine
It can be seen that the weather resistance can be improved even if EA is used.

The method of coating the surface of the solar cell module according to the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the scope of the invention.

[0092]

INDUSTRIAL APPLICABILITY According to the present invention, a solar cell module using a surface coating material containing a light stabilizer having a tertiary amine has excellent weather resistance and heat resistance, and can be used under severe outdoor conditions. There is no problem even in the temperature cycle test and temperature / humidity cycle test assuming the use of.

[Brief description of drawings]

FIG. 1 is an example of a schematic cross-sectional view of a solar cell module according to the present invention.

FIG. 2 is an example of a schematic sectional view showing a basic configuration of a photovoltaic element used in the solar cell module of FIG.

FIG. 3 is a schematic cross-sectional view of another solar cell module of the present invention.

FIG. 4 is a schematic cross-sectional view showing an example of a solar cell module for comparison.

[Explanation of symbols]

 101 substrate, 102 photovoltaic element, 103 backside coating film, 104 backside filler, 105 transparent front filler, 106 outermost film, 201 conductive substrate, 202 backside reflecting layer, 203 semiconductor photoactive layer , 204 transparent conductive layer, 205 current collecting electrode, 206 output terminal, 301 fluororesin layer, 302 transparent filler on the surface, 303 reinforcing material, 304 photovoltaic element, 305 back adhesive, 306 reinforcing material, 401 fluorine -Based resin film, 402 thermoplastic transparent organic resin layer, 403 photovoltaic element, 404 insulator layer.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Satoshi Yamada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Ayako Komori 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (8)

[Claims] 1. A solar cell module comprising a semiconductor photoactive layer as a light conversion member and at least two layers of a transparent surface coating material provided on a light incident side surface, wherein the surface coating material is alkylated. A solar cell module, which has a modified tertiary amine. 2. A photovoltaic element in which the solar cell module has a semiconductor photoactive layer as a light conversion member and a transparent conductive layer formed on a conductive substrate, and a filler provided on a surface on the light incident side. The solar cell module according to claim 1, wherein the solar cell module is composed of a surface coating material including at least two surface layers located on the surface. 3. The solar cell module according to claim 1, wherein the surface layer is a fluororesin. 4. The solar cell module according to claim 1, wherein the filler is made of an ethylene copolymer resin. 5. The solar cell module according to claim 1, wherein the filler is a copolymer resin of unsaturated fatty acid ester. 6. The solar cell module according to claim 1, wherein the surface coating material contains an inorganic ultraviolet absorber. 7. The solar cell module according to claim 1, wherein the surface coating material contains a high molecular weight ultraviolet absorber. 8. The shunt resistance of the light conversion member is 2,0.
The solar cell module according to claim 1, wherein the range is from 00 to 200,000 Ωcm ² .