JP3135477B2 - Solar cell module - Google Patents

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 having an incident light side coated with a resin.

[0002]

2. Description of the Related Art In recent years, awareness of environmental problems has been increasing worldwide. Above all, there is a serious concern about the global warming phenomenon associated with CO ₂ emission, and the demand for clean energy by generators that do not use fossil fuels 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 promising as a clean energy source.

[0003] There are various types of such solar cells. Typical examples are (1) crystalline silicon solar cell (2) polycrystalline silicon solar cell (3) amorphous silicon-based solar cell (including microcrystal here) (4) copper indium selenade 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 relatively large in area at relatively low cost, and have been actively researched and developed in various fields in recent years.

Further, among these solar cells, 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 is representative. Thin-film solar cells are promising as future module forms because they are lightweight, and have excellent impact resistance and flexibility. However, unlike the case where silicon is deposited on a glass substrate, it is necessary to cover the light incident side surface with a transparent covering material to protect the solar cell. As the outermost surface of the surface coating material, a transparent fluororesin such as glass, a fluororesin film or a fluororesin paint is used, and various thermoplastic transparent organic resins are considered as a filler inside. The reason why the glass substrate is used as the outermost layer is that it has excellent weather resistance and can reduce a decrease in conversion efficiency of the solar cell module due to a decrease in light transmittance due to deterioration.

On the other hand, the reason for using a fluororesin on the outermost surface is that it is rich in weather resistance and water repellency, and can reduce a decrease in conversion efficiency of a solar cell module due to a decrease in light transmittance due to deterioration and contamination. It is. Furthermore,
This is because the solar cell module can be easily sealed by the heat treatment. The use of various thermoplastic transparent resins as the filler is inexpensive and can be used in large quantities to protect the internal photovoltaic elements.

FIG. 4 shows an example of such a solar cell module. In FIG. 4, reference numeral 401 denotes a fluorine-based resin film, 402 denotes a thermoplastic transparent organic resin, 403 denotes a photovoltaic element, and 404 denotes an insulator layer. In this example, the same organic resin as the light receiving surface is also used on the back surface. More specifically, 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. Various organic resin films such as a nylon film and an aluminum laminated Tedlar film are used for the insulator layer 404. In this example, if the thermoplastic transparent organic resin 402 is in contact with the photovoltaic element 403, the fluorine-based resin film 401 and the insulator layer 404, it functions as an adhesive with the insulator layer. On the other hand, it also plays a role of a filler that protects the solar cell from external scratches and impacts.

However, in the case of exposing to a natural environment for a period of more than 20 years, it is a fact that no material capable of achieving both weather resistance and impact resistance has been known in the above-mentioned surface coating material 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 a fluororesin is used as the outermost layer, various resin stabilizers added to the coating material are decomposed by ultraviolet rays, moisture or heat during long-term outdoor exposure for 20 years. It is known that it is volatilized or dissolved and dissipated by heat or water. Therefore, weather resistance cannot be expected due to the coating material having a reduced resin stabilizer. That is, it is known that resin is generally 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 which are preferably used in an amorphous silicon system, coloring of the surface coating material has a large effect on a decrease in conversion efficiency. . In other words, since the light converting members stacked in series generate the divided wavelength of sunlight in each semiconductor photoactive layer, if light on the short wavelength side is absorbed by the surface coating material, the short wavelength The current generated by the absorbing semiconductor photoactive layer decreases, and the currents of the other semiconductor photoactive layers also cause current limiting. Therefore, the conversion efficiency of the light conversion member as a whole is greatly reduced.

When the surface layer is made of a fluororesin, the volatilization of the resin stabilizer becomes remarkably larger than that in the case of glass.
The reduction in conversion efficiency is more pronounced. These resin stabilizers include JPL (US Jet Propulsion Laboratory) U.S.A.
S.Department of Energy Investigation of test metho
ds, material properties, and processes for solarce
ll encapsulants Annual Report, June, 1979 "
It is known that a secondary amine light stabilizer is suitably used for A. Specifically, it is bis (2,2,6,6-tetramethyl-4-piperidyl) separate. However, secondary amine light stabilizers are insufficient in light resistance as well as heat resistance.

[0010] The above problem becomes more serious in the case of a building material integrated type application such as a solar cell module having no cooling means and a roof material having a higher module temperature. That is, when the module temperature reaches 80 ° C. or more, coloring of the surface coating material is further promoted. In the production of a solar cell module, the heating and bonding step is generally performed at a temperature of 130 ° C.
It takes about 20 to 100 minutes at 160 ° C.

The conditions for such heat bonding are determined by the progress of cross-linking of a resin such as EVA as a filler, in addition to filling and bonding each member. In order to perform this process in a short time, the temperature may be increased, but the module after heating and bonding is slightly colored, and a problem arises in that the initial conversion efficiency is reduced.

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

[0013] Solar cell modules for roofs, whose appearance is particularly important, are designed to use colored steel plates as reinforcing plates. In this colored steel sheet, a silicone-based leveling agent is suitably used for the purpose of preventing pinholes and stains when applying paint. A steel sheet having such a coating cannot be expected to have adhesiveness unless radicals are extracted by an organic peroxide. Although radicals are generated even in the low-temperature cross-linking filler, the temperature of the member is low and covalent bonding due to radical extraction is not sufficient.
Therefore, there is a problem that the adhesiveness is low as compared with a product which is heated and bonded at a high temperature.

[0014]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by providing excellent weather resistance and heat resistance, minimizing long-term performance degradation of the photovoltaic element, and further preventing An object of the present invention is to provide a surface coating material for a solar cell module that is not easily damaged by impact.

[0015]

Means for Solving the Problems As a result of intensive research and development for solving the above problems, the present inventor has found that the following surface covering material for a solar cell module is the best. That is, in a solar cell module having a semiconductor photoactive layer as a light conversion member, a transparent covering plate provided on the light incident side surface and a surface covering material including a surface layer, and a reinforcing material, the filler is alkylated. A solar cell module comprising a light stabilizer having a tertiary amine.

[0016]

The present invention relates to a solar cell module having a semiconductor photoactive layer as a light conversion member, a surface covering material including a transparent filling plate and a surface layer provided on a light incident side surface, and a reinforcing material. A solar cell module, characterized in that the material has a light stabilizer having an alkylated tertiary amine. According to this solar cell module, the following effects can be expected.

[0017] A solar cell module in which the conversion efficiency is less reduced even when used for a long time can be obtained. By using a fluororesin-based 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 an unsaturated fatty acid ester copolymer resin, a solar cell module excellent in moisture resistance can be obtained. On the other hand, a module using a material containing an inorganic ultraviolet absorber as a surface coating material is a solar cell module having excellent weather resistance, especially excellent light resistance. Alternatively, a solar cell module excellent in light resistance can be obtained by using a high molecular weight ultraviolet absorber instead of the inorganic ultraviolet absorber.

[0019]

EXAMPLES As a result of various experiments, the present inventors have 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 a solar cell module of the present invention. When light is incident from above in FIG. 1, 101 is a substrate, 102 is a photovoltaic element, 103 is a coating film on the back surface, and 104 is a filler on the back surface. 105 is a filler having a light-transmitting surface, 10
Reference numeral 6 denotes a light-transmitting film located on the outermost surface.

Light from the outside is applied to the outermost film 106.
And 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 a substrate 101 made of a transparent resin or the like, the lower filler 104 and the back surface covering film have a light transmitting property.

The photovoltaic element 102 according to the present invention has a semiconductor photoactive layer as a light conversion member formed at least on a conductive substrate. FIG. 2 shows a schematic configuration diagram as an example. In this figure, 201 is a conductive substrate, 202 is a back reflection layer, 203 is a semiconductor photoactive layer,
04 is a transparent conductive layer and 205 is a current collecting electrode.

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

On the conductive substrate 201, the back reflection layer 2
02 may be formed by stacking a plurality of metal layers, metal oxide layers, or a plurality of metal layers and metal oxide layers.
For example, Ti, Cr, Mo, W, Al, A
g, Ni, Cu, etc. are used.
For example, ZnO, TiO ₂ , SnO ₂ , ITO and the like are used. 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.

Semiconductor Photoactive Layer 203 The semiconductor photoactive layer 203 is a portion that performs photoelectric conversion, and specific materials include pn junction type polycrystalline silicon, pin junction type amorphous silicon, CuInSe ₂ ,
CuInS ₂ , GaAs, CdS / Cu ₂ S, CdS / C
Compound semiconductors such as dTe, CdS / InP, and CdTe / Cu ₂ Te are exemplified.

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

Transparent conductive layer 204 The transparent conductive layer 204 functions as an upper electrode of a solar cell. As a material to be used, for example, In ₂ O ₃ , Sn
O ₂ , In ₂ O ₃ —SnO ₂ (ITO), ZnO, Ti
O ₂ , Cd ₂ SnO ₄ High-concentration impurity-doped crystalline semiconductor layers and the like are available. Examples of the formation method include resistance heating evaporation, sputtering, spraying, CVD, and impurity diffusion.

Collector electrode 205 A grid-like collector electrode 205 (grid) may be provided on the transparent conductive layer in order to efficiently collect current.
As a specific material of the collecting electrode 205, for example, T
i, Cr, Mo, W, Al, Ag, Ni, Cu, Sn and alloys thereof, and conductive pastes such as silver paste.

As a method for forming the collector electrode 205, a sputtering method using a mask pattern, a resistance heating method, C
VD method, method of patterning by removing unnecessary portions by etching after depositing a metal film on the entire surface, photo CVD
A method of forming a grid electrode pattern directly, a method of forming a mask of a negative pattern of the grid electrode pattern and then plating, a method of printing a conductive paste, and a method of attaching a metal wire. As the conductive paste, one obtained by dispersing silver, gold, copper, nickel, carbon, or the like in fine powder form in a binder polymer is usually used. Examples of the binder polymer include resins such as polyester, epoxy, acrylic, alkyd, polyvinyl acetate, rubber, urethane, and phenol.

Output Terminal 206 Finally, the output terminal 206 is attached to the conductive substrate and the collecting electrode in order to extract the electromotive force. A method of joining a metal body such as a copper tab to the conductive base by spot welding or solder is used, and a method of electrically connecting the metal body to the current collecting electrode by a conductive paste or solder is used.

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

Back Cover Film 103 The back cover film 103 maintains electrical insulation between the conductive substrate 101 of the photovoltaic element and the outside.
As the material, a material that can secure sufficient electric insulation with the conductive substrate, has excellent long-term durability, can withstand thermal expansion and thermal contraction, and has flexibility is preferable. Suitable films 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 the material, a material that can secure sufficient adhesion to the conductive substrate, has excellent long-term durability, can withstand thermal expansion and thermal contraction, and has flexibility is preferable. Suitable materials include a hot melt material such as EVA and polyvinyl butyral, a double-sided tape, and a flexible epoxy adhesive.

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

A reinforcing plate may be attached to the outside of the backing film in order to increase the mechanical strength of the solar cell module or to prevent distortion and warping due to a temperature change. For example, steel plate, plastic plate, FRP
(Glass fiber reinforced plastic) plates are preferred.

Filler 105 Next, the filler 105 used in the present invention will be described in detail. The filler is necessary to cover the unevenness of the photovoltaic element with a resin and to ensure adhesion to 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 as the filler, an ethylene copolymer is particularly preferable. Generally, an ethylene copolymer is excellent in heat resistance and adhesiveness, and is inexpensive. It is for the above reasons that EVA (ethylene-vinyl acetate copolymer) has conventionally been favorably used.

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

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

Specifically, vinyl acetate is 33% by EVA.
The copolymerized resin and the resin obtained by copolymerizing EEA with 25% of ethylene-ethyl acrylate 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 a method of forming the above material into a film include a method of extruding the material by an inflation method or 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 an isocyanate, melamine, or an organic peroxide to the filler may be used. In a system using an isocyanate in combination, it is preferable to use a blocking agent because the reaction may proceed during the extrusion process.

As the isocyanate used in the present invention, an isocyanate obtained by adding an aliphatic or aromatic water is preferable.
Examples include hexamethylene diisocyanate, isophorone diisocyanate, and water-added methylene diphenyl diisocyanate. The melamine used in the present invention includes hexakismethylmelamine and the like.

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

In the case of EVA, it is common to crosslink with an organic peroxide. Crosslinking with an organic peroxide is performed by free radicals generated from the organic peroxide extracting hydrogen and halogen atoms in the resin to form a CC bond. Thermal decomposition, redox decomposition and ionic decomposition are known as methods for activating organic peroxides. Generally, the thermal decomposition method is preferred. Specific examples of the chemical structure of the organic peroxide are roughly classified into hydroperoxide, dialkyl (allyl) peroxide, diacyl peroxide, peroxyketal, peroxyester, peroxycarbonate, and ketone peroxide.

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 include di-t-butyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide and the like. As diacyl peroxides, 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.

As peroxyketals, 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.

The peroxyesters include 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.

The peroxycarbonates include t-
Butyl peroxyisopropyl carbonate, di-n-
Propylperoxydicarbonate, di-sec-butylperoxydicarbonate, di (isopropylperoxy) dicarbonate, di (2-ethylhexylperoxy) dicarbonate, di (2-ethoxyethylperoxy) dicarbonate, di (methoxyisopropylperoxy) carbonate, Di (3-methoxybutylperoxy) dicarbonate, bis- (4-t-butylcyclohexylperoxy) dicarbonate and the like can be mentioned.

The ketone peroxides include acetylacetone peroxide, methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, ketone peroxide and the like. In other structures, vinyl tris (t-butylperoxy) silane and the like are also known.

The amount of the organic peroxide is 0.5 to 5 parts by weight based on 100 parts by weight of the filler resin. The heating and bonding conditions 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, if the half-life of the organic peroxide at a certain temperature is known, it is desirable that the half-life at that temperature be twice or more. However, E
It is preferable to apply a temperature of at least 90 ° C. to 180 ° C. for 10 minutes or more to the filling property of VA. More preferably, it is 110 ° C or higher and 160 ° C or lower. If it is lower than these lower limits, decomposition of the organic peroxide is insufficient, and E
The crosslinking of VA is significantly lower. If the cross-linking of EVA is insufficient, at high temperatures, the EVA flows and the entire coating material is wrinkled.
This wrinkle does not return to a wrinkle-free state even after being cooled, resulting in poor appearance. Alternatively, if the module is installed with an inclination, creep (EV
A shifts). If the temperature is higher than the upper limit temperature,
The filler EVA turns yellow and the initial conversion efficiency of the module is significantly reduced.

(Electron Beam Curing) It is preferable that the above crosslinking agent is added to the filler film, heated at a high temperature to complete the crosslinking, and then thermally bonded to the photovoltaic element. Alternatively, crosslinking can be achieved by irradiating the filler film with radiation. Generally, radiation is electron beam,
Although there is a gamma ray, an electron beam is preferably used industrially.

Electron beam irradiation apparatuses are roughly classified into a scanning type and a non-scanning type. 300 KeV or more for scanning type, 300 for non-scanning type
It is suitable for an acceleration 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 at least V.

The dose varies depending on the material used for the filler, but is preferably about 1 to 100 Mrad. 10
At a dose higher than 0 Mrad, the filler may turn yellow or generate heat to cause thermal decomposition. It is known that a crosslinking aid is used in combination for more efficient electron beam crosslinking. An example is triallyl isocyanuric acid.

[0055]

(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. Examples of the silane coupling agent include vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and 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.

Alternatively, instead of adding the silane coupling agent to the filler film, there is a method in which the silane coupling agent is applied on the photovoltaic element and dried. In this method, it is effective to wash excess silane coupling agent on the substrate with water or a solvent. In general, ethylene copolymers are inferior in light resistance to heat resistance,
More preferably, an ultraviolet absorber or a light stabilizer is added.

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

By containing a light stabilizer having an alkylated tertiary amine, a surface coating material having excellent light resistance and heat resistance can be obtained. 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) butanetetracarbonate, 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 exemplified.

The amount of the light stabilizer used can be determined as appropriate, but is generally preferably 0.01% to 5% with respect to the filler resin. More preferably, 0.05% to 0.1%.
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 preferably does not absorb the effective wavelength of the photovoltaic element. As the ultraviolet absorber suitably used in the present invention, an inorganic or high molecular weight ultraviolet absorber is desirable from the viewpoint of heat resistance and low volatility.

First, titanium oxide, zinc oxide and tin oxide are mentioned as inorganic ultraviolet absorbers. The particle size is preferably 50 nm or less which does not hinder the incidence of sunlight.
From the viewpoint of the absorption spectrum, zinc oxide is preferred.

On the other hand, as a high molecular weight ultraviolet absorber, 2-hydroxy-4- (methacryloyloxyethoxy) benzophenone is converted to methyl (meth) acrylate,
A method of copolymerizing with a monomer such as ethylene or ethylene-acryl ester may be used.

(Surface Film) Finally, the film used for the surface layer will be described. Since the film is located on the surface of the covering material of the solar cell module, it is necessary to ensure long-term reliability of the solar cell module in outdoor exposure, including weather resistance and contamination resistance. Materials preferably used in the present invention include polytetrafluoroethylene,
Examples include polyvinyl fluoride and polyvinylidene fluoride. From the viewpoints of transparency and adhesiveness, polyvinylidene fluoride can be suitably used. In order to improve the adhesiveness with the filler, it is desirable to perform corona treatment and plasma treatment.

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

[0066]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments. (Example 1) First, amorphous silicon (a-Si)
A solar cell (photovoltaic element) is manufactured. Figure 2 shows the fabrication procedure
This will be described with reference to FIG.

On a cleaned stainless steel substrate 201, a spa
Al layer (film thickness 5000)
Å) and a ZnO layer (thickness 5000 Å) are sequentially formed. One
Then, by plasma CVD, SiH_FourAnd PH_ThreeAnd H_Two
A-Si layer having n-type conductivity from a mixed gas of
H_FourAnd H_TwoA-Si layer having i-type conductivity from mixed gas of
With SiH_FourAnd BF_ThreeAnd H_TwoP-type microcrystals μ
Forming a c-Si layer, n-type layer thickness 150 ° / i-type layer thickness
4000Å / p-type layer thickness 100Å / n-type layer thickness 100Å
/ I-type layer thickness 800Å / p-type layer thickness 100Å
Forming a tandem type a-Si photoelectric conversion semiconductor layer 203;
Was. Next, as the transparent conductive layer 204, In _TwoO_ThreeThin film
700 mm thick)_TwoIn the atmosphere, steam In by resistance heating
Formed by wearing.

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

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

Next, the process of coating the photovoltaic element to form a solar cell module will be described with reference to FIG.
Galvalume steel plate (0.3 m
EVA (thickness: 460 μm) as the surface filler as the adhesive 305 on the back surface, the produced photovoltaic element 304, and a nonwoven glass fabric (Glasper GMC, trade name, manufactured by Honshu Paper Co., Ltd.) as the reinforcing material 303, basis weight 300g / m
² ) EVA (460 μm thick) blended as the surface filler 302 and an ethylene-tetrafluoroethylene copolymer film (Tefzel T2, trade name, manufactured by DuPont, 38 μm thick, uniaxially stretched film) as the surface layer 301 are sequentially laminated. did. Next, using a vacuum laminator,
Degassing, pressure bonding, and heating were performed. The degree of vacuum at this time is 1 mmH
g or less, heating is at 150 ° C. for 100 minutes. The module was taken out of 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), an accelerated weather resistance test was performed, and the conversion efficiency after 5000 hours was measured. However, photodegradation of amorphous silicon (Steplaron-Ski effect) was excluded. In addition, the numerical values in Table 1 are conversion efficiency change rates in which the conversion efficiency after the test is expressed in percentage based on 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) Moisture 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. Shunt resistance was measured. A change of -50% or more before and after the test was regarded as a pass, and a change less than -50% was rejected.

(4) Adhesive strength EVA and colored steel plates (wear-resistant color GL, wear-resistant black G
L540). The size of the material is 25 mm wide, the peeling speed is 50 mm / min, and the peeling direction is 180 ° peeling. 250 μm EVA breaks
Backed with a thick polycarbonate film.

(5) Initial Conversion Efficiency The conversion efficiency of the module was determined using an AM1.5 light source. The conversion efficiency was set to 1.00 in Example 1.

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

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 copolymer, copolymer weight ratio: 30 parts by weight: 7
A solar cell module was produced in exactly the same manner except that 0.5 parts by weight (0 parts by weight and a molecular weight of 350,000) was used.

Example 4 A solar cell module was produced in the same manner as in Example 1, except that 0.3 parts of 2-hydroxy-4-n-octoxybenzophenone was used as an ultraviolet absorber.

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

Example 6 A solar cell module was manufactured 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-
A solar cell module was produced in exactly the same manner except that 0.3 part of hydroxy-4-n-octoxybenzophenone (trade name: UV531 manufactured by Cyanamid) was used.

(Comparative Example 2) In Example 1, no light stabilizer was used, and 2-hydroxy-4-
n-octoxybenzophenone (manufactured by Cyanamid,
A solar cell module was produced in exactly the same manner except that 0.3 parts of trade name UV531) was used.

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

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

Comparative Example 5 In Example 1, 0.1% of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (trade name: Tinuvin 770, manufactured by Ciba Geigy) was used as a light stabilizer. Parts 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, trade name Lupazole 101, 1)
A solar cell module was produced in exactly the same manner except that the time half-life was 138 ° C.) and t-butyl peroxymaleic acid (Lupako PMA, trade name, manufactured by Atochem Yoshitomi, 1 hour half-life 110 ° C.).

Comparative Example 6 A solar cell module was produced in exactly the same manner as in Comparative Example 5, except that the lamination conditions were changed from 150 ° C. and 100 minutes to 122 ° C. and 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 has excellent weather resistance and heat resistance and can be used under severe outdoor conditions. No change in external appearance was observed in a temperature cycle test and a temperature / humidity cycle test assuming the use of. The deterioration of the moisture resistance test is remarkably small, and the adhesive strength is sufficiently large for practical use. Further, it can be seen that a module with high initial conversion efficiency can be manufactured.

Further, Examples 1 and 2 show that the weather resistance can be improved by using an inorganic UV absorber in combination. Example 3 shows that weather resistance can be improved also by using a high molecular weight ultraviolet absorber in combination.

Example 4 shows that the weather resistance can be improved by using a surface coating material containing a light stabilizer having a tertiary amine. From Example 5, the third
Coating material E containing light stabilizer having secondary amine
It can be seen that the use of EA can improve the weather resistance.

The method for coating the surface of the solar cell module according to the present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the invention.

[0092]

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 in the temperature cycle test and the temperature / humidity cycle test assuming the use of the material.

[Brief description of the drawings]

FIG. 1 is an example of a schematic sectional view of a solar cell module embodying 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 sectional view of another solar cell module of the present invention.

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

[Explanation of symbols]

Reference Signs List 101 substrate, 102 photovoltaic element, 103 back cover film, 104 back filler, 105 front transparent filler, 106 top surface film, 201 conductive substrate, 202 back reflection layer, 203 semiconductor photoactive layer , 204 transparent conductive layer, 205 current collecting electrode, 206 output terminal, 301 fluorine resin layer, 302 transparent filler on the surface, 303 reinforcing material, 304 photovoltaic element, 305 adhesive on the back surface, 306 reinforcing plate , 401 fluorine Base resin film, 402 thermoplastic transparent organic resin layer, 403 photovoltaic element, 404 insulator layer.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Yamada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Ayako Komori 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-6-169099 (JP, A) JP-A-6-85299 (JP, A) JP-A-4-188676 (JP, A) JP-A-63-168056 (JP, A A) JP-A-63-143879 (JP, A) JP-A-48-63690 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 31/04-31/078 H01L 31 / 0216

Claims (8)

(57) [Claims] 1. A solar cell module having a semiconductor photoactive layer as a light conversion member, a surface covering material including a transparent filler and a surface layer provided on a light incident side surface, and a reinforcing plate , wherein the filler is A solar cell module comprising a light stabilizer having an alkylated tertiary amine. 2. The solar cell module has a photovoltaic element in which a semiconductor photoactive layer as a light conversion member and a transparent conductive layer are formed on a conductive substrate, and the surface layer is the light incident side. The solar cell module according to claim 1, which is located on a surface. 3. The solar cell module according to claim 1, wherein the surface layer is made of a fluorine-based resin. 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 an unsaturated fatty acid ester copolymer resin. 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 covering 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 solar cell module has a range of from 00 to 200,000 Ωcm ² .