JP2000252491A - Method for manufacturing solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide thermal crosslinking conditions of resin for manufacturing a solar cell module with improved appearance and characteristics. SOLUTION: In a method for manufacturing a solar cell module for sealing a photovoltaic element with at least one type of resin containing at least one type of crosslinking agent, the temperature rise rate of the resin at a temperature where resolution per unit time of the crosslinking agent is maximized when thermally crosslinking the resin is made smaller than the maximum temperature rise rate of the resin at a temperature less than the one mentioned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a solar cell module, and more particularly to a method for cross-linking an organic resin composition in a solar cell module in which a photovoltaic element is sealed with the organic resin composition. is there.

[0002]

2. Description of the Related Art In recent years, awareness of environmental problems has been increasing worldwide. Above all, the danger of global warming caused by CO ₂ emission is serious, and the demand for clean energy is increasing more and more. Also, while the depletion of energy resources is a problem,
There is also a need for the development of new energy resources.
As an alternative energy source, at present solar cells are promising as a clean energy source because of their safety and ease of handling.

[0003] There are various types of solar cells. Representative examples are (1) crystalline silicon solar cells (2) polycrystalline silicon solar cells (3) amorphous silicon solar cells (including microcrystals here) (4) copper indium selenide solar cells (5) There are compound semiconductor solar cells and others. Among these, thin-film crystalline silicon solar cells, compound semiconductor solar cells, and amorphous silicon solar cells can be made relatively large in area at relatively low cost.

When a module is formed with these solar cells, it is necessary to cover the light incident side of the solar cell with a transparent covering material to protect the solar cell. Conventionally, glass or a transparent fluororesin such as a fluororesin film or a fluororesin paint is used on the outermost surface as the surface coating material, and various thermoplastic transparent organic resin compositions are used inside the transparent fluororesin.

The reason why a glass substrate is used as the outermost surface is that it has excellent weather resistance and can suppress a decrease in the conversion efficiency of the solar cell module due to a decrease in light transmittance due to deterioration. On the other hand, fluororesin is rich in weather resistance and water repellency, can reduce the decrease in the conversion efficiency of the solar cell module due to the decrease in light transmittance due to deterioration and dirt, and is lighter than the glass substrate. In addition, a highly flexible module can be provided.

Various types of thermoplastic transparent organic resin compositions have been used as sealing materials for bonding these surface coating materials to photovoltaic elements. Thermoplastic transparent resins are inexpensive and can be used in large quantities to protect the internal photovoltaic elements. Generally, ethylene-vinyl acetate copolymers (EV
A) or a thermoplastic transparent organic resin composition such as polyvinyl butyral (PVB) is used.

However, since the weather resistance of the thermoplastic transparent organic resin composition is not sufficient in several decades, clouding may occur due to partial gelation of the resin due to long-term outdoor exposure. In addition, an increase in the number of conjugated double bonds in the chemical bond causes yellowing of the resin, and it is inevitable that the conversion efficiency of the solar cell module decreases due to a decrease in the light transmittance of the resin.

Further, since this organic resin is usually thermoplastic, the resin softens and protects the element under a use condition in which the surface temperature of the solar cell module base becomes high under direct sunlight outdoors. There is a problem that performance cannot be exhibited as expected. In addition, the so-called microdelamining phenomenon, in which the adhesive force is reduced due to the softening of the organic resin and peels off from the upper covering material or the photovoltaic element, is sometimes observed.

In order to solve the above problem, it has been conventionally performed to include a crosslinking agent in a thermoplastic transparent organic resin composition as a sealing material to thermally crosslink the thermoplastic transparent organic resin composition. . For example, JP-A-58-60579 discloses a filling adhesive sheet for a solar cell comprising an ethylene-based copolymer resin containing a coupling agent and an organic peroxide. Further, as the ethylene copolymer resin, an ethylene copolymer having a vinyl acetate content of about 40% by weight or less is used.
It is described that vinyl acetate copolymer (EVA) is preferred, and more preferably 20 to 40% by weight.

[0010] However, the ethylene-vinyl acetate copolymer (EVA) disclosed in the above publication is a sealing material having good adhesion to glass and a fluororesin-based film and excellent flexibility. Therefore, it is necessary to heat at a temperature of about 100 to 200 ° C. for several tens minutes in order to decompose the organic peroxide and advance the crosslinking when sealing the solar cell. At this time, when the crosslinking temperature rises rapidly, crosslinking can be performed in a short time, but the decomposition rate of the organic peroxide increases, and the generated decomposition gas is not sufficiently degassed in the sealing material. Will remain as bubbles. In addition, the crosslinking speed becomes too high, and the degree of crosslinking becomes uneven, and the crosslinking of the sealing material proceeds and ends before the sealing material fills the irregularities of the photovoltaic element. For this reason, the unevenness of the photovoltaic element cannot be filled, resulting in poor filling of the solar cell module.

[0011] Such residual air bubbles and defective filling greatly impair the appearance of the solar cell module. In addition, these remaining bubbles and defective filling have a great influence on the long-term reliability of the solar cell module, and may cause defects such as delamination and current leakage from remaining bubbles and defective filling. Furthermore, in appearance, bubbles remain on the surface of the solar cell module, even in cases where poor filling is not observed, such bubbles remain or poor filling occurs on the back side of the photovoltaic element,
There is a risk of causing a failure that greatly affects the long-term reliability of the solar cell module.

[0012] Such a failure of the solar cell module depends on the manufacturing method. JP-A-09-364
According to Japanese Patent Publication No. 05 and Japanese Patent Application Laid-Open No. 09-312408, a single vacuum chamber method and a double vacuum chamber method have conventionally been used for manufacturing a solar cell module. In the single vacuum chamber system, evacuation and pressurization of the solar cell module are performed simultaneously. This has the drawback that the exhaust conductance becomes small and degassing of a certain degree or more becomes difficult, but the equipment is simple and the manufacturing process is also easy. On the other hand, in the double vacuum chamber system, it is possible to obtain a high degree of vacuum, it is possible to sufficiently remove the decomposition gas of the cross-linking agent, but equipment costs are high,
The manufacturing process is also complicated. Therefore, residual air bubbles and poor filling generated in the solar cell module are particularly concerned in a solar cell module manufactured by a single vacuum chamber method.

As a means for solving these problems, Japanese Patent Publication No. 06-052801 discloses a condition for producing a solar cell module having excellent appearance and characteristics by thermally crosslinking an ethylene-vinyl acetate copolymer (EVA). Is disclosed.

However, the conditions for thermal crosslinking of the ethylene-vinyl acetate copolymer (EVA) described in the above publication are limited in a very narrow range in both temperature and time.
It does not describe the rate of temperature rise of the ethylene-vinyl acetate copolymer (EVA). Also, the manufacturing method is limited to the double vacuum chamber system. For this reason, the crosslinking agent used for thermal crosslinking is limited to one in which crosslinking proceeds in a limited temperature range, and depending on the crosslinking agent used, bubbles remain even under the crosslinking conditions described in the above publication, Poor filling may occur. In addition, since the manufacturing method is also limited to the double vacuum chamber method, complicated devices and steps are required as compared with the single vacuum chamber method.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a resin cross-linking condition for producing a solar cell module having excellent appearance and characteristics in view of the above-mentioned conventional problems.

[0016]

Means for Solving the Problems The present inventors have conducted intensive research and development to solve the above problems, and as a result, have found that the following method for manufacturing a solar cell module is the best.

That is, a method of manufacturing a solar cell module according to the present invention is a method of manufacturing a solar cell module in which a photovoltaic element is sealed with at least one resin containing at least one crosslinking agent. When performing thermal crosslinking,
The rate of temperature rise of the resin at a temperature at which the amount of decomposition of the cross-linking agent per unit time is the maximum, the heating rate is set to be smaller than the maximum rate of temperature rise of the resin below the temperature. is there.

In the solar cell module manufactured according to the present invention, the resin is thermally cross-linked under the above-mentioned conditions. It is possible to provide a solar cell module having a better appearance than before. In addition, by suppressing the residual air bubbles and poor filling of the solar cell module, the reliability of delamination of the solar cell module, current leakage, etc., which has been caused by the residual air bubbles and poor filling, has been improved, and the long-term life of the solar cell module has been improved. Reliability can be ensured.

In particular, by setting the rate of temperature rise of the resin at 2.0 ° C./min or less at a temperature at which the amount of decomposition of the cross-linking agent is maximized, it is possible to further suppress the occurrence of residual bubbles and defective filling. .

Further, according to the present invention, it is possible to increase the rate of temperature rise to a temperature at which the amount of decomposition of the crosslinking agent contained in the resin per unit time is maximized, thereby greatly reducing the time required for crosslinking. Can be shortened. Conventionally, thermal crosslinking in a short time caused bubbles in the solar cell module to remain and poor filling.However, the rate of temperature rise at a temperature at which the amount of decomposition of the crosslinking agent per unit time was maximized was suppressed. By reducing the rate of heating up to the temperature at which the amount of decomposition per unit time is maximized, the generation of decomposition gas of the cross-linking agent is suppressed, and the remaining bubbles in the solar cell module and poor filling can be improved Thus, a solar cell module having excellent appearance and characteristics can be provided in a short time. In particular, it is effective to apply the conditions of the present invention to a surface sealing material for sealing the light receiving surface side of the photovoltaic element.

[0021] The resin is made of ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl methacrylate having excellent weather resistance. A copolymer (EMMA), an ethylene-methacrylic acid copolymer (EMAA), or an ethylene-vinyl acetate-based copolymer, an ethylene-methyl acrylate-based copolymer, an ethylene-ethyl acrylate-based copolymer, By using an ethylene-methyl methacrylate-based multi-component copolymer and an ethylene-methacrylic acid-based multi-component copolymer, it is possible to provide a solar cell module having excellent weather resistance and to further heat-resistant by thermally crosslinking the resin. It is possible to provide an excellent solar cell module.

An organic peroxide is used as the crosslinking agent, and the one-hour half-life temperature of the organic peroxide is 80 ° C. or more.
When the temperature is 40 ° C. or lower, it is suitable for effectively suppressing the generation amount of a decomposition gas of a crosslinking agent generated by thermal crosslinking.
This is because, when the one-hour half-life temperature is lower than 80 ° C., under the above conditions, a decomposition gas of the cross-linking agent may be generated below the softening point of the resin, and the resin may not be thermally cross-linked. Meanwhile, 1
If the time half-life temperature exceeds 140 ° C., the decomposition of the cross-linking agent is slow, so there is no rapid generation of decomposition gas, and the present invention does not necessarily need to be applied.

In the production of a solar cell module, there is a possibility that the degassing of the decomposition gas of the crosslinking agent is not sufficiently performed in the single vacuum chamber system as compared with the double vacuum chamber system. On the other hand, the double vacuum chamber system is more
The process was complicated. However, by performing thermal crosslinking of the resin under the conditions of the present invention, it is possible to suppress the generation of decomposition gas of the crosslinking agent, and it is possible to sufficiently deaerate even in a single vacuum chamber system. For this reason, by adopting a single vacuum chamber method in the manufacturing process of the solar cell module, the structure of the device and the process can be simplified, and a solar cell module having excellent appearance and characteristics can be manufactured.

[0024]

FIG. 1 shows a schematic configuration of a solar cell module according to the present invention. This solar cell module includes a photovoltaic element 101, a surface sealing material 102, a surface coating material 10
3, a back surface sealing material 104 and a back surface covering material 105; Here, light from the outside enters from the surface coating material 103 and reaches the photovoltaic element 101. Then, the electromotive force generated in the photovoltaic element 101 is taken out from an output terminal (not shown).

A reinforcing plate may be attached to the outside of the back surface covering material 105 in order to increase the mechanical strength of the solar cell module or to prevent distortion or warping due to a temperature change. As the reinforcing plate, for example, a steel plate, a plastic plate, or an FRP (glass fiber reinforced plastic) plate is suitably used.

(Photovoltaic element 101) Photovoltaic element 10
As one example, a semiconductor photoactive layer as a light conversion member is formed on a conductive substrate. FIG. 2 shows a schematic configuration thereof. The photovoltaic element 200 includes a conductive substrate 201, a back reflection layer 202, a semiconductor photoactive layer 203,
It comprises a transparent conductive layer 204 and a collecting electrode 205.

The conductive base 201 serves as a base for the photovoltaic element and also does not serve 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 on which a conductive layer is formed, 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. The metal layer includes, for example, Ti, Cr, Mo, W, Al, Ag, N
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 part for performing photoelectric conversion. Specific examples of the material include pn junction type polycrystalline silicon, pin junction type amorphous silicon, or CuInSe ₂ , CuInS ₂ , GaAs, CdS /
Cu ₂ S, CdS / CdTe, CdS / InP, CdT
e / Cu ₂ Te and other compound semiconductors. As the method of forming the semiconductor photoactive layer 203, 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 or the like as a raw material is used.
D, and in the case of a compound semiconductor, ion plating,
Ion beam deposition, vacuum deposition, sputtering,
Alternatively, there is an electrodeposition method.

The transparent conductive layer 204 functions as an upper electrode of the solar cell. As a material used for this, for example, In ₂ O ₃ , SnO ₂ , In ₂ O ₃ —SnO ₂ (IT
O), ZnO, TiO ₂ , Cd ₂ SnO ₄ , and a crystalline semiconductor layer doped with a high concentration of impurities. Examples of a method for forming the transparent conductive layer 204 include resistance heating evaporation, sputtering, spraying, CVD, and impurity diffusion.

A grid-like current collecting electrode 205 (grid) may be provided on the transparent conductive layer 204 in order to efficiently collect current. As a specific material of the collecting electrode 205, for example, Ti, Cr, Mo, W, Al, Ag,
Examples of the conductive paste include Ni, Cu, Sn, and silver paste. In addition, the collecting electrode 205
Are formed by sputtering using a mask pattern, resistance heating, CVD, a method of depositing a metal film on the entire surface and then removing unnecessary portions by etching, and forming a grid electrode pattern directly by optical CVD. A method of forming a negative electrode pattern of a grid electrode pattern, followed by plating, and a method of printing a conductive paste.

As the above-mentioned conductive paste, one obtained by dispersing silver, gold, copper, nickel, carbon or the like in the form of fine powder in a binder polymer is usually used. As the binder polymer, for example, a resin such as polyester, epoxy, acrylic, alkyd, polyvinyl acetate, rubber, urethane, and phenol may be mentioned.In order to take out an electromotive force at the end, the negative output terminal 206b is connected to the conductive substrate 201. Further, the plus side output terminals 206a are attached to the current collecting electrodes 205, respectively. Minus output terminal 2
A method of attaching the metal body 06b to the conductive substrate 201 by spot welding or soldering a metal body such as a copper tab is adopted. The current collecting electrode 2 of the positive output terminal 206a
A method of electrically connecting the metal body with a conductive paste or solder is adopted for the attachment to 05. Note that the positive output terminal 206a is insulated from the conductive base 201 and the like by the insulator 209.

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

(Back cover material 105) On the other hand, back cover material 1
Reference numeral 05 is necessary for maintaining electrical insulation between the conductive substrate of the photovoltaic element 101 and the outside. As the material,
Glasses and insulating resins that can ensure sufficient electrical insulation with the conductive substrate and have excellent long-term durability and can withstand thermal expansion and thermal contraction are available. In particular, nylon, polyethylene terephthalate (PET), and the like are examples of films that are preferably used as the backing material 105 as a material having flexibility.

(Back surface sealing material 104) Back surface sealing material 104
Is for bonding the photovoltaic element 101 and the back cover material 105. The material is preferably a material which can secure sufficient adhesiveness to the conductive substrate, has excellent long-term durability, can withstand thermal expansion and thermal contraction, and has flexibility.

Materials preferably used for the back surface sealing material 104 include ethylene-vinyl acetate copolymer (EVA),
Ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl methacrylate copolymer (EMMA),
Ethylene-methacrylic acid copolymer (EMAA), ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer Polymers, ethylene-methacrylic acid-based multi-component copolymers, hot melt materials such as polyvinyl butyral,
Double-sided tapes, flexible epoxy adhesives and the like can be mentioned.

When the solar cell module is used at a high temperature, for example, in the case of a roof material integrated type or the like, as described later, the surface sealing material 10 is used in order to ensure adhesion at a high temperature.
Desirably, crosslinking is performed in the same manner as in 2.

(Surface Sealant 102) Surface Sealant 102
Is to cover the unevenness of the photovoltaic element with resin, to protect the element from severe external environment such as temperature change, humidity, impact, etc., and to secure the adhesion between the surface covering material 103 and the photovoltaic element 101. is necessary. Therefore, the surface sealing material 102 includes
Weather resistance, adhesion, filling, heat resistance, cold resistance, impact resistance, etc. are required.

Examples of the resin satisfying these requirements include a polyolefin resin, a urethane resin and a silicone resin. Preferably, an ethylene-vinyl acetate copolymer (EVA) or an ethylene-methyl acrylate copolymer (EMA) is used. , Ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-methacrylic acid copolymer (EMAA), or ethylene-vinyl acetate multi-component copolymer, ethylene-methyl Acrylate-based multi-component copolymer, ethylene-ethyl acrylate-based multi-component copolymer,
It is desirable to use an ethylene-methyl methacrylate-based multi-component copolymer or an ethylene-methacrylic acid-based multi-component copolymer. Among them, particularly, ethylene-vinyl acetate copolymer (EVA) has well-balanced physical properties for use in solar cells and is preferably used.

In the present invention, a cross-linking agent is added to the surface sealing material resin, and thermal cross-linking is performed. In particular, the ethylene-vinyl acetate copolymer (EVA) has a low thermal deformation temperature as it is, and easily exhibits deformation and creep under high temperature use. Therefore, it is desirable to crosslink and increase heat resistance. The crosslinking agent is not particularly limited, but an organic peroxide can be suitably used. In particular, in the case of an ethylene-vinyl acetate copolymer (EVA), an organic peroxide is generally used.

Crosslinking with an organic peroxide is carried out 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. In the present invention, a thermal decomposition method is used.

In crosslinking by thermal decomposition of an organic peroxide,
Decomposition products of organic peroxide are generated as gas during crosslinking.
At this time, if the one-hour half-life temperature of the organic peroxide is less than 80 ° C., the crosslinking speed becomes too fast, and the degree of crosslinking becomes uneven, and the surface sealing material resin causes unevenness of the photovoltaic element. Crosslinking of the surface sealing material resin is completed before filling. Further, the generation of the decomposition gas becomes intense, and a phenomenon occurs in which the decomposition gas remains as bubbles in the solar cell module. On the other hand, when the temperature exceeds 140 ° C., the crosslinking speed is reduced, and the productivity of the solar cell module is reduced. Further, since the generation of the decomposition gas of the crosslinking agent per unit time becomes gentle, it is not necessary to suppress the decomposition gas of the crosslinking agent. Therefore, in order to effectively carry out the present invention, the one-hour half-life temperature of the organic peroxide is preferably 80 ° C. or more and 140 ° C. or less.

The amount of the organic peroxide to be added is preferably 0.5 to 5 parts by weight based on 100 parts by weight of the surface sealing resin.

The above-mentioned organic peroxides are roughly classified into hydroperoxides, dialkyl (allyl) peroxides, diacyl peroxides, peroxyketals, peroxyesters, peroxycarbonates and ketone peroxides.

Examples of the hydroperoxide include t-butyl peroxide, 1,1,3,3-tetramethylbutyl peroxide, p-menthane hydroperoxide, cumene hydroperoxide, p-cymene hydroperoxide, diisopropylbenzene peroxide, and 2,5-dimethylhexane. -2,5-didihydroperoxide, 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.

Examples of the diacyl peroxide 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.

Examples of the peroxyketal include 2,2-di-tert-butylperoxybutane, 1,1-di-tert-butylperoxycyclohexane, 1,1-di-tert-butylperoxycyclododecane, -(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.

Examples of the peroxyester include t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxyvivalate, t-butyl peroxy neodecanoate, t-butyl peroxy-
3,3,5-trimethylhesanoate, 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 can be mentioned.

Examples of the peroxycarbonate include t-butylperoxyisopropylcarbonate, di-n-propylperoxydicarbonate, di-sec-butylperoxydicarbonate, di (isopropylperoxy) dicarbonate, and di (2-ethylhexylperoxycarbonate). ) Dicarbonate, di (2-ethoxyethylperoxy) dicarbonate, di (methoxyidopropylperoxy) carbonate, di (3-methoxybutylperoxy) dicarbonate, bis- (4-t-butylcyclohexylperoxy) dicarbonate and the like.

As the ketone peroxide, acetylacetone peroxide, methyl ethyl ketone peroxide,
Examples include methyl isobutyl ketone peroxide, ketone peroxide and the like.

As other structures, vinyl tris (t-butylperoxy) silane and the like are also known.

In order to perform the above crosslinking reaction efficiently,
Triallyl isocyanurate (TA) called a crosslinking aid
It is desirable to use IC). The amount of the crosslinking assistant is generally 1 to 5 parts by weight based on 100 parts by weight of the surface sealing material resin.

A thermal antioxidant is often added to the resin of the surface sealing material 102 in order to impart stability at high temperatures. The appropriate amount of addition is 0.1 to 1 part by weight based on 100 parts by weight of the surface sealing material resin. The chemical structure of antioxidants is broadly classified into monophenol-based, bisphenol-based, polymer-type phenol-based, sulfur-based, and phosphoric-acid-based.

In the case of monophenol, 2,6-di-te
There are rt-butyl-p-cresol, butylated hydroxyanisole, and 2,6-di-tert-butyl-4-ethylphenol.

Examples of bisphenols 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.

As the high molecular phenol type, 1,1,3
-Tris- (2-methyl-4-hydroxy-5-ter
t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-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, 5H) trione, triphenol (vitamin E) and the like are known.

Examples of the sulfur type include dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiopropionate.

In the phosphoric acid system, triphenyl phosphite,
Diphenylisodecyl phosphite, phenyldiisodecyl phosphite, 4,4′-butylidene-bis- (3
-Methyl-6-tert-butylphenyl-di-tridecyl) phosphite, cyclic neopentanetetraylbis (octadecylphosphite), tris (mono and / or di) phenyl phosphite, diisodecinolepentaerythritol diphos Phyt, 9,10-dihydro-9-oxa-10-phosphaphenathrene-1
0-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.

The material of the surface sealing material 102 used in the present invention is excellent in weather resistance. However, in order to further improve the weather resistance or to protect the lower layer of the surface sealing material 102, an ultraviolet absorber is used. It is preferable to add at least one or more of these. The addition amount is about 0.1 to 0.5 parts by weight based on 100 parts by weight of the surface sealing material resin. Known compounds are used as the ultraviolet absorber. The chemical structure is roughly classified into salicylic acid, benzophenone, benzotriazole, and cyanoacrylate.

Examples of salicylic acids include phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate and the like.

Examples of the benzophenones include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, and 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.

As benzotriazoles, 2-
(2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tert)
-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-amylphenyl) 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.

Examples of the cyanoacrylates include 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate, ethyl-2-cyano-3,3'-diphenylacrylate and the like.

It is known that a hindered amine light stabilizer can be used as a method for imparting weather resistance other than the above-mentioned 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 of addition is 0.1 with respect to 100 parts by weight of the surface sealing material resin.
About 1 to 0.3 parts by weight is common. Of course, other than the hindered amine-based materials, those which function as light stabilizers are often colored, but are often colored.
02 is not desirable.

The hindered amine light stabilizers 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) separate,
Bis (1,2,2,6,2- (3,5-di-tert-4-hydroxybenzyl) -2-n-butylmalonic acid
6-pentamethyl-4-piperidyl) and the like are known.

It is preferable to use a low-volatility thermal oxidation inhibitor, an ultraviolet absorber and a light stabilizer in consideration of the usage environment of the solar cell module.

When it is assumed that the solar cell module is used in a more severe environment, it is preferable to improve the adhesion between the surface sealing material 102 and the photovoltaic element 101 or the surface covering material 103. A coupling agent such as a silane coupling agent or an organic titanate compound is used as a surface sealing material 10
By adding to 2, it is possible to improve the above adhesion. The amount of the coupling agent to be added depends on the surface sealing material resin 1
0.1 to 3 parts by weight per 100 parts by weight is preferable,
0.25 to 1 part by weight is more preferred.

Specific examples of the silane coupling agent include vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 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.

On the other hand, in order to minimize the decrease in the amount of light reaching the photovoltaic element 101, the light transmittance of the surface sealing material 102 must be 80% or more in the visible light wavelength region of 400 nm or more and 800 nm or less. Is desirable, and 90
% Is more desirable. Further, in order to facilitate the incidence of light from the atmosphere, the refractive index is preferably from 1.1 to 2.0, and more preferably from 1.1 to 1.6.

(Surface Coating Material 103) Surface Coating Material 103
Since it is located on the outermost layer of the solar cell module, it is necessary to have a property for ensuring long-term reliability of the solar cell module in outdoor exposure, including weather resistance, water repellency, stain resistance, and mechanical strength.

Materials preferably used in the present invention include glass, ethylene tetrafluoride-ethylene copolymer (ETFE), polyvinyl fluoride resin (PVF), polyvinylidene fluoride resin (PVDF), and polytetrafluoroethylene. Resin (TFE), ethylene tetrafluoride-propylene hexafluoride copolymer (FEP), poly (chlorotrifluoroethylene) resin (CTFE) and the like.

When glass is used for the surface coating material 103,
It is desirable to use a white-sheet tempered glass having excellent light transmittance, weather resistance and mechanical strength. However, when the solar cell module requires flexibility, a resin film is used because glass is inferior in flexibility. Above all, polyvinylidene fluoride resin is excellent from the viewpoint of weather resistance, and ethylene tetrafluoride-ethylene copolymer is excellent from the viewpoint of compatibility between weather resistance and mechanical strength.

When a resin is used for the surface covering material 103, the thickness of the surface covering material 103 must be increased to some extent in order to secure mechanical strength. There are also problems, specifically, 10
To 200 μm, more preferably 30 to 10 μm.
A thickness of 0 μm is required. In order to improve the adhesiveness with the surface sealing material 102, corona treatment, plasma treatment,
It is desirable to perform a chemical treatment or the like on the surface sealing material 103.

(Modularization) An example in which the conditions of the present invention are applied to the thermal crosslinking of the resin for the surface sealing material will be described below. It goes without saying that it can be applied to any of the materials.

In order to cover the light receiving surface of the photovoltaic element with the surface sealing material resin, a method of applying a sealing material resin dissolved in a solvent and then evaporating the solvent may be used. A method of uniformly adhering and melting the resin to the element, a method of extruding the heat-melted sealing material onto the element from the slit, and a step of extruding the heat-melted sealing material from the slit to produce a sheet of the sealing material and forming the element on the element. There is a method of heat-compression bonding on the top.

When the sealing material resin is dissolved in a solvent, various additives such as a crosslinking agent, a silane coupling agent, an ultraviolet absorber and an antioxidant are mixed at the same time. This is applied to a photovoltaic element and dried. Also, when the powdery sealing material resin is melted, or when the sealing material resin is melted and extruded, it is necessary to add an additive in advance.

When the surface sealing material 102 is formed on the photovoltaic element in advance, the back surface sealing material 104 and the back surface covering material 105 are laminated on the back surface, the surface covering material 103 is laminated on the front surface, and the surface is compressed by heating. The sealing material 102 is thermally crosslinked.

On the other hand, when the surface sealing material 102 is formed in a sheet shape, the photovoltaic element 101 and the surface coating material 1 are formed.
03 and heat-pressed in the same manner to form a surface sealing material 10
A solar cell module can be produced by thermally crosslinking 2.

As the method of thermocompression bonding, conventionally known vacuum lamination, roll lamination and the like can be variously selected and used. Conventionally, when performing vacuum lamination, a double vacuum chamber system has been used as a method for improving the degassing properties of a decomposition gas of a crosslinking agent generated by thermal crosslinking. However, the structure and lamination process of the double vacuum chamber system are complicated. According to the present invention, since the amount of decomposition gas generated by the crosslinking agent is suppressed, it is possible to use a single vacuum chamber system whose structure and process are simplified as compared with the double vacuum chamber system.

Here, an example of vacuum lamination using a single vacuum chamber system will be described in detail with reference to FIG.

First, as shown in FIG. 4, a photovoltaic element 401, a nonwoven fabric 402, a surface covering material 404, a back surface covering material 405, a sheet-like surface sealing material 403 and a back surface sealing material 406 are superposed to form a solar cell module laminate. 400.

Next, as shown in FIG.
04 on a plate 301 and a silicone rubber sheet 3
Layer 02. Thereafter, the laminate 30 is formed by the following steps.
4 are pasted together.

(First Step) As shown in FIG. 3B, the laminate 304 is pressed by a silicon rubber sheet 302 by exhausting air from an exhaust port 305 of the plate 301.

(Second Step) The plate 301 is heated to a temperature at which the sealing material causes a crosslinking reaction, and the temperature is maintained until the crosslinking is completed.

At this time, in order to obtain a solar cell module having excellent appearance and characteristics, the heating rate at a temperature at which the amount of decomposition of the cross-linking agent per unit time is the maximum is made higher than the maximum heating rate at a temperature lower than the above-mentioned temperature. It is necessary to make it smaller. Further, it is more preferable that the rate of temperature rise at a temperature at which the amount of decomposition of the crosslinking agent per unit time is the maximum is 2.0 ° C./min or less. As for the crosslinking time, the heating and pressurization is generally completed at a temperature and time at which the thermal decomposition proceeds at 90%, preferably 95% or more.

(Third Step) After cooling, the module is taken out.

[0088]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments.

(Example 1) [Photovoltaic element] First, amorphous silicon (a-S
i) Produce a solar cell (photovoltaic element). The manufacturing procedure will be described with reference to FIG.

On a cleaned stainless steel substrate as the conductive substrate 201, A was formed as a back reflection layer 202 by sputtering.
l layer (500 nm thick) and ZnO layer (500 nm thick)
Are sequentially formed.

Then, the SiH was formed by plasma CVD.
₄ and PH ₃ and the n-type a-si layer from a mixed gas of H _2, Si
An i-type a-Si layer is formed from a mixed gas of H ₄ and H ₂ , and a p-type microcrystalline μc-Si layer is formed from a mixed gas of SiH ₄ , BF ₃ and H _2. 400 nm / p layer thickness 10 nm / n layer thickness 10 nm / i layer thickness 80 nm / p
A tandem a-si photoelectric conversion semiconductor layer 203 having a layer thickness of 10 nm was formed.

Next, as the transparent conductive layer 204, In ₂ O ₃
A thin film (thickness: 70 nm) was formed by vapor deposition of In in a O ₂ atmosphere by a resistance heating method. Further, a grid electrode as the current collecting electrode 205 is formed by screen printing of silver paste, and finally, a copper tab is attached to the conductive substrate 201 as the negative terminal 206b using the stainless solder 208, and a tin foil is used as the positive terminal 206b. This tape was attached to the current collecting electrode 205 with the conductive adhesive 207 to serve as an output terminal to obtain a photovoltaic element.

Then, the devices were connected in series to form a cell block having an outer dimension of 300 mm × 1200 mm.

[Modularization] A method of manufacturing a solar cell module by covering the cell block will be described with reference to FIG.

The cell block 501, the surface sealing material 502,
EVA sheet as backside sealing material 507 and backside reinforcing material adhesive layer 508, ETFE film as surface covering material 503, glass fiber nonwoven fabric as nonwoven fabric 504, PET film as backing material 505, backside reinforcing material 506
Galvalume sheet as ETFE film / EV
A sheet / glass fiber nonwoven fabric / cell block / EVA sheet / PET film / EVA sheet / galvalume steel sheet were stacked in this order to form a laminate 500. The nonwoven fabric 504 is
In addition to assisting deaeration of air in the gap between the laminates in the exhaust step, the surface covering material 502 functions as a reinforcing material for the surface sealing material 502 by being impregnated with the surface sealing material 502 in the heating step. In some cases,
It also has the additional effect of making it difficult for surface scratches to reach the element. The ETFE film is obtained by subjecting the adhesive surface of EVA to plasma treatment.

The EVA sheet used was 1.5 parts by weight of a crosslinking agent, 0.3 parts by weight of an ultraviolet absorber, and 0.1 parts by weight of a light stabilizer based on 100 parts by weight of an EVA resin (vinyl acetate content: 33%). Parts by weight, 0.2 parts by weight of an antioxidant, and 0.25 parts by weight of a silane coupling agent. The crosslinking agent used was an organic peroxide 1,1-di-t-butylperoxycyclododecane (1 hour half-life temperature 114.0 ° C.).
It is.

The laminate was placed on a plate of a laminating apparatus of a single vacuum chamber type with the ETFE film side up, and a silicon rubber sheet was laminated. Next, air was exhausted from the exhaust port of the plate using a vacuum pump, and the rubber was adsorbed to the plate. After evacuation for 30 minutes at a vacuum of 5 Torr,
The laminate 500 was heated by a heater embedded in the plate.

FIG. 6 shows the heating conditions of the sealing material. At this time, the temperature at which the amount of decomposition of the crosslinking agent per unit time is maximum is 1
44 ° C. and 144 in the sealing material (EVA sheet)
The maximum heating rate below 3.5 ° C. is 3.5 ° C./min, and the heating rate at 144 ° C. is 1.25 ° C./min. Thereafter, the heater was turned off, air was sent by a fan to cool the plate to about 40 ° C., and then the exhaust was stopped and the solar cell module was taken out.

The solar cell module manufactured by the above method was evaluated for the items described below.

Example 2 In Example 1, an organic peroxide t-butyl peroxybivalate (one-hour half-life temperature: 72.7 ° C.) was used as a crosslinking agent. The heating conditions of the sealing material are shown in FIG. At this time, the temperature at which the amount of decomposition of the crosslinking agent per unit time becomes maximum is 97 ° C., and the sealing material (EVA) is used.
Sheet) at a temperature lower than 97 ° C. has a maximum heating rate of 3.1.
The heating rate at 7 ° C./min and 97 ° C. is 1.75 ° C./min.

(Example 3) In Example 1, E was used as the sealing material.
An EA sheet was used. The EEA sheet used here is E
An EA resin (ethyl acrylate content: 20%) was mixed with the same additives as in Example 1, and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (1 hour half-life temperature) was used as a crosslinking agent. 138.1 ° C). The heating conditions of the sealing material are shown in FIG. At this time, the temperature at which the amount of decomposition of the crosslinking agent per unit time is maximum is 166 ° C.
The maximum heating rate below 3.degree. C. is 3.67.degree. C./min, and the heating rate at 166.degree. C. is 2.0.degree. C./min.

(Example 4) In Example 1, E was used as the sealing material.
An EA sheet was used. The EEA sheet used here is E
The same additives as in Example 1 were blended with the EA resin (ethyl acrylate content: 20%), and 2,4-dichlorobenzoyl peroxide (1 hour half-life temperature 73.30%) was used as a crosslinking agent.
0 ° C.). The heating conditions of the sealing material are shown in FIG. At this time, the temperature at which the amount of decomposition of the crosslinking agent per unit time is the maximum is 95 ° C., and the temperature of the sealing material (EEA sheet) is 9
The maximum heating rate at less than 5 ° C. is 3.67 ° C./min, and the heating rate at 95 ° C. is 1.25 ° C./min.

(Embodiment 5)
The composition of No. 0 is ETFE film / EVA sheet / glass fiber nonwoven fabric / cell block / EEA sheet / PET film / EEA sheet / galvalume steel sheet, and 1,1-di-t-butylperoxycyclododecane ( 1 hour half-life temperature 114.0 ° C), E
2,5-dimethyl-2,5 as a crosslinking agent in the EA sheet
-Di (t-butylperoxy) hexane (1 hour half-life temperature 138.1 ° C) was used. The EVA sheet used in Example 1 was applied to EVA resin (vinyl acetate content: 33%).
In the EEA sheet, the same additives as in Example 1 were mixed in the EEA resin (ethyl acrylate content: 20%).

FIG. 6 shows the heating conditions of the sealing material. At this time, the temperature at which the amount of decomposition of the crosslinking agent per unit time is the maximum is
The temperature of 1,1-di-t-butylperoxycyclododecane in the EVA sheet is 143 ° C., and the maximum heating rate at less than 143 ° C. in the sealing material (EVA sheet) is 5.0 ° C.
/ Min, the rate of temperature rise at 143 ° C is 1.0 ° C / min. On the other hand, 2,5-dimethyl-2,5 which is a crosslinking agent in EEA
The temperature at which the amount of decomposition of di (t-butylperoxy) hexane per unit time is maximum is 159 ° C., and the maximum rate of temperature rise of the sealing material (EEA sheet) below 159 ° C. is 5.0 ° C. / Min, the rate of temperature rise at 159 ° C is 1.0 ° C /
Minutes.

(Example 6) In Example 1, E was used as the sealing material.
MA sheets were used. The EMA sheet used here is E
MA resin (methyl acrylate content: 22%) was mixed with the same additives as in Example 1, and t-butyl peroxyisobutyrate (1 hour half-life temperature: 96.4) was used as a crosslinking agent.
° C) was used. The heating conditions of the sealing material are shown in FIG. At this time, the temperature at which the amount of decomposition of the cross-linking agent per unit time is the maximum is 119 ° C.
The maximum heating rate below 9 ° C is 3.67 ° C / min, 119 ° C
Is 1.0 ° C./min.

(Example 7) In Example 1, the sealing material was heated under the heating conditions shown in FIG. At this time, the temperature at which the amount of decomposition of the cross-linking agent per unit time becomes the maximum is 149 ° C., and the maximum temperature rising rate of the encapsulant (EVA sheet) at less than 149 ° C. is 3.33 ° C./min. Is 2.2 ° C./min.

Example 8 In Example 1, the sealing material was heated under the heating conditions shown in FIG. At this time, the temperature at which the amount of decomposition of the cross-linking agent per unit time becomes the maximum is 149 ° C., and the maximum temperature rising rate of the encapsulant (EVA sheet) at less than 149 ° C. is 3.33 ° C./min. Is 2.5 ° C./min.

Example 9 In Example 1, the sealing material was heated under the heating conditions shown in FIG. At this time, the temperature at which the amount of decomposition of the cross-linking agent per unit time is the maximum is 150 ° C., and the maximum heating rate of the sealing material (EVA sheet) below 150 ° C. is 3.33 ° C./min. Is 2.8 ° C./min.

Example 10 In Example 3, the sealing material was heated under the heating conditions shown in FIG. At this time, the temperature at which the amount of decomposition of the cross-linking agent per unit time is maximum is 167 ° C., and the maximum heating rate of the sealing material (EEA sheet) below 167 ° C. is 3.67 ° C. Is 2.4 ° C./min.

(Comparative Example 1) In Example 1, the sealing material was heated under the heating conditions shown in FIG. At this time, the temperature at which the amount of decomposition of the cross-linking agent per unit time is the maximum is 151 ° C., and the maximum heating rate of the sealing material (EVA sheet) at less than 151 ° C. is 3.17 ° C./min. Is 3.5 ° C./min.

(Comparative Example 2) In Example 2, the sealing material was heated under the heating conditions shown in FIG. At this time, the temperature at which the amount of decomposition of the cross-linking agent per unit time is maximum is 101 ° C., and the maximum rate of temperature rise of the sealing material (EVA sheet) at less than 101 ° C. is 2.63 ° C./min, 101 ° C. Is 2.63 ° C./min.

Comparative Example 3 In Example 3, the sealing material was heated under the heating conditions shown in FIG. At this time, the temperature at which the amount of decomposition of the cross-linking agent per unit time is the maximum is 170 ° C., and the maximum rate of temperature increase of the sealing material (EEA sheet) below 170 ° C. is 3.67 ° C. Is 4.0 ° C./min.

(Comparative Example 4) In Example 4, the sealing material was heated under the heating conditions shown in FIG. At this time, the temperature at which the amount of decomposition of the cross-linking agent per unit time is the maximum is 102 ° C., and the maximum rate of temperature rise at less than 102 ° C. in the sealing material (EEA sheet) is 2.71 ° C./min, 102 ° C. Is 3.18 ° C./min.

(Comparative Example 5) In Example 5, the sealing material was heated under the heating conditions shown in FIG. At this time, the temperature at which the amount of decomposition of the cross-linking agent per unit time is the maximum is 145 ° C. for 1,1-di-t-butylperoxycyclododecane in the EVA sheet, and 14 ° C. for the sealing material (EVA sheet).
The maximum heating rate below 5 ° C. is 3.6 ° C./min, and the heating rate at 145 ° C. is 3.6 ° C./min. On the other hand, 2,5-dimethyl-2,5-di (t-) which is a crosslinking agent in the EEA sheet is used.
The temperature at which the amount of decomposition of butylperoxy) hexane per unit time is maximum is 156 ° C., and the maximum rate of temperature rise below 3.6 ° C. in the sealing material (EEA sheet) is 3.6 ° C.
The rate of temperature rise at 156 ° C./min is 3.6 ° C./min.

(Comparative Example 6) In Example 6, the sealing material was heated under the heating conditions shown in FIG. At this time, the temperature at which the amount of decomposition of the cross-linking agent per unit time is the maximum is 126 ° C., and the maximum temperature rising rate of the sealing material (EMA sheet) at less than 126 ° C. is 4.0 ° C./min. Is 4.0 ° C./min.

(Evaluation Results) The following items were evaluated for the solar cell modules manufactured in the above-described Examples and Comparative Examples. Table 1 shows the results. Table 1 also shows the one-hour half-life temperature of the used crosslinking agent and the rate of temperature increase at the temperature at which the amount of decomposition of the crosslinking agent per unit time is maximized.

(1) Remaining air bubbles in the module The number of air bubbles remaining in the sealing material of the module after thermal crosslinking was counted. Air bubbles were all visible to the naked eye.

(2) Temperature Cycle A temperature cycle test of −40 ° C./1 hour and 90 ° C./1 hour was performed 50 times, and changes in the appearance of the solar cell module after the test were observed. Those with no change were marked with a circle, and those with a change were briefly commented on.

(3) Temperature / humidity cycle A temperature / humidity cycle test of −40 ° C./1 hour and 85 ° C./85% RH / 4 hours was performed for 50 cycles, and changes in the appearance of the solar cell module after the test were observed. Those with no change were marked with a circle, and those with a change were briefly commented on.

(4) Degree of Crosslinking 1 g of the sealing material after thermal crosslinking was subjected to Soxhlet extraction with xylene for 6 hours, and the degree of crosslinking (%) = [(weight of undissolved sealing material) / (before Soxhlet extraction) Weight of sealing material)] × 10
It was determined from 0 (%).

[0121]

[Table 1]

As is clear from Table 1, each of the solar cell modules of the examples could be a solar cell module in which residual air bubbles were suppressed. In addition, no problems were found in the temperature cycle test and the temperature / humidity cycle test for any of the modules of the examples. It was also found that the degree of crosslinking of the sealing material was 80% or more and the crosslinking was sufficiently crosslinked.

FIG. 9 shows the relationship between the rate of temperature rise of the sealing material and the remaining bubbles. According to this, air bubbles remaining in the sealing material are generated at a temperature at which the amount of decomposition of the cross-linking agent is maximized, where the rate of temperature rise of the sealing material is greater than 2.0 ° C./min. Therefore, by setting the rate of temperature rise of the sealing material at a temperature at which the amount of decomposition of the cross-linking agent is maximized to 2.0 ° C./min or less, it is possible to manufacture a solar cell module in which no bubbles remain in the appearance.

On the other hand, in each of Comparative Examples 1 to 6, the obtained solar cell modules were sufficiently crosslinked, but vigorous air bubbles were observed in appearance. In addition, it can be seen that by performing the temperature cycle test and the temperature / humidity cycle test, expansion of bubbles and peeling of the sealing material occur.

By controlling the relationship between the amount of decomposition of the crosslinking agent and the temperature and the rate of temperature rise of the sealing material from the examples and comparative examples, a stable supply of a solar cell module having an excellent appearance can be achieved.

Incidentally, the solar cell module according to the present invention is not limited to the above-mentioned embodiments at all, and can be variously modified within the scope of the gist.

[0127]

As is apparent from the above description, the method for manufacturing a solar cell module according to the present invention is characterized in that the temperature at which the amount of decomposition per unit time of the cross-linking agent contained in the sealing material made of resin is maximized. Is characterized in that the encapsulant is thermally crosslinked under heating conditions in which the rate of temperature rise is lower than the maximum rate of temperature rise below the temperature. As a result, it is possible to suppress the amount of decomposed gas generated per unit time from the cross-linking agent, to stably supply a solar cell module having an excellent appearance without bubbles remaining and poor filling, and for various cross-linking agents. Thus, it is possible to easily determine a sealing method and a manufacturing method of the solar cell module.

[Brief description of the drawings]

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

2A is a cross-sectional view showing a basic configuration of a photovoltaic element used in the solar cell module of FIG. 1, and FIG. 2B is a top view similarly viewed from a light receiving surface side.

FIG. 3 is a schematic view showing an example of a manufacturing process of a solar cell module by a single vacuum chamber method.

FIG. 4 is an example of a solar cell module laminate.

FIG. 5 is a schematic sectional view of the solar cell module laminate of Example 1.

FIG. 6 shows heating conditions of a sealing material in Examples 1 to 6.

FIG. 7 shows heating conditions of a sealing material in Examples 7 to 10.

FIG. 8 shows heating conditions of a sealing material in Comparative Examples 1 to 6.

FIG. 9 shows the relationship between the rate of temperature rise of the sealing material and residual air bubbles in the example.

[Explanation of symbols]

 101, 401 Photovoltaic element 102, 403, 502 Surface sealing material 103, 404, 503 Surface coating material 104, 406, 507 Back surface sealing material 105, 405, 505 Back surface coating material 201 Conductive substrate 202 Back surface reflective layer 203 Semiconductor photoactive layer 204 Transparent conductive layer 205 Current collecting electrode 206a Positive output terminal 206b Negative output terminal 207 Conductive adhesive 208 Stainless solder 209 Insulator 301 Metal plate 302 Silicon rubber sheet 304, 400, 500 Solar cell module laminate 303 O-ring 305 Exhaust port 306 Vacuum pump 402, 504 Non-woven fabric 501 Cell block 506 Steel plate 508 Backside reinforcing material adhesive layer

Continued on the front page (72) Inventor Satoshi Yamada 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Hidenori Shiozuka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. F-term (reference) 5F051 BA18 CB29 CB30 EA18 JA04 JA05

Claims (6)

[Claims] 1. A method for manufacturing a solar cell module in which a photovoltaic element is sealed with at least one resin containing at least one cross-linking agent. A method for manufacturing a solar cell module, wherein the rate of temperature rise of the resin at a temperature at which the amount of decomposition per unit time is the maximum is made smaller than the maximum rate of temperature rise of the resin below the temperature, and heating is performed. . 2. The method according to claim 1, wherein the resin is a surface sealing material for sealing a light receiving surface side of the photovoltaic element.
A method for manufacturing the solar cell module according to the above. 3. The method according to claim 1, wherein the rate of temperature rise of the resin at a temperature at which the amount of decomposition of the crosslinking agent per unit time is the maximum is 2.0 ° C./min or less. A method for manufacturing a solar cell module. 4. The resin according to claim 1, wherein the resin is ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), or ethylene-methyl methacrylate copolymer. (EMMA), ethylene-methacrylic acid copolymer (EMAA), or ethylene-vinyl acetate-based copolymer, ethylene-methyl acrylate-based copolymer, ethylene-ethyl acrylate-based copolymer, ethylene-methyl The method for producing a solar cell module according to any one of claims 1 to 3, wherein the method is selected from a methacrylate-based multi-component copolymer and an ethylene-methacrylic acid-based multi-component copolymer. 5. The method for manufacturing a solar cell module according to claim 1, wherein the crosslinking agent is an organic peroxide, and the one-hour half-life temperature is 80 ° C. or more and 140 ° C. or less. 6. The method for manufacturing a solar cell module according to claim 1, wherein the thermal crosslinking of the resin is performed by a single vacuum chamber laminator.