JPH08139347A - Solar cell module and manufacture thereof - Google Patents

Abstract

PURPOSE: To reduce light reflected directly by a surface and prevent stripping by forming recesses and projections in the surface of a coating material, and controlling to specific values the maximum difference in height between any adjacent recess and projection and the distance between the troughs of any adjacent recesses or between the crests of any adjacent projections. CONSTITUTION: External light comes in through a surface resin film 103, passes through a transparent surface sealing material 102, and reaches a photoelectromotive force element 101. The resultant photoelectromotive force is externally taken out. The surface sealing material 102 covers the uneven surface of the photoelectromotive force element with resin, and further bonds the surface resin film 103 to the photoelectromotive force element 101. The surface resin film 103 has weatherability, mechanical strength and so on, and remains reliable even if exposed to weather, for example, for a long time. Recesses and projections are formed both in the surface resin film 103 and in the surface sealing material 102. The maximum difference in height between any adjacent recess and projection is controlled to 5μm or above and 500μm or below. The maximum distance between the troughs of any adjacent recesses or between the crests of any adjacent projections is controlled to 0.1mm or above and 10mm or below.

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 a method for manufacturing the same, and more particularly to a solar cell module coated with a coating material containing at least two layers of a transparent organic polymer resin and a transparent surface protective film on the outermost surface. The present invention relates to a solar cell module in which the light incident side of an electromotive force element is sealed on its surface, and a method for manufacturing the same.

[0002]

_2. Description of the Related Art In recent years, while awareness of environmental problems has been increasing worldwide, the danger of global warming due to CO ₂ emission is serious and there is a desire for clean energy. It is getting stronger and stronger.
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. Typical examples are (1) crystalline silicon solar cells (2) polycrystalline silicon solar cells (3) amorphous silicon solar cells (4) copper indium selenide solar cells (5) compound semiconductor solar cells. Among them, 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, and therefore, research and development have recently been actively pursued in various fields.

Further, among these solar cells, a thin-film solar cell typified by an amorphous silicon solar cell in which silicon is deposited on a conductive metal substrate and a transparent conductive layer is formed on the conductive metal substrate is lightweight and has high impact resistance. Since it is highly flexible and flexible, it is expected to be a future module form. However, unlike the case of depositing silicon on a glass substrate, it is necessary to protect the solar cell by covering the light incident side surface with a transparent coating material. Therefore, conventionally, by using a transparent fluoride polymer thin film such as a fluorine oil film on the outermost surface as a surface coating material, and various thermoplastic transparent organic resins on the inside, a light weight utilizing the characteristics of a thin film solar cell is provided. A flexible solar cell module has been proposed. The reasons why these materials have been used are as follows: 1) Fluoride polymers are rich in weather resistance and water repellency, and are caused by yellowing and white turbidity due to deterioration of resin, or reduction in light transmittance due to surface stains. It is possible to reduce the decrease in conversion efficiency of the solar cell module.

2) The thermoplastic transparent resin is inexpensive and can be used in a large amount as a sealing material for protecting the internal photovoltaic element.

[0006] There is such a thing. Further, on the solar cell element are generally provided various collecting electrodes for efficiently extracting the generated electric power and metal members for serializing or parallelizing the elements, and the thermoplastic transparent organic resin Also has an effect of filling the irregularities on the element surface and smoothing the surface of the coating material by sealing such a mounting member such as an electrode or a metal member.

FIG. 9 shows a conventional example of such a solar cell module. In FIG. 9, 902 is a fluoride polymer thin film layer, 903 is a thermoplastic transparent organic resin, 901 is a photovoltaic element, and 904 is an insulator layer. In this example, the same organic resin as the light receiving surface is also used on the back surface. More specifically, the fluorinated polymer thin film layer is an ETFE (ethylene-tetrafluoroethylene copolymer) film, PVF.
It is a fluororesin film such as a (polyvinyl fluoride) film, the thermoplastic transparent organic resin is EVA (ethylene-vinyl acetate copolymer), butyral resin, etc., and the insulating layer is a nylon film or an aluminum laminated Tedlar film. It is various organic resin films including the first. In this example, the thermoplastic transparent organic resin 903 serves as an adhesive between the photovoltaic element 901 and the fluororesin film and the insulating layer 904, fills the irregularities of the surface mounting member, and scratches and shocks from the outside to the solar cell. Plays a role as a sealing material for protecting the.

However, the surface of a conventional solar cell module whose surface is coated with a fluororesin film is usually smooth. Therefore, light incident at an angle close to parallel to the surface is totally reflected when it exceeds the critical angle, and as shown in FIG. 5, a solar cell module is installed on a roof of a house, a roof of a building, a wall surface, or the like. In this case, depending on the angle, the reflected light reaches other houses or the ground, which causes a problem that people there are dazzled and uncomfortable.

On the other hand, the adhesive force between the fluororesin film and the organic resin is generally extremely weak. Therefore, in order to solve this, it is common practice to subject the fluororesin film to corona discharge treatment to improve the adhesive force with the organic resin. However, this is still insufficient, and peeling of the film occurs when the solar cell module is exposed outdoors for a long time.

When the outermost surface is covered with a film,
There is a problem that wrinkles are easily formed on the film. For example, in order to attach the film to the organic resin in the coating material forming step, a method of vacuum heating and pressure bonding using a laminator is generally used, but if the film becomes loose during the pressure bonding, wrinkles occur. In addition, even if the initial appearance is good, thermal expansion of the coating material after long-term outdoor exposure,
Wrinkles may occur on the surface film due to repeated heat shrinkage. Furthermore, if the surface is smooth, even small wrinkles are conspicuous, and the appearance is likely to be poor.

JP-A-60-88481 discloses a solar cell module in which the surface roughness Rmax of the surface protective layer is 0.3 to 100 μm. Among them, because the surface roughness is the above value, the effect that electromotive force shortage does not occur even if the solar cell is used in a state where the amount of light is small and the incident angle is large such as in the early morning or the evening is claimed. There is. However, in the above publication, only a solar cell used in a device such as an electric desk calculator is described, and a solar cell module used outdoors for electric power is not mentioned at all. Therefore, the above-mentioned drawbacks that are particularly problematic in such applications, that is, the influence of reflected light on the periphery, peeling of the surface film, wrinkles of the surface film, etc. are not mentioned at all. Further, the pitch of the unevenness on the surface is not particularly mentioned, and if the pitch is extremely large, the pitch becomes almost smooth and the above problem cannot be solved. Therefore, the shape of the surface covering material that solves the above-mentioned problems associated with the solar cell module for electric power using the film and the sealing resin as the surface covering material is not known.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned drawbacks, the present invention has a small amount of direct reflected light on the surface, has a good adhesive force between the surface film and the organic resin for sealing, and has a wrinkle on the surface film. An object of the present invention is to provide a highly reliable solar cell module that is hard to enter and has no film peeling or wrinkles even after long-term outdoor exposure, and a method for manufacturing the same.

[0013]

As a result of intensive research and development for solving the above problems, the present inventor has found that the following method is the best. That is, the present invention
A transparent organic polymer resin layer provided on the light-incident side surface of a photovoltaic element and a transparent surface protective film located on the outermost surface in contact with the transparent organic polymer resin layer are covered with a coating material containing at least two layers. In the solar cell module,
Unevenness is formed on the surface of the coating material, the maximum height difference between the adjacent concave portions and the convex portions is 5 μm or more and 500 μm or less, and the distance between the adjacent concave portions and the concave portions or the apex of the adjacent convex portions and the convex portions is It is characterized in that the maximum is 0.1 mm or more and 10 mm or less.

[0014]

According to this method, the following effects can be expected. (1) Direct reflection on the surface is reduced. That is, as shown in FIG. 6, the sunlight does not totally reflect on the surface of the module when the incident angle of the sunlight becomes large, and the reflected light does not cause discomfort to the surrounding people. (2) Peeling between the surface protective film and the organic polymer resin layer can be suppressed. That is, by forming irregularities on the surface, the contact area between the film and the resin layer increases, and the adhesive strength is essentially improved. (3) The occurrence of wrinkles in the surface protective film can be suppressed. That is, even if the film is loosened during the coating forming step, the film is pushed into the concave portion, so that the looseness of the film is eliminated and the problem that wrinkles occur during pressure bonding can be solved. Furthermore, even if the thermal expansion and contraction of the coating material is repeated during outdoor exposure, the unevenness formed on the surface relieves the stress applied to the surface film during expansion and contraction and suppresses the generation of wrinkles. be able to. On the other hand, even if a wrinkle occurs, if it is a minute wrinkle, it will be distracted by the uneven shape of the surface, and will not be a defect in appearance.

The thickness of the surface protection film is 20.
By being in the range from μm to 200 μm, (4) the effect of (3) above can be maximized. That is, when the surface of the film having the above-mentioned thickness is smooth, wrinkles are likely to occur, and the wrinkle problem is remarkably improved by making the surface uneven.

The surface protective film is made of a resin selected from acrylic resins and fluoride polymers, whereby (5) a coating having excellent weather resistance is obtained. That is, the weather resistance of the acrylic resin and the fluoride polymer can be expected. Further, when a fluoride polymer is used, the water repellency of the module surface is improved, the contamination of the solar cell module surface during long-term outdoor exposure can be suppressed, and the reduction in conversion efficiency can be reduced.

The main component of the surface organic polymer resin is polyvinyl butyral, ethylene-vinyl acetate copolymer (EV
(6) It is a resin that has been conventionally used as a coating material for a solar cell module by being made of a resin selected from any one of A), and the above-mentioned effects can be obtained without significantly changing the current coating material configuration. Can be obtained.

By using a tetrafluoroethylene-ethylene copolymer among the above-mentioned fluoride polymers, (7) the weather resistance, transparency and mechanical strength of the tetrafluoroethylene-ethylene copolymer are utilized. It becomes a coating.

Since the surface protective film is a resin film which has not been stretched, (8) it is possible to prevent cracking of the surface film at the bottom of the concave and convex portions of the surface covering material. That is, in a solar cell module using a stretched resin film on the surface, when unevenness is formed on the surface, cracks in the stretching direction may occur at the bottom of the recess, and the moisture-proof / resistant property of the surface protective film, which is the outermost surface layer, may occur. Can not be expected to be polluted. The use of a film that has not been stretched can prevent the occurrence of cracks.

Since the surface protective film is a resin film whose inner surface is in contact with the organic polymer resin layer and is subjected to corona discharge treatment, (9) the adhesive force between the resin layer and the surface protective film can be enhanced.

Furthermore, since the photovoltaic element has a semiconductor photoactive layer as a light converting member and a transparent conductive layer formed on a conductive substrate, (10) a solar cell module having excellent flexibility. Can be That is, since the photovoltaic element itself is excellent in flexibility, a flexible solar cell module can be easily manufactured by using a flexible covering material together.

[0022]

FIG. 1 is a schematic structural view of a solar cell module according to the present invention. In FIG. 1, 101 is a photovoltaic element, 102 is a transparent encapsulant resin (organic polymer resin layer) on the surface, 103 is a transparent resin film located on the outermost surface (surface protection film), and 104 is Backside sealing material, 105
Is a backside coating film. Light from the outside enters through the transparent resin film 103 on the outermost surface, and the photovoltaic element 1
01, and the generated electromotive force is taken out from the output terminal (not shown).

Typical photovoltaic device 10 according to the present invention
No. 1 has a semiconductor photoactive layer as a light converting member and a transparent conductive layer formed on a conductive substrate. A schematic configuration diagram as an example thereof is shown in FIG.

In this figure, 201 is a conductive substrate, 20
2 is a back reflection layer, 203 is a semiconductor photoactive layer, 204 is a transparent conductive layer, 205 is a collector electrode, and 206a and 206b are output terminals.

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

The semiconductor photoactive layer 203 is a portion for performing photoelectric conversion. As a concrete material, pn junction type polycrystalline silicon, pin junction type amorphous silicon, or Cu is used.
InSe ₂ , CuInS ₂ , GaAs, CdS / Cu
₂ S, CdS / CdTe, CdS / InP, CdTe /
Examples thereof include compound semiconductors such as Cu ₂ Te. 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 CVD using silane gas or the like as a raw material, and in the case of compound semiconductor, Ion plating, ion beam deposition, vacuum deposition method, sputtering method, electrodeposition method and the like are available.

The transparent conductive layer 204 serves as the upper electrode of the solar cell. As a material to be used, for example, I
_{n 2 O 3, SnO 2,} In 2 O 3 -SnO 2 (ITO), Zn
There are O, TiO ₂ , Cd ₂ SnO ₄ , and a highly doped impurity-doped crystalline semiconductor layer. Examples of the forming method include resistance heating vapor deposition, sputtering method, spray method, CVD method, and impurity diffusion method.

On the transparent conductive layer 204, in order to collect current efficiently, a grid-shaped collecting electrode 205 (grid) is formed.
May be provided. Specific materials for the collector electrode 205 include, for example, Ti, Cr, Mo, W, Al, Ag, N.
Examples of the conductive paste include i, Cu, Sn, and silver paste. As a method of forming the collecting electrode 205, sputtering using a mask pattern, resistance heating, a CVD method, a method of depositing a metal film on the entire surface and then removing an unnecessary portion by etching, and patterning by a photo CVD directly There are a method of forming an electrode pattern, a method of plating after forming a negative pattern mask of a grid electrode pattern, a method of printing a conductive paste, and the like. The conductive paste is usually a fine powder of silver, gold, copper, nickel, carbon, etc. dispersed in a binder polymer. As the binder polymer, for example, polyester, epoxy,
Resins such as acrylic, alkyd, polyvinyl acetate, rubber, urethane, and phenol can be used.

Finally, in order to take out the electromotive force, the output terminal 2
06a and 206b are the conductive substrate 201 and the collecting electrode 205.
Attach to A method of spot welding or soldering a metal body such as a copper tab to the conductive substrate 201 is used, and a method of electrically connecting the metal body to the collector electrode 205 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 the desired voltage or current. Alternatively, a photovoltaic element can be integrated on an insulated substrate to obtain a desired voltage or current.

Next, the outermost transparent resin film 103 and the surface sealing material 102 used in the present invention will be described in detail below.

The surface sealing material 102 covers the irregularities of the photovoltaic element with a resin to protect the element from a harsh external environment such as temperature change, humidity and shock and to secure the adhesion between the surface film and the element. is necessary. Therefore, weather resistance, adhesiveness, filling properties, heat resistance, cold resistance, and impact resistance are required.
Examples of resins satisfying these requirements include ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), and polyolefin-based resins such as polyvinyl butyral resin. Resin, urethane resin, silicone resin, fluororesin, etc. may be mentioned. Among them, EVA has well-balanced physical properties for use in solar cells and is preferably used. However, since the heat distortion temperature is low as it is, it easily deforms or creeps under high temperature use. Therefore, it is desirable to increase the heat resistance by crosslinking. In the case of EVA, it is common to crosslink with an organic peroxide. Cross-linking with organic peroxide is a free radical generated from organic oxide, which abstracts hydrogen and halogen atoms in the resin to form C--C.
This is done by forming bonds. Known methods for activating organic peroxides include thermal decomposition, redox decomposition and ionic decomposition. Generally, the thermal decomposition method is preferred. Specific examples of the added amount of the organic peroxide include hydroperoxide, dialkyl (allyl) peroxide,
Examples include diacyl peroxides, peroxyketals, peroxyesters, peroxycarbonates and ketone peroxides. The amount of the organic peroxide added is 0.5 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the encapsulant resin.

By using the above organic peroxide in combination with the sealing material, it is possible to carry out crosslinking and thermocompression bonding under pressure and heating under vacuum. The heating temperature and time can be determined by the thermal decomposition temperature characteristics of each organic peroxide. Generally, the heating and pressurization is completed at a temperature and time at which thermal decomposition progresses by 90% or more, preferably 95% or more. To confirm the cross-linking of the encapsulant resin, the gel fraction may be measured, and in order to prevent the encapsulant resin from being deformed at a high temperature, it is desirable that the gel fraction be 70 wt% or more.

In order to carry out the above crosslinking reaction efficiently, triallyl isocyanurate (TAI) called a crosslinking assistant is used.
It is also possible to use C). Generally, sealing resin 1
The addition amount is 1 part by weight or more and 5 parts by weight or less with respect to 00 parts by weight.

The material of the encapsulant used in the present invention is excellent in weather resistance. However, in order to further improve the weather resistance or protect the lower layer of the encapsulant, a UV absorber should be used in combination. You can also A known compound is used as the ultraviolet absorber, but a low-volatile ultraviolet absorber is preferably used in consideration of the environment in which the solar cell module is used. Specifically, various salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based organic compounds can be mentioned.

If a light stabilizer is added at the same time as the ultraviolet absorber, the sealing material becomes more stable against light. A typical light stabilizer is a hindered amine light stabilizer.
The hindered amine-based light stabilizer does not absorb ultraviolet rays like the ultraviolet absorber, but when used in combination with the ultraviolet absorber, it shows a remarkable synergistic effect. Of course, there are substances other than the hindered amine type that function as a light stabilizer, but in many cases they are colored, which is not desirable for the sealing material of the present invention.

The amount of the ultraviolet absorber and the light stabilizer added is 0.1 to 1.0 wt.
%, 0.05 to 1.0 wt% is desirable.

Further, an antioxidant may be added to improve heat resistance and heat processability. The chemical structure of the antioxidant is monophenol type, bisphenol type,
There are high-molecular type phenol type, sulfur type and phosphoric acid type. The amount of antioxidant added is 0.05 to 1.0 w with respect to the encapsulant resin.
It is preferably t%.

When the solar cell module is expected to be used in a more severe environment, it is preferable to improve the adhesive force between the encapsulant resin and the photovoltaic element or the surface resin film. The adhesive strength can be improved by adding a silane coupling agent or an organic titanate compound to the sealing material. The amount of addition is preferably 0.1 parts by weight or more and 3 parts by weight or less with respect to 100 parts by weight of the sealing material resin, and is 0.25.
More preferably, it is 1 part by weight or more and 1 part by weight or less.

On the other hand, in order to suppress the decrease in the amount of light reaching the photovoltaic element as much as possible, the surface sealing material 102 must be transparent, and specifically, the light transmittance is 400 nm or more.
It is preferably 80% or more, and more preferably 90% or more in the visible light wavelength region of 00 nm or less. Further, in order to facilitate the incidence of light from the atmosphere, the refractive index at 25 degrees Celsius is preferably 1.1 to 2.0, and more preferably 1.1 to 1.6.

Surface resin film 10 used in the present invention
Since No. 3 is located on the outermost layer of the solar cell module, it is required to have performance such as weather resistance, stain resistance, and mechanical strength for ensuring long-term reliability of the solar cell module in outdoor exposure. Materials that are preferably used in the present invention include fluororesins and acrylic resins. Of these, fluororesins are preferred because they have excellent weather resistance and stain resistance. Specific examples include a polyvinylidene fluoride resin, a polyvinyl fluoride resin, and an ethylene tetrafluoride-ethylene copolymer. From the viewpoint of weather resistance, polyvinylidene fluoride resin is excellent, but tetrafluoroethylene-ethylene copolymer is excellent in terms of both weather resistance and mechanical strength and transparency.

The surface resin film 103 must be thick to some extent in order to secure mechanical strength, and is too thick from the viewpoint of cost. Specifically, it is preferably 20 μm or more and 200 μm or less, and more preferably 30 μm or more and 100 μm or less. Also,
This thickness is also a value at which the present invention can maximize the effect of preventing the occurrence of wrinkles in the film. That is, 20
If it is thinner than μm, wrinkles are likely to occur, and even if unevenness is provided as in the present invention, sufficient wrinkle removing effect cannot be exerted. If it is thicker than 200 μm, wrinkles are less likely to occur without unevenness, and the film is rigid. If there is, it becomes difficult to provide the unevenness.

In order to improve the adhesiveness between the surface resin film 103 and the sealing material 102, corona treatment,
It is desirable to perform surface treatment such as plasma treatment, ozone treatment, UV irradiation, electron beam irradiation, and flame treatment on one surface of the surface resin film 103. Among these, the corona discharge treatment is preferably used because the treatment speed is high and the adhesive strength can be greatly improved with a relatively simple device.

Surface resin film 103 and surface sealing material 1
The unevenness is formed on 02. The unevenness may be provided during the coating forming process or may be provided by a method such as pressing after the coating is formed. The shape of the unevenness is arbitrary, but the maximum height difference between the adjacent concave and convex portions is 5 μm or more 5
00 μm or less is preferable, and 10 μm or more and 300 μm or less is more preferable. In addition, the distance between adjacent concave portions and concave portions or adjacent convex portions and apexes of convex portions is preferably 0.1 mm or more and 10 mm or less, and more preferably 0.5 mm or more and 5 mm or less. If the maximum height difference between the adjacent concave portions and the convex portions is less than 5 μm, or if the distance between the adjacent concave portions and the concave portions or between the adjacent convex portions and the apexes of the convex portions exceeds 10 mm at the maximum, the effect of the present invention, especially the surface The adhesive strength between the resin film and the sealing resin cannot be sufficiently improved. FIG. 7 is a graph showing the relationship between the height difference of the unevenness and the adhesive force, and FIG. 8 is a graph showing the relationship between the distance between the vertices and the adhesive force. The ETFE film and the EVA which are both corona-treated.
Taking the adhesive strength with It will be clear with reference to this.

The maximum height difference between the concave and convex portions is 500 μ.
If it exceeds m, the surface resin film is excessively stretched, so that cracks may occur at the bottom of the recess even in a non-stretched film. On the other hand, when the distance between the adjacent concave portions and the concave portions or the adjacent convex portions and the apex of the convex portions is less than 0.1 mm at the maximum, the wrinkle removing effect of the surface resin film cannot be sufficiently exerted, and minute wrinkles are generated. Even if it enters, it stands out.

The cover film 105 on the back surface is necessary for maintaining electrical insulation between the conductive substrate of the photovoltaic element 101 and the outside. As a material, a material which can ensure sufficient electric insulation with a conductive substrate, has excellent long-term durability, and can withstand thermal expansion and thermal contraction and which is also flexible is preferable.
Examples of the film that is preferably used include nylon and polyethylene terephthalate.

The backside sealing material 104 is the photovoltaic element 101.
This is for the purpose of adhering the cover film 105 on the back surface with the cover film 105. As a material, a material which is capable of ensuring sufficient adhesiveness to a conductive substrate, has excellent long-term durability, and can withstand thermal expansion and thermal contraction, and which is also flexible, is preferable. Materials that are preferably used include hot-melt materials such as EVA and polyvinyl butyral, double-sided tapes, and flexible epoxy adhesives.

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

A reinforcing plate may be attached to the outside of the coating film on the back surface in order to increase the mechanical strength of the solar cell module or to prevent distortion and warpage due to temperature change. For example, steel plate, plastic plate, FRP
A (glass fiber reinforced plastic) plate is preferred.

A method of forming a solar cell module using the above-described photovoltaic element, encapsulant, front surface resin film and back surface coating film will be described below.

Surface sealing material 102 and surface resin film 10
In order to cover the light receiving surface of the photovoltaic element with No. 3, a method is generally used in which a sheet-shaped encapsulating material is prepared and is heat-pressed onto the element. That is, a solar cell module can be obtained by inserting the encapsulating material sheet between the photovoltaic element 101 and the surface resin film 103 and thermocompression bonding. At this time, if a sheet-shaped member having an uneven shape is arranged on the outside of the surface resin film and is pressed against the surface resin film during pressure bonding, the unevenness can be easily provided on the surface of the covering material. The heating temperature and the heating time during pressure bonding are determined by the temperature and time for the crosslinking reaction to proceed sufficiently. As the method of thermocompression bonding, various conventionally known methods such as vacuum lamination and roll lamination can be selected and used.

As the sheet-like member having the uneven shape, aluminum mesh, stainless mesh,
Any of glass fiber nonwoven fabric, glass fiber woven fabric, organic resin fiber nonwoven fabric, organic resin fiber woven fabric, and the like are preferably used.

The back surface may be coated with the back surface coating film and the back surface sealing material in the same manner. Usually, the front surface encapsulating material and the back surface encapsulating material are the same material, so that they can be performed simultaneously with the above steps.

[0054]

EXAMPLES The present invention will be described in detail below based on examples.

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

On the cleaned stainless steel substrate 201, an Al layer (film thickness 5000) was formed as the back surface reflection layer 202 by the sputtering method.
Å) and a ZnO layer (film thickness 5000 Å) are sequentially formed. Then, by plasma CVD method, SiH ₄ , PH ₃ and H ₂
An i-type a-Si layer from a mixed gas of SiH ₄ and H ₂ , a p-type microcrystalline μc-Si layer from a mixed gas of SiH ₄ , BF ₃ and H _2. Formed, and the thickness of the n-layer is 150Å / the thickness of the i-layer 4000Å / the thickness of the p-layer 100Å / n
Layer thickness 100Å / i layer thickness 800Å / p layer thickness 100Å
A tandem-type a-Si semiconductor photoactive layer 203 having the above layer structure was formed. Next, as a transparent conductive layer 204, an In ₂ O ₃ thin film (film thickness 700 Å) was formed by vapor deposition of In in an O ₂ atmosphere by a resistance heating method. Further, a grid electrode 205 for current collection is formed by screen printing of a silver paste, and finally a copper tab is attached as a negative side terminal 206b to a stainless steel substrate using a stainless solder 208, and a tin foil tape is used as a positive side terminal 206a. A photovoltaic element was obtained by attaching the conductive adhesive 207 to the collecting electrode 205 to form an output terminal. The positive terminal was turned to the back surface via an insulator so that the output could be taken out from the hole of the back surface coating material described later.

[Modularization] A method for producing a solar cell module by coating the photovoltaic element will be described with reference to FIG.

EVA sheet 3 is provided on the light receiving surface side of the cell block.
02 (Springborn Laboratories, trade name Photocap, thickness 460 μm) and unstretched ETFE film 303 with corona discharge treatment on one side
(Dupont, Tefzel film, thickness 50
Micrometer), EVA sheet 304 (made by Springborn Laboratories, product name Photocap, thickness 460 μm) and nylon film 305 (made by DuPont, product name Dartec, thickness 6) on the back side.
3.5 micrometer) and galvalume steel plate 306
(Galvanized steel sheet, thickness 0.27mm) ETFE30
3 / EVA 302 / cell block / EVA 304a / nylon 305 / EVA 304b / steel plate 306 in this order. At this time, EVA protruding outside the ETFE
Release Teflon film 307 (manufactured by DuPont, trade name Teflon PFA film, thickness 50 μm) through aluminum mesh 308 (16
× 18 mesh, wire diameter 0.011 inch) was arranged.
The laminated body was heated at 150 ° C. for 30 minutes while being degassed under pressure using a vacuum laminating apparatus to obtain a solar cell module having a surface having irregularities formed by an aluminum mesh. This solar cell module is shown in FIG.
Reference numeral 401 is a photovoltaic element, 402 is a surface sealing material, 403 is a surface resin film, 404 is a back surface covering film, and 406.
Is a steel plate. The EVA sheet used here is widely used as a sealing material for solar cells.
1.5 parts by weight of a cross-linking agent, 0.3 parts by weight of an ultraviolet absorber, relative to 100 parts by weight of a VA resin (vinyl acetate content 33%)
0.1 parts by weight of a light stabilizer, 0.2 parts by weight of an antioxidant, and 0.25 parts by weight of a silane coupling agent are mixed. The output terminal was previously turned to the back surface of the photovoltaic element, and after lamination, the output could be taken out from the terminal take-out ports 408a and 408b previously opened in the galvalume steel plate 406.

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

Example 2 A solar cell module was prepared in the same manner as in Example 1 except that the aluminum mesh used for forming the irregularities was changed to a stainless steel mesh of 16 × 16 mesh (wire diameter 0.27 mm). Was produced.

Example 3 A solar cell module was prepared in the same manner as in Example 1 except that the aluminum mesh used for forming the irregularities was changed to the stainless steel mesh of 20 × 20 mesh (wire diameter 0.21 mm). did.

(Example 4) A solar cell module was prepared in the same manner as in Example 1 except that the aluminum mesh used for forming the irregularities was changed to a stainless steel mesh of 40 × 40 mesh (wire diameter 0.15 mm). It was made.

(Example 5) Instead of the aluminum mesh used for forming the unevenness in Example 1, an organic fiber nonwoven fabric having a mesh-like embossed surface (Asahi Kasei Co., Ltd., trade name Eltus, product number) A solar cell module was produced in the same manner except that E05030) was used.

Example 6 A solar cell module was manufactured in the same manner as in Example 1 except that the ETFE film was changed to have a thickness of 25 μm.

Example 7 A solar cell module was prepared in the same manner as in Example 1, except that the ETFE film was replaced with an acrylic resin film (trade name: acryprene, manufactured by Mitsubishi Rayon Co., Ltd., thickness: 50 μm).

Comparative Example 1 A solar cell module having a smooth surface was manufactured without using the aluminum mesh used for forming the unevenness in Example 1.

(Comparative Example 2) A solar cell module having a smooth surface was prepared without using the aluminum mesh used for forming the irregularities in Example 6.

Comparative Example 3 A solar cell module having a smooth surface was manufactured without using the aluminum mesh used for forming the unevenness in Example 7.

The following items were evaluated for the solar cell modules produced in the above-mentioned Examples and Comparative Examples.
The results are shown in Table 1.

(1) Concavo-convex shape The concavo-convex shape of the module surface was measured using a contact-type surface roughness meter (manufactured by Tenker Instruments Co., device name Alphastep), and the maximum height difference between the adjacent concave and convex portions was measured. When,
The maximum distance between adjacent concave portions and concave portions or adjacent convex portions and apexes of convex portions was determined.

(2) Diffuse reflectance Integrating sphere type reflection spectrophotometer (Hitachi, device name U-400)
0) was used to determine the ratio of the total reflected light to the diffused reflected light on the module surface. The table shows the ratio of diffuse reflection light when the total reflection light is 100.

(3) Adhesive Strength The adhesive strength between the surface film of the module and the sealing material resin was measured. That is, a sample is cut out from the module and subjected to a 180 degree peeling test (atmosphere: normal temperature, peeling speed: 50
(mm / min), the adhesive force between the film and the resin in a width of 25 mm was measured, and the average of 5 samples was obtained.

(4) Initial appearance The appearance of the module surface immediately after fabrication was observed. Those without defects were marked with ○, and those with defects were briefly commented on the situation.

(5) Temperature Cycle A temperature cycle test of −40 ° C./1 hour and 90 ° C./1 hour was conducted for 50 cycles, and the change in appearance of the solar cell module after the test was observed. Those that did not change were marked with a circle, and those that did change, simply commented on the situation.

(6) 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 that did not change were marked with a circle, and those that did change, simply commented on the situation.

[0076]

[Table 1] As is clear from Table 1, no problems were observed in the solar cell module of the example in any of the initial appearance, temperature cycle test, and temperature / humidity cycle test. Further, the proportions of diffusely reflected light are all higher than in the comparative example, and the adhesive force between the surface resin film and the sealing material resin is stronger than in the comparative example using the same surface resin film.

On the other hand, in the comparative example, wrinkles were observed on the surface film in the temperature cycle test and the temperature / humidity cycle test. Further, in Comparative Example 2, since a thin film was used, wrinkles were formed at the time of coating formation, and the initial appearance was poor.

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

[0079]

According to the present invention, at least the transparent organic polymer resin layer provided on the light-incident side surface of the photovoltaic element and the transparent surface protective film located on the outermost surface in contact therewith. In a solar cell module coated with a coating material including two or more layers, the coating material surface has irregularities, and the maximum height difference between adjacent concave portions and convex portions is 5 μm or more and 500 μm or less. By setting the distance between adjacent concave portions and concave portions or adjacent convex portions and apexes of the convex portions to a maximum of 0.1 mm or more and 10 mm or less, direct reflection light on the surface is small, and the surface film and the sealing organic material are small. Good adhesion with resin, wrinkles are not easily formed on the surface film during coating formation, and there is no peeling of the film or wrinkles even after long-term outdoor exposure. It is possible to provide a solar cell module.

[Brief description of drawings]

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

2A and 2B are an example of a schematic cross-sectional view (a) and a light-receiving surface side top view (b) showing a basic configuration of a photovoltaic element used in the solar cell module of FIG.

FIG. 3 is a schematic cross-sectional view of a laminated body when the solar cell module of Example 1 is modularized.

FIG. 4 is a schematic cross-sectional view of the solar cell module of Example 1.

FIG. 5 is a schematic diagram showing a light trace of sunlight when a solar cell module having a smooth surface is installed on a roof.

FIG. 6 is a schematic diagram showing a light trace of sunlight when the solar cell module according to the present invention is installed on a roof.

FIG. 7 is a graph showing the relationship between the height difference of unevenness and the adhesive force.

FIG. 8 is a graph showing the relationship between the distance between vertices and the adhesive force.

FIG. 9 is a schematic cross-sectional view showing an example of a conventional solar cell module.

[Explanation of symbols]

101, 301, 401, 901 Photovoltaic device, 102, 302, 402 Surface sealing material (organic polymer resin layer), 103, 303, 403, 902 Surface resin film (surface protection film), 104, 304, 404 Backside sealing material, 105, 305, 405 backside coating film, 201 conductive substrate, 202 backside reflective layer, 203 semiconductor photoactive layer, 204 transparent conductive layer, 205 current collecting electrode, 206, 407 terminal, 207 conductive paste, 208 solder, 306, 406 steel plate, 408a, 408b terminal extraction port, 903 filler, 904 insulator.

Front Page Continuation (72) Inventor Satoshi Yamada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (22)

[Claims] 1. At least two layers of a transparent organic polymer resin layer provided on the light-incident side surface of a photovoltaic element and a transparent surface protective film which is in contact with the surface and is located on the outermost surface thereof. In a solar cell module coated with a coating material containing, an unevenness is formed on the surface of the coating material, the maximum difference in height between adjacent concave portions and convex portions is 5 μm or more and 500 μm or less, and adjacent concave portions and concave portions or The solar cell module is characterized in that the maximum distance between adjacent protrusions is 0.1 mm or more and 10 mm or less. 2. The thickness of the surface protective film is 20 μm
The solar cell module according to claim 1, wherein the thickness is 200 μm or less. 3. The surface protective film is an acrylic resin,
The solar cell module according to claim 1 or 2, comprising a resin selected from among fluoride polymers. 4. The solar cell module according to claim 3, wherein the fluoride polymer is a tetrafluoroethylene-ethylene copolymer. 5. The solar cell module according to claim 1, wherein the surface protection film is a resin film that has not been stretched. 6. The solar cell module according to claim 1, wherein the surface protection film is a resin film whose surface in contact with the organic polymer resin layer on the inside is subjected to corona discharge treatment. . 7. The transparent organic polymer resin layer is mainly composed of a resin selected from polyvinyl butyral and ethylene-vinyl acetate copolymer (EVA). The solar cell module according to any one of items. 8. The photovoltaic element according to claim 1, wherein the photovoltaic element has a semiconductor photoactive layer as a light converting member and a transparent conductive layer on a conductive substrate. Solar cell module. 9. The solar cell module according to claim 8, wherein the semiconductor photoactive layer is an amorphous semiconductor thin film. 10. The solar cell module according to claim 9, wherein the amorphous semiconductor thin film is amorphous silicon. 11. A transparent organic polymer resin layer provided on the light-incident side surface of a photovoltaic element, and at least two layers of a transparent surface protective film in contact with the transparent organic polymer resin layer and located on the outermost surface thereof. In the method for manufacturing a solar cell module coated with a coating material, at least the organic polymer resin layer and the surface protection film are arranged on the light incident side surface of the photovoltaic element, and further on the outside thereof, unevenness is formed on the surface. After arranging a sheet-shaped member having a shape such that the uneven side faces the surface protection film, the photovoltaic element is coated by a thermocompression bonding method, and at the same time, unevenness is formed on the surface of the coating material on the light incident side surface. A method for manufacturing a solar cell module, comprising: 12. The unevenness on the surface of the coating material is such that the maximum height difference between adjacent concave portions and convex portions is 5 μm or more and 500 μm or less, and the distance between adjacent concave portions and concave portions or adjacent convex portions and apexes of convex portions. Is 0.1 mm or more and 10 mm or less at the maximum, The method for manufacturing a solar cell module according to claim 11, wherein. 13. The sheet-shaped member having an uneven shape on the surface is an aluminum mesh, a stainless mesh,
The method for manufacturing a solar cell module according to claim 11 or 12, wherein the glass fiber nonwoven fabric, the glass fiber woven fabric, the organic resin fiber nonwoven fabric, or the organic resin fiber woven fabric is selected. 14. The surface protection film has a thickness of 20 μm.
m or more and 200 μm or less.
14. The method for manufacturing the solar cell module according to any one of 1 to 13. 15. The method for manufacturing a solar cell module according to claim 11, wherein the surface protection film is made of a resin selected from acrylic resins and fluoride polymers. . 16. The fluoropolymer is a tetrafluoroethylene-ethylene copolymer.
5. The method for manufacturing the solar cell module according to item 5. 17. The surface protection film is a resin film which has not been stretched.
17. The method for manufacturing the solar cell module according to any one of 1 to 16. 18. The solar cell module according to claim 11, wherein the surface protection film is a resin film whose surface in contact with the organic polymer resin layer on the inside is subjected to corona discharge treatment. Manufacturing method. 19. The transparent organic polymer resin layer is mainly composed of a resin selected from polyvinyl butyral and ethylene-vinyl acetate copolymer (EVA). A method for manufacturing the solar cell module according to any one of 1. 20. The photovoltaic element according to claim 11, wherein a semiconductor photoactive layer as a light converting member and a transparent conductive layer are formed on a conductive substrate. A method for manufacturing a solar cell module according to item. 21. The method of manufacturing a solar cell module according to claim 20, wherein the semiconductor photoactive layer is an amorphous semiconductor film. 22. The method of manufacturing a solar cell module according to claim 21, wherein the amorphous semiconductor thin film is amorphous silicon.