DE102008043707A1 - Production of solar cell modules - Google Patents

Abstract

Use of a) at least one polyalkyl (meth) acrylate and b) at least one compound of the general formula of the formula (I) in which R is an optionally substituted alkyl, cycloalkyl, aralkyl or aryl radical and the ring A may have further substituents, for the production of solar cell modules, in particular for the production of light concentrators for solar cell modules.

Description

The The present invention relates to the manufacture of solar cell modules and the corresponding solar cell modules.

STATE OF THE ART

A Solar cell or photovoltaic cell is an electrical component, this is the radiation energy contained in the light, especially in sunlight converted directly into electrical energy. The physical basis The transformation is the photovoltaic effect, which is a special case of the internal photoelectric effect.

3 is a schematic cross section showing the basic structure of a solar cell module. In 3 designated 501 a photovoltaic element, 502 a solidifying agent, 503 a slice and 504 a back wall. Sunlight radiates on the photosensitive surface of the photovoltaic element 501 one by holding the disc 503 and the solidifying agent 502 penetrates, and is converted into electrical energy. The generated current is output from output terminals (not shown).

The photovoltaic element can not extreme external conditions endure because it is easily corroded and very fragile. It must therefore be covered and protected by a suitable material become. In most cases, this is achieved by: one the photovoltaic element using a suitable Solidifying agent between a transparent pane with weather resistance, such as As a glass sheet, and a rear wall with excellent Moisture resistance and high electrical Insert resistance and laminate.

When Solidifying agents for solar cells become common Polyvinyl butyral and ethylene-vinyl acetate copolymers (EVA) are used. In particular, crosslinkable EVA compositions show excellent Properties, such as good heat resistance, a high weather resistance, a great Transparency and good cost efficiency.

The Solar cell module should have a high resistance, because it used to be outside for a long time shall be. Consequently, the solidifying agent u. a. a excellent weather resistance and high heat resistance exhibit. However, often a light-induced and / or thermally-induced degradation of the solidifying agent and as a result its a yellow discoloration of the solidifying agent and / or observed a peeling off of the photovoltaic element, if the module for a long time, such. Ten years, is used outside. The yellow discoloration of the Solidifying agent leads to a decrease in usable Proportion of incident light and therefore to a lesser electrical power. On the other hand, allows peeling from the photovoltaic element, the penetration of moisture, which to corrosion of the photovoltaic element itself or metallic Parts in the solar cell module can lead and also one Deterioration of the solar cell module performance has.

Even though the commonly used EVAs per se are good solidifiers are gradually degraded by hydrolysis and / or pyrolysis. Over time, heat or moisture causes acetic acid released. This leads to a yellow discoloration of the solidifying agent, to a decrease in mechanical strength and a decrease in the adhesion strength of the solidifying agent. Furthermore, the liberated acetic acid acts as a catalyst and additionally speeds up the mining. About that In addition, the problem arises that the photovoltaic element and / or other metal parts in the solar cell module by the acetic acid be corroded.

To solve these problems suggests the European patent application EP 1 065 731 A2 the use of a solar cell module comprising a photovoltaic element and a polymeric solidifying agent, wherein the polymeric solidifying agent is an ethylene-acrylic ester-acrylic acid terpolymer, an ethylene-acrylic ester-maleic anhydride terpolymer, an ethylene-methacrylic ester-acrylic ester terpolymer, an ethylene- Acrylic ester-methacrylic acid terpolymer, an ethylene-methacrylic ester-methacrylic acid terpolymer and / or an ethylene-methacrylic ester-maleic anhydride terpolymer should contain. However, both the weatherability and the effectiveness of such solar cell modules is limited.

Out the state of the art is also the improvement of the weather resistance of acrylic molding compounds by the use of suitable UV absorbers known.

als UV-Absorber für Polymere. Der Rest soll in m- oder p-Stellung zur bereits vorhandenen Gruppe am Ring A angeordnet sein. Weiterhin kann der Ring A durch ein oder mehrere Halogenatome, Alkyl- oder Methoxygruppen substituiert sein. Der Rest R steht für einen gegebenenfalls substituierten Alkyl-, Cycloalkyl-, Aralkyl- oder Arylrest.This is what the German patent teaches DE 18 01 221 B1 the use of compounds of the formula (I)

as a UV absorber for polymers. The remainder should be arranged in the m- or p-position to the already existing group on the ring A. Furthermore, ring A may be substituted by one or more halogen atoms, alkyl or methoxy groups. The radical R is an optionally substituted alkyl, cycloalkyl, aralkyl or aryl radical.

Of the Use in polyacrylates is mentioned as a possibility. Notes on the use of the molding compositions for the production of solar cell modules, the publication can not be found.

WO 2008/025738 describes the use of a composition containing two UV absorbers, for the protection of organic substrates, in particular organic polymers, against degradation due to environmental influences, such as. B. yellowing, loss of transparency and gloss reduction. Benzylidenebismalonate of the above formula (I), in particular Hostavin ^® B-CAP, a para-substituted Benzylidenbismalonat of formula (I) without further substituents with R = ethyl, are used in this context as a UV absorber.

Of the Use of the composition for ethylene alkyl acrylate copolymers, Ethylene alkyl methacrylate copolymers and ethylene acrylic acid copolymers is mentioned as a possibility. Notes on the use of the molding compositions for the production of solar cell modules However, the document can not be found.

US 6,433,044 B1 discloses a methyl methacrylate resin composition comprising methyl methacrylate resin and a 2- (1-arylalkylidene) malonic acid ester in an amount ranging from 0.0005 to 0.1 part by weight per 100 parts by weight of methyl methacrylate resin.

The Resin composition is intended in particular for the production be used by optical fibers. Indications of a use of Molding compositions for the production of solar cell modules are However, the publication can not be found.

JP 2005-298748 A provides molded parts of methacrylic resin which preferably comprises 100 parts by weight of methacrylic resin comprising 60-100% by weight of meth-methacrylate units and 0-40% by weight of other copolymerizable vinyl monomer units, and 0.005-0.15% by weight of 2- (2-hydroxy-4-n-octyloxyphenyl) -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine and / or 2-hydroxy-4-octyloxybenzophenone. The moldings are said to have a marked barrier to UV rays and to exhibit a transparency of at most 20% at 340 nm and a transparency of at least 70% at 380 nm, measured on moldings having a thickness in the range of 0.5 to 5 mm.

The Moldings are to be used in particular as lighting covers become. Notes on a use of the moldings for the Production of solar cell modules are the publication, however not to be taken.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention, possibilities for reducing the power loss of a solar cell during long-term use outdoors, especially at high temperature and / or high humidity, show. For this purpose, in particular, ways were sought excellent weather resistance, one possible high heat resistance and one possible great light transmission as well as possible to achieve low water absorption. Furthermore, one was possible low release of corrosion-promoting substances, especially acids, and as strong as possible Adhesion to the various basic elements of a solar cell module desired.

These and other non-specific tasks, which arise from the contexts discussed in the near but obvious manner, by the use of a molding compound with al len features of the present claim 1 solved. The dependent claims on claim 1 describe particularly useful variants of the invention. Furthermore, the corresponding solar cell modules are placed under protection.

• a) mindestens ein Polyalkyl(meth)acrylat und
• b) mindestens eine Verbindung der allgemeinen Formel der Formel (I)
  
  in der R für einen gegebenenfalls substituierten Alkyl-, Cycloalkyl-, Aralkyl- oder Arylrest steht und der Ring A weitere Substituenten aufweisen kann, zur Herstellung von Solarzellenmodulen, insbesondere zur Herstellung von Lichtkonzentratoren für Solarzellenmodule, einsetzt, gelingt es auf nicht ohne weiteres vorhersehbare Weise, einen Leistungsabfall einer Solarzelle bei Langzeitnutzung im Freien, insbesondere bei hoher Temperatur und/oder hoher Luftfeuchtigkeit, bestmöglich zu verhindern. Insbesondere wird eine exzellente Witterungsbeständigkeit, eine sehr hohe Wärmebeständigkeit und eine sehr große Lichtdurchlässigkeit sowie eine überaus geringe Wasserabsorption erreicht. Weiterhin werden auch bei Langzeitnutzung im Freien keine Korrosions-fördernden Substanzen freigesetzt und es wird eine sehr starke Adhäsion an den verschiedenen Grundelementen eines Solarzellenmoduls erreicht.

By doing that

• a) at least one polyalkyl (meth) acrylate and
• b) at least one compound of the general formula of the formula (I)
  
  in which R is an optionally substituted alkyl, cycloalkyl, aralkyl or aryl radical and the ring A may have further substituents used for the production of solar cell modules, in particular for the production of Lichtkonzentratoren for solar cell modules, it succeeds in not easily foreseeable manner To prevent the best possible performance degradation of a solar cell during long-term use outdoors, especially at high temperature and / or high humidity. In particular, excellent weatherability, very high heat resistance, and very high light transmittance, and extremely low water absorption are achieved. Furthermore, no corrosion-promoting substances are released even in long-term outdoor use and it is achieved a very strong adhesion to the various basic elements of a solar cell module.

The The solution presented here allows efficient use of "usable" light in the visible wavelength range. At the same time, other wavelength ranges, in particular in the UV range, which are not used to generate electricity can, effectively absorbed. This absorption will increases the weather resistance of the solar cell modules. Furthermore, the absorption becomes a disadvantageous effect Heating the light collectors is prevented without any cooling elements must be used for these purposes Life of the solar cell modules is extended and their Overall performance and effectiveness is increased.

The procedure according to the invention gives rise in particular to the following advantages:
A solar cell module having excellent weather resistance, heat resistance and moisture resistance is made available. No peeling occurs even if the module is exposed to outdoor conditions for a long time. Furthermore, the weather resistance is improved because no acid is released even at high temperatures and high humidity. Since no corrosion of the photovoltaic element by acid occurs, stable long-term performance of the solar cell is maintained.

Farther materials are used whose weather resistance, Heat resistance and moisture resistance outstanding are and which have an excellent light transmission, which enables the production of very good solar cell modules.

DESCRIPTION OF THE DRAWINGS

1 is a schematic cross-section of a preferred solar cell module according to the present invention.

2a and 2 B are schematic cross-sections showing the basic structure of a photovoltaic element, which in the solar cell module 1 is preferably used, or a plan view of the photosensitive surface of the photovoltaic element.

3 is a schematic cross section of a conventional solar cell.

1

101

photovoltaic element

102

solidifying agent

103

disc

104

solidifying agent

105

rear wall

2a

201

conducting substratum

202

reflective layer

203

photoactive Semiconductor layer

204

transparent conductive layer

205

collecting electrode

206a

Alligator Clip

206b

Alligator Clip

207

senior, adhesive paste

208

senior Paste or solder

2 B

201

conducting substratum

202

reflective layer

203

photoactive Semiconductor layer

204

transparent conductive layer

205

collecting electrode

206a

Alligator Clip

206b

Alligator Clip

207

senior, adhesive pastes

3

501

photovoltaic element

502

solidifying agent

503

disc

504

rear wall

DETAILED DESCRIPTION THE INVENTION

• a) mindestens ein Polyalkyl(meth)acrylat und
• b) mindestens eine Verbindung der allgemeinen Formel der Formel (I) zur Herstellung von Solarzellenmodulen eingesetzt. Dabei können diese Komponenten gemeinsam in einer Zusammensetzung, z. B. in Mischung in einer Formmasse, zur Herstellung eines gemeinsamen Elements, wie z. B. eines Formteils, des Solarzellenmoduls verwendet werden. Es ist aber auch möglich, dass sie jeweils separat für die Herstellung von verschiedenen Einzelelementen eines Solarzellenmoduls eingesetzt werden.

Within the scope of the present invention

• a) at least one polyalkyl (meth) acrylate and
• b) at least one compound of the general formula of the formula (I) used for the production of solar cell modules. These components may together in a composition, for. B. in a mixture in a molding composition, for producing a common element, such as. As a molding, the solar cell module can be used. But it is also possible that they are each used separately for the production of various individual elements of a solar cell module.

The Polyalkyl (meth) acrylate can be used individually or in a mixture of several various polyalkyl (meth) acrylates are used. Furthermore For example, the polyalkyl (meth) acrylate may also be in the form of a copolymer.

In the context of the present invention, homopolymers and copolymers of C ₁ -C ₁₈ -alkyl (meth) acrylates, suitably of C ₁ -C ₁₀ -alkyl (meth) acrylates, in particular of C ₁ -C ₄ -alkyl (meth) acrylate polymers which may optionally still contain different monomer units, particularly preferred.

The notation (meth) acrylate here means both methacrylate, such as. As methyl methacrylate, ethyl methacrylate, etc., as well as acrylate, such as. As methyl acrylate, ethyl acrylate, etc., as well as mixtures of the two Monomers.

The use of copolymers containing 70 wt .-% to 99 wt .-%, in particular 70 wt .-% to 90 wt .-%, C ₁ -C ₁₀ alkyl (meth) acrylates, has proven particularly useful. Preferred C ₁ -C ₁₀ alkyl methacrylates include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, isooctyl methacrylate and ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, and cycloalkyl methacrylates such as cyclohexyl methacrylate. Isobornyl methacrylate or Ethylcyclohexlmethacrylat. Preferred C ₁ -C ₁₀ -alkyl acrylates include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, ocyl acrylate, isooctyl acrylate, nonyl acrylate, decyl acrylate and ethylhexyl acrylate and cycloalkyl acrylates such as cyclohexyl acrylate, Isobornyl acrylate or Ethycyclohexlacrylat.

Very particularly preferred copolymers comprise from 80% to 99% by weight of methyl methacrylate (MMA) units and from 1% to 20%, preferably from 1% to 5%, by weight, C ₁ C ₁₀ -alkyl acrylate units, in particular methyl acrylate, ethyl acrylate, and / or butyl acrylate units. The use of the polymethyl methacrylate available from Rohm GmbH PLEXIGLAS ^® 7N has proven itself in this context in particular.

The polyalkyl (meth) acrylate can be prepared by polymerization methods known per se, free radical polymerization processes, in particular, bulk, solution, suspension and emulsion polymerization processes being particularly preferred. Initiators particularly suitable for this purpose include in particular azo compounds, such as 2,2'-azobis (isobutyronitrile) or 2,2'-azobis (2,4-dimethylvaleronitrile), redox systems, such as the combination of tertiary amines with peroxides or Sodium disulfite and persulfates of potassium, sodium or ammonium or preferably peroxides (see, for example, H. Rauch-Puntigam, Th. Völker, "Acrylic and Methacrylic Compounds", Springer, Heidelberg, 1967 or Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 1, p. 386 et seq., J. Wiley, New York, 1978 ). Examples of particularly suitable peroxide polymerization initiators are dilauroyl peroxide, tert-butyl peroctoate, tert-butyl perisononanoate, dicyclohexyl peroxydicarbonate, dibenzoyl peroxide and 2,2-bis (tert-butylperoxy) betaine. It is also possible with preference to carry out the polymerization with a mixture of different polymerization initiators having a different half-life, for example dilauroyl peroxide and 2,2-bis (tert-butylperoxy) butane, in order to keep the radical stream constant during the polymerization and at different polymerization temperatures. The amounts of polymerization initiator used are generally from 0.01% by weight to 2% by weight, based on the monomer mixture.

The Polymerization can be both continuous and batchwise be performed. After the polymerization, the polymer is over conventional isolation and separation steps, such. B. filtration, Coagulation and spray drying, won.

The adjustment of the chain lengths of the polymers or copolymers can be carried out by polymerization of the monomer or monomer mixture in the presence of molecular weight regulators, in particular of the known mercaptans, for example n-butylmercaptan, n-dodecylmercaptan, 2-mercaptoethanol or 2-ethylhexyl thioglycolate, pentaerythritol tetrathioglycolate; wherein the molecular weight regulator generally in amounts of 0.05 wt .-% to 5 wt .-% based on the monomer or monomer mixture, preferably in amounts of 0.1 wt .-% to 2 wt .-% and particularly preferably in amounts from 0.2 wt .-% to 1 wt .-%, based on the monomer or monomer mixture, can be used (see, for example H. Rauch-Puntigam, Th. Völker, "Acrylic and Methacrylic Compounds", Springer, Heidelberg, 1967 ; Houben-Weyl, Methods of Organic Chemistry, Rd. XIV / 1, page 66, Georg Thieme, Heidelberg, 1961 or Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 1, pp. 296 et seq., J. Wiley, New York, 1978 ). Particular preference is given to using n-dodecylmercaptan as molecular weight regulator.

in der R für einen gegebenenfalls substituierten Alkyl-, Cycloalkyl-, Aralkyl- oder Arylrest steht und der Ring A weitere Substituenten aufweisen kann.In the context of the present invention, at least one compound of the general formula of the formula (I) is furthermore used to prepare the solar cell modules

in which R is an optionally substituted alkyl, cycloalkyl, aralkyl or aryl radical and the ring A may have further substituents.

The Residues R can be the same or different.

suitable Radicals R are in particular methyl, ethyl, propyl, dodecyl, cyclohexyl, Benzyl, phenyl and optionally halogen, alkyl and alkoxy substituted phenyl radicals. Especially preferred are alkyl groups having 1 to 18 carbon atoms and cycloalkyl groups 1 to 18 carbon atoms, in particular radicals having 1 to 8 carbon atoms, preferably with 1 to 4 carbon atoms, especially methyl groups and ethyl groups. Ethyl groups are most preferred.

suitable Substituents for A are, for example, halogen or alkyl. Within the scope of a particularly preferred variant of the invention the ring no further substituents except hydrogen on.

und der Formel (III)

worin die Reste R' die gleiche Bedeutung wie zuvor besitzen und vorzugsweise für einen nicht weiter substituierten Alkylrest mit 1-20 Kohlenstoffatomen, einen Cyclohexyl-, Benzyl- oder Phenylrest stehen. Besonders bevorzugt werden Verbindungen der Formel (II), worin R', jeweils unabhängig voneinander, für Ethyl, n-Dodecyl, Cyclohexyl, Benzyl oder Phenyl, insbesondere für Ethyl, steht.Preferred compounds of the framework of the formula (I) are those of the formula (II)

and the formula (III)

wherein the radicals R 'have the same meaning as before and preferably represent a no further substituted alkyl radical having 1-20 carbon atoms, a cyclohexyl, benzyl or phenyl radical. Particular preference is given to compounds of the formula (II) in which R ', in each case independently of one another, is ethyl, n-dodecyl, cyclohexyl, benzyl or phenyl, in particular ethyl.

worin der Ring A gegebenenfalls weitere Substituenten aufweisen kann, mit Malonsäureestern der Formel (V)

erhalten.The compounds of the formula (I) can be prepared, for example, by condensation of dialdehydes of the formula (IV)

wherein the ring A may optionally have further substituents, with malonic esters of the formula (V)

receive.

suitable Aldehydes of the formula (IV) are in particular terephthalaldehyde, isophthalaldehyde, 2-chloroterephthalaldehyde, 2-fluoroterephthalaldehyde, 2-methylterephthalaldehyde, 2,2-dichloroterephthalaldehyde, 2,5-dichloroterephthalaldehyde, 2,5-diethylterephthalaldehyde, Tetramethylterephthalaldehyde, 2,5-dimethoxyterephthalaldehyde, 4-methoxyisophthalaldehyde, 5-methylisophthalaldehyde and tetramethylisophthalaldehyde.

Suitable malonic esters of the formula (V) are in particular diethyl malonate, dodecyl malonate, dicyclohexyl malonate, dibenzyl malonate, diphenyl malonate, dimethyl malonate, methyl malonate, diethyl malonate, methyl malonate, Malonic acid dipropyl ester, malonic acid di (3-chloropropyl) ester, diisopropyl malonate, dibutyl malonate, diisobutyl malonate, diisobutyl malonate, diisobutyl malonate, malonic acid dipentylate, diisobutyl malonate, dioctyl malonic acid ester, malonyl dinonylate, dodecyl malonic acid ester, dodecyl malonate, malonic acid dioctadecyl ester and methyl malonate.

in the Under the present invention, it may be helpful to the Specialist well-known tools additionally use. Preference is given to external lubricants, antioxidants, flame retardants, other UV stabilizers, flow aids, metal additives for shielding electromagnetic radiation, antistatic agents, mold release agents, Dyes, pigments, adhesion promoters, weathering agents, Plasticizers, fillers and the like.

in the Within a particularly preferred embodiment of the present invention is at least one sterically hindered Amine used, thereby further improving the weather resistance is improved. A yellow discoloration or a degradation of the Materials that have long been exposed to outdoor conditions can be further reduced.

Especially preferred hindered amines include dimethyl succinate 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperazine 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-triazinkondensat, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate and 2- (3,5-di-t-4-hydroxybenzyl) -2-n-butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl).

Farther has the use of silane coupling agents or organic titanium compound especially proven, whereby the adhesion to inorganic materials is further improved.

suitable Silane coupling agents include vinyl trichlorosilane, vinyl tris (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 and γ-chloropropyltrimethoxysilane.

The relative proportions of the polyalkyl (meth) acrylate and the compound of general formula (I) can in principle be chosen freely become.

• a) 90 Gew.-% bis 99,99 Gew.-% Polyalkyl(meth)acrylats und
• b) 0,01 Gew.-% bis 0,4 Gew.-% Verbindung der allgemeinen Formel (I).

Appropriately, they are present in a common molding material. Particularly preferred molding compositions comprise, in each case based on their total weight,

• a) 90 wt .-% to 99.99 wt .-% polyalkyl (meth) acrylate and
• b) 0.01 wt .-% to 0.4 wt .-% compound of general formula (I).

The Incorporation of the compounds into a common molding material can carried out by the literature methods, for example by Blending with the polymer before further processing at higher Temperature, by adding in the melt of the polymer or by Add to suspended or dissolved polymer during its processing. You may also already be added to the starting materials for the preparation of the polymer and lose even in the presence of other common light and heat stabilizers, oxidizing and reducing agents, and the like their absorption capacity is not.

A molding composition particularly preferred for the purposes of the present invention has a softening temperature of not less than 80 ° C (Vicat softening temperature VET ( ISO 306-B50 )). It is therefore particularly suitable as a solidifying agent for solar cell modules, since it does not begin to creep, even if the module is exposed to high temperatures in use.

Especially Also advantageous are molding compositions which have a comparatively high Possess total light transmittance and in this way in particular in the application of the molding composition as a solidifying agent prevent a power loss of the solar cell in solar cell modules, which may be due to optical loss of the solidifying agent could. Over the wavelength range from 400 nm to less than 500 nm is the total light transmittance preferably at least 90%. Over the wavelength range from 500 nm to less than 1000 nm is the total light transmittance preferably at least 80% (measurement using the spectral photometer Lambda 19 from the company Perkin Elmer).

Furthermore, molding compositions are also advantageous which have a discharge resistance of 1-500 kΩ × cm ^2. A decrease in the power of the solar cell due to short-circuits is best avoided.

Molding compounds, containing the said ingredients are particularly suitable as solidifying agent for solar cell modules. Farther They are preferably used for the production of so-called light concentrators used. These are components that produce light with high efficiency concentrate on the smallest possible area, So achieve a high irradiance. It is included not necessary to create an image of the light source.

For the purposes of the present invention particularly advantageous Lichtkonzentratoren are collecting lenses that collect parallel irradiated light and in the focal plane. In particular, this is parallel Focused on the optical axis light focused at the focal point.

converging lenses can biconvex (arched outward on both sides), plano-convex (1 side plan, 1 side convex) or concave-convex (1 Side curved inwards, 1 side outward arched, wherein the convex side is preferably more curved is considered the concave). Particularly according to the invention preferred converging lenses comprise at least one convex portion, plano-convex structures being particularly advantageous have proven.

in the Within a particularly preferred embodiment of the present invention, the light concentrators have the structure a Fresnel lens. This is an optical one Lens, which, by virtue of the construction principle used, is generally and volume reduction leads, which in particular at large lenses with short focal length.

The Volume reduction occurs in the Fresnel lens a division into annular areas. In each of these Areas, the thickness is reduced so that the lens is a row annular steps receives. Because light is only on the Surface of the lens is refracted, the angle of refraction is not on the thickness, but only on the angle between the two Surface of a lens dependent. Therefore, keep the lens is at its focal length, although the picture quality is degraded by the step structure. As part of a first, especially preferred embodiment of the present invention be rotationally symmetric lenses with a Fresnel structure used to the optical axis. They focus the light in a direction to a point.

in the Frame of another particularly preferred embodiment The present invention uses Fresnel linear lenses Used structure that focus the light in one plane.

Furthermore For example, the solar cell module may have a structure known per se. It preferably comprises at least one photovoltaic element, the appropriate way between a disc and a rear wall is inserted and laminated, wherein the Slice and the rear wall in a favorable manner respectively attached to the photovoltaic element with a solidifying agent are. In this case, the solar cell module, in particular the disc, the back wall and / or the solidifying agent, preferably the components used according to the invention, d. H. the polyalkyl (meth) acrylate and the compound of the general Formula (I).

• a) mindestens ein photovoltaisches Element,
• b) mindestens einen Lichtkonzentrator, der mindestens ein Polyalkyl(meth)acrylat enthält, und
• c) mindestens eine transparente Scheibe, die mindestens eine Verbindung der allgemeinen Formel der Formel (I) enthält
  
  in der R für einen gegebenenfalls substituierten Alkyl-, Cycloalkyl-, Aralkyl- oder Arylrest steht und der Ring A weitere Substituenten aufweisen kann.

Within the scope of a further very particularly preferred embodiment of the present invention, the solar cell module comprises

• a) at least one photovoltaic element,
• b) at least one light concentrator containing at least one polyalkyl (meth) acrylate, and
• c) at least one transparent pane containing at least one compound of the general formula of formula (I)
  
  in which R is an optionally substituted alkyl, cycloalkyl, aralkyl or aryl radical and the ring A may have further substituents.

A particularly advantageous construction of a solar cell module will be described below with occasional reference to the figures 1 to 2 B described.

The solar cell module according to the invention preferably comprises a photovoltaic element 101 , a slice 103 covering the front of the photovoltaic element 101 covered, a first solidifying agent 102 between the photovoltaic element 101 and the disc 103 , a back wall 105 that the back 104 of the photovoltaic element 101 covered and a second solidifying agent 104 between the photovoltaic element 101 and the back wall 105 ,

The The photovoltaic element preferably comprises a photoactive semiconductor layer on a conductive substrate as a first electrode for light conversion and a transparent conductive layer as a second electrode formed thereon.

The conductive substrate preferably comprises in this context stainless steel, increasing the adhesion strength of the solidifying agent is further improved on the substrate.

A Collecting electrode containing copper and / or silver as an ingredient, is preferably on the photosensitive side of the photovoltaic Element formed and a polyalkyl (meth) acrylate, preferably at least containing a compound of the formula (I) is preferably brought into contact with the collecting electrode.

The photosensitive surface of the photovoltaic element is conveniently treated with a polyalkyl (meth) acrylate, which preferably contains at least one compound of the formula (I), and then preferably a thin fluoride polymer film arranged as the outermost layer on it.

The first solidifying agent 102 should the photovoltaic element 101 Protect from outside exposure by causing bumps in the photosensitive surface of the photovoltaic element 101 covered. Furthermore, it also serves to the disc 103 to the photovoltaic element 101 to bind. Therefore, it should have high weather resistance, high adhesion and high heat resistance in addition to high transparency. Furthermore, it should show a low water absorption and release no acid. In order to satisfy these desires, a polyalkyl (meth) acrylate is preferably used as the first solidifying agent which preferably contains at least one compound of the formula (I).

To minimize a reduction in the amount of light that the photovoltaic element 101 is reached, the light transmittance of the first solidifying agent 102 in the visible wavelength range from 400 nm to 800 nm, preferably at least 80%, particularly preferably at least 90% in the wavelength range from 400 nm to less than 500 nm (measurement using the spectral photometer Lambda 19 from Perkin Elmer). Furthermore, it preferably has a refractive index of 1.1-2.0, advantageously 1.1-1.6, to facilitate the incidence of light from air (measurement after ISO 489 ).

The second solidifying agent 104 is used to the photovoltaic element 101 Protect against outside hazards by removing bumps on the back of the photovoltaic element 101 to be covered. Furthermore, it also serves the back wall 105 to the photovoltaic element 101 to bind. Therefore, the second solidifying agent such as the first solidifying agent should have high weather resistance, high adhesion and high heat resistance. It is therefore preferable to use a polyalkyl (meth) acrylate which preferably contains at least one compound of the formula (I) as a second solidifying agent. Preferably, the same material is used for both the first solidifying agent and the second solidifying agent. However, since the transparency is optional, if necessary, a filler such as an organic oxide may be added to the second solidifying agent to further improve the weatherability and the mechanical properties, or a pigment may be added to color it.

As a photovoltaic element 101 Preferably, known elements, in particular monocrystalline silicon cells, multicrystalline silicon cells, amorphous silicon and microcrystalline silicon are used, as they are also used in thin-film silicon cells. Furthermore, copper-indium-selenide and semiconductor compounds are particularly suitable.

A schematic block diagram of a preferred photovoltaic element is shown in FIG 2a and 2 B shown. 2a is a schematic cross-sectional view of a photovoltaic element, whereas 2 B is a schematic plan view of a photovoltaic element. In these figures designate net the number 201 a conductive substrate, 202 a reflective layer on the back, 203 a photoactive semiconductor layer, 204 a transparent, conductive layer, 205 a collecting electrode, 206a and 206b Alligator clips and 207 and 208 conductive, adhesive or conductive pastes.

The conductive substrate 201 not only serves as a substrate of the photovoltaic element, but also as a second electrode. The material of the conductive substrate 201 preferably comprises silicon, tantalum, molybdenum, tungsten, stainless steel, aluminum, copper, titanium, a carbon foil, a leaded steel plate, a resin film and / or ceramic having a conductive layer thereon.

On the conductive substrate 201 is preferably a metal layer, a metal oxide layer, or both as a reflective layer 202 provided on the back. The metal layer preferably comprises Ti, Cr, Mo, B, Al, Ag and / or Ni, whereas the metal oxide layer preferably contains ZnO, TiO ₂ and SnO ₂ . The metal layer and the metal oxide layer are suitably formed by vapor deposition by heating or by electron beam or by sputtering.

The photoactive semiconductor layer 203 serves to carry out the photoelectric conversion. Preferred materials in this context include pn junction polycrystalline silicon, amorphous silicon pin junction types, microcrystalline silicon pin junction types, and semiconductor compounds, particularly CuInSe ₂ , CuInS ₂ , GaAs, CdS / Cu ₂ S, CdS / CdTe, CdS / InP and CdTe / Cu ₂ Te. The use of pin junction types made of amorphous silicon is particularly preferred.

The Production of the photoactive semiconductor layer is preferably carried out by transforming molten silicon into a foil, or by Heat treatment of amorphous silicon in the case of polycrystalline silicon Silicon, by plasma gas phase deposition using a Silane gases as starting material in the case of amorphous silicon and microcrystalline silicon and by ion plating, ion beam deposition, Vacuum evaporation, sputtering or plating in the case of a semiconductor compound.

The transparent conductive layer 204 serves as the upper electrode of the solar cell. It preferably comprises In ₂ O ₃ , SnO ₂ , In ₂ O ₃ -SnO ₂ (ITO), ZnO, TiO ₂ , Cd ₂ SnO _4, or a crystalline semiconductor layer doped with a large concentration of impurities. It can be formed by resistance heating vapor deposition, sputtering, spraying, vapor deposition or by diffusion of impurities.

Incidentally, in the photovoltaic element on which the transparent conductive layer 204 has been formed, the conductive substrate and the transparent conductive layer partly because of the unevenness of the surface of the conductive substrate 201 and / or the nonuniformity at the time of formation of the photoactive semiconductor layer. In this case, there is a large current loss proportional to the output voltage. Ie. the leakage resistance (shunt resistance) is low. Therefore, it is desirable to eliminate the short circuits and to subject the photovoltaic element to a defect-removing treatment after the formation of the transparent conductive layer. Such a treatment is in the patent US 4,729,970 described in detail. By this treatment, the shunt resistance of the photovoltaic element is set to 1-500 kΩ × cm ² , preferably to 10-500 kΩ × cm ² .

On the transparent conductive layer 204 the collecting electrode (grid) can be formed. It is preferably in the form of a grid, a comb, a line or the like to effectively collect the electric current. Preferred examples of the material containing the collecting electrode 205 are Ti, Cr, Mo, W, Al, Ag, Ni, Cu, Sn or a conductive paste called silver paste.

The collecting electrode 205 is preferred by sputtering using a masking pattern, by resistance heating, by vapor deposition, by a method comprising the steps of forming a metal film over the entire layer by gas deposition and removing unnecessary parts of the film by etching, by a method in which to form a lattice electron pattern by photochemical vapor deposition by a method comprising the steps of forming a negative marking pattern of the grid electrode and plating the patterned surface by a method of printing a conductive paste by a method of using metal wires Soldered on a printed conductive paste formed. As the conductive paste, there is preferably used a binder polymer in which silver, gold, copper, nickel, carbon or the like is dispersed in the form of a fine powder. The binder polymer preferably includes polyester resins, ethoxy resins, acrylic resins, alkyd resins, polyvinyl acetate resins, rubbers, urethane resins, and / or phenolic resins.

Finally, preferably alligator clips 206 on the conductive substrate 201 or at the collecting electrode 205 attached to tap the electromotive force. The attachment of the alligator clips 206 on the conductive substrate is preferably achieved by a metal body such. As a copper nose, attached to the conductive substrate by spot welding or soldering, while the attachment of Abgreifenden to the collecting electrode is preferably accomplished by placing a metal body with the collecting electrode by means of a conductive paste or by means of solder 207 and 208 connects electrically.

The photovoltaic elements are chosen according to the desired Voltage or current either in series or in parallel connected. Furthermore, the voltage or current be controlled by putting the photovoltaic elements in one Insulating substrate inserts.

The disc 103 in 1 should have the highest possible weather resistance, the best possible dirt-repellent effect and the greatest possible mechanical strength, since it is the outermost layer of the solar cell module. Furthermore, it should ensure the long-term reliability of the solar cell module in outdoor use. Discs that may be suitably used for the purposes of the present invention include (reinforced) glass sheets and fluoride polymer films. As the glass sheet, a glass sheet having high light transmittance is preferably used. Suitable fluoride polymer films include, in particular, ethylene tetrafluoride-ethylene copolymer (ETFE), polyvinyl fluoride resin (PVF), polyvinylidene fluoride resin (PVDF), tetrafluoroethylene resin (TFE), ethylene tetrafluoride-propylene hexafluoride copolymer (FEP), and chlorotrifluoroethylene (CTFE). The polyvinylidene fluoride resin is particularly suitable in terms of weatherability, while the ethylene tetrafluoride-ethylene copolymer is particularly advantageous in terms of the combination of weatherability and mechanical strength. In order to improve the adhesion between the fluoride polymer film and the solidifying agent, it is desirable to subject the film to a corona treatment or a plasma treatment. Furthermore, stretched film is also preferably used to further improve the mechanical strength.

in the Within a particularly preferred embodiment of the present invention, the disc comprises at least one polyalkyl (meth) acrylate, that furthermore preferably contains at least one compound of the formula (I) contains

The Disc is also preferably a light concentrator, the light concentrated on the photovoltaic element with high efficiency, So achieved a high irradiance. Especially preferred are collecting lenses that collect parallel irradiated light and in the focal plane. In particular, the focused light parallel to the optical axis focused at the focal point.

The Compound lenses can be biconvex, plano-convex or concave-convex be. However, plano-convex structures are particularly preferred. Furthermore, the disk preferably has the structure of a Fresnel lens on.

The back wall 105 serves the electrical insulation between the photovoltaic element 101 and the environment and to improve the weather resistance and acts as a reinforcing material. It is preferably formed of a material which ensures sufficient electrical insulating properties, has excellent long term durability, can withstand thermal expansion and thermal contraction, and is flexible. Particularly suitable materials for these purposes include nylon films, polyethylene terephthalate (PET) films, and polyvinyl fluoride films. When moisture resistance is required, it is preferred to use aluminum-laminated polyvinyl fluoride films, aluminum-coated PET films, silica-coated PET films. Furthermore, the fire resistance of the module can be improved by using a foil-laminated galvanized iron foil or a frost-free steel foil as the back wall.

in the Within a particularly preferred embodiment of the present invention comprises the rear wall at least a polyalkyl (meth) acrylate, preferably further at least one Compound of formula (I) contains.

On the outer surface of the rear wall can a supporting plate attached to the mechanical Strength of the solar cell module to improve or to a Bulging and bending of the back wall as a result of temperature changes to prevent. Particularly preferred back walls are sheets of frost-free steel, plastic sheets and sheets made FRP (fiber reinforced plastic). Furthermore, a building material be attached to the rear window.

The Production of such a solar cell module can be based on known manner. Especially useful However, this is a procedure that will be described below.

Around to cover the photovoltaic element with the solidifying agent, For example, it is preferable to use a method in which the solidifying agent thermally melted and extruded through a slot to a Form film, which is then thermally attached to the element. The Solidifying film is preferably between the element and the disc is inserted and between the element and the rear wall and then solidified.

to Performing the thermal consolidation can known methods such. B. vacuum lamination and roll lamination be used.

The Solar cell module according to the invention preferably an operating temperature of up to 80 ° C or higher, especially at high temperatures, the heat-resistant Effect of the molding composition according to the invention, preferably contains the ingredients of the invention can be used effectively.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1065731 A2 [0008]
• - DE 1801221 B1 [0010]
• - WO 2008/025738 [0012]
• - US Pat. No. 6433044 B1 [0014]
• - JP 2005-298748 A [0016]
• US 4729970 [0079]

Cited non-patent literature

• - H. Rauch-Puntigam, Th. Völker, "Acrylic and Methacrylic Compounds ", Springer, Heidelberg, 1967 [0033]
• Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 1, p . 386 et seq., J. Wiley, New York, 1978 [0033]
• - H. Rauch-Puntigam, Th. Völker, "Acrylic and Methacrylic Compounds", Springer, Heidelberg, 1967 [0035]
• - Houben-Weyl, Methods of Organic Chemistry, Rd. XIV / 1, page 66, Georg Thieme, Heidelberg, 1961 [0035]
• Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 1, p. 296 et seq., J. Wiley, New York, 1978 [0035]
• - ISO 306-B50 [0052]
• - ISO 489 [0070]

Claims (16)

Use of a) at least one polyalkyl (meth) acrylate and b) at least one compound of the general formula of the formula (I)

in which R is an optionally substituted alkyl, cycloalkyl, aralkyl or aryl radical and the ring A may have further substituents for the preparation of solar cell modules. Use according to claim 1, characterized in that the molding composition comprises at least one C ₁ -C ₁₈ alkyl (meth) acrylate homopolymer or copolymer. Use according to claim 2, characterized in that the molding composition contains at least one copolymer comprising 80% by weight to 99% by weight of methyl methacrylate units and 1% by weight to 20% by weight of C ₁ -C ₁₀ -alkyl acrylate Units. Use according to claim 3, characterized that the copolymer is methyl acrylate and / or ethyl acrylate units includes. Use according to at least one of the preceding Claims, characterized in that in formula (I) the R radicals for acyl groups having 1 to 18 carbon atoms or for cycloalkyl groups 1 to 18 carbon atoms. Use according to claim 5, characterized in formula (I), the radicals R represent alkyl groups with 1 to 8 carbon atoms. Use according to claim 6, characterized in formula (I), the radicals R are ethyl. Use according to at least one of the preceding claims, characterized in that the molding composition contains at least one compound of the general formula of the formula (II)

wherein R ', each independently, is ethyl, n-dodecyl, cyclohexyl, benzyl or phenyl. A solar cell module comprising moldings comprising a) at least one polyalkyl (meth) acrylate and b) at least one compound of the general formula of the formula (I)

in which R is an optionally substituted alkyl, cycloalkyl, aralkyl or aryl radical and the ring A may have further substituents. Solar cell module according to claim 9, characterized in that that the molded part is a light concentrator. Solar cell module according to claim 10, characterized in that that the molded part is a converging lens. Solar cell module according to claim 11, characterized in that the converging lens comprises a convex area. Solar cell module according to claim 12, characterized in that the convergent lens has a plano-convex structure. Solar cell module according to claim 13, characterized in that that the converging lens is a Fresnel lens. Solar cell module according to at least one of the claims 10 to 14, characterized in that it further comprises a photovoltaic Element comprises. A solar cell module, comprising a) at least one photovoltaic element, b) at least one convergent lens containing at least one polyalkyl (meth) acrylate, and c) at least one transparent pane containing at least one compound of the general formula of the formula (I)

in which R is an optionally substituted alkyl, cycloalkyl, aralkyl or aryl radical and the ring A may have further substituents.