Photovoltaic element

description

The invention relates to a photovoltaic element comprising an upper embedding film material and a lower embedding film material, photovoltaic cells being embedded between the upper and lower embedding film material, and the upper embedding film material being formed by a composite material comprising a plastic layer and transparent fibers.

A commercially available photovoltaic module is on the front side (the side facing the sun) from a glass pane, an underlying transparent embedding film to embed the PV cells and their electrical wiring (solder ribbon) to the glass. Below the electronics with the PV cells, there is typically another embedding film and the rear closure is formed by a film laminate, the so-called rear film, which is formed, for example, from a PVF-PET-PVF laminate (polyvinyl fluoride-polyethylene terephthalate-polyvinyl fluoride laminate). The embedding foils are typically made of EVA (polyethylene vinyl acetate). All layers are placed on top of each other when the modules are assembled and thermally laminated to one another. The EVA is chemically cross-linked. During lamination, the previously milky EVA film is transformed into a clear, three-dimensionally cross-linked plastic layer that can no longer be melted, in which the PV cells are embedded and which is firmly connected to the glass pane and the backing film.

But there are also flexible photovoltaic elements in which the glass pane is replaced by a polymer material. For example, EP 2 863 443 A1 shows a photovoltaic panel with at least one solar cell, which is covered at least on its side facing the light and its opposite side facing away from the light with a transparent composite material, which is a glass fiber reinforced plastic based on an acrylate containing epoxy groups. On the side facing the light, the solar cells are embedded in a layer of EVA (ethylene vinyl acetate). This not only provides a panel that is as flexible as possible, but also has a relatively low weight.

A solar cell module is known from EP 0 769 818 A2, comprising a solar cell element and at least one surface-side covering material, which is positioned on the light-receiving side of the solar cell element, the surface-side covering comprising at least one encapsulation element, a glass fiber fleece and a surface protective film, wherein the fiberglass mat has a texture bonded with an acrylic resin.

WO 2016/183604 A1 describes a photovoltaic element comprising an upper embedding film material and a lower embedding film material, photovoltaic cells being embedded between the upper and lower embedding film material, and a rear film material which is arranged below the lower embedding film material in the installed position of the photovoltaic element, and which is formed by a composite film, comprising at least one plastic layer and at least one fiber reinforcement. At least one of the two embedding film materials can have a physically crosslinked plastic.

US 2011/023943 A1 describes a mixture composition that can be used as a crosslinkable encapsulation layer and consists essentially of two ethylene copolymers and optionally one or more additives. The first ethylene copolymer comprises copolymerized ethylene units, optionally a first olefin having the formula CH2=C(R1)CO2R2 and a second olefin having the formula CH2=C(R3)COOH. The second ethylene copolymer consists essentially of copolymerized ethylene units, optionally a first olefin having the formula CH2=C(R1)CO2R2 and a third olefin having the formula CH2=C(R4)D. R1, R3 and R4 are hydrogen or an alkyl group, R2 is an alkyl group and D is a moiety containing an epoxy group. Furthermore, solar cell modules are provided which comprise the encapsulation layer. The encapsulant layer comprises the blend composition or the product of crosslinking the blend composition in which some acid groups of the second olefin have reacted with some epoxy groups of the third olefin.

[0007] DE 10 2011 053 030 A1 discloses a solar module comprising a first /13

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layer, a solar cell arranged above the first layer and a second layer arranged above the solar cell, the first and/or the second layer comprising a fiber composite material which comprises a polyurethane polymer crosslinked thermally and by means of electromagnetic radiation and the material of the fibers of the fiber composite material being at least is transparent in the visible light range.

WO 2013/119113 A1 describes a photovoltaic module comprising a panel comprising at least one photovoltaic cell and a layer of encapsulation material covering at least the light-incident side of the panel, the encapsulation material comprising a transparent composite material comprising a fiber-reinforced thermoplastic polymer includes.

[0009] KR 2016-0120950 A relates to an encapsulation material for a photocell module, a manufacturing method therefor and a photocell module containing an encapsulation material. The encapsulation material includes a layer containing glass fibers to improve flame retardancy.

US 6,114,046 A describes, inter alia, a method for the production of an encapsulant material, in which a sheet of metallocene polyethylene is provided, a first layer of an ionomer is applied to a front surface of the sheet of metallocene polyethylene, and adjoining a second layer of an ionomer to a reverse surface of the metallocene polyethylene film, each of the two ionomer layers having at least 4% by weight free acid content.

The present invention is based on the object of improving a photovoltaic element with regard to its property as a building-integrated element (BIPV).

This object is achieved with the photovoltaic element mentioned at the outset in that the plastic layer of the upper embedding film material has a physically crosslinked plastic and that the photovoltaic cells are embedded in a photovoltaic layer formed from a plastic and the photovoltaic cells with their electrical contacts.

The advantage here is that the use of the upper embedding film material no longer requires a glass pane to cover the outside, with the physically cross-linked plastic avoiding the formation of fission products from the polymer during use of the photovoltaic element. In addition, the lamination process itself can also be simplified in this way. The lamination time can be reduced by using a physically cross-linked plastic, since no chemical cross-linking reaction is necessary. The photovoltaic cells can be covered on the outside by the fiber layer itself, whereby the external appearance of the photovoltaic element can be changed since the photovoltaic cells are no longer visible or have a different appearance when viewed through the fiber layer. This change allows the photovoltaic element to be better integrated into a building facade or into a building element. An upper embedding film material facing the sun can thus be made available which, despite the covering of the photovoltaic cells, has a relatively high transmission of sunlight.

The physically crosslinked plastic of the plastic layer of the embedding film material can be an ionomer according to a preferred embodiment. The optical properties, such as refractive index and transmittance, can thus be improved over the entire service life of the photovoltaic element. In particular, the optical properties of the fiber layer cannot be retained, or only slightly altered. In addition, the upper embedding film material can thus be given better scratch resistance, with which the photovoltaic element can be better adapted to the environmental stresses. The improved scratch resistance also contributes to the preservation of the optical properties of the photovoltaic element over a longer period of time.

According to one embodiment of the photovoltaic element, the ionomer is preferably a zinc ionomer based on ethylene/methacrylic acid copolymer. Compared to other lonome

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AT 522 993 B1 2023-05-15 Austrian patent office this ionomer has good flow properties, high impact strength and low moisture absorption. In addition, improved adhesion to the fiber layer can also be achieved in this way.

According to another embodiment of the photovoltaic element can be provided that the transparent fibers form their own fiber layer, whereby a better connection of the upper embedding film material to the layer with the photovoltaic cells can be achieved.

It can be provided according to a further embodiment of the photovoltaic element that the fiber layer has a proportion of the plastic of the plastic layer of the upper embedding film material of at most 10% by weight. By avoiding the penetration of the fiber layer by the plastic of the plastic layer of the upper embedding film material, a further improvement in the aforementioned effects regarding the change in the optical properties of the fiber layer can be achieved.

According to one embodiment of the photovoltaic element can be provided that the plastic of the plastic layer of the upper embedding film material is contained up to a thickness of the fiber layer, which is a maximum of 20% of the total thickness of the fiber layer. The effects mentioned above can thus be improved, and at the same time the connection of the plastic layer to the fiber layer can be improved if the plastic of the plastic layer penetrates slightly into the fiber layer.

According to a further embodiment of the photovoltaic element can be provided that the fiber layer has a basis weight of at least 100 g / m²and maximum 150 g/m²having. Relatively high light yields of the photovoltaic cells can thus be achieved, since transmission values of significantly more than 50% can be obtained with a fabric of this basis weight.

It can also be advantageous if, according to another embodiment, the fabric of the fiber layer is a glass filament fabric. The structural strength of the embedding film material can thus be improved, so that a photovoltaic element equipped with it can better withstand the environmental conditions.

According to a further embodiment it can be provided that the lower embedding film material is of the same design as the upper embedding film material. This not only simplifies the production of the photovoltaic element, but also makes it easier to use the photovoltaic element as a bifacial photovoltaic element, since the back of the photovoltaic element has a relatively high permeability for sunlight reflected from surfaces located below the photovoltaic element.

According to another embodiment of the photovoltaic element can be provided that the plastic of the photovoltaic layer is a physically cross-linked plastic. The lamination time can be further reduced by using a physically cross-linked plastic, since no chemical cross-linking reaction is necessary.

According to a variant embodiment of the photovoltaic element, it can be provided that the plastic of the photovoltaic layer is the same as the plastic of the plastic layer of the upper embedding film material, with which the system integrity can be improved.

For a better understanding of the invention, this is explained in more detail with reference to the following figure.

It partially shows in a simplified, schematic representation:

[0026] FIG. 1 shows a section of a photovoltaic element in cross section;

Figure 2 shows the transmission spectrum of embedding film materials;

Figure 3 reflectance spectrum of embedding film materials.

Introductory it should be noted that in the different described Ausführungsfor

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AT 522 993 B1 2023-05-15 Austrian patent office, the same parts are provided with the same reference numbers or the same component designations, it being possible for the disclosures contained throughout the description to be applied to the same parts with the same reference numbers or the same component designations. The position information chosen in the description, such as top, bottom, side, etc. refers to the directly described and illustrated figure and these position details are to be transferred to the new position in the event of a change in position.

In Fig. 1 a section of a first embodiment of a photovoltaic element 1 is shown in cross section.

This photovoltaic element 1 comprises an upper embedding film material 2, a photovoltaic layer 3 arranged underneath and connected to the upper embedding film material 2, in which several photovoltaic cells 4 are contained or embedded, and a lower embedding film material 5, which is connected to the photovoltaic layer 3 and below is arranged by this, or consists of these components. This layer structure can be bordered by a frame 6 which is preferably arranged to cover the upper embedding film material 2 and the lower embedding film material 5.

The photovoltaic cells 4 and their electrical contacting or wiring, which is only shown in outline in FIG. 1, are embedded in a plastic that forms the photovoltaic layer 3 together with the photovoltaic cells.

According to the preferred embodiment variant of the photovoltaic element 1, the plastic of the photovoltaic layer 3 can be a physically crosslinked plastic, so that it is free of crosslinking agents or cleavage products thereof. For example, the plastic can be an ionomer. However, a vinyl copolymer such as polyvinyl butyral, or a thermoplastic elastomer, etc. may also be used. The ionomer can be selected from a group comprising or consisting of ionomeric (co)polymers of ethylene and an α,β-unsaturated carboxylic acid or a carboxylic acid anhydride of this carboxylic acid, in particular (co)polymers of ethylene and methacrylic acid.

The physical crosslinking can take place via ionic bonds in the ionomer, with Zn²⁺or approx²⁺or Mg²⁺or well⁺or K⁺or other metal ions act as cations and carboxyl groups of the plastic act as anions.

It should be pointed out, however, that in principle it is also possible to use polymers which can be softened by appropriate stimulation and crosslink three-dimensionally as a result of heating or after subsequent cooling.

The plastic of the photovoltaic layer 3 can be used to produce the photovoltaic element 1 as a single-layer or multi-layer film.

[0037] Preference is given to those polymers whose excitation is thermally possible, since the physical crosslinking can then be better integrated into a lamination process for the production of the photovoltaic element 1.

With regard to the lamination process per se, reference is made to the relevant prior art.

With regard to further details on the photovoltaic cells 4, reference is made to the relevant prior art.

The upper embedding film material 2 is formed by a composite material, for example a composite film, which comprises or is formed from at least one plastic layer 7 and at least one fiber layer 8.

According to one embodiment, the fiber layer 8 can be formed as a separate layer, which is arranged between the plastic layer 7 and the photovoltaic cells 4, wherein in the embodiment of the photovoltaic element 1 according to Figure 1 between the fiber layer 8 and the photovoltaic cells 4 the plastic the photovoltaic layer 3, in which the photovoltaic cells 4 are embedded, is arranged. Should be formed in the fiber layer 8 cavities

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AT 522 993 B1 2023-05-15 Austrian patent office, at least 30%, in particular at least 50%, based on the total cavity volume, cannot be filled with the plastic of the plastic layer 7 and/or the plastic of the photovoltaic layer 3.

According to one embodiment variant of the photovoltaic element 1, the fiber layer 8 can have a proportion of the plastic of the plastic layer 7 of at most 10% by weight, in particular at most 8% by weight, preferably at most 6.5% by weight. The fiber layer 8 can also be completely free of the plastic of the plastic layer 7.

In addition, the fiber layer 8 in the embodiment variant with photovoltaic cells 4 embedded in the plastic of the photovoltaic layer 3 can have a proportion of this plastic of the photovoltaic layer 3 of at most 10% by weight, in particular at most 8% by weight, preferably at most 6.5 % by weight.

According to one embodiment variant of the photovoltaic element 1, it can be provided that the plastic of the plastic layer 7 is contained up to a thickness of the fiber layer 8 which is at most 20%, in particular at most 15%, preferably at most 10%, of the total thickness 9 of the fiber layer 8 amounts to.

The plastic of the photovoltaic layer 3 can be contained in the fiber layer 8 up to a thickness which is a maximum of 20%, in particular a maximum of 15%, preferably a maximum of 10%, of the total thickness 9 of the fiber layer 8.

The thickness of the partial layer with the plastic of the plastic layer 7 or the plastic of the photovoltaic layer 3 is measured from the respectively associated surface of the fiber layer 8.

The fiber layer 8 is formed from or consists of transparent fibers and/or threads. The fibers and/or threads can be selected from a group comprising or consisting of glass fibers, organic fibers, in particular polymer fibers, and combinations thereof.

Glass fibers are preferably used exclusively for the fiber layer 8.

The fibers and/or threads can be present in the fiber layer 8 as a scrim, for example as a fleece. However, a woven fabric or a knitted fabric made of the fibers and/or threads is preferably used, in particular a glass filament fabric according to an embodiment variant of the photovoltaic element 1.

[0050] When using a woven fabric, different types of weave are possible, in particular plain weave, twill weave or satin weave. A plain weave is preferably used. The basis weight of the fiber layer 8 can be between 10 g/m² und 1000 g/m²be. According to one embodiment variant of the photovoltaic element 1, a fiber layer 8 with a surface weight of between 100 g/m is preferred for the above reasons² und 150 g/m²deployed. A closed layer can thus be produced, which enables a uniform material connection to the plastic of the plastic layer 7. In addition, properties of the composite material, such as thermal expansion or creep, can be influenced.

However, it is also possible to use an open-meshed glass fabric or non-crimp fabric with a surface weight of between 10 g/m² bis 90 g/m²to use, although this is not the preferred embodiment of the photovoltaic element 1.

The fiber layer 8 can be formed as a single layer. However, it is also possible for the fiber layer 8 to have several individual layers, for example two or three, in which case at least some of the several individual layers can also consist of fibers and/or threads that are different from the rest of the individual layers, at least in some areas, preferably entirely.

According to another embodiment of the photovoltaic element 1 can be provided that the fibers of the fiber layer 8 partially or fully in the plastic art

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AT 522 993 B1 2023-05-15 Austrian patent office material layer 7 of the upper embedding film material 2 are embedded.

The plastic layer 7 of the upper embedding film material 5 consists of at least 80% by weight, in particular at least 90% by weight, preferably 100% by weight, of a physically crosslinked plastic. If the fiber layer 8 is at least partially embedded in the plastic layer 7, the proportion of plastic in the plastic layer 7 is reduced accordingly. If the fiber layer 8 only extends over a portion of the layer thickness of the plastic layer 7, the above values for the proportion of plastic in the plastic layer 7 apply to that portion of the layer thickness in which there are no fibers or threads, i.e. no mixed area is present.

It should be mentioned at this point that a plastic is understood to mean a synthetic or natural polymer which is produced from appropriate monomers.

So no chemical crosslinking agent is added to crosslink the plastic of the plastic layer 7, so that the finished plastic in the photovoltaic element 1 is also free of such chemical crosslinking agents or cleavage products thereof.

According to the preferred embodiment, the physically crosslinked plastic of the plastic layer 7 is an ionomer, according to an embodiment of this a zinc ionomer based on ethylene/methacrylic acid copolymer. The physical crosslinking takes place via ionic bonds in the ionomer, with Zn²⁺acts as a cation and the carboxyl group of the main chain acts as an anion.

Vinyl copolymers, such as polyvinyl butyral, or thermoplastic elastomers can also be used as the physically crosslinked plastic.

It is also possible that the photovoltaic element 1 has more than one layer of an ionomer. For example, the lower embedding film material 5 can also have a (different) ionomer. Likewise, as has already been explained above, the plastic of the photovoltaic layer 3 can also comprise an ionomer.

It should be pointed out in this context that the upper embedding film material 2 can have the same ionomer as the photovoltaic layer 3. The above statements on the ionomer of the photovoltaic layer 3 can therefore also be applied to the ionomer of the upper embedding film material or vice versa the statements regarding the ionomer of the upper embedding sheet material 2 can be applied to the ionomer of the photovoltaic layer 3.

The ionomer of the top encapsulant sheet material 2 can be selected from a group consisting of ionomeric (co)polymers of ethylene and an α,β-unsaturated carboxylic acid or a carboxylic acid anhydride of this carboxylic acid, in particular (co)polymers of ethylene and methacrylic acid.

The ionomer preferably contains carboxylic acid groups which are at least partially neutralized with metal ions selected from the group consisting of sodium, potassium, calcium, magnesium and zinc.

As already stated, the ionomer is preferably a zinc ionomer based on ethylene/methacrylic acid copolymer, which is produced by copolymerization of ethylene with polar acrylic monomers. Compared to other ionomers, the adhesion to glass can be improved. On the other hand, this ionomer also has good flow properties, high impact strength and low moisture absorption.

However, it should be pointed out that in principle it is also possible to use polymers which can be softened by appropriate stimulation and crosslink three-dimensionally as a result of heating or after subsequent cooling.

Such polymers are preferred in which thermal excitation is possible, since the physical crosslinking can then be better integrated into the lamination process for the production of the photovoltaic element 1, in particular no additional processing step for

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Production of the crosslinked plastic is required.

With regard to the lamination process per se, reference is made to the relevant prior art.

According to a further embodiment variant of the photovoltaic element 1, the composite material of the upper embedding film material 2 can have at least one further plastic layer 10 in addition to the fiber layer 8 and the plastic layer 7 (shown in dashed lines in FIG. 1), with the further plastic layer 10 being more stable against exposure to UV radiation, than the plastic layer 7 lying against the fiber layer 8. For this purpose, this further plastic layer 10 can be provided with a UV stabilizer. A UV stabilizer commonly used in the plastics industry can be used as the UV stabilizer.

The plastic layer 10 can consist, for example, of at least 80% by weight, in particular at least 90% by weight, preferably at least 95% by weight, of a physically crosslinked plastic. With regard to the physically cross-linked plastic of the plastic layer 10, reference is made to the statements on the physically cross-linked plastic of the upper embedding film material 2, which can be transferred accordingly to the plastic of the plastic layer 10.

According to one embodiment variant of the photovoltaic element 1, the polymer of the plastic layer 7 lying against the fiber layer 8 is preferably used as the plastic for the further plastic layer 10, ie in particular an ionomer. By this is meant that the polymer has the same monomer units. However, the plastics can have different properties resulting from different degrees of polymerization.

According to a further embodiment variant of the photovoltaic element 1, it can be provided that the further plastic layer 10 has a layer thickness 11 which corresponds to between 10% and 50%, in particular between 10% and 20%, a layer thickness 12 of the plastic layer 7 arranged underneath.

The plastic layer 7 can have a layer thickness 12 of between 10 μm and 300 mm.

According to one embodiment of the photovoltaic element 1, the lower embedding film material 5 can generally be configured in the same way as the upper embedding film material 2, although under certain circumstances the lower (rear) embedding film material 5 does not have the additional UV-stabilized plastic layer 10 can.

In all variants of the photovoltaic element 1, the fabric of the fiber layer 8 can consist of glass fibers, with the glass fibers consisting of an aluminum borosilicate glass or borosilicate glass. In particular, the glass fibers can consist of a glass that has a transmittance of at least 50%, in particular at least 60%, at least for visible light (380 nm to 750 nm).

In general, the layers of the upper embedding film material 2 and/or the lower embedding film material 5 can be connected to one another via an adhesive. On the one hand, 2-component adhesive systems based on polyurethane or hot-melt adhesive systems are suitable for this. In addition to adhesives, coextrusion and extrusion coating can also be used as a possibility of connecting at least the two plastic layers 7, 10 to one another and/or the plastic layers 7 to the fiber layer 8. Of course, a combination is also possible in which plastics are coextruded and adhesively laminated to one another with an extrusion-coated fiber layer 8.

According to another embodiment, it can be provided that the lower embedding film material 5 has a barrier layer, which can be formed in particular by at least one metal foil, in particular an aluminum foil. Not only can this provide the primary barrier function, but the reflection behavior of the lower embedding film material 5 can also be improved, as a result of which the energy yield of the photovoltaic element 1 can be improved. By using a metal foil

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AT 522 993 B1 2023-05-15 Austrian patent office, improved thermal conductivity of the lower embedding film material 5 can also be achieved, as a result of which hot spots during operation of the photovoltaic element 1 can be better prevented. The barrier layer can be arranged between the fiber layer and the plastic layer of the lower embedding sheet material 5.

A possible layer structure for the photovoltaic element 1 can appear as follows:

- Upper embedding film material 2 with an ionomer as the plastic of the plastic layer 7 and a glass filament fabric;

- photovoltaic layer 3 with the photocells 4 embedded in an ionomer;

- Lower embedding film material 5, which preferably also has an ionomer as plastic and a glass filament fabric.

Various tests were carried out to evaluate the materials.

is the transmission spectrum and reflection spectrum of the upper embedding film material 2 with the structure of glass fiber layer 8 / zinc ionomer based ethylene / metacrylic acid copolymer with a layer thickness 12 of 250 microns for electrical insulation / UV stabilized plastic layer 10 made of a zinc ionomer based on ethylene/methacrylic acid copolymer with a layer thickness 12 of 19 μm (wavelength plotted on the abscissa). The layers were connected using a polyurethane-based adhesive, with approximately twice the amount of adhesive being used to connect the fiber layer 8 to the ionomer plastic layer 7 than to connect the ionomer plastic layer 7 to the ionomer plastic layer 10. The Measurement was carried out using a UV-VIS-NIR spectrometer with a 150 mm integrating sphere. The directional hemispherical transmittance (T) and reflectance (R) were recorded in the wavelength range from 250 nm to 2500 nm. The spectra were weighted using the terrestrial solar spectrum AM1.5 in the integration range from 400 nm to 1100 nm.

In the wavelength range from 400 nm to 1100 nm that is relevant for photovoltaic elements 1, a glass fiber fabric has a basis weight of 100 g/m²(Curve 14 in FIG. 2 and curve 15 in FIG. 3) has a light transmission T of approx. 60% and a light reflection R of approx. 18%, a glass fiber fabric per se with a weight per unit area of 200 g/m²(Curve 16 in FIG. 2 and lower curve 17 in FIG. 3) has a light transmission T of approx. 30% and a light reflection R of approx. 62%.

A plastic layer made of the zinc ionomer based on ethylene/methacrylic acid copolymer alone (curve 18 in Fig. 2 and lower curve 19 in Fig. 3) has a light transmission T of approx. 90% and a light reflection R of approx. 10 % on.

The upper embedding film material 2 has fiber layer 8 with a weight per unit area of 100 g/m²(Curve 20 in FIG. 2 and lower curve 21 in FIG. 3) has a light transmission T of approx. 50%-55% and a light reflection R of approx. 40%. With a basis weight of the glass fiber layer 8 of 200 g/m²(Curve 22 in FIG. 2 and lower curve 23 in FIG. 3), the upper embedding film material 2 has a light transmission T of about 30% and a light reflection R of about 63%.

In general, the fabric of the fiber layer 8 can be a flat fabric.

Furthermore, the fabric of the fiber layer 8 can also consist of a mixture of fibers or threads made from different materials, so that the fabric of the fiber layer 8 may also contain reinforcing fibers. The reinforcing fibers are preferably also transparent. The reinforcing fibers can also be selected from a group comprising or consisting of glass fibers, aramid fibers, carbon fibers, mineral fibers such as basalt fibers, natural fibers such as hemp, sisal, and combinations thereof. The reinforcing fibers can be contained in the fiber layer 8 in a proportion which is selected from a range from 2% by weight to 6% by weight. The reinforcing fibers can be woven into the fabric of the fiber layer 8. However, it is also possible that, as an alternative or in addition, the plastic layer 7 contains the reinforcing fibers (in the specified proportion).

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If the photovoltaic element has the frame 6, this can be produced by forming from the composite material of the upper and/or lower film material 2, 5 and in particular can be formed in one piece with it.

In the preferred embodiment variant, the photovoltaic element 1 no longer has any further cover above the upper embedding film material 2, in particular no glass pane.

It can also be advantageous in all variants of the invention if the glass filament fabric is formed from yarns made of glass threads, the yarn for the warp threads having a higher thread density than for the weft threads, in particular a thread density that is at least 10% higher, based on the thread density of the weft threads. The glass filament fabric or the fiber layer 8 can also be provided with a silane size or a textile size.

Finally, for the sake of clarity, it should be pointed out that, for a better understanding of the structure of the photovoltaic element 1, this or its components are sometimes not shown to scale and/or enlarged and/or reduced.

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List of reference symbols

Photovoltaic element

Embedding film material

Photovoltaic layer

Photovoltaic cell

Embedding film material

frame

Plastic layer

Fiber layer

Total thickness

Plastic layer

Layer thickness

Layer thickness

Curve

Curve

Curve

Curve

Curve

Curve

Curve

Curve

Curve

Curve

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