WO2023144207A1

WO2023144207A1 - Method for producing a photovoltaic panel such as a pv integrated vehicle body panel using a thermosetting polymer injected with reaction injection moulding

Info

Publication number: WO2023144207A1
Application number: PCT/EP2023/051808
Authority: WO
Inventors: Christian Brandl; Camillo KAPP; Harshan Ramesha
Original assignee: Sono Motors Gmbh
Priority date: 2022-01-27
Filing date: 2023-01-25
Publication date: 2023-08-03
Also published as: DE102022101935A1

Abstract

A method for producing a photovoltaic panel (1), particularly a photovoltaic vehicle body panel, is described. The method comprises providing a photovoltaic label (3) comprising a front side polymeric stabilisation foil, a front side polymeric lamination foil, a rear side polymeric lamination foil and, optionally, a rear side polymeric stabilisation foil as well as a solar cell arrangement interposed between the front and rear side lamination foils, and preparing a support structure (17) for supporting the photovoltaic label, wherein the support structure is prepared by applying a mouldable thermosetting polymer to at least a rear surface of the photovoltaic label. Therein, the support structure is prepared by applying the thermosetting polymer in a viscous condition using a reaction injection moulding (RIM) procedure, including forming the thermosetting polymer into an intended shape of the panel using a mould by arranging the photovoltaic label in the mould and injecting the thermosetting polymer into the mould and solidifying the thermosetting polymer before removing the support structure formed upon solidifying the thermosetting polymer together with the photovoltaic label from the mould. Thereby, mechanical stress applied to the solar cell arrangement may be reduced and a risk of breaking solar cells may be minimized.

Description

Method for producing a photovoltaic panel such as a PV integrated vehicle body panel using a thermosetting polymer injected with reaction injection moulding

FIELD OF THE INVENTION

The present invention relates to a method for producing a photovoltaic panel, particularly for producing a photovoltaic vehicle body panel, into which a solar cell arrangement is integrated. Furthermore, the present invention relates to the photovoltaic panel, particularly to the photovoltaic vehicle body panel which may optionally be produced with the method described herein.

TECHNICAL BACKGROUND

In the following, the term “photovoltaic” may be abbreviated by “PV”. PV cells may also be referred to as solar cells. Furthermore, while the term “vehicle body panel” may refer to a panel which may be included in a body of any kind of vehicles such as cars, trucks, busses, mobile homes, trains, ships, airplanes, etc., embodiments are described herein with reference to car body panels for simplicity of description.

Conventionally, most commercially available PV panels are typically produced by providing planar, rigid, wafer-based solar cells and then laminating these solar cells between a front side glass sheet and a rear side support structure such as another glass sheet or a metal sheet. Therein, the solar cells are interposed between thin lamination foils serving for both, tightly encapsulating the solar cells and mechanically interconnecting the stack including the front and rear side sheets with the interposed solar cell arrangement. Such PV panels are also referred to as PV modules and have typically a planar structure. These PV panels are well suited for installation on buildings or in solar farms. However, such planar PV panels are hardly suited for an integration into curved surfaces such as for example surfaces of body panels of a car or another vehicle.

Approaches have been presented in which PV cells are provided at a body of a car for generating electricity to be supplied to the car. Such electricity may be used for example for charging batteries of an electric car.

For example, it has been proposed e.g. in an earlier patent application WO 2019/020718 Al of the present applicant to provide solar cells in a body panel of a vehicle. Therein, a PV module shall be placed on top of such body panel or, preferably, the PV module shall be integrated into the body panel. Specifically, one or more solar cells may be arranged in an air tight and water tight manner in a recess provided in a carrier structure of a car body panel.

In an alternative approach for manufacturing PV modules, it has been proposed by the present applicant in an earlier patent application WO 2020/187792 Al to integrate a solar cell arrangement into a moulded layer formed by injection moulding. Therein, the solar cell arrangement is interposed between polymeric foils, thereby forming a so-called photovoltaic label which may be securely handled and in which the solar cells are for example protected against excessive mechanical stress during an injection moulding procedure.

Another approach for a car body panel comprising an integrated solar cell arrangement has been proposed by the present applicant in earlier patent applications PCT/EP2021/083775 and GB

2019566.5 filed in the United Kingdom, having the title “Car body panel including a solar cell arrangement and method for producing same”.

In each of these prior art approaches, the car body panel including the solar cell arrangement may be regarded as a photovoltaic module having a non-planar shape. A body panel of a vehicle including an integrated PV module may be referred to herein as PV integrated car body panel.

Possible features and characteristics of such approaches of car body panels and approaches for fabricating a car body panel including a photovoltaic module have been described by the applicant in the above mentioned patent applications as well as in further prior patent applications such as two patent applications filed in the United Kingdom with the application numbers

2009642.6 (title: “Method for fabricating a photovoltaic module including laser cutting of a photovoltaic label”) and 2009653.3 (title: “Method for fabricating a curved photovoltaic module including adapted positioning of photovoltaic cells”). Features and characteristics of such approaches may also apply to the PV (car body) panel and the production method described herein and the content of the earlier patent applications shall be incorporated in its entirety herein by reference.

SUMMARY OF THE INVENTION AND OF EMBODIMENTS

It may be an object to provide a method for producing a PV panel, particularly a PV car body panel, in which a solar cell arrangement is integrated and which fulfils both, very high functional requirements as well as very high aesthetic requirements. Furthermore, it may be an object to provide a production method which enables a relatively simple fabrication procedure, high fabrication yield and/or low fabrication costs while providing a fabrication result as a highly functional, reliable and aesthetic PV-integrated (car body) panel. Furthermore, it may be an object to provide a PV panel, particularly a PV car body panel, being highly functional and reliable as well as aesthetic and furthermore being producible in a reliable and cost efficient manner.

Such objects may be met with the subject-matter of the independent claims. Advantageous embodiments are defined in the dependent claims and described in the following specification and visualised in the associated figures.

According to a first aspect of the present invention, a method for producing a photovoltaic panel, particularly a photovoltaic car body panel, is described. The method comprising at least the following steps, preferably in the indicated order:

(i) providing a photovoltaic label comprising a front side polymeric stabilisation foil, a front side polymeric lamination foil, a rear side polymeric lamination foil and, optionally, a rear side polymeric stabilisation foil as well as a solar cell arrangement interposed between the front and rear side lamination foils, and

(ii) preparing a support structure for supporting the photovoltaic label, wherein the support structure is prepared by applying a mouldable thermosetting polymer to at least a rear surface of the photovoltaic label.

Therein, the support structure is prepared by applying the thermosetting polymer in a viscous condition using a reaction injection moulding (RIM) procedure, including forming the thermosetting polymer into an intended shape of the panel using a mould by arranging the photovoltaic label in the mould and injecting the thermosetting polymer into the mould and solidifying the thermosetting polymer before removing the support structure formed upon solidifying the thermosetting polymer together with the photovoltaic label from the mould.

According to a second aspect of the invention, a PV panel, particularly a car body panel, is described, the panel including a photovoltaic label and a support structure. The photovoltaic label comprises a front side polymeric stabilisation foil, a front side polymeric lamination foil, a rear side polymeric lamination foil and, optionally, a rear side polymeric stabilisation foil as well as a solar cell arrangement interposed between both lamination foils. The support structure serves for supporting the photovoltaic label and includes a solidified thermosetting polymer being prepared using a reaction injection moulding procedure and being attached to at least a rear surface of the photovoltaic label.

Briefly summarised and without limiting the scope of the invention, basic ideas underlying embodiments of the invention and associated possible advantages will be roughly described as follows:

As indicated above, various approaches for producing PV panels with a potentially curved surface have been suggested by the applicant. For a large volume fabrication of e.g. PV integrated car body panels, the approach as described e.g. in WO 2020/187792 Al is highly promising. Therein, a solar cell arrangement is integrated into a moulded layer of a thermoplastic polymer formed by injection moulding.

However, while such approach of preparing a PV panel by moulding the solar cell arrangement into a support structure prepared by conventional injection moulding appears to allow rapid production of large numbers of PV panels, it has been observed that handling the solar cell arrangement during the injection moulding procedure may be challenging. Particularly, it has been observed that there is a risk that solar cells of the solar cell arrangement break during the injection moulding procedure unless suitable provisions are made for preventing such solar cell breakage.

Actually, it has been found by the inventors that such solar cell breakage may result from the fact that, during conventional injection moulding, a thermoplastic polymer is typically injected into a cavity comprised in a mould, such injection being applied with very high pressures. While such high pressurised injection may enable fast manufacturing, it is assumed that the injected thermoplastic polymer may exert an excessive pressure onto the solar cells in the PV label thereby inducing a risk of solar cell breakage.

In order to reduce such risk of solar cell breakage, it is therefore suggested to replace the conventional injection moulding procedure by a procedure in which a thermosetting polymer is used instead of a thermoplastic polymer for preparing a support structure supporting the PV label including the solar cell arrangement. Particularly, it is suggested to prepare the support structure using a reaction injection moulding (RIM) procedure in which the thermosetting polymer is prepared and injected into a mould for forming the intended shape of the support structure. In such RIM procedure, the thermosetting polymer may also be referred to as reactive polymer as it is generally a reaction product formed by mixing two initially separate chemical components.

Among other benefits, using such thermosetting polymer instead of a thermoplastic polymer allows applying the polymer material with significantly lower pressures than typically used in conventional injection moulding procedures. This may be due to the fact that the thermoplastic polymers used in conventional injection moulding have to be heated in order to become liquid and generally have a high viscosity upon being processed. Due to such high viscosity, the thermoplastic polymers have to be injected into the cavity of the mould at high pressures in order to guarantee that the polymer material fills all portions of the cavity before excessively cooling down and thereby losing its fluid characteristics. While the viscosity of a thermoplastic polymer could, in principle, be lowered by heating the polymer material to higher temperatures, such raising the processing temperatures is typically limited due to the fact that other components such as for example the PV label may be damaged upon being heated to excessive temperatures.

In contrast to thermoplastic material, a viscosity of a thermosetting material is generally not highly dependent on its processing temperature. Instead, generally, thermosetting materials may be processed with one or more liquid components which are highly fluid, i.e. which have a very low viscosity. For example, such thermosetting materials may be composed of at least two liquid components which are mixed immediately before being applied in a moulding procedure. Directly after such mixing action, the resulting fluid has a very low viscosity similar to water or thin oil. Accordingly, such fluid thermosetting polymer may be applied to another component such as a PV label using low pressures. For example, the low-viscosity thermosetting polymer may be injected into a cavity in a mould, may easily flow and spread throughout the cavity and may thereby obtaining the shape and geometry defined by the mould. Due to the application of only low pressures, a risk for damaging other components such as the solar cells comprised in the PV label remains low. Subsequently, the thermosetting polymer may solidify due to e.g. chemical reactions between its components. After such solidification, the support structure formed by the solidified thermosetting material together with the PV label held by such support structure may be removed from the mould. Optionally, the entire moulding product may then be further processed.

In the following, possible features of embodiments of the invention and associated possible advantages will be described in more detail.

The approach proposed herein is particularly suitable for a PV-integrated (car body) panel comprising multiple PV cells which are prepared based on brittle semiconductor wafers. The PV cells may be for example solar cells being fabricated based on crystalline silicon wafers. Such wafer-based Si-PV cells may generally have e.g. a high efficiency of more than 15% (i.e. e.g. between 17% and 26%) and a high reliability. Furthermore, well established industrial processes exist for their fabrication. Such PV cells typically have lateral dimensions of between 50x50 mm² and 300x300 mm², mostly between 150x150 mm² and 200x200 mm², with a square shape, a rectangular shape, a round shape, a semi-round shape or any other shape. Furthermore, such PV cells generally have a thickness of more than 50 pm, typically between 100 pm and 300 pm.

Having such thickness, the PV cells are relatively rigid, i.e. they may generally not be bent into small bending radii of e.g. less than their lateral dimensions. Generally, it may be assumed that, depending on a cell size, bending radii of less than 80 cm, less than 90 cm or less than 100 cm should be avoided.

Each PV cell comprises electric contacts. The electric contacts of neighbouring PV cells may be interconnected via electrical connections such that these PV cells may be electrically connected in series, in parallel or in any combination of series and parallel connections. The electrical connections may be provided by one or more electrically conducting ribbons and/or one or more copper solderings between two adjacent photovoltaic cells, preferably between each two adjacent photovoltaic cells of a respective string. A plurality of interconnected PV cells forms part of a solar cell arrangement, sometimes also referred to as solar cell string. The solar cell arrangement may further comprise additional components such as external contacts via which the solar cell arrangement may be connected to an external electric circuit, such external contacts sometimes being referred to as forming part of a junction box. Furthermore, the solar cell arrangement may comprise for example bypass diodes or other electric components. Additionally, one or more release loops for releasing mechanical tensions may be included in the solar cell arrangement.

The solar cell arrangement is generally comprised in an encapsulation into which the solar cells, the electrical interconnections and possibly other components are embedded. Typically, the encapsulation comprises or consists of a thermoplastic polymer such as EVA (Ethylene Vinyl Acetate) or POE (Polyolefin Elastomer). The encapsulation may be composed of a front side polymeric lamination foil and a rear side polymeric lamination foil enclosing the plurality of solar cells from opposite sides. The lamination foils may also be referred to as encapsulation foils. In a lamination procedure, such front and rear side encapsulation foils may then be heated beyond a glassifying temperature of the polymeric material while being pressed against each other. Accordingly, the sticky viscous or even partially molten polymer material of both encapsulation foils may combine in regions where the foils contact each other and/or may glue to solar cells interposed between the encapsulation foils. Accordingly, upon cooling down and solidifying the polymer material, the solar cells and the polymer material of the lamination foils may form an encapsulation.

As the solar cell arrangement in its encapsulation is generally very fragile, the solar cell arrangement including the solar cells, the electric connections and the encapsulation is reinforced by one or more stabilisation foils for forming a PV label. Preferably, a front side polymeric stabilisation foil and a rear side polymeric stabilisation foil may enclose the interposed solar cell arrangement and may form a substrate and a superstate, respectively, prior to reinforcing the PV label by moulding the support structure. In specific embodiments, the PV label may not necessarily comprise the rear side polymeric stabilisation foil. The one or more polymeric stabilisation foils may have a thickness of typically between 250pm and 2500pm. Each of the foils may adjoin and/or cover a part or an entirety of one of opposing surfaces of all of the PV cells. The polymeric stabilisation foils may be made with various polymeric materials such as, polycarbonate (PC), polyethylenterephthalat (PET), polyamide (PA), polyetheretherketone (PEEK), Acrylonitrile butadiene styrene (ABS), Polymethyl methacrylate) (PMMA), Polyvinylchlorid (PVC) or a mix of them. At least the front side stabilisation foil as well as the front side lamination foil shall consist of an optically translucent or transparent material. Particularly, a material forming the stabilisation foil may be a thermoplastic material, i.e. a material which becomes plastic or viscous upon being heated to elevated temperatures. The front and rear side polymeric stabilisation foils may enclose the interposed solar cell arrangement and, upon being joined with each other, encapsulate the solar cell arrangement. Optionally, glass fiber reinforced or carbon fiber reinforced plastics may be included between the polymeric foils.

Particularly, the front side stabilisation polymeric foil, the rear side stabilisation polymeric foil and the PV cells may be joined together by an application of heat and/or a lamination process. In other words, after having arranged e.g. the rear side polymeric stabilisation foil, the solar cell arrangement with its encapsulation and finally the front side polymeric stabilisation foil on top of each other in a lose manner, these stacked layers may be interconnected by mechanically joining with each other. Such joining may be induced for example by applying sufficient heat to the stack such that the polymeric material of the polymeric foils becomes viscous and/or sticky.

Accordingly, upon such temporary application of heat, the polymeric stabilisation foils may mechanically interconnect with each other and/or with the interposed solar cell arrangement.

Thus, the front and rear side polymeric stabilisation foils and the solar cell arrangement are joined in a lamination procedure. The lamination procedure may be integral with the lamination procedure used for forming the encapsulation embedding the PV cells, i.e. both the front and rear side polymeric stabilisation foils as well as the front and rear side polymeric encapsulation foils may be glassified or partially molten within a single lamination step. Alternatively, two separate lamination steps may be performed, i.e., first, the solar cell arrangement is laminated with the encapsulation foils enclosing the PV cells and, then, the PV label is laminated with the stabilisation foils enclosing the solar cell arrangement in between. As a result of such lamination procedure, the front and rear side polymeric foils and, optionally, also the PV cells are integrally joined with each other in a positive substance jointing. However, the lamination procedure may alternatively or additionally include other measures for joining the polymeric foils such as for example applying a glue or adherent at an interface between the polymeric foils and/or at an interface between one of the polymeric foils and the solar cell arrangement. The entire PV label may have a thickness in a range of between 0.5 mm to 10 mm, typically between 0.5 mm to 5 mm or between 1 mm and 3 mm. Lateral dimensions of the PV label may range from about 0.1 m to 2 m, typically from 0.2 m to 1 m. The PV label may be flexible and bendable and may be formed into an arbitrary contour being adapted to a shape of the intended car body panel. Therein, the solar cells comprised in the car body panel cover a substantial portion, i.e. for example more than 30%, preferably more than 50% or even more than 70%, of an outer surface of the car body panel.

The PV label is generally flexible, bendable and/or, at least in some applications, not sufficiently self-supporting. Accordingly, for forming a self-supporting PV panel, the PV label generally has to be reinforced by a support structure. Such support structure typically has a higher mechanical stability than the PV label. Such higher mechanical stability may result, inter-alia, from larger geometrical dimensions such as a larger thickness compared to the thickness of the PV label and/or higher stiffness due to material properties of the polymer used. The support structure and the PV label are generally mechanically interconnected such that forces acting onto the PV label may be transmitted to the support structure and vice versa.

According to the approach described herein, the support structure shall be prepared with a mouldable thermosetting polymer. Such thermosetting polymer may be processed such that, during being applied to the PV label, it has a sufficiently low viscosity such as to enable spreading the thermosetting polymer along a surface of the PV label without exerting excessive forces onto the PV label.

For example, the thermosetting polymer may be a mixture of two or more components. At least one of these components may be a liquid having a low viscosity. For example, the viscosity at room temperature (25°C) may be below 1000 mPa*s, preferably below 300 mPa*s or even below 150 mPa*s. The components are adapted such as, upon being mixed with each other, a chemical reaction is initiated which results in a successive solidification of the mixture. In other words, upon being mixed, the components cure and solidify due to chemical reactions. However, initially, i.e. directly after having been mixed, the mixture of the components is highly fluid and may therefore easily be applied and spread along a surface of the PV label. Such application and spreading of the fluid polymer mixture may be done during a can-time (also referred to as potlife) of the mixture. Such can-time may be in a range of several seconds to several minutes. Typically, the can-time may be shorter than five minutes or shorter than one minute. The thermosetting polymer mixture then continuous solidifying until, after a demoulding time, being sufficiently solid for being self-supporting. The demoulding time may be typically more than a few minutes, for example more than ten minutes. The thermosetting polymer may then require another period of for example a few days until reaching a final solidification status. The thermosetting polymer may be based e.g. on a two-component polyurethane system. For example, the thermosetting polymer may be a mixture of polyol and isocyanate. It may contain glassfibres or carbonfibres for improving the material properties, as described in more details further below.

Alternatively, the thermosetting polymer comprise only one component and may be configured to cure and solidify upon energy being induced into the polymer. For example, such energy may be induced by heating the polymer beyond a specific curing temperature and/or by irradiating the polymer with energetic radiation such as UV-radiation.

The thermosetting polymer is applied to the rear surface of the PV label, i.e. to the surface which is directed away from light being incidents onto the PV label in normal operation. Optionally, the thermosetting polymer may also be applied to edges of the PV label. The thermosetting polymer may be spread along the entire rear surface of the PV label. Alternatively, the thermosetting polymer may be applied only onto partial areas of this rear surface.

For forming the support structure, the thermosetting polymer is applied onto the PV label in a vicious condition and is then formed into an intended shape of the panel by using a mould. In other words, in order to define a final shape of the support structure and of the entire panel, a mould is provided, the mould having a surface with a shape being complementary to the intended shape of the support structure. The mould may have a cavity, an inner surface of such cavity corresponding to the intended shape of the support structure. Accordingly, upon arranging the PV label in the cavity and filling the remaining volume of the cavity with the thermosetting polymer, the support structure supporting the PV label may be prepared. Alternatively, the mould may have a surface with the intended shape and may be pressed onto a thermosetting polymer mass which has been applied to the PV label in a preceding processing step, thereby forming and shaping the polymer. Upon the thermosetting polymer being formed and shaped in such manner, it may then solidify at least to a degree in which it is sufficiently stable and preferably self-supporting before being removed from the mould.

Specifically, the support structure is prepared by using a reaction injection moulding procedure including arranging the photovoltaic label in the mould, injecting the thermosetting polymer into the mould and removing the support structure formed upon solidifying the thermosetting polymer together with the photovoltaic label from the mould.

Reaction injection moulding (RIM) is a technique which is well established for producing for example large parts using low-cost tooling. Therein, a mould having a cavity is provided. The shape of the cavity corresponds to the shape of an intended moulded product. Similarly as in conventional injection moulding, a polymer being in a liquefied state is injected into the mould and is then solidified within the mould. However, in contrast to conventional injection moulding where a thermoplastic polymer is heated for being temporarily liquefied and then solidifies within the mould by cooling down, a thermosetting polymer is injected into the cavity of the mould. As such thermosetting polymer may generally have a substantially lower viscosity as compared to typical viscosities of a liquefied thermoplastic polymer, the thermosetting polymer may be injected in a RIM technology at substantially lower pressures as compared to pressures used in conventional injection moulding.

RIM is conventionally used for preparing products with a uniform polymeric material, i.e. the entire moulded product generally consists of the thermosetting polymer. Therein, the RIM is known to provide several advantages such as low-cost tooling, rapid production of the tooling, enabling the production of thin-walled components with varying wall thicknesses allowing sharp edges, short lead-times for large components, low capital investment, minimum setup requirements, cosmetic surface finishing, enabling processing of various polymer materials having positive physical characteristics such as being flame retardant or having high sheet deflection, etc. In some appliances, small parts such as pins, screws, brackets, etc. may be arranged within the cavity of the mould such as to be moulded into the polymer material and form part of the final product.

In the embodiment presented herein, it has been found that RIM may be beneficially used for preparing a support structure for a PV label in a way such that a risk of damaging the PV label and particularly the solar cells comprised therein is minimised. At the same time, using the RIM technology enables providing a very reliable, resistant, aesthetic and/or cost efficient PV panel. Optionally, the PV panel may have a curved surface and may serve for example as a vehicle body panel with PV integration. Furthermore, RIM may be specifically beneficial for integrating PV labels into solar panels, particularly into vehicle body panels, as it enables preparing thin walled structures and/or sharp edges.

According to an embodiment, the reaction injection moulding procedure includes at least one of the following characteristics:

- mixing at least two chemical components for preparing the thermosetting polymer, wherein the two chemical components are mixed immediately before injecting the thermosetting polymer into the mould;

- injecting the thermosetting polymer into the mould with a pressure of between 1 bar and 90 bar;

- injecting the thermosetting polymer into the mould with the thermosetting polymer having a temperature of between 18 °C and 60 °C.

Specifically, the thermosetting polymer may be prepared by mixing two or more chemical components. Accordingly, the thermosetting polymer may also be referred to as a reactive polymer. Therein, at least one first chemical component may act as a base material or matrix material, whereas at least one second chemical component may act as a binder material or hardener material. For example, the first chemical component may be polyol and the second chemical component may be isocyanate. The first and second chemical components may be stored separate from each other, for example in separate reservoirs, and may be brought together and mixed only immediately before injecting the thermosetting polymer generated thereby into the mould. Therein, the term “immediately” may be interpreted as relating to a time period within which the mixture obtained by mixing the at least two chemical components remain sufficiently liquid, i.e. remains at a low viscosity, for being easily injected into the mould. For example, the viscosity of the mixture should not increase within the time period being interpreted as being “immediately” by more than 20% relative, preferably not by more than 10% relative. For example, “immediately” may relate in this context to a time period being shorter than 1 min, preferably being shorter than 30 s shorter than 15 s or even shorter than 5 s.

Furthermore, the thermosetting polymer may be injected into the mould at pressures being preferably lower than 100 bar, i.e. lower than lOOOOkPa. Due to such injection at relatively low pressures, a risk of cell breakage in the PV label may be minimised. However, the thermosetting polymer should be injected into the mould at pressures being preferably higher than 30 bar, i.e. higher than 3000 kPa. With such sufficiently high injection pressures, the mould may be filled within a sufficiently short time period, thereby, inter-alia, increasing a throughput in a production procedure.

As a further characteristics, the thermosetting polymer may be injected into the mould while having a temperature of more than 18 °C, more preferably more than 25 °C. At such temperatures, chemical reactions between the chemical components comprised in the thermosetting polymer may solidify the thermosetting polymer within a sufficiently short time period, thereby, inter-alia, increasing the throughput in the production procedure. However, the injection temperature should preferably be lower than 60°C or lower than 40 °C, more preferably lower than 30°C. By avoiding excessively high injection temperatures, it may be avoided that the PV label is excessively heated upon coming into contact with the hot thermosetting polymer, thereby preventing damaging the PV label due to excessively high temperatures.

In an exemplary embodiment, the thermosetting polymer may be injected with an injection pressure of 6 bar +/- 2 bar at room temperature (i.e. 25 °C +/- 5°C). It may then solidify within a time period of 30 min +/- 10 min. In a subsequent tempering step, the thermosetting polymer may be heated to 50 °C +/- 10 °C for a time period of 6 h +/- 2 h and subsequently to 80 °C +/- 10 °C for a time period of 6 h +/- 2 h.

According to an embodiment, a layer of primer is applied onto the rear surface and, optionally to sides and/or edges of the photovoltaic label before applying the thermosetting polymer.

It has been observed that a support structure applied onto the rear surface of the PV label may suffer from insufficient adhesion unless the rear surface is specifically prepared in a preceding processing step before applying the mouldable polymer material thereon. In order to prevent such insufficient adhesion, a thin layer of a primer material may be applied to the rear surface of the PV label at least at those locations where the support structure is to be adhered to this rear surface.

The primer may be applied in liquid form. The primer may have a low viscosity. The primer may consist of or comprise an adhesion promoting material. The primer may be solvent-borne and/or pigmented. For example, the primer may be a prime coat comprising a solvent and being based on polyurethane. The primer may be configured for chemically reacting with humidity comprised in air in order to thereby cure or solidify. Initially, the primer may comprise a solid-state content and a solvent. The solid-state content may be for example between 10% and 50%, preferably between 20% and 40% or approximately 30% ± 5%. The primer may be specifically configured for enhancing adhesion to for example base surfaces or substrates comprising for example PMMA, PC (polycarbonate), PS (polystyrene), GFK, ABS, PVC or others. The primer may be applied onto the surface with simple tools such as a brush, a felt or a foam. The primer layer may be applied such as to have a thickness of preferably less than 1 mm or even less than 200 pm. The primer may have a flash-off time or airing time of between 1 min and 120 min, preferably between 5 min and 20 min. Excessively short flash-off times or excessively long flash-off times may negatively affect an adhesion induced by the primer. The primer layer may serve as an interface layer between the rear surface of the PV label and an adjacent surface of the support structure formed by the thermosetting polymer. The primer layer may provide a sufficient degree of elasticity. Accordingly, the primer layer may absorb or compensate slight motions between the PV label and the support structure, such motions occurring for example due to different thermal expansion coefficients of the materials of both components and therefore due to thermal stress.

According to an embodiment, the photovoltaic label is heated to an elevated temperature prior to arranging the photovoltaic label in the mould.

Upon being heated to such elevated temperature, the PV label obtains a higher deformability. Particularly, the polymeric stabilisation and lamination foils generally become more flexible and deformable at elevated temperatures. Due to such increased deformability, the PV label may be plastically deformed.

For example, the PV label may be deformed such as to obtain a pre-shaping in which the shape of the PV label is no more planar but is curved. Therein, the curved geometry of the PV label may, at least to a certain degree, correspond to an intended curved geometry of the final PV panel. Accordingly, mechanical tensions within the PV label, as they may result e.g. from thermal processing during laminating the various layers comprised in the layer stack forming the PV label, or mechanical tensions between the PV label and the support structure in the final PV panel may be reduced. Thereby, manufacturing the entire PV panel may be simplified as, for example, less warping is induced, particularly in producing large components. According to a further specified embodiment, the photovoltaic label is heated to an elevated temperature of between 50°C and 120°C, preferably of between 60°C and 110°C.

It has been observed that heating the PV label to more than 50°C or even more than 60°C may significantly enhance its deformability such as to enable pre-shaping the PV label. However, it has also been found that the PV label should not be heated to more than 120°C, preferably not more than 110°C, as damages may occur at the PV label at excessive temperatures. Particularly, the polymeric foils comprised in the PV label may suffer e.g. from reducing their adhesion to each other or even delaminations upon being excessively heated.

According to an embodiment, the mould comprises at least two moulding portions, wherein the photovoltaic label, when being in a first geometry, is arranged between the two moulding portions and the two moulding portions are then pressed together thereby plastically deforming the photovoltaic label into a second geometry.

In other words, the mould may comprise several moulding portions which may be moved relative to each other. For example, the mould may be opened by moving a first moulding portion away from a second moulding portion and may be closed by moving the first and second moulding portions towards each other. The PV label may initially be produced with its first geometry being planar. Such planar PV label may then be introduced into the opened mould and may be arranged between the two moulding portions. The PV label may be held, fixed or prefixed at one of the moulding portions using e.g. vacuum placing, pin placing or other techniques. In vacuum placing, the PV label is sucked towards a surface of the moulding portion by generating a vacuum or under pressure between both components. In pin placing, the PV label is pinned at a surface of the moulding portion. Furthermore, measures may be established for correctly positioning the PV label with respect to the moulding portion, i.e. for placing the PV label at an intended location relative to the moulding portion. Subsequently, the mould may be closed and the two moulding portions may be moved towards each other, thereby pressing onto the interposed PV label and deforming it into a nonplanar second geometry. This second geometry corresponds at least to a certain degree to the curved geometry of the intended PV panel. Preferably, the PV label is deformed plastically in such pressing action. This may preferably be achieved by heating the PV label to the elevated temperature as indicated further above. Particularly, the PV label may be heated before being inserted into the mould and being arranged between the two moulding portions. According to an embodiment, a layer of primer is applied onto the rear surface of the photovoltaic label after plastically deforming the photovoltaic label into the second geometry.

As described further above, such layer of primer may enhance an adhesion between the PV label and the support structure. It has been found to be advantageous to apply the primer not before but after any plastically deforming action for bringing the PV label into the curved second geometry. Particularly, it has been found to be advantageous to first heat the PV label to elevated temperatures and plastically deform the PV label in order to then, after the PV label having cooled down again, applying the layer of primer. Otherwise, the layer of primer could be deteriorated during any heating procedure and/or deformation procedure such as to lose at least partly its adhesion enhancing characteristics. For example, it should be avoided to heat the primer to elevated temperatures of for example more than 40°C before applying the thermosetting polymer onto it, as the primer may cure at such elevated temperatures and may therefore lose at least parts of its adhesion enhancing characteristics.

According to an embodiment, the photovoltaic label is arranged in the mould such that and the mouldable thermosetting polymer is applied such that the support structure formed by the thermosetting polymer engages with the photovoltaic label with an undercut structure.

In other words, the moulding procedure is specifically adapted such that the thermosetting polymer is not only applied to the rear surface of the PV label but is also arranged at positions where it engages the PV label with an undercutting geometry.

For example, the thermosetting polymer may also flow from the rear surface of the PV label around a circumferential rim of the PV label such as to cover at least a small surface area of the front surface of the PV label along its rim. Accordingly, the PV label is engaged between the portion of the polymer at its rear surface and the portion of the polymer at its front surface such that the positive joint or form closure is generated between the PV label and the support structure formed by the thermosetting polymer upon solidification. Due to such engagement with an undercut structure and the resulting form closure, the PV label is very reliably held at the support structure.

According to an embodiment, the mouldable thermosetting polymer comprises reinforcement fibres. The reinforcement fibres may extend within a bulk and/or along a surface of the support structure formed by the solidified thermosetting polymer. They may therefore reinforce its mechanical characteristics, particularly its strength and loadability and coefficient of thermal expansion (CTE). Its relative content can be varied such that the CTE matches to the CTE of the whole PV label and/or its individual layers and/or to the primer. For example, the reinforcement fibres may be thin glass fibres, carbon fibres, Kevlar fibres or similar. The reinforcement fibres may be provided as short fibres having the length of for example less than 0,1mm, preferably less than 0,05mm and/or as fibres having a length of for example more than 0,001mm, preferably more than 0,01mm. Particularly, short fibres may be similar to a powder, which is mixed into the thermosetting polymer, particularly e.g. into its polyol. Furthermore, the fibres may have a diameter of for example between 0,1 pm and 30 pm. A fibre content in the thermosetting polymer may be in a range of 1% to 50%, preferable a range of 10% to 30%.

According to an embodiment, the mould comprises a positioning arrangement such that, upon being arranged in the mould, the photovoltaic label is held by the positioning arrangement in a fixed position relative to the mould.

As indicated further above, RIM is conventionally generally used for producing products where the entire product consists homogeneously from a same polymer. However, in the approach described herein, while RIM may be applied for preparing the support structure, the entire product is to comprise the support structure together with the PV label. Accordingly, the PV label has to be arranged within the cavity of the mould during injecting the mouldable thermosetting polymer. As such injection of polymer tends to displace the PV label, it is suggested to provide the mould specifically with a positioning arrangement for keeping the PV label at a fixed position. Such positioning arrangement may comprise for example pins or other structures protruding into the inner volume of the cavity in the mould such as to locally support or hold the PV label at the intended position. Additionally or alternatively, the positioning arrangement may be configured for generating a vacuum or under pressure for sucking the PV label towards a surface of the mould and/or towards a pin, space or similar structure protruding from such surface. Such positioning arrangement or its protruding structures may be configured such that any motion of the PV label is restricted in at least one dimension, at least two dimensions or in all three dimensions. According to an embodiment, after solidifying the thermosetting polymer, the support structure is heated to an elevated tempering temperature.

After the thermosetting polymer has solidified, it is generally at a relatively low temperature such as ambient temperature. While, in such state, the produced PV panel has already its final geometry and structure, it may be beneficial to temporarily heat at least the support structure or, optionally, the entire PV panel to an elevated temperature. During such heating, the PV panel together with its support structure may get soft and deformable. Therefore, it may be held in place with a rig that doesn’t allow movement and should avoid permanent deformation or warpage of the part. Such heating procedure may also be referred to as tempering and the elevated temperature is referred to as tempering temperature. The tempering temperature may depend on characteristics of the thermosetting polymer and may typically be in a range of between 60°C and 140°C, preferably between 90°C and 125°C. Due to such final tempering, material characteristics of the thermosetting polymer may be modified such as to achieve for example a higher temperature resistance and/or rigidity. The tempering temperature may be maintained for a period of time of for example more than 60 min, preferably more than 120 min.

According to an embodiment, the proposed method further comprises applying a protection layer onto an outer surface of the panel after solidifying the thermosetting polymer.

The protective layer may be configured for protecting the PV panel or portions of its surface against mechanical, chemical and/or radiation influences. For example, the protection layer may provide UV absorption and may protect at least portions of the PV panel against UV radiation. Additionally or alternatively, the protection layer may provide superior rigidity such as to protect at least portions of the PV panel against scratching. For example, the protection layer may consist of an inorganic or an organic material. For example, the protection layer may consist of or comprise materials such as Polyurethane, Polyester, PVC. The protection layer may be applied using various techniques such as lacquering, foiling, evaporating, etc. The protection layer may be applied with a thickness being in a range of 0,01 mm - 0,2 mm, preferably in a range of 0,02 mm - 0,11 mm.

According to a further specified embodiment, the method additionally comprises, prior to applying the protection layer, applying a layer of primer onto the outer surface of the panel. In other words, a layer of primer may be applied before applying the protection layer in order to increase the adhesion of the protection layer at the outer surface of the panel. The layer of primer may have similar characteristics and may be applied in a similar manner as described further above for the layer of primer applied between the PV label and the polymer of the support structure. Prior to applying the layer of primer, the exposed surface of the PV label and/or the exposed surface of the support structure may be dragged or grinded. Thereby, this surface may be smoothed and/or its optical quality may be improved as, for example, unevenness or roughness typically initially being present in the PV label’s surface or the support structure’s surface may be planed and/or polished. Furthermore, adhesion of the primer may be improved thereby. Optionally, also the surface of the layer of primer may be dragged or grinded for, inter alia, improving an adhesion of the protection layer subsequently applied thereon.

Embodiments of the method described herein may be used for producing a PV panel in accordance with the second aspect of the invention. Therein, the PV panel comprises the PV label and the support structure of the solidified thermosetting polymer. Both components may be irreversibly connected to each other such as to form the PV panel as an integral unit. Such PV panel may have characteristics resulting from the production method. For example, the PV label may comprise the layer stack including various polymeric stabilisation and lamination foils with the interposed solar cell arrangement as described herein. Furthermore, the support structure may have characteristics typically arising upon forming the support structure from thermosetting polymer in a mould and subsequently solidifying the thermosetting polymer. Additionally, the PV panel may comprise a layer of primer interposed between the rear side of the PV label and the support structure. Furthermore, the PV panel may comprise a protection layer on top of an outer surface of the PV panel and, optionally, a layer of primer between such protection layer and the outer surface.

It shall be noted that possible features and advantages of embodiments of the invention are described herein partly with respect to a method of producing a PV panel and partly with respect to a PV panel producible with such method. One skilled in the art will recognize that the features may be suitably transferred from one embodiment to another and features may be modified, adapted, combined and/or replaced, etc. in order to come to further embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the following, advantageous embodiments of the invention will be described with reference to the enclosed drawings. However, neither the drawings nor the description shall be interpreted as limiting the invention.

Fig. 1 shows a reactive injection moulding device upon producing a PV panel in accordance with an embodiment of the present invention.

Fig. 2(a)-(e) visualise processing steps during producing a PV panel in accordance with an embodiment of the present invention.

The figures are only schematic and not to scale. Same reference signs refer to same or similar features.

DESCRIPTION OF PREFERRED EMBODIMENTS

Fig. 1 shows a reaction injection moulding device 101 with which a PV panel may be produced in accordance with an embodiment of the method proposed herein.

The RIM device 101 comprises a mould 103 including a lower moulding portion 105 and an upper moulding portion 107 enclosing a cavity 109. The cavity 109 has the shape of the PV panel to be produced. Such shape comprises curved surfaces.

In the cavity 109, the mould 103 comprises a positioning arrangement 111 including some protruding structures such as pins 113. Using such positioning arrangement 111, a PV label 3 may be precisely arranged and held at an intended position within the cavity 109 during an injection moulding procedure.

The RIM device 101 further comprises an introduction channel 115 discharging into a centre of the cavity 109. The introduction channel 115 connects the cavity 109 of the mould 103 with a mixer 117. A first fluid component comprised in a first reservoir 119 may be dozed via a first dosing device 121 into the mixer 117. A second component comprised in a second reservoir 123 may be dozed via a second dosing device 125 into the mixer 117. In the mixer 117, the first and second components are mixed to form a low viscosity mouldable thermosetting polymer which may then be introduced into the cavity 109 of the mould 103. Optionally, a reduced pressure or vacuum may be generated in the cavity 109 during injecting the polymer. Excessive air and/or gas caused by the reaction may escape from the cavity 109 via ventilation openings 127. As shown in the sequence depicted in figures 2(a) - (e), the PV panel 1 is produced by first preparing a PV label 3 (see figure 2(a)-(c)) and then preparing a support structure 17 attached to the PV label 3 (see figure 2(d)-(e)).

The PV label 3 comprises a front side polymeric stabilisation foil 5, a front side polymeric lamination foil 7, a rear side polymeric lamination foil 9 and a rear side polymeric stabilisation foil 11. A solar cell arrangement 13 comprising several rigid wafer-based solar cells 15 is interposed between the front and rear side polymeric lamination foils 7, 9, which themselves are interposed between the front and rear side stabilisation foils 5, 11- The entire stack of polymeric foils 5, 7, 9, 11 including the solar cell arrangement 13 is laminated to form the PV label 3. Initially, this PV label 3 is prepared with a planar first geometry (see figure 2(a)).

Subsequently, the PV label 3 is heated to an elevated temperature of for example 70 - 90°C. At such elevated temperature, the polymeric foils 5, 7, 9, 11 come increasingly deformable.

In such heated state, the PV label 3 is introduced into the mould 103 for a first time. Therein, the PV label 3 may be fixed using the positioning arrangement 111. Particularly, the PV label 3 is interposed between the lower moulding portion 105 and the upper moulding portion 107 and the two moulding portions 105, 107 are then pressed together. Thereby, the PV label 3 is deformed into a curved second geometry. This second geometry at least roughly corresponds to a contour of the cavity 109 of the mould 103 and therefore to the contour of the PV panel 1 to be produced (see figure 2(b)).

Subsequently, a first layer 19 of primer is applied onto the rear surface 4 of the PV label 3 (see figure 2(c)). Therein, the primer is preferably deposited onto the rear surface 4 upon the PV label 3 being cooled down to ambient temperatures.

Then, the PV label 3 is introduced into the mould 103 for a second time. Again, the PV label 3 may be positioned using the positioning arrangement 111. Upon the lower and upper moulding portions 105, 107 of the mould 103 being closed with the PV label 3 being arranged in the cavity 109, mouldable thermosetting polymer is introduced into the cavity 109 via the introduction channel 115. Due to its low viscosity, such thermosetting polymer may easily spread throughout the cavity 109 without being excessively pressurised and may cover portions of the rear surface 4 or the entire rear surface 4 of the PV label 3. The thermosetting polymer may then solidify and thereby form the support structure 17 (see figure 2(d)).

Particularly, the cavity 109 of the mould 103, the shape of the PV label 3 and the manner in which the PV label 3 is arranged within the mould 103 may be specifically configured such that at least a small portion of the thermosetting polymer may flow around a rim 25 of the PV label 3 to the front side 6 of the PV label 3. Thereby, an undercut structure 27 forming a positive joint between the PV label 3 and the support structure 17 may be formed.

For example, the PV label 3 may have a step structure 29 along its rim 25. Such step structure 29 may result for example from using a rear side polymeric stabilisation foil 11 which has slightly larger dimensions than the front side polymeric stabilisation foil 11. Upon being suitably held within the cavity 109 of the mould 103, the thermosetting polymer may then flow around the rim 25 of the PV label 3 and fill an empty space in such step structure 29 in a way such that, finally, the solidified polymer forms the undercut structure 27 with the PV label’s step structure 29 while forming a flush surface or a smooth transition between an outer surface of the support structure 17 and an outer surface of the PV label 3.

Alternatively, the rim 25 of the PV label may be formed with a slanted, bevelled or chamfered edge geometry. Again, polymer may then flow around such rim 25 and form the undercut structure 27 with the PV label’s edge geometry.

After solidification of the thermosetting polymer to a sufficient degree such as to become mechanically stable and self-supporting, the entire PV panel 1 including the PV label 3 and the support structure 17 is removed from the mould 103.

Subsequently, the PV panel 1 and particularly its support structure 17 is heated to a tempering temperature of for example more than 100°C or even up to 125°C.

Then, a second layer 21 of primer is applied to the front surface 6 of the PV panel 1. Such second layer 21 may be applied in an area including the exposed surface of the PV label 3 as well as a surface of a portion of the support structure 17 forming the undercut structure 27 and covering the PV label 3 along its rim 25 at the front side 6 of the PV label 3. On top of such second layer 21 of primer, a protection layer 23 is then deposited, such protection layer 23 serving as a protection against UV radiation and/or protection against scratching (see figure 2(e)).

The resulting PV panel 1 may be specifically configured such as to form a car body panel. Such car body panel generally has a three-dimensional curved outer contour. Using the approach described herein, high- efficiency photovoltaics including wafer-based solar cells may be easily and reliably integrated into such car body panel.

Upon the thermosetting polymer being sufficiently solidified, the final product forming the PV panel 1 including the PV label 3 together with the support structure 17 formed by the solidified polymer may be removed from the mould 103. Therein, upon opening the mould 103, the final product has to be demoulded from the moulding portions 105, 107. In order to enable a corresponding demoulding process, a surface of the respective moulding portion 105, 107 defining the cavity 109 may have to be pre-treated before injecting the thermosetting polymer. Such pre-treatment may include covering the respective surface with a demoulding agent. However, applying such demoulding agent may require an additional process step. Furthermore, the demoulding process may bear a risk of temporarily deforming the PV panel 1, thereby risking breakage of solar cells 15 in its PV label 3. In order to, inter-alia, simplify the demoulding process and/or reduce a risk of solar cell breakage, the surface of the lower moulding portion 105 and/or the surface of the upper moulding portion 107 defining the cavity 109 may be made with or may be covered by a silicone material, thereby forming a silicone layer with very low adherence characteristics and/or with elastic deformability. Such layer may have a thickness of between 1 mm and 10 mm. For example, a flexible silicone mattress may be disposed on top of the respective surface. Upon removing the final PV panel 1 from the mould 103, such mattress may be easily detached from the abutting surface of the PV panel 1. Accordingly, pre-treating the inner surface of the respective moulding portion(s) 105, 107 and, particularly, applying any demoulding agent may be dispensable, thereby simplifying the entire moulding procedure. Furthermore, a risk of solar cell breakage upon closing the mould 103 may be reduced as the silicone layer is generally elastically deformable and may therefore absorb excessive local pressures acting onto e.g. the PV label 3 and its included solar cells 15 and/or distribute such local pressures onto a larger surface. Furthermore, it has been observed that the PV label 3 may frequently comprise some variations regarding its thickness. Alternatively or additionally, the PV label 3 may comprise some waviness. Conventionally, the mould 103 and the moulding procedure established therewith may generally not be able to compensate such thickness variations and/or waviness. As a result, excessive local pressures may act onto the PV label 3 and may provoke breakage of solar cells 15 comprised therein. In order to overcome or relax such problem, the mould 103 may be provided with at least one sealing lip at one of its surfaces at the lower moulding portion 105 or the upper moulding portion 107. Upon preparing the support structure 17, the PV label 3 may then be disposed on top of such sealing lip and an underpressure or vacuum may be generated between the PV label 3 and the respective surface of the moulding portion 105, 107, thereby sucking the PV label 3 towards the respective surface. As a result of such suction, the PV label may be pressed against the associated inner surface of the respective moulding portion 105, 107 and may be pressed into a curved geometry or contour corresponding to the form of such inner surface. Upon subsequent injection of the thermosetting polymer into the cavity 109 at the other side of the PV label 3, the cavity 109 may be completely filled with thermosetting polymer while compensating any waviness and/or thickness variations of the PV label 3. After solidification of the thermosetting polymer, an outside surface of the PV label 3 may therefore perfectly correspond to the predefined 3D contour of the inner surface of the respective lower moulding portion 105, i.e. may not show any waviness.

Furthermore, it has been found that, upon preparing the support structure 17 in the moulding procedure, some local areas of the PV label 3 may have to be prevented from being covered with the thermosetting polymer. For example, a non-covered area may be required at the rear side of the PV label 3 in order to enable attaching and electrically connecting a connection box or junction box to the PV label 3. Such non-covered area may be generated by intentionally not covering the respective area with the first layer of primer 19 such that no thermosetting polymer may locally adhere to the PV label 3. However, in such cases, the first layer of primer 19 has to be applied to the PV label 3 with very high accuracy. Particularly in cases, where such first layer of primer 19 is applied manually by a technician, the technician may have problems in precisely determining areas of the PV label 3 where primer is to be applied and areas where no primer should be applied. If excessive primer is applied, thermosetting material then adhering to the PV label in an area which should remain non-covered may have to be removed after the moulding procedure, therefore possibly requiring additional manual work. If insufficient primer is applied, no thermosetting material may adhere to the PV label 3 in areas which need to be supported by the support structure 17. It is therefore suggested to, before applying the primer for forming the first layer 19 of primer, specifically marking the area of the PV label 3 which shall remain noncovered. Such marking may be established using for example a laser. Additionally, for example a polarity of a connection to be applied to the PV label 3 may be marked with the laser and may be visible after completion of the production procedure.

Embodiments of the method and device described herein may be used for various appliances. For example, PV integrated vehicle body panels may be provided. For example, PV panels forming an outer cover of a vehicle body, a vehicle roof element, a battery cover of e.g. an electric bus or a bus shoulder at an upper portion of a bus may be provided. As a specific example, for example a PV integrated tonneau or lid for covering e.g. a cargo area of a truck may be provided. As a further example, a PV integrated and potentially movable or deployable roof component for a campervan may be provided.

Finally, it should be noted that the term “comprising” does not exclude other elements or steps and the “a” or “an” does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

LIST OF REFERENCE SIGNS

1 PV panel

3 PV label

4 rear surface of PV panel

5 front side polymeric stabilisation foil

6 front surface of PV panel

7 front side polymeric lamination foil

9 rear side polymeric lamination foil

11 rear side polymeric stabilisation foil

13 solar cell arrangement

15 solar cell

17 support structure

19 first layer of primer

21 second layer of primer

23 protection layer

25 rim of the PV label

27 undercut structure

29 step structure

101 reaction injection moulding device

103 mould

105 lower moulding portion

107 upper moulding portion

109 cavity

111 positioning arrangement

113 pin

115 introduction channel

117 mixer

119 first reservoir

121 first dosing device

123 second reservoir

125 second dosing device

127 ventilation opening

Claims

1. Method for producing a photovoltaic panel (1), particularly a photovoltaic car body panel, the method comprising: providing a photovoltaic label (3) comprising a front side polymeric stabilisation foil (5), a front side polymeric lamination foil (7), a rear side polymeric lamination foil (9) and, optionally, a rear side polymeric stabilisation foil (11) as well as a solar cell arrangement (13) interposed between the front and rear side lamination foils (7, 9), preparing a support structure (17) for supporting the photovoltaic label, wherein the support structure is prepared by applying a mouldable thermosetting polymer to at least a rear surface (4) of the photovoltaic label, wherein the support structure is prepared by applying the thermosetting polymer in a viscous condition using a reaction injection moulding procedure, including forming the thermosetting polymer into an intended shape of the panel using a mould (103) by arranging the photovoltaic label in the mould and injecting the thermosetting polymer into the mould and solidifying the thermosetting polymer before removing the support structure formed upon solidifying the thermosetting polymer together with the photovoltaic label from the mould.

2. Method according to claim 1, wherein the reaction injection moulding procedure includes at least one of the following characteristics:

- injecting the thermosetting polymer into the mould with a pressure of between Ibar and 80 bar;

- injecting the thermosetting polymer into the mould with the thermosetting polymer having a temperature of between 18°C and 60°C. Method according to one of the preceding claims, wherein a layer (19) of primer is applied onto the rear surface and, optionally, to sides and/or edges of the photovoltaic label before applying the thermosetting polymer. Method according to one of the preceding claims, wherein the photovoltaic label is heated to an elevated temperature prior to arranging the photovoltaic label in the mould. Method according to claim 4, wherein the photovoltaic label is heated to an elevated temperature of between 50°C and 120°C, preferably of between 60°C and 110°C. Method according to one of the preceding claims, wherein the mould comprises at least two moulding portions (105, 107), wherein the photovoltaic label being in a first geometry is arranged between the two moulding portions and the two moulding portions are then pressed together thereby plastically deforming the photovoltaic label into a second geometry. Method according to claim 6, wherein a layer (19) of primer is applied onto the rear surface of the photovoltaic label after plastically deforming the photovoltaic label into the second geometry. Method according to one of the preceding claims, wherein the photovoltaic label is arranged in the mould such that and wherein the mouldable thermosetting polymer is applied such that the support structure formed by the thermosetting polymer engages with the photovoltaic label with an undercut structure (27). Method according to one of the preceding claims, wherein the mouldable thermosetting polymer comprises reinforcement fibres. Method according to one of the preceding claims, wherein the mould comprises a positioning arrangement (111) such that, upon being arranged in the mould, the photovoltaic label is held by the positioning arrangement in a fixed position relative to the mould. Method according to one of the preceding claims, wherein, after solidifying the thermosetting polymer, the support structure is heated to an elevated tempering temperature. Method according to one of the preceding claims, further comprising applying a protection layer (23) onto an outer surface of the panel after solidifying the thermosetting polymer. Method according to claim 12, wherein, prior to applying the protection layer, a layer (21) of primer is applied onto the outer surface of the panel. Photovoltaic panel (1), particularly a car body panel, the panel including: a photovoltaic label (3) comprising a front side polymeric stabilisation foil (5), a front side polymeric lamination foil (7), a rear side polymeric lamination foil (9) and, optionally, a rear side polymeric stabilisation foil (11) as well as a solar cell arrangement (13) interposed between both lamination foils (7, 9), and a support structure (17) for supporting the photovoltaic label, wherein the support structure includes a solidified thermosetting polymer being prepared using a reaction injection moulding procedure and being attached to at least a rear surface of the photovoltaic label (3). Photovoltaic panel according to claim 14, the photovoltaic panel is being produced using the method according to one of claims 1 to 13.