WO2025031732A1 - Photovoltaic composite panel and manufacturing method - Google Patents

Abstract

A photovoltaic composite panel (100), is presented and comprises at least one photovoltaic module (102), a fibre reinforced rear composite sheet (104) spanning the entire panel (100), and a fibre reinforced front composite sheet (106) with essentially the same outer dimensions as the rear composite sheet (104) and a thickness matching a thickness of the photovoltaic module (102), wherein the front composite sheet (106) features at least one recess (108) matching the at least one photovoltaic module (102), wherein the photovoltaic module (102) is arranged in the recess (108) and a sun face (112) of the photovoltaic module (102) is aligned with a front face (114) of the front composite sheet (106), wherein the rear composite sheet (104) and a rear face (116) of the front composite sheet (106) are bonded together, and the rear composite sheet (104) and a rear face of the photovoltaic module (102) are bonded together. Furthermore, a method for manufacturing a photovoltaic composite panel (100) is presented.

Description

Sono Motors GmbH

Photovoltaic composite panel and manufacturing method

FIELD OF THE INVENTION

The present invention relates to a photovoltaic composite panel and to a method for manufacturing such photovoltaic composite panels.

TECHNICAL BACKGROUND

In the following, the term “photovoltaic” may be abbreviated by “PV”. PV cells may also be referred to as solar cells. The term “panel” may refer to a panel which may be included in and/or attached to a body of any kind of vehicles such as cars, trucks, trailers, busses, mobile homes, trains, ships, airplanes, etc.

Most commercially available PV modules for vehicles are arranged on a surface of the vehicle, in particular, the modules are attached, e.g., glued, to the surface. The surface and underlying structures of the vehicle are essentially carriers for the modules.

Such PV modules protrude from the surface and for example raise a drag of the vehicle and/or create corners on the surface, where dirt can accumulate.

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.

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. Further approaches for a car body panel comprising an integrated solar cell arrangement have been proposed by the present applicant in earlier patent applications WO 2022/122507 Al and DE 10 2022 101 935 Al, the latter one describing a use of reaction injection moulding techniques for PV panel production. 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 WO 2021/260021 Al (title: “Method for fabricating a photovoltaic module including laser cutting of a photovoltaic label”), WO 2021/260024 Al (title: “Method for fabricating a curved photovoltaic module including adapted positioning of photovoltaic cells”) and DE 10 2022 108 014 Al (title “Method for fabricating a Photovoltaic Module using In-Mould Labelling with specific Temperature Management”). Another approach for a car body panel comprising an integrated solar cell arrangement has been proposed by the present applicant in earlier patent application WO 2022/122507 Al, having the title “Car body panel including a solar cell arrangement and method for producing same”. Furthermore, EP 22 189 888 Al discloses a connector for a PV panel in a vehicle.

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

Nevertheless, the development and production of these PV sandwich panels, particularly PV integrated vehicle cladding sandwich panels, still has several challenges such as a limited size of the panels, due to a limited size of injection moulding tools and/or material characteristics of the used polymers limiting a maximum bridged length. Overall, the PV sandwich panel should be producible on an industrial scale, at low costs and/or with high reliability.

SUMMARY OF THE INVENTION AND OF EMBODIMENTS

In the following, a PV composite panel, particularly a PV integrated vehicle cladding composite panel, and a method for manufacturing the same are disclosed, which may achieve at least some of the above-mentioned desired characteristics. According to a first aspect of the present invention, a photovoltaic composite panel is disclosed, comprising at least one photovoltaic module, a fibre reinforced rear composite sheet spanning the entire panel, and a fibre reinforced front composite sheet with essentially the same outer dimensions as the rear composite sheet and a thickness matching a thickness of the photovoltaic module, wherein the front composite sheet features at least one recess matching the at least one photovoltaic module. The photovoltaic module is arranged in the recess and a sun face of the photovoltaic module is aligned with a front face of the front composite sheet. The rear composite sheet and a rear face of the front composite sheet are bonded together. The rear composite sheet and a rear face of the photovoltaic module are also bonded together.

According to a second aspect of the present invention, a method for manufacturing a photovoltaic composite panel according to the first aspect is presented. The method includes at least the following steps, not necessarily in the indicated order:

- arranging the recess and the photovoltaic module relative to each other such that the photovoltaic module is accommodated within the recess, wherein a sun face of the photovoltaic module and a front face of the front composite sheet are aligned,

- bonding the rear composite sheet and a rear face of the front composite sheet together and bonding the rear composite sheet and a rear face of the photovoltaic module together.

Briefly summarized 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: Due to the inventive combination of two bonded sheets of fiber reinforced composite material, one of them being a continuous sheet, the other having recesses for PV modules with PV modules arranged inside and also bonded to the continuous sheet, a rigid top layer for an extended lightweight sandwich panel may be achieved. Therein, while each of the individual PV modules may have a small size and/or a standardized size, the entire PV composite panel may be a large sized and its size may for example be specifically adapted to a particular application case. For example, the entire PV composite panel may comprise a multiplicity of standard-sized PV modules being mechanically combined with each other by intermediate portions of the front composite sheet and/or by the entirely covering rear composite sheet such as to form a large entity which may cover for example an entire roof or sidewall of a large trailer.

In the following, possible features of embodiments of the invention and associated possible advantages will be described in more detail. A fiber reinforced material may be a composite material. The fiber reinforced material may comprise at least two different bonded components. One component may be a stable matrix. The other component may be reinforcing fibers. One component may be embedded in and/or bonded to the other component. The components may have different characteristics. Fibers may have a high tensile strength. The matrix may have a high pressure resistance. The characteristics of both components may complement each other in the reinforced material.

Fibers may be industrial fibers, like carbon, glass, UHMW-PE or aramid fibers, or natural fibers, like hemp, flax, wood, bamboo, sisal, or nettle fibers. The matrix may be a cured resin. The resin may be a thermoset resin, like epoxy, polyester, vinyl ester, or polyurethane. The resin may also be a thermoplastic resin, like PP, PET, PC or PS. The fiber and/or resin may be treated or comprise additives to achieve desired characteristics, like fire resistance, water resistance, UV- resistance and/or oxidation resistance.

A recess may be referred to as a recess, a pocket, an indentation, an interruption, a perforation, or any kind of recess through the whole or partial thickness of one sheet. A shape of the recess may correspond to a shape of a PV module. In other words, dimensions and/or a contour of the recess may substantially be equal or slightly larger (i.e., for example at most 5 millimeters larger) than dimensions and/or a contour of the PV module to be accommodated therein. Multiple recesses may be spaced apart by ribs, fillets, or strips of composite material. The recesses may be arranged in a regular pattern. The PV modules may be arranged in the recesses with their photosensitive side facing out.

Generally, a PV module may be from any technology available.

Particularly, the approach proposed herein is particularly suitable for a PV-integrated (vehicle body) panel comprising multiple PV cells being interposed between polymeric foils and forming a solar cell arrangement. Due to their small thickness of typically less than 1 cm, in many cases less than 5 mm, the PV modules comprised in such panel may also be referred to as PV labels. Therein, the PV cells may be 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 or connection 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), Polyvinylchloride (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 fibre reinforced, or carbon fibre reinforced plastics may be included between the polymeric foils.

Particularly, the front side stabilisation polymeric foil, the rear side stabilisation polymeric foil, the lamination foils 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 module or 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. 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%, more than 70% or even more than 90%, of an outer surface of the PV composite panel. The entire PV composite panel may include multiple PV modules, i.e. for example more than 3, more than 5, more than 10 or even more than 20 PV modules. The entire PV composite panel may have large dimensions with a width of e.g. more than 1 m or more than 2 m and a length of more than 1 m, more than 2 m, more than 3 m, more than 5 m or even more than 10 m.

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 material 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.

In the present case, the support structure is mainly formed by the front and rear composite sheets which are bonded to the PV module and/or to each other. Bonding of two surfaces may be achieved by applying an uncured resin or glue to at least one surface, arranging the surfaces on top of each other and applying pressure and/or heat to let the resin or glue set and cure. The resin may be similar to the resin used in the composite material. The resin or glue may also be of a different category, to achieve a desired curing time, surface wetting, cohesion and/or adhesion.

The term “sun face” is defined as the side of a PV module which is dedicated to being directed towards the sun when the PV module is in action of producing energy. Rear face is the opposite direction to this sun face. Front face of the sheet is the same direction as the sun face.

Aligned faces may create a continuous surface with minimum height offset. The aligned faces may be essentially in the same plane. In other words, the aligned faces may be flush with each other.

To align the sun face of the photovoltaic module and the front face of the front composite sheet, the sun face of the photovoltaic module and the front face of the front composite sheet may be arranged on an even surface of a tool for manufacturing the panel. The front face and the sun face may be aligned to each other by the surface. The tool may be coated with a release agent before the PV module and the front composite sheet are arranged on the surface. The photovoltaic module may be arranged on the surface first and the front composite sheet may be arranged around the photovoltaic module. Alternatively, the recess may be kept free by using a placeholder shaped like the PV module.

The front face of the front composite sheet may be formed by a protective layer. A protective layer may provide protection against external influences, like environmental stress. Particularly, the protective layer may have a high UV resistance, high wear resistance and/or smooth surface against dirt adherence. The protective layer may be a gelcoat or another resin. The protective layer may also be a foil or film. The foil or film may be made from metal or a polymer.

The recess may be cut out of at least one prefabricated continuous layer of composite material to tailor the front composite sheet. In particular, the prefabricated continuous layer of composite material may comprise multiple layers, including the protective layer and at least one fibre reinforced layer. A continuous layer may be easily manufactured or acquired from commercial sources. Prefabricated material is easy to handle. Side faces of the photovoltaic module and side faces of the recess may be bonded together by a sealant arranged between the side faces of the photovoltaic module and the side faces of the recess. The recess in the prefabricated continuous layer of composite material may be slightly bigger than the PV module. A resulting gap may be sealed with sealant. The sealant may be applied from the front side of the panel after bonding the rear composite sheet to the front composite sheet and the PV module, or from the rear face of the front composite sheet before the rear composite sheet is bonded to the front composite sheet and the PV module.

Alternatively, the front composite sheet may be manufactured in place and layers of the front composite sheet may be stacked on the surface of the tool excluding the recess. The photovoltaic module may be arranged on the surface first and the layers may be arranged around the photovoltaic module. Alternatively, the layers may be arranged around a placeholder. The protective layer and at least one fibre reinforced layer of the front composite sheet may be stacked and bonded together to build up the thickness of the front sheet to match the thickness of the photovoltaic module. For example, the protective layer may be arranged on the surface of the tool and the fibre reinforced layer may be stacked on top of the protective layer. In particular, the fibre reinforced layer may be stacked on top of the protective layer, when the protective layer is in a semi-cured state, to assure adhesion between the layers. Stripes or rovings of reinforcing fibre material and resin may be arranged around the PV module or the placeholder until the thickness of the PV module is reached. The reinforcing fibre material and resin may be put down separately and the fibre material wetted in place. The reinforcing fibre material may also be preimpregnated with resin. Pre-impregnated layers may be referred to as prepregs. With prepregs in particular, the recess may be cut out of at least one continuous layer of prepreg to tailor the layer. Fibre orientation may vary between layers.

Side faces of the photovoltaic module and side faces of the recess may be bonded together. The side faces of the PV module may be wetted with resin during the manufacturing process of the front composite sheet. The resin may adhere to the PV module and bond the PV module to the front composite sheet.

An electrical connection of the photovoltaic module may be arranged between layers of the panel and lead to a side face of the panel. The electrical connection may comprise at least two wires, cables, or vanes. The connection may be bonded in between the front composite sheet and the rear composite sheet. The connection may alternatively be arranged on the backside of the rear composite sheet.

A lightweight core structure may be bonded between a rear face of the rear composite sheet and a backside cover sheet of the panel. The photovoltaic composite panel may be used as a front panel of a sandwich panel. A sandwich panel may be used as a sidewall or roof of a vehicle, like a trailer, an RV or a commercial truck. A lightweight core may be a foam, a honeycomb structure, or a corrugated structure from different materials. A backside cover sheet may be a composite sheet like the rear composite sheet. The backside cover sheet may be similar to the rear composite sheet to get a sandwich panel with homogenous properties. Alternatively, the backside cover sheet may be of a different material like plastic, metal, or wood.

It shall be noted that possible features and advantages of embodiments of the invention are described herein partly with respect to a PV composite panel, partly with respect to specific applications thereof and partly with respect to a method for manufacturing such PV composite panel. 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 schematically shows a cross-sectional view of a photovoltaic composite panel according to an embodiment.

Fig. 2 schematically shows a top view of a photovoltaic composite panel according to an embodiment.

Fig. 3 schematically shows a cross-sectional view of a photovoltaic sandwich panel with a photovoltaic composite panel according to an embodiment.

Fig. 4 schematically shows a detail of a cross-sectional view of an electrical connection of a photovoltaic composite panel according to an embodiment. Figs. 5 to 10 schematically show steps of a method for manufacturing a photovoltaic composite panel according to an embodiment of the invention.

Fig. 11 schematically shows a front composite sheet for a photovoltaic composite panel according to an embodiment.

Fig. 12 schematically shows a cross-sectional view of a photovoltaic composite panel according to an embodiment.

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

DESCRIPTION OF PREFERRED EMBODIMENTS

In the following, some exemplary embodiments of a photovoltaic sandwich panels 1 are described in detail.

Fig. 1 schematically shows a cross-sectional view of a photovoltaic composite panel 100 according to an embodiment. The photovoltaic composite panel 100 comprises two photovoltaic modules 102, a rear composite sheet 104 spanning the entire panel 100 and a front composite sheet 106 with two recesses 108 for the two photovoltaic modules 102. The recesses 108 are separated by a part 110 of the front composite sheet 106. The front composite sheet 106 is as thick as the photovoltaic modules 102. The recesses 108 intersect the whole front composite sheet 106, so that a sun face 112 of the photovoltaic modules 102 is aligned with a front face 114 of the front composite sheet 106. The rear composite sheet 104 is bonded with a rear face 116 of the front composite sheet 106 and rear faces of the photovoltaic modules 102. As the rear composite sheet 104 has end-to-end reinforcing fibres, the rear composite sheet stiffens the photovoltaic composite panel 100 considerably. In addition, the parts 110 of the front composite sheet 106 between the photovoltaic modules 102 act as stiffening ribs and increase an overall stiffness of the photovoltaic composite panel 100.

In an embodiment, the front composite sheet 106 comprises multiple layers. The front face 114 is formed by a protective layer 118. At least one layer 120 of composite material is bonded to the protective layer 118. The layers 120 are bonded by a resin or bonding agent 122. Here, the layer 120 is thick enough, to bring an overall thickness of the front composite sheet 106 to a thickness of the photovoltaic modules 102.

Fig. 2 schematically shows a top view of a photovoltaic composite panel 100 according to an embodiment. The photovoltaic composite panel 100 essentially corresponds to the photovoltaic composite panel in Fig. 1. In contrast, here the photovoltaic composite panel 100 has five photovoltaic modules 102 arranged in a row. The photovoltaic composite panel 100 may be used as an outer layer of a roof of a trailer or a box body of a commercial truck, for example.

Each photovoltaic module 102 is separated from the next photovoltaic module 102 by a strip shaped part 110 of the front composite panel 106. The photovoltaic modules 102 have an oblong rectangular shape and long sides of the photovoltaic modules 102 are separated by the strip shaped parts 110. The photovoltaic composite panel 100 also has an oblong rectangular shape. Short sides of the photovoltaic modules 102 are parallel to a long side of the photovoltaic composite panel 100. For example, short sides of the photovoltaic composite panel 100 are as long, as a width of the trailer or truck. The long sides of the photovoltaic composite panel 100 are as long, as a length of the trailer or the box body. The photovoltaic modules 102 are arranged along a long axis of the photovoltaic composite panel 100. Due to the predetermined size of the photovoltaic panels 102, a marginal strip 200 of the front composite sheet 106 along the long sides of the photovoltaic composite panel 100 is slightly wider than along the narrow sides of the photovoltaic composite panel 100 and wider than the parts 110 of the front composite sheet 106 between the photovoltaic modules.

In an embodiment, electrical connections 202 lead to a side face 204 of the photovoltaic composite panel 100.

Fig. 3 schematically shows a cross-sectional view of a photovoltaic sandwich panel 300 with a photovoltaic composite panel 100 according to an embodiment. The photovoltaic composite panel 100 essentially corresponds to the photovoltaic composite panel in Figs. 1 or 2. Here, a lightweight core structure 302 is bonded to a rear face 304 of the rear composite sheet 104. A backside cover sheet 306 is bonded to the core structure 302 and completes the photovoltaic sandwich panel 300. The photovoltaic sandwich panel 300 may be used as a structural body part, like a sidewall or a roof of a trailer, truck, recreational vehicle, or mobile home. The core structure 302 adds thickness to the photovoltaic composite panel 100 and improves the section modulus of the photovoltaic sandwich panel 300. The core structure 302 may be a foam material or a honeycomb or corrugated structure.

In an embodiment, the backside cover sheet 306 is also a fibre reinforced sheet and corresponds to the rear composite sheet 104. This way, the photovoltaic sandwich panel 300 has a homogenous structure and can withstand high loads.

In an embodiment, the photovoltaic sandwich panel 300 is manufactured in the same tool as the photovoltaic composite panel 100.

Fig. 4 schematically shows a detail of a cross-sectional view of an electrical connection 202 of a photovoltaic composite panel 100 according to an embodiment. The photovoltaic composite panel 100 essentially corresponds to the photovoltaic composite panel in Figs. 1 or 2. The electrical connection 202 is arranged between the sheets 104, 106 and leads to the side face 204 of the photovoltaic composite panel 100. An alternative embodiment that is not shown in Fig. 4 may provide the electrical connection 202 arranged on the backside of the rear sheet 104.

In an embodiment, the electrical connection 202 is arranged between layers of the front composite sheet 106. The electrical connection 202 is bonded between the layers. An alternative embodiment that is not shown may provide the electrical connection 202 arranged on the backside of the rear composite sheet 104 and core structure 302.

Figs. 5 to 11 schematically show steps of a method for manufacturing a photovoltaic composite panel according to an embodiment of the invention. The photovoltaic composite panel essentially corresponds to the photovoltaic composite panel in Figs. 1 or 2. The photovoltaic composite panel is manufactured inside a simple tool 500. The tool 500 requires a flat, even surface 502. The tool 500 may have a surrounding rim 504. The tool 500 is easily scalable to fit a desired panel size. First, the front composite sheet 106 is created.

In Fig. 5 the photovoltaic modules 102 are arranged on the surface 502 with their sun faces 112 towards the surface 502. The photovoltaic modules 102 are arranged with gaps 506 between them. The photovoltaic modules 102 will create the recesses 108 in the front composite sheet. Here, two photovoltaic modules 102 are used, for example. The photovoltaic modules 102 define a thickness of the front composite sheet. The surface 502 may be treated with a release agent before putting on the photovoltaic modules 102. Alternatively, placeholders for the photovoltaic modules 102 may be arranged on the surface 502.

In Fig. 6 a first layer of the front composite sheet is arranged on the surface 502 of the tool 500. As the first layer, a protective layer 118 is arranged in the gaps 506 and around the photovoltaic modules 102 or placeholders. The protective layer 118 will form the front face 114 of the first composite sheet and will protect the photovoltaic composite panel 100 from environmental stresses. The protective layer 118 may be a gelcoat, for example.

In Fig. 7, a bonding agent 122 is arranged on the protective layer 118. In the case of the protective layer 118 being gelcoat, the bonding agent 122 is spread on the protective layer, before the gelcoat 118 has completely cured and is still sticky.

In Fig. 8, stripes 800 of reinforcing fibre material are arranged on and/or in the bonding agent 122, wetting them with the bonding agent 122. The stripes 800 in combination with the bonding agent 122 form at least one other layer of the front composite sheet. The stripes 800 are as wide, as the gaps 506, respectively a margin between a side of the tool 500 and the adjacent photovoltaic module 102 or placeholder. The stripes 800 are stacked as high, as the photovoltaic modules 102 and fill the gaps 506 to build up the desired thickness of the front composite sheet 106. Alternatively, the fibre material is chosen with a thickness that brings an overall thickness of the front composite sheet 106 to a thickness of the photovoltaic modules 102. The front composite sheet 106 is now complete.

In an alternative embodiment, in Figs. 7 and 8, preimpregnated reinforcing fibre material is cut to size and arranged on the protective layer 118 to create the front composite sheet 106. The preimpregnated reinforcing fibre material is preimpregnated with the optimum amount of bonding agent and prevents accumulations of liquid bonding agent. The preimpregnated reinforcing fibre material may be referred to as prepregs. The prepregs may be used as stripes or as complete layers with the recesses 108 cut out of them.

In Fig. 9, bonding agent 122 is applied to the rear face 116 of the front composite sheet and rear faces of the photovoltaic modules 102 in preparation for bonding the rear composite sheet to the front composite sheet 106. In Fig. 10, the rear composite sheet 104 is arranged on the whole rear face 116 of the front composite sheet 106 and the rear faces of the photovoltaic modules 102. The rear composite sheet 104 spans the entire panel 100. The reinforcing fibre material goes from one side face 204 of the rear composite sheet 104 to the other side face 204. The rear composite sheet 104 may be prefabricated and cured. The hardened rear composite sheet 104 is bonded to the rear faces 116 of the front composite sheet 106 and the photovoltaic modules 102 by the bonding agent 122. The rear composite sheet 104 may alternatively be built up in place by wetting the reinforcing fibre material in the bonding agent 122.

Alternatively, the rear composite sheet 104 may be made of at least one continuous prepreg. Then the dispensing of the bonding agent is not necessary.

Fig. 11 schematically shows a front composite sheet 106 for a photovoltaic composite panel according to an embodiment. The front composite sheet 106 is cut from a prefabricated fibre reinforced wafer with the correct thickness. At least the recesses 108 are cut out of the wafer.

In an embodiment, the wafer already has the necessary protective layer.

Fig. 12 schematically shows a cross-sectional view of a photovoltaic composite panel 100 according to an embodiment. The photovoltaic composite panel 100 essentially corresponds to the photovoltaic composite panel in Figs. 1 or 2. Here, the front composite layer is prefabricated and 106 corresponds to the front composite layer in Fig. 11. The photovoltaic modules 102 and the recesses 108 are arranged to each other. The recesses 108 are slightly larger than the photovoltaic modules 102. A resulting gap between side faces of the photovoltaic modules and side faces of the recesses 108 is filled with a sealant 1200.

The rear composite sheet 104 is bonded to the rear faces of the photovoltaic modules and the front composite sheet 106 like described in Fig. 10.

In the following, possible embodiments of the invention are again summarized or presented with a slightly different choice of words.

A method for producing a composite panel with integrated photovoltaic is presented. Sandwich panels are often used for building different parts used in construction of transportation vehicles, including, passenger cars, recreational vehicles, cargo-boxes, and trailers. These vehicles are increasingly becoming partially or completely electrically driven. In addition, the use of electric devices implemented inside such vehicles is also growing. Hence, the interest for including solar modules on the body part of vehicles is expanding.

A short-term solution is to stick PV modules on the body parts, which is the state of the art for vans and RVs. However, many OEMs prefer to have the PV modules integrated into the body parts for a better quality, better aesthetics, extended lifetime, and higher security.

Composites are very often used as face-sheet for producing sandwich panels in combination with lightweight cores. There are PV modules with composite frontsheet and backsheet. However, the size of such PV modules does not allow for a thorough coverage of large sandwich panels. Furthermore, such modules are limited in size and, e.g., in the case of a big trailer box, many of such modules would need to be bound together for covering the surface.

Another method is to laminate PV modules on a composite sheet, i.e., using the composite sheet as the backsheet of the module. This method has many advantages but also comes with size limitation. The size of such composite PV modules, and accordingly the sandwich panel produced thereof, is limited to the size of the PV lamination machine. Such machines are limited in size. Although very large lamination machines are theoretically plausible, in practice they will be too costly and complex for construction.

The approach presented here is to produce composite sheets with integrated off-the-shelf photovoltaic modules. The composite sheet with integrated PV modules can be eventually used for producing a sandwich panel.

An embodiment of a proposed procedure sequence comprises:

Applying the release-agent to the inner surface of the tool. The tool is covered by a release agent for easy demoulding.

Positioning the PV modules in the tool. One or several PV modules, depending on the size and design of the tool and modules, are positioned in the tool with their sunny face down, i.e., the sunny face touching the surface of the tool. Modules can be fixed to their position by some kind of temporary adhesive or by vacuum suction.

Applying the protective coating. In the gap between PV modules, and the gap between the modules and the wall of the tool, a protection coating, such as gelcoat is applied. This coating will be the utmost exterior component of the composite sheet or later the sandwich panel. The role of this layer is to protect the sandwich panel from environmental stresses.

Applying the bonding agent. Before reaching the complete gelation time of the gelcoat, when the gelcoat is neither completely cured and hard nor fresh and liquid, but in a gel state in between, which can take few minutes to few hours, a bonding agent such as a resin, a glue or a coupling paste is applied in the gaps between the PV modules.

Positioning composite stripes. Right after applying the bonding agent, stripes of composite, which are cut to the size of the gaps between PV modules, are positioned in the gaps between the PV modules. The thickness of the composite stripes is chosen so that they level with the height of the PV modules after positioning to create a flat surface.

Applying the bonding agent. A bonding agent, which can be a resin, a glue, or similar, is applied on the backside of the composition, i.e., composite stripes and PV modules. To avoid irregularities and obtain a flat surface, the bonding agent can be mixed with filling agents, such as fibres.

Positioning the whole composite sheet. Right after applying the bonding agent, a final composite sheet is placed on the whole composition, which will cover the whole surface of the tool. At this stage the whole stack will be pressed together, and if necessary, heated up. Curing of the bonding agent will create a solidified stack.

Demoulding of the stack. After enough time for curing, which take several minutes to several hours, the solidified stack can be demoulded.

Fig. 2 shows a final part with e.g., five integrated modules.

The composite material can have a thickness of 0.1 to 10.0 mm, preferably 0.3 to 5.0 mm, ideally 0.5 to 2.0 mm. Reinforcement fibres are preferably made of glass, but other materials such as carbon or different types of natural fibre such as flax, wood, kenaf bamboo, etc. are also possible to use. The binding matrix can be made of thermoset resin such as, polyester, vinyl ester, epoxy and polyurethane, or thermoplastic resins such as PP, PET, styrinics and PC. The resin and the fibre can be modified/treated with different chemicals for improved performance in e.g., fire resistance, humidity absorption, weathering resistance, oxidation resistance, etc.

The PV modules used here are ready to use and do not require any further protection or coating. The modules can be from any technology.

The electrical connection of the PV modules can happen from the sunny side of the module. It can also happen from the back side of the module, in which case, it is necessary to drill or machine openings in the composite sheet for access. It is also possible to have the connection from the sides/edge of the module as shown in Fig. 4.

The composite stripes and sheet can be directly bought from many suppliers in the market with the suitable size and properties in form of sheets or a role. Properties include size, thickness, materials, surface quality (surface treatment) for an easy adhesion, etc. the process can be done wet on wet as described. Another possibility is that after finishing the front composite sheet the composition can be put under press and temperature to cure, and then followed by the steps to add the rear composite sheet.

The process of positioning strips can take place as explained in Fig.8. It is also possible, in case the size of the raw composite sheets allows, to cut windows/pockets in the size of PV modules out of a large composite sheet and use such a perforated sheet instead of composite stripes, as shown in Fig. 11.

If the required size of the PV integrated composite or sandwich panel allows the use of the composite window illustrated Fig 11, one can avoid the steps to build up the front composite sheet. The used readymade front composite sheet can already possess a protective layer and have the same thickness as the PV module. Such composites sheets are for example used for building RVs. Here, a sealing material may be used to seal the gap between the PV modules and the composite window, which can be applied before applying the bonding agent or after demoulding.

In all the above cases, a tempering step can happen. In an embodiment, the composites stripes and sheet can be replaced by pre-impregnated fibres (woven, non-woven, unidirectional) with partially cured resin, generally known as prepreg. By using prepregs, no bonding agent is necessary. The composition then can be cured in or out of an autoclave.

The final product, i.e., PV modules integrated in composite can be demoulded and be used as is, or it can be used in a conventional sandwich panel manufacturing processes as the external facesheet. Another method for producing a sandwich panel is through the described steps, followed by direct building of the sandwich panel inside the available tool.

The core material may be any core material used in the industry, including honeycombs from different materials, corrugated cores, foams, etc. The internal face-sheet of the sandwich panel may be a similar material as the used composite stripes and sheet for the photovoltaic composite panel to get homogeneous properties in the whole sandwich composition. However other facesheets such as composites sheets of different composition or of sheets from different material such a plastics, metals or wood may also be used.

With the presented approach, theoretically any off-the-shelf PV module may be used for integration, as well as any kind of composite sheet, if they fulfil the design requirements. Furthermore, the size of the photovoltaic composite panel is not limited to the size of the laminator. The size of the photovoltaic composite panel is only limited by the size of the tool, which is considerably less complex than a laminator. Such tools exist in dimensions which are substantially larger than commercially available PV laminators.

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

100 PV composite panel

102 PV module

104 rear composite sheet

106 front composite sheet

108 recess

110 part

112 sun face

114 front face

116 rear face

118 protective layer

120 layer

122 bonding agent

200 strip

202 electrical connection

204 side face

300 PV sandwich panel

302 core structure

304 rear face

306 cover sheet

500 tool

502 surface

504 rim

800 stripe

1200 sealant

Claims

1. Photovoltaic composite panel (100), comprising: at least one photovoltaic module (102), a fibre reinforced rear composite sheet (104) spanning the entire panel (100), and a fibre reinforced front composite sheet (106) with essentially the same outer dimensions as the rear composite sheet (104) and a thickness matching a thickness of the photovoltaic module (102), wherein the front composite sheet (106) features at least one recess (108) matching the at least one photovoltaic module (102), wherein the photovoltaic module (102) is arranged in the recess (108) and a sun face (112) of the photovoltaic module (102) is aligned with a front face (114) of the front composite sheet (106), wherein the rear composite sheet (104) and a rear face (116) of the front composite sheet (106) are bonded together, and the rear composite sheet (104) and a rear face of the photovoltaic module (102) are bonded together.

2. Photovoltaic composite panel (100) according to claim 1, wherein the front face (114) of the front composite sheet (106) is formed by a protective layer (118).

3. Photovoltaic composite panel (100) according to claim 2, wherein the protective layer (118) and at least one fibre reinforced layer (120) of the front composite sheet (106) are stacked and bonded together.

4. Photovoltaic composite panel (100) according to one of the preceding claims, wherein an electrical connection (202) of the photovoltaic module (102) is arranged between layers (120) of the panel (100) and leads to a side face (204) of the panel (100), or the electrical connection (202) of the photovoltaic module (102) is arranged on the backside of the rear composite sheet (104)

5. Photovoltaic composite panel (100) according to one of the preceding claims, wherein side faces of the photovoltaic module (102) and side faces of the recess (108) are bonded together.

6. Photovoltaic composite panel (100) according to claim 5, wherein the side faces of the photovoltaic module (102) and the side faces of the recess (108) are bonded together by a sealant (1200) arranged between the side faces of the photovoltaic module (102) and the side faces of the recess (108).

7. Photovoltaic composite panel (100) according to one of the preceding claims, wherein a lightweight core structure (302) is bonded between a rear face (304) of the rear composite sheet (104) and a backside cover sheet (306).

8. Photovoltaic composite panel (100) according to one of the preceding claims, wherein the photovoltaic module (102) comprises wafer-based silicon solar cells.

9. Method for manufacturing a photovoltaic composite panel (100), the photovoltaic composite panel (100) comprising: at least one photovoltaic module (102), a fibre reinforced rear composite sheet (104) spanning the entire panel (100), and a fibre reinforced front composite sheet (106) having essentially the same outer dimensions as the rear composite sheet (104) and a thickness matching a thickness of the photovoltaic module (102), the front composite sheet (106) having at least one recess (108) matching the at least one photovoltaic module (102), the method comprising:

- arranging the recess (108) and the photovoltaic module (102) relative to each other such that the photovoltaic module (102) is accommodated within the recess (108), wherein a sun face (112) of the photovoltaic module (102) and a front face (114) of the front composite sheet (106) are aligned,

- bonding the rear composite sheet (104) and a rear face (116) of the front composite sheet (106) together and bonding the rear composite sheet (104) and a rear face of the photovoltaic module (102) together.

10. Method according to claim 9, wherein to align the sun face (112) of the photovoltaic module (102) and the front face (114) of the front composite sheet (106), the sun face

sheet (106) are arranged on a surface (502) of a tool (500) for manufacturing the panel (100).

11. Method according to claim 10, wherein layers (200) of the front composite sheet (106) are stacked on the surface (502) excluding the recess (108).

12. Method according to claim 11, wherein a protective layer (118) of the front composite sheet (106) is arranged on the surface (502) of the tool (500) to form the front face (114) of the front composite sheet (106), wherein at least one layer (200) of composite material is stacked on the protective layer (118) to build up the thickness of the front sheet (106) to match the thickness of the photovoltaic module (102).

13. Method according to one of claims 10 to 12, wherein the photovoltaic module (102) is arranged on the surface (502) first and the front composite sheet (106) is subsequently arranged around the photovoltaic module (102).

14. Method according to one of the claims 9 to 13, wherein the recess (108) is cut out of at least one prefabricated continuous layer of composite material to tailor the front composite sheet (106).