Method of making a building panel and the panel

Abstract

The invention relates, among other things, to a method of making a thin panel (10) for outdoor applications, comprising, among other things, the following steps: a) providing a deep-drawable film (10) of a transparent plastic, b) deep-drawing the film (11) in a mold (34), c) mounting a structure (19) having solar cells (32) on an inner face (16) of the deep-drawn film (12), d) placing the deep-drawn film (12) with mounted structure (19) in a cavity (33) of a mold (34) having in particular at least two mold halves (13, 14), e) introducing a liquid polyurethane casting compound (24) into the cavity (33) of the mold (34) and spreading the polyurethane casting compound (24) over an inner face (18) of the structure (19) and/or over the inner face (16) of the film (12), f) curing the polyurethane casting compound, in particular with the mold closed, to form a reinforcement layer (30), or comprising the following steps j) and k) instead of the steps e) and f): j) introducing a granular particle foam mass into the cavity (33) of the mold (34) and spreading over an inner face (18) of the structure (19) and/or over the inner face (16) of the film (12), k) baking and curing the particle foam mass, in particular with the mold closed, to form a reinforcement layer (30).

Claims

1. A method comprising the following steps: a) providing a deep-drawable film of a transparent plastic, b) deep-drawing the film, c) mounting a structure having solar cells on an inner face of the deep-drawn film with an inner face of the structure turned away from the film and an outer face of the structure on or closely juxtaposed with the inner face of the film, d) placing the deep-drawn film with the mounted structure in a cavity of a mold having at least two mold halves, e) introducing foamable granular particles into the cavity of the mold and spreading the granular particles over the inner face of the structure in direct contact with the inner face of the structure without the interposition of an adhesive, f) heating the mold and thereby conductively heating and foaming the granular particles in the cavity into a foam mass, g) curing the foam mass with the mold closed to form a reinforced panel, and h) removing the reinforced panel from the mold.

2. The method according to claim 1, wherein the film consists of polycarbonate or PMMA.

3. The method according to claim 1, further comprising the step of: gluing the outer face of the structure on the inner face of the deep-drawn film.

4. The method according to claim 1, wherein before step e) the following step is performed: i) introducing a liquid barrier layer casting compound of polyurethane into the cavity of the mold and spreading the barrier layer casting compound over the inner face of the structure or over the inner face of the film, the granular particles being subsequently spread in step e) over the liquid barrier layer.

5. The method according to claim 1, wherein before step e) the following step is performed: i) introducing a liquid in-mold-paint casting compound into the cavity of the mold and spreading the in-mold-paint casting compound over the inner face of the structure or over the inner face of the film, the foamable granular particles being subsequently spread in step e) over the casting compound.

6. The method according to claim 5, wherein the step i) is performed after the step of: j) introducing a liquid barrier layer casting compound of polyurethane into the cavity of the mold and spreading the barrier layer casting compound over an inner face of the structure or over an inner face of the film.

7. The method according to claim 1, wherein the steps b) and d) and e) are performed in the same mold.

8. The method according to claim 1, wherein the step b) is carried out in a first mold and steps d) and e) are performed in a second mold and the deep-drawn film is passed from the first mold to the second mold after the step b) to perform the steps d) and e).

9. The method according to claim 1, further comprising the step of: providing electrical lines connected to the structure.

10. The method according to claim 9, wherein at least a section of the lines passes through the foam mass.

11. The method according to claim 10, wherein the foam mass has a passage for the electrical lines.

12. The method according to claim 1, further comprising the step of: using the reinforced panel as an exterior panel for cars, commercial vehicles, trailers, or agricultural machines, or as a roof element, a side wall element, an engine hood, a trunk lid, a fender or a trim part for a vehicle.

13. The method according to claim 1, further comprising the step of: using the panel after removal from the mold as a vehicle exterior body part.

Description

(1) Further advantages of the invention become apparent from the non-cited subclaims and with reference to the following description of the embodiments illustrated in the drawings. Shown are:

(2) FIG. 1 schematically, in a partially sectioned view, a deep-drawable film before the deep-drawing operation,

(3) FIG. 2 in a partially sectioned representation, a mold having lower mold and upper mold and the film of FIG. 1 deep-drawn in the mold, wherein the mold is shown open, and the deep-drawn film is shown slightly spaced from the lower mold,

(4) FIG. 3 the deep-drawn film of FIG. 2 in a single representation with structure having solar cells mounted to the inner face thereon,

(5) FIG. 4 the deep-drawn film with mounted structure in an open mold, having a lower mold and an upper mold, wherein a mixing head is moved schematically shown in a cavity of the opened mold, which mixing head dispenses a liquid polyurethane casting compound and distributes on the inner face of the deep-drawn film and on the inner face of the structure,

(6) FIG. 5 the finished made panel, still located in the closed mold form after the curing of the casting compound,

(7) FIG. 6 in a partially sectioned, schematic, enlarged detailed view approximately according to partial circle VI in FIG. 5, a connecting region of deep-drawn film, solar cell and reinforcement layer,

(8) FIG. 7 in detailed representation, the finished panel made and removed from the mold form,

(9) FIG. 8 a representation according to FIG. 7, a further embodiment of a panel according to the invention with an electrical supply line connected to the structure,

(10) FIG. 9a in an enlarged detailed view, approximately according to partial circle IX in FIG. 8, a tied-down region of the electrical supply lines to the solar cells and the passage in the reinforcement layer,

(11) FIG. 9b a further embodiment of a panel according to the invention in a representation analogous to FIG. 9a, wherein in this embodiment, a channel is provided for the passage of electrical lines to the solar cells in the deep-drawn film,

(12) FIG. 10 in an enlarged detailed representation according to partial circle X in FIG. 7, the layer structure of a panel made according to the invention,

(13) FIG. 11 in a representation according to FIG. 10, the layer structure of a further embodiment of the panel according to the invention,

(14) FIG. 12a in a representation according to FIG. 10, the layer structure of a further embodiment of the panel according to the invention,

(15) FIG. 12b in a representation according to FIG. 10, a further embodiment in which the layer structure of the panel has an in-mold-paint casting compound and a barrier layer casting compound,

(16) FIG. 13 in a representation according to FIG. 10, the layer structure of a further embodiment of the panel according to the invention,

(17) FIG. 14 in a simplified, schematic representation, a container into which an unfoamed granular particle foam mass is filled,

(18) FIG. 15 in a schematic representation similar to FIG. 14, the container and additionally a schematically shown foaming device, in particular in the form of an infrared oven, wherein the unfoamed granular particles of FIG. 14 are configured partially foamed or finally foamed and with respect to the representation of FIG. 14, have significantly increased volumes,

(19) FIG. 16 a further embodiment of the invention in a representation according to FIG. 4, wherein the deep-drawn film with structure mounted thereto already described based on the previous embodiments is arranged in an opened mold and is inserted into the lower mold, wherein the mold is opened, and the upper mold is spaced from the lower mold, and wherein a granular particle foam mass consisting of foamed particles is introduced into the cavity of the mold, and is spread over the inner face of the deep-drawn film and over the inner face of the structure,

(20) FIG. 17 the embodiment of FIG. 16 in a representation according to FIG. 5, wherein the finished made panel still in the closed mold form is shown after the curing of the granular particle foam mass, wherein for explanation, additionally with respect to the representation of FIG. 5, heating is indicated that tempers the mold, and

(21) FIG. 18 in a representation according to FIG. 7, the finished made panel of FIG. 17 that is removed from the mold form in a detailed representation.

(22) Embodiments of the invention are described by way of example in the following description of the figures, also with reference to the drawings. For reasons of clarity, identical or comparable parts or elements or regions are also designated with the same reference numerals, sometimes with the addition of small letters, even if different embodiments are involved.

(23) Features which are described only in relation to one embodiment can also be provided in the context of the invention in any other embodiment of the invention. Such modified embodiments are comprised by the invention, even when they are not shown in the drawings.

(24) All disclosed features are essential to the invention. In the disclosure of the application, the disclosure content of the associated priority documents (copy of the prior application) and the cited references and the described devices of the prior art are hereby incorporated in full, also for the purpose, to include individual or multiple features of these documents in one or more claims of the present application.

(25) First, the family of embodiments according to FIGS. 1 to 13 are explained according to a first aspect of the invention. These are embodiments which are finished by performing steps e) and f) of claim 1, and require corresponding methods.

(26) The panel according to the invention is designated by the reference numeral 10 in the drawings as a whole.

(27) Such a panel is shown in the finished made state in FIG. 7 in a solo representation. The panel consists of different layers 12, 19, 30 that are explained in detail later. It should first be pointed out that the panel 10 is configured altogether planar and therefore has a total wall thickness GW which is significantly smaller than the width B of the panel 10. The length L of the panel in a direction transverse to the plane of the paper of FIG. 7 lies in the order of magnitude of the width B and is thus also considerably larger than the total wall thickness GW.

(28) The width B and the length L can be, for example, 5 to 1000 times the total wall thickness GW.

(29) To manufacture the panel 10 according to FIG. 7, the procedure is as follows:

(30) Starting from FIG. 1, a deep-drawable film 11 is first provided. This has a wall thickness W1 (FIG. 10) which, for example, is between 0.1 mm and 10 mm, preferably between 0.5 mm and 3 mm. The deep-drawable film 11 consists of a transparent, that is, see-through material which allows transmission of at least certain spectral ranges of the electromagnetic radiation spectrum emitted by the sun. In particular, polycarbonate or PMMA is considered as a material for the deep-drawable film 11.

(31) The deep-drawable film 11 is inserted into a mold having a lower mold 13 and an upper mold 14 according to FIG. 2. As a result of a closing operation of the mold, the film 11 can be deep-drawn and reach its deep-drawn mold 12 shown in FIG. 2. In this case, the film is deformed as a result of the deep-drawing operation.

(32) The invention also comprises deep-drawing steps, in which, the shaping of the deep-drawable film 11 is achieved as a result of a blow molding operation, starting from a planar state that lies flat, into the desired three-dimensional shape. The mold 13 can be tempered for this purpose, and for example, suction devices can be present to pull up the outer side 15 of the deep-drawable film 11 to the inner face 36 of the lower mold 13. In such deep-drawing operations that take place in the manner of blowing operations, an upper mold 14 is not or not necessarily mandatory.

(33) FIG. 2 shows a half-opened state of the mold, in which the upper mold 14 is spaced from the lower mold 13.

(34) The deep-drawn film 12 is shown, for illustrative purposes only, slightly spaced from the lower mold 13.

(35) Subsequently, according to a variant of the invention, the deep-drawn film 12 can be removed from the mold. In another variant of the invention, the deep-drawn film 12 can remain in the lower mold 13.

(36) In a further step, a structure 19 having solar cells 32 is now mounted to the inner face 16 of the deep-drawn film 12.

(37) The structure 19 can consist exclusively of solar cells 32, or can comprise solar cells 32. The structure 19 can be provided as a handling unit. In particular, it can be configured as a planar element that can possibly also be conformable to the contour of the inner face 16 of the deep-drawn film 12. The structure 19 can be provided as an adhesive film. In a variant of the invention, the structure 19 can be a composite panel which, in addition to the actual solar cells 32 serving to generate electricity, also comprises plastic panels, carrier materials, substrates or the like on which the solar cells 32 are mounted.

(38) In the simplest case, the structure 19 is mounted to the inner face 16 of the deep-drawn film 12 by means of a gluing operation. For this purpose, the outer side 17 of the structure 19 can be provided with an adhesive layer and/or the inner face 16 of the deep-drawn film 12 can be provided with a corresponding adhesive layer. Alternatively, it is also possible for the structure 19 to be overlaid or covered on its outer side 18 by a carrier material which overlaps the structure 19 on the outer side and is glued to the inner face 16 of the film 12.

(39) The invention also comprises when the mounting of the structure 19 to the deep-drawn film 12 is carried out only for the purpose of achieving a kind of pre-assembly state, so that position retention is achieved only for a short period of time. In one variant of the invention, it is therefore sufficient if the structure 19 is only placed on the inner face 16 of the deep-drawn film for a short time.

(40) According to a further method step, which is explained with reference to FIG. 4, a liquid polyurethane casting compound 24 is mounted to the deep-drawn film 12 with structure 19 mounted thereto. This is carried out according to the invention in a mold 34 that further advantageously comprises a lower mold 13 and an upper mold 14.

(41) In one variant of the invention, the mold 34 can be the same mold shown in FIG. 2, in which the deep-drawing operation has already been performed. In this case, it is not necessary in a variant of the invention that the deep-drawn film 12 is ever removed from the lower mold 13. Also, the mounting of the structure 19 can be carried out directly, with deep-drawn film 12 remaining in the lower mold 13.

(42) In a variant of the invention, the deep-drawn film 12 is removed from the mold shown in FIG. 2 after the deep-drawing operation and has been passed into the mold 34 in FIG. 4 and has been introduced into the cavity 33 of the mold 34 shown there. An mounting of the structure 19 to the deep-drawn film 12 can be carried out in a cavity 33 of the mold 34 in this embodiment, or in a further variant of the invention, even outside the mold 34. In the last-mentioned variant, the deep-drawn film 12, with the structure 19 mounted thereto, can be passed from an external location on which the structure 19 has been mounted to the film 12, to the mold 34 of FIG. 4.

(43) FIG. 4 shows the state in which the deep-drawn film 12 with the structure 19 mounted thereto is inserted into the lower mold 13.

(44) According to the invention, a mixing head 20 is provided, to which liquid polyurethane casting compound is supplied via a supply line 21, optionally also supplying reinforcing fibers.

(45) A mixture of the polyol panel and the isocyanate panel preferably is carried out only in the mixing head.

(46) To avoid repetition, reference is made to the Applicant's numerous patent applications mentioned above, which explain this mixing operation and the chemical processes in detail.

(47) The mixing head 20 is, as indicated schematically by the movement direction arrow 23, movable over the inner face 16 of the deep-drawn film 12 or over the inner face 18 of the structure 19. A discharge device 22 is assigned to the mixing head 20, with which discharge device the liquid polyurethane casting compound 24 can be dispensed. FIG. 4 shows a state in which only a partial section of the inner face 16, 18 of the deep-drawn film 12 and structure 19 is glazed or wetted with liquid polyurethane molding compound.

(48) The introduction operation of the liquid polyurethane casting compound 24 is completed when a substantially full-surface application is achieved. The invention also comprises when, depending on the adjustment of the viscosity of the polyurethane casting compound 24, an independent, at least partial flow of the liquid polyurethane casting compound 24 also is carried out over the inner face 16, 18 in the course of the introduction operation.

(49) According to the invention, the mold 34 is subsequently closed and the upper mold 14 moved toward the lower mold 13 for this purpose, so that a closed cavity is formed.

(50) Under the action of pressure and temperature, the polyurethane casting compound foams within a predetermined reaction time and forms a cured reinforcement layer 30. The volume of the cured reinforcement layer 30 is considerably greater than the volume of the introduced polyurethane casting compound 24.

(51) Preferably, foaming and curing are carried out with the mold closed.

(52) FIG. 5 shows a state in which the reinforcement layer 30 is configured finished, the polyurethane casting compound 24 is thus cured.

(53) The detailed representation according to FIG. 6 depicts in the edge region, the size ratios of the individual layers, only schematically and by way of example.

(54) The structure 19 can extend with its edge region 37 up to near the edge region 38 of the deep-drawn film 12.

(55) On the other hand, the invention also comprises embodiments in which large distances lie between the edge region 38 of the deep-drawn film 12 and the edge region 37 of the structure 19 containing solar cells 32.

(56) As shown in FIG. 7, the panel 10 thus formed can now be removed from the mold form. FIG. 7 illustrates separation edges 25a, 25b, along which a separation of overhang regions 39a, 39b can be carried out. The overhang regions 39a, 39b are due to the manufacturing method and take into account, for example, that overhangs must be provided for purposes of mold sealing during deep-drawing.

(57) The layer structure of the finished panel 10 according to FIG. 7 can be seen in the partial circle illustration of FIG. 10. Clearly visible are the different wall thicknesses W1 of the deep-drawn film 12, W2 of the structure 19 and W3 of the reinforcement layer 30.

(58) The reinforcement layer 30 stiffens the panel as a whole, so that this is configured to be completely rigid and can be used in a conventional manner, such as a vehicle part, despite the large width B and the large length, not shown, L and the very small total wall thickness GW.

(59) According to a variant of the invention, which is illustrated in FIG. 11, a layer is provided between the structure 19 and the reinforcement layer 30 that is referred to as barrier layer 27. Such a barrier coat is provided by a barrier layer casting compound which is mounted to the inner face 16 of the deep-drawn film 12 or to the inner face 18 of the structure 19 before the polyurethane casting compound 24 is introduced. It is preferably provided that the barrier layer casting compound 27 is cured before the polyurethane casting compound 24 is introduced.

(60) The barrier layer 27 can advantageously serve to avoid a view by an observer of the reinforcement layer 30 from the outer side of the finished made panel 10. Therefore, no structures of the reinforcement layer 30 can be seen on the surface.

(61) In particular, when, as shown in the embodiment of FIG. 13, reinforcing fibers 29a, 29b, 29c are provided in the liquid polyurethane casting compound 24, for example, as short or long fibers, these fiber structures can not be seen by the presence of the barrier layer 27 on the surface.

(62) According to a further advantageous embodiment of the invention, as shown in FIG. 12a, it is provided that an in-mold-paint layer 28 is arranged between the structure 19 with the solar cells 32 and the reinforcement layer 30. This is an application of paint, that is, a type of varnish which is mounted to the inner face 16 of the deep-drawn film 12 or on the inner face 18 of the structure 19. This varnish forms an in-mold paint layer 28. Advantageously, an application is carried out on the inner face 16 of the deep-drawn film 12 and on the inner face 18 of the structure 19, before the liquid polyurethane molding compound 34 is mounted. In addition, it is advantageously provided that the in-mold-paint layer 28 first cures before the polyurethane casting compound 24 is mounted.

(63) In a further embodiment, not shown, the layer structure of the panel 10 comprises an in-mold-paint layer 28 and additionally a barrier layer 27. Such an embodiment is shown in FIG. 12b.

(64) According to a further embodiment of the invention, it is now explained as seen in FIGS. 8, 9a and 9b that the structure 19 having solar cells 32 can also have electrical connection lines 26a, 26b:

(65) FIG. 9a makes schematically clear that the structure 19 has solar cells 32. For the sake of clarity, only a single solar cell 32 in the form of a planar module is shown. This is only to be understood schematically: The structure 19 can consist entirely of solar cells 32, or can comprise a plurality of such solar cells 32. However, the structure 19 can also have a carrier material or a matrix for the solar cells 32.

(66) It is clear to the person skilled in the art that the electromagnetic radiation obtained by the solar cells 32 has to be led away via lines 26a, 26b after conversion into electrical energy. Connection lines 26a, 26b are provided for this purpose that can be connected in a known manner to the solar cell 32 or the solar cells 32. In order to enable the connections from the interior of the vehicle or from the motor compartment or trunk, it is advantageously provided that a channel 31 is provided in the reinforcement layer 30, which channel allows passage of at least sections of the electrical lines 26a, 26b. This makes it possible to provide the connections on the inner face the panel 10, for example, in the region of the interior of the vehicle or in the region of the motor compartment of the vehicle or the trunk of the vehicle.

(67) The arrangement of the channel 31 in the reinforcement layer 30 can be carried out after the manufacture of the reinforcement layer 30. Alternatively, corresponding inserts can also be provided in the manufacturing of the reinforcement layer.

(68) Alternatively, it can be provided that the electrical lines are already mounted after the mounting of the structure 19 on the deep-drawn film 12, and can be surrounded with foam with the introduction of the liquid polyurethane casting compound 24 and the curing to a reinforcement layer 30.

(69) Also, the channel 31 can be configured as a type of receptacle to the plug, a socket or a connecting element, for example, in the manner of a connector.

(70) As shown in the embodiment of FIG. 9b, it is provided that a channel 35 for the passage of sections of the electrical lines 26a, 26b is arranged in the film 12. The lines 26a, 26b are thus led to the exterior here.

(71) This variant is, for example, advantageous when attachments are arranged on the outer side of the panel 10 in order to store electrical energy received from the structure 19 in the attachments or to forward from the attachments or in order to provide supply electricity to electrical consumers arranged on the attachments.

(72) In the following, a family of second variants of the invention is explained based on the embodiments of FIGS. 14 to 18:

(73) These variants fall back to methods according to claim 1, having the feature groups j) and k).

(74) Reference is first made to FIG. 14, which schematically shows a container 44, in which an unfoamed granular particle foam mass 40 is arranged, and is being filled into the container 44. Individual particles are partially designated by reference numerals 41a, 41b, 41c by way of example. The unfoamed granular particles 41a, 41b, 41c can, for example, consist of a foamable plastic of EPS, EPE, or PEEK. The unfoamed granular particles 41a, 41b, 41c have a very small volume, for example, dimensions in the order of 0.1 to 3 mm outer diameter, and can have any geometry, for example, a spherical shape.

(75) FIG. 15 shows by way of example a foaming device 45, in particular in the manner of an infrared oven. Under the influence of the radiation or temperature applied by the foaming device to the particles 41a, 41b, 41c, the unfoamed granular particles 41a, 41b, 41c can grow to foamed granular particles 42a, 42b, 42c with considerable increase in volume. FIG. 15 shows the foamed granular particles 42a, 42b, 42c with an irregular contour. The invention particularly comprises foamed granular particles which have a spherical shape.

(76) The sum of the foamed granular particles 42a, 42b, 42c constitutes the granular particle foam mass 43 used as starting material for the method according to the invention.

(77) As shown in FIG. 16, in analogy to the description of the embodiment of FIG. 4, to which reference is made in order to avoid repetitions, the deep-drawn film 12 with the structure 19 mounted thereon is inserted into the lower mold 13. When the mold is open, the granular particle foam mass 43 is introduced into the cavity 33 of the mold 34 and spread there.

(78) Subsequently, the mold 34 is closed, wherein the upper mold 14 is moved toward the lower mold 13. With the mold closed, which is tempered by a heating 48, the foamed granular particles 42, 42b, 42c can be baked or sintered to each other. The baking of the granular particle foam mass 43 is carried out under the influence of temperature and/or pressure. The mold 34 can in particular be subject to thermal cycling:

(79) While a higher temperature, in particular above the melting point of the granular particle foam mass 43 is provided in order to perform the process of baking or sintering of the foamed granular particles 42a, 42b, 42c, the mold 34 is either not further heated or cooled (possibly also by a separate cooling device) after a prescribed cycle time, in order to reach a temperature below the melting point of the granular particle foam mass 43.

(80) The cured reinforcement layer 30 formed in this way is provided in this respect by a cured particle foam mass 46.

(81) In the course of baking the foamed particles 42a, 42b, 42c to each other, the particle foam mass also forms a solid connection to the deep-drawn film 12 and to the structure 19 containing the solar cells.

(82) After opening the mold 34, according to FIG. 17, the panel 10 finished in this way can be removed from the mold as shown in FIG. 18.

(83) In order to avoid repetition, reference is made to the above statements regarding the previous embodiments of FIGS. 1 to 13 that apply analogously to the embodiments of FIGS. 16 to 18.

(84) In particular, it is noted that a barrier coat layer 27 and/or a mold-paint layer 28, as is not illustrated in the drawings of the embodiment according to FIGS. 14 to 18, can also be provided in these embodiments.

(85) The invention further comprises when the foamed granular particles 42a, 42b, 42c that form the granular particle foam mass 43, are converted from a prefoamed state into a final foamed state in the course of the step of baking in the mold 34, and thus the step of baking brings with it an increase in volume of the foamed granular particles 42a, 42b, 42c from a pre-foamed state to a final foamed state.

(86) The invention comprises when foamable plastics are used to provide the granular particle foam mass, which are introduced into the mold 34 in a finally foamed state, and thus the step of baking is carried out without volume change of the granular particles 42a, 42b, 42c.

(87) Finally, the invention also comprises when a volume reduction of the foamed granular particles 42a, 42b, 42c is carried out in the course of baking as a result of the pressure effect and/or the effect of temperature in the closed mold 34.

(88) Referring to FIG. 16, it should be noted that the granular particle foam mass 43 can be introduced into the mold 34 along the insertion direction 47 manually or mechanically, wherein a distribution of the foamed granular particles 42a, 42b, 42c can be carried out independently or manually or mechanically and/or automatically over the cavity 33 of the mold.

(89) The invention further comprises an embodiment which provides that the mold 34 is overloaded, that is, an amount of granular particle foam mass is introduced into the cavity 33 of the mold 34, whose volume exceeds the volume of the cavity 33. In the case of a mold closing in the course of the step of baking the granular particles 42a, 42b, 42c, the volume of the granular particles 42a, 42b, 42c can be reduced.

(90) With regard to the embodiment of FIGS. 14 to 18, it should also be noted that the features of the embodiments of FIGS. 1 to 13, for example the mounting of the structures 19 with electrical lines containing the solar cells described on the basis of FIGS. 8 to 9b, can equally be provided.