Photovoltaic element

Abstract

According to the present invention there is provided a photovoltaic element, comprising a photovoltaic laminate; a structural substrate; wherein the photovoltaic element further comprises a plurality of hairs which are arranged to improve adhesion between said photovoltaic laminate and said structural substrate. There is also provided an intermediate product which is used in the manufacture of such a photovoltaic element and a method of manufacturing such a photovoltaic element.

Claims

1. A method of manufacturing a photovoltaic element, comprising the steps of providing a flexible photovoltaic laminate; forming a semi-finished product comprising said flexible photovoltaic laminate with a plurality of hairs extending from a surface of said flexible photovoltaic laminate by gluing the plurality of hairs to the surface of said flexible photovoltaic laminate, wherein the plurality of hairs define an uncovered first surface; and subsequently fixing a structural substrate on the semi-finished product by moulding the structural substrate directly on the uncovered first surface of said plurality of hairs glued to the surface of the photovoltaic laminate such that the plurality of hairs are embedded into the structural substrate, said plurality of hairs providing improved adhesion between said flexible photovoltaic laminate and the structural substrate.

2. The method of claim 1, wherein the flexible photovoltaic laminate is applied against a profiled, corrugated, or otherwise non-planar surface of a first mould element.

3. The method of claim 2, wherein the photovoltaic laminate is vacuum-sucked into the first mould element against the corrugated surface, causing said flexible photovoltaic laminate to contour to a corrugated profile of the corrugated surface.

4. A photovoltaic element comprising a semi-finished product, wherein the semi-finished product comprises: a flexible photovoltaic laminate, comprising a photovoltaic module, an adhesive layer with a first side attached to said photovoltaic module, and a flexible substrate attached at a first side of the flexible substrate to a second side of said adhesive layer, wherein said second side of said adhesive layer is opposite said first side of said adhesive layer; and a layer which comprises a plurality of hairs glued to a second side of the flexible substrate, wherein said second side of said flexible substrate is opposite said first side of said flexible substrate; and a rigid structural substrate fixed onto the semi-finished product; wherein said plurality of hairs extend from said second surface of the flexible substrate and are embedded into said rigid structural substrate to improve adhesion between said semi-finished product and said rigid structural substrate.

5. A photovoltaic element according to claim 4, wherein the photovoltaic element has a corrugated or other non-planar profile.

6. A photovoltaic element according to claim 4, wherein the rigid structural substrate is a composite comprising resin and fibres.

7. A photovoltaic element according to claim 4, wherein said layer is made of felt or felt-like material.

8. A photovoltaic element according to claim 4, wherein the rigid structural substrate is over-moulded, over-injected, or over-infused onto said layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood with the aid of the description of an embodiment given by way of example only and illustrated by the figures, in which:

(2) FIG. 1 provides a cross-section view of a photovoltaic element according to an embodiment of the present invention; and

(3) FIG. 2 provides a cross-section view of a photovoltaic element according to a further embodiment of the present invention;

(4) FIG. 3 provides a cross-section view of a photovoltaic element according to a further embodiment of the present invention; and

(5) FIG. 4 provides a cross-section view of a photovoltaic element according to a further embodiment of the present invention;

(6) FIGS. 5a-b illustrate the steps involved in the manufacture of the photovoltaic element shown in FIG. 1.

(7) FIG. 6 provides a photovoltaic element according to a further embodiment of the present invention.

DETAILED DESCRIPTION OF POSSIBLE EMBODIMENTS OF THE INVENTION

(8) FIG. 1 provides a cross-section view of a photovoltaic element, in the form of a roof element 1, according to an embodiment of the present invention. The roof element 1 can be used to construct a roof or wall structure on for example a house, caravan, boat or on any other structure for that matter. Typically, a plurality of these roof elements 1 are co-operatively arranged to construct the roof or wall structure. The roof element 1 element is non-planar and has a corrugated profile defined by corrugations 2. The corrugations 2 in this particular example provide additional structural rigidity to the roof element 1.

(9) The roof element 1 comprises an active layer in the form of a photovoltaic laminate 3, 5 secured to a structural substrate layer 7. The photovoltaic laminate is a semi-finished product and comprises in this example a laminate with a flexible photovoltaic module 3 and a first flexible substrate 5 (back sheet); and a structural substrate 7. The photovoltaic module layer 3 is secured to the flexible back sheet 5 by means of a first adhesive layer 9a, or by any other suitable means.

(10) The lower face of the flexible photovoltaic laminate 3, 5 is secured to the structural substrate layer 7 by applying the structural substrate 7 in molten form to a surface 13 of the flexible photovoltaic laminate 3, 5 and subsequently allowing the structural substrate 7 to harden on the surface 13 of the photovoltaic laminate 3, 5. Thus, the structural substrate 7 is directly over-moulded onto the back sheet 5.

(11) The structural substrate 7 and possibly the flexible back sheet 5 comprise fibres 4 (or resin) which provide structural support to said substrates 5,7. It should be understood that the substrates are not limited to having fibres 4 (or resin) and one or both of the substrates 5, 7 may comprise fibres 4 (or resin). The fibres 4 (or resin) will increases the strength of the substrates 5, 7 making them more resistant to breakage. The fibres 4 in the back sheet 5 of the photovoltaic laminate are shown to be arranged so they extend substantially parallel to the surface 13 of the back sheet. The fibres 4 in the structural substrate 7 are shown to be arranged so be arranged substantially parallel to the surface 15 of the structural substrate 7. However, it should be understood that the fibres may take any other suitable arrangement, for example the fibres may have a random orientation or they may be arranged as a mesh.

(12) The flexible photovoltaic module 3 has a thickness within the range 0.2 to 2 mm. The thin structure of the flexible photovoltaic module 3 ensures that the flexible photovoltaic module 3 is very flexible. The flexible photovoltaic module 3 is however brittle and easy to tear.

(13) The flexible back sheet 5 of the photovoltaic laminate provides structural support to the flexible photovoltaic module 3 so that the flexible photovoltaic module 3 cannot be easily torn. While being more rigid than the flexible photovoltaic module 3, the back sheet 5 is still flexible, thus when the flexible photovoltaic module 3 is secured to the back sheet 5 to form a stack, this stack remains flexible. The back sheet 5 in this particular example comprises Polyethylene or polypropylene; however it will be understood that the back sheet 5 could comprise any other suitable material, especially plastic material, or a laminate of different materials.

(14) The structural substrate 7 provides structural support for the roof element 1 by supporting the photovoltaic laminate in the roof element 1. Being more rigid and robust than the flexible photovoltaic module 3 and the back sheet 5 which form the roof element 1, the structural substrate 7 makes that photovoltaic element 1 suitable for building a roof or wall for example. The structural substrate 7 in this particular example is made up of a composite of fibres, such as glass fibres, in a resin; however it will be understood that the structural substrate 7 could comprise any other suitable material. The structural substrate 7 is over-moulded onto the surface 13 of the back sheet 5 to secure the structural substrate 7 directly to the back sheet 5.

(15) As shown in FIG. 1, the lower layer 5 of the photovoltaic laminate 3, 5 comprises a plurality of hairs 11 which are integral to the photovoltaic laminate 3, 5. The plurality of hairs may be made integral to the photovoltaic laminate 3, 5 using any suitable method; for example the hairs may be made integral to the photovoltaic laminate 3, 5 during the manufacture of the back sheet 5; for example the hairs 11 may be incorporated into the back sheet 5 of the photovoltaic laminate during manufacture when the back sheet 5 is in a molten state; or the hairs 11 may be glued to the back sheet 5. The photovoltaic laminate 3, 5 with the hair secured on it may be distributed as a semi-finished product.

(16) At least some of the plurality of hairs 11 are arranged at an interface 12 between the photovoltaic laminate 3, 5 and the structural substrate 7. The hairs 11 are arranged to extend substantially perpendicularly from the surface 13 of the photovoltaic laminate 3, 5, into the structural substrate 7. The plurality of hairs 11 increase the surface contact area at the surface 13 of the photovoltaic laminate 3, 5 which is available for adhesion. The hairs 11 also extend into the structural substrate 7 to anchor the photovoltaic laminate 5 to the structural substrate 7. Thus, improved adhesion between the flexible photovoltaic laminate 3, 5 and structural substrate 7 is achieved. Ultimately, better adhesion between the flexible photovoltaic laminate 3, 5 and structural substrate 7 means that the photovoltaic laminate 3, 5 is less likely to become separated from the structural substrate 7, and consequently the photovoltaic laminate and the structural substrate 7 remain secured to one another even after having been subjected to the effects of weathering for long periods.

(17) FIG. 2 provides a cross-section view of a photovoltaic element in the form of a roof element 10, according to a second embodiment of the present invention. The roof element 10 has many of the same features as the roof element 1 shown in FIG. 1 and like features are awarded the same reference numerals.

(18) The roof element 10 comprises a photovoltaic laminate with a back sheet 25. As was the case in the first embodiment, the photovoltaic laminate comprises a back sheet 25 that provides structural support to a flexible photovoltaic module 3 so that the flexible photovoltaic module 3 cannot be easily torn. While being more rigid than the flexible photovoltaic module 3, the back sheet 25 of the photovoltaic laminate is still flexible, thus when the photovoltaic module layer 3 secured to the back sheet 25 to form a stack, this stack of remains flexible. The back sheet 25 in this particular example comprises Polyethylene or polypropylene; however it will be understood that the back sheet 25 could comprise any suitable material, or laminate of different materials. Unlike the back sheet 5 of the roof element 1 shown in FIG. 1, the back sheet 25 in the embodiment shown in FIG. 2 does not comprise hairs integral to the back sheet 25.

(19) The roof element 10 further comprises a layer 27 which is secured to a surface 23 of the photovoltaic laminate 3, 25. The layer 27 may comprise felt or felt-like material, such as felt, fibrous materials, fleece, non-woven materials, non-woven fabrics, etc. We will simply refer to this layer as a felt layer or felt-like layer without distinction. The felt layer 27 may be secured to the surface 23 using any suitable means (e.g. adhesive). The structural substrate 7 is over-moulded onto the felt layer 27 to directly secure the structural substrate 7 to the felt layer 27.

(20) The felt layer 27 comprises a plurality of hairs 111. The hairs act in the same manner as described for the embodiment shown in FIG. 1; namely the plurality of hairs 111 increase the surface contact area at the surface 13 of the photovoltaic laminate which is available for adhesion, and the plurality of hairs 111 will also extend into the structural substrate 7 to anchor the photovoltaic laminate to the structural substrate 7. Thus, improved adhesion between the photovoltaic laminate and structural substrate 7 is achieved. Ultimately, improved adhesion between the photovoltaic laminate 3, 25 and structural substrate 7 means that the flexible photovoltaic laminate 3, 25 is less likely to become separated from the structural substrate 7; accordingly, the flexible photovoltaic laminate 3, and the structural substrate 7 remain secured to one another even after having been subjected to the effects of weathering for a prolonged period.

(21) As described above the hairs are provided on the photovoltaic laminate. It will be understood that, in all embodiments, the hairs could alternatively or additionally be provided on the structural layer. In this case the photovoltaic laminate could be over-moulded or calandered onto the structural substrate.

(22) FIG. 3 provides a cross-section view of a photovoltaic element in the form of a roof element 100, according to a further embodiment of the present invention. The embodiment shown in FIG. 3 has many of the same features as the embodiment shown in FIG. 1, and like features are awarded the same reference numerals.

(23) Unlike the embodiment shown in FIG. 1 the structural substrate 7 is not directly secured to the flexible photovoltaic laminate 5, rather the structural substrate 7 is secured to the flexible photovoltaic laminate 5 by means of a second adhesive layer 9b.

(24) The hairs 11 act in a similar advantageous manner to improve the adhesion between the flexible photovoltaic laminate 5 and the structural substrate 7; namely, the plurality of hairs 11 increase the surface contact area at the surface 13 of the flexible photovoltaic laminate 5 which is available for adhesion. At least some of the plurality of hairs 11 extend substantially perpendicularly from a surface 13 of the flexible photovoltaic laminate 5, and into the second adhesive layer 9b. The hairs 11 anchor the flexible photovoltaic laminate 5 to the second adhesive layer 9b. Thus, improved adhesion between the flexible photovoltaic laminate 5 and second adhesive layer 9b is achieved. Ultimately, better adhesion between the flexible photovoltaic laminate 5 and second adhesive layer 9b means that the flexible photovoltaic laminate 5 is less likely to become separated from the structural substrate 7, and consequently the flexible photovoltaic laminate 5 and structural substrate 7, remain secured to one another even after having been subjected to the effects of weathering for long periods.

(25) Referring to FIGS. 1-3 it should be understood that additionally, the structural substrate 7 may also comprise a plurality of hairs. The hairs may extend perpendicularly from a surface 15 of the structural substrate 7 into the optional second adhesive layer 9b or directly into the flexible photovoltaic laminate 3, 5. The plurality of hairs will increase the surface contact area at the surface 15 of the structural substrate 7 which is available for adhesion and the hairs will also extend into the adhesive layer 9b or into the flexible photovoltaic laminate 3, 5 to anchor the structural substrate 7 to the second adhesive layer 9b or to the flexible photovoltaic laminate 5. Thus, improved adhesion between the structural substrate 7 and flexible photovoltaic laminate 3, 5 can be achieved. This will further strengthen the adhesion between the photovoltaic laminate 3, 5 and the structural substrate 7 so that they less likely to become separated.

(26) FIG. 4 provides a cross-section view of a photovoltaic element in the form of a roof element 1000, according to a further embodiment of the present invention. The embodiment shown in FIG. 4 has many of the same features as the embodiment shown in FIG. 2, and like features are awarded the same reference numerals.

(27) Unlike the embodiment shown in FIG. 2 the structural substrate 7 is not directly secured to the felt layer 27, rather the structural substrate 7 is secured to the felt layer 27 by means of a second adhesive layer 9b.

(28) The hairs 111 in the felt layer 27 act in a similar advantageous manner to improve the adhesion between the flexible photovoltaic laminate 3, 5 and the structural substrate 7; namely, the plurality of hairs 111 increase the surface contact area at the surface 23 of the flexible photovoltaic laminate 3, 5 which is available for adhesion, and the plurality of hairs 111 will also extend into the adhesive layer 9b to anchor the flexible photovoltaic laminate 3, 25 to the second adhesive layer 9b. Thus, improved adhesion between the flexible photovoltaic laminate 3, 25 and second adhesive layer 9b can be achieved. Ultimately, improved adhesion between the flexible photovoltaic laminate 3, 25 and second adhesive layer 9b means that the flexible photovoltaic laminate 3, 25 is less likely to become separated from the structural substrate 7. Accordingly, the flexible photovoltaic laminate 3, 25 and structural substrate 7 remain secured to one another even after having been subjected to the effects of weathering for a prolonged period.

(29) It should be understood that additionally the structural substrate 7 may also comprise a felt layer 27 which has a plurality of hairs which extend perpendicularly from a surface 15 of the structural substrate 7 into the second adhesive layer 9b or directly into the flexible photovoltaic laminate 3, 5. The plurality of hairs will increase the surface contact area at the surface 15 of the structural substrate 7 which is available for adhesion and the hairs will also extend into the adhesive layer 9b or into the flexible photovoltaic laminate 3, 5 to anchor the structural substrate 7 to the second adhesive layer 9b or to the flexible photovoltaic laminate 3, 5. Thus improved adhesion between the structural substrate 7 and flexible photovoltaic laminate 3, 5 can be achieved.

(30) FIGS. 5a-b illustrate the steps involved in the manufacture of the roof element 1 shown in FIG. 1. The method first involves preparation of a photovoltaic laminate comprising in this example a flexible photovoltaic module 3 and a back sheet 5; using known methods.

(31) A plurality of hairs 11 are made integral to the back sheet 5 of the photovoltaic laminate such that that they extend from a surface 13 of the back sheet 5; this can be done using any suitable method; for example the hairs 11 may be incorporated into the surface 13 of the flexible photovoltaic laminate 3, 5 during the manufacture of the flexible photovoltaic laminate 3, 5, for example during manufacture of the lowest layer of the photovoltaic laminate; for example the hairs 11 may be incorporated into the surface 13 of the back sheet 5 when the back sheet 5 is in a molten state during manufacture; or the hairs 11 may be simply glued to the surface 13 of the flexible photovoltaic laminate 3,5.

(32) When manufacturing the roof element 10 as shown in FIG. 2, instead of providing a plurality of hairs integral to the flexible photovoltaic laminate, a felt layer 27 comprising a plurality of hairs, is simply secured to the surface 13 of the flexible photovoltaic laminate 5.

(33) Next the flexible photovoltaic module 3 is secured to the back sheet 5 by means of an adhesive 9a to form a stack 12, i.e., the photovoltaic laminate. Due to the flexible nature of the flexible photovoltaic module 3 and back sheet 5, the stack or photovoltaic laminate 12 will be flexible. The flexible photovoltaic laminate 12 is then applied against a corrugated surface 35 of a first mould element 30a. The photovoltaic laminate 12 may be pressed or vacuum-sucked into the first mould element 30a against the corrugated surface 35, causing the photovoltaic laminate 12 to contour to the corrugated profile of the corrugated surface 35.

(34) A vacuum is applied though channels 33 defined in the first corrugated die element 30a; the vacuum sucks on the photovoltaic laminate 12 so that the photovoltaic laminate 12 does not become removed from the surface 35 of the first mould element 30a.

(35) The structural substrate 7 is prepared in a molten state using known methods. Optionally, resins and/or fibres 4 (as shown in FIG. 5b) may be incorporated into the structural substrate 7 when preparing it; when incorporated into the structural substrate 7, the resins or fibres 4 will provide structural support to the structural substrate 7.

(36) The photovoltaic laminate 12 is then moved towards a surface 37 of a second mould element 30b. The second mould element 30b also comprises a corrugated surface 37, as shown in FIG. 5a. The photovoltaic laminate 12 is positioned such that the corrugations on the stack 12 correspond to the corrugations in corrugated surface 37 of the second mould element 30b (i.e. peaks in the corrugations in the photovoltaic laminate 12 overlay troughs in the corrugations in on corrugated surface 37 of the second mould element 30b).

(37) As shown in FIG. 5b, the photovoltaic laminate 12 is held in a position above the corrugated surface 37 of the second mould element 30b, so that a channel 39 is defined by the corrugated surface 37 of the second mould element 30b and the surface 13 of the back sheet 5.

(38) The structural substrate 7 in its molten state is then injected into the channel 39, using injecting means 41, until the channel 39 is full of molten structural substrate 7. In this way the structural substrate 7 is over-moulded onto the surface 13 of the back sheet 5. The corrugated surface 37 of the second mould element 30b, and the corrugated profile of the photovoltaic laminate 12, will force the injected molten structural substrate 7 attain a corrugated profile.

(39) The plurality of hairs 11 increase the surface contact area at the surface 13 of the back sheet 5 which is available for adhesion with the molten structural substrate 7. Furthermore, as the molten structural substrate 7 moves into the channel 39, at least some of the plurality of hairs 11 which extend from the surface 13 of the back sheet 5, will become embedded in the molten structural substrate 7.

(40) The molten structural substrate 7 is then allowed to harden. Once the molten structural substrate 7 has hardened the embedded hairs 11 will anchor the flexible photovoltaic laminate 3, 5 to the hardened structural substrate 7. Accordingly, improved adhesion between the flexible photovoltaic laminate 3, 5 and the structural substrate 7 is achieved. Ultimately, improved adhesion between the back sheet 5 and the structural substrate 7 means that the flexible photovoltaic laminate 3, 5 is less likely to become separated from the structural substrate 7, and the layers remain secured to one another even after having been subjected to the effects of weathering for a prolonged period.

(41) Similar steps are used to prepare the embodiments shown in FIGS. 3 and 4. In this case the structural substrate 7 is prepared independently and allowed to harden. The photovoltaic laminate 12 is then positioned above the hardened structural substrate 7 to define a channel between the photovoltaic laminate and structural substrate 7. Adhesive is then injected into the channel, using injecting means, until the channel is full of adhesive. As was the case in the method describe above, the plurality of hairs increase the surface contact area at the surface 13 of the flexible photovoltaic laminate 3, 5 which is available for adhesion. Furthermore, as the adhesive moves into the channel, the plurality of hairs will become embedded in the adhesive to anchor the flexible photovoltaic laminate 3, 5 in the injected adhesive. Accordingly, improved adhesion between the flexible photovoltaic laminate 3, 5 and the injected adhesive is achieved; improved adhesion between the flexible photovoltaic laminate 3, 5 and the injected adhesive means that the flexible photovoltaic laminate 3,5 is less likely to become separated from the structural substrate 7, and the flexible photovoltaic laminate 3, 5 and structural substrate 7 remain secured to one another even after having been subjected to the effects of weathering for a prolonged period.

(42) FIG. 6 shows a photovoltaic element 600 according to a further embodiment of the present invention. The photovoltaic element 600 has many of the same features as the photovoltaic element 1 shown in FIG. 1. And like features are awarded the same reference numerals.

(43) The photovoltaic element 600 further comprises a plurality of crystalline silicon wafers 601 which are located within the active layer 3. Each successive wafer is electrical connected by means of electrical connectors 603. The wafers might have some limited flexibility.

(44) Various modifications and variations to the described embodiments of the invention will be apparent to those skilled in the art without departing from the scope of the invention as defined in the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiment.