Abstract
The present teachings relate to a photovoltaic packaging comprising a polymer back layer, photovoltaic cells electrically connected to each other, a polymer front layer which is transparent to light, and which is configured to be connected to the polymer back layer by means of welding, wherein the photovoltaic cells are located between the front and back layer, the front and back layer being connected to each other by means of a welded connection, such that the photovoltaic cells is completely enclosed between the front layer and the back layer by the welded connection, surrounding the photovoltaic cells, and wherein each individual cell is separated from the remaining of the photovoltaic cells by the welded connection. The present teachings also relate to a method of manufacturing, and to a solar panel.
Claims
1. A photovoltaic device, comprising: a transparent front layer comprising a random copolymer of polypropylene or a polycarbonate, a back layer comprising a polypropylene, wherein the back layer comprises a core comprising gas cells defined by walls of the polypropylene, and between the front layer and the back layer at least one photovoltaic cell.
2. The photovoltaic device of claim 1 wherein the core comprising gas cells defined by walls of the polypropylene is a polypropylene foam.
3. The photovoltaic device of claim 1 further comprising an encapsulant material between the front layer and the back layer.
4. The photovoltaic device of claim 1 wherein the transparent front layer comprises the random copolymer of polypropylene.
5. The photovoltaic device of claim 1 wherein the transparent front layer allows at least an average of 70% transmission of light in the wavelength range of 350 nm to 1200 nm as compared to a situation without the polymer front layer.
6. The photovoltaic device of claim 1 wherein the transparent front layer has a thickness of 20 to 1000 micrometers.
7. The photovoltaic device of claim 1 wherein the back layer has a thickness in the range of 300 to 10,000 micrometers.
8. The photovoltaic device of claim 1 wherein there are a plurality of the photovoltaic cells between the transparent front layer and the back layer.
9. The photovoltaic device of claim 8 wherein the plurality of photovoltaic cells electrically connected to each other by electrical conductors and wherein the front layer and the back layer are locally connected to each other by means of a local welded connection, such that the plurality of photovoltaic cells is completely enclosed between the front layer and the back layer by the welded connection, surrounding the plurality of photovoltaic cells, and wherein each individual cell of the plurality of photovoltaic cells is separated from the remaining of the photovoltaic cells by the welded connection.
10. A photovoltaic device, comprising: a transparent front layer comprising a random copolymer of polypropylene or a polycarbonate, a back layer comprising a polypropylene, wherein the back layer comprises reinforced polypropylene, and between the front layer and the back layer at least one photovoltaic cell.
11. The photovoltaic device of claim 10 further comprising an encapsulant material between the front layer and the back layer.
12. The photovoltaic device of claim 10 wherein the transparent front layer comprises the random copolymer of polypropylene.
13. The photovoltaic device of claim 10 wherein the back layer comprises a long glass fiber reinforced polypropylene.
14. The photovoltaic device of claim 10 wherein the transparent front layer allows at least an average of 70% transmission of light in the wavelength range of 350 nm to 1200 nm as compared to a situation without the polymer front layer.
15. The photovoltaic device of claim 10 wherein the transparent front layer has a thickness of 20 to 1000 micrometers.
16. The photovoltaic device of claim 10 wherein the back layer has a thickness in the range of 300 to 10,000 micrometers.
17. The photovoltaic device of claim 10 wherein there are a plurality of the photovoltaic cells between the transparent front layer and the back layer.
18. The photovoltaic device of claim 17 wherein the plurality of photovoltaic cells electrically connected to each other by electrical conductors and wherein the front layer and the back layer are locally connected to each other by means of a local welded connection, such that the plurality of photovoltaic cells is completely enclosed between the front layer and the back layer by the welded connection, surrounding the plurality of photovoltaic cells, and wherein each individual cell of the plurality of photovoltaic cells is separated from the remaining of the photovoltaic cells by the welded connection.
19. A method of recycling comprising providing a photovoltaic device which comprises a front layer comprising a random copolymer of polypropylene or a polycarbonate, a back layer comprising a polypropylene, and between the front layer and the back layer at least one photovoltaic cell, separating the separating the front layer comprising the random polypropylene and the back layer comprising polypropylene from the photovoltaic cell.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0044] The present teachings are described hereinafter with reference to the accompanying schematic drawings in which examples of the invention are shown and in which like reference numbers indicate the same or similar elements.
[0045] FIG. 1a shows, in plan view, a first example of a photovoltaic packaging according to the present invention,
[0046] FIG. 1b shows section Ib-Ib of the packaging of FIG. 1a, FIG. 1c shows detail Ic of the packaging of FIG. 1a,
[0047] FIG. 2a shows, in plan view, an example of a solar panel according to the invention, comprising the photovoltaic packaging according to FIG. 1a,
[0048] FIG. 2b shows section IIb-IIb of the panel of FIG. 2a,
[0049] FIG. 3a shows, in plan view, a second example of a photovoltaic packaging according to the present invention,
[0050] FIG. 3b shows section IIIb-IIIb of the packaging of FIG. 3a,
[0051] FIG. 4a shows, in plan view, a third example of a photovoltaic packaging according to the present invention,
[0052] FIG. 4b shows section IVb-IVb of the packaging of FIG. 4a,
[0053] FIG. 5a shows, in plan view, a fourth example of a photovoltaic packaging according to the present invention,
[0054] FIG. 5b shows section Vb-Vb of the packaging of FIG. 5a,
[0055] FIG. 6a shows, in plan view, a fifth example of a photovoltaic packaging according to the present invention,
[0056] FIG. 6b shows section VIb-VIb of the packaging of FIG. 6a,
[0057] FIG. 7a shows, in partial plan view, a sixth example of a photovoltaic packaging according to the present invention,
[0058] FIG. 7b shows section VIIb-VIIb of the packaging of FIG. 7a, and
[0059] FIG. 7c shows a partial side view of the packaging of FIG. 7a,
[0060] Throughout the figures, components which are equal, or at least function in a similar manner, have been indicated with the reference signs to which each time 100 is added.
DESCRIPTION OF EMBODIMENTS
[0061] FIG. 1a and 1b show a photovoltaic packaging 1 according to the present invention. The photovoltaic packaging 1 has ten photovoltaic cells, or, solar cells 3 in two parallel rows of five cells 3, while in practice the photovoltaic packaging may have less or (much) more solar cells such as a grid of six times ten solar cells. The solar cells 3 are mutually connected in an electrical manner by electrical conductors in the form of copper strips 2a, 2b, 2c. The strips 2a extend in the longitudinal direction of the packaging 1 while the strips 2b and 2c extend in the transverse direction. The main strips 2a extend between rows of solar cells 3 and are electrically connected to respective electrical contacts on the back side of each of the cells 3 by means of transverse strips 2b extending between a main strip 2a and an electrical contact of a solar cell 3. As figure la shows, the ten cells 3 are in electrical connection in a parallel configuration while the two rows share a central longitudinal strip of the strips 2a, which may be the ()-wire. The two outer strips of the strips 2a are connected by the transverse strip 2c and may be the (+)-wire. Such a parallel configuration may result in a higher durability as compared to the series configuration as shown in FIG. 4a (to be detailed below) because of the increased capability of the photovoltaic packaging 1 to deal with temperature differences between the copper strips 2a and the below described front and back sheets 6, 8. In case of lengthening of the main strips 2a due to a temperature rise, the transverse strips 2b may bend slightly in case that the solar cells 3 remain in place. This reduces the forces at, normally soldered, electrical connections between strips and solar cell contacts. Instead of strip-shaped conductors, conductors of other shapes may be used, such as wire-shaped conductors, i.e. conductive wires, such as of copper or aluminium.
[0062] The rows of cells 3 thus formed may comprise a larger number of cells, such as ten cells. The panel may comprise a plurality of such rows, such as six rows. Regarding the number of solar cells, the above holds in an analogous manner for the further examples of packagings to be described below.
[0063] The photovoltaic packaging 1 has a polymer back layer in the form of a back sheet 8 of polypropylene. The back sheet 8 has a thickness of 500 micrometer. The photovoltaic packaging also has a polymer front layer which is light transparent to such an extent that in use of the photovoltaic packaging 1 electrical power is generated by the plurality of photovoltaic cells 3 due to incident sunlight. The front layer is in the form of a front sheet 6 of polypropylene. The thickness of the front sheet 6 is 200 micrometer. The solar cells 3 are located between the front sheet 6 and back sheet 8 and do not adhere to either the front sheet 6 or the back sheet 8. Also, the front sheet 6 does not adhere to the back sheet 8, as visualized schematically in FIG. 1b.
[0064] The front sheet 6 is connected locally to the back sheet 8 by means of laser welds 4 (indicated by dashed lines), i.e connected by means of laser welding. The photovoltaic packaging 1 has longitudinal welds 4 in the direction of the rows, on each side of each row, and transverse welds between each two adjacent cells 3, thereby creating ten pockets 9, one pocket 9 for each individual cell 3. Thus, laser welds 4 surround each individual solar cell 3 so that each cell 3 is enclosed in a pocket 9 defined by the front sheet 6 and back sheet 8 and one or more of the laser welds 4. As FIG. 1a shows, a transverse connecting strip 2b from a cell 3 to a conductor strip 2a extends through a longitudinal weld 4.
[0065] The (+)-wire and ()-wires 2a can be connected to an external power cable via a junction box 12 which provides a sealed electrical external connection of the conductor strips 2a.
[0066] FIG. 1c shows in detail a junction of a longitudinal and a transverse weld 4. At the junction, a circular weld part 4a may be provided. This way, a photovoltaic packaging connecting element such as a screw 20 may safely be passed through the front 6 and back 8 sheets without compromising the full enclosure and thereby sealing from external influences such as moist and dust, of each cell 3 in its pocket 9. Using such connecting elements, the packaging may be connected to a surrounding structure such as a supporting structure.
[0067] FIGS. 2a and 2b show a solar panel 50 according to the invention. The solar panel 50 comprises the photovoltaic packaging 1 of FIGS. 1a-1c and a rigid, UV protective top layer which is transparent to light, in the form of a glass plate 51, connected to a top, sun facing side of the front sheet 6 by means of gluing the glass plate 51 to the front sheet 6, such as using an above-described Post-it adhesive. The glass plate 51 is of the same size, seen in plan view, as the front sheet 6 and back sheet 8. The solar panel 50 may additionally have a rigid further back layer in the form of a back plate connected to the back sheet, such as by means of gluing, for further strengthening of the solar panel.
[0068] FIGS. 3a and 3b show a photovoltaic packaging 101 which is to a large extent identical to the packaging 1 of FIGS. 1a-1b. Like photovoltaic packaging 1, the photovoltaic packaging 101 has a front sheet 106 and a back sheet 108, in this example both made of polyethylene and having a thickness of 300 micrometer. Conductor strips 102a, 102b, 102c are provided to mutually connect the cells of the plurality of solar cells 103 in an electrical manner, like packaging 1. Also, the front sheet 106 is connected locally to the back sheet 108 by means of laser welds 104. A laser weld 104, 104 extends continuously around each individual solar cell 103 so that each cell 103 is fully enclosed in a pocket 109 defined by the front sheet 106 and back sheet 108, as is the case with packaging 1. The difference is that each cell 103 of packaging 101 is completely surrounded by two welds, because two transverse welds 104 extend between each two adjacent cells 103 instead of one transverse weld in the packaging of FIG. 1a. for the remainder, the above description of packaging 1 applies in an analogous manner.
[0069] FIGS. 4a and 4b show a photovoltaic packaging 201 according to the present invention. The photovoltaic packaging 201 has ten photovoltaic, or, solar cells 203 in two parallel rows of five cells 203. The solar cells 203 are mutually connected in an electrical manner by electrical conductors in the form of copper strips 202a and 202d connected to respective electrical contacts on the back side of each of the cells. The strips 202a are mutually connected and may form a (+)-wire. The strips 202d are also mutually connected but are electrically isolated from the wires 202a and may form a ()-wire. Both the (+)-and ()-wire extend to a junction box 212 where they may be connected to an external power cable. As FIG. 4a shows, the five cells 203 of each of the two rows are in electrical connection in a series configuration while the two rows are connected in parallel.
[0070] The back layer 208, the front layer 206, and the pattern of welds 204, 204 is the same as in the packaging 101 of FIG. 3a-3b. Other than packaging 101, conductor strips 202a and 202d pass through transverse welds 204. At the respective intersection of a conductor strip 202a or 202d and a pair of transverse welds 204 between two adjacent cells 203, a piece of encapsulant material 260, such as of EVA, is provided at the location of the pair of transverse welds 204, between the back layer 208 and the strip 202a and 202d of a row of cells 203. A piece of encapsulant material 260 is also provided between the front layer 206 and the same strips 202a and 202d, above the first-mentioned piece 260. The two pieces of encapsulant material 260 between which the strips 202a and 202d pass increase the sealing between two adjacent pockets 209. The two stacked pieces of encapsulant material 260 are melted to the front sheet 206 and back sheet 208 and to each other, while the strips 202a and 202b pass between them. In an embodiment, a piece of encapsulant material may only be provided below, or alternatively on top of, the conductor strips. Such a piece thus connects to the front sheet 206 as well as to the back sheet 208.
[0071] The photovoltaic packaging 301 of FIGS. 5a and 5b is highly similar to packaging 201, except for the thickness of the back sheet, which may also be identical to the back sheet of packaging 201, and except for the embodiment of the encapsulant material. Instead of individual pieces 260, packaging 301 has strips 360 of encapsulant material, such as of EVA, extending in transverse direction between adjacent cells 303. As a result, between adjacent cells 303 in longitudinal direction, the packaging 301 may be cut to length at the location of a transverse encapsulant strip 360, depending on the required number of cells 303 per row. In that case, a junction box, or at least an electrical connection, may be established with the conductor strips at the location of the cut. In an embodiment, the strips 360 may extend over the entire width of the packaging. As FIG. 5b shows, packaging 301 has a strip 360 on the top side of the conductor strips 302a and 302d only, that means between the front layer 306 and the strips 302a and 302d. In this case the strip 360 is thus melted to the front sheet 306 as well as to the back sheet 308. In a further embodiment, two of such strips 360 may each time be provided between adjacent cells, similar to the two strips 260 of packaging 201.
[0072] FIGS. 6a and 6b show a photovoltaic packaging 401 which is identical to packaging 1 except for the embodiment of the back sheet thereof. Packaging 401 has a back sheet 408 having a thickness of 400 micrometer. The back sheet 408 has five mutually parallel incorporated steel wires 415, for the purpose of reinforcing the back sheet 408. The back sheet 408 is made by co-extruding the wires 415 with the polymer of the back sheet. Alternatively the wires may be laminated between two sublayers of the back-sheet 408. The wires extend in the longitudinal direction of the packaging and less or more wires may be provided. The wires 415 are electrically isolated from conductor strips 402a-402c by the back sheet material. The wires 15 provide for an increased fire protection of any objects underneath the packaging in use. In case that an object on fire falls on top of the packaging 401, the wires 415 function as a safety net; the object may melt the front and back sheet of the packaging, but cannot pass through the wires 415. Such wires 415 may also be present in the other photovoltaic packagings according to the invention as described above.
[0073] FIGS. 7a-7c show a part of a photovoltaic packaging 601 according to the invention, for the purpose of explaining an embodiment of a junction box 612 which may also be used in a similar manner in any of the packagings 1-401 according to the invention as described above. In this case the junction box 612 is formed at a transverse end 613 of the packaging 601 and it comprises two halves 612a and 612b which are glued to the transverse end 613. Encapsulant material 660 is melted between the front and back sheet 606, 608 at the end 613, to increase the sealing of the packaging 601. Conductor strips 602a and 602d extend through the encapsulant material 660 to the junction box 612.
