Lightweight photovoltaic module including a front layer made from glass or polymer and a rear layer comprising raised portions

Abstract

A lightweight photovoltaic module including: a first transparent layer forming the front face; photovoltaic cells; an assembly encapsulating the photovoltaic cells; and a second layer forming the rear face and containing an inner surface and an outer surface. The encapsulating assembly and the photovoltaic cells are located between the first and second layers. The module is characterized in that: the first layer is made from glass and/or polymer material and has a thickness that is less than or equal to 1.1 mm; the inner surface is substantially planar; and the second layer includes raised portions projecting from the outer surface, the outer surface and raised portions together defining the visible rear outer surface of the photovoltaic module.

Claims

1. A photovoltaic module, comprising: a first layer, which is transparent and forms a front face of the photovoltaic module for receiving a light flux, a plurality of photovoltaic cells arranged side by side and electrically connected together, an encapsulating assembly encapsulating the plurality of photovoltaic cells, and a second layer, which forms a rear face of the photovoltaic module and comprises an inner surface in contact with the encapsulating assembly, an outer surface opposite to the inner surface, and raised portions in a form of elongated ribs above the outer surface, wherein the encapsulating assembly and the plurality of photovoltaic cells are located between the first layer and the second layer, the first layer is made of glass and/or at least one polymer material and has a thickness of less than or equal to 1.1 mm, the inner surface of the second layer is approximately planar, the outer surface and the raised portions of the second layer together define a visible outer rear surface of the photovoltaic module, at least one first elongated rib extends from a first corner of a periphery of the outer surface of the second layer and at least one second elongated rib extends from a second corner of the periphery of the outer surface of the second layer, the first corner and the second corner being successive corners around the periphery of the outer surface of the second layer, and the at least one first elongated rib and the at least one second elongated rib extend away from the respective successive corners at an acute angle so as to intersect at least at one intersection point.

2. The module according to claim 1, wherein the first layer is made of at least one polymer material selected from the group consisting of polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyamide (PA), a fluorinated polymer, ethylene tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE), polytetrafluoroethylene (PTFE), and polychlorotrifluoroethylene (PCTFE).

3. The module according to claim 1, wherein the second layer comprises an assembly of at least one first rear layer, a second rear layer that comprises the raised portions projecting from an outer surface thereof so that the second rear layer is three-dimensional, and an adhesive layer between the first rear layer and the second rear layer to assemble the second rear layer to the first rear layer, wherein the first rear layer is placed between the encapsulating assembly and the second rear layer and has an inner surface in contact with the encapsulating assembly, the inner surface of the second layer is formed by the inner surface of the first rear layer, and the outer surface of the second layer is formed by the outer surface of the second rear layer.

4. The module according to claim 3, wherein the first rear layer is a mono or multilayer polymer film, and/or the first rear layer has a thickness between 150 and 600 m.

5. The module according to claim 3, wherein the second rear layer is made of at least one composite material.

6. The module according to claim 3, wherein the raised portions are formed by recesses made on an inner surface of the second rear layer.

7. The module according to claim 1, wherein the second layer comprises a single three-dimensional rear layer, which is in contact with the encapsulating assembly, and has an approximately planar inner surface and an outer surface having the raised portions.

8. The module according to claim 7, wherein the three-dimensional rear layer is made of at least one composite material.

9. The module according to claim 1, wherein a weight per unit area of the module is less than or equal to 7 kg/m.sup.2.

10. The module according to claim 1, wherein a thickness of the elongated ribs is between 5 and 60 mm.

11. The module according to claim 1, wherein the elongated ribs comprise principal elongated ribs and secondary elongated ribs, and the principal elongated ribs are thicker than the secondary elongated ribs.

12. The module according to claim 11, wherein the principal elongated ribs has a thickness between 20 and 60 mm, and the secondary elongated ribs has a thickness between 5 and 20 mm.

13. The module according to claim 1, wherein at least part of the elongated ribs is located on the periphery of the outer surface of the second layer so as to form at least a partial peripheral frame of the outer surface of the second layer.

14. The module according to claim 13, wherein the peripheral frame is partial so as to leave a space without any elongated ribs for integration of a junction box, which contains a wiring necessary for use of the photovoltaic module.

15. A method for manufacturing a photovoltaic module, the method comprising: assembling a photovoltaic module comprising a first layer, a plurality of photovoltaic cells encapsulated within an encapsulating assembly, and a second layer; and hot laminating at least some layers of the photovoltaic module at a temperature equal to or more than 120 C. for a lamination cycle time of at least 10 minutes, wherein the first layer forms a front face of the photovoltaic module, is transparent and made of glass and/or at least one polymer material, and has a thickness of less than or equal to 1.1 mm; the photovoltaic cells are arranged side by side and electrically connected together; the second layer forms a rear face of the photovoltaic module and comprises an approximately planar inner surface in contact with the encapsulating assembly, an outer surface opposite to the inner surface, and raised portions in a form of elongated ribs above the outer surface with the outer surface and the raised portions together defining a visible outer rear surface of the photovoltaic module; the encapsulating assembly is located between the first and second layers; at least one first elongated rib extends from a first corner of a periphery of the outer surface of the second layer and at least one second elongated rib extends from a second corner of the periphery of the outer surface of the second layer, the first corner and the second corner being successive corners around the periphery of the outer surface of the second layer; and the at least one first elongated rib and the at least one second elongated rib extend away from the respective successive corners at an acute angle so as to intersect at least at one intersection point.

16. The method according to claim 15, wherein the second layer comprises an assembly of at least one first rear layer, a second rear layer that comprises the raised portions projecting from an outer surface thereof so that the second rear layer is three-dimensional, and an adhesive layer between the first rear layer and the second rear layer to assemble the second rear layer to the first rear layer; the first rear layer is placed between the encapsulating assembly and the second rear layer and has an inner surface in contact with the encapsulating assembly; the inner surface of the second layer is formed by the inner surface of the first rear layer; the outer surface of the second layer is formed by the outer surface of the second rear layer; and the method comprises: hot laminating the first layer, the encapsulating assembly, the photovoltaic cells, and the first rear layer at a temperature greater than or equal to 120 C. for a lamination cycle time of at least 10 minutes to obtain a photovoltaic laminate; and assembling the second rear layer to said photovoltaic laminate with the adhesive layer.

17. The method according to claim 15, wherein said hot laminating comprises a single hot lamination of the first layer, the encapsulating layer, the photovoltaic cells, and the second layer at the temperature greater than or equal to 120 C. for the lamination cycle time of at least 10 minutes, and a backing mould contacts the outer surface of the second layer with geometry inverse to the raised portions on the outer surface of the second layer during the single lamination.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood after reading the following detailed description of non-limitative example embodiments of the invention, and an examination of the diagrammatic and partial figures in the appended drawing on which:

(2) FIG. 1 shows a sectional view of a classical example of a photovoltaic module containing crystalline photovoltaic cells,

(3) FIG. 2 shows an exploded view of the photovoltaic module in FIG. 1,

(4) FIG. 3 is a sectional exploded view of a first example embodiment of a photovoltaic module according to the invention,

(5) FIGS. 4A and 4B are front views partially representing the inner and outer surfaces respectively of the second rear layer of the photovoltaic module in FIG. 3,

(6) FIGS. 5A to 5D illustrate different steps in a first example of a method conforming with the invention for manufacturing a photovoltaic module similar to that shown in FIG. 3, in sectional and assembled views in FIGS. 5B and 5D, in an exploded view in FIG. 5A and a partially exploded view in FIG. 5C,

(7) FIG. 6 is a sectional exploded view of a second example embodiment of a photovoltaic module according to the invention,

(8) FIG. 7 shows a front view of the outer surface of the three-dimensional rear layer of the photovoltaic module in FIG. 6, representing support cross-pieces, and

(9) FIGS. 8A and 8B illustrate different steps in a second example of a method conforming with the invention for manufacturing a photovoltaic module similar to that shown in FIG. 6, in an exploded view in FIG. 8A and an assembled view in FIG. 8B,

(10) In all these figures, identical references may denote identical or similar elements.

(11) Furthermore, the different parts shown on the figures are not necessarily all at the same scale, to make the figures more easily understandable.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

(12) FIGS. 1 and 2 have already been described in the part dealing with the state of prior art.

(13) FIGS. 3, 4A, 4B and 5A to 5D refer to a first embodiment of the invention, while FIGS. 6, 7, 8A and 8B refer to a second embodiment of the invention.

(14) For each of these two embodiments, it is considered that the photovoltaic cells 4, interconnected by soldered tinned copper ribbons, are crystalline cells, in other words they are based on mono or multicrystalline silicon and that their thickness is between 1 and 300 m.

(15) Furthermore, the encapsulating assembly 3 is chosen to be made from two poly(ethylene vinyl acetate) (EVA) layers between which the photovoltaic cells 4 are located, each layer having a minimum thickness of 300 m, or even 200 m. As a variant, this encapsulating assembly 3 may also be a thermoplastic elastomer as described above.

(16) Moreover, although not shown on FIGS. 3 to 8B, each photovoltaic module 1 may comprise a junction box similar to the junction box 7 shown on FIGS. 1 and 2 that will contain the wiring necessary for operation of the photovoltaic module 1. This junction box can be made of plastic or rubber, and it is completely leak tight.

(17) The photovoltaic cells 4, the encapsulating assembly 3 and the junction box 7 form so-called incompressible elements in the composition of the photovoltaic module 1. Their combined weight per unit area is about 1.5 kg/m.sup.2.

(18) Advantageously, the invention includes a specific choice for materials forming the front and rear faces of the photovoltaic module 1, so as to obtain a lightweight photovoltaic module 1 with a weight per unit area of less than or equal to 7 kg/m.sup.2, and preferably less than or equal to 6 kg/m.sup.2, or even 5 kg/m.sup.2. In particular, the invention makes it possible to eliminate the thick glass layer with a thickness of about 3 mm on the front face and to eliminate the metal frame of the photovoltaic module that normally accounts for about 80% of the total weight of a photovoltaic module.

(19) Thus, in the two embodiments described below, the first layer 2 forming the front face of the photovoltaic module is a layer of glass with thickness e2 less than or equal to 1.1 mm, previously hardened using the chemical strengthening process.

(20) Obviously, these choices are in no way limitative as was described above.

First Embodiment

(21) Refer firstly to FIG. 3 that is a sectional exploded view of a first example embodiment illustrating a photovoltaic module 1 according to the invention,

(22) Note that FIG. 3 corresponds to an exploded view of the photovoltaic module 1 before the lamination steps in the first example of the method according to the invention, subsequently described with reference to FIGS. 5A to 5D. Once the lamination has been done to achieve hot vacuum pressing, the different layers are actually superposed on each other.

(23) The photovoltaic module 1 thus comprises a first transparent layer 2 made of thin glass less than or equal to 1.1 mm thick, forming the front face of the photovoltaic module 1 and that will receive a light flux, a plurality of photovoltaic cells 4 located side by side and electrically connected to each other, and an assembly 3 encapsulating the plurality of photovoltaic cells 4.

(24) According to the invention, the photovoltaic module 1 also comprises a second layer 5 forming the rear face of the photovoltaic module 1, this second layer 5 in this example being composed of an assembly of a first rear layer 5a, in contact with the encapsulating assembly 3, and a second three-dimensional rear layer 5b such that the first rear layer 5a is located between the encapsulating assembly 3 and the second rear layer 5b.

(25) The inner surface 8i in contact with the encapsulating assembly 3 of the first rear layer 5a is approximately plane so that the first rear layer 5a can bond to the encapsulating assembly 3 during the lamination operation described below.

(26) On the other hand, the outer surface 8e of the second rear layer 5b comprises raised portions 9 projecting from this outer surface 8e, the outer surface 8e and the raised portions 9 together defining the visible outer rear surface of the photovoltaic module 1. Thus, the outer surface 8e confers a three-dimensional structure or a three-dimensional reinforcement on the second rear layer 5b.

(27) Furthermore, in order to make a bond possible between the first rear layer 5a and the second rear layer 5b forming a stiffener 3D, this assembly 5 forming the second layer comprises an adhesive layer 10 between the first rear layer 5a and the second rear layer 5b. Preferably, this adhesive layer 10 can be a silicone glue.

(28) The first rear layer 5a can be made in a manner similar to the rear layer of a classical photovoltaic module 1. Preferably, the first rear layer 5a is chosen to be a mono- or multilayer polymer film, particularly of the Tedlar/polyethylene terephthalate (PET)/Tedlar type, also called TPT.

(29) The thickness e5a of this first rear layer 5a may be between 150 and 600 m, and particularly of the order of 400 m.

(30) Advantageously, the first rear layer 5a comprises an inner surface 8i, in contact with the substantially plane encapsulating assembly 3, and an outer surface in contact with the second approximately plane rear layer 5b.

(31) Furthermore, the second rear layer 5b forming a 3D stiffener, is advantageously made from a composite material, and epoxy resin/glass fibre. This guarantees mechanical strength of the photovoltaic module 1.

(32) The dimensions of the second rear layer 5b are advantageously at least equal to the dimensions of the first layer 2 of the photovoltaic module 1.

(33) FIGS. 4A and 4B are front views partially representing the inner surface 11i and outer surface 8e respectively of the second rear layer 5b of the photovoltaic module 1 in FIG. 3.

(34) As can be seen on these figures, the second rear layer 5b comprises raised portions 9 on its outer surface 8e, in the form of elongated ribs projecting from this outer surface 8e. These raised portions 9 are actually formed from complementary shaped recesses 12 made on the inner surface 11i of the second rear layer 5b. Thus, the second rear layer 5b has a vertical dimension on its outer surface 8e, due to the presence of projecting raised portions 9.

(35) Also, in this first example embodiment, the 3D stiffener formed by the second rear layer 5b has a non-plane inner surface 11i and outer surface 8e.

(36) Furthermore, as can also be seen around the periphery of the inner surface and the outer surface 8e of the second rear layer 5b, it also comprises a plurality of attachment points 13 that will be used for attachment of the photovoltaic module 1 to support cross-pieces, like those 14 shown on FIG. 7 concerning the second embodiment to form a panel of photovoltaic modules 1, and configured to authorise a separation of said support cross-pieces, for example between 735 and 1045 mm.

(37) In this example embodiment in FIGS. 4A and 4B, the elongated ribs 9 are in the form of two types of elongated ribs, namely firstly so-called principal elongated ribs 9a and secondly so-called secondary elongated ribs 9b.

(38) Advantageously, as can be seen on FIG. 4B, the thickness E1 of the principal elongated ribs 9a is greater than the thickness E2 of the secondary elongated ribs 9b.

(39) In particular, the thickness E1 of the principal longitudinal ribs 9a is between 20 and 60 mm, and preferably between 35 and 55 mm. The thickness E2 of the secondary elongated ribs 9b is between 5 and 20 mm, and preferably between 5 and 10 mm.

(40) It should be noted that according to one variant of FIGS. 4A and 4B, the elongated ribs 9 can only comprise principal elongated ribs 9a and no secondary elongated ribs 9b.

(41) Furthermore, as can be seen on FIGS. 4A and 4B, a part of the principal elongated ribs 9a is located on the periphery Pi of the outer surface 8e of the second rear layer 5b so as to form a peripheral frame for the second rear layer.

(42) However, this peripheral frame is partial because it comprises a space ES, without an elongated rib 9, provided for the integration of a junction box 7 as shown on FIG. 2, that will contain the wiring necessary for use of the photovoltaic module 1.

(43) Furthermore, in this example embodiment in FIGS. 4A and 4B, a first principal elongated rib 9a1 extends obliquely from a first corner CO1 of the periphery Pi of the outer surface 8e to the central portion of the outer surface 8e and a second principal elongated rib 9a2 extends obliquely from a second corner CO2 of the periphery Pi of the outer surface 8e to the central portion of the outer surface 8e. The first corner CO1 and the second corner CO2 are successive corners along the periphery Pi of the outer surface 8e.

(44) Advantageously, these first 9a1 and second 9a2 principal elongated ribs extend crosswise and intersect each other at a first intersection point P1 located on an axis T connecting the attachment points 13 located on the two lateral edges of the outer surface 8e.

(45) Furthermore, a third principal elongated rib 9a3 also extends obliquely from the first corner CO1 of the periphery Pi of the outer surface 8e to the central portion of the outer surface 8e and a fourth principal elongated rib 9a4 also extends obliquely from the second corner CO2 of the periphery Pi of the outer surface 8e to the central portion of the outer surface 8e.

(46) Advantageously, these second 9a2 and third 9a3 principal elongated ribs extend crosswise and intersect each other at a second intersection point P2 located approximately on, in other words close to, the axis T connecting the attachment points 13 located on the two lateral edges of the outer surface 8e.

(47) Also advantageously, these first 9a1 and fourth 9a4 principal elongated ribs extend crosswise and intersect each other at a third intersection point P3 located approximately on, in other words close to, the axis T connecting the attachment points 13 located on the two lateral edges of the outer surface 8e.

(48) FIGS. 5A to 5D illustrate different steps in the first example method conforming with the invention for manufacturing a photovoltaic module 1 similar to that shown in FIG. 3, with sectional and assembled views in FIGS. 5B and 5D, in an exploded view in FIG. 5A and a partially exploded view in FIG. 5C,

(49) FIG. 5A is an exploded view illustrating a photovoltaic structure, before lamination, comprising the first layer 2, the encapsulating assembly 3 and the photovoltaic cells 4, and the first rear layer 5a.

(50) On FIG. 5B, this same structure is represented after the photovoltaic laminate was obtained following a hot lamination step a), at a temperature greater than or equal to 120 C. and during a lamination cycle time of at least 10 minutes.

(51) FIG. 5C illustrates the assembly step of the photovoltaic laminate in FIG. 5B by bonding the second rear layer 5b on the first rear layer 5a using the adhesive layer 10.

(52) Finally, FIG. 5D illustrates the photovoltaic module 1 obtained conforming with the invention.

(53) The photovoltaic module 1 has a weight per unit area of less than 7 kg/m.sup.2. The deflection observed at the centre after a test at a pressure of 5400 Pa is less than 40 mm and does not exceed 25 mm.

Second Embodiment

(54) Refer now to FIG. 6 that is a sectional exploded view of a second example embodiment illustrating a photovoltaic module 1 according to the invention.

(55) Note also that FIG. 6 corresponds to an exploded view of the photovoltaic module 1 before the lamination steps in the second example of the method according to the invention, described below with reference to FIGS. 8A and 8B. Once the lamination has been done to achieve hot vacuum pressing, the different layers are actually superposed on each other.

(56) The photovoltaic module 1 thus comprises a first transparent layer 2 made of thin glass less than or equal to 1.1 mm thick, forming the front face of the photovoltaic module 1 and that will receive a light flux, a plurality of photovoltaic cells 4 located side by side and electrically connected to each other, and an assembly 3 encapsulating the plurality of photovoltaic cells 4.

(57) In accordance with the invention, the photovoltaic module 1 also comprises a second layer 5 forming the rear face of the photovoltaic module 1, this second layer 5 in this example being composed of a single three-dimensional rear layer 5 in contact with the encapsulating assembly 3.

(58) The inner surface 8i of this three-dimensional rear layer 5 is substantially plane so that it can bond to the encapsulating assembly 3 during the lamination operation, while the outer surface of the three-dimensional rear layer 5 comprises raised portions 9 forming a projection relative to this outer surface 8e.

(59) FIG. 7 shows a front view of the outer surface 8e of the three-dimensional rear layer 5 of the photovoltaic module 1 in FIG. 6, also representing support cross-pieces 14 for attachment of the photovoltaic module 1 to a photovoltaic panel.

(60) Advantageously, this three-dimensional rear layer 5 forms a 3D structure made of a composite material, particularly of the polyamide/glass fibre type. It guarantees mechanical strength of the photovoltaic module 1.

(61) The outer surface 8e of this three-dimensional rear layer 5 and the raised portions 9 together define the visible rear outer surface of the photovoltaic module 1.

(62) Unlike the second rear layer 5b in the first embodiment, represented on FIGS. 4A and 4B, the three-dimensional layer 5 of the second embodiment represented on FIG. 7, has an approximately plane inner surface and an outer surface 8e provided with raised portions 9. This is the reason why this layer can bond to the encapsulating assembly 3 directly during a lamination operation while the second rear layer 5b in the first embodiment cannot due to its inner surface that is not plane, which justifies the second bonding step with an adhesive layer 10.

(63) Furthermore, as can be seen on FIG. 7, the three-dimensional rear layer 5 comprises raised portions 9 in the form of elongated ribs projecting from the outer surface 8e. Thus, the three-dimensional rear layer has a vertical dimension on its outer surface 8e, originating from the presence or raised portions 9, while this vertical dimension is non-existent on its substantially plane inner surface. As mentioned above, the thickness of the elongated ribs 9 may be as described above, and may possibly comprise so-called principal elongated ribs and so-called secondary elongated ribs, as described above.

(64) Note that the general pattern formed by the raised portions 9 on the outer surface 8e of the three-dimensional rear layer 5 that can be seen on FIG. 7 could also be used as a general pattern formed by raised portions 9 on the outer surface 8e of the second rear layer, visible on FIG. 4B, and vice versa.

(65) FIGS. 8A and 8B illustrate different steps in the second example method conforming with the invention for manufacturing a photovoltaic module 1 similar to that shown in FIG. 6, in an exploded view in FIG. 8A and an assembled view in FIG. 8B.

(66) FIG. 8A is an exploded view illustrating a photovoltaic structure, before lamination, comprising the first layer 2, the encapsulating assembly 3 and the photovoltaic cells 4, and the three-dimensional rear layer 5.

(67) On FIG. 8B, this same structure is represented after the single hot lamination step at a temperature greater than or equal to 120 C. for a lamination cycle duration equal to at least 10 minutes on this structure to obtain the photovoltaic module 1 according to the second embodiment-.

(68) During this single lamination step, a backing mould is preferably used in contact with the outer surface 8e of the second layer 5 due to the fact that its outer surface 8e is not plane, since it contains raised portions 9. The geometry of this backing mould is the inverse of the geometry with raised portions 9 on the outer surface 8e of the three-dimensional rear layer 5. It thus matches the geometry of the stack of layers in the laminator. This backing mould is preferably a good thermal conductor, thus being made from a metallic material, for example aluminium and/or steel.

(69) Furthermore, for both of the embodiments envisaged above, the weight per unit area of each of the second rear layer 5b and the three-dimensional rear layer 5 is preferably be less than or equal to 2 kg/m.sup.2, particularly less than or equal to 1.8 kg/m.sup.2, and more particularly less than or equal to 1.5 kg/m.sup.2. The weight per unit area of the second rear layer 5b can be less than or equal to the weight per unit area of the three-dimensional rear layer 5.

(70) Advantageously, due to the use of a front face made of glass with a thickness less than or equal to 1.1 mm or polymer, the weight per unit area of the photovoltaic module 1 may be less than or equal to 7 kg/m.sup.2, preferably less than or equal to 6 kg/m.sup.2 or even 5 kg/m.sup.2, namely not more than half the weight per unit area of a classical photovoltaic module.

(71) This significant weight saving makes it possible to install the photovoltaic module 1 according to the invention on applications for which a standard module weighing about 12 kg/m.sup.2 could not be used.

(72) Furthermore, due to the use of composite materials to make the second layer 5, and more precisely the second rear layer 5b and the three-dimensional rear layer 5, the photovoltaic module 1 according to the invention maintains its mechanical properties to resist stresses in standards IEC 61215 and IEC 61730.

(73) The module obtained is also compatible with an industrial line for fabrication of standard photovoltaic modules.

(74) Obviously, the invention is not limited to the example embodiments that have just been described. An expert in the subject can make various modifications to it.