PHOTOVOLTAIC MODULE COMPRISING A POLYMER FRONT FACE

Abstract

A photovoltaic module including a transparent first layer forming a front face, plural photovoltaic cells, and an assembly encapsulating the photovoltaic cells. The first layer includes plural plates independent from each other, each plate located opposite a photovoltaic cell. Rigidity of the encapsulating assembly is defined by a Young's modulus of encapsulation material greater than or equal to 75 MPa at ambient temperature and a thickness of the encapsulating assembly between 0.4 and 1 mm. The first layer includes at least one transparent polymer material of acrylic block copolymers or a composition including at least one acrylic block copolymer having formula (A).sub.nB, in which: n is an integer greater than or equal to 1; A is an acrylic or methacrylic homo- or copolymer having a glass transition temperature greater than 50° C.; and B is an acrylic or methacrylic homo- or copolymer having a glass transition temperature less than 20° C.

Claims

1-23. (canceled)

24. A photovoltaic module comprising: a transparent first layer forming a front face of the photovoltaic module configured to receive a luminous flux; a set of a plurality of photovoltaic cells arranged side-by-side and connected together electrically; an assembly encapsulating the plurality of photovoltaic cells; a second layer forming a rear face of the photovoltaic module, the encapsulating assembly and the set of a plurality of photovoltaic cells being located between the first and second layers; wherein the first layer comprises a plurality of plates independent from each other, each plate being located opposite at least one photovoltaic cell, to form a discontinuous front face of the photovoltaic module; wherein rigidity of the encapsulating assembly is defined by a Young's modulus of the encapsulation material greater than or equal to 75 MPa at ambient temperature and a thickness of the encapsulating assembly of between 0.4 and 1 mm; and wherein the first layer includes at least one transparent polymer material belonging to acrylic block copolymers or of a composition comprising at least one acrylic block copolymer having following formula:
(A).sub.nB wherein: n is an integer greater than or equal to 1; A is an acrylic or methacrylic homo- or copolymer having a glass transition temperature greater than 50° C., or polystyrene, or an acrylic-styrene or methacrylic-styrene copolymer; and B is an acrylic or methacrylic homo- or copolymer having a glass transition temperature less than 20° C., comprised of methyl acrylate, ethyl acrylate, ethylhexyl acrylate, butyl methylacrylate or butyl acrylate.

25. A module according to claim 24, wherein the block A is chosen from polymethyl methacrylate, phenyl polymethylacrylate, benzyl polymethylacrylate or isobornyl polymethylacrylate, or a copolymer with a base of two or more of methyl methacrylate monomers, phenyl methacrylate, benzyl methacrylate, or isobornyl methacrylate.

26. A module according to claim 25, wherein the block A is of the polymethyl methacrylate modified with acrylic or methacrylic comonomers.

27. A module according to claim 24, wherein the block A and/or the block B comprise styrene, acrylic, or methacrylic comonomers.

28. A module as claimed in claim 24, wherein the block B incorporates comonomers, and wherein the block A incorporates methacrylic acid.

29. A module as claimed in claim 24, wherein the encapsulating assembly includes two core layers of encapsulation material located in an immediate vicinity of the set of photovoltaic cells, respectively on either side of the set of photovoltaic cells.

30. A module as claimed in claim 24, wherein the encapsulation material of the layers forming the encapsulating assembly has a Young's modulus at ambient temperature greater than or equal to 100 MPa.

31. A module as claimed in claim 24, wherein the encapsulating assembly is supplemented with one or more other additional layers of encapsulation material, rigidity of the additional layer or layers of encapsulation material decreasing when moving away from the encapsulating assembly.

32. A module according to claim 29, further comprising at least one additional layer of encapsulation material, located between the first layer and the core layer of encapsulation material in the immediate vicinity.

33. A module according to claim 32, wherein the at least one additional layer of encapsulation material has a Young's modulus at ambient temperature less than 75 MPa.

34. A module according of claim 31, wherein the additional layer or layers of encapsulation material are comprised of a material chosen from thermoplastic polyolefins.

35. A module according to claim 34, wherein the additional layer or layers of encapsulation material are comprised of functional thermoplastic polyolefins with a polyamide graft base, grafted onto a functional polyolefin backbone with ethylene units.

36. A module as claimed in claim 24, wherein the second layer forming the rear face of the photovoltaic module is comprised of at least one polymer material and/or of at least one composite material.

37. A module as claimed in claim 24, wherein rigidity of the second layer forming the rear face of the photovoltaic module is defined by a factor of rigidity, corresponding to the Young's modulus at ambient temperature of the material of the second layer multiplied by the thickness of the second layer, between 5 and 15 GPa.Math.mm.

38. A module as claimed in claim 24, wherein spacing between two neighbouring photovoltaic cells is greater than or equal to 1 mm.

39. A module as claimed in claim 24, further comprising a shock-absorbing intermediate layer located between the first layer forming the front face of the photovoltaic module and the assembly encapsulating the plurality of photovoltaic cells, allowing for assembly of the first layer on the encapsulating assembly.

40. A module according to claim 34, wherein the intermediate layer is comprised of at least one polymer material.

41. A module according to claim 39, wherein rigidity of the intermediate layer is defined by a Young's modulus at ambient temperature of the material of the intermediate layer less than or equal to 50 MPa and a thickness of the intermediate layer between 0.01 and 1 mm.

42. A photovoltaic structure assembly, comprising: a rigid support; a photovoltaic module as claimed in claim 24; and a fixing layer located between the rigid support and the photovoltaic module, allowing for adherence of the photovoltaic module to the rigid support.

43. Use, for application thereof on a rigid support of a photovoltaic module comprising: one transparent first layer forming a front face of the photovoltaic module configured to receive a luminous flux; a set of a plurality of photovoltaic cells arranged side-by-side and connected together electrically; an assembly encapsulating the plurality of photovoltaic cells; a second layer forming a rear face of the photovoltaic module, the encapsulating assembly and the set of a plurality of photovoltaic cells being located between the first and second layers; the first layer comprising a plurality of plates independent from each other, each plate being located opposite at least one photovoltaic cell, to form a discontinuous front face of the photovoltaic module; rigidity of the encapsulating assembly being defined by a Young's modulus of the encapsulation material greater than or equal to 75 MPa at ambient temperature and a thickness of the encapsulating assembly of between 0.4 and 1 mm; the first layer being comprised of at least one transparent polymer material belonging to the acrylic block copolymers or of a composition comprising at least one acrylic block copolymer having following formula:
(A).sub.nB wherein: n is an integer greater than or equal to 1; A is an acrylic or methacrylic homo- or copolymer having a glass transition temperature greater than 50° C., or polystyrene, or an acrylic-styrene or methacrylic-styrene copolymer; and B is an acrylic or methacrylic homo- or copolymer having a glass transition temperature less than 20° C., and the photovoltaic module being applied on the rigid support by an intermediary of a fixing layer.

44. A method for carrying out a photovoltaic module according to claim 24, comprising: a) hot laminating at a temperature greater than 150° C. the set of layers that comprise the photovoltaic module other than the first layer forming the front face of the photovoltaic module and any shock-absorbing intermediate layer, located between the first layer and the encapsulating assembly the plurality of photovoltaic cells; b) laminating at a temperature less than or equal to 150° C., the first layer forming the front face of the photovoltaic module, and any intermediate layer, on the layers that comprise the photovoltaic module laminated together during a), c) gluing, with beforehand depositing of a liquid glue whether or not reactive, or pressing, the first layer forming the front face of the photovoltaic module, and any intermediate layer, on the that comprise the photovoltaic module laminated together during a).

45. A method for carrying out a photovoltaic module according to claim 44, further comprising: d) hot laminating at a temperature greater than or equal to 150° C. all of the layers that comprise the photovoltaic module.

46. A method for carrying out a photovoltaic structure assembly according to claim 44, and successively further comprising: d) fixing the photovoltaic module onto a rigid support to form the photovoltaic structure assembly, by a fixing layer of the photovoltaic structure assembly.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0119] The invention can be understood better when reading the following detailed description of a non-limiting embodiment of the latter, as well as by examining the single FIGURE, diagrammatical and partial, of the annexed drawing, which shows, as a cross-section and as an exploded view, an embodiment of a photovoltaic structure assembly comprising a photovoltaic module in accordance with the invention.

[0120] In this single FIGURE, the various portions shown are not shown necessarily to a uniform scale, in order to make the FIGURE more legible.

DETAILED DESCRIPTION OF A PARTICULAR EMBODIMENT

[0121] Note that FIG. 1 corresponds to an exploded view of the photovoltaic structure assembly 10 before the steps of laminating of the method according to the invention. Once these steps have been carried out, the various layers are in reality superimposed on one another, but also slightly deformed in such a way that at least the plates 8 of the first layer 3 sink into the assembly formed by the intermediate layer 9 and the encapsulating assembly 6a, 6b which are deformed. The steps of laminating provide a hot pressing and in a vacuum. According to the thicknesses of the various layers, the plates 8 can be flush or not with the photovoltaic module 1, the material of the intermediate layer 9 and perhaps that of the encapsulating assembly 6a, 6b also able to fill in at least one portion of the spaces between the plates 8.

[0122] As explained hereinabove, the photovoltaic module 1 in accordance with the invention is designed to be sufficiently flexible in order to be able to apply it, in particular by gluing, onto a possible rigid support 2, able to have a surface roughness, in other words not necessarily flat and smooth. In addition, the photovoltaic module 1 in accordance with the invention is also provided to resist static or dynamic pressures that can range up to 1500 kN/m.sup.2, even 5000 kN/m.sup.2. The rigid support 2 is advantageously sufficiently rigid to not become deformed when the same stress as that applied to the photovoltaic module 1 is applied. It can for example be formed by a roof covering, be made of concrete or sheet metal, among others.

[0123] As can as such be seen in FIG. 1, the photovoltaic module 1 comprises a transparent first layer 3 forming the front face of the module 1 intended to receive a luminous flux, an encapsulating assembly 6a, 6b, obtained by the melting of two upper 6a and lower 6b core layers of encapsulation material, with this encapsulating assembly being overmounted by an additional layer of encapsulation material 11, located above the upper core layer of encapsulation material 6a, a set 4 of photovoltaic cells 5 taken between the two upper 6a and lower 6b core layers of encapsulation material, and a second layer 7 forming the rear face of the photovoltaic module 1 intended to be glued to the rigid support 2.

[0124] The two core layers of encapsulation material 6a and 6b forming the encapsulating assembly, as well as the possible intermediate layer 9 described hereinbelow, form a relatively supple structure that can be carried out from a single material or from several materials in the event of chemical incompatibility.

[0125] In accordance with the invention, the first layer 3 is comprised of a transparent polymer material of the nanostructured polymethyl methacrylate (PMMA) shock type. It can in particular be nanostructured PMMA shock marketed by the ARKEMA company under the brand ShieldUp®.

[0126] In addition, the first layer 3 comprises a plurality of plates 8 independent from each other, with each plate 8 being located opposite a photovoltaic cell 5, in such a way as to form a discontinuous front face of the photovoltaic module 1. The thickness of the first layer 3 can be greater than 0.1 mm, and ideally between 0.5 and 6 mm. In this example, the first layer 3 is as such comprised of several plates 8, of dimensions equal to 162×162 mm, of nanostructured PMMA shock with a thickness equal to 3 mm.

[0127] Moreover, advantageously, the rigidity of the additional layer of encapsulation material 11 is chosen to be lower than the respective rigidities of the two core layers of encapsulation material 6a, 6b. In particular, the two core layers of encapsulation material 6a, 6b can have a Young's modulus E at ambient temperature greater than 75 MPa, advantageously greater than 100 MPa, and more preferably greater than 200 MPa, and the additional layer of encapsulation material 11 can have a Young's modulus E at ambient temperature less than 75 MPa, and more preferably less than or equal to 50 MPa.

[0128] In other words, advantageously, the photovoltaic module 1 is comprised of an assembly of layers of encapsulation material 11, 6a, 6b forming a stack of layers wherein a graduation or rigidity gradient is established from the core layers of encapsulation material 6a, 6b in contact with the set 4 of photovoltaic cells 5 to the additional layer of encapsulation material 11.

[0129] Although in this example a single additional layer of encapsulation material 11 has been considered, several additional layers of encapsulation material 11 can alternatively be stacked via overlapping on the upper core layer of encapsulation material 6a and/or on the lower core layer of encapsulation material 6b. This stacking it then carried out in such a way that for each new layer n+1 stacked, its Young's modulus E at ambient temperature is less than the Young's modulus E at ambient temperature of the preceding layer n.

[0130] The additional layer of encapsulation material 11 can be comprised of a material chosen from thermoplastic polyolefins, and in particular thermoplastic polyolefins from the Apolhya® Solar Film range from the Arkema company, for example such as the Apolhya® Solar Film encapsulant of grade R333A or EXP A having a Young's modulus E between 50 and 100 MPa at ambient temperature and an intermediate rigidity between that of the ionomer of the core layers of encapsulation material 6a, 6b and that of the TPU of the intermediate layer 9.

[0131] Moreover, the photovoltaic cells 5 are interconnected electrically with one another with a spacing s between two neighbouring cells 5 between 1 and 30 mm. The photovoltaic cells 5 can be so-called “crystalline” photovoltaic cells, i.e. which have a silicon crystal or silicon polycrystalline base, with a homojunction or heterojunction, and a thickness less than or equal to 250 μm. In addition, in this example, each plate 8 extends by overlapping on either side of the underlying photovoltaic cell 5 over a distance of about 3 mm, in such a way that the spacing between two adjacent plates 8 is here equal to the spacings enter two neighbouring cells 5 less about 2 times 3 mm, i.e. about 6 mm.

[0132] Furthermore, the rigidity of each core layer of encapsulation material 6a and 6b is defined by a Young's modulus E at ambient temperature of the encapsulation material greater than or equal to 50 MPa, preferably greater than or equal to 200 MPa, and a thickness e of the layer 6a, 6b between 0.2 and 1 mm.

[0133] The core layers of encapsulation material 6a and 6b form an encapsulating assembly preferentially chosen to be an ionomer such as the ionomer marketed under the name of ionomer Jurasol® of the DG3 type by the Jura-plast company or the ionomer marketed under the name of PV5414 by the Du Pont company, having a Young's modulus greater than or equal to 200 MPa at ambient temperature and a thickness of about 500 μm.

[0134] The second layer 7 forming the rear face of the photovoltaic module 1 is comprised of a polymer material such as thermosetting resins such as resins with an epoxy base, whether or not transparent, or a composite material, for example of the polymer/glass fibre type.

[0135] In addition, as can be seen in FIG. 1, the photovoltaic module 1 also comprises a so-called “shock-absorbing” intermediate layer 9 located between the first layer 3 and the additional layer of encapsulation material 11.

[0136] The intermediate layer 9 is optional and substantially has its utility if there is a chemical incompatibility between the first layer 3 and the additional layer of encapsulation material 11.

[0137] The intermediate layer 9 allows for the gluing of the first layer 3 onto the additional layer of encapsulation material 11.

[0138] The intermediate layer 9 is for example comprised of a standard encapsulant used in the field of photovoltaics, such as ethylene vinyl acetate (EVA) copolymer, a polyolefin, silicone, thermoplastic polyurethane, polyvinyl butyral, among others. It can further be constituted by a liquid resin of the acrylic, silicone or polyurethane type, single-component or bicomponent, heat cross-linkable, photochemically or cold (i.e. at ambient temperature). It can also be comprised of an adhesive that is sensitive to pressure of the PSA (“Pressure-Sensitive Adhesive”) type.

[0139] In this example, the intermediate layer 9 is comprised of a thermoplastic film, namely thermoplastic polyurethane also known under the acronym TPU, such as TPU of the TPU Dureflex® A4700 type, marketed by the Bayer company or PX1001 marketed by the American company Polyfilm, with a thickness equal to environ 380 μm.

[0140] The intermediate layer 9 makes it possible to fulfil two main functions. On the one hand, it allows for the adhesion of the first layer 3 on the additional layer of encapsulation material 11 for the case where the two layers are not compatible chemically. On the other hand, it makes it possible to create within the photovoltaic module 1 a “shock-absorbing” layer of a certain flexibility that makes it possible to improve the resistance to shocks and to the mechanical loads of the module 1.

[0141] Moreover, the photovoltaic structure assembly 10 in accordance with the invention shown in FIG. 1 also comprises a rigid support 2. The rigid support 2 can be of any type of material. It can be flat or curved, smooth or rough.

[0142] In order to allow for the gluing of the photovoltaic module 1 onto the rigid support 2, the assembly 10 also comprises a fixing layer 12. This fixing layer 12 is comprised of a glue for adhering the module 1 to the rigid support 2.

[0143] A method for carrying out a photovoltaic module 1 and a photovoltaic structure assembly 10 in accordance with the invention shall now be described.

[0144] The method comprises a first step of hot laminating a) at a temperature of about 170° C. and in a vacuum (pressure less than or equal to 10 mbar) of the layers comprising 11, 6a, 4, 6b and 7 of the photovoltaic module 1 other than the first layer 3 and the intermediate layer 9. This first step a) of laminating is carried out for about 15 minutes so as to obtain a “laminate” of encapsulated photovoltaic cells 5. The parameters for the laminating, such as the temperature, time and pressure, can however depend on the encapsulating material used.

[0145] Then, the method comprises a second step of hot laminating b) at a temperature of about 125° C. and in a vacuum of the “laminate” obtained during the first step a) with the first layer 3 forming the front face of the photovoltaic module 1 using the intermediate layer 9. This second step b) is carried out during a period of about 30 minutes so as to obtain the photovoltaic module 1 according to the invention. Before implementing this second step b), the plates 8 of the first layer 3 can advantageously be treated using a Corona treatment equipment so as to obtain a surface energy that is greater than or equal to 48 dyn/cm.

[0146] These first a) and second b) steps of laminating are then followed by a step of fixing the photovoltaic module 1 onto the rigid support 2 which makes it possible to form the photovoltaic structure assembly 10.

[0147] Consequently, the photovoltaic module 1 in accordance with the invention can have a mechanical resistance that is increased suitable for constraining applications in terms of mechanical stresses, but also have a flexibility by pieces due to the presence of a discontinuous front face 3, allowing it to have different forms in order to adapt to different types of surfaces, for example uneven or with imperfect flatness. In addition, the presence of a reinforced rear face 7 can make it possible to improve the resistance to the punching of this rear face 7 of the module 1, with this punching able to result from the roughness of the support 2 whereon the module 1 is applied and which can lead to cracks of the photovoltaic cells 5 of the photovoltaic module 1.

[0148] Of course, the invention is not limited to the embodiment which has just been described. Various modifications can be made to it by those skilled in the art.

[0149] The expression “comprising a” must be understood as being synonymous with “comprising at least one”, unless mentioned otherwise.