PHOTOVOLTAIC MODULES FOR RIGID CARRIERS

Abstract

A photovoltaic module including at least a transparent first layer forming a front face of the photovoltaic module to receive a light flux, an assembly of plural photovoltaic cells arranged side by side and connected together electrically, an assembly encapsulating the photovoltaic cells, and a second layer fo ming a rear face of the photovoltaic module. The encapsulating assembly and assembly of photovoltaic cells is located between the first and second layers. The first layer includes at least a transparent polymer material and plural plates independent from one another, each plate located opposite at least one photovoltaic cell, to form a discontinuous front face for the photovoltaic module. 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 is between 0.4 and 1 mm.

Claims

1-15. (canceled)

16. A photovoltaic module comprising: a transparent first layer forming a front face of the photovoltaic module configured to receive the light flux; an assembly of plural photovoltaic cells arranged side by side and connected together electrically; an encapsulated assembly of the plural photovoltaic cells; a second layer forming a rear face of the photovoltaic module, the encapsulating assembly and the assembly of plural photovoltaic cells being located between the first and second layers; wherein the first layer includes at least a transparent polymer material and plural plates independent from one another, each plate being located opposite at least one photovoltaic cell, to form a discontinuous front face for the photovoltaic module, and 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 is between 0.4 and 1 mm.

17. A module in accordance with claim 16, wherein the encapsulation material of the layers forming the encapsulating assembly exhibit a Young's modulus at ambient temperature greater than or equal to 100 MPa.

18. A module according to claim 16, wherein the second layer forming the rear face of the photovoltaic module includes at least one polymer material.

19. A module according to claim 16, wherein the second layer foiining the rear face of the photovoltaic module includes at least one composite material.

20. A module according to claim 16, wherein rigidity of the second layer foil ling the rear face of the photovoltaic module is defined by a rigidity factor, corresponding to Young's modulus at ambient temperature of the material of the second layer multiplied by thickness of the second layer, of between 5 and 15 GPa.mm.

21. A module according to claim 16, wherein spacing between two adjacent photovoltaic cells is greater than or equal to 1 mm.

22. A module according to claim 16, further comprising an intermediate layer located between the first layer forming the front face of the photovoltaic module and the encapsulating assembly of plural photovoltaic cells, enabling assembly of the first layer to the encapsulating assembly.

23. A module according to claim 22, wherein the intermediate layer includes at least one polymer material.

24. A module according to claim 22, wherein rigidity of the intermediate layer is defined by the Young's modulus of the material of the intermediate layer less than or equal to 50 MPa at ambient temperature and a thickness of the intermediate layer of between 0.01 and 1 mm.

25. A module according to claim 16, wherein the thickness of the first layer forming the front face of the photovoltaic module is greater than or equal to 0.1 mm.

26. A photovoltaic structure assembly, comprising: a rigid backing; a photovoltaic module according to claim 16; and an attachment layer located between the rigid backing and the photovoltaic module, enabling adhesion of the photovoltaic module to the rigid backing.

27. Use, for its application to a rigid backing, of a photovoltaic module comprising: a transparent first layer forming a front face of the photovoltaic module configured to receive light flux; an assembly of plural photovoltaic cells arranged side by side and connected together electrically; an assembly encapsulating the plural photovoltaic cells; a second layer forming a rear face of the photovoltaic module, the encapsulating assembly and the assembly of plural photovoltaic cells being located between the first and second layers; the first layer including at least one transparent polymer material including plural plates independent from one another, each plate being located opposite at least one photovoltaic cell, to form a discontinuous front face for the photovoltaic module; and 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 is between 0.4 and 1 mm, the photovoltaic module being applied to the rigid backing via an attachment layer.

28. A process for production of a photovoltaic module according to claim 16, comprising: a) hot rolling at a temperature greater than 150 C. of constituent layers of the photovoltaic module apart from the first layer forming the front face of the photovoltaic module and a possible intermediate layer located between the first layer and the encapsulating assembly of plural photovoltaic cells; b) rolling at a temperature strictly less than or equal to 150 C., of the first layer forming the front face of the photovoltaic module, and any intermediate layer, to the constituent layers of the photovoltaic module rolled together during a).

29. A process for production of a photovoltaic module according to claim 16, comprising: a) hot rolling at a temperature greater than or equal to 150 C. of all constituent layers of the photovoltaic module.

30. A process for production of a photovoltaic structure assembly according to claim 26, comprising: a) hot rolling at a temperature greater than 150 C. of constituent layers of the photovoltaic module apart from the first layer forming the front face of the photovoltaic module and a possible intermediate layer located between the first layer and the encapsulating assembly of plural photovoltaic cells, b) rolling at a temperature strictly less than or equal to 150 C., of the first layer forming the front face of the photovoltaic module, and any intermediate layer, to the constituent layers of the photovoltaic module rolled together during a), and d) attachment of the photovoltaic module to a rigid backing to form the photovoltaic structure assembly, via the attachment layer of the photovoltaic structure assembly.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0086] The invention may be better understood by the detailed description below, of a non exclusive example of its use, together with examination of the single diagrammatic and partial figure, of the drawing in the appendix, illustrating, in section and exploded view, an example of the use of a photovoltaic structure assembly incorporating a photovoltaic module in accordance with the invention.

[0087] In this single FIGURE, the different parts represented are not necessarily drawn at the same scale, in order to improve the legibility of the figure.

DETAILED DESCRIPTION OF A PARTICULAR PRODUCTION METHOD

[0088] Reference is made below to FIG. 1, which illustrates in section and exploded view an example of a photovoltaic structure assembly 10 incorporating a photovoltaic module 1 in accordance with the invention.

[0089] It should be noted that FIG. 1 corresponds to an exploded view of the photovoltaic structure assembly 10 prior to the rolling stages of the process according to the invention. Once the rolling stages have been performed, the different layers are in fact superimposed on one another, but also slightly deformed such that at least the plates 8 of the first layer 3 are embedded in the assembly formed by the intermediate layer 9 and the encapsulating assembly 6a, 6b which are deformed. The rolling stages ensure hot compression in vacuum. According to the thickness of the various layers, the plates 8 may or may not be flush with the photovoltaic module 1, the material of the intermediate layer 9 and possibly that of the encapsulating assembly 6a, 6b which may at least partly fill the spaces between the plates 8.

[0090] As already explained, the photovoltaic module 1 in accordance with the invention is designed to be sufficiently flexible to enable its attachment, in particular by bonding, to a rigid backing 2, which may exhibit surface roughness, in other words not necessarily flat and smooth. Additionally, the photovoltaic module 1 in accordance with the invention is also intended to withstand static or dynamic pressures of up to 1500 kN/m.sup.2, or even 5000 kN/m.sup.2. The rigid backing 2 should preferably by sufficiently rigid not to deform when subjected to the same stress as that applied to photovoltaic module 1. It may for example by formed by a roof covering, made of concrete or sheet metal, among others.

[0091] As can be seen in FIG. 1, the photovoltaic module 1 incorporates a transparent first layer 3 forming the front face of module 1 intended to receive the light flux, an encapsulating assembly 6a, 6b, obtained by fusion of two layers of encapsulation material, top 6a and bottom 6b, an assembly 4 of photovoltaic cells 5 sandwiched between the top 6a and bottom 6b layers of encapsulation material, and a second layer 7 forming the rear face of the photovoltaic module 1 intended for bonding to a rigid backing 2.

[0092] The two layers of encapsulation material 6a and 6b forming the encapsulating assembly, as well as the possible intermediate layer 9 described subsequently, form a relatively supple structure which may consist of a single or several materials in the event of chemical incompatibility.

[0093] According to the invention, the first layer 3 consists of a transparent polymer and incorporates an assembly of plates 8 which are independent from one another, each plate 8 being located opposite a photovoltaic cell 5, such as to form the discontinuous front face of the photovoltaic module 1.

[0094] The transparent polymer material of the first layer 3 may for example be chosen between polycarbonate (PC), polymethyl methacrylate (PMMA), ethylene tetra fluoro ethylene (ETFE), or polyvinylidene fluoride (PVDF), among others. Additionally, the thickness of the first layer 3 may be greater than 0.1 mm, and ideally between 0.5 and 6 mm. In this example, the first layer 3 thus consists of several plates 8, of dimensions 162 162 mm, of 3 mm thick PMMA.

[0095] Additionally, the photovoltaic cells 5 are connected together electrically spaced apart by distance s between adjacent cells 5, of between 1 and 30 mm. The photovoltaic cells 5 may be so-called crystalline cells, i.e. based on crystals or polycrystals of silicon, with a homojunction or heterojunction, and of thickness less than or equal to 250 m. Additionally, in this example, each plate 8 overlaps the subjacent photovoltaic cell 5 on each side by a distance of about 3 mm, such that the spacing between two plates 8 is in this case equal to the spacing s between 2 adjacent cells 5 less about 2 times 3 mm, i.e. about 6 mm.

[0096] Moreover, the rigidity of each 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, or 75 MPa, or even 100 MPa, preferably greater than or equal to 200 MPa, and a thickness e of layers 6a, 6b of between 0.2 and 1 mm.

[0097] The layers of encapsulation material 6a and 6b form an encapsulating assembly preferably chosen to be an ionomer such as the ionomer marketed under the name of jurasol ionomer type DG3 by the Jura-plast company or the ionomer marketed under the name of PV5414 by Du Pont, featuring a Young's modulus at ambient temperature greater than or equal to 200 MPa and a thickness of about 500 m.

[0098] The second layer 7 forming the rear face of the photovoltaic module 1 on the other hand consists of a polymer material such as thermosetting resins such as epoxy based resins, transparent or not, or a composite material, for example of the polymer/fibreglass type. In this example, the second layer 7 consists of a composite material of polymer/fibreglass type, in particular a polypropylene and fibreglass based fabric with a fibreglass content of 60% by weight, such as Thermopreg fabric P-WRt-1490-PP60W marketed by the Owens Corning Vetrotex company, around 1 mm thick and whose Young's modulus at ambient temperature is around 12 GPa.

[0099] Additionally, although it is not shown, a possible adhesive, or compatibilising layer (its presence being justified in the event of chemical incompatibility), may be located between the second layer 7 forming the rear face of the photovoltaic module 1 and the encapsulating assembly formed by the two layers of encapsulation material 6a and 6b on either side of the assembly 4 of photovoltaic cells 5. This compatibilising layer may enable bonding of the second layer 7 to the bottom layer of encapsulation material 6b. In the event of use of Thermopreg fabric P-WRt-1490-PP60W for the second layer 7, the compatibilising layer may preferably be chosen to be a film of type Mondi TK41001 of approximately 50 m thickness.

[0100] Also, as can be seen in FIG. 1, the photovoltaic module 1 also incorporates an intermediate so-called damping layer 9 located between the first layer 3 and the encapsulating assembly formed by the two layers of encapsulation material 6a and 6b on either side of the assembly 4 of photovoltaic cells 5.

[0101] The intermediate layer 9 is optional and is essentially useful in the event of chemical incompatibility between the first layer 3 and the top encapsulation material 6a.

[0102] The intermediate layer 9 enables bonding of the first layer 3 to the top encapsulation material 6a.

[0103] The intermediate layer 9 for example consists of a standard encapsulant used in the photovoltaic domain, such as the ethylene-vinyl-acetate (EVA) copolymer, a polyolefine, silicone, polyurethane thermoplastic, polyvinyl butyral, among others. It may also consist of a liquid resin acrylic type, silicone or polyurethane, single or two-part, cross-linked at high temperature, photochemically or at low temperature (i.e. ambient temperature). It may also consist of a pressure-sensitive adhesive of type PSA (Pressure-Sensitive Adhesive).

[0104] In this example, the intermediate layer 9 consists of a thermoplastic film, in particular thermoplastic polyurethane also known as TPU, such as type TPU Dureflex A4700 marketed by Bayer or PX1001 marketed by the American Polyfilm company, of thickness equal to about 380 m.

[0105] The intermediate layer 9 fulfils two main functions. Firstly, it ensures the adhesion of the first layer 3 to the top encapsulation material 6a in the event that the two layers are not chemically compatible. Secondly, it enables the establishment of a damping layer for the photovoltaic module 1 providing a certain flexibility which enhances the resistance of the module 1 to impact and to mechanical loads.

[0106] Additionally, the photovoltaic structure assembly 10 in accordance with the invention shown in FIG. 1 also incorporates a rigid backing 2. The rigid backing 2 may be of any type of material. It may be flat or curved, smooth or rough.

[0107] In order to enable bonding of the photovoltaic module 1 to the rigid backing 2, assembly 10 also includes an attachment layer 12. This attachment layer 12 consists of an adhesive to bond module 1 to the rigid backing 2.

[0108] A production process is described below to produce photovoltaic module 1 and a photovoltaic structure assembly 10 in accordance with the invention.

[0109] The process includes a first stage a) of hot rolling at a temperature of about 170 C. and in vacuum (pressure less than or equal to 10 mbar) of the constituent layers 6a, 4, 6b and 7 of the photovoltaic module 1 apart from the first layer 3 and the intermediate layer 9. This first hot rolling stage a) is conducted for about 15 minutes in order to obtain a laminate of encapsulated photovoltaic cells 5. The rolling parameters, such as the temperature, the time and the pressure, are however dependent on the encapsulating material used.

[0110] Next, the process includes a second stage b) of hot rolling at a temperature of about 125 C. and in vacuum of the laminate obtained during the first stage a) with the first layer 3 forming the front face of the photovoltaic module 1 together with the intermediate layer 9. This second stage b) is conducted for about 30 minutes such as to obtain the photovoltaic module 1 according to the invention. Prior to execution of this second stage b), the plates 8 of the first layer 3 may advantageously be treated with Corona treatment equipment in order to achieve a surface energy level greater than or equal to 48 dyn/cm.

[0111] These first a) and second b) rolling stages are then followed by an attachment stage for the photovoltaic module 1 to the rigid backing 2 which thus forms the photovoltaic structure assembly.

[0112] In consequence, the photovoltaic module 1 in accordance with the invention may exhibit enhanced mechanical strength, suitable for constraining applications in terms of mechanical loading, such as the type of solar road, whilst at the same time providing flexibility in parts due to the presence of a discontinuous front face 3, which enables it to adopt different shapes to adapt to different types of surfaces, for example uneven or imperfectly flat. Additionally, the presence of a reinforced rear face 7 may improve the resistance to piercing of this rear face 7 of module 1, such piercing could be the result of the roughness of the support 2 on which module 1 is applied and which could cause cracking of the photovoltaic cells 5 of the photovoltaic module 1.

[0113] Naturally, the invention is not limited to the example of use described above. Various modifications may be introduced by experienced operators.

[0114] The expression including one should be taken as synonymous with including at least one, except if specified otherwise.