Method for disassembling the back layer of a photovoltaic module

Abstract

The invention relates to a method for disassembling a photovoltaic module, said photovoltaic module comprising: A rear layer (1) forming a first protective element on the rear face of the photovoltaic module (M), this rear layer being made from at least one polymer material, An intermediate layer, interposed between the rear layer (1) and a front layer (3), and comprising an encapsulation envelope (21) in which photovoltaic cells (20) are placed, The front layer (3) forming a second protective element on the front face of the photovoltaic module (M), The method comprising a step of winding the rear layer around a tool (4) to detach it from the intermediate layer, The tool (4) being heated locally during the implementation of the winding step. Figure to be published with the abstract: Figure 4

Description

Title of the invention: Method for disassembling the rear layer of a photovoltaic module Technical field of the invention

[0001] The present invention relates to a method for disassembling the rear layer of a photovoltaic module. The invention also relates to the system enabling the implementation of this method. State of the art

[0002] A photovoltaic module comprises photovoltaic cells intended to convert solar energy into electrical energy.

[0003] Such a photovoltaic module contains many interesting materials to recover and recycle when the module is at the end of its life or faulty.

[0004] Conventionally, a photovoltaic module is in the form of a panel composed of the assembly of three superimposed layers fixed together: - A rear layer (called "backsheet") forming a first protective element on the rear face; - A second layer, called the intermediate layer; this intermediate layer comprises the photovoltaic cells, the electrical connection between the cells and an encapsulation envelope arranged around the photovoltaic cells; this encapsulation envelope can be formed of two protective films, between which the photovoltaic cells are placed; - A front layer forming a second protective element on the front face; this front layer can be made of glass so that it can be crossed by the captured light rays;

[0005] With a view to recycling a photovoltaic module, various methods have already been considered. A first method consists of crushing the module in its entirety, then subjecting it to various thermal and / or chemical treatments in order to separate the materials which go into its composition, such as glass, silver, copper, silicon, etc. This first method is however energy-intensive and not very environmentally friendly.

[0006] Patent application WO2019 / 043329A1 proposes another method for disassembling a photovoltaic module, which consists of removing each layer of the module to separate it, by cutting it with an abrasive wire. Each removed layer can then be processed separately in order to recover the materials of interest. This latter method has certain drawbacks. It requires several separate processing stations, first for cutting, then for grinding each layer withdrawn.

[0007] Patent application FR3017551A1 proposes a method for removing the rear layer and the first adjoining encapsulation film, in order to expose the photovoltaic cells, the latter remaining retained on the other encapsulation film. This removal is carried out by heating the photovoltaic module from below, by detaching a corner of the assembly formed by the rear layer and the encapsulation film and by rolling up said assembly to detach it. The heating is carried out using an infrared lamp. To detach the assembly, thermal assistance is applied, by blowing hot air at a temperature between 300°C and 400°C.

[0008] This solution does not allow only the rear layer of the photovoltaic module to be detached. In addition, heating the intermediate layer to high temperatures (over 300°C) is likely to result in the release of fluorinated compounds.

[0009] The aim of the invention is to propose a solution making it possible to detach only the rear layer of a photovoltaic module, the solution allowing simple and clean detachment of this layer, without tearing it, by limiting the release of fluorinated compounds and then allowing recovery of said layer and disassembly of the other layers of the module.

[0010] The invention notably allows clean detachment of the rear layer, i.e. no residue of the rear layer remains on the intermediate encapsulation layer, after removal, allowing improved recycling of the different layers and materials of the photovoltaic module. Statement of the invention

[0011] This aim is achieved by a method of disassembling a photovoltaic module, said photovoltaic module comprising: - A rear layer forming a first protective element on the rear face of the photovoltaic module, this rear layer being made from at least one polymer material, - An intermediate layer, interposed between the back layer and a front layer, and comprising an encapsulation envelope in which photovoltaic cells are placed, - The front layer forming a second protective element on the front face of the photovoltaic module, - The method comprising a step of winding the back layer around a tool to detach it from the intermediate layer, - The tool being heated locally during the implementation of the winding step.

[0012] According to a particular feature, the method comprises a step of adjusting the temperature of the tool, said temperature being chosen to at least partially melt said intermediate layer.

[0013] According to another feature, the method comprises a prior step of detaching a corner or an edge of the rear layer, by preheating.

[0014] According to another feature, the preheating is implemented by localized heating of the photovoltaic module.

[0015] According to another feature, the method comprises a subsequent step of removing the intermediate layer by sanding using an abrasive belt.

[0016] The invention also relates to a system for disassembling a photovoltaic module, used to implement the method as defined above, said photovoltaic module comprising: - A rear layer forming a first protective element on the rear face of the photovoltaic module, this rear layer being made from at least one polymer material, - An intermediate layer, inserted between the back layer and a front layer and comprising an encapsulation envelope in which photovoltaic cells are placed, - The front layer forming a second protective element on the front face of the photovoltaic module, - The system comprising: - A tool capable of peeling off the back layer from the intermediate layer, said back layer being intended to wrap around the tool when it is peeled off, - Heating means integrated into the tool.

[0017] According to a particular feature, said tool has an elongated shape along a longitudinal axis and comprises a slot extending along its longitudinal axis, forming a receiving housing for a corner or an edge of said rear layer.

[0018] According to another feature, the heating means integrated into the tool are of the induction type.

[0019] According to another feature, the system comprises means for adjusting the temperature of the tool, said temperature being chosen to at least partially melt said intermediate layer of the photovoltaic module.

[0020] According to another feature, the system comprises a support on which the photovoltaic module rests, via its front face.

[0021] According to another feature, the system comprises a preheating device arranged to heat at least one area of ​​the support or arranged to directly heat the rear layer of the photovoltaic module.

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[0032] According to another feature, the preheating device comprises one or more infrared lamps or induction heating means. Brief description of the figures Other features and advantages will appear in the detailed description which follows, given with reference to the attached drawings in which: - [Fig.l] represents, seen in perspective, a multi-layer architecture of a photovoltaic module; - [Fig.2] represents, seen in section, the multi-layer architecture of a photovoltaic module; - [Fig.3] shows an exemplary embodiment of the tool used in the disassembly system of the invention; - [Fig.4] schematically illustrates the principle of disassembly of the rear layer of the photovoltaic module, implemented using the disassembly system of the invention; - [Fig.5] shows the different stages of the method of the invention; - [Fig.6] shows an example of carrying out a disassembly step of the intermediate layer of the photovoltaic module; Detailed description of at least one embodiment Photovoltaic module [Fig.l] [Fig.2] [Fig.4] In the remainder of the description, the front face of the photovoltaic module M corresponds to a face of the module receiving the light rays and the rear face corresponds to the face opposite the front face. In the remainder of the description, each layer of the photovoltaic module has two opposite faces, a first face facing backwards and a second face facing forwards. The photovoltaic module has two opposite main faces, a first face 10 facing backwards and a second face 30 facing forwards. Hereinafter, "protective element" means an element which can have a stiffening function and / or a surface protection function. With reference to [Fig.l] and [Fig.2], in a known manner, a photovoltaic module comprises several layers superimposed and assembled together: - A rear layer 1 (commonly called "backsheet") forming a first protective element on the rear face of the photovoltaic module; this rear layer is usually made of a polymer-type material; - An intermediate layer 2, interposed between the rear layer and the front layer (described below), allowing the assembly of one side of the rear layer and the other side of the front layer; this intermediate layer comprises the photovoltaic cells 20, the electrical connectors 22 and an encapsulation envelope 21 arranged around the photovoltaic cells; - A front layer 3 forming a second protective element on the front face of the photovoltaic module; this front layer 3 is usually made of glass and corresponds to that exposed to light rays;

[0033] It should be noted that in the attached figures, the photovoltaic module M is shown turned upside down, so that its rear face 10 is located above and its front face 30 is located below.

[0034] For the sake of readability in the attached figures, the different layers of the module are not shown to scale. For example, the rear layer 1 may have a thickness of a few hundred μm (for example approximately 350 μm), the intermediate layer 2 may have a thickness of up to 1 mm and the front layer 3 may have a thickness of approximately 3 to 4 mm.

[0035] The back layer 1 can in particular provide a gas and water impermeability function, an electrical protection / insulation function and a mechanical protection function. This back layer 1 can be made from a fluorinated polymer. It can be polyvinyl fluoride (PVF), for example marketed under the name TEDLAR (registered trademark) by the company DuPont (registered trademark).

[0036] In a non-limiting manner, the rear layer 1 may itself be composed of a stack of several layers: a PVF layer, a PET (poly(ethylene terephthalate)) layer, a PVF layer.

[0037] In the intermediate layer 2, the encapsulation envelope 21 is conventionally made of a polymer such as EVA (Ethylene-Vinyl Acetate) forming a material to which the back layer 1 on one side and the front layer 3 on the other side can adhere and allow the three layers to be assembled together. The three layers can be assembled together by hot rolling, so that the back layer and the front layer adhere to the material of the encapsulation envelope, thus forming a single-piece stack. It should be noted that the material forming this intermediate encapsulation layer can also be a thermoplastic polyolefin (TPO), an elastomeric polyolefin (EPO) or an ionomer.

[0038] In the intermediate layer 2, the photovoltaic cells 20 are generally connected to each other, in series / parallel, forming several chains ("string" in English) of cells. Electrical connection elements 22, for example made of copper, make it possible to ensure the electrical connections between the cells 20 in each chain.

[0039] The photovoltaic module M may comprise a frame (not shown), for example in aluminum, arranged on the periphery of the stack to stiffen the module M. For the implementation of the invention described below, this frame, as well as the electrical junction box (not shown) generally fixed on the rear face of the module M, are previously removed. The method of the invention is in fact dedicated more particularly to the treatment of the stack of layers of the photovoltaic module M.

[0040] The invention relates more particularly to the disassembly of the rear layer 1 of the photovoltaic module M and its detachment from the rest of the photovoltaic module.

[0041] For this disassembly, the photovoltaic module advantageously rests by its front face 30 against a support 6. In a non-limiting manner, the photovoltaic module can be held against this support 6 by mechanical means (clamping for example) or by suction-type means.

[0042] The support 6 is advantageously made of a metallic material. Peeling tool

[0043] [Fig.3]

[0044] [Fig.4]

[0045] To peel off the rear layer 1 from the photovoltaic module M, the system of the invention comprises a specific tool 4 onto which this rear layer 1 is wound.

[0046] This tool 4 has an elongated shape along a so-called longitudinal axis (X). It can take the form of a rod, a roller, a blade, etc. Its cross-section can be circular, square, or of any shape. The tool has a length at least equal to the length or width of the rear layer 1 of the photovoltaic module so that it can be wound onto the tool 4.

[0047] Along its longitudinal axis, the tool 4 advantageously comprises a slot 40 intended to receive a corner or an edge of the rear layer to be removed. The slot 40 extends over a sufficient length to receive this corner or this edge.

[0048] According to a particular aspect of the invention, the tool 4 incorporates heating means 4L. In other words, these heating means 41 make it possible to heat the external surface of the tool to a given temperature, which makes it easier to take off during winding.

[0049] The temperature is chosen to be sufficient to allow at least partial softening of the intermediate encapsulation layer 2 to which the rear layer 1 adheres, by melting it, thus allowing easier detachment of the rear layer 1. Conventionally, this temperature is between 90°C and 150°C, for example around 100°C.

[0050] The heating means are for example of the induction type, of the resistive type or equivalent. The temperature is for example adjustable to plus or minus 5°C.

[0051] Tool 4 firstly allows the rear layer (preheated - see below) then hold it firmly and then roll it up on its external surface. The holding of the back layer 1 on the tool 4 can be mechanical or carried out using a vacuum grip.

[0052] To power the heating means 41, the system comprises an electrical power source, external or internal to the tool 4. Preheating device

[0053] [Fig.4]

[0054] According to a particular aspect of the invention, to initiate the detachment of the rear layer 1, the system advantageously comprises a preheating device 5. This preheating device 5 makes it possible to carry out localized heating of the corner or edge of the rear layer 1 of the photovoltaic module M, in order to detach it and grip it to insert this corner or edge into the slot 40 of the tool 4. Thanks to this device, the intermediate encapsulation layer 2 is advantageously softened in a determined zone, advantageously downstream or at the position of the tool 4 during the winding of the rear layer 1 onto the tool 4.

[0055] This preheating device 5 is for example arranged to heat an area of ​​the support 6 on which the photovoltaic module rests by its front face 30 or to heat directly on the side of the rear face 10 of the photovoltaic module M.

[0056] The preheating device 5 ultimately makes it possible to heat a more or less extensive surface area of ​​the photovoltaic module M.

[0057] The preheating device 5 can for example heat the entire support 6 so as to cover the entire surface of the photovoltaic module.

[0058] It can also heat a smaller area of ​​the support 6, the photovoltaic module M and / or the preheating device being for example moved as the rear layer 1 is detached to make the area being detached coincide with the area of ​​the support 6 which is heated by the preheating device 5. This principle also applies when the heating is carried out on the side of the rear face 10 of the photovoltaic module M.

[0059] In a non-limiting manner, the preheating device may be produced in the form of infrared lamps or heating means operating by induction (in particular when the support 6 is metallic).

[0060] Rotation of the tool and relative movement of the tool / photovoltaic module

[0061] [Fig.4]

[0062] In order to wind the rear layer onto the tool 4, the tool is mounted on the axis of a motor 42 in order to be driven in rotation on itself.

[0063] Furthermore, the winding of the rear layer 1 on the tool 4 is enabled by a translational movement of the tool 4 and / or of the photovoltaic module M following a direction of advance (Y) which is perpendicular to the longitudinal axis of the tool 4 and parallel to the plane of the photovoltaic module M.

[0064] Advantageously, it should be noted that the removal of the rear layer, by peeling, is improved when the peel angle (corresponding to the angle formed by the direction of traction during removal) is between 90° and 180°, and advantageously equal to 180°. With a peel angle of 180°, it was noted that the rear layer 1 was kept intact after removal, thus facilitating its recycling after removal. Disassembly process

[0065] [Fig.5]

[0066] [Fig.6]

[0067] In connection with [Fig.5], the method of peeling off the rear layer 1 of the photovoltaic module M comprises the steps described below.

[0068] El: At least localized heating of a corner or an edge of the photovoltaic module M to initiate detachment. This corner or this edge therefore corresponds to that by which the rear layer 1 will begin to be removed from the rest of the photovoltaic module M.

[0069] The localized heating is carried out using the preheating device 5, adjusted to ensure that the photovoltaic module M is at a sufficient temperature (for example approximately 100°C for EVA) to allow the material forming the intermediate encapsulation layer 2 to soften.

[0070] E2: Once the edge or corner has been detached, it is inserted and held in the slot 40 of the detachment tool 4.

[0071] E3: The tool 4 is heated by its integrated heating means. It is actuated in rotation so as to rotate around its axis. The tool 4 and / or the photovoltaic module M is moved in translation along the direction of advance (Y) so as to gradually wind the rear layer 1 around the tool 4. The preheating device 5 can be kept active to heat a particular area of ​​the photovoltaic module, for example that located just downstream of the tool 4 during the take-off process, or the entire photovoltaic module.

[0072] E4: The entire rear layer 4 is peeled off from the photovoltaic module M and wrapped around the tool 4. After removal, this layer 1 does not contain any residue of the intermediate encapsulation layer 2, which allows its recycling and recovery.

[0073] It should be noted that separation may be more complicated when the material of the encapsulation layer is a crosslinked polymer such as, for example, EVA. When this material is a non-crosslinked polymer, such as, for example, polyolefins, separation is easier.

[0074] Once the rear layer 1 has been removed, it is possible to remove the remaining layers of the photovoltaic module.

[0075] In connection with [Fig.6], the intermediate encapsulation layer 2 can thus be removed by machining, for example by sanding using an abrasive belt 60 or for example by localized milling. The known disassembly techniques for removing these remaining layers can thus be implemented. It is then possible to recover the active elements of the initial module in the form of chips 200 which could then be processed in order to recover the metals of interest.

[0076] The solar glass of the front layer 3 can be reinjected into the manufacture of photovoltaic modules or other applications.

[0077] The fluorinated compounds contained in the rear layer 1 may be treated in a specialized process.

[0078] The metals contained in the cells (silicon, silver, aluminum, indium, etc.) can be recovered and recycled.

[0079] The EVA of the intermediate layer 2 can be reused in the manufacture of floor mats, shoe soles, etc.

[0080] A subsequent step of cleaning the tool 4 may also be provided. This involves, for example, burning the material of the intermediate encapsulation layer 2 which could have been deposited on the tool 4 during detachment.

[0081] The invention thus presents numerous advantages: - Simple solution for removing the back layer 1, without risk of tearing this back layer 1; - Simple and clean removal, without residue from the intermediate layer 2; - No degradation of the intermediate layer 2, which can thus be removed by another technique (machining / sanding or other); - Recovery of the back layer 1 in the form of a roll, easily usable for recycling and recovery;

Claims

Claims

1. Method for disassembling a photovoltaic module, said photovoltaic module comprising: - A rear layer (1) forming a first protective element on the rear face of the photovoltaic module (M), this rear layer being made from at least one polymer material, - An intermediate layer, interposed between the rear layer (1) and a front layer (3), and comprising an encapsulation envelope (21) in which photovoltaic cells (20) are placed, - The front layer (3) forming a second protective element on the front face of the photovoltaic module (M), - The method comprising a step of winding the rear layer around a tool (4) to detach it from the intermediate layer, - Characterized in that the tool (4) is heated in a localized manner by heating means integrated into the tool (4) during the implementation of the winding step.

2. Method according to claim 1, characterized in that it comprises a step of adjusting the temperature of the tool (4), said temperature being chosen to at least partially melt said intermediate layer.

3. Method according to claim 1 or 2, characterized in that it comprises a prior step of detaching a corner or an edge of the rear layer, by preheating.

4. Method according to claim 3, characterized in that the preheating is implemented by localized heating of the photovoltaic module.

5. Method according to one of claims 1 to 4, characterized in that it comprises a subsequent step of removing the intermediate layer (2) by sanding using an abrasive belt.

6. System for disassembling a photovoltaic module, used to implement the method as defined in one of claims 1 to 5, said photovoltaic module comprising: - A rear layer (1) forming a first element of protection on the rear face of the photovoltaic module (M), this rear layer (1) being made from at least one polymer material, - An intermediate layer, interposed between the rear layer (1) and a front layer (3) and comprising an encapsulation envelope (21) in which photovoltaic cells (20) are placed, - The front layer (3) forming a second protective element on the front face of the photovoltaic module (M), - Characterized in that it comprises: - A tool (4) capable of detaching the rear layer (1) from the intermediate layer, said rear layer (1) being intended to wrap around the tool when it is detached, - Heating means integrated into the tool (4).

7. System according to claim 6, characterized in that said tool (4) has an elongated shape along a longitudinal axis and comprises a slot (40) extending along its longitudinal axis, forming a receiving housing for a corner or an edge of said rear layer (1).

8. System according to claim 6 or 7, characterized in that the heating means (41) integrated into the tool are of the induction type.

9. System according to one of claims 6 to 8, characterized in that it comprises means for adjusting the temperature of the tool, said temperature being chosen to at least partially melt said intermediate layer of the photovoltaic module.

10. System according to one of claims 6 to 9, characterized in that it comprises a support (6) on which the photovoltaic module rests, by its front face.

11. System according to claim 10, characterized in that it comprises a preheating device (5) arranged to heat at least one zone of the support (6) or arranged to directly heat the rear layer (1) of the photovoltaic module.

12. System according to claim 11, characterized in that the preheating device comprises one or more infrared lamps or induction heating means.

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