METHOD FOR DISASSEMBLING THE BACK LAYER OF A PHOTOVOLTAIC MODULE

Description

Technical field of the invention

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

[0002] A photovoltaic module contains photovoltaic cells designed to convert solar energy into electrical energy.

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

[0004] Typically, a photovoltaic module takes the form of a panel composed of three superimposed layers fixed together: A back layer (called "backsheet") forming a first protective element on the rear face; A second layer, called the intermediate layer; this intermediate layer contains the photovoltaic cells, the electrical connections 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 as to allow the captured light rays to pass through;

[0005] Several methods have already been considered for recycling photovoltaic modules. One method involves crushing the entire module and then subjecting it to various thermal and / or chemical treatments to separate the materials that make up its composition, such as glass, silver, copper, silicon, etc. However, this first method is energy-intensive and not very environmentally friendly.

[0006] Patent application WO2019 / 043329A1 proposes an alternative method for disassembling a photovoltaic module. This method involves removing each layer of the module and separating it by cutting it with an abrasive wire. Each removed layer can then be processed separately to recover the materials of interest. However, this method has some drawbacks. It requires several separate processing stations, first for cutting and then for grinding each removed layer.

[0007] French patent application FR3017551A1 proposes a method for removing the back layer and the first encapsulation film, thus exposing the photovoltaic cells, which remain attached to the second encapsulation film. This removal is achieved by heating the photovoltaic module from below, peeling back a corner of the assembly formed by the back layer and the encapsulation film, and rolling the assembly to detach it. 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 for the removal of only the back layer of the photovoltaic module. Furthermore, heating the intermediate layer to high temperatures (over 300°C) is likely to lead to the release of fluorinated compounds.

[0009] Patent application no. FR3070541A1 describes the detachment of the back layer of the PV panel by progressive separation.

[0010] The aim of the invention is to propose a solution allowing the removal of only the back layer of a photovoltaic module, the solution allowing a simple and clean removal of this layer, without tearing it, limiting the release of fluorinated compounds and allowing then recovery of said layer and disassembly of the other layers of the module.

[0011] The invention notably allows for a clean detachment of the back layer, meaning that no residue of the back layer remains on the intermediate encapsulation layer after removal, allowing for improved recycling of the different layers and materials of the photovoltaic module. Description of the invention

[0012] This goal is achieved by a process of disassembling a photovoltaic module, said photovoltaic module comprising: A back layer forming a first protective element on the rear face of the photovoltaic module, this back 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 process comprising: A preliminary step of peeling off a corner or an edge of the back layer, A step of winding the back layer around a tool to detach it from the intermediate layer, The tool being heated locally during the winding step, A step of adjusting the temperature of the tool, said temperature being chosen to melt at least partially said intermediate layer.

[0013] According to another particularity, the preliminary step of detaching a corner or an edge of the back layer is carried out by preheating.

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

[0015] Another distinctive feature of the process is that it involves a subsequent step of removing the intermediate layer by sanding with an abrasive belt.

[0016] The invention also relates to a system for disassembling a photovoltaic module, used to implement the process as defined above, said photovoltaic module comprising: A back layer forming a first protective element on the rear face of the photovoltaic module, this back layer being made of 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 system comprising: Means for initiating the removal of the back layer, A tool capable of separating the back layer from the intermediate layer, said back layer being intended to wrap around the tool during its separation, Heating means integrated into the tool.

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

[0018] Another distinctive feature is that the heating elements integrated into the tool are of the induction type.

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

[0020] Another distinctive feature of the system is that it includes a support on which the photovoltaic module rests, by its front face.

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

[0022] According to another feature, the preheating device includes one or more infrared lamps or induction heating means. Brief description of the figures

[0023] Other features and advantages will appear in the detailed description that follows, in conjunction with the attached drawings, in which: There figure 1 represents, in perspective view, a multilayer architecture of a photovoltaic module; The figure 2 represents, in cross-section, the multilayer architecture of a photovoltaic module; The figure 3 shows an example of an embodiment of the tool used in the disassembly system of the invention; The figure 4schematically illustrates the principle of disassembling the back layer of the photovoltaic module, implemented using the disassembly system of the invention; The figure 5 shows the different stages of the invention's process; The figure 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 Figure 1 Figure 2 Figure 4

[0024] In the following description, the front face of the photovoltaic module M corresponds to a face of the module receiving light rays and the rear face corresponds to the face opposite the front face.

[0025] In the following description, each layer of the photovoltaic module has two opposite faces, a first face oriented towards the back and a second face oriented towards the front.

[0026] The photovoltaic module has two main opposite faces, a first face 10 oriented towards the rear and a second face 30 oriented towards the front.

[0027] Hereafter, "protective element" means an element that can provide a stiffening function and / or a surface protection function.

[0028] With reference to the figure 1 and to the figure 2 As is known, a photovoltaic module consists of several superimposed layers assembled together: A back layer 1 (commonly called "backsheet") forming a first protective element on the rear face of the photovoltaic module; this back layer is usually made of a polymer-type material; An intermediate layer 2, interposed between the back layer and the front layer (described below), allowing the assembly of one side of the back layer and the other side of the front layer; this intermediate layer includes the photovoltaic cells 20, the electrical connectors 22 and an encapsulation casing 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 the one exposed to light rays;

[0029] It should be noted that in the attached figures, the photovoltaic module M is shown upside down, so that its rear face 10 is located above and its front face 30 is located below.

[0030] For readability in the attached figures, the different layers of the module are not shown to scale. For example, the back layer 1 may be a few hundred µm thick (for example, about 350µm), the intermediate layer 2 may be up to 1mm thick, and the front layer 3 may be about 3 to 4mm thick.

[0031] The back layer 1 can provide, in particular, gas and water impermeability, electrical protection / insulation, and mechanical protection. This back layer 1 can be made from a fluoropolymer. This could be polyvinyl fluoride (PVF), for example, marketed under the name TEDLAR (registered trademark) by DuPont (registered trademark).

[0032] Without limitation, the back layer 1 may itself be composed of a stack of several layers: a layer of PVF, a layer of PET (ethylene poly(terephthalate)), a layer of PVF.

[0033] In the intermediate layer 2, the encapsulation layer 21 is typically made of a polymer such as EVA (Ethylene-Vinyl Acetate), forming a material to which the back layer 1 can adhere on one side and the front layer 3 on the other, allowing the three layers to be joined together. The three layers can be joined by hot lamination, so that the back and front layers adhere to the encapsulation layer material, 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 (POE), or an ionomer.

[0034] In the intermediate layer 2, the photovoltaic cells 20 are generally connected together in series / parallel, forming several strings of cells. Electrical connection elements 22, for example made of copper, provide the electrical connections between the cells 20 in each string.

[0035] The photovoltaic module M may include a frame (not shown), for example made of aluminum, arranged around 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 to the rear face of the module M, are first removed. The method of the invention is in fact specifically dedicated to the treatment of the layer stack of the photovoltaic module M.

[0036] The invention relates more particularly to the disassembly of the back layer 1 of the photovoltaic module M and its detachment from the rest of the photovoltaic module.

[0037] For this disassembly, the photovoltaic module advantageously rests its front face 30 against a support 6. Without limitation, the photovoltaic module can be held against this support 6 by mechanical means (clamping for example) or by means of suction type.

[0038] Support 6 is advantageously made of a metallic material. peeling tool Figure 3 Figure 4

[0039] To detach the back layer 1 of the photovoltaic module M, the system of the invention includes a specific tool 4 onto which this back layer 1 is wound.

[0040] This tool 4 has an elongated shape along a longitudinal axis (X). It can be a rod, a roller, a blade, etc. Its cross-section can be circular, square, or any other shape. The tool has a length at least equal to the length or width of the back layer 1 of the photovoltaic module so that the latter can be wound around the tool 4.

[0041] Along its longitudinal axis, the tool 4 advantageously includes a slot 40 for receiving a corner or edge of the back layer to be removed. The slot 40 extends over a sufficient length to receive this corner or edge.

[0042] According to the invention, the tool 4 incorporates heating means 41. 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 peel off during winding.

[0043] The temperature is chosen to be sufficient to soften at least partially the intermediate encapsulation layer 2 onto which the back layer 1 adheres, by melting it, thus allowing easier detachment of the back layer 1. Classically, this temperature is between 90°C and 150°C, for example around 100°C.

[0044] The heating methods used are, for example, induction, resistive, or equivalent. The temperature is adjustable to within ±5°C.

[0045] Tool 4 is used first to lift the back layer (advantageously by preheating – see below) and then to hold it firmly before rolling it onto its outer surface. The back layer 1 can be held onto tool 4 mechanically or using a vacuum grip. Preheating can be used to initiate the removal of the back layer, but other methods could be considered (mechanical means, for example).

[0046] To power the heating means 41, the system includes an electrical power source, external or internal to the tool 4. Preheating device Figure 4

[0047] According to a particular aspect of the invention, to initiate the detachment of the back layer 1, the system advantageously includes a preheating device 5. This preheating device 5 makes it possible to perform localized heating of the corner or edge of the back layer 1 of the photovoltaic module M, in order to detach it and grasp it so that this corner or edge can be inserted into the slot 40 of the tool 4. Thanks to this device, the intermediate encapsulation layer 2 is advantageously softened in a determined area, advantageously downstream or at the position of the tool 4 during the winding of the back layer 1 onto the tool 4.

[0048] This preheating device 5 is arranged for example to heat an area of ​​the support 6 on which the photovoltaic module rests by its front face 30 or to heat directly the side of the rear face 10 of the photovoltaic module M. The preheating device 5 ultimately allows to heat a more or less extensive surface of the photovoltaic module M.

[0049] The preheating device 5 can, for example, heat the entire support 6 so as to cover the entire surface of the photovoltaic module.

[0050] It can also heat a smaller area of ​​the support 6, the photovoltaic module M and / or the preheating device being moved, for example, as the back layer 1 is peeled off, to make the area being peeled off coincide with the area of ​​the support 6 that is heated by the preheating device 5. This principle also applies when the heating is carried out on the rear face 10 of the photovoltaic module M.

[0051] By way of non-limitation, the preheating device may be in the form of infrared lamps or induction heating means (particularly when the support 6 is metallic). Tool rotation and relative tool / photovoltaic module movement Figure 4

[0052] In order to wrap the back layer onto the tool 4, the tool is mounted on the shaft of a motor 42 so that it is driven to rotate on itself.

[0053] Furthermore, the winding of the back layer 1 on the tool 4 is enabled by a translational movement of the tool 4 and / or the photovoltaic module M along 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.

[0054] Advantageously, it should be noted that the removal of the back layer by peeling is improved when the peeling 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 peeling angle of 180°, it was observed that the back layer 1 remained intact after removal, thus facilitating its recycling. Disassembly process Figure 5 Figure 6

[0055] In connection with the figure 5 The process of peeling off the back layer 1 of the photovoltaic module M involves the steps described below.

[0056] E1: At least localized heating of a corner or edge of the photovoltaic module M to initiate delamination. This corner or edge therefore corresponds to the point from which the rear layer 1 will begin to be removed from the rest of the photovoltaic module M.

[0057] Localized heating is achieved using the preheating device 5, set to ensure that the photovoltaic module M is at a sufficient temperature (for example, around 100°C for EVA) to soften the material forming the intermediate encapsulation layer 2.

[0058] E2: Once the edge or corner has been detached, it is inserted and held in slot 40 of the detachment tool 4.

[0059] E3: The tool 4 is heated by its integrated heating means. It is rotated so as to turn around its axis. The tool 4 and / or the photovoltaic module M is moved in translation along the forward direction (Y) so as to progressively wrap the back 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 the area just downstream of the tool 4 during the peeling process, or the entire photovoltaic module.

[0060] E4: The entire back layer 4 is peeled off the photovoltaic module M and wrapped around the tool 4. After removal, this layer 1 has no residue of the intermediate encapsulation layer 2, which allows its recycling and recovery.

[0061] It should be noted that separation can be more complicated when the encapsulation layer material is a cross-linked polymer such as EVA. When this material is a non-cross-linked polymer, such as polyolefins, separation is easier.

[0062] Once the back layer 1 has been removed, it is possible to remove the remaining layers of the photovoltaic module.

[0063] In connection with the figure 6 The intermediate encapsulation layer 2 can thus be removed by machining, for example by sanding with a 60 grit abrasive belt or by localized milling. Known disassembly techniques for removing these remaining layers can then be implemented. It is then possible to recover the active elements of the original module as 200 grit chips, which could then be processed to recover the metals of interest.

[0064] The solar glass from the front layer 3 can be reintroduced into the manufacture of photovoltaic modules or other applications. The fluorinated compounds contained in the back layer 1 can be treated in a specialized channel.

[0065] The metals contained in the cells (silicon, silver, aluminum, indium...) can be recovered and recycled.

[0066] The EVA from the intermediate layer 2 can be reused in the manufacture of floor mats, shoe soles, etc.

[0067] A subsequent cleaning step for tool 4 may also be planned. This could involve, for example, burning off any material from the intermediate encapsulation layer 2 that may have been deposited on tool 4 during detachment.

[0068] The invention thus offers numerous advantages: Simple solution for removing the back layer 1, without risk of tearing this back layer 1; Simple and clean removal, without residue of the intermediate layer 2 deposit; No degradation of the intermediate layer 2, which can therefore 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

1. Method for disassembling a photovoltaic module, said photovoltaic module comprising: - a back layer (1) forming a first protective element on the back face of the photovoltaic module (M), this back layer being made based on at least one polymer material, - an intermediate layer interposed between the back layer (1) and a front layer (3) and comprising an encapsulating 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 back layer around a tool (4) in order to detach it from the intermediate layer, - the method also comprising a prior step of detaching a corner or edge of the back layer, characterized in that: - the tool (4) is heated in a localized manner by heating means integrated in the tool (4) during the implementation of the winding step, - the method comprises a step of adjusting the temperature of the tool (4), said temperature being chosen so as to at least partially melt said intermediate layer.

2. Method according to Claim 1, characterized in that the prior step of detaching the corner or edge of the back layer is implemented by preheating.

3. Method according to Claim 2, characterized in that the preheating is implemented by localized heating of the photovoltaic module.

4. Method according to any of Claims 1 to 3, characterized in that it comprises a subsequent step of removing the intermediate layer (2) by sanding with the aid of an abrasive belt.

5. System for disassembling a photovoltaic module, employed to implement the method as defined in any of Claims 1 to 4, said photovoltaic module comprising: - a back layer (1) forming a first protective element on the back face of the photovoltaic module (M), this back layer (1) being made based on at least one polymer material, - an intermediate layer interposed between the back layer (1) and a front layer (3) and comprising an encapsulating 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), - said system for disassembling the photovoltaic module comprising: - means for initiating the removal of the back layer, - a tool (4) capable of detaching the back layer (1) from the intermediate layer, said back layer (1) being intended to be wound around the tool during its detachment, characterized in that said system for disassembling the photovoltaic module also comprises: - heating means integrated in the tool (4), - means for adjusting the temperature of the tool, said temperature being chosen so as to at least partially melt said intermediate layer of the photovoltaic module.

6. System according to Claim 5, characterized in that said tool (4) has an elongate shape along a longitudinal axis and has a slot (40) extending along its longitudinal axis, forming an accommodating housing for a corner or edge of said back layer (1).

7. System according to Claim 5 or 6, characterized in that the heating means (41) integrated in the tool are of the induction type.

8. System according to any of Claims 5 to 7, characterized in that it comprises a support (6) on which the photovoltaic module comes to bear by way of its front face.

9. System according to Claim 8, characterized in that it comprises a preheating device (5) arranged to heat at least a zone of the support (6) or arranged to directly heat the back layer (1) of the photovoltaic module.

10. System according to Claim 9, characterized in that the preheating device comprises one or more infrared lamps or induction heating means.