Processing method for recycling a photovoltaic module

Abstract

Process for recycling a photovoltaic module. Process for recycling a functional device, in particular a photovoltaic module (M), the functional device comprising at least one of a photovoltaic cell (20) or a light-emitting diode (LED) embedded in an encapsulant (21) comprising a polymer material, the process comprising the following steps: (a) irradiation of the functional device by an ionizing treatment modifying the mechanical properties of the encapsulant, and (b) machining of the encapsulant (21) to reduce it to chips. Figure for the abstract: Fig. 4

Description

Title of the invention: Processing method for recycling a photovoltaic module technical field

[0001] The present invention relates to a treatment method for recycling a functional device, in particular a photovoltaic module. The functional device comprises at least one of a photovoltaic cell or a light-emitting diode (LED) embedded in an encapsulant comprising a polymer material. Prior art

[0002] A functional device, such as a photovoltaic module, comprises cells photovoltaics designed to convert solar energy into electrical energy, or light-emitting diodes designed to convert electrical energy into light energy.

[0003] Such a functional device contains many interesting materials to recover and valorize, when the functional device is at the end of its life or malfunctioning.

[0004] For the purpose of its recycling, various solutions are known for separating the different materials that compose it, but these can be energy-intensive and not very environmentally friendly.

[0005] A method for disassembling a photovoltaic module is known, in particular from international application WO 2019 / 043329. This method consists of 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 can be quite slow due to the ductility of the encapsulating polymer material used, namely ethylene-vinyl acetate (EVA).

[0006] There is a need to further improve and facilitate the recycling of a functional device, in particular a photovoltaic module. Summary of the invention

[0007] The invention thus relates, according to one of its aspects, to a treatment method for recycling a functional device, in particular a photovoltaic module, the functional device comprising at least one of a photovoltaic cell or a light-emitting diode (LED) embedded in an encapsulant comprising a polymer material, the method comprising the following steps:

[0008] (a) irradiation of the functional device by an ionizing treatment modifying the mechanical properties of the encapsulant, and

[0009] (b) machining of the encapsulant, in order to reduce it to chips. Functional device

[0010] The term "functional device" means a device comprising a multilayer stack comprising at least:

[0011] - a transparent protective layer disposed on the front face, for example made of glass,

[0012] - an encapsulant made of polymer material, for example of the transparent elastomer type, in which is encapsulated or coated at least one electrically or optically active element, such as photovoltaic cells or light-emitting diodes (LEDs), and

[0013] - a protective layer disposed on the rear face of the device, for example in glass as well, or for example based on multi-layer polymers defining a non-transparent back face, called a "backsheet".

[0014] The functional device may include at least one photovoltaic cell or a light-emitting diode.

[0015] This may be a photovoltaic module. The photovoltaic module as such comprises photovoltaic cells arranged between a front face and a rear face, and which are electrically connected to each other by connecting conductors and immersed between two front and rear layers of encapsulation material, both of which form an encapsulation.

[0016] In the absence of irradiation, the polymer material of the encapsulant may exhibit rubbery mechanical behavior, as is notably the case with EVA. Such behavior can make machining more difficult, as ductile tearing is slower than brittle tearing. Irradiation makes the polymer material more brittle, facilitating its machining and reduction to chips. Machining can be faster and easier. Indeed, irradiating the polymer material modifies its physical properties, particularly its mechanical properties. The polymer material becomes more brittle, more rigid, and less elastic.

[0017] The treatment for recycling the functional device is easier to implement and less expensive. It avoids using too much energy or producing effluents. Encapsulating

[0018] The encapsulating assembly can be formed from at least one front film and one back film comprising at least one polymer-type encapsulating material selected from: acid copolymers, ionomers, poly(ethylene-vinyl acetate) (EVA), vinyl acetals, such as polyvinyl butyrals (PVB), polyurethanes, polyethylenes, such as linear low-density polyethylenes, polyolefin elastomer copolymers, α-olefin copolymers and α-,[3-ethylenic carboxylic acid esters, such as ethylene-methyl acrylate copolymers and ethylene-butyl acrylate copolymers, silicone elastomers and / or elastomers based on crosslinked thermoplastic polyolefin.

[0019] By the term "encapsulating" or "encapsulated", it is to be understood that the plurality of photovoltaic cells or LEDs is arranged in a volume, for example hermetically sealed with respect to liquids and gases, at least partly formed by at least two films of encapsulating material(s), joined together after lamination to form the encapsulating assembly.

[0020] Indeed, initially, that is to say before any lamination operation, the encapsulating assembly consists of at least two films of encapsulating material(s), between which the plurality of photovoltaic cells or LEDs is encapsulated.

[0021] However, during the film lamination operation, the encapsulation material films melt to form, after the lamination operation, only one solidified assembly in which the photovoltaic cells or LEDs are embedded.

[0022] A photovoltaic module may have two protective layers, the first protective layer forming, for example, the front face and made of one or more transparent materials chosen from the following, non-limiting list: glass, composite material, plastic, polymer. A photovoltaic module may have a second protective layer forming the rear face and made of one or more materials chosen from the following, non-limiting list: glass, composite material, plastic, polymer, metals. If both the first and second protective layers are made of glass, it is called a double-glass module. Description of the invention Machining

[0023] Machining step (b) takes place after irradiation step (a). Irradiating the device with ionizing radiation facilitates its subsequent machining. The invention makes it possible, for example, to facilitate the dismantling of the functional device, such as a photovoltaic module, and thus to facilitate its recycling. The materials of interest from the functional device can therefore be more easily recovered for recycling.

[0024] Machining step (b) is mechanical. Machining step (b) may include at least one of the following: cutting, in particular with an abrasive wire, milling, grinding, in particular with an abrasive belt or grinding wheel. The abrasive wire may be diamond-coated.

[0025] Machining step (b) can, for example, be implemented using the method described in patent application WO 2019 / 043329. Irradiation facilitates the movement of the abrasive wire or abrasive belt, or any other method of mechanical cutting or machining.

[0026] Milling can make it possible to remove the encapsulant and separate it from the photovoltaic cells.

[0027] The process may include an additional step (c) of collecting the chips obtained in the machining step (b).

[0028] The chips obtained can have a size half, or even three times smaller, than the size of the chips obtained without irradiation, under constant machining conditions.

[0029] By using diamonds of average size 100 pm, the chips obtained can have a size of less than 60 pm, better less than 50 pm, or even less than 40 pm, being for example on the order of 30 pm, with a reference size of 70 pm without irradiation.

[0030] The small size of the chips obtained shows that, thanks to irradiation, the machining is more brittle than ductile.

[0031] In the invention, the machining step is not implemented to bring an object to the desired dimensions, nor to give it a particular shape, but to form chips of the polymer material of the encapsulant, in order to harvest materials of interest with a good yield and to valorize them.

[0032] The resulting wood chips, usually treated as waste or scrap, can, thanks to the invention, be a source of valuable materials. The invention enables their recycling and gives a new life to the materials that make up the functional device. The materials can be processed separately and reused.

[0033] The polymer material of the encapsulant, for example EVA, can be reused in the manufacture of products such as floor mats, shoe soles, this list not being exhaustive.

[0034] The polymer material may comprise a transparent elastomer, in particular comprising an ethylene-vinyl acetate (EVA) or a polyolefin elastomer (POE), in particular polyisobutylene (PIB), ethylene-propylene (EPR or EPM) or ethylene-propylene-diene monomer (EPDM). Ionizing treatment

[0035] Ionizing treatment makes it possible to modify the mechanical properties of the polymer material, in order to facilitate its machining.

[0036] Ionizing treatment can produce on the one hand new bonds or cross-links in the polymer material, this can be a cross-linking phenomenon, which has the effect of stiffening it, and on the other hand can break chains in the polymer material, this can be a depolymerization phenomenon, which can weaken it and thus facilitate its machining.

[0037] The ionizing treatment may include at least one of gamma radiation, X-rays, beta radiation, an electron beam, this list not being exhaustive.

[0038] The use of a focused electron beam can advantageously facilitate the focusing of the ionizing treatment, and thus better direct the treatment, particularly towards the encapsulant rather than towards the protective layers of the device functional.

[0039] The ionizing treatment can be configured so that the dose absorbed by the functional device, in particular by the encapsulant, is greater than 20 kGy (kiloGray), or even greater than 30 kGy, preferably greater than 40 kGy, and especially greater than 50 kGy, for example, being on the order of 90 kGy. Such irradiation makes it possible to modify the mechanical properties of the encapsulant satisfactorily.

[0040] The ionizing treatment can be configured so that the dose absorbed by the functional device, in particular by the encapsulant, is less than 150 kGy (kiloGray), or even less than 130 kGy, better less than 120 kGy, in particular less than 100 kGy, being for example in the order of 90 kGy.

[0041] Such irradiation makes it possible not to affect the other layers of the device, in particular the protective layers, in particular the protective layer located on the back face of the device, for example based on multi-layer polymers defining a non-transparent back face, known as the "backsheet".

[0042] Furthermore, the polymers used for this protective layer may be more resistant to irradiation and less weakened by it than the polymer material of the encapsulant. Thus, the protective layer can be reused, if necessary, in its initial state.

[0043] The ionizing treatment can be configured so that the dose absorbed by the functional device, in particular by the encapsulant, is between 20 and 150 kGy, or even between 30 and 120 kGy, better between 40 and 100 kGy.

[0044] In particular, the adhesion properties of the polymer material to the protective layers can be reduced, for example by 25 to 40% for a glass protective layer, and by 10 to 22% for a polymer-based protective layer.

[0045] These modifications can in particular make it easier to machine, in particular with regard to the motor torque of the machining, the deflection of the cutting wire and in general the machining parameters, in particular the speed.

[0046] The machining speed can be at least twice, or even three times, higher than the machining speed without irradiation, under constant machining conditions.

[0047] The machining speed can be greater than 50 mm / min, or even greater than 60 mm / min, better than 70 mm / min, being for example in the order of 80 to 150 mm / min, with a reference speed without irradiation of 200 mm / min, under constant machining conditions.

[0048] The machining speed can be greater than 400 mm / min, or even greater than 500 mm / min, better than 600 mm / min, being for example in the order of 700 mm / min, with a reference speed without irradiation of 200 mm / min, under constant machining conditions.

[0049] In the process, at machining step (b), more chips can be collected by mass than without irradiation, under constant machining conditions, in particular more than 5%, or even more than 10%, better yet more than 15%, or even more than 20% of chips by mass. In one embodiment, more than 30%, or even more than 35% of chips by mass, can be collected than without irradiation, under constant machining conditions.

[0050] In the process, at machining step (b), more chips by volume can be collected than without irradiation, under constant machining conditions, in particular more than 20%, or even more than 30%, better yet more than 40%, or even more than 50% of chips by volume. In one embodiment, more than 60%, or even more than 70% of chips by volume can be collected than without irradiation, under constant machining conditions.

[0051] The invention also relates, independently or in combination with the above, to a method for recycling a photovoltaic module, comprising the implementation of the treatment method as described above for disassembling the photovoltaic module.

[0052] The invention also relates, independently or in combination with the foregoing, to a processing installation for recycling a functional device, in particular a photovoltaic module, the functional device comprising at least one of a photovoltaic cell or a light-emitting diode (LED) embedded in an encapsulant comprising a polymer material, in particular for implementing the process as described above, the installation comprising:

[0053] - a device for irradiating the functional device by ionizing treatment, in order to to modify the mechanical properties of the encapsulant, and

[0054] - a machining device for the encapsulant, in order to reduce it to chips.

[0055] The irradiation device can be configured to allow irradiation of the functional device from the side of the glass protective layer, or alternatively from the side of the multi-layer polymer-based protective layer.

[0056] The irradiation device can be configured to allow the functional device to be irradiated substantially perpendicularly to it. This makes it possible to obtain more homogeneous irradiation.

[0057] The machining device may include at least one of: an abrasive wire, an abrasive belt, a grinding wheel, a milling cutter, this list not being exhaustive.

[0058] The installation may include means for collecting the chips obtained in step (b) of machining. Brief description of the drawings

[0059] The invention will be better understood upon reading the detailed description that follows, the non-limiting examples of embodiments thereof, and upon examination of the accompanying drawing, on which:

[0060] [Fig.1] Fig.1 is a schematic and partial perspective view of a photovoltaic module.

[0061] [Fig.2] The [Fig.2] is a schematic and partial cross-sectional view of the photovoltaic module of the [Fig.1].

[0062] [Fig.3] The [Fig.3] is a block diagram illustrating the process according to the invention.

[0063] [Fig.4] [Fig.4] is a view analogous to [Fig.2] of the implementation of the process according to the invention. Detailed description

[0064] Figures 1 and 2 illustrate a photovoltaic module M comprising several superimposed layers assembled together:

[0065] - A first protective layer 1 (commonly called "backsheet") facing rear; this first protective layer 1 is usually made from multi-layer polymers; it can be opaque or transparent, single-layer or multi-layer;

[0066] - A second layer 2, called the intermediate layer, interposed between the first layer and the third layer 3, described below, allowing the assembly of one side of the first protective layer 1 and the other side of the third protective layer 3; this intermediate layer comprising photovoltaic cells 20, electrical connectors 22 and an encapsulant 21 arranged around the photovoltaic cells;

[0067] - A third protective layer 3 on the front face; this third layer of Protection 3 is usually made of glass, for example, clear tempered glass approximately 3 to 4 mm thick.

[0068] It should be noted that in the accompanying figures, the photovoltaic module M is shown upside down, so that its rear face is on top and its front face is on the bottom. For the sake of clarity in the figures, the different layers of the module are not shown to scale. For example, the first layer 1 may have a thickness of a few hundred micrometers, for example about 350 µm, the second layer 2 may have a thickness of up to 1 mm, and the third layer 3 may have a thickness of about 3 to 4 mm.

[0069] 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. The two protective layers 1 and 3 may have a stiffening function and / or a surface protection function.

[0070] The first layer 1 can, in particular, provide a gas and water impermeability function, an electrical protection / insulation function, and a mechanical protection function. This first layer 1 can be made from a fluorinated polymer. It This could be polyvinyl fluoride (PVF), for example marketed under the name TEDLAR (registered trademark) by DuPont (registered trademark). Without limitation, the first layer 1 may itself be composed of a stack of several layers: a layer of PVF, a layer of PET (polyethylene terephthalate), and another layer of PVF.

[0071] In the intermediate layer 2, the encapsulant 21 is conventionally made of a polymer such as EVA (Ethylene-Vinyl Acetate), forming a material to which the first layer 1 can adhere on one side and the third layer 3 on the other, allowing the three layers to be joined together. The three layers can be joined together by hot lamination, so that the first and third layers adhere to the encapsulant material 21, thus forming a single-piece stack.

[0072] In the intermediate layer 2, the photovoltaic cells 20 are connected to each other 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.

[0073] 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, this frame, as well as the electrical junction box (not shown) generally fixed on the rear face of the module M, may be removed beforehand.

[0074] The invention relates to the recycling of the photovoltaic module M, comprising the implementation of a treatment process which will now be described in more detail, with reference to [Fig. 3]. The treatment process for recycling the photovoltaic module M comprises the following steps:

[0075] (a) irradiation of the photovoltaic module M by an ionizing treatment modifying the mechanical properties of encapsulant 21, and

[0076] (b) machining of the encapsulant 21, in order to reduce it to chips.

[0077] The ionizing treatment in step (a) modifies the mechanical properties of the polymer material of the encapsulant 21, thereby facilitating its machining. The ionizing treatment comprises at least one of the following: gamma radiation, X-rays, beta radiation, or an electron beam, this list being non-exhaustive. The ionizing treatment can be configured so that the dose absorbed by the photovoltaic module M, in particular by the encapsulant 21, is between 20 and 150 kGy, or even between 30 and 120 kGy, preferably between 40 and 100 kGy. Such irradiation satisfactorily modifies the mechanical properties of the encapsulant 21.

[0078] The polymer material of the encapsulant 21 can, in the absence of irradiation, exhibit rubbery-type mechanical behavior, which is notably the case for EVA. Such behavior can make machining more difficult, as ductile pull-out is slower than brittle pull-out. Irradiation makes the polymer material more brittle, facilitating its machining and reduction to chips. Machining can be faster and easier. Indeed, irradiating the polymer material modifies its physical properties, particularly its mechanical properties. The polymer material becomes more brittle and less elastic.

[0079] Such irradiation prevents the other layers, particularly the protective layers, especially the protective layer 1 located on the rear face, from being affected. Furthermore, the polymers used for this protective layer may be more resistant to irradiation and less weakened by it than the polymer material of the encapsulant 21. Thus, the protective layer 1 can be reused, if necessary, in its initial state.

[0080] Machining step (b) is mechanical. In the described example, machining step (b) comprises cutting with an abrasive wire 12. The abrasive wire 12 may be diamond-coated. Machining step (b) may, for example, be carried out using the method described in patent application WO 2019 / 043329.

[0081] Furthermore, the process includes an additional step (c) of collecting the chips obtained in the machining step (b). The chips obtained are half, or even a third, the size of the chips obtained without irradiation, under constant machining conditions. Using diamonds with an average size of 100 µm, the chips obtained can be on the order of 30 µm, with a reference size of 70 µm without irradiation. The small size of the chips obtained shows that, thanks to irradiation, the machining is more brittle than ductile.

[0082] In machining step (b), more chips are collected by mass than without irradiation, under constant machining conditions, specifically more than 5%, or even more than 10%, better yet more than 15%, or even more than 20% of chips by mass. In one embodiment, more than 30%, or even more than 35%, of chips by mass can be collected compared to without irradiation, under constant machining conditions.

[0083] In machining step (b), more chips are collected by volume than without irradiation, under constant machining conditions, specifically more than 20%, or even more than 30%, better yet more than 40%, or even more than 50% of the chips by volume. In one embodiment, it is possible to collect more than 60%, or even more than 70%, of the chips by volume compared to without irradiation, under constant machining conditions.

[0084] The treatment process of the invention is implemented using a suitable treatment plant 30, as illustrated in [Fig. 4]. The treatment plant for recycling a photovoltaic module M comprises:

[0085] - an irradiation device 31 for the photovoltaic module M by a treatment ionizing, in order to modify the mechanical properties of the encapsulant 21, and

[0086] - a machining device 32 for the encapsulant 21, in order to reduce it to chips.

[0087] The irradiation device 31 is configured to allow irradiation of the photovoltaic module M from the side of the protective glass layer 3. For this purpose, the installation 30 includes a support 15 on which the photovoltaic module M is positioned. The irradiation device 31 is configured to allow irradiation of the functional device substantially perpendicular to it, as illustrated by the arrows. This results in more homogeneous irradiation.

[0088] The machining device 32 includes a cutting tool 17 having, for example, an abrasive wire 12, arranged to allow cutting, in particular dry cutting, of the encapsulant 21 in order to separate the photovoltaic cells 20 from it.

[0089] The height of the abrasive wire 12 relative to the support 15 is calculated to allow the desired cutting of the encapsulant 21 when the first protective layer 1 rests on the support 15. The support 15 can move while the cutting tool 17 remains fixed, notwithstanding the movement of the abrasive wire 12 to enable the cutting. Alternatively, the cutting tool 17 moves while the photovoltaic module M remains fixed. Thus, the installation can be configured to implement relative movement between the support 15 and the cutting tool 17 during the cutting of the encapsulant 21.

[0090] The installation may also include means for collecting the chips obtained in the machining step (b).

[0091] Everything described in the context of the processing method for recycling a functional device can be applied to the processing installation for recycling a functional device, and vice versa. In particular, the processing installation includes the hardware, and where applicable, the software, for implementing the processing method. The process and installation described above have an industrial application in the context of disassembling one or more photovoltaic modules for the purpose of recycling their components. Indeed, where applicable, it is then possible to recover the glass in its entirety if it is not broken, to recover the material containing the polymer material, and to recover the active elements of the photovoltaic module, such as the photovoltaic cells, which could be reused.

Claims

Demands

1. Process for recycling a functional device, in particular a photovoltaic module (M), the functional device comprising at least one of a photovoltaic cell (20) or a light-emitting diode (LED) embedded in an encapsulant (21) comprising a polymer material, the process comprising the following steps: (a) irradiation of the functional device by an ionizing treatment modifying the mechanical properties of the encapsulant, and (b) machining of the encapsulant (21), in order to reduce it to chips.

2. A method according to the preceding claim, wherein the machining step (b) comprises at least one of: cutting, in particular by an abrasive wire (12), milling, grinding, in particular by means of an abrasive belt or a grinding wheel.

3. A method according to any one of the preceding claims, comprising an additional step (c) of collecting the chips obtained in the machining step (b).

4. A process according to any one of the preceding claims, the chips obtained having a size half, or even three times smaller, than the size of the chips obtained without irradiation, under constant machining conditions.

5. A process according to any one of the preceding claims, the chips obtained having a size of less than 60 pm, preferably less than 50 pm, or even less than 40 pm, being for example on the order of 30 pm, with a reference size of 70 pm without irradiation.

6. A method according to any one of the preceding claims, the polymer material comprising a transparent elastomer, in particular comprising an ethylene-vinyl acetate (EVA) or a polyolefin elastomer (POE), in particular polyisobutylene (PIB), ethylene-propylene (EPR or EPM) or ethylene-propylene-diene monomer (EPDM).

7. A method according to any one of the preceding claims, the ionizing treatment comprising at least one of gamma radiation, X-rays, beta radiation, electron beam, this list not being exhaustive.

8. A method according to any one of the preceding claims, the ionizing treatment being configured so that the dose absorbed by the functional device, in particular by the encapsulant (21), i.e. greater than 20 kGy (kiloGray), or even greater than 30 kGy, better greater than 40 kGy, in particular greater than 50 kGy.

9. A method according to any one of the preceding claims, the ionizing treatment being configured so that the dose absorbed by the functional device, in particular by the encapsulant (21), is less than 150 kGy (kiloGray), or even less than 130 kGy, better less than 120 kGy, in particular less than 100 kGy.

10. A method according to any one of the preceding claims, wherein the machining speed is at least twice, or even three times, higher than the non-irradiated machining speed, under constant machining conditions.

11. A method according to any one of the preceding claims, wherein the machining speed is greater than 50 mm / min, or even greater than 60 mm / min, better greater than 70 mm / min, being in particular in the order of 80 to 150 mm / min, being even better greater than 400 mm / min, or even greater than 500 mm / min, better greater than 600 mm / min, being for example in the order of 700 mm / min, with a reference speed without irradiation of 200 mm / min, under constant machining conditions.

12. A method according to any one of the preceding claims, wherein in the machining step (b) more chips are collected by mass than without irradiation, under constant machining conditions, in particular more than 5%, or even more than 10%, better more than 15%, or even more than 20% chips by mass.

13. A method according to any one of the preceding claims, wherein in the machining step (b) more chips are collected by volume than without irradiation, under constant machining conditions, in particular more than 20%, or even more than 30%, better more than 40%, or even more than 50% of chips by volume.

14. A method for recycling a photovoltaic module, comprising implementing the treatment method according to any one of the preceding claims for disassembling the photovoltaic module (M).

15. Processing installation (30) for recycling a functional device, in particular a photovoltaic module (M), the functional device comprising at least one of a photovoltaic cell or a light-emitting diode (LED) embedded in an encapsulant (21) comprising a polymer material, in particular for the implementation of the method according to any one of the preceding claims, the installation (30) comprising: - an irradiation device (31) for the functional device by ionizing treatment, in order to modify the mechanical properties of the encapsulant (21), and - a machining device (32) for the encapsulant, in order to reduce it to chips.

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