Photovoltaic module and method for disassembling the same

Abstract

The present application relates to the technical field of photovoltaic modules, and particularly relates to a photovoltaic module and a disassembling method thereof. The photovoltaic module comprises a photovoltaic glass, a cell sheet and an encapsulating adhesive film arranged between the photovoltaic glass and the cell sheet. An easy-to-disassemble coating is further arranged between the photovoltaic glass and the encapsulating adhesive film. The easy-to-disassemble coating comprises a base soluble in a solvent and expanded microspheres uniformly dispersed in the base. According to the present application, the easy-to-disassemble coating is arranged between the photovoltaic glass and the encapsulating adhesive film, and the easy-to-disassemble coating contains a large number of expanded microspheres, so that a large number of pores can be formed by heating to an expansion temperature. Then, the solvent can permeate into the pores to effectively and quickly separate the encapsulating adhesive film from the photovoltaic glass. The separation process does not cause damage to the photovoltaic glass and the cell sheet due to the low heating temperature, thereby realizing efficient and non-damage recycling of the photovoltaic glass and the cell sheet.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module technology, and more specifically to a photovoltaic module and its disassembly method. Background Technology

[0002] With the rapid growth of global photovoltaic (PV) power generation capacity, the need for recycling and processing used PV modules is becoming increasingly urgent. Existing PV modules typically use ethylene-vinyl acetate copolymer (EVA) or polyolefin elastomer (POE) as encapsulating film to press-encapsulate the PV glass and solar cells together. This encapsulating film bonds the PV glass and solar cells, creating a tight chemical bond and physical interlocking between them. This bonding method provides a strong connection and meets the reliability requirements for long-term outdoor use of PV modules.

[0003] However, the aforementioned strong bonding method becomes an obstacle to disassembly during the recycling and processing of photovoltaic modules. Existing technologies can disassemble and separate photovoltaic modules using chemical swelling. However, existing chemical swelling methods are limited by the tight interfacial bond between the encapsulating film and the photovoltaic glass, making it difficult for the solvent to penetrate quickly. The separation process is diffusion-controlled, resulting in a very slow processing speed (usually requiring several hours or even days). To shorten the swelling time, current research generally requires first breaking the photovoltaic module to increase the contact area between the solvent and the encapsulating film, thereby accelerating solvent penetration. However, breaking the module leads to the loss of the integrity of the photovoltaic glass, and the mechanical stress generated by the excessive swelling of the encapsulating film during chemical swelling may still cause damage to the solar cells. Summary of the Invention

[0004] To address the technical problem of existing technologies that struggle to balance disassembly time and effective recycling of components when using chemical swelling to disassemble photovoltaic modules, this invention provides a photovoltaic module and its disassembly method.

[0005] This invention employs the following technical solution: A photovoltaic module includes photovoltaic glass, solar cells, and an encapsulating film sandwiched between the photovoltaic glass and the solar cells. An easily removable coating is also provided between the photovoltaic glass and the encapsulating film. The easily removable coating includes a solvent-soluble matrix and expanded microspheres uniformly dispersed within the matrix; the mass ratio of the expanded microspheres to the matrix is ​​1:99 to 1:19. The expanded microspheres located within the matrix rupture due to volume expansion after reaching their expansion temperature, thereby forming channels at the interface between the easily removable coating and the photovoltaic glass; the photovoltaic glass and the encapsulating film are separated by immersion in a solvent, with the solvent permeating into the easily removable coating through the channels.

[0006] As a further improvement of the present invention, the expansion temperature of the expanded microspheres is higher than the lamination temperature of the photovoltaic module; the expansion temperature of the expanded microspheres is 160℃~180℃.

[0007] As a further improvement of the present invention, the expanded microspheres have a core-shell structure, with the outer shell of the expanded microspheres being thermoplastic acrylic resin and the core of the expanded microspheres being a physical foaming agent.

[0008] As a further improvement of the present invention, the matrix is ​​a resin that is soluble in a solvent; the light transmittance of the resin is greater than 90%.

[0009] As a further improvement of the present invention, the solvent is either anhydrous ethanol or ethyl acetate.

[0010] As a further improvement of the present invention, the resin includes one or more of methyl methacrylate, polyurethane, and polyvinyl butyral.

[0011] As a further improvement of the present invention, the particle size range of the expanded microspheres is 30~40μm.

[0012] As a further improvement of the present invention, the thickness of the easily removable coating is 40~50μm.

[0013] As a further improvement of the present invention, the solvent soaking temperature is 50-60℃ and the soaking time is 20-30 minutes.

[0014] This invention also includes a method for disassembling a photovoltaic module as described above, comprising: heating the photovoltaic module to its expansion temperature and maintaining this temperature for 10-15 minutes; cooling the heated photovoltaic module to room temperature and then immersing it in a solvent; removing the module every 5 minutes and manually peeling it from the photovoltaic glass and the encapsulating film, and making the following judgments: if the photovoltaic glass and the encapsulating film cannot be peeled apart, continue immersing the module in the solvent and removing it every 5 minutes to peel it apart until the photovoltaic glass and the encapsulating film are separated before proceeding to the next step; if the photovoltaic glass and the encapsulating film can be manually peeled apart, proceed to the next step. The encapsulating film and the solar cell are then separated by mechanical processing, thereby obtaining the separated photovoltaic glass, encapsulating film, and solar cell.

[0015] As a further improvement of the present invention, the encapsulating film and the battery cell are separated by the following mechanical processing method: First, the battery cell encapsulated in the encapsulating film is manually cut. The cut battery cell is then ground into a powder mixture, and the powder mixture is sieved to obtain the battery cell powder.

[0016] As a further improvement of the present invention, the grinding process is carried out by planetary ball milling, and grinding balls with diameters of 15mm, 10mm and 0.3-0.4mm are used in sequence for graded grinding.

[0017] As a further improvement of the present invention, a 200-mesh sieve is used to sieve the powder mixture.

[0018] As a further improvement of the present invention, the immersion temperature during solvent immersion is 50°C.

[0019] The technical solution provided by this invention has the following beneficial effects: (1) The photovoltaic module provided by this solution has an easy-to-disassemble coating between the photovoltaic glass and the encapsulating film. The easy-to-disassemble coating contains a lot of expandable microspheres, which can form a lot of channels when heated to the expansion temperature. The solvent can then penetrate into the channels to quickly and effectively separate the encapsulating film and the photovoltaic glass. The separation process will not damage the photovoltaic glass and the solar cells because the heating temperature is low. Thus, the disassembly time of the photovoltaic module is greatly shortened while ensuring that the components in the photovoltaic module can be effectively recycled after disassembly.

[0020] (2) The photovoltaic module provided by this solution, by limiting the substrate to a resin that can be dissolved in a solvent, allows the solvent to penetrate into the easy-to-disassemble coating and the interface between the easy-to-disassemble coating and the photovoltaic glass through the channels when the heated photovoltaic module is placed in the solvent. At the same time, the solvent can also dissolve the substrate of the easy-to-disassemble coating. The two can work together to accelerate the separation speed between the encapsulation film and the photovoltaic glass, thereby greatly improving the separation efficiency between the photovoltaic glass and the encapsulation film.

[0021] (3) The photovoltaic module disassembly method provided in this solution involves an easy-to-disassemble coating between the photovoltaic glass and the encapsulating film. The expandable microspheres within this coating expand at an expansion temperature to form channels. Combined with ethyl acetate immersion, this allows for the separation of the photovoltaic glass and the encapsulating film under mild conditions, with a separation time of 20-30 minutes, yielding a complete photovoltaic glass. This solution enables the photovoltaic module to simultaneously achieve a complete photovoltaic glass while significantly reducing the disassembly time, effectively solving the technical problem in existing technologies where it is difficult to simultaneously balance disassembly time and the effective recycling of disassembled components. Attached Figure Description

[0022] Figure 1 This is a partial structural schematic diagram of a photovoltaic module provided in Embodiment 1 of the present invention.

[0023] Figure 2 This is a schematic diagram of the internal structure of the expanded microspheres in Embodiment 1 of the present invention.

[0024] Figure 3 This is a flowchart of the steps of the photovoltaic module disassembly method provided in Embodiment 2 of the present invention.

[0025] Figure 4 This is a bar chart showing the average light transmittance of photovoltaic modules made with different amounts of expanded microspheres, as presented in the performance testing section of this invention.

[0026] The following are labeled in the diagram: 1. Photovoltaic glass; 2. Easy-to-disassemble coating; 3. Encapsulation film; 4. Solar cell; 5. Expanded microspheres; 6. Core; 7. Outer shell. Detailed Implementation

[0027] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0028] In the description of this invention, it should be noted that directional terms such as "center," "lateral," "longitudinal," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific scope of protection of this invention. The terms "first," "second," etc., in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The terms "comprising" and "having," and any variations thereof, in the specification and claims of this invention, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0029] Example 1 This embodiment provides a photovoltaic module, such as... Figure 1As shown, it includes photovoltaic glass 1, solar cells 4, and an encapsulating film 3 sandwiched between the photovoltaic glass 1 and the solar cells 4. The encapsulating film 3 can be used to bond the photovoltaic glass 1 and the solar cells 4 using common existing methods. The encapsulating film 3 can be selected from any one of EVA film, POE film, and EPE film. The side of the photovoltaic glass 1 facing the encapsulating film 3 is coated with an easy-to-remove coating 2, which includes a solvent-soluble matrix and expandable microspheres 5 uniformly dispersed in the matrix. The expandable microspheres 5 located in the matrix rupture due to volume expansion after the temperature reaches their expansion temperature, thereby forming channels at the interface between the easy-to-remove coating 2 and the photovoltaic glass 1. When disassembling the photovoltaic module in this solution, the module is first heated to the expansion temperature of the expanding microspheres 5 and maintained at that temperature for a period of time. Based on this heating to the expansion temperature and maintenance, most of the expanding microspheres 5 within the easily removable coating 2 rupture due to volume expansion, thus forming numerous channels within the easily removable coating 2 and at the interface between the easily removable coating 2 and the photovoltaic glass 1. The heated photovoltaic module is then immersed in a solvent. The solvent penetrates between the photovoltaic glass 1 and the encapsulating film 3 through the channels formed by the ruptured expanding microspheres 5. The solvent entering the easily removable coating 2 not only inserts into the polymer chains of the encapsulating film 3, causing it to swell, but this uneven swelling also generates significant internal stress within the encapsulating film 3 and at the interface between the encapsulating film 3 and the photovoltaic glass 1, thereby achieving the separation of the encapsulating film 3 and the photovoltaic glass 1. Furthermore, the solvent entering the easily removable coating 2 can also disrupt the interfacial adhesion between the encapsulating film 3 and the photovoltaic glass 1, causing the adhesion to fail and resulting in separation. The expansion temperature of the expandable microspheres 5 is set to be higher than the lamination temperature of the photovoltaic module. In this solution, the expansion temperature range of the expandable microspheres 5 is 160-180℃. The purpose of limiting it to this range is twofold: First, by limiting the expansion temperature of the expandable microspheres 5 to be higher than the lamination temperature of the photovoltaic module, which is generally higher than its operating temperature, this setting ensures that the expandable microspheres 5 within the easily detachable coating 2 remain relatively stable and do not expand during the assembly or normal operation of the photovoltaic module, thus preventing any impact on the use of the photovoltaic module. Second, by setting the expansion temperature of the expandable microspheres 5 to 160-180℃, this temperature range is not too high, ensuring that the expansion of the expandable microspheres 5 triggered by heating will not damage the photovoltaic glass 1 and the solar cell 4. This effectively solves the problem in the prior art where photovoltaic modules need to be separated at a high temperature of 350℃, resulting in the photovoltaic glass 1 being prone to local carbonization and the solar cell 4 being prone to cracking after high-temperature separation, thus damaging the photovoltaic glass 1 and solar cell 4 after high-temperature separation and making them unrecyclable.As described above, this solution provides an easily removable coating 2 between the photovoltaic glass 1 and the encapsulating film 3. The easily removable coating 2 contains many expandable microspheres 5, which can form many channels when heated to the expansion temperature. Solvents can then penetrate into the channels to quickly and effectively separate the encapsulating film 3 and the photovoltaic glass 1. The separation process does not damage the photovoltaic glass 1 and the solar cell 4 due to the low heating temperature, thus achieving efficient and non-damaging recycling of the photovoltaic glass 1 and the solar cell 4.

[0030] The mass ratio of the expanded microspheres 5 to the substrate is 1:99 to 1:19. By limiting the mass ratio of the expanded microspheres 5 to the substrate within the above range, it is possible to ensure that a large number of expanded microspheres 5 are uniformly dispersed in the substrate while minimizing the impact on the light transmittance of the photovoltaic module. This allows the expanded microspheres 5 to rupture as much as possible when the heating temperature reaches the expansion temperature, thereby forming a large number of channels within the easily removable coating 2 and at the interface between the easily removable coating 2 and the photovoltaic glass 1. These channels can be interconnected, thereby accelerating the solvent penetration rate through the channels and further improving the separation speed between the photovoltaic glass 1 and the encapsulating film 3.

[0031] It is understandable that the expansion temperature can be the lowest temperature at which the expanded microsphere 5 begins to expand in volume.

[0032] The particle size of the expanded microspheres 5 is in the range of 30-40 μm. By limiting the particle size within this range, while minimizing the impact on the light transmittance of the photovoltaic module, the expanded microspheres 5 can form larger channels at the interface between the easily removable coating 2 and the photovoltaic glass 1 after heating to the expansion temperature. This allows the easily removable coating 2 to "accommodate" more solvent, thereby further accelerating the separation speed between the photovoltaic glass 1 and the encapsulating film 3.

[0033] In this design, the thickness of the easily removable coating 2 is 40-50 μm. Limiting the thickness of the easily removable coating 2 to this range allows it to "accommodate" more expanded microspheres 5 between the photovoltaic glass 1 and the encapsulating film 3 while minimizing interference with the light transmittance of the photovoltaic module. This accelerates the solvent penetration rate and ultimately speeds up the separation between the photovoltaic glass 1 and the encapsulating film 3. Furthermore, the particle size of the expanded microspheres 5 is 30-40 μm, slightly smaller than the thickness of the easily removable coating 2. By designing the thickness of the easily removable coating 2 to be slightly larger than the particle size of the expanded microspheres 5, most of the pores formed after the expanded microspheres 5 in the easily removable coating 2 rupture due to volume expansion when heated to the expansion temperature can communicate with the interface between the photovoltaic glass 1 and the encapsulating film 3. This accelerates the separation rate of the photovoltaic glass 1 and the encapsulating film 3 when the solvent penetrates through the pores.

[0034] The substrate can be a solvent-soluble resin. Firstly, after the photovoltaic module is heated to its expansion temperature and held for a period of time, numerous channels are formed within the easily removable coating 2 and between the easily removable coating 2 and the encapsulating film 3 due to the presence of the expanded microspheres 5. This solution further limits the substrate to a solvent-soluble resin, allowing the solvent to penetrate not only into the easily removable coating 2 and at the interface between the easily removable coating 2 and the photovoltaic glass 1 through the channels when the heated photovoltaic module is placed in the solvent. Simultaneously, the solvent can also dissolve the substrate of the easily removable coating 2. These two processes work synergistically to accelerate the separation speed between the encapsulating film 3 and the photovoltaic glass 1, thereby significantly improving the separation efficiency between the photovoltaic glass 1 and the encapsulating film 3.

[0035] The resin has a light transmittance greater than 90%. This limitation aims to ensure that the easily removable coating 2 applied to the photovoltaic glass 1 facing the encapsulating film 3 does not affect the overall light transmittance of the photovoltaic module, thus allowing the photovoltaic module to normally collect light energy and generate photovoltaic power. The resin may include one or more of methyl methacrylate, polyurethane, and polyvinyl butyral. Among them, methyl methacrylate (PMMA) typically has a visible light transmittance of 92-93% and extremely low haze (≤1%). It exhibits stable spectral transmittance characteristics in the 400-1100nm wavelength range, which effectively reduces light reflection and scattering losses when absorbing light energy, thereby ensuring that it does not affect the photovoltaic power generation performance of the photovoltaic module. Furthermore, PMMA has a stable molecular chain structure, strong chemical inertness, and excellent resistance to ultraviolet aging. It also maintains excellent dimensional stability and performance under extreme climates ranging from -40℃ to 80℃, thereby improving the stability of the resulting easily removable coating 2. Polyurethane, with its unique molecular structure, exhibits strong resistance to ultraviolet radiation, effectively preventing yellowing and fading. Furthermore, its excellent light transmittance ensures it does not interfere with the power generation performance of photovoltaic modules. Polyvinyl butyral, on the other hand, possesses both excellent light transmittance and superior moisture barrier properties, effectively preventing moisture intrusion into the photovoltaic modules without interfering with their normal power generation, thus protecting the internal structure of the modules.

[0036] Please see Figure 2The expandable microsphere 5 can have a core-shell structure. The outer shell 7 of the expandable microsphere 5 can be thermoplastic acrylic resin, and the core 6 can be a physical foaming agent. By designing the expandable microsphere 5 with the aforementioned core-shell structure, when the photovoltaic module is heated to the expansion temperature and held for 10-15 minutes, the outer shell 7 of the expandable microsphere 5 softens, and the physical foaming agent inside vaporizes, causing the volume of the expandable microsphere 5 to expand irreversibly. After expansion, the expandable microsphere 5 will rupture, forming channels within the easily removable coating 2 and at the interface between the easily removable coating 2 and the photovoltaic glass 1. These channels provide pathways for subsequent solvent penetration.

[0037] The expanded microspheres 5 can be Matsumoto Microspere F-19D manufactured by Matsumoto Oils & Fats Co., Ltd. of Japan, with an expansion temperature of 160-170℃ and a particle size of 30-40μm.

[0038] Solvents such as ethyl acetate, anhydrous ethanol, or other non-toxic or low-toxic solvents commonly used for the chemical dismantling of photovoltaic glass 1 and encapsulating film 3 can be selected.

[0039] The solvent immersion temperature is 50℃. Setting the solvent immersion temperature to 50℃ accelerates the movement speed of solvent molecules, allowing them to penetrate into the pores more quickly. This temperature also effectively promotes the swelling of the polymer chains in the encapsulating film 3, thereby facilitating the separation between the photovoltaic glass 1 and the encapsulating film 3. Furthermore, setting the immersion temperature to 50℃ falls within the low-temperature treatment range. This not only accelerates the physical swelling and viscosity modification of the encapsulating film 3 to speed up the separation process, but also avoids damaging the encapsulating film 3. This helps maintain the structural integrity of the encapsulating film 3 and the solar cell 4, facilitating subsequent recycling of both.

[0040] Using PMMS resin as the matrix and Matsumoto Microspere F-19D expanded microspheres 5, an easily removable coating 2 was prepared according to the following method. The preparation process is as follows: (1) PMMA resin was dissolved in ethyl acetate to prepare a PMMA solution with a solid content of 10wt%; (2) Expanded microspheres 5 were added to the PMMA solution, and the ratio of the added mass of expanded microspheres 5 to the mass of PMMA resin was 3:97. The expanded microspheres 5 were then magnetically stirred for 30 minutes to make them uniformly dispersed in the PMMA solution to obtain a coating slurry. (3) The coating slurry was coated onto the laminated surface of the photovoltaic glass 1 by a scraping method, and the wet film thickness was controlled to be about 200μm. The coating was then dried at 80℃ for 24 hours to remove the solvent, thereby forming an easily removable coating 2 on the laminated surface of the photovoltaic glass 1.

[0041] Based on the above-described process for preparing the easily removable coating 2, this embodiment can also provide a method for preparing a photovoltaic module, which includes the following steps: preparing the easily removable coating 2 on the laminated surface of the photovoltaic glass 1 using the process for preparing the easily removable coating 2; then laminating the photovoltaic glass 1 coated with the easily removable coating 2, the encapsulating film 3, the battery cell 4, and the backsheet according to the conventional photovoltaic module structure in the prior art, with a lamination temperature of 140°C and a holding time of 15 minutes, thereby obtaining the photovoltaic module.

[0042] Example 2 Based on the photovoltaic module provided in Example 1, this example also provides a method for disassembling the photovoltaic module. Please see below. Figure 3 It includes the following steps: S1: Heat the photovoltaic module to its expansion temperature and maintain this temperature for 10-15 minutes. The photovoltaic module can be heated entirely in an oven during this process.

[0043] S2: Cool the heated photovoltaic module to room temperature, then immerse it in ethyl acetate. Every 5 minutes, remove the module and manually peel it from the encapsulating film, making the following judgment: If it cannot be peeled apart, continue immersing it in the solvent and peeling it every 5 minutes until the photovoltaic glass and encapsulating film separate before proceeding to the next step (i.e., step S3). If the photovoltaic glass and encapsulating film can be manually peeled apart, proceed to the next step (i.e., step S3).

[0044] In step S2, the specific operation of immersing the photovoltaic module in ethyl acetate is as follows: First, the photovoltaic module is immersed in ethyl acetate. Then, the ethyl acetate is heated to 50°C, and timing begins. The photovoltaic module is then immersed at 50°C. Furthermore, during this process, the disassembly time of the photovoltaic module can be statistically analyzed. The statistical disassembly time is defined as the period from when the ethyl acetate is heated to 50°C until the photovoltaic glass is manually peeled off from the encapsulating film. The disassembly time described in other parts of this solution is interpreted according to the above definition.

[0045] In step S2, the immersion effect of the photovoltaic module can be periodically checked by manually peeling it off every 5 minutes. This solution is based on setting an easily removable coating 2, which can expand and rupture under heating at 160-180℃, forming channels within the easily removable coating 2 and at the contact interface between the easily removable coating 2 and the photovoltaic glass 1. Combined with solvent immersion, the solvent can penetrate into the interior through the formed channels, thereby rapidly weakening the adhesion between the photovoltaic glass 1 and the encapsulating film 3, and accelerating the disassembly rate between the encapsulating film 3 and the photovoltaic glass 1.

[0046] S3: The encapsulating film 3 and the solar cell 4 are separated by mechanical processing to obtain the photovoltaic glass 1, encapsulating film 3 and solar cell 4 separated from each other. The mechanical processing process is as follows: (3.1) The solar cell 4, which is wrapped in the encapsulating film 3 after swelling and separation, is manually cut to obtain small pieces of the cut solar cell. The purpose of cutting is to reduce the size of the solar cell 4 and improve the efficiency of the subsequent grinding process. The choice of this size can ensure that the material of the solar cell 4 is fully broken, while effectively avoiding the problem of insufficient grinding or excessive equipment load caused by the size of the cut solar cell 4 in the early stage of grinding. In this embodiment, the small pieces of the cut solar cell can be square pieces with a side length of 10mm. (3.2) The small pieces of the cut solar cell are then ground by planetary ball milling. Different specifications of zirconia grinding balls are used to grind the small pieces of solar cell during the grinding process. Grinding balls with diameters of 15 mm, 10 mm and 0.3-0.4 mm can be used in sequence for graded grinding. Larger-sized grinding beads are mainly used to initially break up small pieces of solar cells, gradually transforming them from a blocky structure into granular form. Medium and small-sized grinding beads are then used to further grind the small pieces of solar cells to obtain a powder mixture with smaller particle size and more uniform distribution. Furthermore, during the grinding process, silicon-based solar cells 4, due to their brittleness, are easily broken into fine particles under mechanical action; while EVA encapsulation film 3, due to its good flexibility and ductility, is difficult to pulverize under grinding conditions and usually exists in a sheet-like or agglomerated state. Utilizing this difference in mechanical properties, preliminary separation of EVA encapsulation film 3 and solar cells 4 can be achieved without introducing chemical treatment. (3.3) After grinding, the resulting powder mixture is sieved through a 200-mesh sieve to further separate the encapsulation film 3 and the solar cells 4, thereby improving the purity and uniformity of the sample. By sieving through a 200-mesh sieve, larger EVA residues and insufficiently broken particles can be effectively removed, resulting in battery cell 4 powder with relatively uniform particle size and good dispersion, thereby achieving effective recycling of battery cell 4.

[0047] Performance testing To verify the performance of the photovoltaic module provided in this embodiment, the technicians conducted the following experiments.

[0048] Test Example 1 A photovoltaic module was prepared using PMMS resin as the matrix and Matsumoto Microspere F-19D expanded microspheres 5 as the matrix, according to the following preparation method. The preparation process is as follows: (1) PMMA resin was dissolved in ethyl acetate to prepare a PMMA solution with a solid content of 10wt%; (2) Expanded microspheres 5 were added to the PMMA solution, and the ratio of the added mass of expanded microspheres 5 to the mass of PMMA resin was 3:97, that is, the added amount of expanded microspheres 5 was 3wt% of the solid content of the easily removable coating. The expanded microspheres 5 were then uniformly dispersed in the PMMA solution by magnetic stirring for 30 minutes to obtain the coating slurry. (3) The coating slurry was coated onto the laminated surface of the photovoltaic glass 1 by scraping, and the wet film thickness was controlled to be about 200μm; then dried at 80℃ for 24 hours to remove the solvent, thereby forming an easily removable coating 2 on the laminated surface of the photovoltaic glass 1. (4) The photovoltaic glass 1 coated with the easy-to-remove coating 2, the encapsulating film 3, the battery cell 4, and the back sheet are laminated according to the conventional photovoltaic module structure in the prior art. The lamination temperature is 140°C and the lamination time is 15 minutes to obtain the photovoltaic module.

[0049] Test Example 2 The manufacturing process and flow of the photovoltaic module in Test Example 2 are exactly the same as those in Test Example 1. The difference is that the ratio of the mass of expanded microspheres 5 to the mass of PMMA resin is 5:95, that is, the amount of expanded microspheres 5 added is 5 wt% of the solid content of the easily removable coating.

[0050] Comparative Example 1 The manufacturing process and procedure of the photovoltaic module in Comparative Example 1 are exactly the same as those in Test Example 1. The difference is that the photovoltaic glass 1 is not coated with an easy-to-remove coating 2. The photovoltaic glass 1, encapsulating film 3, solar cell 4, and backsheet are directly laminated according to the conventional photovoltaic module structure in the existing technology. The lamination temperature is 140℃ and held for 15 minutes to obtain the photovoltaic module.

[0051] (I) Disassembly performance test The photovoltaic modules prepared in Test Example 1, Test Example 2 and Comparative Example 1 were disassembled to investigate the effect of the easily removable coating 2 on the separation speed between the photovoltaic glass 1 and the encapsulating film 3.

[0052] The disassembly time in the disassembly experiment is the time required from heating to 50°C until the photovoltaic glass 1 and the encapsulating film 3 are completely separated, in minutes.

[0053] The photovoltaic modules prepared in Test Example 1 can be disassembled and tested as follows: Disassembly Experiment 1: The photovoltaic module from Test Example 1 was placed in an oven and heated to 160°C for 15 minutes. After cooling to room temperature, the photovoltaic module was immersed in ethyl acetate and heated to 50°C. Timing was started, and the photovoltaic module was removed every 5 minutes for manual peeling. If the photovoltaic glass and the encapsulating film could not be separated, the module was immersed in the solvent and removed every 5 minutes for peeling until the photovoltaic glass and encapsulating film separated. The disassembly time was recorded as 30 minutes.

[0054] Disassembly Experiment 2: The photovoltaic module from Test Example 1 was directly immersed in ethyl acetate and soaked at 50°C for 30 minutes. At this time, the photovoltaic glass 1 and the encapsulating film 3 did not separate.

[0055] Disassembly Experiment 3: The photovoltaic module from Test Example 1 was placed in an oven and heated to 160°C for 15 minutes. Even after heating, applying external force directly could not separate the photovoltaic glass 1 from the encapsulating film 3.

[0056] The disassembly process of the photovoltaic module prepared in Test Example 2 is as follows: The photovoltaic module of Test Example 2 was placed in an oven and heated to 160°C for 15 minutes. After cooling the photovoltaic module to room temperature, it was immersed in ethyl acetate and heated to 50°C. Timing was started, and the photovoltaic module was removed every 5 minutes for manual peeling. If the photovoltaic glass and the encapsulating film could not be separated, it was immersed in the solvent and removed every 5 minutes for peeling until the photovoltaic glass and the encapsulating film were separated. The disassembly time was recorded, and the disassembly time was 20 minutes.

[0057] The disassembly process of the photovoltaic module prepared in Comparative Example 1 is as follows: The photovoltaic module of Comparative Example 1 is placed in a tube furnace and heated to 500℃ under a nitrogen atmosphere and a flow rate of 0.5 L / min, and held for 30 min. After the above treatment, the mass loss rate of the encapsulating film 3 of the photovoltaic module of Comparative Example 1 is over 99.9%, meaning that the photovoltaic glass 1 and the solar cell 4 can be separated at this point. However, during the pyrolysis process at 500℃, the encapsulating film 3 expands secondary and carbonizes, generating mechanical stress, which causes the solar cell 4 to form diagonal cracks along the crystal orientation and break, thus making it impossible to effectively recycle the photovoltaic glass 1 and the solar cell 4.

[0058] Analysis of the disassembly experiments conducted on the three different photovoltaic modules revealed that, based on the photovoltaic module provided by this solution, the easily removable coating 2 is provided between the photovoltaic glass 1 and the encapsulating film 3. The expandable microspheres 5 within the easily removable coating 2 expand at an expansion temperature to form channels. Combined with ethyl acetate immersion, the photovoltaic glass 1 and the encapsulating film 3 can be separated under mild conditions in 20-30 minutes, yielding a complete photovoltaic glass 1 after separation. This allows the photovoltaic module provided by this solution to simultaneously obtain a complete photovoltaic glass 1 while significantly shortening the disassembly time, effectively solving the technical problem in existing technologies where it is difficult to simultaneously achieve both disassembly time and the integrity of the photovoltaic glass 1. Furthermore, based on the total solid mass of the easily removable coating, the addition amount of expandable microspheres 5 in the easily removable coating 2 (3wt%~5wt%) can effectively disassemble the photovoltaic glass 1 and the encapsulating film 3, yielding a complete photovoltaic glass 1 after disassembly. Furthermore, when the amount of expanded microspheres 5 added changes from 3wt% to 5wt%, the disassembly time between photovoltaic glass 1 and encapsulating film 3 is shortened from 30 minutes to 20 minutes. This indicates that the higher the amount of expanded microspheres 5 added, the more pores are formed, the faster the solvent swelling rate, and the higher the disassembly efficiency between photovoltaic glass 1 and encapsulating film 3.

[0059] Looking at the results of the disassembly experiment 1 in Comparative Example 1, the traditional high-temperature disassembly method was used, with a disassembly temperature of 500℃ and a disassembly time of 30 minutes. Although this disassembly process was fast, the excessively high temperature during disassembly led to carbonization of the backsheet and breakage of the solar cells 4, making effective recycling impossible. Analysis of the results of the second disassembly experiment on the photovoltaic module of Test Example 1 shows that, in the second disassembly experiment, the photovoltaic module of Test Example 1 was not heated to its expansion temperature before being disassembled; instead, it was directly immersed in ethyl acetate. This prevented the expansion microspheres 5 within the easily removable coating 2 from forming channels through volume expansion, thus preventing acetic acid from effectively penetrating to the interface and consequently preventing separation between the photovoltaic module and the encapsulating film 3. Analysis of the results of the third disassembly experiment on the photovoltaic module of Test Example 1 shows that, in the third disassembly experiment, the photovoltaic module was only heated to its expansion temperature for 15 minutes without subsequent immersion in ethyl acetate. This resulted in the photovoltaic glass 1 and the encapsulating film 3 remaining firmly bonded and unable to be separated after the third disassembly experiment. The three sets of disassembly experiments conducted on Test Example 1 demonstrate that, in this solution, the photovoltaic module must first be heated to its expansion temperature and maintained for 10-15 minutes before being immersed in ethyl acetate to achieve separation of the photovoltaic glass 1 and the encapsulating film 3. Both steps are indispensable; their synergistic effect ensures the integrity of the photovoltaic glass 1 after disassembly while significantly shortening the disassembly time.

[0060] (II) Light transmittance performance test Five different photovoltaic modules were prepared according to the method described in Example 1.

[0061] Experimental Group 1: Photovoltaic modules were prepared using PMMS resin as the matrix and Matsumoto Microspere F-19D expanded microspheres 5 as the matrix, according to the following preparation method. The preparation process is as follows: (1) PMMA resin was dissolved in ethyl acetate to prepare a PMMA solution with a solid content of 10wt%; (2) Expanded microspheres 5 were added to the PMMA solution. The ratio of the added mass of expanded microspheres 5 to the mass of PMMA resin was 1:99, that is, the added amount of expanded microspheres 5 was 1wt% of the solid content of the easily removable coating. The expanded microspheres 5 were then uniformly dispersed in the PMMA solution by magnetic stirring for 30 minutes to obtain the coating slurry. (3) The coating slurry was coated onto the laminated surface of photovoltaic glass 1 by scraping method, and the wet film thickness was controlled to be about 200μm; then dried at 80℃ for 24 hours to remove the solvent, thereby forming an easily removable coating 2 on the laminated surface of photovoltaic glass 1. (4) The photovoltaic glass 1 coated with the easy-to-remove coating 2, the encapsulating film 3, the battery cell 4, and the back sheet are laminated according to the conventional photovoltaic module structure in the prior art. The lamination temperature is 140°C and the lamination time is 15 minutes to obtain the photovoltaic module.

[0062] The preparation method of the photovoltaic module in Experiment Group 2 is exactly the same as that in Experiment Group 1. The difference is that the ratio of the mass of expanded microspheres 5 to the mass of PMMA resin in Experiment Group 2 is 2:98, that is, the amount of expanded microspheres 5 added is 2wt% of the solid content of the easily disassembled coating.

[0063] The preparation method of the photovoltaic module in Experiment Group 3 is exactly the same as that in Experiment Group 1. The difference is that the ratio of the mass of expanded microspheres 5 to the mass of PMMA resin in Experiment Group 3 is 3:97, that is, the amount of expanded microspheres 5 added is 3wt% of the solid content of the easily disassembled coating.

[0064] The preparation method of the photovoltaic module in Experiment Group 4 is exactly the same as that in Experiment Group 1. The difference is that the ratio of the mass of expanded microspheres 5 to the mass of PMMA resin in Experiment Group 4 is 4:96, that is, the amount of expanded microspheres 5 added is 4wt% of the solid content of the easily disassembled coating.

[0065] The preparation method of the photovoltaic module in Experiment Group 5 is exactly the same as that in Experiment Group 1. The difference is that the ratio of the mass of expanded microspheres 5 to the mass of PMMA resin in Experiment Group 5 is 5:95, that is, the amount of expanded microspheres 5 added is 5wt% of the solid content of the easily disassembled coating.

[0066] The transmittance of the five photovoltaic modules prepared in experimental groups one through five was tested, and the results were obtained. Figure 4The light transmittance test can be conducted according to GB / T 29848-2013 "Ethylene-vinyl acetate copolymer (EVA) film for photovoltaic module encapsulation". Through the analysis of... Figure 4 Analysis of the data shows that the transmittance of the photovoltaic module decreases with increasing addition of expanded microspheres 5: from 91.04% at 1 wt% to 86.21% at 5 wt%. However, even with the highest content of expanded microspheres 5 (5 wt%), the average transmittance of the photovoltaic module remains above 86%; and when the content of expanded microspheres 5 is controlled within the range of 1~3 wt%, the average transmittance can be maintained at a relatively high level of 89.46%~91.04%. These results indicate that although the transmittance is slightly reduced after adding the easily removable coating 2 to the surface of the photovoltaic module, it still meets the conventional standard requirements for transmittance of photovoltaic modules, proving the feasibility of the easily removable coating 2 in ensuring the optical performance of the photovoltaic module. In practical applications, the amount of expanded microspheres 5 added can be selected according to the usage scenario of the photovoltaic module to ensure rapid disassembly while minimizing the impact on the transmittance of the photovoltaic module.

[0067] The basic principles, main features, and advantages of this invention have been described above. Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection claimed by this invention is defined by the appended claims and their equivalents.

Claims

1. A photovoltaic module, comprising photovoltaic glass (1), solar cells (4), and an encapsulating film (3) sandwiched between the photovoltaic glass (1) and the solar cells (4), characterized in that, It also includes an easily removable coating (2) coated between the photovoltaic glass (1) and the encapsulating film (3). The easily removable coating (2) includes a solvent-soluble matrix and expanded microspheres (5) uniformly dispersed in the matrix. The mass ratio of the expanded microspheres (5) to the matrix is ​​1:99 to 1:

19. The expanded microspheres (5) located in the matrix rupture by volume expansion after the temperature reaches their expansion temperature, thereby forming channels at the interface between the easily removable coating (2) and the photovoltaic glass (1). The photovoltaic glass (1) and the encapsulating film (3) are separated by immersing in a solvent and the solvent permeates into the easily removable coating (2) through the channels.

2. The photovoltaic module as described in claim 1, characterized in that, The expansion temperature of the expanded microspheres (5) is higher than the lamination temperature of the photovoltaic module; the expansion temperature of the expanded microspheres (5) is 160℃~180℃.

3. The photovoltaic module as described in claim 1, characterized in that, The expanded microsphere (5) has a core-shell structure. The outer shell (7) of the expanded microsphere (5) is thermoplastic acrylic resin, and the core (6) of the expanded microsphere (5) is a physical foaming agent.

4. The photovoltaic module as described in claim 1, characterized in that, The matrix is ​​a resin soluble in a solvent; the light transmittance of the resin is greater than 90%. And / or, the solvent is either anhydrous ethanol or ethyl acetate.

5. The photovoltaic module as described in claim 4, characterized in that, The resin includes one or more of methyl methacrylate, polyurethane, and polyvinyl butyral.

6. The photovoltaic module as described in claim 1, characterized in that, The particle size range of the expanded microspheres (5) is 30~40μm; And / or, the thickness of the easily removable coating (2) is 40~50μm.

7. The photovoltaic module as described in claim 1, characterized in that, The solvent is used for immersion at a temperature of 50-60°C for 20-30 minutes.

8. A method for disassembling a photovoltaic module as described in any one of claims 1-7, characterized in that, It includes: Heat the photovoltaic modules to their expansion temperature and hold for 10-15 minutes; The heated photovoltaic modules were first cooled to room temperature, then immersed in a solvent; every 5 minutes, they were removed and manually peeled off from the photovoltaic glass and encapsulating film, and the following judgments were made: If it cannot be peeled off, continue to soak it in the solvent and remove it every 5 minutes to peel it off until the photovoltaic glass is separated from the encapsulating film before proceeding to the next step; If the photovoltaic glass and the encapsulating film can be manually peeled apart, proceed to the next step: the encapsulating film (3) and the solar cell (4) are separated by mechanical processing, thereby obtaining the photovoltaic glass (1), the encapsulating film (3) and the solar cell (4) that are separated from each other.

9. The method for disassembling a photovoltaic module as described in claim 8, characterized in that, The encapsulation film (3) and the battery cell (4) are separated by the following mechanical process: First, the battery cell (4) encapsulated in the encapsulation film (3) is manually cut; The sheared battery cell (4) is ground into a powder mixture, and then the powder mixture is sieved to separate the battery cell (4) powder.

10. The method for disassembling a photovoltaic module as described in claim 8, characterized in that, The grinding process is carried out using a planetary ball mill, with grinding balls of diameters of 15mm, 10mm, and 0.3-0.4mm used in sequence for graded grinding. And / or, a 200-mesh sieve is used to sieve the powder mixture during sieving; And / or, the immersion temperature during solvent immersion is 50℃.

Images