Photovoltaic module packaging method and photovoltaic module

Abstract

The embodiment of the invention provides a packaging method of a photovoltaic module and the photovoltaic module, and relates to the technical field of photovoltaics. The packaging method comprises the steps that a first adhesive film, a battery string, a second adhesive film and a back plate are sequentially laid on a substrate to form a base body, and at least one of the first adhesive film and the second adhesive film comprises an adhesive layer with a first melting point; heating the matrix at a first preset temperature and vacuumizing, wherein the first preset temperature is greater than or equal to the first melting point; heating and laminating the matrix at a second preset temperature, wherein the second preset temperature is higher than the first preset temperature; and the base body is heated at a third preset temperature, so that the bonding layer is cross-linked and cured, and the third preset temperature is higher than the second preset temperature. According to the packaging method of the photovoltaic module provided by the embodiment of the invention, the fluidity of the bonding layer at the first preset temperature is relatively good, and pre-infiltration of the battery string can be realized, so that bubbles on the battery string are relatively few.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a method for packaging photovoltaic modules and a photovoltaic module. Background Technology

[0002] A photovoltaic (PV) module is a power generation unit formed by encapsulating a string of solar cells. The encapsulation process is a crucial step in PV module manufacturing, and its quality directly affects the PV module's power generation efficiency, reliability, and lifespan.

[0003] Related technologies provide a method for encapsulating photovoltaic modules, including: sequentially laying a first encapsulant film, a cell string, a second encapsulant film, and a glass backsheet on a glass substrate to form a module to be laminated; and vacuum heating and pressing the module to be laminated at a preset temperature to cure it.

[0004] However, due to the low melting points of the first and second adhesive films, they have poor fluidity when melting under the preset temperature conditions, resulting in a large number of air bubbles on the battery string. Summary of the Invention

[0005] This application provides a photovoltaic module encapsulation method and a photovoltaic module. The adhesive layer has good fluidity at a first preset temperature, which can achieve pre-wetting of the battery string, thereby reducing the number of air bubbles on the battery string.

[0006] In a first aspect, embodiments of this application provide a method for encapsulating a photovoltaic module, comprising:

[0007] A first adhesive film, a battery string, a second adhesive film, and a backplate are sequentially deposited on a substrate to form a matrix. At least one of the first adhesive film and the second adhesive film includes an adhesive layer, which has a first melting point.

[0008] The substrate is heated to a first preset temperature, and a vacuum is drawn in the area around the substrate to melt the adhesive layer and remove the air bubbles on the surface of the battery string. The first preset temperature is greater than or equal to the first melting point.

[0009] The substrate is heated at a second preset temperature and pressed with a preset pressure so that the adhesive layer fills the edge of the battery string. The second preset temperature is greater than the first preset temperature.

[0010] The substrate is heated to a third preset temperature to crosslink and cure the adhesive layer, and to bond at least one of the substrate and the backsheet to the battery string. The third preset temperature is greater than the second preset temperature.

[0011] In some possible implementations, the adhesive layer is a modified polyolefin elastomer layer with a melting point of 60°C to 80°C.

[0012] In some possible implementations, at least one of the first adhesive film and the second adhesive film further includes a barrier layer disposed between the adhesive layer and the battery string. The barrier layer is used to block moisture and has a second melting point that is greater than a first preset temperature, and the second preset temperature is greater than the second melting point.

[0013] In some possible implementations, the barrier layer is an ethylene-vinyl alcohol copolymer layer, an antioxidant polymer layer, a light stabilizer polymer layer, or a coupling agent polymer layer, and the melting point of the barrier layer is 110°C to 140°C.

[0014] In some possible implementations, at least one of the first and second films further includes a support layer disposed between the barrier layer and the battery string. The support layer has a third melting point, which is greater than a first preset temperature, and a second preset temperature is greater than the third melting point.

[0015] In some possible implementations, the support layer is a polyolefin elastomer layer or a polyethylene layer, with a melting point of 90°C to 140°C.

[0016] In some possible implementations, prior to the steps of heating the substrate at a second preset temperature in a vacuum environment and pressing the substrate with a preset pressure to fill the edges of the cell string with an adhesive layer, the photovoltaic module encapsulation method further includes:

[0017] Detect the vacuum level around the substrate;

[0018] If the vacuum level reaches the preset value, the temperature of the heating substrate will be increased from the first preset temperature to the second preset temperature.

[0019] In some possible implementations, after heating the substrate at a third preset temperature to crosslink and cure the adhesive layer, and bonding at least one of the substrate and backsheet to the cell string, the photovoltaic module encapsulation method further includes:

[0020] The temperature of the heated substrate is reduced from the third preset temperature to the first preset temperature at a first cooling rate.

[0021] The temperature of the heated substrate is reduced from the first preset temperature to room temperature at a second cooling rate, where the second cooling rate is greater than the first cooling rate.

[0022] In some possible implementations, the first cooling rate is 1°C / min to 4°C / min; the second cooling rate is 5°C / min to 10°C / min.

[0023] Secondly, embodiments of this application provide a photovoltaic module, which is manufactured using any of the photovoltaic module encapsulation methods provided in the first aspect.

[0024] The photovoltaic module encapsulation method and photovoltaic module provided in this application embodiment have a first preset temperature that is greater than or equal to the first melting point of the adhesive layer. The adhesive layer can be fully melted at this temperature. Since the first preset temperature is lower than the second preset temperature, that is, lower than the lamination temperature of the substrate, the adhesive layer is melted at a lower temperature before laminating the substrate, thereby achieving pre-wetting of the battery string.

[0025] When the adhesive layer melts at the first preset temperature, its viscosity is low and its fluidity is better than that at the lamination temperature. This low viscosity characteristic allows the adhesive layer to quickly wet the surface of the cell string with the assistance of a vacuum environment and rapidly fill the tiny gaps and depressions on the surface of the cell string. This efficiently removes most of the air bubbles from the surface of the cell string, avoiding the problem of too many air bubbles remaining on the surface of the cell string. As a result, the appearance quality of the photovoltaic module is improved, and it is not easy to generate local overheating phenomenon, i.e. hot spot effect, during long-term use. This also makes it less likely to cause delamination problems between the substrate and / or backsheet and the cell string.

[0026] Under the second preset temperature condition, the viscosity of the adhesive layer is relatively high. At this time, it is convenient to press the substrate under preset pressure in a vacuum environment, so that the adhesive layer can effectively fill the edge area of ​​the battery string, ensuring good lamination effect. At the same time, it can further remove residual air bubbles that were not completely removed in the pre-wetting stage. This realizes the process of removing air bubbles in two stages, making the degassing process more thorough and efficient.

[0027] At the third preset temperature, the adhesive layer undergoes a cross-linking and curing reaction, which enables at least one of the substrate and backplane to be firmly bonded to the battery string, thereby completing the curing process of the substrate and forming a stable and reliable encapsulation structure. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0029] Figure 1 This is a schematic diagram of a photovoltaic module provided in an embodiment of this application;

[0030] Figure 2 This is a schematic diagram of a photovoltaic encapsulant film provided in an embodiment of this application;

[0031] Figure 3 This is a schematic flowchart of a photovoltaic module encapsulation method provided in an embodiment of this application.

[0032] Explanation of reference numerals in the attached figures:

[0033] 10. Matrix; 20. Frame;

[0034] 100. Substrate;

[0035] 200, Photovoltaic encapsulant film; 201, First encapsulant film; 202, Second encapsulant film; 210, Adhesive layer; 220, Barrier layer; 230, Support layer.

[0036] 300, battery string;

[0037] 400. Back panel.

[0038] To facilitate understanding of the embodiments of this application, the spline curves and arrows used in the reference numerals in the accompanying drawings are explained below: the components indicated by spline curves without arrows can be solid components, that is, components with solid structures; the components indicated by spline curves with arrows can be virtual components, that is, components without solid structures; in some cases, the components indicated by spline curves with arrows can also be assemblies with solid structures or virtual structures.

[0039] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0041] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In the description of the embodiments of this application, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships (if present), are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of this application 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, and therefore should not be construed as a limitation on the embodiments of this application. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Where there is no conflict, embodiments of this application and the various features thereof can be combined with each other, all of which are within the scope of protection of this application.

[0042] Figure 1 This is a schematic diagram of a photovoltaic module provided in an embodiment of this application.

[0043] like Figure 1 As shown, this application embodiment provides a photovoltaic module, including a substrate 100, a photovoltaic encapsulant film 200, a cell string 300, and a backsheet 400. The photovoltaic encapsulant film 200 may include a first encapsulant film 201 and a second encapsulant film 202, and the substrate 100, the first encapsulant film 201, the cell string 300, the second encapsulant film 202, and the backsheet 400 may be stacked sequentially.

[0044] The first adhesive film 201 is used to connect the battery string 300 to the substrate 100, and the second adhesive film 202 is used to connect the battery string 300 to the back plate 400. At least one of the substrate 100 and the back plate 400 can transmit light. At least one of the substrate 100 and the back plate 400 can also provide support.

[0045] It is understandable that the structure of the first adhesive film 201 may be consistent or inconsistent.

[0046] In some embodiments, the substrate 100, the first encapsulant film 201, the battery string 300, the second encapsulant film 202 and the backplate 400 stacked in sequence can together constitute the base 10 of the photovoltaic module. The photovoltaic module may also include a frame 20, which can be arranged circumferentially around the base 10.

[0047] Figure 2 This is a schematic diagram of a photovoltaic encapsulant film 200 provided in an embodiment of this application. In some embodiments, the photovoltaic encapsulant film 200 may include a first encapsulant film 201 and / or a second encapsulant film 202. Exemplarily, the structure of the first encapsulant film 201 and / or the second encapsulant film 202 may be consistent with that of the photovoltaic encapsulant film 200.

[0048] like Figure 2 As shown, this application embodiment provides a photovoltaic encapsulant film 200, including an adhesive layer 210, which is used to adhere at least one of the substrate 100 and the back sheet 400 to the cell string 300.

[0049] In some embodiments, at least one of the first adhesive film 201 and the second adhesive film 202 may include a barrier layer 220. The barrier layer 220 may be disposed between at least one of the substrate 100 and the back plate 400 and the battery string 300, and the barrier layer 220 is used to block moisture.

[0050] In some embodiments, at least one of the first adhesive film 201 and the second adhesive film 202 may further include a support layer 230, which may be disposed between the corresponding barrier layer 220 and the battery string 300.

[0051] This application also provides a laminator, including a main structure, a heating system, a vacuum system, a pressure system, and a control system. The main structure provides a cavity for housing photovoltaic modules. The control system is communicatively connected to the heating system, vacuum system, and pressure system. The control system can control the activation of the heating system to heat the photovoltaic modules; it can also control the activation of the vacuum system to provide a vacuum environment for the photovoltaic modules; and it can further control the activation of the pressure system to laminate the photovoltaic modules.

[0052] In some embodiments, the main structure may include at least one receiving cavity. When there are two or more receiving cavities, the functions of each receiving cavity may be the same or different. Exemplarily, some receiving cavities may be used for lamination, and other receiving cavities may be used for curing.

[0053] In some embodiments, the heating system can achieve heating through the circulation of heat transfer oil, which provides more uniform and stable temperature and high temperature control accuracy. Alternatively, in other embodiments, the heating system can also achieve heating through heating tubes or heating plates, where electric heating provides rapid temperature rise and a relatively simple structure.

[0054] In some examples, the heating system may also include a temperature sensor that can be used to detect the temperature inside the containment cavity.

[0055] In some embodiments, the vacuum system may include a vacuum pump, vacuum lines, vacuum valves, a vacuum gauge, etc. The vacuum pump may include at least one of a Roots pump and a rotary vane pump, and the vacuum gauge may be used to measure the vacuum level within the containment cavity.

[0056] In some embodiments, the pressure system can use a rubber airbag or silicone diaphragm to fill the vacuum chamber with compressed air (nitrogen), and then use a flexible medium (such as a silicone plate) to uniformly transfer the pressure to the surface of the photovoltaic module. This results in good pressure uniformity and is suitable for modules of different thicknesses.

[0057] In some embodiments, the control system may include a programmable logic controller, a microcontroller, or a computer. In some examples, the control system may also include a human-machine interface, such as a display panel.

[0058] In some embodiments, the laminator may further include a conveying system. The conveying system may employ rollers or chain conveyors to transport the photovoltaic modules to be laminated into the receiving cavity.

[0059] Currently, photovoltaic (PV) modules are power generation units formed by encapsulating strings of cells. The encapsulation process is a crucial step in PV module manufacturing, and its quality directly affects the power generation efficiency, reliability, and lifespan of the PV module.

[0060] Related technologies provide a method for encapsulating photovoltaic modules, including: sequentially laying a first encapsulant film, a cell string, a second encapsulant film, and a glass backsheet on a glass substrate to form a module to be laminated; and vacuum heating and pressing the module to be laminated at a preset temperature to cure it.

[0061] However, due to the low melting points of the first and second encapsulants, under a preset temperature environment (i.e., a high-temperature environment), the viscosity of the first and second encapsulants after melting is high. This results in poor fluidity of the first and second encapsulants, making it unable to effectively fill the tiny gaps on the surface of the battery string. Consequently, a large number of air bubbles remain between the battery string and the encapsulant. These air bubbles not only affect the appearance quality of the photovoltaic module but also cause localized overheating during long-term use, i.e., the hot spot effect. This can lead to delamination between the substrate and / or backsheet and the battery string, severely impacting the power generation efficiency and lifespan of the photovoltaic module.

[0062] Figure 3 This is a schematic flowchart of a photovoltaic module encapsulation method provided in an embodiment of this application.

[0063] In view of this, such as Figure 3As shown in the illustration, this application also provides a method for encapsulating a photovoltaic module. This method can be used to manufacture photovoltaic modules, and the structure of the photovoltaic module is described above. The photovoltaic module encapsulation method includes:

[0064] S100, a first adhesive film 201, a battery string 300, a second adhesive film 202 and a backplate 400 are sequentially deposited on a substrate 100 to form a substrate 10. At least one of the first adhesive film 201 and the second adhesive film 202 includes an adhesive layer 210, which has a first melting point.

[0065] Specifically, a first adhesive film 201, a battery string 300, a second adhesive film 202, and a backplate 400 are sequentially deposited on a substrate 100 to form a substrate 10 structure to be encapsulated. At least one of the first adhesive film 201 and the second adhesive film 202 includes an adhesive layer 210, which has a specific first melting point. The substrate 100 can be a glass substrate or other light-transmitting material, and the backplate 400 can be a glass backplate 400 or a composite backplate 400. The first adhesive film 201 is deposited on the upper surface of the substrate 100, the battery string 300 is placed on the first adhesive film 201, the second adhesive film 202 covers the upper surface of the battery string 300, and the backplate 400 serves as the outermost layer covering the second adhesive film 202, thereby forming a complete layered structure. The adhesive layer 210 enables the adhesive film to have controllable melting characteristics, laying the foundation for subsequent heat treatment.

[0066] In some embodiments, the substrate 100 may be made of tempered glass, ultra-clear glass, or low-iron glass, or it may be made of a transparent polymer material, such as polycarbonate or polymethyl methacrylate, to meet the requirements of light transmittance and mechanical strength for different application scenarios. For example, the substrate 100 may be made of ultra-clear tempered glass, whose coefficient of thermal expansion can be (8.0~9.5) × / ℃ (within the range of 20℃~300℃).

[0067] In some embodiments, the battery string 300 may include a plurality of battery cells electrically connected together. Exemplarily, the battery cells may be monocrystalline silicon cells or polycrystalline silicon cells, etc. The coefficient of thermal expansion of a monocrystalline silicon cell is (2.5–3.0) × At / ℃, the coefficient of thermal expansion of polycrystalline silicon solar cells is (3.8~4.2)× / ℃.

[0068] In some embodiments, the back panel 400 may also be a glass back panel 400.

[0069] In some embodiments, the first adhesive film 201 and the second adhesive film 202 may use the same material and structure, or they may use different materials and structures, for example, the adhesive layer 210 of the two films may have different thicknesses, in order to meet different encapsulation requirements.

[0070] S200: Heat the substrate 10 at a first preset temperature and evacuate the area around the substrate 10 so that the adhesive layer 210 melts and removes the air bubbles on the surface of the battery string 300. The first preset temperature is greater than or equal to the first melting point.

[0071] The first preset temperature is set to be greater than or equal to the first melting point of the adhesive layer 210 to ensure that the adhesive layer 210 can be fully melted. Under this temperature condition, the adhesive layer 210 is in a low viscosity state and has good fluidity, which can quickly wet the surface of the battery string 300 with the assistance of a vacuum environment. Since the first preset temperature is relatively low, the flow of the adhesive layer 210 is relatively gentle, and it can gradually penetrate into the tiny gaps and depressions on the surface of the battery string 300, expelling the gas therein. The establishment of a vacuum environment provides a driving force for the expulsion of bubbles, allowing the bubbles to detach smoothly from the substrate 10, thereby achieving the initial wetting and venting of the battery string 300.

[0072] In some embodiments, the substrate 10 may be placed in a laminator.

[0073] In some embodiments, a vacuum system of the laminator can be used for evacuation. In some examples, a mechanical pump, molecular pump, or the like can be used to evacuate the space in the laminator used to house the substrate 10. In some examples, the vacuum level can be less than -0.095 MPa to ensure effective venting.

[0074] In some embodiments, the first preset temperature can be set in the range of 65°C to 75°C. For example, the first preset temperature can be set using the heating system of a laminator.

[0075] S300, the substrate 10 is heated at a second preset temperature and pressed with a preset pressure so that the adhesive layer 210 fills the edge of the battery string 300, and the second preset temperature is greater than the first preset temperature.

[0076] The second preset temperature is higher than the first preset temperature. At this temperature, the viscosity of the adhesive layer 210 increases moderately, resulting in better filling capacity. By applying a preset pressure, the adhesive layer 210 can be pressed into the tiny gaps at the edge of the battery string 300, achieving coverage of the surrounding area of ​​the battery string 300. The application of pressure causes the adhesive layer 210 to deform and flow within the confined space, ensuring that there are no gaps or only small gaps between the battery string 300 and the adhesive film.

[0077] Furthermore, under pressure, residual air bubbles that were not completely removed during the pre-impregnation stage are further squeezed and expelled, improving the thoroughness of venting. The entire lamination process is still carried out in a vacuum environment to prevent external air from entering the matrix 10.

[0078] In some embodiments, the second preset temperature can be set in the range of 110°C to 120°C. For example, the second preset temperature can be set using the heating system of the laminator.

[0079] In some embodiments, the preset pressure can be 0.3 Bar to 0.5 Bar to ensure that the adhesive layer 210 fully fills the edges of the battery string 300 and removes residual air bubbles. In some examples, a uniform pressure can be applied to ensure that the adhesive layer 210 is uniformly filled. In some examples, the preset pressure can be set and applied using the pressure system of a laminator.

[0080] S400, the substrate 10 is heated at a third preset temperature to crosslink and cure the adhesive layer 210, and at least one of the substrate 100 and the back plate 400 is bonded to the battery string 300, wherein the third preset temperature is greater than the second preset temperature.

[0081] The third preset temperature is higher than the second preset temperature. At this temperature, the molecular chains inside the adhesive layer 210 undergo a cross-linking reaction, forming a three-dimensional network structure, transforming from a liquid or softened state to a solid state. The cross-linked and cured adhesive layer 210 possesses excellent mechanical strength and adhesive properties, enabling it to firmly bond the substrate 100, the cell string 300, and the backsheet 400 into a single unit. The curing process ensures that the entire substrate 10 forms a stable encapsulation structure, guaranteeing that the layers of the photovoltaic module will not separate or shift during subsequent use.

[0082] In some embodiments, the third preset temperature can be set in the range of 140°C to 150°C. For example, the third preset temperature can be set using the heating system of the laminator.

[0083] In some embodiments, a temperature transition stage can be provided between each heating stage, employing a gradient heating method to avoid thermal shock to the substrate 10 caused by sudden temperature changes. For example, the heating rate can be controlled between 2°C / min and 10°C / min.

[0084] Since the first preset temperature is greater than or equal to the first melting point of the adhesive layer 210, the adhesive layer 210 can be fully melted at this temperature. Since the first preset temperature is lower than the second preset temperature, that is, lower than the lamination temperature of the substrate 10, the present application embodiment melts the adhesive layer 210 at a lower temperature before laminating the substrate 10, thereby achieving pre-wetting of the battery string 300.

[0085] Specifically, when the adhesive layer 210 melts at the first preset temperature, its viscosity is low and its fluidity is better than that at the lamination temperature. This low viscosity characteristic allows the adhesive layer 210 to quickly wet the surface of the cell string 300 with the assistance of a vacuum environment and quickly fill the tiny gaps and depressions on the surface of the cell string 300. This efficiently removes most of the air bubbles from the surface of the cell string 300, avoiding the problem of too many air bubbles remaining on the surface of the cell string 300. As a result, the appearance quality of the photovoltaic module is improved, and it is not easy to generate local overheating phenomenon, i.e. hot spot effect, during long-term use. Therefore, it is not easy to cause delamination problem between the substrate 100 and / or the back sheet 400 and the cell string 300.

[0086] Under the second preset temperature condition, the viscosity of the adhesive layer 210 is relatively high. At this time, it is convenient to press the substrate 10 under preset pressure in a vacuum environment, so that the adhesive layer 210 can effectively fill the edge area of ​​the battery string 300, ensuring good lamination effect. At the same time, it can further remove residual air bubbles that were not completely removed in the pre-wetting stage. This realizes the process of removing air bubbles in two stages, making the degassing process more thorough and efficient.

[0087] At a third preset temperature, the adhesive layer 210 undergoes a cross-linking and curing reaction, which enables at least one of the substrate 100 and the backplate 400 to be firmly bonded to the battery string 300, thereby completing the curing process of the substrate 10 and forming a stable and reliable encapsulation structure.

[0088] Understandably, the edge region of the battery string 300 may also include solder strips electrically connected to the battery string 300, which can be used to transmit current. The adhesive layer 210 may also fill the edges of the solder strips.

[0089] In some possible implementations, the adhesive layer 210 is a modified polyolefin elastomer (POE) layer with a melting point of 60°C to 80°C, for example, 60°C, 70°C or 80°C.

[0090] In this embodiment, the adhesive layer 210 is a modified polyolefin elastomer layer. The modified polyolefin elastomer layer is a material obtained by modifying a standard polyolefin elastomer through the addition of modifiers or adjustment of polymerization process parameters. This modification process can adjust the molecular structure and crystallinity of the material, thereby lowering the melting point of the adhesive layer 210 to the range of 60°C to 80°C.

[0091] In some examples, the modification process may include grafting modification, blending modification, or the addition of additives that lower the melting point, so that the modified polyolefin elastomer layer can reach a molten state at a lower temperature.

[0092] In this embodiment, the melting point of the adhesive layer 210 is controlled within a temperature range of 60°C to 80°C. This temperature range is designed to fully consider the actual needs of the pre-impregnation process. 60°C is set as the lower limit temperature to ensure that the adhesive layer 210 can melt under reasonable heating conditions, while 80°C is set as the upper limit temperature to ensure sufficient melting point difference between the adhesive layer 210 and other functional layers, thereby achieving a staged melting process.

[0093] In some possible implementations, at least one of the first adhesive film 201 and the second adhesive film 202 further includes a barrier layer 220 disposed between the adhesive layer 210 and the battery string 300. The barrier layer 220 is used to block moisture. The barrier layer 220 has a second melting point, which is greater than a first preset temperature, and the second preset temperature is greater than the second melting point.

[0094] In this embodiment, at least one of the first adhesive film 201 and the second adhesive film 202 adopts a multilayer composite structure, including an adhesive layer 210 and a barrier layer 220. The barrier layer 220 is disposed between the adhesive layer 210 and the battery string 300, forming an intermediate functional layer of the adhesive film.

[0095] In the actual use environment of photovoltaic modules, moisture from the external environment may penetrate into the interior through the substrate 100 or backsheet 400. If moisture comes into contact with the cell string 300, it can cause oxidation and corrosion of the electrodes, affecting the power generation performance and lifespan of the cell string 300. By setting a barrier layer 220 between the adhesive layer 210 and the cell string 300, a moisture barrier can be formed between the adhesive layer 210 and the cell string 300, effectively preventing moisture from continuing to penetrate into the cell string 300, thereby protecting the cell string 300 from moisture corrosion.

[0096] The barrier layer 220 has a second melting point, which is higher than the first preset temperature. This means that when the substrate 10 is heated at the first preset temperature, the adhesive layer 210 has reached or exceeded its first melting point and begins to melt, but the barrier layer 220, due to its higher second melting point, remains solid and does not melt. At this time, although the adhesive layer 210 melts and has good fluidity, the barrier layer 220 remains solid, which can support and restrict the adhesive layer 210, preventing excessive diffusion of the adhesive layer 210 after melting and causing the overall film to shift position, thus ensuring that the relative positional relationship between the film and the battery string 300 remains stable.

[0097] Simultaneously, the second preset temperature is higher than the second melting point. This indicates that when the heating temperature of the substrate 10 rises to the second preset temperature, the temperature of the barrier layer 220 will also exceed its second melting point, at which point the barrier layer 220 begins to melt. After the barrier layer 220 melts, its viscosity decreases and its fluidity increases. Under the action of the preset pressure, the barrier layer 220 can flow and fill the edge area of ​​the battery string 300 together with the adhesive layer 210, so that the barrier layer 220 can also fully fill the tiny gaps and irregular areas at the edge of the battery string 300, achieving a more complete and dense encapsulation effect.

[0098] Therefore, it can be seen that during the melting and flow process, the barrier layer 220 can also help to remove some of the bubbles remaining on the surface or edge of the battery string 300. In combination with the venting effect of the adhesive layer 210 in the pre-wetting stage, a two-stage and two-material synergistic bubble removal method is realized, which makes the bubble removal more thorough and efficient, further improving the appearance quality and reliability of photovoltaic modules, and reducing the hot spot effect and delamination risk caused by bubble residue.

[0099] In some possible implementations, the barrier layer 220 is an ethylene-vinyl alcohol copolymer (EVOH), an antioxidant polymer layer, a light stabilizer polymer layer, or a coupling agent polymer layer, and the melting point of the barrier layer 220 is 110°C to 140°C, for example, 110°C, 120°C, 130°C, or 140°C.

[0100] By using an ethylene-vinyl alcohol copolymer layer, an antioxidant polymer layer, a light stabilizer polymer layer, or a coupling agent polymer layer as a barrier layer 220, these materials all have a dense molecular structure or special functional groups, which can effectively prevent water vapor and oxygen from penetrating into the direction of the battery string 300, thereby avoiding electrochemical corrosion or performance degradation of the battery string 300 due to water vapor erosion, thus ensuring the power generation efficiency and reliability of photovoltaic modules during long-term outdoor use.

[0101] Meanwhile, the melting point of the barrier layer 220 is set to a specific range of 110°C to 140°C, so that the barrier layer 220 remains solid at the first preset temperature. During the pre-wetting stage, this prevents the adhesive film from excessively spreading or shifting in position due to the melting of the adhesive layer 210, thus ensuring the accuracy of the relative position of the adhesive film and the battery string 300.

[0102] At the second preset temperature, the barrier layer 220 completely melts and has suitable fluidity, which can fully fill the tiny gaps and edge areas on the surface of the battery string 300 under the action of preset pressure, realizing a dense laminated structure, further eliminating residual air bubbles and improving the lamination quality.

[0103] Furthermore, the coefficient of thermal expansion of the aforementioned barrier layer 220 material is typically smaller than that of conventional ethylene-vinyl acetate copolymer films (e.g., (150–200) × 10⁻⁶). (°C) or the coefficient of thermal expansion of a standard polyolefin elastomer film (e.g., (120–150) × 100°C) / ℃), which makes the average coefficient of thermal expansion of the first adhesive film 201 and the second adhesive film 202 (for example, (110~130)×) The coefficient of thermal expansion (C / ℃) is reduced. When photovoltaic modules experience diurnal temperature variations or seasonal temperature fluctuations, a smaller coefficient of thermal expansion means less thermal expansion and contraction of the encapsulant film, thereby reducing the thermal stress at the bonding interfaces between the encapsulant film and the substrate 100, and between the encapsulant film and the cell string 300. This reduction in thermal stress directly reduces the risk of interface separation or delamination, thus improving the long-term reliability and lifespan of the photovoltaic modules and ensuring stable operation of the modules under various environmental conditions.

[0104] In some embodiments, the barrier layer 220 can adopt a multi-layer composite structure, such as a composite of an ethylene-vinyl alcohol copolymer layer and an antioxidant polymer layer, or a composite of a light stabilizer polymer layer and a coupling agent polymer layer. By superimposing different functional layers, multiple functions such as water vapor barrier, anti-oxidation, light stabilization and interface enhancement can be achieved simultaneously, further improving the overall performance of the photovoltaic module.

[0105] In some embodiments, inorganic fillers, such as nano-silica, nano-alumina, or layered silicates, can be added to the barrier layer 220. These inorganic fillers can further improve the water vapor barrier performance and mechanical strength of the barrier layer 220, and can also adjust the melting point and thermal expansion coefficient of the barrier layer 220 to better match the requirements of the packaging process.

[0106] In some possible implementations, at least one of the first adhesive film 201 and the second adhesive film 202 further includes a support layer 230, which is disposed between the barrier layer 220 and the battery string 300. The support layer 230 has a third melting point, which is greater than a first preset temperature and a second preset temperature is greater than the third melting point.

[0107] Specifically, the support layer 230 is located between the barrier layer 220 and the battery string 300, forming the intermediate functional layer of the adhesive film. The main function of the support layer 230 is to provide the necessary mechanical strength for the entire adhesive film, making it less prone to tearing or deformation during laying and transportation. At the same time, the support layer 230 also has good insulation properties, which can effectively isolate the positive and negative electrodes of the battery string 300 and prevent leakage.

[0108] The support layer 230 has a third melting point, which is set according to a specific temperature gradient. Specifically, the third melting point is higher than a first preset temperature, meaning that during the pre-wetting stage of heating the substrate 10 at the first preset temperature, the support layer 230 remains in a solid state and does not melt. This design ensures that during the process of the adhesive layer 210 melting and removing air bubbles from the surface of the battery string 300, the support layer 230 can maintain the overall structural stability of the adhesive film, preventing excessive diffusion or displacement of the adhesive film due to the melting of the adhesive layer 210.

[0109] Meanwhile, the second preset temperature is higher than the third melting point, indicating that when the heating temperature rises to the second preset temperature for lamination, the support layer 230 will melt. At this time, under the action of the preset pressure, the already melted support layer 230 can work synergistically with the adhesive layer 210 and the barrier layer 220, which are also in a molten state, to fill the edge areas of the battery string 300 and the tiny gaps between the battery cells. This multi-layer synergistic melting method allows the adhesive film to more fully cover all surfaces of the battery string 300, forming a uniform and dense encapsulation layer.

[0110] Thus, by using the initial venting in the pre-impregnation stage and the deep venting in the lamination stage, a two-stage degassing process is formed. This staged venting mechanism makes the removal of bubbles more thorough. Compared with the traditional single-stage venting process, it can reduce the residual bubble rate in the encapsulated module to a lower level, thereby effectively avoiding the hot spot effect caused by residual bubbles and the risk of delamination during long-term use, and improving the power generation efficiency and service life of photovoltaic modules.

[0111] In some possible implementations, the support layer 230 is a polyolefin elastomer (POE) layer or a polyethylene (PE) layer, and the melting point of the support layer 230 is 90°C to 140°C, for example, 90°C, 100°C, 110°C, 120°C or 140°C.

[0112] In this embodiment, since the melting point of the support layer 230 is higher than the first preset temperature, the support layer 230 can remain solid and not melt when the pre-impregnation treatment is performed at the first preset temperature. At this time, the support layer 230 and the barrier layer 220 work together to provide dual structural stability for the adhesive film, effectively preventing the adhesive film from excessively spreading or shifting in position when the adhesive layer 210 melts and flows, thereby ensuring the positional accuracy of the battery string 300 in the pre-impregnation stage.

[0113] Meanwhile, since the melting point of the support layer 230 is lower than the second preset temperature, the support layer 230 can be fully melted when laminating at the second preset temperature. The molten material has good fluidity and filling performance under the preset pressure, which can effectively fill the tiny gaps at the edge of the battery string 300 and further remove residual bubbles that were not completely removed in the pre-wetting stage. This achieves a staged, multi-layered bubble removal mechanism, making bubble removal more thorough and efficient.

[0114] Furthermore, the polyolefin elastomer or polyethylene layer itself has a low coefficient of thermal expansion. By using these materials as the support layer 230, the average coefficient of thermal expansion of the multilayer film structure comprising the adhesive layer 210, the barrier layer 220, and the support layer 230 is reduced to, for example, (110–130) × 10⁻⁶. ⁻6 The coefficient of thermal expansion (°C) is lower than that of conventional single-material films (such as ethylene-vinyl acetate copolymer films or standard polyolefin elastomer films). This lower coefficient of thermal expansion means that when photovoltaic modules undergo temperature cycling, less thermal stress accumulates between the film and the substrate 100 and between the film and the cell string 300. This reduces the probability that the bonding interface will be damaged or separated due to thermal expansion and contraction, and improves the long-term reliability and service life of photovoltaic modules.

[0115] In some embodiments, the support layer 230 may be a low-density polyethylene (LDPE) layer with a density of 0.910 g / cm³ to 0.940 g / cm³ and a melting point of 105°C to 115°C.

[0116] Alternatively, in other embodiments, the support layer 230 may also be a linear low-density polyethylene (LLDPE) layer with a density of 0.915 g / cm³ to 0.935 g / cm³ and a melting point of 120°C to 125°C.

[0117] Alternatively, in some other embodiments, the support layer 230 may also be a high-density polyethylene (HDPE) layer with a density of 0.941 g / cm³ to 0.965 g / cm³ and a melting point of 130°C to 137°C.

[0118] In some possible implementations, prior to step S300, the photovoltaic module encapsulation method further includes:

[0119] S500, detects the vacuum level on the 10th side of the substrate.

[0120] During the heating of the substrate 10 at the first preset temperature, the vacuum level in the surrounding area of ​​the substrate 10 is monitored in real time by the vacuum system of the laminator. This vacuum system continuously monitors the pressure changes within the chamber during the vacuuming process and feeds back the detected vacuum level values ​​to the laminator's control system. This monitoring process is conducted throughout the entire heating stage at the first preset temperature, ensuring that the accurate state of the vacuum environment can be obtained in a timely manner.

[0121] S600. If the vacuum level reaches the preset value, the temperature of the heating substrate 10 is increased from the first preset temperature to the second preset temperature.

[0122] After receiving the feedback value from the vacuum system, the laminator's control system compares this value with a preset value. This preset value is a vacuum standard determined according to the lamination process requirements; typically, a high vacuum level is needed to meet the quality requirements of subsequent lamination processes. The control system continuously compares the real-time vacuum level with the preset value to determine whether the vacuuming process is complete.

[0123] Once the control system determines that the vacuum level around the substrate 10 has reached a preset value, it issues a heating command to control the laminator's heating system to gradually raise the temperature of the substrate 10 from a first preset temperature to a second preset temperature. This heating process is carried out under the premise that the vacuum environment meets the standards, ensuring that the substrate 10 is under ideal process conditions when entering the lamination stage.

[0124] In some embodiments, the preset value may be less than -0.095 MPa.

[0125] In some embodiments, the heating rate from the first preset temperature to the second preset temperature can be set to 1°C / min to 4°C / min to achieve a smooth temperature transition. Alternatively, a segmented heating method can be adopted, first heating at a faster rate to an intermediate temperature, and then heating at a slower rate to the second preset temperature, thereby balancing production efficiency and process stability.

[0126] In some embodiments, if the vacuum level is detected to fail to reach the preset value within a preset time, the control system may issue an alarm signal and suspend the process flow so that the operator can check whether there is a leak or other fault in the vacuum system and ensure that the laminator is running normally before continuing the subsequent process.

[0127] Because the lamination process has strict requirements for the vacuum environment, if lamination is carried out when the vacuum level is not up to standard, the gas remaining inside the substrate 10 will form bubble defects under high temperature and high pressure conditions, thus affecting the encapsulation quality of the photovoltaic module.

[0128] By checking the vacuum level before heating to the second preset temperature, it can be ensured that the gas around the substrate 10 has been fully extracted, allowing the adhesive layer 210 to better wet the surface of the battery string 300 during the melting process and reducing the possibility of residual bubbles. Heating is only carried out after the vacuum level reaches the preset value. At this time, the gas pressure in the chamber has dropped to the standard level required for the lamination process. When the adhesive layer 210, barrier layer 220, and support layer 230 melt at the second preset temperature and fill the edge of the battery string 300 under the action of the preset pressure, no new bubbles will be generated due to residual gas in the environment, thus ensuring the stability and consistency of the lamination effect.

[0129] This process control method, which confirms the vacuum environment before lamination, effectively avoids encapsulation defects caused by insufficient vacuum, improves the yield and reliability of photovoltaic modules, and makes the adhesion between the substrate 100 and backsheet 400 and the cell string 300 more solid, making it less prone to delamination during long-term use.

[0130] In some possible implementations, after step S400, the photovoltaic module encapsulation method further includes:

[0131] S700, the temperature of the heated substrate 10 is reduced from the third preset temperature to the first preset temperature at the first cooling rate.

[0132] After the adhesive layer 210 has completed cross-linking and curing, and the substrate 100, backsheet 400, and battery string 300 are firmly bonded, the heating system of the laminator can be controlled to cool the substrate 10 at a first cooling rate. Specifically, the temperature of the substrate 10 is gradually reduced from a third preset temperature to a first preset temperature. During this cooling stage, due to the relatively slow cooling rate, the temperature change of each layer of material inside the substrate 10 is relatively gradual, and the temperature gradient between each layer is relatively small. This slow cooling method allows the substrate 100, adhesive film layer, battery string 300, and backsheet 400 to shrink synchronously, avoiding large shrinkage differences between different material layers due to a sudden drop in temperature.

[0133] S800, the temperature of the heated substrate 10 is reduced from the first preset temperature to room temperature at a second cooling rate, wherein the second cooling rate is greater than the first cooling rate.

[0134] Once the temperature of the substrate 10 drops to the first preset temperature, the cooling rate is switched to the second cooling rate to continue cooling the substrate 10 until its temperature reaches room temperature. The second cooling rate used here is significantly greater than the first cooling rate, achieving a faster cooling process. Since the main thermal stress accumulated during the encapsulation process has been fully released through slow cooling in the previous stage, the materials within the substrate 10 have reached a relatively stable state. Therefore, using a faster cooling rate at this point will not cause significant thermal shock to the structure of the substrate 10.

[0135] Therefore, it can be seen that in the first cooling stage, due to the slower initial cooling rate, the substrate 10 can maintain relatively synchronized temperature changes as it cools from the third preset temperature to the first preset temperature, avoiding stress concentration at the material interfaces caused by excessive temperature gradients. Especially for the thin-film battery string 300, which is thinner and has relatively lower mechanical strength, it can gradually adapt to the dimensional shrinkage caused by temperature changes during the slow cooling process, preventing excessive thermal stress concentration inside the battery cell due to sudden temperature changes. This slow cooling method effectively avoids the huge thermal shock caused by rapid cooling in traditional processes, allowing the thermal stress accumulated during the encapsulation process to be fully released, thereby reducing the risk of microcracks or breakage in the thin-film battery string 300 and effectively reducing the fragmentation rate.

[0136] In the second cooling stage, although a larger cooling rate was used, the substrate 10 temperature had already dropped to the first preset temperature, and the main thermal stress inside the material had been released in the previous stage, establishing a relatively stable bonding state between the layers. Under these conditions, even with a faster cooling rate, there would be no significant negative impact on the substrate 10 structure. Furthermore, a faster cooling rate can shorten the overall packaging cycle time, improve production efficiency, and reduce the energy cost per unit product.

[0137] In summary, by implementing a gradient cooling strategy, the system can ensure the full release of internal stress and protect the 300-cell thin-film battery from microcracks or breakage, while also improving production efficiency, thus achieving a balanced optimization of product quality and production efficiency.

[0138] In some embodiments, a constant temperature holding stage may be added between the first cooling stage and the second cooling stage, maintaining the temperature at a first preset temperature for a preset duration to further ensure the full release of thermal stress.

[0139] In some possible implementations, the first cooling rate is 1℃ / min to 4℃ / min, for example, 1℃ / min, 2℃ / min, 3℃ / min or 4℃ / min; the second cooling rate is 5℃ / min to 10℃ / min, for example, 5℃ / min, 7℃ / min, 9℃ / min or 10℃ / min.

[0140] During the first cooling stage, due to the relatively slow cooling rate of 1℃ / min to 4℃ / min, as the substrate 10 cools from the third preset temperature to the first preset temperature, the molecular chains of the materials in each functional layer, such as the adhesive layer 210, the barrier layer 220, and the support layer 230, can be fully relaxed. The dimensional changes of each layer due to thermal expansion and contraction are relatively synchronized, thereby gradually releasing the shear stress and tensile stress at the material interfaces. Especially for the thin-film battery string 300, which is thin and brittle, it is prone to microcracks due to internal stress concentration when the temperature changes rapidly. By controlling the first cooling rate within the range of 1℃ / min to 4℃ / min, it can be ensured that the battery string 300 is always in a low stress state during the cooling process, effectively avoiding the generation of microcracks.

[0141] Meanwhile, due to the different coefficients of thermal expansion of each layer of material, the thermal mismatch stress between the substrate 100, the adhesive film and the backplate 400 can be gradually dissipated through the viscoelastic deformation of the materials during the slow cooling process, and stress concentration points will not be formed at the interface, thereby reducing the risk of battery string 300 breaking.

[0142] In the second cooling stage, when the temperature of the substrate 10 drops from the first preset temperature to room temperature, a relatively fast cooling rate of 5℃ / min to 10℃ / min is adopted. At this time, the main thermal stress inside the substrate 10 has been fully released in the first cooling stage, the adhesive layer 210 has been completely cured and formed a stable adhesive structure with the battery string 300, and the interfacial bonding strength between the materials has reached the design requirements.

[0143] In this state, the overall structure of the substrate 10 has become stable, and its sensitivity to temperature changes has been greatly reduced. Therefore, it can withstand faster cooling rates without adversely affecting product quality. By increasing the second cooling rate to 5°C / min to 10°C / min, the time required to cool from the first preset temperature to room temperature can be shortened, thereby improving the overall production efficiency of the packaging process and reducing energy consumption and time costs per unit product.

[0144] By employing a gradient cooling approach—first releasing stress at a slower initial cooling rate, then increasing efficiency at a faster second cooling rate—a balance between stress control and production efficiency is achieved. This segmented cooling strategy avoids the thermal shock effect caused by rapid cooling in traditional processes, ensuring that the substrate 10 remains under controllable stress throughout the cooling process. This effectively reduces the breakage rate of the thin-film cell string 300, improving the yield and reliability of photovoltaic modules.

[0145] It should be understood that the embodiments of this application are not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for encapsulating a photovoltaic module, characterized in that, include: A first adhesive film, a battery string, a second adhesive film, and a backplate are sequentially deposited on a substrate to form a matrix. At least one of the first adhesive film and the second adhesive film includes an adhesive layer, and the adhesive layer has a first melting point. The substrate is heated to a first preset temperature, and a vacuum is drawn in the area around the substrate to melt the adhesive layer and remove air bubbles from the surface of the battery string. The first preset temperature is greater than or equal to the first melting point. The substrate is heated at a second preset temperature and pressed with a preset pressure so that the adhesive layer fills the edge of the battery string. The second preset temperature is greater than the first preset temperature. The substrate is heated at a third preset temperature to crosslink and cure the adhesive layer, and to bond at least one of the substrate and the backplate to the battery string, wherein the third preset temperature is greater than the second preset temperature.

2. The photovoltaic module encapsulation method according to claim 1, characterized in that, The adhesive layer is a modified polyolefin elastomer layer, and the melting point of the adhesive layer is 60°C to 80°C.

3. The photovoltaic module encapsulation method according to claim 1, characterized in that, At least one of the first adhesive film and the second adhesive film further includes a barrier layer disposed between the adhesive layer and the battery string. The barrier layer is used to block moisture. The barrier layer has a second melting point, which is greater than the first preset temperature, and the second preset temperature is greater than the second melting point.

4. The photovoltaic module encapsulation method according to claim 3, characterized in that, The barrier layer is an ethylene-vinyl alcohol copolymer layer, an antioxidant polymer layer, a light stabilizer polymer layer, or a coupling agent polymer layer, and the melting point of the barrier layer is 110°C to 140°C.

5. The photovoltaic module encapsulation method according to claim 3, characterized in that, At least one of the first adhesive film and the second adhesive film further includes a support layer, the support layer being disposed between the barrier layer and the battery string, the support layer having a third melting point, the third melting point being greater than the first preset temperature, and the second preset temperature being greater than the third melting point.

6. The photovoltaic module encapsulation method according to claim 5, characterized in that, The support layer is a polyolefin elastomer layer or a polyethylene layer, and the melting point of the support layer is 90°C to 140°C.

7. The photovoltaic module encapsulation method according to any one of claims 1-6, characterized in that, Before the step of heating the substrate at a second preset temperature in a vacuum environment and pressing the substrate with a preset pressure to make the adhesive layer fill the edges of the battery string, the method further includes: Detect the vacuum level around the substrate; If the vacuum level reaches a preset value, the temperature of the heated substrate will be increased from the first preset temperature to the second preset temperature.

8. The photovoltaic module encapsulation method according to any one of claims 1-6, characterized in that, After the step of heating the substrate at a third preset temperature to crosslink and cure the adhesive layer, and bonding at least one of the substrate and the backplate to the battery string, the method further includes: The temperature of the heated substrate is reduced from the third preset temperature to the first preset temperature at a first cooling rate. The temperature of the heated substrate is reduced from the first preset temperature to room temperature at a second cooling rate, wherein the second cooling rate is greater than the first cooling rate.

9. The photovoltaic module encapsulation method according to claim 8, characterized in that, The first cooling rate is 1°C / min to 4°C / min; the second cooling rate is 5°C / min to 10°C / min.

10. A photovoltaic module, characterized in that, The photovoltaic module is prepared by the encapsulation method according to any one of claims 1-9.

Images