Composite solder strip, photovoltaic module and photovoltaic system

Abstract

This utility model relates to the field of photovoltaic technology, specifically providing a composite solder ribbon, a photovoltaic module, and a photovoltaic system. It aims to solve the problem of poor solder joints and fatigue fracture in existing photovoltaic modules during thermal cycling due to the large difference in thermal expansion coefficients between the solder ribbon and the encapsulant film. The composite solder ribbon of this application is used to connect two adjacent cells of a photovoltaic module. The photovoltaic module includes a front panel, a first encapsulant film, multiple cells, a second encapsulant film, and a back panel, stacked sequentially. The composite solder ribbon includes a solder ribbon body and a buffer layer. The thermal expansion coefficient of the buffer layer is between that of the solder ribbon body and the encapsulant film. The buffer layer is at least disposed between the solder ribbon body and the first and / or second encapsulant films. This application can reduce the interfacial stress caused by the large difference in thermal expansion coefficients between the solder ribbon and the encapsulant film through the buffer layer, thereby reducing the problem of poor solder joints and fatigue fracture in photovoltaic modules during cycling.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic technology, specifically providing a composite welding strip, a photovoltaic module, and a photovoltaic system. Background Technology

[0002] Photovoltaic power generation is a technology that converts solar energy into electrical energy. Its core component is the solar panel, also known as a photovoltaic module. With the rapid development of photovoltaic technology, photovoltaic modules are widely used in rooftop power stations, ground-mounted power stations, and distributed energy systems.

[0003] The main structure of a photovoltaic module includes the panel (i.e., glass), EVA film, solar cells, and backsheet. The front of the photovoltaic module is covered with a layer of tempered glass, which provides some protection for the photovoltaic cells encapsulated inside the module.

[0004] Solder ribbons are used to connect two adjacent cells in a photovoltaic module. The solder ribbons are welded to the cells to form solder joints. After the photovoltaic module is assembled, the solder ribbons come into contact with the encapsulant film. However, due to the large difference in the coefficient of thermal expansion between the solder ribbons and the encapsulant film, the photovoltaic module is prone to problems such as poor solder joints and fatigue fractures during hot and cold cycles, which affects the service life of the photovoltaic module. Utility Model Content

[0005] The present invention aims to solve the above-mentioned technical problems to at least a certain extent, that is, to at least a certain extent solve the problem that existing photovoltaic modules are prone to poor solder joints and fatigue fractures during hot and cold cycles due to the large difference in the coefficient of thermal expansion between the solder strip and the adhesive film.

[0006] In a first aspect, the present invention provides a composite welding ribbon for connecting two adjacent solar cells of a photovoltaic module, the photovoltaic module comprising a front panel, a first encapsulant film, a plurality of solar cells, a second encapsulant film, and a back panel stacked sequentially, characterized in that the composite welding ribbon comprises a welding ribbon body and a buffer layer disposed on the welding ribbon body, the coefficient of thermal expansion of the buffer layer being between the coefficient of thermal expansion of the welding ribbon body and the coefficient of thermal expansion of the encapsulant film, wherein the buffer layer is disposed at least between the welding ribbon body and the first encapsulant film and / or the second encapsulant film.

[0007] In the preferred embodiment of the above-mentioned composite welding strip, the coefficient of thermal expansion of the buffer layer is in the range of 150-200ppm / ℃; and / or, the modulus of the buffer layer is in the range of 10-100MPa.

[0008] In the preferred embodiment of the above-mentioned composite welding strip, the buffer layer includes one or any combination of silicone rubber, natural rubber, styrene-butadiene rubber, cis-butadiene rubber, and ethylene propylene diene monomer (EPDM) rubber.

[0009] In the preferred embodiment of the above-mentioned composite welding strip, the buffer layer extends along the length direction of the welding strip body and the length of the buffer layer is less than the length of the welding strip body.

[0010] In the preferred embodiment of the composite welding strip described above, multiple welding points are formed between the welding strip body and each of the battery cells, and the buffer layer is disposed in a local area of ​​the welding strip body and can cover the welding points.

[0011] In the preferred embodiment of the composite solder strip described above, the buffer layer is disposed on the solder strip body within the area formed by at least two adjacent solder joints near the edge of the battery cell.

[0012] In the preferred embodiment of the above-mentioned composite welding strip, the composite welding strip further includes an adhesive layer, which is disposed between the welding strip body and the buffer layer and is used to bond the buffer layer to the welding strip body; or, the buffer layer is connected to the welding strip body through a vulcanized adhesive layer.

[0013] In the preferred embodiment of the above-mentioned composite solder strip, the surface of the buffer layer on the side away from the solder strip body is wavy.

[0014] In the preferred embodiment of the above-mentioned composite welding strip, the welding strip body has a welding surface for welding with the battery cell, wherein: the buffer layer is at least disposed on the surface of the welding strip body away from the welding surface; and / or, a receiving groove adapted to the welding strip body is formed on the inner side of the buffer layer, and when assembled, the welding strip body is located in the receiving groove and the welding surface of the welding strip body is exposed from the receiving groove.

[0015] In the preferred embodiment of the above-mentioned composite solder strip, the thermal conductivity of the ends of the composite solder strip is greater than that of the middle part of the composite solder strip; and / or, the electrical conductivity of the ends of the composite solder strip is greater than that of the middle part of the composite solder strip; and / or, the adhesiveness of the ends of the composite solder strip is less than that of the middle part of the composite solder strip.

[0016] In a second aspect, the present invention also provides a photovoltaic module, the photovoltaic module comprising a front panel, a first encapsulant film, a plurality of solar cells, a second encapsulant film, a back panel, and a composite welding strip as described in any one of the first aspects, wherein the composite welding strip is used to connect two adjacent solar cells and the composite welding strip is disposed between the solar cells and the first encapsulant film and / or the second encapsulant film.

[0017] In a third aspect, the present invention also provides a photovoltaic system, the photovoltaic system comprising the photovoltaic module described in any one of the second aspects.

[0018] When the above-mentioned preferred technical solution is adopted, by setting the composite solder strip to include a solder strip body and a buffer layer disposed on the solder strip body, and setting the thermal expansion coefficient of the buffer layer to be between that of the solder strip and the encapsulant film, the interface stress caused by the large difference in thermal expansion coefficient between the solder strip and the encapsulant film can be reduced by the buffer layer. This can prevent the photovoltaic module from experiencing poor solder joints and fatigue fractures due to the large difference in thermal expansion coefficient between the solder strip and the encapsulant film during hot and cold cycles.

[0019] Furthermore, by setting the length of the buffer layer to be less than the length of the solder strip body, it is possible to avoid setting the buffer layer along the entire length of the solder strip, thereby reducing the impact of the buffer layer on the light transmittance of the solder strip and improving the performance of the photovoltaic module.

[0020] Furthermore, by setting the buffer layer in a local area of ​​the solder strip body and covering the solder joint, on the one hand, the coverage area of ​​the buffer layer on the solder strip body can be minimized, avoiding the impact on the light transmittance of the solder strip body due to the setting of the buffer layer. On the other hand, the buffer layer can be set at the solder joint position, reducing the stress at the solder joint and more effectively solving the problems of poor soldering and fatigue fracture of photovoltaic modules during hot and cold cycles.

[0021] Furthermore, by placing the buffer layer on the solder ribbon body within the area formed by at least two adjacent solder joints near the edge of the solar cell, the buffer layer can be positioned in areas of high stress. This allows for targeted reduction of stress between the encapsulant and the solder ribbon, more effectively addressing the issues of incomplete soldering and fatigue fracture during thermal cycling of photovoltaic modules. Additionally, compared to placing the buffer layer across the entire area of ​​the solder ribbon body, placing it only in areas of high stress can more effectively improve the light transmittance of the solder ribbon caused by the buffer layer.

[0022] Furthermore, by setting the surface of the buffer layer away from the solder strip body to a wavy shape, the refraction of light can be improved, thereby increasing the light transmittance of the solder strip and reducing the impact of setting the buffer layer on the light transmittance of the photovoltaic module.

[0023] Furthermore, the photovoltaic modules and photovoltaic systems further provided by this utility model based on the aforementioned composite welding strip, since including the aforementioned composite welding strip, possess the beneficial effects of the aforementioned composite welding strip. Compared with the photovoltaic modules and photovoltaic systems before the improvement, the photovoltaic modules of this utility model are less prone to problems such as poor solder joints and fatigue fractures, have a longer service life, a lower failure rate of the photovoltaic system, and a better user experience. Attached Figure Description

[0024] The preferred embodiments of this utility model are described below with reference to the accompanying drawings, in which: Figure 1This is a schematic diagram of the structure of the photovoltaic module of this utility model; Figure 2 This is a schematic diagram of the structure of the composite welding strip of this utility model after welding with two adjacent battery cells; Figure 3 This is a schematic diagram of the composite welding strip of this utility model; Figure 4 yes Figure 3 A cross-sectional view along line AA shows a structural schematic diagram of the composite solder strip in one embodiment. Figure 5 yes Figure 3 A cross-sectional view along line AA shows a structural schematic diagram of the composite solder strip in another embodiment; Figure 6 yes Figure 3 A cross-sectional view along line AA shows a structural schematic diagram of the composite solder strip in yet another embodiment. Figure 7 This is a stress cloud diagram of the weld joint after the composite welding strip in Example 1 is welded to the battery cell; Figure 8 This is a stress cloud diagram of the weld point after the composite welding strip in Example 2 is welded to the battery cell; Figure 9 This is a stress cloud diagram of the weld point after the composite welding strip in Example 3 is welded to the battery cell; Figure 10 This is a stress cloud diagram of the weld point after the composite welding strip in Comparative Example 1 is welded to the battery cell.

[0025] List of reference numerals in the attached diagram: 1. Battery cell; 2. Composite welding strip; 21. Welding strip body; 22. Buffer layer; 23. Receiving groove; 31. First adhesive film; 32. Second adhesive film; 41. Front panel; 42. Back panel; 5. Welding point. Detailed Implementation

[0026] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0027] It should be noted that in the description of this utility model, terms such as "upper," "lower," "inner," and "outer," which indicate direction or positional relationships, are based on the direction or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] Furthermore, it should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "setting," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0029] In a first aspect, the present invention provides a composite welding strip for connecting two adjacent cells of a photovoltaic module.

[0030] Specifically, please refer to Figure 1 , Figure 1 This is a structural schematic diagram of the photovoltaic module of this utility model.

[0031] like Figure 1 As shown, the photovoltaic module includes a front panel 41, a first encapsulant film 31, multiple solar cells 1, a second encapsulant film 32, and a back panel 42 stacked in sequence. The composite welding ribbon 2 includes a welding ribbon body 21 and a buffer layer 22 disposed on the welding ribbon body 21. The coefficient of thermal expansion of the buffer layer 22 is between the coefficient of thermal expansion of the welding ribbon body 21 and the coefficient of thermal expansion of the encapsulant film. The buffer layer 22 is located between the welding ribbon body 21 and the first encapsulant film 31 and / or the second encapsulant film 32.

[0032] By configuring the composite solder ribbon 2 to include a solder ribbon body 21 and a buffer layer 22 disposed on the solder ribbon body 21, and setting the coefficient of thermal expansion of the buffer layer 22 to be between that of the solder ribbon body 21 and the first adhesive film 31 and / or the second adhesive film 32, the interface stress caused by the large difference in the coefficient of thermal expansion between the solder ribbon and the adhesive film can be reduced by the buffer layer 22. This can prevent the photovoltaic module from experiencing poor soldering and fatigue fracture at the solder joint 5 due to the large difference in the coefficient of thermal expansion between the solder ribbon and the adhesive film during thermal cycling.

[0033] It should be noted that, in practical applications, those skilled in the art do not impose any restrictions on the specific value of the thermal expansion coefficient of the buffer layer 22, as long as the thermal expansion coefficient of the buffer layer 22 is between the thermal expansion coefficient of the solder ribbon body 21 and the thermal expansion coefficient of the adhesive film.

[0034] In some embodiments, those skilled in the art can set the coefficient of thermal expansion of the buffer layer 22 to a range of 150 ppm / ℃, 160 ppm / ℃, 170 ppm / ℃, 180 ppm / ℃, 190 ppm / ℃, 200 ppm / ℃, or any combination thereof. In some embodiments, the coefficient of thermal expansion of the buffer layer 22 is in the range of 150-200 ppm / ℃.

[0035] It should be noted that, in practical applications, those skilled in the art can set the modulus of the buffer layer 22 to a range of 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, or any combination of these values. In some embodiments, the modulus of the buffer layer 22 is in the range of 10-100 MPa.

[0036] It should also be noted that, in practical applications, those skilled in the art do not impose any limitations on the specific type of the buffer layer 22. For example, the buffer layer 22 can be set as one or any combination of silicone rubber, natural rubber, styrene-butadiene rubber, cis-butadiene rubber, and EPDM rubber.

[0037] In some embodiments, the buffer layer 22 is silicone rubber.

[0038] It should be noted that, in practical applications, those skilled in the art can configure the buffer layer 22 to extend along the length direction of the solder strip body 21 and be disposed on the entire length of the solder strip body 21, or the buffer layer 22 can be configured to extend along the length direction of the solder strip body 21 and the length of the buffer layer is less than the length of the solder strip body 21, etc. Such adjustments and changes to the specific arrangement of the buffer layer 22 on the solder strip body 21 do not deviate from the principle and scope of this utility model, and should all be included within the protection scope of this utility model.

[0039] Preferably, the buffer layer 22 extends along the length direction of the solder strip body 21 and the length of the buffer layer 22 is less than the length of the solder strip body 21.

[0040] By setting the length of the buffer layer 22 to be less than the length of the solder ribbon body 21, it is possible to avoid setting the buffer layer 22 along the entire length of the solder ribbon body 21, thereby reducing the impact of the buffer layer 22 on the light transmittance of the solder ribbon body 21 and improving the performance of the photovoltaic module.

[0041] It should be noted that, in practical applications, those skilled in the art can set the buffer layer 22 to be spaced apart on the solder strip body 21, or the buffer layer 22 can be set only in a local area of ​​the solder strip body 21, etc. Such adjustments and changes to the specific setting position of the buffer layer 22 on the solder strip do not deviate from the principle and scope of this utility model, and should all be included within the protection scope of this utility model.

[0042] In one specific embodiment, buffer layers 22 are spaced apart on the solder strip body 21.

[0043] In another specific embodiment, a plurality of solder joints 5 are formed between the solder ribbon body 21 and each battery cell 1, and a buffer layer 22 is disposed in a local area of ​​the solder ribbon body 21 and can cover the solder joints 5.

[0044] By setting the buffer layer 22 in a local area of ​​the solder ribbon body 21 and covering the solder joint 5, the coverage area of ​​the buffer layer 22 on the solder ribbon body 21 can be minimized, reducing the impact on the light transmittance of the solder ribbon body 21 caused by the buffer layer 22. On the other hand, the buffer layer 22 can be positioned at the solder joint 5, reducing the maximum stress at the solder joint 5 and reducing the problem of poor soldering and fatigue fracture at the solder joint 5 during the hot and cold cycle of the photovoltaic module.

[0045] It should be noted that in practical applications, the buffer layer 22 can be set at the position of the solder joint 5, or the buffer layer 22 can be set in the area formed by at least two adjacent solder joints 5, or the buffer layer 22 can be set in the area formed by multiple solder joints 5, etc. Such flexible adjustments and changes do not deviate from the principle and scope of this utility model and should be included within the protection scope of this utility model.

[0046] Please continue reading. Figure 2 , Figure 2 This is a schematic diagram of the structure of the composite welding strip 2 of this utility model after welding with two adjacent battery cells 1.

[0047] Preferably, such as Figure 2 As shown, the buffer layer 22 is disposed on the solder strip body 21 in the area formed by at least two adjacent solder joints 5 near the edge of the battery cell 1.

[0048] By setting the buffer layer 22 in the area formed by at least two adjacent solder joints 5 near the edge of the cell 1 on the solder ribbon body 21, the buffer layer 22 can be placed in the area with high stress, thereby specifically reducing the stress between the encapsulant film and the solder ribbon. This more effectively solves the problem of poor soldering and fatigue fracture of the solder joints 5 during the hot and cold cycles of photovoltaic modules. At the same time, compared with setting the buffer layer 22 in the entire area of ​​the solder ribbon body 21, setting the buffer layer 22 only in the area with high stress can also more effectively improve the problem of the light transmittance of the solder ribbon body 21 affected by the setting of the buffer layer 22.

[0049] It should be noted that, in practical applications, those skilled in the art do not impose any restrictions on the specific connection method between the buffer layer 22 and the solder ribbon body 21, as long as the buffer layer 22 and the solder ribbon body 21 can be connected.

[0050] In one specific embodiment, the composite solder ribbon 2 further includes an adhesive layer disposed between the solder ribbon body 21 and the buffer layer 22 and used to bond the buffer layer 22 to the solder ribbon body 21.

[0051] For example, the buffer layer 22 can be attached to the solder ribbon body 21 using silicone rubber self-adhesive tape.

[0052] In another specific embodiment, the buffer layer 22 is connected to the solder strip body 21 by a vulcanized adhesive layer.

[0053] Specifically, the buffer layer 22 is connected to the solder ribbon body 21 through a vulcanization bonding process. For example, in the vulcanization bonding process, the interface between the silicone rubber and the copper solder ribbon forms Si-O-Cu chemical bonds through a silane coupling agent, thereby forming a vulcanization bonding layer between the buffer layer 22 and the solder ribbon body 21.

[0054] In another possible embodiment, the buffer layer 22 may also be printed on the solder ribbon body 21.

[0055] It should be noted that the surface of the buffer layer 22 away from the solder ribbon body 21 can be set as a planar shape, or it can be set as a wavy shape, or it can be set as a textured structure, etc. Such specific adjustments and changes to the surface structure of the buffer layer 22 do not deviate from the principle and scope of this utility model and should be included within the protection scope of this utility model.

[0056] Preferably, the surface of the buffer layer 22 on the side away from the solder strip body 21 is configured as a wavy line.

[0057] This setup improves light refraction, thereby enhancing the light transmittance of the solder strip and reducing the impact of the buffer layer 22 on the light transmittance of the photovoltaic module.

[0058] It should be noted that, in practical applications, those skilled in the art can set the buffer layer 22 only on the surface of the solder strip body 21 away from the welding surface, that is, the buffer layer 22 only covers one surface of the solder strip body 21, or the buffer layer 22 can be set to wrap around the top of the solder strip body 21, etc. Such adjustments and changes to the specific setting of the buffer layer 22 on the solder strip body do not deviate from the principle and scope of this utility model, and should all be included within the protection scope of this utility model.

[0059] The following is combined with Figures 3 to 6 A detailed introduction will be given, including, Figure 3 This is a schematic diagram of the composite welding strip 2 of this utility model; Figure 4 yes Figure 3 A cross-sectional view along line AA shows a structural schematic diagram of the composite welding strip 2 in one embodiment. Figure 5 yes Figure 3 A cross-sectional view along line AA shows a structural schematic diagram of the composite welding strip 2 in another embodiment; Figure 6 yes Figure 3 A cross-sectional view along line AA shows a structural schematic diagram of the composite welding strip 2 in another embodiment.

[0060] In one specific embodiment, such as Figure 4 As shown, the ribbon body 21 has a welding surface for welding with the battery cell 1, and the buffer layer 22 is disposed at least on the surface of the ribbon body 21 away from the welding surface.

[0061] In another specific embodiment, such as Figure 5 and Figure 6 As shown, a receiving groove 23 adapted to the welding strip body 21 is formed on the inner side of the buffer layer 22. When assembled, the welding strip body 21 is located in the receiving groove 23, and the welding surface of the welding strip body 21 is exposed from the receiving groove 23 so as to be welded to the battery cell 1.

[0062] It should be noted that the present invention does not impose any limitation on the specific shape of the buffer layer 22. For example, the cross-section of the buffer layer 22 can be set as a "U" shape, and the cross-section of the solder strip body 21 can be a rectangular shape. Alternatively, the cross-section of the solder strip body 21 can be set as a T shape, and the surfaces of the buffer layer 22 can be used to form a T-shaped receiving groove 23. Such adjustments and changes to the specific structural forms of the buffer layer 22 and the solder strip body 21 do not deviate from the principle and scope of the present invention and should be included within the protection scope of the present invention.

[0063] In some embodiments, the thermal conductivity of the ends of the composite solder strip 2 is higher than that of the middle of the composite solder strip 2.

[0064] With this setup, since the ends of the composite welding ribbon 2 are welded to the battery cells while there are no welding points in the middle, the thermal conductivity of the ends of the composite welding ribbon 2 is higher than that of the middle of the composite welding ribbon 2. This allows the heat generated at the welding point 5 to be quickly conducted to the welding ribbon body 21 or the heat dissipation structure, reducing the accumulation of heat on the surface of the battery cell 1. This reduces the impact of heat loss on power generation efficiency and avoids physical damage to the battery cell 1 caused by local high temperatures, thus extending the overall lifespan of the module.

[0065] In some embodiments, the conductivity at the end of the composite solder strip 2 is greater than the conductivity in the middle of the composite solder strip 2.

[0066] With this setup, since the ends of the composite welding ribbon 2 are welded to the solar cells while there are no weld points in the middle, the conductivity of the ends of the composite welding ribbon 2 is greater than that of the middle part. This reduces the contact resistance between the ends and the electrodes of the solar cell 1, allowing the current to be transmitted more smoothly between adjacent solar cells 1, reducing energy loss during current transmission, and ultimately improving the overall power generation efficiency of the photovoltaic module.

[0067] In some embodiments, the adhesiveness of the ends of the composite solder strip 2 is less than that of the middle portion of the composite solder strip 2.

[0068] This design facilitates position adjustment during installation and ensures a tight bond between the central adhesive layer and the encapsulation layer, guaranteeing a secure overall fixation of the solder strip and preventing failures such as loose connections and interrupted current transmission due to insufficient adhesion during long-term use.

[0069] It should be noted that although the above three embodiments describe the relationship between the thermal conductivity, electrical conductivity, and adhesiveness of the ends and the middle of the composite solder strip 2, this is not limiting. For example, the thermal conductivity, electrical conductivity, and adhesiveness at all locations on the composite solder strip 2 can be set to be the same. Alternatively, the thermal conductivity of the ends of the composite solder strip 2 can be higher than that of the middle, and the electrical conductivity of the ends can be higher than that of the middle. Furthermore, the thermal conductivity of the ends of the composite solder strip 2 can be higher than that of the middle, and the adhesiveness of the ends can be lower than that of the composite solder strip 2. Alternatively, the conductivity of the ends of the composite welding strip 2 can be greater than that of the middle of the composite welding strip 2, and the viscosity of the ends of the composite welding strip 2 can be less than that of the middle of the composite welding strip 2. Or, the thermal conductivity of the ends of the composite welding strip 2 can be higher than that of the middle of the composite welding strip 2, and the conductivity of the ends of the composite welding strip 2 can be greater than that of the middle of the composite welding strip 2, and the viscosity of the ends of the composite welding strip 2 can be less than that of the middle of the composite welding strip 2, etc. Such flexible adjustments and changes do not deviate from the principle and scope of this utility model, and should all be included within the protection scope of this utility model.

[0070] In a second aspect, the present invention also provides a photovoltaic module.

[0071] Specifically, such as Figure 1 As shown, the photovoltaic module includes a front panel 41, a first encapsulant film 31, a plurality of solar cells 1, a second encapsulant film 32, a back panel 42, and a composite welding ribbon 2 as described in any of the first aspects, wherein the composite welding ribbon 2 is used to connect two adjacent solar cells 1 and the composite welding ribbon 2 is disposed between the solar cell 1 and the first encapsulant film 31 and / or the second encapsulant film 32.

[0072] It should be noted that, in practical applications, those skilled in the art can arrange the composite welding ribbon 2 only between the first adhesive film 31 and the battery cell 1, or the composite welding ribbon 2 only between the second adhesive film 32 and the battery cell 1, or the composite welding ribbon 2 can be arranged simultaneously between the first adhesive film 31 and the battery cell 1 and between the second adhesive film 32 and the battery cell 1, etc. Such adjustments and changes to the specific arrangement position of the composite welding ribbon 2 do not deviate from the principle and scope of this utility model, and should all be included within the protection scope of this utility model.

[0073] For example, such as Figure 1 As shown, the composite welding strip 2 is simultaneously disposed between the second adhesive film 32 and the battery cell 1.

[0074] In a third aspect, the present invention also provides a photovoltaic system, which includes the photovoltaic modules described in the second aspect.

[0075] The composite welding strip 2 of this utility model is described below, taking the buffer layer 22 as silicone rubber as an example and in conjunction with the following embodiments.

[0076] Example 1: The composite solder ribbon 2 in Example 1 includes a solder ribbon body 21 and a buffer layer 22. The buffer layer 22 is made of silicone rubber and has a modulus of 100 MPa. The buffer layer 22 is only disposed on the solder ribbon body 21 within the area formed by two adjacent solder joints 5 near the edge of the solar cell 1 (e.g., Figure 2 (As shown).

[0077] Example 2: The buffer layer 22 in this embodiment is the same as that in embodiment 1. The only difference between this embodiment and embodiment 1 is that the modulus of the buffer layer 22 is different from that in embodiment 1. In this embodiment, the modulus of the buffer layer 22 is 10 MPa.

[0078] Example 3: The buffer layer 22 in this embodiment has the same modulus as that in embodiment 1. The only difference between this embodiment and embodiment 1 is that the location of the buffer layer 22 is different from that in embodiment 1. In this embodiment, the buffer layer 22 is disposed along the entire length of the solder strip body 21.

[0079] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the solder strip body 21 in Comparative Example 1 does not have a buffer layer 22.

[0080] Experimental example: The composite welding strip 2 from Examples 1 to 3 and Comparative Example 1 were welded to the solar cell 1 to assemble a photovoltaic module. The stress at weld point 5 was simulated, and the maximum stress at weld point 5 was obtained. Specific results are shown in Table 1 below. Figures 7 to 10 As shown in the figure, Figure 7 This is a stress cloud diagram of the weld joint after the composite welding strip in Example 1 is welded to the battery cell; Figure 8 This is a stress cloud diagram of the weld point after the composite welding strip in Example 2 is welded to the battery cell; Figure 9 This is a stress cloud diagram of the weld point after the composite welding strip in Example 3 is welded to the battery cell; Figure 10 This is a stress cloud diagram of the weld point after the composite welding strip in Comparative Example 1 is welded to the battery cell.

[0081] Table 1: Test data for the examples and comparative examples From Table 1 and Figures 7 to 10 The data shows that: 1. Comparing the data of Examples 1 to 3 with Comparative Example 1, the maximum stress at solder joint 5 in Examples 1 to 3 is significantly less than the maximum stress at solder joint 5 in Comparative Example 1. This indicates that setting a buffer layer 22 on the solder ribbon body 21 can significantly reduce the stress at solder joint 5. In other words, the composite solder ribbon 2 of this utility model can effectively reduce the interface stress between the solder ribbon and the adhesive film caused by the large difference in the coefficient of thermal expansion, thereby effectively solving the problem of poor soldering and fatigue fracture at solder joint 5 in photovoltaic modules during hot and cold cycles. 2. Comparing the data of Example 1 and Example 3, the maximum stress at solder joint 5 in Example 1 and Example 3 is not much different, indicating that setting a buffer layer 22 in the area formed by two adjacent solder joints 5 near the edge of the cell 1 on the solder ribbon body 21 can effectively reduce the stress at solder joint 5, effectively solving the problem of poor soldering and fatigue fracture of solder joint 5 in photovoltaic modules during hot and cold cycles. Furthermore, setting a buffer layer 22 in the area formed by two adjacent solder joints 5 near the edge of the cell 1 on the solder ribbon body 21 can also reduce the impact of setting the buffer layer 22 on the light transmittance of the solder ribbon body 21. 3. Comparing the data of Example 1 and Example 2, the maximum stress at solder joint 5 in Example 2 is significantly less than the maximum stress at solder joint 5 in Example 1. Therefore, using a buffer layer 22 with a lower modulus can be more effective in reducing the maximum stress at solder joint 5. Using a buffer layer 22 with a lower modulus can more effectively solve the problem of poor soldering and fatigue fracture at solder joint 5 of photovoltaic modules during hot and cold cycles.

[0082] The technical solution of this utility model has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the protection scope of this utility model is obviously not limited to these specific embodiments. Without departing from the principle of this utility model, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of this utility model.

Claims

1. A composite welding strip for connecting two adjacent solar cells (1) of a photovoltaic module, the photovoltaic module comprising a front panel (41), a first encapsulating film (31), a plurality of solar cells (1), a second encapsulating film (32), and a back panel (42) stacked sequentially, characterized in that, The composite solder ribbon (2) includes a solder ribbon body (21) and a buffer layer (22) disposed on the solder ribbon body (21). The coefficient of thermal expansion of the buffer layer (22) is between the coefficient of thermal expansion of the solder ribbon body (21) and the coefficient of thermal expansion of the adhesive film. The buffer layer (22) is disposed at least between the solder strip body (21) and the first adhesive film (31) and / or the second adhesive film (32).

2. The composite welding strip according to claim 1, characterized in that, The coefficient of thermal expansion of the buffer layer (22) is in the range of 150-200 ppm / ℃; And / or, the modulus of the buffer layer (22) is in the range of 10-100 MPa.

3. The composite welding strip according to claim 1, characterized in that, The buffer layer (22) includes one or any combination of silicone rubber, natural rubber, styrene-butadiene rubber, butadiene rubber, and ethylene propylene diene monomer (EPDM) rubber.

4. The composite welding strip according to claim 1, characterized in that, The buffer layer (22) extends along the length direction of the solder strip body (21) and the length of the buffer layer (22) is less than the length of the solder strip body (21).

5. The composite welding strip according to claim 4, characterized in that, Multiple solder joints (5) are formed between the solder ribbon body (21) and each of the battery cells (1), and the buffer layer (22) is disposed in a local area of ​​the solder ribbon body (21) and can cover the solder joints (5).

6. The composite welding strip according to claim 5, characterized in that, The buffer layer (22) is disposed on the ribbon body (21) in the area formed by at least two adjacent solder points (5) near the edge of the battery cell (1).

7. The composite welding strip according to claim 1, characterized in that, The composite welding strip (2) further includes an adhesive layer, which is disposed between the welding strip body (21) and the buffer layer (22) and is used to bond the buffer layer (22) to the welding strip body (21); Alternatively, the buffer layer (22) is connected to the solder strip body (21) by a vulcanized adhesive layer.

8. The composite welding strip according to claim 1, characterized in that, The surface of the buffer layer (22) on the side away from the solder strip body (21) is wavy.

9. The composite welding strip according to claim 1, characterized in that, The welding strip body (21) has a welding surface for welding with the battery cell (1), wherein: The buffer layer (22) is provided at least on the surface of the solder strip body (21) away from the welding surface; And / or, the inner side of the buffer layer (22) forms a receiving groove (23) that is adapted to the welding strip body (21). When assembled, the welding strip body (21) is located in the receiving groove (23) and the welding surface of the welding strip body (21) is exposed from the receiving groove (23).

10. The composite welding strip according to claim 1, characterized in that, The thermal conductivity of the end of the composite welding strip (2) is greater than that of the middle part of the composite welding strip (2); And / or, the conductivity of the end of the composite solder strip (2) is greater than the conductivity of the middle part of the composite solder strip (2); And / or, the adhesion of the ends of the composite welding strip (2) is less than that of the middle part of the composite welding strip (2).

11. A photovoltaic module, characterized in that, The photovoltaic module includes a front panel (41), a first encapsulant film (31), a plurality of solar cells (1), a second encapsulant film (32), a back panel (42), and a composite welding ribbon (2) according to any one of claims 1 to 10, wherein the composite welding ribbon (2) is used to connect two adjacent solar cells (1) and the composite welding ribbon (2) is disposed between the solar cells (1) and the first encapsulant film (31) and / or the second encapsulant film (32).

12. A photovoltaic system, characterized in that, The photovoltaic system includes the photovoltaic module as described in claim 11.

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