Solder strip and back contact photovoltaic module

Abstract

The utility model relates to the technical field of photovoltaic modules, in particular to a solder strip and a back contact photovoltaic module. The utility model provides a solder strip and a back contact photovoltaic module. The solder strip comprises a metal substrate and a coating layer. The coating layer is coated outside the metal base material, comprises a first layer and a second layer and is positioned on two sides of the metal base material, and the thickness of the first layer is greater than that of the second layer. Wherein the first layer is used for being welded with a back contact photovoltaic module. According to the back contact photovoltaic module, the metal grid lines and the welding strips are located on the back faces of the battery pieces, only one faces of the welding strips are needed, the thicker first faces are used for welding, the welding stability can be guaranteed, and waste of a coating layer is reduced.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic module technology, and in particular to a photovoltaic module with a solder strip and back contact. Background Technology

[0002] Back-contact photovoltaic (PV) panels refer to PV panels that use IBC (Interdigitated Back Contact) technology.

[0003] IBC modules are characterized by having both the metal grid lines and solder ribbons located on the back of the cells, allowing the entire front side to absorb sunlight, thus improving light energy utilization and short-circuit current. The solder ribbon typically consists of a metal substrate and a solder layer covering the substrate, used for welding to the cells. In related technologies, the solder layer in IBC module solder ribbons is sometimes wasted, hindering cost reduction. Utility Model Content

[0004] This application provides a solder strip and a back-contact photovoltaic module. The solder strip can reduce cell cracking caused by overlay welding and reduce waste of the cladding layer.

[0005] This application provides a solder strip comprising: a metal substrate; and a cladding layer covering at least a portion of the metal substrate.

[0006] Along the thickness direction of the solder strip, the cladding layer includes a first layer and a second layer, and the first layer and the second layer are located on opposite sides of the metal substrate along the thickness direction, and the thickness of the first layer is different from the thickness of the second layer.

[0007] In this solution, we describe an example where the thickness of the first layer is greater than the thickness of the second layer. The first layer is the part of the back-contact photovoltaic module used for welding to the solar cell, and the second layer is the part that is away from the solar cell along its thickness direction. When the solar cell is welded via the solder ribbon, the first layer of the ribbon's coating is welded to the solar cell. Due to the greater thickness of the first layer, the welding reliability between the ribbon and the solar cell is high. The second layer, however, is not welded to the solar cell. A smaller thickness of the second layer avoids the problem of excessive solder not being fully spread in the area where the ribbon and solar cell contact after melting, causing accumulation in other areas. In other words, a smaller second layer thickness reduces the risk of solder buildup during welding, which can lead to cracks in the solar cell, thus improving the efficiency of the photovoltaic module. Furthermore, a smaller second layer thickness reduces the overall amount of coating material used in the solder ribbon, thereby reducing the cost of the solder ribbon.

[0008] In one possible design, the first layer is used for welding to the battery cell, and the thickness D2 of the second layer satisfies: 0≤D2≤5μm.

[0009] In this design, when the thickness D2 of the second layer is too large, for example, greater than 5 μm, weld overlay problems can easily occur during the welding process, leading to cell cracking. Furthermore, since the second layer is not welded to the cell, an excessively thick second layer results in material waste. Therefore, in this embodiment, the thickness of the second layer should be as small as possible, and greater than 0, meaning the thickness D2 of the second layer satisfies: 0 μm ≤ D2 ≤ 5 μm. This ensures the coating layer has sufficient thickness to isolate oxygen and prevent oxidation of the metal substrate, while also preventing excessive thickness that could lead to weld overlay during welding and cell cracking, thus minimizing coating layer waste.

[0010] In one possible design, the thickness D1 of the first layer satisfies: 16μm≤D1≤24μm.

[0011] In this solution, if the thickness D1 of the first layer is too small, for example, less than 16 μm, when the solder ribbon and the battery cell are welded through the first layer, too little solder will be melted, posing a risk that the gap between the solder ribbon and the battery cell cannot be filled, resulting in low welding reliability and poor circuit conductivity between the battery cells. Conversely, if the thickness D1 of the first layer of the solder ribbon is too large, for example, greater than 24 μm, too much solder will be melted during welding, posing a risk of cell cracking due to excessive solder buildup and wasting the coating material. In this embodiment, when 16 μm ≤ D1 ≤ 24 μm, not only can the individual battery cells be reliably connected during the welding process between the solder ribbon and the battery cell, but it also prevents cell cracking caused by excessive solder buildup during welding due to an excessively thick first layer, and reduces waste of the coating material.

[0012] In one possible design, the thickness D1 of the first layer is 16 μm, and the thickness D2 of the second layer is 3 μm. This design allows for a moderate thickness of the coating layer on the solder ribbon, effectively preventing oxidation of the metal substrate. It also avoids an excessively thick second layer when the solder ribbon is used for back-contact photovoltaic modules, thus preventing cell cracking due to weld over-soldering and reducing waste of the coating layer.

[0013] In one possible design, the overlay layer further includes a sidewall connected to the first layer and the second layer, the sidewall covering the metal substrate circumferentially, and the thickness D3 of the sidewall satisfying: 6μm≤D3≤10μm.

[0014] In this solution, when the sidewall thickness is too small, for example, less than 6 μm, the cladding layer is too thin, and the resistivity of the metal substrate may increase due to oxidation or corrosion, leading to increased power loss. When the sidewall thickness is too large, for example, greater than 10 μm, the excessively thick cladding layer increases the hardness of the solder ribbon, making it difficult to adapt to the bending or thermal expansion of the photovoltaic cell, easily causing fatigue fracture. Furthermore, the sidewall cladding layer does not participate in welding, resulting in waste of the cladding layer. In this embodiment, when the sidewall thickness satisfies 6 μm ≤ D3 ≤ 10 μm, the cladding layer thickness is moderate, which can prevent substrate oxidation without significantly increasing resistance, effectively block moisture and corrosive media, has strong corrosion resistance, and optimizes the amount of cladding layer material used, achieving a balance between cost control and solder ribbon performance.

[0015] In one possible design, the metal substrate has an embossed surface near the second layer. By embossing the surface of the metal substrate near the second layer, the reflective area of ​​the light-receiving surface of the metal substrate can be increased, improving the reflectivity of the metal substrate and thus further improving the light utilization rate of the photovoltaic module.

[0016] In one possible design, the embossing has a depth greater than 3 μm and a width less than 0.2 mm.

[0017] In this solution, when the embossing depth is too small, for example, less than 3μm, the total surface area embossed is small, resulting in a small reflective surface area on the light-receiving surface of the metal substrate, poor reflectivity, and an inability to effectively improve the light utilization rate of the photovoltaic module. When the embossing width is too large, for example, greater than 0.2mm, the embossing distribution is too sparse, resulting in a small reflective surface area on the light-receiving surface of the metal substrate, poor reflectivity, and an inability to effectively improve the light utilization rate of the photovoltaic module. In this embodiment, when the embossing depth is greater than 3μm and the width is less than 0.2mm, the reflective area of ​​the light-receiving surface of the metal substrate can be effectively increased, thereby improving the light utilization rate of the photovoltaic module.

[0018] In one possible design, the thickness D4 of the metal substrate satisfies: 0.18mm ≤ D4 ≤ 0.24mm. When the thickness D4 of the metal substrate is too small, for example, less than 0.18mm, the current that the metal substrate can withstand is relatively small, resulting in decreased conductivity. When the thickness D4 of the metal substrate is too large, for example, greater than 0.24mm, the metal substrate is too thick, resulting in high resistivity, excessive power consumption, and poor flexibility, causing inconvenience during use.

[0019] In this design, when 0.18mm ≤ D4 ≤ 0.24mm, the volume of the metal substrate is moderate, resulting in a large current-carrying capacity and low resistivity, thereby reducing power loss and improving the conversion efficiency of the photovoltaic module. Furthermore, a metal substrate with a thickness D4 of 0.18~0.24mm possesses sufficient mechanical strength to withstand the thermal and mechanical stresses during welding, preventing breakage or deformation, and maintaining a certain degree of flexibility in the solder strip, facilitating bending and laying between photovoltaic module cells. A metal substrate with a thickness D4 of 0.18~0.24mm also minimizes material usage, reducing production costs.

[0020] In one possible design, the cross-sectional shape of the metal substrate is any one of rectangular, semi-elliptical, elliptical, or irregular. In actual production, by selecting different cross-sectional shapes, the metal substrate can meet the requirements of different application scenarios regarding the mechanical properties, electrical conductivity, welding performance, and ease of assembly of the welding strip. Rectangular, semi-elliptical, elliptical, and irregular cross-sections each have their advantages, and users can choose the most suitable shape according to specific needs to achieve the best technical effect and economy.

[0021] In one possible design, the back-contact photovoltaic module includes: a plurality of solar cells; and solder ribbons located on the back of the solar cells and connecting adjacent solar cells.

[0022] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the stacked structure of the photovoltaic module provided in this application in a specific embodiment;

[0024] Figure 2 This is a cross-sectional view of adjacent solar cells connected by solder strips as provided in this application;

[0025] Figure 3 for Figure 2 A cross-sectional view of the solder strip in one specific embodiment;

[0026] Figure 4 for Figure 2 A cross-sectional view of the solder strip in another specific embodiment;

[0027] Figure 5 for Figure 3 A top view of the metal substrate of the solder strip.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1- Welding strip;

[0030] 11-Metal substrate;

[0031] 111 - Embossing;

[0032] 12-Covering layer;

[0033] 121 - First Floor;

[0034] 122 - Second layer;

[0035] 123 - Sidewall;

[0036] 2- Battery string;

[0037] 21-cell battery;

[0038] 3-Cover plate;

[0039] 4- Front adhesive film;

[0040] 5- Backing adhesive film;

[0041] 6-Back panel.

[0042] 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. Detailed Implementation

[0043] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0044] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0045] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0046] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0047] As a renewable and clean energy source, solar energy has led to extensive research into photovoltaic (PV) power generation technology, resulting in the rapid development of the PV power generation industry in recent years. A typical PV power generation system includes multiple components such as PV modules, DC-DC converters, and inverters. PV modules perform photoelectric conversion, transforming the energy from sunlight into direct current (DC) electricity. DC-DC converters collect electrical energy from the PV modules and convert the voltage before outputting it. Inverters receive the electrical energy from the DC-DC converters and convert it into alternating current (AC) electricity. The AC electricity is then fed into the grid via a grid-connected transformer, thus enabling the PV power generation system to connect to the grid.

[0048] Photovoltaic modules are the core components of a photovoltaic power generation system. (Refer to...) Figure 1 , Figure 1 This is a schematic diagram of the stacked structure of a photovoltaic module provided in an embodiment of this application. The photovoltaic module includes a cover plate 3, a cell string 2, and a back sheet 6 stacked along a first direction. The cell string 2 includes a plurality of cell cells 21 arranged along a second direction. The cover plate 3 is located on the light-facing side of the cell cells 21, used to transmit sunlight and also to improve the waterproof and moisture-proof capabilities of the photovoltaic module. The back sheet 6 is located on the shaded side of the cell cells 21, and the cover plate 3 and the back sheet 6 are used to seal the cell cells 21.

[0049] Adjacent cells 21 in the battery string 2 are connected by solder ribbon 1. In this embodiment, the cell 21 can be a back contact (BC) cell; therefore, the photovoltaic module in this embodiment is a back contact photovoltaic module. In a BC cell, the emitter, surface field, and metal electrodes are all located on the back side of the cell and are arranged in a cross-directional pattern. The front side of the cell 21 uses a SiNx / SiOx double-layer anti-reflection passivation film, ensuring that there are no metal electrodes obstructing the front of the cell. This allows the cell 21 to receive more incident light, reducing optical loss and improving photoelectric conversion efficiency.

[0050] The photovoltaic module also includes a front encapsulating film 4 and a back encapsulating film 5. The front encapsulating film 4 is located between the cover plate 3 and the cell string 2, and the back encapsulating film 5 is located between the back sheet 6 and the cell string 2. During the manufacturing process, the cover plate 3, the front encapsulating film 4, multiple cell strings 21, the back encapsulating film 5, and the back sheet 6 are laminated. During lamination, the front encapsulating film 4 and the back encapsulating film 5 encapsulate the cell strings 21, preventing external environmental factors from affecting their performance. After lamination, the front encapsulating film 4 connects the cover plate 3 and the cell strings 21, and the back encapsulating film 5 connects the back sheet 6 and the cell strings 21. In addition to their connecting function, the front encapsulating film 4 and the back encapsulating film 5 also serve to transmit light, provide support, protect, and insulate.

[0051] The front adhesive film 4 and the back adhesive film 5 can be made of the same material or different materials. The front adhesive film 4 and the back adhesive film 5 can be made of one of the following materials: ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), polyvinyl butyral (PVB), etc., or they can be EPE film (EVA-POE-EVA co-extrusion structure) or EP film (EVA-POE co-extrusion structure).

[0052] This application provides a solder strip 1 for back-contact photovoltaic modules. For example... Figure 2 As shown, the solder ribbon 1 is used to connect the solar cells 21 of the back photovoltaic module. From Figure 2 It can be seen that the solder ribbon 1 is located on the back of each cell 21, that is, the solder ribbon 1 is located on the back side of each cell 21, so that the light-facing side of each cell 21 is not blocked by the solder ribbon 1.

[0053] Specifically, such as Figure 3 , Figure 4 As shown, the solder strip 1 includes: a metal substrate 11 and a cladding layer 12, wherein the cladding layer 12 covers at least a portion of the structure of the metal substrate 11, i.e., as shown in the figure. Figure 3 As shown, the cladding layer 12 can cover a portion of the structure of the metal substrate 11, or, as... Figure 4 As shown, the cladding layer 12 can also cover the entire structure of the metal substrate 11. When welding the solder ribbon 1 to the battery cell 21, the cladding layer 12 melts to achieve the welding of the solder ribbon 1 to the battery cell 21.

[0054] In this embodiment, along the thickness direction of the solder strip 1, the cladding layer 12 includes a first layer 121 and a second layer 122, located on opposite sides of the metal substrate 11 along the thickness direction. The thicknesses of the first layer 121 and the second layer 122 are different; that is, the thickness of one of the first layer 121 and the second layer 122 is less than the other. In this embodiment, the example of the first layer 121 having a greater thickness than the second layer 122 is used for description. Here, the first layer 121 is the part in the back-contact photovoltaic module used for welding with the solar cell 21, and the second layer 122 is the part that is away from the solar cell 21 along the thickness direction.

[0055] In this embodiment, when the solar cell 21 is welded via the solder ribbon 1, the first layer 121 of the coating layer 12 in the solder ribbon 1 is welded to the solar cell 21. Due to the large thickness of the first layer 121, the welding reliability between the solder ribbon 1 and the solar cell 21 is high. The second layer 122 is not welded to the solar cell 21. A smaller thickness of the second layer 122 avoids excessive solder buildup during welding, which would prevent the solder from being completely spread in the contact area between the solder ribbon 1 and the solar cell 21, causing accumulation in other areas. In other words, a smaller thickness of the second layer 122 reduces the risk of solder buildup during welding, which could lead to cracks in the solar cell 21, thereby improving the efficiency of the photovoltaic module. Furthermore, a smaller thickness of the second layer 122 reduces the overall amount of coating layer 12 used in the solder ribbon 1, thus reducing the cost of the solder ribbon 1.

[0056] In some specific embodiments, the metal substrate 11 can be made of copper, and the cladding layer 12 can be made of tin.

[0057] In one specific embodiment, such as Figure 2 , Figure 3 As shown, the thickness D2 of the second layer 122 of solder strip 1 satisfies: 0μm≤D2≤5μm. For example, the thickness of the second layer 122 can be: 1μm, 2μm, 3μm, or 4μm.

[0058] When the thickness D2 of the second layer 122 is too large (e.g., greater than 5 μm), weld overlay problems are prone to occur during the welding process, leading to cracking of the battery cell 212. Moreover, since the second layer 122 is not welded to the battery cell 21, an excessively thick second layer 122 will result in material waste of the covering layer 12. Therefore, in this embodiment, the thickness of the second layer 122 should be as small as possible, and the thickness of the second layer 122 should be greater than 0, that is, the thickness D2 of the second layer 122 satisfies: 0 μm ≤ D2 ≤ 5 μm. The covering layer 12 has sufficient thickness to isolate oxygen and prevent oxidation of the metal substrate 11, and the covering layer 12 is not too thick to cause weld overlay during the welding process, which would lead to cracking of the battery cell 21, while also minimizing the waste of the covering layer 12.

[0059] On the other hand, the thickness D1 of the first layer 121 satisfies: 16μm≤D1≤24μm. For example, D1 can be: 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm.

[0060] If the thickness D1 of the first layer 121 is too small (e.g., less than 16 μm), when the solder ribbon 1 and the battery cell 21 are welded through the first layer 121, too little solder will be molten, posing a risk that the gap between the solder ribbon 1 and the battery cell 21 cannot be filled, resulting in low welding reliability and poor circuit conductivity between the battery cells 212. Conversely, if the thickness D1 of the first layer 121 of the solder ribbon 1 is too large (e.g., greater than 24 μm), too much solder will be molten during welding, posing a risk of solder buildup leading to cracking of the battery cell 21 and wasting material in the coating layer 12. In this embodiment, when 16 μm ≤ D1 ≤ 24 μm, during the welding process between the solder ribbon 1 and the battery cell 21, not only can the individual battery cells 21 be reliably connected, but the excessive thickness of the first layer 121 can also prevent solder buildup during welding, thus reducing the waste of the coating layer 12.

[0061] In one specific embodiment, such as Figure 3 , Figure 4 As shown, the thickness D1 of the first layer 121 can be 16μm, and the thickness D2 of the second layer 122 can be 3μm, so that the thickness of the coating layer 12 of the solder ribbon 1 is moderate, which can effectively prevent the metal substrate 11 from oxidizing, and also avoid the second layer 122 of the coating layer 12 being too thick when the solder ribbon 1 is used for back contact photovoltaic modules, thereby avoiding the occurrence of over-welding during welding that could cause the cell 21 to crack, and reducing the waste of the coating layer 12.

[0062] In another specific embodiment, such as Figure 4 As shown, the cladding layer 12 also includes a sidewall 123 connected to the first layer 121 and the second layer 122, wherein the sidewall 123 covers the metal substrate 11 circumferentially. That is, in this embodiment, the cladding layer 12 completely encloses the metal substrate 11, thereby further preventing the metal substrate 11 from oxidizing.

[0063] The thickness D3 of the sidewall 123 satisfies: 6μm≤D3≤10μm. For example, the thickness of the sidewall 123 can be 6μm, 7μm, 8μm, 9μm, or 10μm.

[0064] When the thickness of the sidewall 123 is too small (e.g., less than 6 μm), the cladding layer 12 is too thin, and the resistivity of the metal substrate 11 may increase due to oxidation or corrosion, leading to increased power loss. When the thickness of the sidewall 123 is too large (e.g., greater than 10 μm), the excessively thick cladding layer 12 increases the hardness of the solder ribbon 1, making it difficult to adapt to the bending or thermal expansion of the photovoltaic cell 21, which can easily lead to fatigue fracture. Furthermore, the cladding layer 12 of the sidewall 123 does not participate in welding, resulting in waste of the cladding layer 12. In this embodiment, when the thickness of the sidewall 123 satisfies 6 μm ≤ D3 ≤ 10 μm, the thickness of the cladding layer 12 is moderate. It can prevent the oxidation of the substrate without significantly increasing the resistance, and it can effectively block moisture and corrosive media, exhibiting strong corrosion resistance. Moreover, the material usage of the cladding layer 12 is optimized, achieving a balance between cost control and the performance of the solder ribbon 1.

[0065] The above describes the specific structure and parameters of the cladding layer 12 of the solder strip 1. The specific structure and parameters of the metal substrate 11 are described in detail below.

[0066] In one specific embodiment, such as Figure 5 As shown, the metal substrate 11 has embossing 111 on the surface near the second layer 122. The shape of the embossing 111 includes, but is not limited to, cross embossing 111. By embossing the surface of the metal substrate 11 near the second layer 122, the reflective area of ​​the light-receiving surface of the metal substrate 11 can be increased, the reflectivity of the metal substrate 11 can be improved, and thus the light utilization rate of the photovoltaic module can be further improved.

[0067] Specifically, the embossing 111 on the surface of the metal substrate 11 near the second layer 122 has a depth greater than 3μm and a width less than 0.2mm.

[0068] When the depth of the embossing 111 is too small (e.g., less than 3 μm), the total surface area embossed by the embossing 111 is small, resulting in a small reflective surface area on the light-receiving surface of the metal substrate 11, poor reflectivity, and an inability to effectively improve the light utilization rate of the photovoltaic module. When the width of the embossing 111 is too large (e.g., greater than 0.2 mm), the distribution of the embossing 111 is too sparse, resulting in a small reflective surface area on the light-receiving surface of the metal substrate 11, poor reflectivity, and an inability to effectively improve the light utilization rate of the photovoltaic module. In this embodiment, when the depth of the embossing 111 is greater than 3 μm and the width is less than 0.2 mm, the reflective area of ​​the light-receiving surface of the metal substrate 11 can be effectively increased, thereby improving the light utilization rate of the photovoltaic module.

[0069] In one specific embodiment, the thickness D4 of the metal substrate 11 satisfies: 0.18mm ≤ D4 ≤ 0.24mm. For example, D4 ​​can be 0.19mm, 0.2mm, 0.21mm, 0.22mm, or 0.23mm.

[0070] When the thickness D4 of the metal substrate 11 is too small (e.g., less than 0.18 mm), the current that the metal substrate 11 can withstand will be small, and the conductivity will decrease. When the thickness D4 of the metal substrate 11 is too large (e.g., greater than 0.24 mm), the metal substrate 11 is too thick, which will result in a large resistivity, excessive power consumption, and poor flexibility, causing inconvenience during use.

[0071] In this embodiment, when 0.18mm ≤ D4 ≤ 0.24mm, the volume of the metal substrate 11 is moderate, resulting in a large current-carrying capacity and low resistivity, thereby reducing power loss and improving the conversion efficiency of the photovoltaic module. Furthermore, the metal substrate 11 with a thickness D4 of 0.18~0.24mm has sufficient mechanical strength to withstand the thermal and mechanical stresses during welding, preventing breakage or deformation, and maintaining a certain degree of flexibility in the welding ribbon 1, facilitating bending and laying of the welding ribbon 1 between the photovoltaic module cells 21. The metal substrate 11 with a thickness D4 of 0.18~0.24mm also minimizes material usage and reduces production costs.

[0072] In one specific embodiment, the cross-sectional shape of the metal substrate 11 is any one of rectangular, semi-elliptical, elliptical, or irregular. In actual production, by selecting different cross-sectional shapes, the metal substrate 11 can meet the requirements of different application scenarios for the mechanical properties, electrical conductivity, welding performance, and ease of assembly of the welding strip 1. Rectangular, semi-elliptical, elliptical, and irregular cross-sections each have their advantages, and users can choose the most suitable shape according to specific needs to achieve the best technical effect and economy.

[0073] In summary, by applying different thicknesses to the first layer 121 and the second layer 122, this application reduces waste of the cladding layer 12 and lowers the risk of material accumulation during the welding process of the solder strip 1 in back contact with the photovoltaic module. Furthermore, by embossing the surface of the metal substrate 11, the reflective area of ​​the metal substrate 11 is increased, thereby improving the power generation efficiency of the photovoltaic module.

[0074] The above are merely specific embodiments of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the scope of the claims.

Claims

1. A welding strip, characterized in that, The welding strip (1) includes: Metal substrate (11); A covering layer (12) that covers at least a portion of the metal substrate (11); Along the thickness direction of the solder strip (1), the cladding layer (12) includes a first layer (121) and a second layer (122), and the first layer (121) and the second layer (122) are located on both sides of the metal substrate (11) along the thickness direction. The thickness of the first layer (121) is different from the thickness of the second layer (122).

2. The welding strip according to claim 1, characterized in that, The first layer (121) is used for welding to the battery cell (2), and the thickness D2 of the second layer (122) satisfies: 0≤D2≤5μm.

3. The welding strip according to claim 2, characterized in that, The thickness D1 of the first layer (121) satisfies: 16μm≤D1≤24μm.

4. The welding strip according to claim 2, characterized in that, The thickness D1 of the first layer (121) is 16 μm, and the thickness D2 of the second layer (122) is 3 μm.

5. A welding strip according to claim 2, characterized in that, The covering layer (12) also includes a sidewall (123) connected to the first layer (121) and the second layer (122), the sidewall (123) covering the metal substrate (11) in the circumferential direction, and the thickness D3 of the sidewall (123) satisfies: 6μm≤D3≤10μm.

6. The welding strip (1) according to claim 2, characterized in that, The metal substrate (11) has an embossed pattern (111) on the surface near the second layer (122).

7. A welding strip according to claim 6, characterized in that, The embossing (111) has a depth greater than 3 μm and a width less than 0.2 mm.

8. A welding strip according to any one of claims 1 to 7, characterized in that, The thickness D4 of the metal substrate (11) satisfies: 0.18mm≤D4≤0.24mm.

9. A welding strip according to any one of claims 1 to 7, characterized in that, The cross-sectional shape of the metal substrate (11) is any one of rectangular, semi-elliptical, elliptical, or irregular.

10. A back-contact photovoltaic module, characterized in that, The back-contact photovoltaic module includes: Multiple battery cells (2); A solder strip (1) is located on the back of the battery cell (2) and the solder strip (1) connects adjacent battery cells (2). Wherein, the welding strip (1) is the welding strip (1) according to any one of claims 1-9.

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