Back contact solar cell modules and photovoltaic systems

Abstract

The present application is applicable to the field of photovoltaic technology and provides a back-contact solar cell assembly and a photovoltaic system, including a composite welding tape and a plurality of back-contact solar cells, wherein the composite welding tape is arranged on the backlight surface of the plurality of back-contact solar cells, and the composite welding tape includes a first conductive layer; a second conductive layer, wherein the second conductive layer is arranged on the outer surface of the first conductive layer, the first conductive layer includes aluminum elements, and the second conductive layer includes copper elements or nickel elements; the mass ratio of the second conductive layer and the first conductive layer of the composite welding tape is the composite welding tape component ratio C, and the composite welding tape component ratio C is greater than or equal to 0.1. The present application controls the yield strength of the composite welding tape within a predetermined range, thereby avoiding the problem that the composite welding tape is prone to warping and causes warping of the battery cell, greatly reducing the cost compared with the traditional copper welding tape, thereby effectively reducing the production cost of the battery assembly.

Description

Technical Field

[0001] The present application belongs to the field of photovoltaic technology, and in particular relates to a back-contact solar cell module and a photovoltaic system. Background Art

[0002] Solar energy is an inexhaustible source of clean energy. With the development of the solar industry, photovoltaic installed capacity has continued to climb. With continuous technological innovation, the cost of electricity per kilowatt-hour continues to decline, and the demand for grid parity is also growing. Reducing costs and increasing efficiency has become a top priority for the industry. Conventional photovoltaic ribbons for photovoltaic modules are made of oxygen-free copper, which is relatively expensive to produce. With the continuous advancement of current module and cell technology, Topcon, heterojunction, and IBC have emerged, and the demand for ribbons is also constantly changing. While ensuring electrical conductivity, preparing low-cost ribbons to replace conventional oxygen-free copper ribbons, keeping ribbon costs low, and ensuring high quality and low prices is an urgent issue that needs to be addressed.

[0003] Although the current conventional composite welding tape has reduced the production cost, when a certain welding temperature is used for welding, the composite welding tape is very likely to warp due to the different thermal expansion coefficients of different metals, causing the contact part between the battery cell and the composite welding tape to be forced to deform, which in turn causes the battery cell to warp, resulting in battery cell cracking, and thus increasing the defective rate of battery components.

[0004] How to control the warping of the composite welding ribbon in the back-contact solar cell module becomes the key. This has positive significance for breaking the market's inherent perception of high efficiency and high cost of IBC batteries and enabling IBC batteries to gain a larger application market. Summary of the Invention

[0005] In a first aspect, the present application provides a back-contact solar cell module, aiming to solve the problem of how to control the warping of the composite welding ribbon in the back-contact solar cell module.

[0006] The present application is implemented as follows: a back-contact solar cell assembly includes a composite welding ribbon and a plurality of back-contact solar cells, the composite welding ribbon being arranged on the back-light surface of the plurality of back-contact solar cells, the composite welding ribbon including a first conductive layer; a second conductive layer, the second conductive layer being arranged on the outer surface of the first conductive layer, the first conductive layer including aluminum, and the second conductive layer including copper or nickel; the mass ratio of the second conductive layer to the first conductive layer of the composite welding ribbon is the composite welding ribbon component ratio C, the composite welding ribbon component ratio C is greater than or equal to 0.1, the composite welding ribbon has a first connecting portion, the first connecting portion is arranged between two adjacent back-contact solar cells, the angle a of the first connecting portion relative to the back-light surface of the back-contact solar cell is greater than 0° and less than or equal to 60°, the angle a and the yield strength σs of the composite welding ribbon satisfy the following relationship: (90 / 1.63) × cos a≤σs≤cos a × 90, wherein a is greater than 0° and less than or equal to 60°.

[0007] In the present application, the composite welding ribbon is arranged on the backlight surface of multiple back-contact solar cells. Compared with the double-sided cell structure, the composite welding ribbon is arranged on the single side of the back-contact solar cell in this way, which significantly reduces the degree of bending of the composite welding ribbon, making it possible to connect multiple back-contact solar cells without warping within the set yield strength range. By controlling the yield strength of the composite welding tape within a predetermined range, the problem of the composite welding tape being easily warped and causing warping of the battery cells can be avoided. The morphology, composition and size of the composite welding tape can be designed in a diversified manner to meet the process requirements of various types of solar cell modules. Compared with traditional copper welding tapes, the cost is greatly reduced, thereby effectively reducing the production cost of the battery modules. In addition, the present application also sets the angle a of the first connection portion of the composite welding tape relative to the backlight surface of the back-contact solar cell and the yield strength of the composite welding tape to satisfy the relationship: (90 / 1.63) × cos a≤σs≤cos a × 90, where a is greater than 0° and less than or equal to 60°, further ensuring that when the composite welding tape is used for string welding between battery cells, the composite welding tape and the battery cell have good fit, the welding is stable and not deformed, especially in the overlapping area of the battery cells, the composite welding tape can achieve a smooth transition connection, which can avoid the occurrence of composite welding tape cold welding and desoldering in the overlapping area of the battery cells.

[0008] Optionally, a plurality of the back-contact solar cells are arranged at intervals, and an angle a formed between the first connecting portion and the backlight surface of the back-contact solar cell is greater than 0° and less than or equal to 20°.

[0009] Optionally, an angle a formed between the first connecting portion and the backlight surface of the back-contact solar cell is greater than 0° and less than or equal to 10°.

[0010] Optionally, an angle a formed between the first connecting portion and the backlight surface of the back-contact solar cell is greater than 0° and less than or equal to 5°.

[0011] Optionally, a plurality of the back-contact solar cells are partially overlapped, and an angle a formed by the first connecting portion relative to the backlight surface of the back-contact solar cell is greater than or equal to 10° and less than or equal to 60°.

[0012] Optionally, an angle a formed between the first connecting portion and the backlight surface of the back-contact solar cell is greater than or equal to 10° and less than or equal to 45°.

[0013] Optionally, the composite welding strip component ratio C is greater than or equal to 0.2.

[0014] Optionally, the component ratio C of the composite welding strip ranges from 0.25 to 2.4.

[0015] Optionally, the composite welding tape further includes a composite structural layer, the first conductive layer and the second conductive layer are combined to form the composite structural layer, and the composite structural layer is arranged between the first conductive layer and the second conductive layer.

[0016] Optionally, the thickness of the composite structure layer is 0-30 microns.

[0017] Optionally, components of the composite structural layer include at least one of Al4Cu9, AlCu, Al2Cu, Al2Cu3, Al3Cu4 and Cu.

[0018] Optionally, the composite welding tape further includes a conductive connection layer, and the conductive connection layer is arranged on the surface of the second conductive layer.

[0019] Optionally, the thickness of the conductive connection layer is 1 to 20 microns.

[0020] Optionally, the conductive connection layer comprises at least one of Sn, Bi, and Pb.

[0021] Optionally, based on the first preset temperature, components of the conductive connection layer include Sn, Bi, and Pb; wherein the Bi content is 10% to 40%, the Sn content is 20% to 50%, and the Pb content is 30% to 60%.

[0022] Optionally, based on the second preset temperature, the components of the conductive connection layer include Sn and Pb; wherein the content of Sn is 50% to 70%, and the content of Pb is 30% to 50%.

[0023] Optionally, the resistance of the composite welding strip is greater than or equal to 60 milliohms and less than or equal to 150 milliohms.

[0024] Optionally, a connecting layer is further included, and the connecting layer is arranged between the first conductive layer and the second conductive layer.

[0025] Optionally, the tie layer comprises zinc.

[0026] Optionally, the composite welding strip is a flat welding strip.

[0027] Optionally, when the thickness of the composite welding strip is 0.1 mm, the width of the composite welding strip is less than 2.5 mm; or, when the width of the composite welding strip is 2.5 mm, the thickness of the composite welding strip is greater than 0.1 mm.

[0028] Optionally, when the width of the composite welding strip is 0.4~0.8mm and the thickness of the composite welding strip is 0.2~0.3mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 50~60MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 55~65MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 58~68MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 60~70MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 65~75MPa.

[0029] Optionally, when the width of the composite welding strip is 0.8~1.4 mm and the thickness of the composite welding strip is 0.12~0.2 mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 55~65 MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 60~70 MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 62~72 MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 65~75 MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 70~80 MPa.

[0030] Optionally, when the width of the composite welding strip is 1.4~1.8 mm and the thickness of the composite welding strip is 0.1~0.15 mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 55~65 MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 60~70 MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 62~72 MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 65~75 MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 70~80 MPa.

[0031] Optionally, when the width of the composite welding strip is 1.8~2.2 mm and the thickness of the composite welding strip is 0.12~0.2 mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 50~60 MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 55~65 MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 60~70 MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 62~72 MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 65~75 MPa.

[0032] Optionally, when the width of the composite welding strip is 1.8~2.2 mm and the thickness of the composite welding strip is 0.05~0.12 mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 50~60 MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 55~65 MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 60~70 MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 62~72 MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 65~75 MPa.

[0033] Optionally, when the width of the composite welding strip is 2.2~2.8 mm and the thickness of the composite welding strip is 0.12~0.2 mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 50~60 MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 55~65 MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 60~70 MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 62~72 MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 65~75 MPa.

[0034] Optionally, the composite welding strip is a round wire welding strip, and the diameter length of the composite welding strip is greater than or equal to 0.07 mm and less than or equal to 0.4 mm.

[0035] Optionally, when the diameter of the composite welding strip is 0.07~0.2mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 65~75MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 70~80MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 72~82MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 75~85MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 80~90MPa.

[0036] Optionally, when the diameter of the composite welding strip is 0.2~0.3mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 50~60MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 55~65MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 58~68MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 60~70MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 65~75MPa.

[0037] Optionally, when the diameter of the composite welding strip is 0.3~0.4mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 50~60MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 55~65MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 58~68MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 60~70MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 65~75MPa.

[0038] Optionally, the composite welding strip is a triangular welding strip, and the diameter length of the circumscribed circle of the composite welding strip is greater than or equal to 0.07 mm and less than or equal to 0.4 mm.

[0039] Optionally, a ratio of the thickness of the first conductive layer to the thickness of the second conductive layer is greater than or equal to 5 and less than or equal to 9.

[0040] Optionally, the thickness of the second conductive layer is 0.01-0.05 mm.

[0041] Optionally, the composite welding ribbon includes a plurality of free portions and a plurality of second connecting portions connected between the plurality of free portions, the second connecting portions are connected to the back-contact solar cells, and the free portions are separated from the back-contact solar cells.

[0042] Optionally, a maximum spacing distance between the free portion and the back contact solar cell is 0.1-0.4 mm.

[0043] In a second aspect, a photovoltaic system comprises the above-mentioned back-contact solar cell module. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the structure of the first composite welding strip provided in the present application;

[0045] Figure 2 This is a schematic diagram of the structure of the second composite welding strip provided in the present application;

[0046] Figure 3 This is a schematic diagram of the structure of the third composite welding strip provided in the present application;

[0047] Figure 4 This is a schematic diagram of the structure of the fourth composite welding strip provided in the present application;

[0048] Figure 5 This is a schematic diagram of the structure of the fifth composite welding strip provided in the present application;

[0049] Figure 6This is a schematic diagram of the structure of the sixth composite welding strip provided in the present application;

[0050] Figure 7 This is a schematic diagram of the structure of the seventh composite welding strip provided in the present application;

[0051] Figure 8 This is a schematic diagram of the structure of the eighth composite welding strip provided in the present application;

[0052] Figure 9 This is a schematic structural diagram of the first back-contact solar cell module provided in the present application;

[0053] Figure 10 This is a schematic structural diagram of the second back-contact solar cell module provided in the present application.

[0054] Description of reference numerals:

[0055] 100. Composite welding ribbon; 101. First conductive layer; 102. Second conductive layer; 103. First connecting portion; 104. Composite structural layer; 105. Conductive connecting layer; 106. Free portion; 107. Second connecting portion; 108. Connecting layer; 200. Back-contact solar cell. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are merely used to explain the present application and are not intended to limit the present application.

[0057] In the description of this application, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on this application.

[0058] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0059] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0060] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0061] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art will appreciate the application of other processes and / or the use of other materials.

[0062] like Figure 1As shown, in some embodiments, a back-contact solar cell assembly includes a composite welding ribbon 100 and a plurality of back-contact solar cells 200, and the composite welding ribbon 100 is arranged on the backlight surface of the plurality of back-contact solar cells 200. Compared with the double-sided cell structure, the arrangement of the composite welding ribbon 100 on the single side of the back-contact solar cell 200 significantly reduces the degree of bending of the composite welding ribbon 100, so that it is possible for the composite welding ribbon 100 to connect the plurality of back-contact solar cells 200 within a set yield strength range. It should be pointed out that, in this embodiment, the electrical and physical connections between the respective back-contact solar cells 200 and the composite welding ribbon 100 are mainly achieved by welding, but it can be understood that they can also be connected to each other in other ways, which are set according to the needs of use and are not specifically limited here.

[0063] The composite welding strip 100 includes a first conductive layer 101 and a second conductive layer 102. The second conductive layer 102 is arranged on the outer surface of the first conductive layer 101. The first conductive layer 101 includes aluminum elements, and the second conductive layer 102 includes copper elements or nickel elements. In the embodiment of the present application, the metallurgical bonding of the double-layer conductive material between the first conductive layer 101 and the second conductive layer 102 is achieved by electroplating, casting, forging or cold rolling, and the present application is not limited to this. In some embodiments, the material of the second conductive layer 102 includes one or more of nickel, tin, bismuth, silver, copper, aluminum, titanium, lead, indium, and gallium, that is, the material of the second conductive layer 102 can be a single material or a combination or alloy of multiple materials, as long as it can achieve conductivity and facilitate welding, and is not limited to the materials listed in this embodiment. In the embodiment of the present application, the material of the second conductive layer 102 is preferably copper, which has good ductility and good conductivity. The material of the first conductive layer 101 can be aluminum, aluminum alloy, zinc, nickel and other metal materials. Taking into account the functional requirements of conductivity, the first conductive layer 101 is preferably made of aluminum, which has a soft texture, high stability, high corrosion resistance, low cost, and is convenient for subsequent deep processing and compounding.

[0064] The composite welding ribbon 100 has a corresponding yield strength based on its preset dimensions and corresponding composite welding ribbon component ratio C, where the composite welding ribbon component ratio C is the mass ratio of the second conductive layer 102 to the first conductive layer 101 and is greater than or equal to 0.1. In the embodiments of the present application, corresponding yield strengths are set for composite welding ribbons 100 with different preset dimensions and different composite welding ribbon component ratios C. By setting different yield strengths for different types of composite welding ribbons 100, the warping problem that can easily occur after hot pressing annealing of the composite welding ribbon 100 can be better controlled. Furthermore, after extensive research and testing, the researchers concluded that yield strength is the key factor affecting the warping of the composite welding ribbon 100. Based on this understanding, the researchers optimized the applicable range of yield strength for different types of composite welding ribbons 100, ultimately successfully resolving the warping problem of solar cells. This reduces costs while ensuring the applicability and ease of use of the composite welding ribbon 100, facilitating widespread application.

[0065] It can be understood that the present application sets the mass ratio of the second conductive layer 102 to the first conductive layer 101 to be greater than or equal to 0.1. Further, the mass ratio of the second conductive layer 102 to the first conductive layer 101 is set to be greater than or equal to 0.2. Preferably, the mass ratio of the second conductive layer 102 to the first conductive layer 101 is 0.25~2.4. In such an embodiment, the mass ratio of the second conductive layer 102 to the first conductive layer 101 can be 0.25, 0.26, 0.28, 0.3, 0.4, 0.6, 0.8, 1.2, 1.6, 1.8, 2.2, 2.4, or any value between 0.25-2.4, and is not specifically limited here. When the mass ratio of the second conductive layer 102 to the first conductive layer 101 is within this range, on the one hand, the production cost of the composite welding tape 100 can be effectively reduced. On the other hand, in the composite welding tape 100, the bonding strength between the first conductive layer 101 and the second conductive layer 102 is an important consideration. For example, during the cold rolling composite process, when the copper-aluminum thickness ratio decreases (i.e., the aluminum thickness increases relatively), the aluminum strip undergoes more severe plastic deformation, thereby forming more cracks at the interface. These cracks facilitate the entry of more metal compounds and promote interfacial bonding, making the bond between the copper and aluminum strips more secure. When the aluminum layer is too thick, due to the difference in yield stress between copper and aluminum, the time required to reach a common plastic strain becomes longer, which may cause the density of the bonding interface to deteriorate, thereby affecting the bonding strength. Within this range, the bonding strength between the first conductive layer 101 and the second conductive layer 102 is high, and the formed composite welding strip 100 can resist external stress and prevent peeling or falling off between the two layers due to stress.

[0066] Secondly, changes in the mass ratio of the second conductive layer 102 to the first conductive layer 101 also affect the mechanical properties of the composite welding ribbon 100. For example, when the aluminum content is higher, the composite ribbon may exhibit better toughness and ductility; while a higher copper content may improve the conductivity, strength, and hardness of the composite ribbon. When the mass ratio of the second conductive layer 102 to the first conductive layer 101 is within this range, the composite welding ribbon 100 has good ductility and high structural strength, and can achieve stable connections between solar cells.

[0067] In some embodiments, as Figure 9 and Figure 10As shown, the composite welding ribbon 100 has a first connecting portion 103. The angle a formed by the first connecting portion 103 relative to the back-light surface of the back-contact solar cell is greater than or equal to 0° and less than or equal to 60°. The angle a and the yield strength σs of the composite welding ribbon 100 satisfy the following relationship: (90 / 1.63) × cos a ≤ σs ≤ cos a × 90, where a is greater than or equal to 0° and less than or equal to 60°. When using the composite welding ribbon 100 for string soldering between solar cells, the cells are arranged in various configurations. The first connecting portion 103 is provided to achieve high-quality connections between the cells. In some embodiments, multiple back-contact solar cells are arranged at intervals. In this case, the composite welding ribbon 100 can connect multiple back-contact solar cells while maintaining a straight configuration. The angle a formed by the first connecting portion relative to the back-light surface of the back-contact solar cell is greater than or equal to 0° and less than or equal to 20°. Preferably, the angle a formed by the first connecting portion relative to the back-light surface of the back-contact solar cell is greater than or equal to 0° and less than or equal to 10°. Furthermore, the angle a of the first connection portion relative to the backlight surface of the back-contact solar cell is greater than or equal to 0° and less than or equal to 5°. In some embodiments, a plurality of back-contact solar cells are partially overlapped, and the angle a of the first connection portion 103 relative to the back-contact solar cell is greater than or equal to 10° and less than or equal to 60°. Preferably, the angle a of the first connection portion relative to the backlight surface of the back-contact solar cell is greater than or equal to 10° and less than or equal to 45°. Since the cell itself has a certain thickness, the local overlapping area of the back-contact solar cell has a step structure, and the composite welding strip 100 is locally bent when passing through the overlapping area. The bent portion is also the first connection portion 103. The angle of the first connection portion 103 relative to the backlight surface of the back-contact solar cell is determined according to the degree of local bending of the composite welding strip 100 and the thickness of the cell. The present application specially designs the composite welding strip 100 to further ensure that when the composite welding strip 100 is used for series welding between battery cells, the composite welding strip 100 and the battery cell have good adhesion, and the welding is stable and does not deform, especially in the overlapping area between the battery cells. The composite welding strip 100 can achieve a smooth transition connection, which can avoid the occurrence of cold welding and desoldering of the composite welding strip 100 in the overlapping area of the battery cells.

[0068] It is particularly noted that the angle a between the first connecting portion 103 and the back-contact solar cell 200 is the angle formed by the straight line between the two points where the first connecting portion 103 contacts two adjacent back-contact solar cells 200 and the surface of the back-contact solar cell 200, as shown in FIG. Figure 10 shown.

[0069] The yield strength of the composite welding strip 100 can be measured through a tensile test. Specifically, a specimen (in this case, the composite welding strip 100) is placed in a tensile testing machine. Tension is gradually applied while a stress-strain curve is measured and recorded. This curve reflects the relationship between the specimen's deformation and the stress applied during the tensile process. This curve can be used to determine the yield strength of the composite welding strip 100—that is, the stress value at the onset of plastic deformation.

[0070] The present application sets the corresponding yield strength for the composite welding tape 100 based on different sizes and corresponding component ratios, thereby controlling the yield strength of the composite welding tape 100 within a predetermined range, thereby avoiding the problem of the composite welding tape 100 being easily warped and causing warping of the solar cell. The morphology, components and sizes of the composite welding tape 100 can be designed in a diversified manner to meet the process requirements of various types of solar cell modules. Compared with traditional copper welding tapes, the cost is greatly reduced, thereby effectively reducing the production cost of the solar cell modules.

[0071] In some embodiments, the composite welding ribbon 100 includes a composite structural layer 104, formed by combining the first conductive layer 101 and the second conductive layer 102. The composite structural layer 104 is disposed between the first conductive layer 101 and the second conductive layer 102. The composite structural layer 104 is formed by metallurgically bonding the first conductive layer 101 and the second conductive layer 102 together through forging, casting, or other methods. The composite structural layer 104 is an intermetallic compound formed during the metallurgical bonding of the first conductive layer 101 and the second conductive layer 102. The composite structural layer 104 enables a tight bond between the first conductive layer 101 and the second conductive layer 102, allowing for consistent changes when subjected to external stress, without delamination or peeling. Furthermore, the thickness of the composite structural layer 104 is 0 to 30 microns. Preferably, the thickness of the composite structural layer 104 is 15 to 30 microns. In such an embodiment, the thickness of the composite structure layer 104 can be 15 microns, 20 microns, 25 microns, 30 microns, or any value between 15 and 30 microns, without limitation. Within this range, the thickness of the composite structure layer 104 can ensure high bonding strength and peel strength between the first conductive layer 101 and the second conductive layer 102, preventing the two layers from peeling or falling off due to stress.

[0072] Furthermore, the components of the composite structural layer 104 include at least one of Al4Cu9, AlCu, Al2Cu, Al2Cu3, Al3Cu4, and Cu. The formation of intermetallic compounds is key to achieving an effective connection. These compounds can form strong chemical bonds at the connection interface, thereby improving the connection strength. By controlling the process parameters (such as temperature, time, and pressure) during the bonding of the first conductive layer 101 and the second conductive layer 102, the type and amount of the intermetallic compounds can be controlled, thereby optimizing the connection performance. In addition, these intermetallic compounds can further enhance the corrosion resistance of the composite welding strip 100.

[0073] In some embodiments, the composite welding ribbon 100 further includes a conductive connection layer 105 disposed on the surface of the second conductive layer 102. Specifically, the conductive connection layer 105 and the second conductive layer 102 can be metallurgically bonded by hot-dip plating. During the hot-pressing process of the composite welding ribbon 100 and the solar cell, the conductive connection layer 105 melts and then cools, completing the welding process between the composite welding ribbon 100 and the solar cell. Furthermore, the conductive connection layer 105 has a thickness of 1 to 20 microns. Preferably, the conductive connection layer 105 has a thickness of 10 to 15 microns. In such embodiments, the thickness of the conductive connection layer 105 can be 10 microns, 12 microns, 13 microns, 15 microns, or any value in between, without limitation.

[0074] Furthermore, the conductive connection layer 105 comprises at least one of Sn, Bi, and Pb. By adjusting the composition of the conductive connection layer 105, a low-temperature composite welding ribbon 100 or a high-temperature composite welding ribbon 100 can be formed. Specifically, based on a first preset temperature, which is the welding temperature between the composite welding ribbon 100 and the cell, and which ranges from 200°C to 300°C, the low-temperature composite welding ribbon 100 can achieve metal connection at a lower temperature, thereby preventing damage to electronic components or specific materials caused by high temperatures. Specifically, the conductive connection layer 105 comprises Sn, Bi, and Pb; wherein the Bi content is 10% to 40%, the Sn content is 20% to 50%, and the Pb content is 30% to 60%. By controlling the ratio of Sn, Bi, and Pb, the melting point and thermal expansion coefficient of the conductive connection layer 105 can be controlled.

[0075] Based on the second preset temperature, which is the welding temperature between the composite welding ribbon 100 and the solar cell, specifically, the second preset temperature range is 500°C to 600°C. The high-temperature composite welding ribbon 100 can ensure the strength and stability of the welding. Specifically, the conductive connection layer 105 comprises Sn and Pb; wherein the Sn content is 50% to 70%, and the Pb content is 30% to 50%. By controlling the Sn and Pb content ratio, the melting point of the conductive connection layer 105 and the thermal expansion coefficient of the conductive connection layer 105 can be controlled.

[0076] like Figures 1-6 As shown, it should be noted that the conductive connection layer 105 can be arranged on a single side of the composite welding strip 100 facing the back contact battery cell, and the conductive connection layer 105 can also be arranged on both sides of the composite welding strip 100 facing the back contact battery cell and away from the back contact battery cell. The arrangement of the conductive connection layer 105 and the composite welding strip 100 is set according to the production process requirements, and this application does not impose any restrictions.

[0077] In some embodiments, the resistance of the composite welding ribbon 100 is greater than or equal to 60 milliohms and less than or equal to 150 milliohms. When the resistance of the composite welding ribbon 100 is within this range, the series resistance of the module can be significantly reduced, thereby improving the efficiency of current transmission. This means that the solar cell can more efficiently convert light energy into electrical energy, reducing energy loss during the transmission process.

[0078] In some embodiments, the composite welding strip 100 further includes a connecting layer 108, which is disposed between the first conductive layer 101 and the second conductive layer 102. For example, in the electroplating process, since copper plating on aluminum is difficult, the present application provides a connecting layer 108 between the first conductive layer 101 and the second conductive layer 102 to achieve a good bonding between the first conductive layer 101 and the second conductive layer 102. Preferably, the connecting layer 108 includes zinc. Of course, in other embodiments, the connecting layer 108 may also include other materials, which is not limited in the present application.

[0079] In the embodiments of the present application, the composite welding ribbon 100 can have different morphological structures. Based on these different morphological structures, the composite welding ribbon 100 has different dimensional characteristics. For example, the composite welding ribbon 100 is a flat welding ribbon, and the preset dimensions include the width and thickness of the composite welding ribbon 100. Specifically, when the thickness of the composite welding ribbon 100 is 0.1 mm, the width of the composite welding ribbon 100 is less than 2.5 mm; alternatively, when the width of the composite welding ribbon 100 is 2.5 mm, the thickness of the composite welding ribbon 100 is greater than 0.1 mm. This ensures the structural stability and sufficient structural strength of the flat composite welding ribbon 100, thereby achieving a stable connection between the composite welding ribbon 100 and the solar cell.

[0080] like Figures 1-6 As shown, an example based on the composite welding strip 100 being a flat welding strip is as follows:

[0081] In some embodiments, when the width of the composite welding strip 100 is 0.4~0.8 mm and the thickness of the composite welding strip 100 is 0.2~0.3 mm: the composite welding strip component ratio C is 0.2~0.3, and the yield strength is 50~60 MPa; or, the composite welding strip component ratio C is 0.3~0.8, and the yield strength is 55~65 MPa; or, the composite welding strip component ratio C is 0.8~1.2, and the yield strength is 58~68 MPa; or, the composite welding strip component ratio C is 1.2~2, and the yield strength is 60~70 MPa; or, the composite welding strip component ratio C is 2~3, and the yield strength is 65~75 MPa. The setting of the component ratio can be selected according to the production process and the type of battery cell. In this way, based on the same size and morphology, the composite welding strip 100 sets the corresponding yield strength according to the above-mentioned different component ratios, adaptively adjusts the mechanical properties of the composite welding strip 100, and controls the yield strength of the composite welding strip 100 within a predetermined range, thereby avoiding the problem of battery cell warping caused by deformation of the composite welding strip 100.

[0082] In some embodiments, when the width of the composite welding strip 100 is 0.8~1.4 mm and the thickness of the composite welding strip 100 is 0.12~0.2 mm: the composite welding strip component ratio C is 0.2~0.3, and the yield strength is 55~65 MPa; or, the composite welding strip component ratio C is 0.3~0.8, and the yield strength is 60~70 MPa; or, the composite welding strip component ratio C is 0.8~1.2, and the yield strength is 62~72 MPa; or, the composite welding strip component ratio C is 1.2~2, and the yield strength is 65~75 MPa; or, the composite welding strip component ratio C is 2~3, and the yield strength is 70~80 MPa. The setting of the component ratio can be selected according to the production process and the type of battery cell. In this way, based on the same size and morphology, the composite welding strip 100 sets the corresponding yield strength according to the above-mentioned different component ratios, adaptively adjusts the mechanical properties of the composite welding strip 100, and controls the yield strength of the composite welding strip 100 within a predetermined range, thereby avoiding the problem of battery cell warping caused by deformation of the composite welding strip 100.

[0083] In some embodiments, when the width of the composite welding strip 100 is 1.4~1.8 mm and the thickness of the composite welding strip 100 is 0.1~0.15 mm: the composite welding strip component ratio C is 0.2~0.3, and the yield strength is 55~65 MPa; or, the composite welding strip component ratio C is 0.3~0.8, and the yield strength is 60~70 MPa; or, the composite welding strip component ratio C is 0.8~1.2, and the yield strength is 62~72 MPa; or, the composite welding strip component ratio C is 1.2~2, and the yield strength is 65~75 MPa; or, the composite welding strip component ratio C is 2~3, and the yield strength is 70~80 MPa. The setting of the component ratio can be selected according to the production process and the type of battery cell. In this way, based on the same size and morphology, the composite welding strip 100 sets the corresponding yield strength according to the above-mentioned different component ratios, adaptively adjusts the mechanical properties of the composite welding strip 100, and controls the yield strength of the composite welding strip 100 within a predetermined range, thereby avoiding the problem of battery cell warping caused by deformation of the composite welding strip 100.

[0084] In some embodiments, when the width of the composite welding strip 100 is 1.8~2.2 mm and the thickness of the composite welding strip 100 is 0.12~0.2 mm: the composite welding strip component ratio C is 0.2~0.3, and the yield strength is 50~60 MPa; or, the composite welding strip component ratio C is 0.3~0.8, and the yield strength is 55~65 MPa; or, the composite welding strip component ratio C is 0.8~1.2, and the yield strength is 60~70 MPa; or, the composite welding strip component ratio C is 1.2~2, and the yield strength is 62~72 MPa; or, the composite welding strip component ratio C is 2~3, and the yield strength is 65~75 MPa. The setting of the component ratio can be selected according to the production process and the type of battery cell. In this way, based on the same size and morphology, the composite welding strip 100 sets the corresponding yield strength according to the above-mentioned different component ratios, adaptively adjusts the mechanical properties of the composite welding strip 100, and controls the yield strength of the composite welding strip 100 within a predetermined range, thereby avoiding the problem of battery cell warping caused by deformation of the composite welding strip 100.

[0085] In some embodiments, when the width of the composite welding strip 100 is 1.8~2.2 mm and the thickness of the composite welding strip 100 is 0.05~0.12 mm: the composite welding strip component ratio C is 0.2~0.3, and the yield strength is 50~60 MPa; or, the composite welding strip component ratio C is 0.3~0.8, and the yield strength is 55~65 MPa; or, the composite welding strip component ratio C is 0.8~1.2, and the yield strength is 60~70 MPa; or, the composite welding strip component ratio C is 1.2~2, and the yield strength is 62~72 MPa; or, the composite welding strip component ratio C is 2~3, and the yield strength is 65~75 MPa. The setting of the component ratio can be selected according to the production process and the type of battery cell. In this way, based on the same size and morphology, the composite welding strip 100 sets the corresponding yield strength according to the above-mentioned different component ratios, adaptively adjusts the mechanical properties of the composite welding strip 100, and controls the yield strength of the composite welding strip 100 within a predetermined range, thereby avoiding the problem of battery cell warping caused by deformation of the composite welding strip 100.

[0086] In some embodiments, when the width of the composite welding strip 100 is 2.2~2.8 mm and the thickness of the composite welding strip 100 is 0.12~0.2 mm: the composite welding strip component ratio C is 0.2~0.3, and the yield strength is 50~60 MPa; or, the composite welding strip component ratio C is 0.3~0.8, and the yield strength is 55~65 MPa; or, the composite welding strip component ratio C is 0.8~1.2, and the yield strength is 60~70 MPa; or, the composite welding strip component ratio C is 1.2~2, and the yield strength is 62~72 MPa; or, the composite welding strip component ratio C is 2~3, and the yield strength is 65~75 MPa. The setting of the component ratio can be selected according to the production process and the type of battery cell. In this way, based on the same size and morphology, the composite welding strip 100 sets the corresponding yield strength according to the above-mentioned different component ratios, adaptively adjusts the mechanical properties of the composite welding strip 100, and controls the yield strength of the composite welding strip 100 within a predetermined range, thereby avoiding the problem of battery cell warping caused by deformation of the composite welding strip 100.

[0087] like Figure 7 As shown, in some embodiments, the composite welding ribbon 100 is a round wire welding ribbon, and the diameter of the composite welding ribbon 100 is greater than or equal to 0.07 mm and less than or equal to 0.4 mm. Within this diameter range, the composite welding ribbon 100 can provide a sufficient welding area to ensure the strength and stability of the welding.

[0088] An example based on the composite welding strip 100 being a round wire welding strip is as follows;

[0089] In some embodiments, when the diameter of the composite welding ribbon 100 is 0.07-0.2 mm, the composite welding ribbon component ratio C is 0.2-0.3, and the yield strength is 65-75 MPa; alternatively, the composite welding ribbon component ratio C is 0.3-0.8, and the yield strength is 70-80 MPa; alternatively, the composite welding ribbon component ratio C is 0.8-1.2, and the yield strength is 72-82 MPa; alternatively, the composite welding ribbon component ratio C is 1.2-2, and the yield strength is 75-85 MPa; alternatively, the composite welding ribbon component ratio C is 2-3, and the yield strength is 80-90 MPa. The component ratio setting can be selected based on the production process and the type of solar cell. Thus, based on the same size and morphology, the composite welding ribbon 100 can be configured with corresponding yield strengths according to the above different component ratios, adaptively adjusting the mechanical properties of the composite welding ribbon 100 and controlling the yield strength of the composite welding ribbon 100 within a predetermined range, thereby preventing the problem of solar cell warping caused by deformation of the composite welding ribbon 100.

[0090] In some embodiments, when the diameter of the composite welding ribbon 100 is 0.2-0.3 mm, the composite welding ribbon component ratio C is 0.2-0.3, and the yield strength is 50-60 MPa; alternatively, the composite welding ribbon component ratio C is 0.3-0.8, and the yield strength is 55-65 MPa; alternatively, the composite welding ribbon component ratio C is 0.8-1.2, and the yield strength is 58-68 MPa; alternatively, the composite welding ribbon component ratio C is 1.2-2, and the yield strength is 60-70 MPa; alternatively, the composite welding ribbon component ratio C is 2-3, and the yield strength is 65-75 MPa. The component ratio setting can be selected based on the production process and the type of solar cell. Thus, based on the same size and morphology, the composite welding ribbon 100 can be configured with corresponding yield strengths according to the above different component ratios, adaptively adjusting the mechanical properties of the composite welding ribbon 100 and controlling the yield strength of the composite welding ribbon 100 within a predetermined range, thereby preventing the problem of solar cell warping caused by deformation of the composite welding ribbon 100.

[0091] In some embodiments, when the diameter of the composite welding ribbon 100 is 0.3-0.4 mm, the composite welding ribbon component ratio C is 0.2-0.3, and the yield strength is 50-60 MPa; alternatively, the composite welding ribbon component ratio C is 0.3-0.8, and the yield strength is 55-65 MPa; alternatively, the composite welding ribbon component ratio C is 0.8-1.2, and the yield strength is 58-68 MPa; alternatively, the composite welding ribbon component ratio C is 1.2-2, and the yield strength is 60-70 MPa; alternatively, the composite welding ribbon component ratio C is 2-3, and the yield strength is 65-75 MPa. The component ratio setting can be selected based on the production process and the type of solar cell. Thus, based on the same size and morphology, the composite welding ribbon 100 can be configured with corresponding yield strengths according to the above different component ratios, adaptively adjusting the mechanical properties of the composite welding ribbon 100 and controlling the yield strength of the composite welding ribbon 100 within a predetermined range, thereby preventing the problem of solar cell warping caused by deformation of the composite welding ribbon 100.

[0092] like Figure 8 As shown, in some embodiments, the composite welding strip 100 is a triangular welding strip, and the diameter of the circumscribed circle of the composite welding strip 100 is greater than or equal to 0.07 mm and less than or equal to 0.4 mm. Within this size range, the composite welding strip 100 can provide a sufficient welding area to ensure the strength and stability of the welding.

[0093] In some embodiments, the ratio of the thickness of the first conductive layer 101 to the thickness of the second conductive layer 102 is greater than or equal to 5 and less than or equal to 9. For example, the ratio of the thickness of the first conductive layer 101 to the thickness of the second conductive layer 102 can be 5, 6, 7, 8, 9, or any value between 5 and 9, without limitation. Within this ratio range, when subjected to external forces or environmental factors (such as temperature or humidity changes), the thicker first conductive layer 101 can better resist deformation, thereby maintaining the integrity and performance of the first conductive layer 101. Although the second conductive layer 102 is thinner, the composite welding ribbon 100 formed by combining with the thicker first conductive layer 101 can avoid warping and form a more continuous and stable conductive path, thereby improving conductive efficiency. Preferably, the thickness of the second conductive layer 102 is 0.01 to 0.05 mm. For example, for example, 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, or any value between 0.01 mm and 0.05 mm, which is not specifically limited here.

[0094] The thickness of the first conductive layer 101 and the second conductive layer 102 mentioned in this application refers to the average thickness of the first conductive layer 101 and the second conductive layer 102 film layers.

[0095] like Figure 3As shown, in some embodiments, the first conductive layer 101 has a first surface and a second surface disposed opposite each other in the thickness direction, with a second conductive layer 102 disposed on each of the first and second surfaces. The second conductive layer 102 covering the first surface has a first thickness, while the second conductive layer 102 covering the second surface has a second thickness. The first surface is disposed toward the cell, while the second surface is disposed away from the cell. Optionally, the second thickness is greater than the first thickness. This structural design can further stabilize the connection between the composite welding ribbon 100 and the cell, reducing deformation caused by ambient temperature fluctuations.

[0096] This application is attached Figures 1-8 The structures of the composite welding strip 100 in the embodiment are only several typical embodiments designed in this application, and the structures of the composite welding strip 100 in this application are not limited to these several embodiments.

[0097] like Figure 9 As shown, the composite welding ribbon 100 includes a plurality of free portions 106 and a plurality of second connection portions 107 connected between the plurality of free portions 106. The second connection portions 107 are connected to the solar cell, and the free portions 106 are separated from the solar cell. Furthermore, in one embodiment of the present application, the free portions 106 are a deformation buffer structure, and the composite welding ribbon 100 is connected to the back-contact solar cell 200 through each of its second connection portions 107. The specific manufacturing process is to spot weld each second connection portion 107 of a composite welding ribbon 100 to each welding point on a main grid of the back-contact solar cell 200, and each free portion 106 is separated from the back-contact solar cell 200 to form a deformation buffer structure, wherein the deformation buffer structure is various curved shapes such as arc, S-shape, rectangle, or broken line. It should be noted that each of the second connecting portions 107 is located at the same horizontal plane, allowing each second connecting portion 107 to contact the solder joints of the back-contact solar cell 200. The free portions 106 are bent and deformed to extend beyond the second connecting portions 107 at different horizontal planes. Furthermore, the maximum separation distance between the free portions 106 and the solar cell is 0.1-0.4 mm. This allows the composite solder ribbon 100 to have sufficient cushioning margin compared to its conventional straight state to accommodate contraction or expansion.

[0098] Therefore, after the second connecting portions 107 of the composite welding ribbon 100 are welded to the solder joints of the back-contact solar cell 200, the free portion 106 provides a certain buffer between adjacent solder joints. This allows the composite welding ribbon 100 to compensate for the greater amount of shrinkage it experiences after returning to room temperature due to the difference in thermal expansion coefficient between the composite welding ribbon 100 and the back-contact solar cell 200. This reduces stress caused by thermal expansion and contraction, thereby minimizing warping of the back-contact solar cell 200 caused by welding. This allows the back-contact solar cell 200 to be straighter after welding than with conventional methods. Furthermore, the contracted composite welding ribbon 100 can reduce the protruding height of the free portion 106, further flattening the composite welding ribbon 100 after deformation compensation, thereby achieving low warpage for the entire back-contact solar cell 200 assembly.

[0099] In some embodiments, multiple back-contact solar cells 200 are partially overlapped to form an overlapping region, and the first connection portion 103 of the composite welding ribbon 100 is disposed in the overlapping region. This ensures that when the composite welding ribbon 100 is used for string soldering between cells, the composite welding ribbon 100 and the cells are well bonded, and the welding is stable and deformation-free. In particular, in the overlapping region of the cells, the composite welding ribbon 100 can achieve a smooth transition connection, thereby preventing cold solder joints or desoldering of the composite welding ribbon 100 in the overlapping region of the cells.

[0100] A photovoltaic system, comprising the above-mentioned battery assembly. In this embodiment, the photovoltaic system can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water-surface power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it is understandable that the application scenarios of the photovoltaic system are not limited to this, that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple battery assemblies. For example, multiple battery assemblies can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box, which can combine the current generated by the photovoltaic array. The combined current flows through the inverter to be converted into the alternating current required by the mains power grid and then connected to the mains power network to achieve solar power supply.

[0101] Throughout this specification, reference to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0102] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A back contact solar cell module, characterized in that: The invention comprises a composite welding tape and a plurality of back-contact solar cells, wherein the composite welding tape is arranged on the back-light surface of the plurality of back-contact solar cells, the composite welding tape comprises a first conductive layer; a second conductive layer, wherein the second conductive layer is arranged on the outer surface of the first conductive layer, the first conductive layer comprises aluminum, and the second conductive layer comprises copper or nickel; the mass ratio of the second conductive layer to the first conductive layer of the composite welding tape is the composite welding tape component ratio C, and the composite welding tape component ratio C is greater than or equal to 0.1; the composite welding tape has a first connecting portion, the first connecting portion is arranged between two adjacent back-contact solar cells, an angle a of the first connecting portion relative to the back-light surface of the back-contact solar cell is greater than 0° and less than or equal to 60°, the angle a is the angle formed by a straight line between two points of contact between the first connecting portion and the two adjacent back-contact solar cells and the back-light surface of the back-contact solar cell, and the angle a and the yield strength σs of the composite welding tape satisfy the following relationship: (90 / 1.63) ×cos a≤σs≤cos a × 90, Wherein, a is greater than 0° and less than or equal to 60°.

2. The back contact solar cell module according to claim 1, wherein: The plurality of back-contact solar cells are arranged at intervals, and an angle a formed between the first connecting portion and the backlight surface of the back-contact solar cell is greater than 0° and less than or equal to 20°.

3. The back contact solar cell module according to claim 2, wherein: An included angle a formed between the first connecting portion and the backlight surface of the back-contact solar cell is greater than 0° and less than or equal to 10°.

4. The back contact solar cell module according to claim 3, wherein: An included angle a formed between the first connecting portion and the backlight surface of the back-contact solar cell is greater than 0° and less than or equal to 5°.

5. The back contact solar cell module according to claim 1, wherein: The plurality of back-contact solar cells are partially overlapped, and an included angle a of the first connecting portion relative to the backlight surface of the back-contact solar cell is greater than or equal to 10° and less than or equal to 60°.

6. The back contact solar cell module according to claim 5, wherein: An included angle a formed between the first connecting portion and the backlight surface of the back-contact solar cell is greater than or equal to 10° and less than or equal to 45°.

7. The back contact solar cell module according to claim 1, wherein: The component ratio C of the composite welding strip is greater than or equal to 0.

2.

8. The back contact solar cell module according to claim 1, wherein: The component ratio C of the composite welding strip ranges from 0.25 to 2.

4.

9. The back contact solar cell module according to claim 1, wherein: The composite welding tape further includes a composite structural layer, which is formed by combining the first conductive layer and the second conductive layer, and is disposed between the first conductive layer and the second conductive layer.

10. The back contact solar cell module according to claim 9, wherein: The thickness of the composite structure layer is 0-30 microns.

11. The back contact solar cell module according to claim 9, wherein: Components of the composite structural layer include at least one of Al4 Cu9, AlCu, Al2Cu, Al2Cu3, Al3Cu4 and Cu.

12. The back contact solar cell module according to claim 1, wherein: The composite welding tape further includes a conductive connecting layer, which is arranged on the surface of the second conductive layer.

13. The back contact solar cell module according to claim 12, wherein: The thickness of the conductive connection layer is 1 to 20 microns.

14. The back contact solar cell module according to claim 12, wherein: The conductive connection layer comprises at least one of Sn, Bi, and Pb.

15. The back contact solar cell module according to claim 14, wherein: Based on the first preset temperature, the components of the conductive connection layer include Sn, Bi, and Pb; wherein the content of Bi is 10% to 40%, the content of Sn is 20% to 50%, and the content of Pb is 30% to 60%.

16. The back contact solar cell module according to claim 14, wherein: Based on the second preset temperature, the components of the conductive connection layer include Sn and Pb; wherein the content of Sn is 50% to 70%, and the content of Pb is 30% to 50%.

17. The back contact solar cell module according to claim 1, wherein: The resistance of the composite welding strip is greater than or equal to 60 milliohms and less than or equal to 150 milliohms.

18. The back contact solar cell module according to claim 1, wherein: The method further includes a connecting layer, wherein the connecting layer is disposed between the first conductive layer and the second conductive layer.

19. The back contact solar cell module according to claim 18, wherein: The tie layer includes zinc.

20. The back contact solar cell module according to claim 1, wherein The composite welding strip is a flat welding strip.

21. The back contact solar cell module according to claim 20, wherein: When the thickness of the composite welding strip is 0.1 mm, the width of the composite welding strip is less than 2.5 mm; or, when the width of the composite welding strip is 2.5 mm, the thickness of the composite welding strip is greater than 0.1 mm.

22. The back contact solar cell module according to claim 20, wherein: When the width of the composite welding strip is 0.4~0.8mm and the thickness of the composite welding strip is 0.2~0.3mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 50~60MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 55~65MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 58~68MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 60~70MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 65~75MPa.

23. The back contact solar cell module according to claim 20, wherein: When the width of the composite welding strip is 0.8~1.4mm and the thickness of the composite welding strip is 0.12~0.2mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 55~65MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 60~70MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 62~72MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 65~75MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 70~80MPa.

24. The back contact solar cell module according to claim 20, wherein: When the width of the composite welding strip is 1.4~1.8mm and the thickness of the composite welding strip is 0.1~0.15mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 55~65MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 60~70MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 62~72MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 65~75MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 70~80MPa.

25. The back contact solar cell module according to claim 20, wherein: When the width of the composite welding strip is 1.8~2.2mm and the thickness of the composite welding strip is 0.12~0.2mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 50~60MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 55~65MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 60~70MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 62~72MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 65~75MPa.

26. The back contact solar cell module according to claim 20, wherein: When the width of the composite welding strip is 1.8~2.2mm and the thickness of the composite welding strip is 0.05~0.12mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 50~60MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 55~65MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 60~70MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 62~72MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 65~75MPa.

27. The back contact solar cell module according to claim 20, wherein: When the width of the composite welding strip is 2.2~2.8mm and the thickness of the composite welding strip is 0.12~0.2mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 50~60MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 55~65MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 60~70MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 62~72MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 65~75MPa.

28. The back contact solar cell module according to claim 1, wherein: The composite welding strip is a round wire welding strip, and the diameter of the composite welding strip is greater than or equal to 0.07 mm and less than or equal to 0.4 mm.

29. The back contact solar cell module according to claim 28, wherein When the diameter of the composite welding strip is 0.07~0.2mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 65~75MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 70~80MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 72~82MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 75~85MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 80~90MPa.

30. The back contact solar cell module according to claim 28, wherein When the diameter of the composite welding strip is 0.2~0.3mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 50~60MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 55~65MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 58~68MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 60~70MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 65~75MPa.

31. The back contact solar cell module according to claim 28, wherein When the diameter of the composite welding strip is 0.3~0.4mm: the component ratio C of the composite welding strip is 0.2~0.3, and the yield strength is 50~60MPa; or, the component ratio C of the composite welding strip is 0.3~0.8, and the yield strength is 55~65MPa; or, the component ratio C of the composite welding strip is 0.8~1.2, and the yield strength is 58~68MPa; or, the component ratio C of the composite welding strip is 1.2~2, and the yield strength is 60~70MPa; or, the component ratio C of the composite welding strip is 2~3, and the yield strength is 65~75MPa.

32. The back contact solar cell module according to claim 1, wherein: The composite welding strip is a triangular welding strip, and the diameter length of the circumscribed circle of the composite welding strip is greater than or equal to 0.07 mm and less than or equal to 0.4 mm.

33. The back contact solar cell module according to claim 1, wherein: The ratio of the thickness of the first conductive layer to the thickness of the second conductive layer is greater than or equal to 5 and less than or equal to 9.

34. The back contact solar cell module according to claim 1, wherein: The thickness of the second conductive layer is 0.01-0.05 mm.

35. The back contact solar cell module according to claim 1, wherein The composite welding strip includes a plurality of free portions and a plurality of second connection portions connected between the plurality of free portions, the second connection portions are connected to the back contact solar cells, and the free portions are separated from the back contact solar cells.

36. The back contact solar cell module according to claim 35, wherein The maximum spacing distance between the free portion and the back contact solar cell is 0.1-0.4 mm.

37. A photovoltaic system, characterized in that: The photovoltaic system includes the back-contact solar cell assembly according to any one of claims 1 to 36.

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