A solder strip and photovoltaic module

Abstract

This application relates to the field of photovoltaic technology, and more particularly to a solder ribbon and a photovoltaic module. The solder ribbon includes an inner core and an outer shell. The inner core includes multiple continuously arranged curved segments, and the outer shell wraps around the outside of the inner core. The curvature of the solder ribbon is less than the minimum curvature of the curved segments. In this application, the thermal expansion coefficients of the solar cell and the solder ribbon are different. When the external temperature changes, the curved segments can extend or retract to compensate for the difference in size between the solar cell and the solder ribbon, preventing the solder ribbon from being subjected to excessive pulling force and detaching from the pads. This would prevent the photocurrent generated by the solar cell from being effectively discharged, affecting the photoelectric conversion efficiency of the solar cell. The outer shell can protect the inner core, isolating it from contact with air and moisture, and reducing the curvature of the solder ribbon. This results in a larger contact area between the solder ribbon and the pads, stronger connection between the solder ribbon and the pads, and makes it less likely to detach from the pads.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and more particularly to a solder strip and a photovoltaic module. Background Technology

[0002] A photovoltaic module consists of solar cells and solder ribbons. Solder pads are provided on the solar cells, and solder ribbons connect to the solar cells via these pads. One solder ribbon connects to two adjacent solar cells to conduct the photocurrent generated by the solar cells for human use.

[0003] Because the thermal expansion coefficients of the solder ribbon and the solar cell are different, the difference in size changes between the solar cell and the solder ribbon when the external temperature changes causes a large pulling force at the connection point between the solder ribbon and the pad. This makes the solder ribbon easy to detach from the pad, resulting in the inability to effectively conduct the photocurrent, which in turn affects the photoelectric conversion efficiency of the photovoltaic module. Summary of the Invention

[0004] This application provides a solder ribbon and a photovoltaic module to solve the technical problem that the solder ribbon is prone to falling off the solar cell when the external temperature changes.

[0005] This application provides a welding strip comprising an inner core and an outer shell. The inner core includes a plurality of continuously arranged curved segments, and the outer shell wraps around the outside of the inner core. The curvature of the welding strip is less than the minimum curvature of the curved segments.

[0006] In one possible design, the diameter of the solder strip remains constant along its extension direction.

[0007] In one possible design, the solder strip extends in a straight line.

[0008] In one possible design, the cross-sectional shape of the solder strip is circular, elliptical, triangular, or rectangular.

[0009] In one possible design, the diameter d1 of the inner core satisfies: 100μm≤d1≤400μm; and / or, the diameter d2 of the solder strip satisfies: 105μm≤d2≤500μm.

[0010] In one possible design, the minimum distance d3 between the outer peripheral surface of the inner core and the outer peripheral surface of the outer shell satisfies: 5μm≤d3≤100μm.

[0011] In one possible design, the length L of the bent section along the extension direction of the weld strip satisfies: 1mm ≤ L ≤ 20mm.

[0012] In one possible design, the inner core is a copper wire and the outer shell is a tin layer.

[0013] This application provides a photovoltaic module including solar cells and the aforementioned solder strips, wherein the solder strips connect adjacent solar cells.

[0014] In one possible design, the curved segment includes a first curved segment and a second curved segment, the first curved segment being connected to the battery cell and the second curved segment not being connected to the battery cell; the second curved segment is located between adjacent first curved segments.

[0015] In one possible design, the number n of the second bending segments between adjacent first bending segments satisfies: 1 ≤ n ≤ 20.

[0016] In one possible design, the curvature of the first curved segment is less than the curvature of the second curved segment.

[0017] In this application, the thermal expansion coefficients of the solar cell and the solder ribbon are different. By making the inner core have multiple curved sections, the curved sections can extend or retract when the external temperature changes to compensate for the difference in size between the solar cell and the solder ribbon. This prevents the solder ribbon from being subjected to excessive pulling force and falling off the solder pad, which would cause the photocurrent generated by the solar cell to be unable to be effectively discharged, thus affecting the photoelectric conversion efficiency of the solar cell.

[0018] The outer shell, encasing the inner core, protects it by isolating it from air and moisture. It also ensures the curvature of the solder ribbon is less than the minimum curvature of the bent section, meaning the degree of curvature of the solder ribbon is less than that of the bent section. This less curvature results in a larger contact area between the solder ribbon and the pad, leading to a stronger bond and reducing the likelihood of detachment. Furthermore, the less curvature facilitates soldering the ribbon to the pad, simplifying the connection between the ribbon and the cell. Additionally, during lamination, the curved solder ribbon and bent section release stress caused by the inconsistent thermal stress between the ribbon and the cell, reducing cell warping and consequently decreasing the probability of cell fragmentation or breakage.

[0019] 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

[0020] Figure 1 This is a schematic diagram of the structure of the photovoltaic module provided in this application in one embodiment;

[0021] Figure 2 for Figure 1 A schematic diagram of the structure of the battery cells and solder strips in the diagram;

[0022] Figure 3 This is a schematic diagram of the structure of the photovoltaic module provided in this application in another embodiment, wherein the solar cell is a back-contact cell;

[0023] Figure 4 This is a schematic diagram of the structure of the photovoltaic module provided in this application in another embodiment, wherein the solar cell is a back-contact tandem cell;

[0024] Figure 5 for Figure 3 , Figure 4 A schematic diagram of the structure of the battery cells and solder strips in the diagram;

[0025] Figure 6 for Figure 1 A schematic diagram of the structure of the battery cell in one embodiment;

[0026] Figure 7 for Figure 1 A schematic diagram of the structure of the battery cell in another embodiment;

[0027] Figure 8 This is a schematic diagram of the structure of the solder strip provided in this application in one embodiment;

[0028] Figure 9 A schematic diagram of the structure of the solder strip provided in this application in another embodiment;

[0029] Figure 10 for Figure 9 solder strips and Figure 6 A schematic diagram of the structure of the battery cells.

[0030] Figure label:

[0031] 1- Welding strip;

[0032] 11-Inner core;

[0033] 11a - First bending segment;

[0034] 11b - Second bending segment;

[0035] 12-Outer shell;

[0036] 2-Battery Cells;

[0037] 21 - First grid line;

[0038] 22 - Second grid line;

[0039] 23 - Pads;

[0040] 3- Front-side packaging structure;

[0041] 4-Front-side film layer;

[0042] 5-Backside film layer;

[0043] 6- Rear packaging structure.

[0044] 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

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0049] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0050] This application provides a photovoltaic module, which includes solar cells 2 and solder ribbons 1. The solder ribbons 1 connect adjacent solar cells 2 to form a cell string. The solar cells 2 have a front side and a back side opposite to each other along their thickness direction Z. The front side is the light-receiving surface of the solar cell 2, and the back side is the light-receiving surface of the solar cell 2.

[0051] Figure 1 This is a schematic diagram of the structure of the photovoltaic module provided in this application in one embodiment. Figure 2 for Figure 1 A schematic diagram of the structure of the battery cell 2 and the solder ribbon 1. (See attached diagram.) Figure 1 and Figure 2As shown, for solar cells 2 with positive and negative grid lines located on the front and back sides respectively, such as Passivated Emitter Rear Cell (PERC), Tunnel Oxide Passivated Contact (TOPCON), Heterojunction with Intrinsic Thin-layer (HIT), and Perovskite Solar Cells (PSC), the solder ribbon 1 extends from the front side of one solar cell 2 to the back side of another solar cell 2 or from the back side of one solar cell 2 to the front side of another solar cell 2 to achieve the connection of adjacent solar cells 2.

[0052] For PERC cells, along their thickness direction, the PERC cell sequentially includes a front surface silver electrode, a front surface silicon nitride passivation layer, a phosphorus emitter layer, a P-type substrate silicon layer, a local aluminum back field, a metallic aluminum back electrode, and a back passivation layer (Al2O3 / SiN). x PERC cells use a passivation film to passivate the back surface, replacing the all-aluminum back surface, which enhances light reflection on the silicon substrate and reduces the recombination rate on the back surface, thus improving the photoelectric conversion efficiency of the cell by 0.5%-1%.

[0053] For a TOPCon cell, along its thickness direction, it sequentially comprises a silver electrode, a front-surface silicon nitride passivation layer, a boron-doped emitter, an N-type substrate silicon layer, a diffused doped layer, an ultrathin silicon oxide layer, doped polycrystalline silicon, silicon nitride, and the silver electrode. The back of the cell consists of an ultrathin silicon oxide layer (1nm~2nm) and a phosphorus-doped microcrystalline amorphous mixed Si film, which together form a passivation contact structure. This structure blocks minority carrier recombination, increasing the cell's open-circuit voltage and short-circuit current. The ultrathin oxide layer allows majority carrier electrons to tunnel into the polycrystalline silicon layer while simultaneously blocking minority carrier recombination. The excellent passivation effect of the ultrathin silicon oxide and heavily doped silicon film causes band bending on the silicon wafer surface, creating a field passivation effect. This significantly increases the probability of electron tunneling, reduces contact resistance, and improves the cell's open-circuit voltage and short-circuit current, thereby enhancing the cell's photoelectric conversion efficiency.

[0054] For HIT cells, along their thickness direction, HIT cells sequentially include a front low-temperature silver electrode, a front conductive film, an N-type amorphous silicon film, an intrinsic amorphous silicon film, an N-type substrate silicon layer, an intrinsic amorphous silicon film, a P-type amorphous silicon film, a back conductive film, and a back low-temperature silver electrode.

[0055] For a perovskite solar cell, along its thickness direction, the perovskite solar cell sequentially includes a substrate material, a conductive thin film, an electron transport layer (titanium dioxide), a perovskite absorption layer (hole transport layer), and a metal cathode. Perovskite materials have a high light absorption coefficient and a long carrier diffusion distance. After the photons absorbed by the perovskite material are converted into electrons, they are easily collected by the electrodes with minimal loss, thus generating high photogenerated voltage and current, resulting in high photoelectric conversion efficiency.

[0056] Figure 3 This is a schematic diagram of the structure of the photovoltaic module provided in this application in another embodiment, wherein the solar cell 2 is a back contact cell. Figure 4 This is a schematic diagram of the structure of the photovoltaic module provided in this application in another embodiment, wherein the solar cell 2 is a back-contact tandem solar cell. Figure 5 for Figure 3 , Figure 4 A schematic diagram of the structure of the battery cell 2 and the solder ribbon 1. (See attached diagram.) Figures 3-5 As shown, for a battery cell 2 where both the positive and negative grid lines are located on the back side, such as a back contact battery (BC) or a back contact stacked battery, the solder ribbon 1 extends from the back side of one battery cell 2 to the back side of another battery cell 2 to achieve the connection between adjacent battery cells 2.

[0057] For BC cells, the emitter, surface field, and metal electrodes are all located on the back of the cell and arranged in an interdigitated pattern. The front side of cell 2 uses SiN. x / SiO x The double-layer anti-reflection passivation film ensures that there are no metal electrodes blocking the front of the cell, allowing the cell 2 to receive more incident light, reducing optical losses and improving photoelectric conversion efficiency. BC cells can also be subdivided into interdigitated back contact (IBC), heterojunction back contact (HBC), and tunnel oxide back contact (TBC).

[0058] For a back-contact tandem solar cell, it includes a top cell, an intermediate connecting layer, and a bottom cell, with the intermediate connecting layer connecting the bottom and top cells. The top cell can be one of a perovskite solar cell, a cadmium telluride solar cell, a copper indium gallium selenide solar cell, or a gallium arsenide solar cell. The bottom cell is a BC cell. The intermediate connecting layer can be selected from a transparent material with a high refractive index, such as a transparent conductive metal oxide thin film (ITO). An effective intermediate connecting layer needs to have high light transmittance to reduce light reflection and absorption at the connecting layer interface, as well as good conductivity to reduce the impact of series resistance on device performance.

[0059] like Figure 1 , Figure 3 and Figure 4 As shown, the photovoltaic module also includes: a front encapsulation structure 3, a front film layer 4, a back film layer 5, and a back encapsulation structure 6. The front encapsulation structure 3, the front film layer 4, the back film layer 5, and the back encapsulation structure 6 encapsulate the cell string to ensure that the photovoltaic module has high mechanical strength, reduce the impact of hail, wind, mechanical vibration, etc. on the back-contact photovoltaic module, improve the sealing performance of the back-contact photovoltaic module, and enhance its corrosion resistance and safety.

[0060] Specifically, the front encapsulation structure 3 and the back encapsulation structure 6 can be one of rigid materials such as tempered glass, polyethylene terephthalate (PET), and polycarbonate (PC), or one of flexible materials such as polyvinyl fluoride (PVF), ethylene-tetrafluoroethylene copolymer (ETFE), and polyvinylidene fluoride (PVDF). These materials have high light transmittance, which can improve the photoelectric conversion efficiency of the back-contact photovoltaic module and ensure its power output. The front film layer 4 and the back film layer 5 can be one of the following materials: ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), polyvinyl butyral (PVB), EVA-POE-EVA co-extruded film (EPE), EVA-POE co-extruded film (EP).

[0061] The following is a detailed discussion using a battery cell 2 with the positive and negative grid lines located on the front and back sides, respectively.

[0062] Figure 6 for Figure 1 A schematic diagram of the structure of the battery cell 2 in one embodiment. (See attached diagram.) Figure 6As shown, the solar cell 2 has a first grid line 21 extending along a first direction X and a second grid line 22 extending along a second direction Y. For example, the first grid line 21 is the main grid, and the second grid line 22 is a fine grid. The first grid line 21 is thicker than the second grid line 22, indicating a main grid cell. Multiple first grid lines 21 are spaced apart along the second direction Y, and multiple second grid lines 22 are spaced apart along the first direction X. Each first grid line 21 is connected to multiple second grid lines 22. The photocurrent generated by the solar cell 2 can be collected by the second grid lines 22, and the photocurrent collected by the second grid lines 22 can be collected by the first grid lines 21. A solder pad 23 is provided on the first grid line 21, and a solder ribbon 1 is soldered to the solder pad 23, connecting the solder ribbon 1 to the first grid line 21. The photocurrent in the first grid line 21 can flow through the solder pad 23 to the solder ribbon 1, thereby conducting the current out of the solar cell 2.

[0063] Specifically, multiple pads 23 are arranged at intervals along the first direction X. The pads 23 can contact the second gate line 22 or be located between two second gate lines 22.

[0064] Wherein, the first direction X and the second direction Y are both perpendicular to the thickness direction Z of the battery cell 2. For example, one of the first direction X and the second direction Y is the length direction of the battery cell 2 and the other is the width direction of the battery cell 2. The first direction X and the second direction Y are perpendicular to each other.

[0065] Figure 7 for Figure 1 A schematic diagram of the structure of battery cell 2 in another embodiment. (See attached diagram.) Figure 7 As shown, the solar cell 2 only has a second grid line 22 extending along the second direction Y, that is, the solar cell 2 does not have a first grid line 21, i.e., it is a cell without a main grid. The pad 23 is provided on the second grid line 22, so that the solder ribbon 1 can be directly connected to the second grid line 22. The photocurrent collected by the second grid line 22 can flow directly to the solder ribbon 1 through the pad 23, thereby conducting the current from the solar cell 2.

[0066] Figure 8 This is a schematic diagram of the structure of the solder strip 1 provided in this application in one embodiment. Figure 8 As shown, the welding strip 1 includes an inner core 11 and an outer shell 12. The inner core 11 includes a plurality of continuously arranged curved segments. The outer shell 12 wraps around the outside of the inner core 11. The curvature of the welding strip 1 is less than the minimum curvature of the curved segments.

[0067] When the external temperature changes, the photovoltaic module also follows the physical law of thermal expansion and contraction. The thermal expansion coefficient of the cell 2 is different from that of the solder ribbon 1. By making the inner core 11 have multiple bending sections, the bending sections can extend or retract when the external temperature changes to compensate for the difference in size between the cell 2 and the solder ribbon 1. This prevents the solder ribbon 1 from being subjected to excessive pulling force and falling off the solder pad 23, which would cause the photocurrent generated by the cell 2 to be unable to be effectively discharged, thus affecting the photoelectric conversion efficiency of the cell 2.

[0068] The outer shell 12, encasing the inner core 11, protects it by isolating it from air and moisture. It also ensures that the curvature of the solder ribbon 1 is less than the minimum curvature of the bent section, meaning the degree of curvature of the solder ribbon 1 is less than that of the bent section. This less curvature of the solder ribbon 1 results in a larger contact area between it and the pad 23, strengthening the connection and preventing it from detaching from the pad 23. Furthermore, the less curvature of the solder ribbon 1 facilitates its bonding to the pad 23, reducing the difficulty of connecting it to the battery cell 2.

[0069] Furthermore, after the battery cells 2 are connected into a battery string using solder ribbons 1, a front film layer 4 and a front encapsulation structure 3 are formed on the front side of the battery string, and a back film layer 5 and a back encapsulation structure 6 are formed on the back side of the battery string. Then, lamination is performed under specific temperature and pressure conditions, connecting the front encapsulation structure 3, the front film layer 4, the battery string, the back film layer 5, and the back encapsulation structure 6 into a single unit. During the lamination process, the bent solder ribbons 1 and the bent sections can release the stress caused by the inconsistent thermal stress between the solder ribbons 1 and the battery cells 2, reducing the degree of warping of the battery cells 2 and thus reducing the probability of battery cell 2 fragmentation or breakage.

[0070] like Figure 8 As shown, the diameter of the welding strip 1 remains constant along its extension direction, thus ensuring a more uniform force on the battery cell 2 from the welding strip 1. This prevents stress concentration caused by local diameter changes in the welding strip 1, which could lead to fragmentation or breakage of the battery cell 2. Furthermore, a welding strip 1 with a uniform diameter facilitates production, reduces manufacturing costs, and allows for controllable elongation.

[0071] It is understandable that the constant diameter of the solder strip 1 along its extension direction means that the change in the diameter of the solder strip 1 is small and difficult to observe with the naked eye.

[0072] Figure 9 This is a schematic diagram of the structure of the solder strip 1 provided in this application in another embodiment. (See diagram below.) Figure 9 As shown, the solder ribbon 1 extends in a straight line. When the solder ribbon 1 is placed on the battery cell 2, it can contact the solder pad 23, thus facilitating the soldering of the solder ribbon 1 to the solder pad 23. At the same time, the solder ribbon 1, which extends in a straight line, is easy to manufacture and has a lower production cost.

[0073] like Figure 9 As shown, the diameter d1 of the inner core 11 satisfies: 100μm≤d1≤400μm. For example, the diameter d1 of the inner core 11 can be: 100μm, 112μm, 115μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, 270μm, 280μm, 290μm, 300μm, 310μm, 320μm, 330μm, 340μm, 350μm, 360μm, 370μm, 380μm, 390μm, 395μm, 398μm, 400μm, etc.

[0074] The diameter d1 of the inner core 11 should not be too large or too small. If the diameter d1 of the inner core 11 is too large (e.g., greater than 400 μm), the amount of inner core 11 used will increase, and the cost of the solder ribbon 1 will increase. If the diameter of the inner core 11 is too small (e.g., less than 100 μm), the resistance of the solder ribbon 1 will increase, and the conductivity of the solder ribbon 1 will decrease. Therefore, the diameter d1 of the inner core 11 should be selected within a reasonable range.

[0075] like Figure 9 As shown, the diameter d2 of solder strip 1 satisfies: 105μm ≤ d2 ≤ 500μm. For example, the diameter d2 of solder strip 1 can specifically be: 105μm, 106μm, 108μm, 110μm, 115μm, 118μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, 2... 70μm, 280μm, 290μm, 300μm, 310μm, 320μm, 330μm, 340μm, 350μm, 360μm, 370μm, 380μm, 3 90μm, 400μm, 410μm, 420μm, 430μm, 440μm, 450μm, 460μm, 470μm, 480μm, 490μm, 500μm, etc.

[0076] The diameter d2 of the solder ribbon 1 should not be too large or too small. If the diameter d2 of the solder ribbon 1 is too large (e.g., greater than 500 μm), the cost of the solder ribbon 1 will increase, and the area of ​​the solder ribbon 1 blocking the solar cell 2 will increase, affecting the photoelectric conversion efficiency of the solar cell 2. If the diameter d2 of the solder ribbon 1 is too small (e.g., less than 105 μm), the resistance of the solder ribbon 1 will increase, and the conductivity of the solder ribbon 1 will decrease. Therefore, the diameter d2 of the solder ribbon 1 should be selected within a reasonable range.

[0077] like Figure 9 As shown, the minimum distance d3 between the outer peripheral surface of the inner core 11 and the outer peripheral surface of the outer shell 12 satisfies: 5μm≤d3≤100μm. For example, the minimum distance d3 between the outer peripheral surface of the inner core 11 and the outer peripheral surface of the outer shell 12 can be specifically: 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm. , 15μm, 18μm, 20μm, 22μm, 25μm, 28μm, 30μm, 32μm, 35μm, 38μm, 40μm, 42μm, 45μm m, 48μm, 50μm, 52μm, 55μm, 58μm, 60μm, 62μm, 65μm, 68μm, 70μm, 72μm, 75μm, 78 μm, 80μm, 82μm, 85μm, 88μm, 90μm, 92μm, 95μm, 96μm, 97μm, 98μm, 99μm, 100μm, etc.

[0078] The minimum distance d3 between the outer peripheral surface of the inner core 11 and the outer peripheral surface of the outer shell 12 should not be too large or too small. If the minimum distance d3 between the outer peripheral surface of the inner core 11 and the outer peripheral surface of the outer shell 12 is too large (e.g., greater than 100 μm), on the one hand, the diameter d2 of the solder ribbon 1 will be too large, increasing the cost of the solder ribbon 1, and the increased shading area of ​​the solder ribbon 1 on the solar cell 2 will affect the photoelectric conversion efficiency of the solar cell 2. On the other hand, if the minimum distance d3 between the outer peripheral surface of the inner core 11 and the outer peripheral surface of the outer shell 12 is too small (e.g., less than 5 μm), the outer shell 12 will be easily worn at its thinnest point, causing the inner core 11 to be exposed and easily damaged. Therefore, the minimum distance d3 between the outer peripheral surface of the inner core 11 and the outer peripheral surface of the outer shell 12 should be selected within a reasonable range.

[0079] like Figure 9 As shown, along the extension direction of the welding strip 1, the length L of the bent section satisfies: 1mm ≤ L ≤ 20mm. For example, the specific length L of the bent section can be: 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, 10.5mm, 11mm, 11.5mm, 12mm, 12.5mm, 13mm, 13.5mm, 14mm, 14.5mm, 15mm, 15.5mm, 16mm, 16.5mm, 17mm, 17.5mm, 18mm, 18.5mm, 19mm, 19.2mm, 19.5mm, 19.8mm, 20mm, etc.

[0080] Along the extension direction of the solder ribbon 1, the length L of the bending section should not be too large or too small. If the length L of the bending section is too large (e.g., greater than 20 mm), the length of the bending section is greater than the distance between adjacent solder pads 23. When the external temperature changes, the bending section becomes less effective in compensating for the difference in size between the solar cell 2 and the solder ribbon 1, thus failing to effectively prevent the solder ribbon 1 from being subjected to excessive pulling force and falling off from the solder pad 23. This results in the inability to effectively conduct the photocurrent generated by the solar cell 2, affecting the photoelectric conversion efficiency of the solar cell 2. If the length L of the bending section is too small (e.g., less than 1 mm), more cores 11 are needed per unit length of solder ribbon 1, increasing the cost of the solder ribbon 1. Therefore, the length L of the bending section should be selected within a reasonable range.

[0081] In the above embodiment, the inner core 11 is made of copper wire, and the outer shell 12 is made of tin. Copper wire has good conductivity, resulting in less current loss during transmission. Tin layer has good corrosion resistance and solderability, eliminating the need to grind the solder strip 1 before soldering and simplifying the soldering process. Tin layer can also fill the tiny gaps between the copper wire and the solder pad 23, reducing the contact resistance between the solder strip 1 and the solder pad 23. In addition, the melting point of tin layer is lower than that of copper wire, which lowers the temperature required for soldering, making it less likely to damage the battery cell 2 and reducing the cost of soldering. It is understood that the inner core 11 can also be made of other materials with good conductivity, and the outer shell 12 can also be made of other materials with good corrosion resistance and solderability.

[0082] In the above embodiments, the cross-sectional shape of the solder ribbon 1 can be circular, elliptical, triangular, or rectangular. For example, when the cross-sectional shape of the solder ribbon 1 is circular, it has the advantages of a smaller area obstructing the battery cell 2 and ease of production. For example, when the cross-sectional shape of the solder ribbon 1 is rectangular, it has the advantage of being less likely to roll relative to the solder pad 23 before welding, facilitating the fixation of the solder ribbon 1 during welding.

[0083] Figure 10 for Figure 9 solder strip 1 and Figure 6 A schematic diagram of the structure of the battery cell 2. (See diagram below.) Figure 10 As shown, the bending section includes a first bending section 11a and a second bending section 11b. The first bending section 11a is connected to the solar cell 2, while the second bending section 11b is not connected to the solar cell 2. A second bending section 11b is located between adjacent first bending sections 11a. The second bending section 11b enhances the ability of the solder ribbon 1 to compensate for the dimensional differences between the solar cell 2 and the solder ribbon 1, further preventing the solder ribbon 1 from being subjected to excessive pulling force and detaching from the pad 23, thus preventing the photocurrent generated by the solar cell 2 from being effectively discharged and affecting the photoelectric conversion efficiency of the solar cell 2.

[0084] Specifically, between adjacent first curved segments 11a, the number n of second curved segments 11b satisfies: 1≤n≤20.

[0085] For example, the number n of the second bending segments 11b between adjacent first bending segments 11a satisfies: 1≤n≤6, thus applicable to gridless cells with small distances between adjacent pads 23, for example, the number n of the second bending segments 11b is 1, 2, 3, 4, 5, 6.

[0086] For example, the number n of the second bending segments 11b between adjacent first bending segments 11a satisfies: 5≤n≤20, thus applicable to main grid cells with large distances between adjacent pads 23. For example, the number n of the second bending segments 11b is 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20.

[0087] Between adjacent first bending segments 11a, the number n of second bending segments 11b should not be too large or too small. If the number n of second bending segments 11b is too large (e.g., more than 20), the bending degree of the second bending segments 11b is large, resulting in more inner cores 11 required per unit length of solder ribbon 1, and a larger diameter d2 of solder ribbon 1, which in turn increases the cost of solder ribbon 1 and the area of ​​the solder ribbon 1 blocking the solar cell 2, affecting the photoelectric conversion efficiency of the solar cell 2. If the number n of second bending segments 11b is too small (e.g., there are no second bending segments 11b between adjacent first bending segments 11a, i.e., the number of second bending segments 11b is 0), the ability of solder ribbon 1 to compensate for the difference in size between the solar cell 2 and solder ribbon 1 is weak, and it cannot effectively prevent the solder ribbon 1 from being subjected to excessive pulling force and falling off the pad 23. Therefore, the number n of second bending segments 11b between adjacent first bending segments 11a should be selected within a reasonable range.

[0088] Preferably, the curvature of the first bending segment 11a is less than the curvature of the second bending segment 11b, that is, the degree of bending of the first bending segment 11a is less than the degree of bending of the second bending segment 11b. This results in a smaller extension or retraction distance of the first bending segment 11a and a larger extension or retraction distance of the second bending segment 11b when the external temperature changes, thereby improving the connection reliability between the first bending segment 11a and the pad 23.

[0089] Understandably, the curvature of multiple first curved segments 11a can be the same or different, and the curvature of multiple second curved segments 11b can be the same or different.

[0090] Furthermore, such as Figure 10As shown, each curved segment has two vertices, that is, each first curved segment 11a has two vertices and each second curved segment 11b has two vertices. Along the first direction X, the distance between the two vertices of the first curved segment 11a is greater than the distance between the two vertices of the second curved segment 11b.

[0091] In the first curved segment 11a, one vertex is higher and the other is lower. The higher vertex is defined as the crest and the lower vertex is defined as the trough.

[0092] For example, along the extension direction of the solder strip 1, the projections of the crests of the plurality of first curved segments 11a coincide, and the projections of the troughs of the plurality of first curved segments 11a coincide, that is, the minimum distance between the plurality of first curved segments 11a and the outer peripheral surface of the solder strip 1 is the same; similarly, along the extension direction of the solder strip 1, the projections of the crests of the plurality of second curved segments 11b coincide, and the projections of the troughs of the plurality of second curved segments 11b coincide, that is, the minimum distance between the plurality of first curved segments 11a and the outer peripheral surface of the solder strip 1 is the same.

[0093] Optionally, along the extension direction of the welding strip 1, the projection of the crest of the first curved section 11a coincides with the projection of the crest of the second curved section 11b, and the projection of the trough of the first curved section 11a coincides with the projection of the trough of the second curved section 11b.

[0094] Optionally, along the extension direction of the welding strip 1, the projections of the crests of the first curved section 11a and the second curved section 11b do not coincide, including: the projections of the crests of the first curved section 11a and the second curved section 11b are distributed alternately in the radial direction of the welding strip 1, and the projections of the crests of the first curved section 11a and the second curved section 11b are distributed alternately in the circumferential direction of the welding strip 1.

[0095] Optionally, the projections of the troughs of the first curved segment 11a and the second curved segment 11b do not coincide, including: the projections of the troughs of the first curved segment 11a and the second curved segment 11b are distributed alternately in the radial direction of the welding strip 1, and the projections of the troughs of the first curved segment 11a and the second curved segment 11b are distributed alternately in the circumferential direction of the welding strip 1.

[0096] For example, along the extension direction of the solder strip 1, the projections of the peaks of the plurality of first curved segments 11a do not coincide, including: the projections of the peaks of the plurality of first curved segments 11a are spaced apart in the radial direction and spaced apart in the circumferential direction of the solder strip 1; along the extension direction of the solder strip 1, the projections of the troughs of the plurality of first curved segments 11a do not coincide, including: the projections of the troughs of the plurality of first curved segments 11a are spaced apart in the radial direction and spaced apart in the circumferential direction of the solder strip 1.

[0097] Along the extension direction of the welding strip 1, the projections of the peaks of the multiple second curved segments 11b do not coincide, including: the projections of the peaks of the multiple second curved segments 11b are spaced apart in the radial direction and spaced apart in the circumferential direction of the welding strip 1; along the extension direction of the welding strip 1, the projections of the troughs of the multiple second curved segments 11b do not coincide, including: the projections of the troughs of the multiple second curved segments 11b are spaced apart in the radial direction and spaced apart in the circumferential direction of the welding strip 1.

[0098] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A photovoltaic module, characterized in that, The photovoltaic module includes solar cells (2) and solder strips (1), wherein the solder strips (1) connect adjacent solar cells (2). The welding strip (1) includes an inner core (11) and an outer shell (12). The inner core (11) includes a plurality of continuously arranged curved segments. The outer shell (12) wraps around the outside of the inner core (11). The curvature of the welding strip (1) is less than the minimum curvature of the curved segments. The curved section includes a first curved section (11a) and a second curved section (11b), the first curved section (11a) being connected to the battery cell (2), and the second curved section (11b) not being connected to the battery cell (2). A second curved segment (11b) is located between adjacent first curved segments (11a).

2. The photovoltaic module according to claim 1, characterized in that, The diameter of the welding strip (1) remains unchanged along the extension direction of the welding strip (1).

3. The photovoltaic module according to claim 1, characterized in that, The welding strip (1) extends in a straight line.

4. The photovoltaic module according to claim 1, characterized in that, The cross-sectional shape of the welding strip (1) is circular, elliptical, triangular or rectangular.

5. The photovoltaic module according to claim 1, characterized in that, The diameter d1 of the inner core (11) satisfies: 100μm≤d1≤400μm; And / or, the diameter d2 of the welding strip (1) satisfies: 105μm≤d2≤500μm.

6. The photovoltaic module according to claim 1, characterized in that, The minimum distance d3 between the outer peripheral surface of the inner core (11) and the outer peripheral surface of the outer shell (12) satisfies: 5μm≤d3≤100μm.

7. The photovoltaic module according to claim 1, characterized in that, Along the extension direction of the welding strip (1), the length L of the bent section satisfies: 1mm≤L≤20mm.

8. The photovoltaic module according to any one of claims 1-7, characterized in that, The inner core (11) is made of copper wire, and the outer shell (12) is made of tin.

9. The photovoltaic module according to any one of claims 1-7, characterized in that, Between adjacent first curved segments (11a), the number n of second curved segments (11b) satisfies: 1≤n≤20.

10. The photovoltaic module according to any one of claims 1-7, characterized in that, The curvature of the first curved segment (11a) is less than the curvature of the second curved segment (11b).

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