Solar cell module and photovoltaic system

Abstract

The invention is applicable to the field of photovoltaic technology, and provides a solar cell module and a photovoltaic system, the solar cell module comprises a plurality of cells which are sequentially arranged in an overlapping manner along a first direction, and two adjacent cells have an overlapping area; the first welding strips and the second welding strips are alternately arranged on the back faces of the battery pieces in the second direction at intervals, and the first welding strips and the second welding strips are alternately arranged on the back faces of the battery pieces in the second direction at intervals. The second welding strip comprises a first connecting section, a third connecting section and a second connecting section arranged between the first connecting section and the third connecting section, the first connecting section is arranged in one of the two adjacent battery pieces, the second connecting section is arranged in the other of the two adjacent battery pieces, and the second connecting section is arranged in the overlapping area; and the thickness of the second connecting section is thinned relative to the first connecting section and / or the third connecting section, so that the local thickness of the laminated solar cell module is reduced, and the risk of subfissure of the cells in the lamination process of the solar cell module is reduced.

Description

Technical Field

[0001] The invention belongs to the field of photovoltaic technology, and in particular relates to a solar cell assembly and a photovoltaic system. Background Art

[0002] Photovoltaic modules are used to convert solar energy into electrical energy. Photovoltaic modules include multiple photovoltaic cells, and two adjacent photovoltaic cells are connected in series through welding strips. In order to reduce the shading area, current multi-main-grid cells often use a thinner circular conductive substrate (such as a copper substrate) as the welding strip substrate. In a stacked solar cell module, adjacent cells are partially overlapped and partially too thick. Conventional circular welding strips generate stress concentration when laminated and welded with the cells, resulting in cell fragments and hidden cracks in the module, and are prone to poor welding, low welding tension and other undesirable phenomena. Summary of the invention

[0003] The present invention provides a solar cell assembly, aiming to solve the problem that in a stacked solar cell assembly, adjacent cells are partially overlapped and too thick locally, and conventional circular welding strips generate stress concentration when laminated and welded with the cells, resulting in cell fragments and hidden cracks in the assembly, and are prone to poor welding, low welding tension and other undesirable phenomena.

[0004] The present invention is implemented as follows: a solar cell assembly comprises a plurality of cells arranged in an overlapping manner in sequence along a first direction, wherein two adjacent cells have an overlapping area; a first welding strip and a second welding strip, wherein the first welding strip and the second welding strip are alternately arranged on the back side of the cell along a second direction; wherein along the first direction, the second welding strip extends from one of the two adjacent cells to the other of the two adjacent cells, and the second welding strip connects the two adjacent cells; the second welding strip comprises a first connecting section, a third connecting section and a second connecting section arranged between the first connecting section and the third connecting section, wherein the first connecting section is arranged at one of the two adjacent cells, the third connecting section is arranged at the other of the two adjacent cells, and the second connecting section is arranged at the overlapping area; the thickness of the second connecting section is less than the thickness of the first connecting section, and / or the thickness of the second connecting section is less than the thickness of the third connecting section.

[0005] Optionally, along the first direction, the length of the second connecting segment is greater than the width of the overlapping area.

[0006] Optionally, along the second direction, the width of the second connecting segment is greater than the width of the first connecting segment, and / or the width of the second connecting segment is greater than the width of the third connecting segment.

[0007] Optionally, the first connecting segment, the second connecting segment and the third connecting segment are integrally formed.

[0008] Optionally, the first connecting segment and the second connecting segment are overlapped and connected to each other, and / or the second connecting segment and the third connecting segment are overlapped and connected to each other.

[0009] Optionally, a cross-sectional area of ​​at least one of the first connecting segment and the third connecting segment is equal to a cross-sectional area of ​​the second connecting segment.

[0010] Optionally, the cross-sectional area of ​​the first connecting segment, the cross-sectional area of ​​the second connecting segment and the cross-sectional area of ​​the third connecting segment are all equal.

[0011] Optionally, the cross-sectional area of ​​the second connecting segment is larger than the cross-sectional area of ​​the first connecting segment, and / or the cross-sectional area of ​​the second connecting segment is larger than the cross-sectional area of ​​the third connecting segment.

[0012] Optionally, the first connecting segment and the third connecting segment are round wire welding strip segments, and the second connecting segment is a flat welding strip segment.

[0013] Optionally, in the first direction, the width of the overlapping area is greater than or equal to 0.1 mm and less than or equal to 0.6 mm.

[0014] Optionally, in the first direction, the length of the second connecting segment is greater than or equal to 0.5 mm and less than or equal to 2 mm.

[0015] Optionally, the thickness of the second connecting section is greater than 0.08 mm.

[0016] The present invention arranges the second welding strip connecting two adjacent battery cells in sections, the second welding strip includes a first connecting section, a third connecting section and a second connecting section arranged between the first connecting section and the third connecting section, the first connecting section is arranged at one of the two adjacent battery cells, the second connecting section is arranged at the other of the two adjacent battery cells, the second connecting section is arranged at the overlapping area, and the thickness of the second connecting section is designed to be thinner relative to the first connecting section and / or the third connecting section, thereby reducing the local thickness of the stacked solar cell module and the risk of hidden cracks in the battery cells during the lamination process of the solar cell module. The thinned second connecting section is easier to bend and easier to fit the surface of the battery cell, thereby reducing the risk of cold welding, increasing the welding tension, and improving the reliability of the module.

[0017] A photovoltaic system comprises the above-mentioned solar cell assembly. The technical effect of the present invention is the same as that of the above-mentioned solar cell assembly, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the first solar cell assembly provided by the present invention;

[0019] Figure 2 yes Figure 1 A schematic diagram of the structure at A;

[0020] Figure 3 It is a structural schematic diagram of the second solar cell assembly provided by the present invention.

[0021] Description of reference numerals:

[0022] 100, battery cell; 200, overlapping area; 300, first welding strip; 400, second welding strip; 401, first connecting section; 402, second connecting section; 403, third connecting section. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with 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 invention, and should not be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0028] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the examples of various specific processes and materials provided by the present invention, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0029] like Figure 1 As shown, in an embodiment of the present invention, a solar cell assembly includes a plurality of cells 100 arranged in sequence and overlapped along a first direction, and a first welding strip 300 and a second welding strip 400 are alternately arranged on the back of the cell 100 along a second direction. It can be understood that the cell 100 can be made of semiconductor materials, such as a P-type silicon wafer, which forms a PN junction after phosphorus diffusion. Among them, after the semiconductor structure absorbs solar energy, it excites and generates electron-hole pairs, and the electron-hole pairs are separated by the self-built electric field of the PN junction inside the semiconductor. The electrons flow into the N region and the holes flow into the P region, thereby forming a photogenerated electric field. Generally speaking, the cell 100 is a sheet structure, and the side that can absorb light energy and convert it into electrical energy is called the light-absorbing side or the front side, and the other side is called the back side. The solar cell with grid lines of both polarities formed on the back of the cell is a back contact cell.

[0030] In the embodiment of the present invention, each battery cell 100 includes a first welding strip 300 and a second welding strip 400 located on the back of the battery cell 100. Along the first direction, the second welding strip 400 extends from one of two adjacent battery cells 100 to the other of two adjacent battery cells 100, and the second welding strip 400 connects the two adjacent battery cells 100. In this way, the current of the battery cell 100 can be conducted by the welding strip. It should be noted that, among them, the two overlapping battery cells 100 are connected in parallel or in series through the same second welding strip 400, and the polarity of the first welding strip 300 connected to the grid line on each battery cell 100 can be the same or different. Similarly, the polarity of the second welding strip 400 connected to the grid line on each battery cell 100 can be the same or different. For example, if two adjacent battery cells 100 are connected in series, the first welding strip 300 on the first battery cell 100 is a welding strip connected to the positive grid line, the second welding strip 400 on the first battery cell 100 is a welding strip connected to the negative grid line, the first welding strip 300 on the second battery cell 100 is a welding strip connected to the negative grid line, and the second welding strip 400 on the second battery cell 100 is a welding strip connected to the positive grid line. In this way, the second welding strip 400 connects the first battery cell 100 and the second battery cell 100 to form a series connection. If two adjacent battery cells 100 are connected in parallel, the first welding strip 300 on the first battery cell 100 is a welding strip connected to the positive grid line, the second welding strip 400 on the first battery cell 100 is a welding strip connected to the negative grid line, the first welding strip 300 on the second battery cell 100 is a welding strip connected to the positive grid line, and the second welding strip 400 on the second battery cell 100 is a welding strip connected to the negative grid line. In this way, the second welding strip 400 connects the first battery cell 100 and the second battery cell 100 to form a parallel connection. Each battery cell 100 is substantially rectangular, wherein the substantially rectangular battery cell 100 can be, for example, a square, or another rectangle, and can have standard corners, cut corners or rounded corners, which are specifically set according to actual production needs and are not specifically limited here. Among them, the welding strip can be set on the battery cell 100 by lamination welding to play a role in guiding current. It can also be understood that the plurality of battery cells 100 may include two battery cells 100 , three battery cells 100 or any other greater number of battery cells 100 , and the specific number of battery cells 100 required may be determined based on actual usage.

[0031] In some embodiments, there is an overlapping area 200 between two adjacent battery cells 100. It is understandable that the overlapping area 200 of the battery cells 100 is not conductively connected, or in other words, the overlapping area 200 does not need to be provided with a connecting layer such as a conductive adhesive or other adhesive, and the battery cells 100 are simply overlapped, or in other words, they only need to be in contact with each other, and the two overlapping battery cells 100 are fixed and connected by the same second welding strip 400. Furthermore, there is no gap between the overlapping battery cells 100, which can well hide the second welding strip 400, and is suitable for making full-screen components.

[0032] It is understandable that the overlapping of the battery cells 100 means that two adjacent battery cells 100 overlap a portion of the area. Exemplarily, the overlapping width ranges from 0.1 mm to 0.6 mm, such as 0.1 mm, 0.2 mm, 0.4 mm or 0.6 mm, and the present invention is not limited thereto.

[0033] like Figure 2 and Figure 3 As shown, in the embodiment of the present invention, the second welding strip 400 includes a first connecting section 401, a third connecting section 403, and a second connecting section 402 disposed between the first connecting section 401 and the third connecting section 403, the first connecting section 401 is disposed at one of the two adjacent battery cells 100, the third connecting section 403 is disposed at the other of the two adjacent battery cells 100, and the second connecting section 402 is disposed at the overlapping area 200; the thickness of the second connecting section 402 is less than the thickness of the first connecting section 401, and / or, the thickness of the second connecting section 402 is less than the thickness of the third connecting section 403. It can be understood that the second welding strip 400 adopts a three-section differentiated thickness design, consisting of the first connecting section 401, the second connecting section 402 and the third connecting section 403. The first connecting section 401 is fixed to the front surface of two adjacent battery cells 100, the third connecting section 403 is fixed to the rear surface, and the middle second connecting section 402 spans the overlapping area 200 of the two battery cells 100, and its thickness is thinner than the connecting sections at both ends. By setting the thin second connecting section 402 in the overlapping area 200 of the battery cells 100, the rigidity of the welding strip is effectively reduced. When the component is thermally expanded or mechanically loaded, the thin section can produce elastic deformation, absorb strain energy, and significantly reduce the stress concentration phenomenon at the edge of the battery cell 100, which is particularly suitable for flexible components or high vibration environment applications.

[0034] In some embodiments, the first connection section 401, the second connection section 402 and the third connection section 403 are integrally formed. That is to say, the three-segment differentiated structure of the second welding strip 400 is formed by continuous processing of a single material, which can eliminate the interface defects (such as cold welding and pores) of traditional segmented welding, and improve the overall tensile strength of the welding strip. And in the component lamination process, the continuous structure can evenly disperse the shear stress and avoid hidden cracks caused by local stress concentration. Exemplarily, the second welding strip can be partially flattened by flattening to form the second connection section 402, or the second welding strip 400 can be locally rolled to form the second connection section 402, or the second welding strip 400 can be locally processed by stamping to form the second connection section 402, and the present invention is not limited to this.

[0035] In other embodiments, the first connection segment 401 and the second connection segment 402 are overlapped and connected to each other, and / or, the second connection segment 402 and the third connection segment 403 are overlapped and connected to each other. In other words, the first connection segment 401 and the second connection segment 402 may be overlapped and connected to each other, and the second connection segment 402 and the third connection segment 403 may be integrally formed; or, the first connection segment 401 and the second connection segment 402 may be integrally formed, and the second connection segment 402 and the third connection segment 403 may overlap each other; or, the first connection segment 401 and the second connection segment 402 may be overlapped and connected to each other, and the second connection segment 402 and the third connection segment 403 may be overlapped and connected to each other. The second welding strip 400 may be overlapped and connected in the above-mentioned manners, so as to improve the flexibility of the arrangement of the second welding strip 400. In addition, the overlap area (such as the 0.5-1.2 mm overlap segment) forms a controllable deformation hinge. When the solar cell module is subjected to uneven load, the overlap interface allows a micro displacement of 0.2-0.5 mm, converting the transverse shear stress into the longitudinal tensile stress, so as to reduce the peak stress of the edge of the cell 100. In addition, each segment can independently adopt a differentiated process (such as electroplating tin for the first connecting segment 401 and silver plating for the second connecting segment 402) to reduce the contact resistance of the overlap surface. When defects are found in EL detection, the overlap segment can be partially replaced (rather than the entire solder strip), so that the component rework time is shortened and the maintenance cost is reduced.

[0036] In some embodiments, along the first direction, the length of the second connecting section 402 is greater than the width of the overlapping region 200. This can effectively reduce the local height of the overlapping region 200, ensure that the second welding strip 400 portion stacked on the overlapping region 200 always has a lower thickness, and reduce the risk of hidden cracks during the lamination process of the solar cell module. In addition, the longer second connecting section 402 provides a larger deformation space when the cell 100 is heated or subjected to external force, reducing stress concentration. For example, when the temperature changes cause the cell 100 to expand or contract, the longer flexible portion can absorb more strain to prevent the welding strip or the cell 100 from cracking.

[0037] In some embodiments, along the second direction, the width of the second connecting segment 402 is greater than the width of the first connecting segment 401, and / or the width of the second connecting segment 402 is greater than the width of the third connecting segment 403. By widening the width of the second connecting segment 402 relative to the first connecting segment 401 and / or the third connecting segment 403, the contact area between the second connecting segment 402 and the cell 100 can be increased, the lamination pressure can be dispersed, the risk of hidden cracks in the cell can be reduced, and the reliability of the solar cell module can be improved.

[0038] In some embodiments, the first connection segment 401 and the third connection segment 403 are round wire welding strip segments, and the second connection segment 402 is a flat welding strip segment.

[0039] In the embodiment of the present invention, the second direction intersects with the first direction. Specifically, the second direction may be perpendicular to the first direction. Exemplarily, the first direction may be the width direction of the battery cell 100 , and the second direction may be the length direction of the battery cell 100 .

[0040] In some embodiments, the cross-sectional area of ​​at least one of the first connection segment 401 and the third connection segment 403 is equal to the cross-sectional area of ​​the second connection segment 402. Further, the cross-sectional areas of the first connection segment 401 and the second connection segment 402 may be equal, and the cross-sectional areas of the third connection segment 403 and the second connection segment 402 may be different. In this case, the second connection segment 402 may be formed by flattening the end of the first connection segment 401, or the cross-sectional areas of the first connection segment 401 and the second connection segment 402 are different, and the cross-sectional areas of the third connection segment 403 and the second connection segment 402 are equal. In this case, the second connection segment 402 may be formed by flattening the end of the third connection segment 403, or the cross-sectional areas of the first connection segment 401 and the second connection segment 402 are equal, and the cross-sectional areas of the second connection segment 402 and the third connection segment 403 are equal. In this case, the second connection segment 402 may be formed by flattening a portion (e.g., the middle portion) of a whole round wire welding strip. By controlling the cross-sectional dimensions of the second connecting section 402 to achieve resistance matching, while keeping the conductive cross-sectional area unchanged (by increasing the width to compensate for the thickness reduction), the current transmission efficiency is maintained, and the resistance distribution of the welding strip is more in line with the current density requirements, reducing the risk of local hot spots. Preferably, the cross-sectional area of ​​the first connecting section 401, the cross-sectional area of ​​the second connecting section 402, and the cross-sectional area of ​​the third connecting section 403 are all equal. When the cross-sectional area of ​​the second connecting section 402 is equal to that of the first connecting section 401 and the third connecting section 403, illustratively, the thickness of the second connecting section 402 is 0.12 mm and the width is 1.5 mm, the thickness of the first connecting section 401 and the third connecting section 403 is 0.18 mm and the width is 1.0 mm. The cross-sectional areas of the first connecting section 401, the second connecting section 402, and the third connecting section 403 are all 0.18 mm2, and the overall resistivity distribution of the welding strip tends to be consistent. At the rated operating current, the current density fluctuates less, the uniformity of the Joule heat distribution is improved, and the power loss of the solar cell module is reduced.

[0041] In other embodiments, the cross-sectional area of ​​the second connecting segment 402 is greater than the cross-sectional area of ​​the first connecting segment 401, and / or the cross-sectional area of ​​the second connecting segment 402 is greater than the cross-sectional area of ​​the third connecting segment 403. By designing the second connecting segment 402 separately, its cross-sectional area can be increased while reducing the thickness of the second connecting segment, thereby further effectively reducing the resistance of the second connecting segment and improving the current transmission efficiency.

[0042] In some embodiments, in the first direction, the width of the overlap region 200 ranges from greater than or equal to 0.1 mm to less than or equal to 0.6 mm. In this way, there is no gap between the battery cells 100, so that the solder strips can be better hidden, and there is no need to set a shielding insulating layer in the gap between the battery cells 100 to hide the solder strips. Exemplarily, the overlap width range can be 0.1 mm, 0.2 mm, 0.4 mm, 0.5 mm or 0.6 mm, and the present invention is not limited here.

[0043] In some embodiments, in the first direction, the length of the second connecting segment 402 is greater than or equal to 0.5 mm and less than or equal to 2 mm. For example, the length of the second connecting segment 402 can be 0.5 mm, 0.8 mm, 1 mm, 1.5 mm or 2 mm, which is not limited in the present invention.

[0044] In some embodiments, the thickness of the second connecting segment 402 is at least greater than 0.08 mm. By setting the thickness of the second connecting segment 402 within this range, it is possible to prevent the second connecting segment 402 from being too thin, thereby reducing the risk of the second connecting segment 402 breaking during the bending process.

[0045] In some embodiments, a photovoltaic system includes a solar cell assembly as described above. 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 can be understood that the application scenarios of the photovoltaic system are not limited to this, that is, the photovoltaic system can be applied in all fields where solar energy is required 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 solar cell assemblies. For example, multiple solar cell assemblies can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid, and then connected to the mains network to realize solar power supply.

[0046] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A solar cell module, characterized in that: It includes a plurality of battery cells arranged in an overlapping manner in sequence along a first direction, and there is an overlapping area between two adjacent battery cells; a first welding strip and a second welding strip, and the first welding strip and the second welding strip are alternately arranged on the back side of the battery cell along the second direction; wherein, along the first direction, the second welding strip extends from one of the two adjacent battery cells to the other of the two adjacent battery cells, and the second welding strip connects the two adjacent battery cells; the second welding strip includes a first connecting section, a third connecting section and a second connecting section arranged between the first connecting section and the third connecting section, the first connecting section is arranged at one of the two adjacent battery cells, the third connecting section is arranged at the other of the two adjacent battery cells, and the second connecting section is arranged at the overlapping area; the thickness of the second connecting section is less than the thickness of the first connecting section, and / or the thickness of the second connecting section is less than the thickness of the third connecting section.

2. The solar cell assembly according to claim 1, wherein: Along the first direction, the length of the second connecting segment is greater than the width of the overlapping area.

3. The solar cell assembly according to claim 1, wherein: Along the second direction, the width of the second connecting segment is greater than the width of the first connecting segment, and / or the width of the second connecting segment is greater than the width of the third connecting segment.

4. The solar cell assembly according to claim 1, wherein: The first connecting section, the second connecting section and the third connecting section are integrally formed.

5. The solar cell assembly according to claim 1, wherein: The first connecting section and the second connecting section are overlapped and connected to each other, and / or the second connecting section and the third connecting section are overlapped and connected to each other.

6. The solar cell assembly according to claim 1, wherein: The cross-sectional area of ​​at least one of the first connecting segment and the third connecting segment is equal to the cross-sectional area of ​​the second connecting segment.

7. The solar cell assembly according to claim 1, wherein: The cross-sectional area of ​​the first connecting section, the cross-sectional area of ​​the second connecting section and the cross-sectional area of ​​the third connecting section are all equal.

8. The solar cell assembly according to claim 1, wherein: The cross-sectional area of ​​the second connecting segment is larger than the cross-sectional area of ​​the first connecting segment, and / or the cross-sectional area of ​​the second connecting segment is larger than the cross-sectional area of ​​the third connecting segment.

9. The solar cell assembly according to claim 1, wherein: The first connecting section and the third connecting section are round wire welding strip sections, and the second connecting section is a flat welding strip section.

10. The solar cell assembly according to claim 1, wherein: In the first direction, the width of the overlapping area is in the range of greater than or equal to 0.1 mm and less than or equal to 0.6 mm.

11. The solar cell assembly according to claim 1, wherein: In the first direction, the length of the second connecting segment is greater than or equal to 0.5 mm and less than or equal to 2 mm.

12. The solar cell assembly according to claim 1, wherein: The thickness of the second connecting section is greater than 0.08 mm.

13. A photovoltaic system, characterized in that: The invention comprises a solar cell module as claimed in any one of claims 1 to 12.

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