Back-contact battery string group and photovoltaic module

Abstract

A back-contact battery string group and a photovoltaic module, which relate to the technical field of solar power generation. The back-contact battery string group comprises at least two battery strings, wherein each battery string comprises a plurality of cells that are arranged in a second direction; and solder strips, wherein two adjacent cells in each battery string are electrically connected by means of a plurality of solder strips that are arranged in a first direction, and the distance between two adjacent solder strips in the first direction in each battery string is d1. In each battery string, the solder strips adjacent to the edges of the cells in the first direction are end-portion solder strips, the distance between the end-portion solder strips of two adjacent battery strings in the first direction is d2, and 0.6≤d2 / d1<1, so as to reduce the probability of pressures borne by the cells not being uniform due to the flow of a molten adhesive and the impact of the molten adhesive on the solder strips, thereby reducing the risk of position offset of the solder strips; moreover, the two adjacent end-portion solder strips can jointly disperse stress in the vicinity of the edges of the cells, thereby reducing stress concentration and the occurrence of hidden cracks or breakage of the cells.

Description

Back contact battery string and photovoltaic module

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese application No. 2023110430414 filed on August 17, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of solar power generation technology, and in particular to a back-contact cell string and a photovoltaic module. Background Art

[0004] Photovoltaic modules are constructed from multiple cells through a series of processes, including string welding, splicing, laying, and lamination. During string welding, multiple cells are sequentially connected using welding ribbons to form a string. However, the height difference between the welding ribbons and the cells can easily cause stress concentration at the edges of the cells during the lamination process, leading to hidden cracks or breakage.

[0005] Summary of the Invention

[0006] The purpose of the present application is to provide a back-contact cell string and photovoltaic module to reduce the probability of uneven pressure on the cell caused by the flow of molten glue and the impact of the molten glue on the welding ribbon, thereby reducing the risk of position displacement of the welding ribbon. At the same time, the two adjacent end welding ribbons can jointly disperse the stress near the edge of the cell, further reducing stress concentration, thereby reducing the possibility of hidden cracks or breakage of the cell.

[0007] In order to achieve the above objectives, this application provides the following technical solutions:

[0008] A back-contact battery string assembly includes at least two battery strings arranged along a first direction, the battery strings comprising:

[0009] A plurality of battery cells arranged along a second direction;

[0010] A welding ribbon extending along the second direction, the welding ribbon being connected to the battery cell, two adjacent battery cells in the battery string being electrically connected via a plurality of welding ribbons arranged along the first direction, and a distance d1 between two adjacent welding ribbons in the battery string along the first direction;

[0011] In each battery string, the welding strip adjacent to the edge of the battery cell along the first direction is the end welding strip, and the distance between the end welding strips of two adjacent battery strings along the first direction is d2, 0.6≤d2 / d1<1.

[0012] In the present application, the ratio of the distance d2 between the end welding strips of two adjacent battery strings along the first direction to the distance d1 between two adjacent welding strips in the battery string along the first direction is set within a reasonable range, that is, 0.6≤d2 / d1<1. In this way, the distance d2 between the end welding strips of two adjacent battery strings is appropriately smaller than the distance d1 between two adjacent welding strips in the battery string, preventing the distance d2 between the end welding strips of two adjacent battery strings from being too large, thereby reducing the amount of glue flowing between the end welding strips of the two adjacent battery strings, reducing the probability of uneven pressure on the battery cells due to the flow of molten glue, and reducing the impact of molten glue on the welding strips, thereby reducing the risk of welding strip position shifting. Moreover, the two adjacent end welding strips can jointly disperse the stress near the edge of the battery cell, further reducing stress concentration, thereby reducing the risk of hidden cracks or breakage of the battery cell.

[0013] In the above embodiment, the situation where the distance d2 between the end welding strips of two adjacent battery strings is too small is also avoided, thereby preventing the end welding strips of two adjacent battery strings from being too close to each other and causing a short circuit.

[0014] In one implementation, along the first direction, the distance between the end weld ribbon and the edge of the cell is d3, where 0.2≤d3 / d2≤0.4. This arrangement ensures a reasonable distance between the end weld ribbon and the cell edge. During the lamination process, the end weld ribbon can disperse stress near the cell edge, preventing stress concentration near the cell edge that could lead to cell cracking or breakage. Furthermore, if the end weld ribbon is too close to the cell edge, the probability of cell edge cracking increases, and current collection efficiency is affected.

[0015] In one implementation, d3 is 1mm-6mm, which can prevent the end welding ribbon from being too close to the edge of the battery cell, reducing the risk of short circuit of the end welding ribbons of adjacent battery strings, while reducing stress concentration near the edge of the battery cell, thereby reducing the situation of hidden cracks or breakage of the battery cell; and / or, d1 is 8mm-11mm. In this way, the welding ribbons are set at a reasonable distance, and multiple welding ribbons can jointly disperse the pressure during the lamination process, further reducing the risk of stress concentration in the battery cell.

[0016] In one implementation, d2 is 3mm-12mm, which ensures a reasonable distance between the end welding strip and the edge of the battery cell while ensuring a reasonable string spacing, preventing the risk of overlapping of two adjacent battery strings during the lamination process, reducing stress concentration near the edge of the battery cell, and thus reducing the situation of hidden cracks or breakage of the battery cell; and / or, the string spacing between two adjacent battery strings along the first direction is d4, d4 is 0.5mm-2.5mm, which ensures a reasonable string spacing between adjacent battery strings, can prevent the risk of overlapping of two adjacent battery strings during the lamination process, and also prevents the string spacing between two adjacent battery strings along the first direction from being too large, which leads to an increase in the overall size of the photovoltaic module.

[0017] In one implementation, each cell has a chamfered edge and a non-chamfered edge on both sides along the second direction. The chamfered edge of a cell is adjacent to the chamfered edge of an adjacent cell and electrically connected via a soldering tape, while the non-chamfered edge of a cell is adjacent to the non-chamfered edge of another adjacent cell and electrically connected via a soldering tape. This facilitates alignment of the chamfered edges of adjacent cells, as well as alignment of the non-chamfered edges of adjacent cells, during the cell layout process. This avoids the difficulty of positioning the chamfered and non-chamfered edges of adjacent cells, while also optimizing the overall strength and aesthetics of the battery string.

[0018] In one implementation, in each battery string, two adjacent battery cells with non-chamfered edges are electrically connected via m welding ribbons, where m is an even number; two adjacent battery cells with chamfered edges are electrically connected via n welding ribbons, where n is an odd number, and mn = 1. In this solution, among the multiple welding ribbons connected to the same battery cell, the two end welding ribbons located on the side along the first direction can be located between two adjacent battery cells with non-chamfered edges. When designing the distance d3 between the end welding ribbons and the battery cell edge, there is no need to consider the issue of the end welding ribbons avoiding the chamfered area. As a result, the distance d3 between the end welding ribbons and the battery cell edge is not restricted by the chamfered area, which facilitates the rational design of the distance d3 between the end welding ribbons and the battery cell edge.

[0019] In one implementation, the end welding ribbon is located between two adjacent cells with non-chamfered edges, and the extension line of the end welding ribbon passes through the chamfered area of ​​the cell. This allows for the installation of more welding ribbons, reduces stress concentration near the cell edges, and thus reduces the risk of cell cracking or breakage. It also prevents the end welding ribbon from overlapping the cell chamfered area, thus avoiding the end welding ribbon hanging in the chamfered area and causing uneven stress, thus preventing cell edge cracking or fragmentation that may occur during the lamination process.

[0020] In one implementation, along the second direction, the spacing between two adjacent cells with chamfered edges is greater than the spacing between two adjacent cells with non-chamfered edges. This allows the chamfered edges of two adjacent cells to be spaced farther apart. During lamination, the chamfered edges of two adjacent cells deform and become closer, making contact or overlap less likely. This prevents cell overlap and reduces the risk of cell overlap.

[0021] In one implementation, along the second direction, the spacing between two adjacent battery cells with chamfered edges is 0.3mm-1.3mm; and / or, the spacing between two adjacent battery cells with non-chamfered edges is 0.1mm-1.1mm. While reducing the risk of battery cell paralleling, it also prevents the overall length of the battery string from being too long, thereby improving the stability of the connection between adjacent battery cells.

[0022] In one implementation, the first polarity connection portion of a battery cell is electrically connected to the second polarity connection portion of an adjacent battery cell through a welding ribbon, and the second polarity connection portion of the battery cell is electrically connected to the first polarity connection portion of another adjacent battery cell through a welding ribbon, and the welding ribbon connected to the first polarity connection portion of the battery cell and the welding ribbon connected to the second polarity connection portion of the battery cell are alternately arranged along a first direction; wherein the first polarity connection portion and the second polarity connection portion have opposite polarities, which can improve the current collection efficiency, and the current inside the battery cell is more uniform, thereby reducing the current loss inside the battery.

[0023] In one implementation, the first polarity connection portion and the second polarity connection portion are the P-type doped layer and N-type doped layer of the cell, respectively. For gridless or busbarless cells, the solder ribbon can be directly electrically connected to the P-type and N-type doped layers of the cell, achieving electrical connection between adjacent cells. This increases module power by reducing shading and resistance losses, while also reducing processing costs.

[0024] In one implementation, the first polarity connection portion and the second polarity connection portion are respectively a positive grid line and a negative grid line of the battery cell.

[0025] A photovoltaic module includes at least one back-contact cell string group, wherein the back-contact cell string group is any one of the back-contact cell strings described above.

[0026] Compared with the related art, the beneficial effects of the photovoltaic module provided by the embodiment of the present application are the same as the beneficial effects of the above-mentioned back-contact battery string group, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0028] FIG1 is a schematic diagram of a battery string and a welding ribbon provided in an embodiment of the present application;

[0029] FIG2 is a partial schematic diagram of adjacent battery strings along a first direction provided by an embodiment of the present application.

[0030] Reference numerals:

[0031] 1-cell, 1a-non-chamfered edge, 1b-chamfered edge, 2-weld strip, 2a-end weld strip. DETAILED DESCRIPTION

[0032] To make the technical problems, technical solutions, and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely intended to explain this application and are not intended to limit this application.

[0033] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0034] 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 technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0035] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships 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 direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on this application.

[0036] 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 or electrical connections; 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 the specific circumstances.

[0037] As shown in Figures 1-2, the back-contact battery string group (hereinafter referred to as the battery string group) provided in the present application includes at least two battery strings arranged along a first direction, that is, the battery string group includes two or more battery strings, and the multiple battery strings of the battery string group are arranged along the first direction, and the multiple battery strings of the battery string group are connected in series or in parallel.

[0038] Each battery string includes two or more battery cells 1 and a soldering ribbon 2. Each battery string includes two or more battery cells 1, and the battery strings are arranged along a second direction. The soldering ribbon 2 extends along the second direction, i.e., the length of the soldering ribbon 2 extends along the second direction.

[0039] The welding ribbons 2 are connected to the battery cells 1. Two adjacent battery cells 1 in the battery string are electrically connected via a plurality of welding ribbons 2 arranged along a first direction. Specifically, the plurality of welding ribbons 2 arranged along the first direction connect the two adjacent battery cells 1 in the battery string in series. The plurality of welding ribbons 2 between two adjacent battery cells 1 are arranged along the first direction. One end of the welding ribbon 2 is connected to one battery cell 1, and the other end of the welding ribbon 2 is connected to the other battery cell 1.

[0040] The distance between two adjacent solder ribbons 2 along the first direction in each battery string is d1. That is, among the multiple solder ribbons 2 connected to the same battery cell 1, the distance between two adjacent solder ribbons 2 along the first direction is d1. Specifically, the distance between the edges of two adjacent solder ribbons 2 closest to each other is d1.

[0041] In each cell string, the solder ribbon 2 adjacent to the edge of the cell 1 along the first direction is the end solder ribbon 2a. That is, among the multiple solder ribbons 2 connected to the same cell 1, the solder ribbon 2 closest to the edge of the cell 1 along the first direction is the end solder ribbon 2a. The distance between the end solder ribbons 2a of two adjacent cell strings along the first direction is d2. Specifically, the distance between the edges of the end solder ribbons 2a of two adjacent cell strings along the first direction is d2, and 0.6 ≤ d2 / d1 < 1.

[0042] During the lamination process, the adhesive film layer of the photovoltaic module is heated and melted. The molten adhesive is fluid. If the distance d2 between the end welding ribbons 2a of two adjacent cell strings along the first direction is large, the molten adhesive can easily flow between the end welding ribbons 2a of the two adjacent cell strings and into the gap between the two adjacent cell strings. The molten adhesive is unevenly distributed after flowing, resulting in uneven pressure on the cell 1, which can easily cause cracks or breakage in the cell 1. In addition, the molten adhesive can easily impact the welding ribbon 2 during its flow, causing the welding ribbon 2 to shift in position.

[0043] Furthermore, the soldering ribbon 2 itself has a certain height. Typically, the cross-section of the soldering ribbon 2 is circular, with a diameter of approximately 0.25 mm. After the soldering ribbon 2 is connected to the cell 1, a certain height difference is formed between the soldering ribbon 2 and the surface of the cell 1. During the lamination process, stress concentration is likely to occur near the location where the cell 1 connects to the soldering ribbon 2, causing the cell 1 to crack or break. The applicant, through research into the lamination process of photovoltaic modules, has found that a greater number of soldering ribbons 2 and a smaller spacing between the soldering ribbons 2 result in more uniform stress distribution across the cell 1 during lamination, facilitating stress distribution. Conversely, a smaller number of soldering ribbons 2 and a larger spacing between the soldering ribbons 2 result in a greater likelihood of stress concentration across the cell 1 during lamination, leading to cracking or breakage. As can be seen from the above, if the distance d2 between the end soldering ribbons 2a of two adjacent cell strings along the first direction is too large, not only will molten adhesive easily flow between the end soldering ribbons 2a of the two adjacent cell strings, resulting in uneven stress distribution across the cell 1, but the soldering ribbons 2 near the edges of the cell 1 will be more distant, making stress distribution less likely and more likely to cause cracking or breakage.

[0044] Based on the above, in the embodiment of the present application, the ratio of the distance d2 between the end welding ribbons 2a of two adjacent cell strings along the first direction to the distance d1 between two adjacent welding ribbons 2 in the cell string along the first direction is set within a reasonable range, namely, 0.6 ≤ d2 / d1 < 1. This setting ensures that the distance d2 between the end welding ribbons 2a of two adjacent cell strings is appropriately smaller than the distance d1 between two adjacent welding ribbons 2 in the cell string, preventing the distance d2 between the end welding ribbons 2a of two adjacent cell strings from being too large. This reduces the amount of glue flowing between the end welding ribbons 2a of the two adjacent cell strings, reduces the probability of uneven pressure on the cell 1 due to the flow of molten glue, and reduces the impact of molten glue on the welding ribbons 2, thereby reducing the risk of positional shifting of the welding ribbons 2. Furthermore, the two adjacent end welding ribbons 2a can jointly distribute stress near the edge of the cell 1, further reducing stress concentration and thus minimizing the risk of hidden cracks or breakage in the cell 1. Furthermore, if the end welding ribbons of the cell are too close to the cell edge, the probability of hidden cracks at the cell edge increases, and the current collection efficiency is affected.

[0045] In the above embodiment, the distance d2 between the end welding strips 2a of two adjacent battery strings is also avoided from being too small, thereby preventing the end welding strips 2a of two adjacent battery strings from being too close to each other and causing a short circuit.

[0046] As shown in Figure 2, along the first direction, the distance between the end welding ribbon 2a and the edge of the battery cell 1 is d3. Specifically, along the first direction, the distance between the edge of the end welding ribbon 2a on the side closest to the edge of the battery cell 1 and the edge of the battery cell 1 is d3, and 0.2≤d3 / d2≤0.4. This arrangement ensures a reasonable distance between the end welding ribbon 2a and the edge of the battery cell 1. During the lamination process, the end welding ribbon 2a can disperse the stress near the edge of the battery cell 1, preventing stress concentration near the edge of the battery cell 1 from causing hidden cracks or breakage in the battery cell 1. Of course, d3 / d2 can also be slightly greater than 0.4, or slightly less than 0.2, and this is not limited here.

[0047] In one specific embodiment, along the first direction, the distance d3 between the end welding ribbon 2a and the edge of the cell 1 is between 1 mm and 6 mm. When the distance d3 between the end welding ribbon 2a and the edge of the cell 1 is less than 1 mm, the distance between the end welding ribbons 2a of adjacent cell strings is small, which can easily cause a short circuit. When the distance d3 between the end welding ribbon 2a and the edge of the cell 1 is greater than 6 mm, it can easily lead to stress concentration near the edge of the cell 1. Therefore, keeping the distance d3 between the end welding ribbon 2a and the edge of the cell 1 within the range of 1 mm to 6 mm can prevent the distance between the end welding ribbon 2a and the edge of the cell 1 from being too close, reducing the risk of short circuits between the end welding ribbons 2a of adjacent cell strings, while also reducing stress concentration near the edge of the cell 1, thereby reducing the risk of hidden cracks or breakage in the cell 1. For example, the distance d3 between the end welding ribbon 2a and the edge of the cell 1 can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, or 6 mm.

[0048] Furthermore, along the first direction, the distance d1 between two adjacent welding ribbons 2 is 8 mm to 11 mm. That is, among multiple welding ribbons 2 connected to the same solar cell 1, the distance between two adjacent welding ribbons 2 along the first direction is 8 mm to 11 mm. This arrangement allows the welding ribbons 2 to be spaced at a reasonable distance, allowing the multiple welding ribbons 2 to distribute pressure during lamination, further reducing the risk of stress concentration in the solar cell 1. For example, along the first direction, the distance d1 between two adjacent welding ribbons 2 is 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, 10.5 mm, or 11 mm, etc.

[0049] Preferably, the distance d2 between the end welding ribbons 2a of two adjacent cell strings along the first direction is 3 mm to 12 mm. Since the distance d2 between the end welding ribbons 2a of two adjacent cell strings includes the distance d3 between the end welding ribbon 2a and the edge of the cell 1 and the string spacing d4 between two adjacent cell strings along the first direction, the distance d2 between the end welding ribbons 2a of two adjacent cell strings is within the range of 3 mm to 12 mm. This ensures a reasonable distance between the end welding ribbon 2a and the edge of the cell 1 while also ensuring a reasonable string spacing. This prevents the risk of overlapping of two adjacent cell strings during the lamination process and reduces stress concentration near the edge of the cell 1, thereby reducing the risk of hidden cracks or breakage of the cell 1. For example, the distance d2 between the end welding ribbons 2a of two adjacent cell strings along the first direction can be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, or 12 mm, and is preferably 7 mm to 10 mm.

[0050] In addition, the string spacing between two adjacent cell strings along the first direction is d4, that is, along the first direction, the distance between the edges of the cell 1 of adjacent cell strings close to each other is d4, and d4 is in the range of 0.5mm-2.5mm. When the string spacing d4 between two adjacent cell strings along the first direction is less than 0.5mm, the string spacing between adjacent cell strings is small, and the two adjacent cell strings are likely to overlap during the lamination process; when the string spacing d4 between two adjacent cell strings along the first direction is greater than 2.5mm, the string spacing between the two adjacent cell strings is too large, resulting in an increase in the overall size of the photovoltaic module. Therefore, setting the string spacing d4 between two adjacent cell strings along the first direction within the range of 0.5mm-2.5mm not only ensures a reasonable string spacing between adjacent cell strings, but also prevents the risk of overlapping between adjacent cell strings during the lamination process. It also prevents the string spacing between two adjacent cell strings along the first direction from being too large, which would increase the overall size of the photovoltaic module. For example, the string spacing d4 between two adjacent battery strings along the first direction can be 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, or 2.5 mm, etc. Of course, the string spacing d4 between two adjacent battery strings can also be slightly larger than 2.5 mm depending on actual conditions, and this is not limited here.

[0051] The cell 1 is usually formed by cutting a single crystal silicon rod into a square. Since the single crystal silicon rod is generally cylindrical, in order to maximize the illumination area and save silicon rod material, the cell 1 formed by cutting a single crystal silicon rod into a square usually has rounded corners. In order to achieve the purpose of smoother corners of the cell 1 and reduce corner stress, it is usually necessary to further process the rounded corners so that the cell 1 has four smooth chamfers. In addition, in order to make the cell 1 have different specifications and can be used in different environments, the cell 1 can be further cut into multiple small-sized cell cells 1. After cutting, one side of the cell 1 is a chamfered edge 1b with a chamfer, and the other side is a non-chamfered edge 1a without a chamfer.

[0052] In this embodiment, the two sides of any battery cell 1 along the second direction are respectively a chamfered edge 1b and a non-chamfered edge 1a, that is, the two opposite sides of the battery cell 1 along the second direction are respectively a chamfered edge 1b and a non-chamfered edge 1a, which does not mean that the edges of the battery cell 1 are parallel to the second direction. Specifically, if one side of the battery cell 1 has chamfers at both ends along the first direction, this side of the battery cell 1 is the chamfered edge 1b; the other side of the battery cell 1 is a straight edge along the first direction, and this side of the battery cell 1 is the non-chamfered edge 1a.

[0053] The chamfered edge 1b of a cell 1 is adjacent to the chamfered edge 1b of an adjacent cell 1 and electrically connected via a soldering ribbon 2. The non-chamfered edge 1a of a cell 1 is adjacent to the non-chamfered edge 1a of another adjacent cell 1 and electrically connected via a soldering ribbon 2. Specifically, in each cell string, the chamfered edges 1b of adjacent cells 1 are adjacent to the chamfered edges 1b, and the non-chamfered edges 1a of adjacent cells 1 in the cell string are adjacent to the non-chamfered edges 1a. In the cell string, if the three cells 1 arranged sequentially along the second direction are the first cell, the second cell, and the third cell, then the chamfered edge 1b of the first cell is adjacent to the chamfered edge 1b of the second cell, and the non-chamfered edge 1a of the second cell is adjacent to the non-chamfered edge 1a of the third cell. This arrangement facilitates alignment of the chamfered edges 1b of adjacent cells 1, as well as alignment of the non-chamfered edges 1a of adjacent cells 1, during the layout process of the cells 1. This avoids the difficulty of positioning the chamfered edges and non-chamfered edges 1a of adjacent cells 1, while also optimizing the overall strength and aesthetics of the battery string. Of course, within a battery string, the chamfered edge 1b of a cell 1 can also be adjacent to the non-chamfered edge 1a of an adjacent cell 1, and the non-chamfered edge 1a of a cell 1 can also be adjacent to the chamfered edge 1b of another adjacent cell 1, without limitation herein.

[0054] Furthermore, in each battery string, two adjacent battery cells 1 with non-chamfered edges 1a are electrically connected via m welding ribbons 2, where m is an even number; two adjacent battery cells 1 with chamfered edges 1b are electrically connected via n welding ribbons 2, where n is an odd number, and mn = 1. For example, m can be 10 and n can be 9, meaning that there are 19 welding ribbons 2 connected to a battery cell 1. This battery cell 1 is electrically connected to battery cells 1 adjacent to non-chamfered edges 1a via 10 welding ribbons 2 and to battery cells 1 adjacent to chamfered edges 1b via 9 welding ribbons 2. Of course, m and n can also be other values, such as m being 8 and n being 7, which can be determined by those skilled in the art based on actual circumstances. Two adjacent battery cells 1 with non-chamfered edges 1a are electrically connected via m+n welding ribbons 2, meaning that two adjacent battery cells 1 with non-chamfered edges 1a are electrically connected via an odd number of welding ribbons 2. In this embodiment, among the multiple welding strips 2 connected to the same battery cell 1, the two end welding strips 2a located on the side along the first direction can be located between two adjacent battery cells 1 with no chamfered edges 1a. When designing the distance d3 between the end welding strip 2a and the edge of the battery cell 1, there is no need to consider the problem of the end welding strip 2a avoiding the chamfered area, so that the distance d3 between the end welding strip 2a and the edge of the battery cell 1 is not restricted by the chamfered area, which is conducive to the reasonable design of the distance d3 between the end welding strip 2a and the edge of the battery cell 1.

[0055] Preferably, the end weld strip 2a is located between two adjacent battery cells 1 with non-chamfered edges 1a, that is, the end weld strip 2a is used to electrically connect two adjacent battery cells 1 with non-chamfered edges 1a. In this way, the end weld strip 2a does not need to avoid the chamfered area. Along the second direction, the end weld strip 2a can be closer to the edge of the battery cell 1, and even the extension line of the end weld strip 2a passes through the chamfered area of ​​the battery cell 1. In this way, a larger number of weld strips can be set, reducing stress concentration near the edge of the battery cell 1, thereby reducing the situation of hidden cracks or breakage of the battery cell 1, and at the same time avoiding the overlap of the end weld strip 2a and the chamfered area of ​​the battery cell 1, thereby avoiding the situation where the end weld strip 2a is suspended in the chamfered area, resulting in uneven stress, and preventing hidden cracks or fragments at the edge of the battery cell 1 that may be caused during the lamination process. It is worth noting that in this embodiment, the two battery cells 1 adjacent to the chamfered edges 1b are electrically connected only through the remaining welding strips 2 located between the two end welding strips 2a. The remaining welding strips 2 located between the two end welding strips 2a are originally far away from the edge of the battery cell 1, which makes it easier for the welding strips 2 between the two battery cells 1 adjacent to the chamfered edges 1b to avoid the chamfered area and not overlap with the chamfered area.

[0056] Of course, according to actual conditions, two adjacent battery cells 1 without chamfered edges 1a can be electrically connected through an odd number of welding strips 2, and two adjacent battery cells 1 with chamfered edges 1b can be electrically connected through an even number of welding strips 2. In this way, the end welding strip 2a is located between the two adjacent battery cells 1 without chamfered edges 1a, and the end welding strip 2a can pass through the chamfered area of ​​the battery cell 1, or a smaller number of end welding strips 2a can be set to avoid the chamfered area of ​​the battery cell 1.

[0057] From the above, it can be seen that in the battery string, when the number of welding ribbons 2 between two adjacent battery cells 1 with chamfered edges 1b is an odd number, and the number of welding ribbons 2 between two adjacent battery cells 1 without chamfered edges 1a is an even number, it is beneficial to set up more dense polarity connection parts, which is beneficial to faster electron extraction and improved power generation efficiency. At the same time, it avoids the welding ribbon 2 passing through the chamfered area to cause uneven stress, prevents the battery cell 1 from being broken or cracked, and improves the yield of the photovoltaic module.

[0058] Typically, multiple battery cells 1 in a battery string are welded in an evenly spaced arrangement. Equal spacing between adjacent battery cells 1 facilitates overall string welding. However, the edges of the battery cells 1 can warp after string welding. During lamination, the battery cells 1 are flattened by force, and the edges of two adjacent battery cells 1 are compressed and deformed, pushing them closer together. This reduces the spacing between the two adjacent battery cells 1 and makes them more prone to collapsing. This is especially serious when two battery cells 1 have adjacent chamfered edges 1b.

[0059] Based on the above situation, in this embodiment, along the second direction, the spacing between two adjacent cell cells 1 with chamfered edges 1b is greater than the spacing between two adjacent cell cells 1 with non-chamfered edges 1a. The spacing between two adjacent cell cells 1 with chamfered edges 1b is specifically the distance between the chamfered edges 1b of the two adjacent cell cells 1, and the spacing between two adjacent cell cells 1 with non-chamfered edges 1a is specifically the distance between the non-chamfered edges 1a of the two adjacent cell cells 1. Because there are fewer solder ribbons 2 provided between the chamfered edges 1b of adjacent cell cells 1, the connection stability between the two chamfered edges 1b of adjacent cell cells 1 is poor and prone to deformation and displacement. When the spacing between two adjacent cell cells 1 with chamfered edges 1b is greater than the spacing between two adjacent cell cells 1 with non-chamfered edges 1a, the distance between the chamfered edges 1b of the two adjacent cell cells 1 is greater. During lamination, the chamfered edges 1b of the two adjacent cell cells 1 deform and approach each other, making them less likely to contact or overlap, thereby avoiding the occurrence of cell overlap and reducing the risk of cell overlap.

[0060] Furthermore, along the second direction, the spacing between two adjacent battery cells 1 with chamfered edges 1b is 0.3mm-1.3mm. When the spacing between two adjacent battery cells 1 with chamfered edges 1b is less than 0.3mm, the distance between the chamfered edges 1b of the two adjacent battery cells 1 is relatively close, which easily leads to the phenomenon of battery cell paralleling. When the spacing between two adjacent battery cells 1 with chamfered edges 1b is greater than 1.3mm, the distance between the chamfered edges 1b of the two adjacent battery cells 1 is relatively far, resulting in an increase in the overall length of the battery string and a decrease in the stability of the connection between adjacent battery cells 1. Therefore, setting the spacing between two adjacent battery cells 1 with chamfered edges 1b to 0.3mm-1.3mm not only reduces the risk of battery cell 1 paralleling, but also prevents the overall length of the battery string from being too long, thereby improving the stability of the connection between adjacent battery cells 1. For example, the distance between two adjacent battery cells 1 with chamfered edges 1 b is 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm or 1.3 mm.

[0061] In addition, along the second direction, the spacing between two adjacent cells 1 with non-chamfered edges 1a is 0.1mm-1.1mm. When the spacing between two adjacent cells 1 with non-chamfered edges 1a is less than 0.1mm, the distance between the non-chamfered edges 1a of adjacent cells 1 is relatively close, which easily leads to cell paralleling. When the spacing between two adjacent cells 1 with non-chamfered edges 1a is greater than 1.1mm, the distance between the non-chamfered edges 1a of adjacent cells 1 is relatively far, resulting in an increase in the overall length of the battery string and a decrease in the stability of the connection between adjacent cells 1. Therefore, setting the spacing between two adjacent cells 1 with non-chamfered edges 1a to 0.1mm-1.1mm reduces the risk of cell paralleling while also preventing the overall length of the battery string from being too long and improving the stability of the connection between adjacent cells 1. Specifically, the distance between two adjacent battery cells 1 without chamfered edges 1a may be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm or 1.1 mm.

[0062] Preferably, along the second direction, the spacing between two adjacent battery cells 1 with chamfered edges 1b is 0.3mm-1.3mm, and the spacing between two adjacent battery cells 1 with non-chamfered edges 1a is 0.1mm-1.1mm. For example, when the spacing between two adjacent battery cells 1 with chamfered edges 1b is 0.3mm, the spacing between two adjacent battery cells 1 with non-chamfered edges 1a is 0.1mm-0.2mm; when the spacing between two adjacent battery cells 1 with non-chamfered edges 1a is 1.1mm, the spacing between two adjacent battery cells 1 with chamfered edges 1b is 1.2mm-1.3mm. When the spacing between two adjacent battery cells 1 with chamfered edges 1b is 0.6mm, the spacing between two adjacent battery cells 1 with non-chamfered edges 1a is 0.5mm; when the spacing between two adjacent battery cells 1 with chamfered edges 1b is 0.9mm, the spacing between two adjacent battery cells 1 with non-chamfered edges 1a is 0.7mm, etc. Those skilled in the art can set the spacing between two adjacent battery cells 1 with chamfered edges 1b and the spacing between two adjacent battery cells 1 with non-chamfered edges 1a according to actual conditions.

[0063] In each of the above embodiments, the first polarity connection portion of a cell 1 is electrically connected to the second polarity connection portion of an adjacent cell 1 via a soldering ribbon 2, and the second polarity connection portion of a cell 1 is electrically connected to the first polarity connection portion of another adjacent cell 1 via a soldering ribbon 2, wherein the first polarity connection portion and the second polarity connection portion are of opposite polarity. Specifically, in a cell string, if the three cell 1 arranged sequentially along the second direction are a first cell, a second cell, and a third cell, the first polarity connection portion of the second cell is electrically connected to the second polarity connection portion of the first cell via a soldering ribbon 2, and the second polarity connection portion of the second cell is electrically connected to the first polarity connection portion of the third cell via a soldering ribbon 2, thereby achieving the series connection of the first, second, and third cell.

[0064] Furthermore, the soldering ribbons 2 connected to the first polarity connection portion of the battery cell 1 and the soldering ribbons 2 connected to the second polarity connection portion of the battery cell 1 are arranged alternately and spaced apart along the first direction. The first polarity connection portion and the second polarity connection portion in the battery cell 1 can be arranged alternately and spaced apart along the first direction. In other words, in the battery cell 1, a second polarity connection portion is provided between two adjacent first polarity connection portions along the first direction, and a first polarity connection portion is provided between two adjacent second polarity connection portions along the first direction. Since the soldering ribbons 2 are connected to the first polarity connection portion or the second polarity connection portion, the soldering ribbons 2 connected to the first polarity connection portion of the same battery cell 1 and the soldering ribbons 2 connected to the second polarity connection portion of the same battery cell 1 are also adaptively arranged alternately and spaced apart along the first direction. This improves the current collection efficiency, makes the current inside the battery cell 1 more uniform, and reduces the current loss inside the battery.

[0065] In one specific embodiment, the first polarity connection portion and the second polarity connection portion are respectively the P-type doped layer and the N-type doped layer of the cell 1. Specifically, the first polarity connection portion is the P-type doped layer and the second polarity connection portion is the N-type doped layer; alternatively, the first polarity connection portion is the N-type doped layer and the second polarity connection portion is the P-type doped layer. For gridless or busbarless cell 1, the soldering ribbon can be directly electrically connected to the P-type doped layer and the N-type doped layer of the cell 1 to achieve electrical connection between adjacent cells 1, thereby increasing module power by reducing shading and resistance loss, while also reducing processing costs.

[0066] In another specific embodiment, the first polarity connection portion and the second polarity connection portion are respectively the positive and negative grid lines of the battery cell 1. Specifically, the first polarity connection portion is the positive grid line and the second polarity connection portion is the negative grid line; alternatively, the first polarity connection portion is the negative grid line and the second polarity connection portion is the positive grid line. A plurality of positive and negative grid lines are arranged alternately and spaced along a first direction on the battery cell 1. The positive and negative grid lines extend along a second direction. The welding ribbon 2 is connected to the positive or negative grid lines to achieve electrical connection between adjacent battery cells 1.

[0067] Embodiments of the present application further provide a photovoltaic module, comprising at least one back-contact cell string, wherein the back-contact cell string is a back-contact cell string as provided in any of the above embodiments. When the photovoltaic module comprises multiple back-contact cell strings, the multiple back-contact cell strings can be arranged along the second direction, and the multiple back-contact cell strings can be connected in parallel.

[0068] Compared with the related art, the beneficial effects of the photovoltaic module provided by the embodiment of the present application are the same as the beneficial effects of the above-mentioned back-contact battery string group, which will not be described in detail here.

[0069] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0070] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A back contact battery string, wherein: The invention comprises at least two battery strings arranged along a first direction, wherein the battery string comprises: A plurality of battery cells arranged along a second direction; A welding strip extending along the second direction, the welding strip being connected to the battery cell, two adjacent battery cells in the battery string being electrically connected via a plurality of welding strips arranged along the first direction, and a distance between two adjacent welding strips in the battery string along the first direction being d1; In each battery string, the welding strip adjacent to the edge of the battery cell along the first direction is the end welding strip, and the distance between the end welding strips of two adjacent battery strings along the first direction is d2, 0.6≤d2 / d1<1.

2. The back contact battery string according to claim 1, wherein: Along the first direction, the distance between the end welding strip and the edge of the battery cell is d3, and 0.2≤d3 / d2≤0.

4.

3. The back contact battery string according to claim 2, wherein: The d3 is 1mm-6mm; and / or the d1 is 8mm-11mm.

4. The back contact battery string according to claim 1, wherein: The d2 is 3 mm-12 mm; and / or, the string spacing between two adjacent battery strings along the first direction is d4, and d4 is 0.5 mm-2.5 mm.

5. The back contact battery string according to claim 1, wherein: The two sides of any battery cell along the second direction are respectively a chamfered edge and a non-chamfered edge, the chamfered edge of the battery cell is adjacent to the chamfered edge of an adjacent battery cell and is electrically connected through a welding strip, and the non-chamfered edge of the battery cell is adjacent to the non-chamfered edge of another adjacent battery cell and is electrically connected through a welding strip.

6. The back contact battery string according to claim 5, wherein: In each battery string, two adjacent battery cells with non-chamfered edges are electrically connected via m welding strips, where m is an even number; two adjacent battery cells with chamfered edges are electrically connected via n welding strips, where n is an odd number, and mn=1.

7. The back contact battery string according to claim 6, wherein: The end welding strip is located between two adjacent battery cells with non-chamfered edges, and an extension line of the end welding strip passes through the chamfered area of ​​the battery cell.

8. The back contact battery string according to claim 5, wherein: Along the second direction, the distance between two adjacent battery cells with chamfered edges is greater than the distance between two adjacent battery cells with non-chamfered edges.

9. The back contact battery string according to claim 8, wherein: Along the second direction, the distance between two adjacent battery cells with chamfered edges is 0.3 mm-1.3 mm; and / or the distance between two adjacent battery cells with non-chamfered edges is 0.1 mm-1.1 mm.

10. The back contact battery string according to any one of claims 1 to 9, wherein: The first polarity connection part of the battery cell is electrically connected to the second polarity connection part of an adjacent battery cell through a welding strip, and the second polarity connection part of the battery cell is electrically connected to the first polarity connection part of another adjacent battery cell through a welding strip, and the welding strip connected to the first polarity connection part of the battery cell and the welding strip connected to the second polarity connection part of the battery cell are alternately arranged along a first direction; wherein the first polarity connection part and the second polarity connection part are of opposite polarity.

11. The back contact battery string according to claim 10, wherein: The first polarity connection portion and the second polarity connection portion are respectively a P-type doping layer and an N-type doping layer of the battery cell.

12. The back contact battery string according to claim 10, wherein: The first polarity connection portion and the second polarity connection portion are respectively the positive pole grid line and the negative pole grid line of the battery cell.

13. A photovoltaic module, wherein: The method comprises at least one back-contact battery string group, wherein the back-contact battery string group is the back-contact battery string group according to any one of claims 1 to 12.

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