Back contact cell string and photovoltaic module

Abstract

The present application provides a cell string and a photovoltaic module. The cell string comprises a plurality of cells, each cell having, orthogonal to each other, first edges and second edges; and a plurality of first electrodes which extend in a direction parallel to the first edges and are arranged on back surfaces of the cells at equal intervals in the extending direction of the second edges, each first electrode comprising a plurality of first electrode segments arranged at intervals, wherein the ratio of the length of each first electrode to the length of a first edge is greater than 98%, and the ratio of the sum of first gaps between the plurality of first electrode segments of each first electrode to the length of the first electrode is less than or equal to 6%. The photovoltaic module comprises a plurality of cell strings arranged at intervals.

Description

Back contact cell strings and photovoltaic modules

[0001] This application claims priority to Chinese patent application No. 202420476800X, filed on March 12, 2024, with the invention name “Back-contact battery string and photovoltaic module”, and the entire contents of the Chinese patent application are incorporated herein by reference. Technical Field

[0002] At least one embodiment of the present application relates to the field of photovoltaic technology, and in particular to a back-contact cell string and a photovoltaic module. Background Art

[0003] Conventional solar cells often have electrodes placed on both the front and back of the cell. The front of the cell is the light-receiving surface, so electrodes placed on the front of the cell will inevitably block a portion of the light-receiving area, reducing the cell's energy conversion efficiency.

[0004] Back-contact cells have the characteristic of arranging both the positive electrode and the negative electrode on the back of the cell, so that the light-receiving surface of the cell is not shielded by the metal electrode, thereby effectively improving the energy conversion efficiency of the cell.

[0005] Because the positive and negative electrodes of back-contact batteries are both located on the back of the cell, the first electrodes must be intermittently arranged on different doping regions of the cell, so that adjacent first electrodes have different polarities. Excessive gaps between adjacent first electrode segments within the same first electrode shorten the effective collection length of the first electrode. However, too little gap can easily lead to a short circuit when welding the pad to the first electrode, hindering current collection. Therefore, designing the first electrode to ensure a long effective collection length and a low risk of short circuiting with the pad has become a pressing technical challenge. Summary of the Invention

[0006] To solve at least one of the above and other technical problems in the prior art, the present application provides a back-contact cell string and photovoltaic module, which can enable the first electrode to have a longer effective collection length and each first electrode segment to have a shorter collection path.

[0007] An embodiment of the present application provides a back-contact battery, comprising: a plurality of battery cells, each of the battery cells having a first side and a second side that are orthogonal to each other; a plurality of first electrodes, each of the first electrodes extending in a direction parallel to the first side, and the plurality of first electrodes being equidistantly arranged on the back side of the battery cell in a direction parallel to the second side, each first electrode comprising a plurality of first electrode segments spaced apart in a direction parallel to the first side; wherein the ratio of the length of each first electrode to the length of the first side is greater than 98%, and the ratio of the sum of the first gaps between the plurality of first electrode segments of each first electrode to the length of the first electrode is less than or equal to 6%, and the length of each first electrode comprises the lengths of the plurality of first electrode segments it comprises and the sum of the first gaps between the plurality of first electrode segments it comprises.

[0008] According to an embodiment of the present application, the battery string further includes a welding strip, each of the welding strips extending in a direction parallel to the second side, passing through a first gap formed by two adjacent first electrode segments of the first electrode of one polarity, and connected to a first electrode segment of the first electrode of the other polarity; wherein, along a direction parallel to the first side, a ratio of a width of the first gap through which the welding strip passes to a width of the welding strip is configured to be 1.2 to 2.

[0009] According to an embodiment of the present application, the welding strips are configured in an even number, and the number of the first gaps provided between two adjacent first electrodes with different polarities on the same battery cell is the same.

[0010] According to an embodiment of the present application, the solder strips are configured in an odd number, and the numbers of the first gaps provided between two adjacent first electrodes with different polarities on the same battery cell are different.

[0011] According to an embodiment of the present application, on the same cell, the number of the first gaps provided between the two first electrodes with different polarities differs by 1.

[0012] According to an embodiment of the present application, on a same battery cell, the number of the first gaps provided in the first electrodes of the same polarity is configured to be 6 to 11.

[0013] According to an embodiment of the present application, on the same battery cell, the number of the above-mentioned first gaps set in the above-mentioned first electrodes of the same polarity and the above-mentioned welding strips passing through the first gaps set in the above-mentioned first electrodes are configured to be 11 to 23.

[0014] According to an embodiment of the present application, the battery string further includes an insulating layer made of an insulating material, and the insulating layer covers both ends of the first electrode segment.

[0015] According to an embodiment of the present application, at a position of one end of each first electrode segment close to the welding strip, the thickness of the insulating layer covering the end of the first electrode segment decreases in a direction toward the welding strip.

[0016] According to an embodiment of the present application, the ratio of the width of the above-mentioned welding strip to the width of the first gap between the two adjacent first electrode segments through which the welding strip passes is configured to be greater than or equal to 0.5, and a second gap is provided between the two insulating layers at the two adjacent ends of the two adjacent first electrode segments forming the first gap through which the welding strip passes, and the ratio of the width of the above-mentioned welding strip to the width of the second gap is configured to be less than or equal to 0.75.

[0017] According to an embodiment of the present application, the battery string further includes a plurality of second electrodes, each of the second electrodes extending in a direction parallel to the second side; wherein the second electrode passes through a first gap formed by two adjacent first electrode segments of the first electrode having a different polarity, and is connected to the first electrode segment of the first electrode having the same polarity.

[0018] According to an embodiment of the present application, the above-mentioned welding strip is welded to the welding pad provided on the above-mentioned second electrode, and a second gap is provided between the two insulating layers at the two adjacent ends of the two adjacent first electrode segments forming a first gap through which the welding strip passes, and the ratio of the width of the above-mentioned welding strip to the width of the above-mentioned second gap is configured to be 0.6 to 1.2.

[0019] According to an embodiment of the present application, on the same battery cell, the ratio of the sum of the first gaps between the plurality of first electrode segments of the first electrodes of different polarities to the length of the first electrodes of corresponding polarities is configured to be different.

[0020] According to an embodiment of the present application, the ratio of the sum of the first gaps between the multiple first electrode segments of the above-mentioned first electrode configured as the positive electrode to the length of the above-mentioned first electrode configured as the positive electrode is greater than the ratio of the sum of the first gaps between the multiple first electrode segments of the above-mentioned first electrode configured as the negative electrode to the length of the above-mentioned first electrode configured as the negative electrode.

[0021] An embodiment of the present application further provides a photovoltaic assembly, comprising: a plurality of battery strings, wherein the plurality of battery strings are arranged at intervals.

[0022] According to the back-contact cell string and photovoltaic module provided by this application, the length of the first electrode is configured to be greater than 98% of the length of the first side, thereby providing the first electrode with a longer effective collection length. The ratio of the sum of the first gaps between the multiple first electrode segments of each first electrode to the length of the first electrode is set to be less than or equal to 6%, further extending the effective collection length of the first electrode and making the welding between the first electrode and the welding ribbon less likely to cause a short circuit, thereby more effectively preventing leakage. In this way, the overall setting of the length of the first electrode segments and the width of the first gaps facilitates the collection of current generated by the cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a schematic structural diagram of a back-contact battery string according to an exemplary embodiment of the present application; and

[0024] FIG. 2 is a partial cross-sectional view of a portion A of the back-contact cell string of the exemplary embodiment shown in FIG. 1 .

[0025] In the drawings, the meanings of the reference numerals are as follows: 1. battery cell; 2. soldering ribbon; 21. first soldering ribbon; 22. second soldering ribbon; 3. first electrode; 31. first electrode A; 32. first electrode B; 4. insulating layer; and 5. solder. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of this application more clear, this application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0027] The terms used herein are only for describing specific embodiments and are not intended to limit this application. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0028] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0029] When expressions such as “at least one of A, B, and C, etc.” are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art. For example, “a system having at least one of A, B, and C” should include but is not limited to systems having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc. When expressions such as “at least one of A, B, or C, etc.” are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art. For example, “a system having at least one of A, B, or C” should include but is not limited to systems having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc.

[0030] Back-contact cells have the characteristic of arranging both the positive electrode and the negative electrode on the back of the cell, which can reduce the coverage area of ​​the metal electrode on the front of the cell and have higher energy conversion efficiency.

[0031] For example, a cell based on n-type silicon has a p-type doped region and an n-type doped region arranged parallel and spaced apart on its back surface. The polarity of the first electrode (i.e., the secondary gate) disposed on and connected to the p-type doped region is configured as positive; similarly, the polarity of the first electrode disposed on and connected to the n-type doped region is configured as negative.

[0032] The first electrodes (i.e., auxiliary grids) of different polarities (i.e., positive and negative) need to be connected to the second electrodes (i.e., main grids) and / or welding strips of the same polarity to collect the current collected by the first electrodes. In order to insulate the first electrode from the second electrodes and / or welding strips of different polarities, the first electrode needs to be configured as multiple first electrode segments spaced apart so that the first gap formed between two adjacent first electrode segments allows the welding strip and / or second electrode to pass through. If there are too many first gaps formed by adjacent first electrode segments in the first electrode, the effective collection length of the first electrode will be shorter; if there are too few first gaps, the length of each first electrode segment will be too long. Therefore, setting too many or too few first gaps is not conducive to current collection.

[0033] To this end, based on the same inventive concept, how to provide a back-contact cell string and photovoltaic module, so that through the design of the first electrode, the first electrode has a longer effective collection length, and the welding of the first electrode and the welding strip is not prone to short circuit, so as to more effectively prevent leakage, has become a technical problem that needs to be solved urgently.

[0034] FIG1 is a schematic structural diagram of a back-contact battery string according to an exemplary embodiment of the present application.

[0035] According to a back-contact battery string provided by the present application, as shown in FIG1 , it includes a plurality of battery cells 1 and a plurality of first electrodes 3. Each battery cell 1 has a first side and a second side that are orthogonal to each other. Each first electrode 3 of the plurality of first electrodes 3 extends in a direction parallel to the first side, and the plurality of first electrodes 3 are arranged at equal intervals on the back side of the battery cell 1 in a direction parallel to the second side, and each first electrode 3 includes a plurality of first electrode segments arranged at intervals. The ratio of the length of the first electrode 3 to the length of the first side is greater than 98%, and the ratio of the sum of the first gaps between the plurality of first electrode segments of each first electrode 3 to the length of the first electrode 3 is less than or equal to 6%.

[0036] In an exemplary embodiment, as shown in FIG1 , the length of the first electrode 3 is represented by the distance between the longitudinal ends of the first electrode 3 (i.e., the left and right ends as shown in FIG1 ). Specifically, it includes the sum of the lengths of each first electrode segment and the first gap formed between each adjacent first electrode segment that constitutes the first electrode 3. In other words, the length of each first electrode 3 includes the sum of the lengths of the multiple first electrode segments it comprises and the first gaps between the multiple first electrode segments it comprises.

[0037] In this embodiment, the length of the first electrode 3 is configured to be greater than 98% of the length of the first side, giving the first electrode 3 a longer effective collection length. The ratio of the sum of the first gaps between the multiple first electrode segments of each first electrode 3 to the length of the first electrode is set to be less than or equal to 6%, further extending the effective collection length of the first electrode and reducing the risk of short circuits between the first electrode and the welding ribbon, effectively preventing leakage. This integrated design of the first electrode segment length and the first gap width facilitates the collection of current generated by the cell.

[0038] According to an embodiment of the present application, as shown in FIG1 , the back-contact cell string further includes a plurality of second electrodes, each of which extends parallel to the second side. The second electrode passes through a first gap formed by two adjacent first electrode segments of a first electrode 3 having a different polarity from the second electrode, and is connected to a first electrode segment of a first electrode 3 having the same polarity as the second electrode.

[0039] In an illustrative embodiment, as shown in FIG1 , the battery cell 1 includes but is not limited to being configured as a substantially rectangular structure. Specifically, the battery cell 1 includes a first side (i.e., a long side) and a second side (i.e., a short side) as shown in FIG1 . Furthermore, the length of the first side (i.e., a long side) of each battery cell 1 includes but is not limited to being configured as any value between 180 mm and 190 mm, and the length of the second side (i.e., a wide side) includes but is not limited to being configured as any value between 91 mm and 95 mm. It should be understood that the embodiments of the present application are not limited thereto.

[0040] For example, the length of the second side may be configured to be any value between 102 mm and 110 mm.

[0041] In an illustrative embodiment, as shown in FIG1 , a first electrode 3 (i.e., a sub-grid) and a second electrode (i.e., a main grid, which is blocked by the welding strip 2 and is therefore not shown in the figure) are arranged on the back side of the battery cell (i.e., the side facing the viewing angle as shown in FIG1 ). In detail, the first electrode 3 is extended in a direction parallel to the first side (the left-right direction as shown in FIG1 ), and the second electrode is extended in a direction parallel to the second side (the up-down direction as shown in FIG1 ). Furthermore, the corresponding first electrode 3 includes a first electrode A31 and a first electrode B32 with different polarities (i.e., the first electrode A is a positive sub-grid, and the first electrode B is a negative sub-grid; or the first electrode A is a negative sub-grid, and the first electrode B is a positive sub-grid), and the second electrode passes through the first electrode A31 of a different polarity in a direction orthogonal to the first electrode 3, and is connected to the middle of the first electrode B32 of the same polarity.

[0042] In an illustrative embodiment, a plurality of pads (not shown in the figure) are uniformly spaced on the second electrode along a direction parallel to the second side (the up and down direction as shown in FIG1 ). In detail, the first electrode 3 is suitable for connecting to the pad or to the second electrode between adjacent pads. Furthermore, the pad includes but is not limited to being configured as a rectangle, polygon, circle, ellipse, runway or any other shape. Wherein, the first electrode 3 and / or the second electrode (including the pad) include but are not limited to being printed on the battery cell 1 through a corresponding screen.

[0043] In this embodiment, the second electrode (i.e., main grid) disposed on the cell 1 is adapted to collect the current collected by the first electrode 3 (i.e., auxiliary grid). Furthermore, the plurality of second electrodes spaced apart on the cell 1 can effectively prevent warping of the cell 1. It should be understood that the embodiments of the present application are not limited to this embodiment.

[0044] For example, the back contact cell can also be configured as a busbar-less cell structure.

[0045] In an embodiment of a busbar-less battery structure, the first electrode 3 is directly connected to the welding ribbon 2 (i.e., the second welding ribbon 22 shown in FIG1 ), thereby collecting the current collected by the first electrode 3 directly through the welding ribbon 2. The welding ribbon 2 also connects different battery cells 1 in series (e.g., in series). This eliminates the need for printing the slurry used for the second electrode (i.e., busbar), simplifies the screen design used for printing, and reduces the resistance loss caused by the wider portion of the connection between the first electrode 3 and the second electrode. The welding ribbon 2 includes, but is not limited to, a flat welding ribbon.

[0046] According to an embodiment of the present application, which is not shown in the figures, the number of first gaps provided in the first electrodes 3 of the same polarity on the same cell is configured to be 6 to 11.

[0047] According to an embodiment of the present application, not shown in the figure, on the same battery cell, the number of first gaps set in the first electrodes 3 corresponding to the same polarity, and the number of welding strips 2 passing through the first gaps set in the first electrodes 3 are configured to be 11 to 23.

[0048] In an exemplary embodiment, on the same cell, the number of first gaps formed by each first electrode 3 of the same polarity includes, but is not limited to, 6, 7, 8, 9, 10, 11, or any other number. Furthermore, corresponding to the number of first gaps formed by the first electrodes 3 of the same polarity, the number of soldering ribbons 2 can be configured to be any number from 11 to 23, wherein preferably, the number of soldering ribbons 2 can be configured to be twice the number of first gaps of the first electrodes 3 of the same polarity (i.e., if the first electrodes form n first gaps, then 2n soldering ribbons 2 are configured).

[0049] For example, if n=6, 12 welding ribbons (i.e. 12BB) can be configured;

[0050] For another example, if n=11, 22 welding ribbons (ie, 22BB) can be configured.

[0051] It should be understood that the embodiments of the present application are not limited thereto. The number of solder strips 2 can also be configured to be twice the number of first gaps of the first electrodes 3 of the same polarity, with one increase or decrease (i.e., if the first electrodes 3 form n first gaps, then 2n±1 solder strips 2 are configured).

[0052] For example, if n=6, 11 or 13 welding ribbons (i.e., 11BB or 13BB) can be configured;

[0053] For another example, if n=11, 21 or 23 welding ribbons (ie, 21BB or 23BB) can be configured.

[0054] Preferably, the number of first gaps of the first electrodes 3 of the same polarity may be 8 or 9 (ie, n=8 or 9), and the number of welding strips 2 may be 15 or 19 (ie, 15BB or 19BB).

[0055] According to an embodiment of the present application, as shown in FIG1 , the battery string further includes welding ribbons 2. Each welding ribbon 2 extends in a direction parallel to the second side, passes through a first gap formed by two adjacent first electrode segments of a first electrode 3 of one polarity, and connects to a first electrode segment of a first electrode 3 of the other polarity. In the direction parallel to the first side, the ratio of the width of the first gap through which the welding ribbon 2 passes to the width of the welding ribbon 2 is configured to be 1.2 to 2.

[0056] In a preferred embodiment, the number of first gaps in the first electrodes 3 of the same polarity is configured as 9 (i.e., n=9), and the number of solder strips 2 is configured as 18 (i.e., 18BB). Specifically, the width of the first gap provided by the first electrode 3 includes, but is not limited to, being configured as 0.8mm to 1.2mm (i.e., d1 = 0.8mm to 1.2mm as shown in FIG1 ); the width of the solder strip 2 includes, but is not limited to, being configured as 0.6mm (i.e., w = 0.6mm as shown in FIG1 ). Furthermore, the ratio of the width of the first gap through which the solder strip 2 passes to the width of the solder strip 2 is configured as 1.2 / 0.6 to 0.8 / 0.6 (i.e., d1 / w = 2 to 1.33). Furthermore, the length of the first electrode 3 includes, but is not limited to, being configured as 180.328mm (correspondingly, the length of the first electrode 3 should be greater than 98% of the length of the first side and less than 100%).

[0057] In such an embodiment, based on the above design, the number of first gaps of the first electrodes 3 of the same polarity is configured to be 9, and the width of each first gap is configured to be 1.2 mm, so that the ratio of the sum of the first gaps between the multiple first electrode segments of the first electrode 3 to the length of the first electrode 3 (i.e., L = 180.328 mm) is less than or equal to 6% (i.e., n*d1 / L = 5.9%).

[0058] According to an embodiment of the present application, as shown in FIG1 , on the same cell, the ratio of the sum of the first gaps between the multiple first electrode segments of the first electrodes 3 of different polarities to the length of the first electrodes 3 of corresponding polarities is configured to be different.

[0059] According to an embodiment of the present application, as shown in FIG1 , the ratio of the sum of the first gaps between the multiple first electrode segments of the first electrode 3 configured as the positive electrode to the length of the first electrode 3 configured as the positive electrode is greater than the ratio of the sum of the first gaps between the multiple first electrode segments of the first electrode 3 configured as the negative electrode to the length of the first electrode 3 configured as the negative electrode.

[0060] In an exemplary embodiment, the first electrode A31 and the first electrode B32 are configured as a positive sub-grid and a negative sub-grid, respectively. Specifically, the number of first gaps provided in the positive sub-grid and the negative sub-grid can be configured to be the same. Furthermore, the lengths of the positive sub-grid and the negative sub-grid can be configured to be equal. Furthermore, the width of the first gap formed by the positive sub-grid can be greater than the width of the first gap formed by the negative sub-grid (i.e., n*d1+ / L>n*d1- / L).

[0061] In such an embodiment, in response to the characteristic of a larger n-type doping region configured in the back-contact battery, under the premise that the lengths of the first electrodes 3 of different polarities are roughly the same and the number of configured first gaps is the same, the width of the first gap can be reduced so that the negative electrode sub-grid has a larger effective collection length, so that the current will not be too concentrated when passing through the negative electrode sub-grid.

[0062] According to an embodiment of the present application, as shown in FIG1 , the number of solder strips 2 is configured as an odd number, and the numbers of first gaps provided between two adjacent first electrodes 3 with different polarities on the same cell 1 are different.

[0063] In an exemplary embodiment, as shown in Figure 1, the number of welding strips 2 includes but is not limited to being set to 5 (i.e., an odd number), then the number of first gaps set by the two first electrodes A31 is 4, and the number of first gaps set by the two first electrodes B32 with different polarities from the first electrode A31 is 3.

[0064] According to an embodiment of the present application, as shown in FIG1 , the number of first gaps provided between two adjacent first electrodes 3 with different polarities on the same cell 1 differs by 1.

[0065] According to an embodiment of the present application, not shown in the figures, the welding ribbons 2 are configured in an even number, and the number of first gaps set between two adjacent first electrodes 3 with different polarities on the same battery cell 1 is the same.

[0066] In another exemplary embodiment, not shown in the figures, the number of welding ribbons 2 includes but is not limited to 4 (i.e., an even number), and the number of first gaps provided by the two first electrodes A31 having the same polarity is 2, and the number of first gaps provided by the two first electrodes B32 having the same polarity is 2. It should be understood that the above embodiment is exemplary, and the number of welding ribbons 2 and the number of first gaps provided by the first electrodes 3 can be set to any number that meets the design requirements of the back-contact battery.

[0067] In back-contact cells, the interconnections between the cell elements 1 are often achieved through the soldering points of the cell electrodes connected in series with the soldering ribbons 2. During lamination, the first electrode 3 (i.e., the secondary grid) and / or the second electrode (i.e., the main grid) form a cell string. Sufficient solder (such as tin or other bonding material) is required when soldering the soldering ribbons 2 to the soldering points to maintain the reliability of the soldering position. However, excessive solder may flow onto adjacent first electrodes 3 of different polarity during welding, creating a risk of short circuits. Therefore, a corresponding insulating layer is required to insulate the first electrodes 3 from the soldering ribbons 2.

[0068] FIG. 2 is a partial cross-sectional view of a portion A of the back-contact cell string of the exemplary embodiment shown in FIG. 1 .

[0069] According to an embodiment of the present application, as shown in FIG2 , the back-contact cell string further includes an insulating layer 4 made of an insulating material, and the insulating layer 4 covers both ends of the first electrode segment.

[0070] According to an embodiment of the present application, as shown in FIG2 , at one end of the first electrode segment close to the welding ribbon 2 , the thickness of the insulating layer 4 covering the end of the first electrode segment decreases toward the welding ribbon 2 .

[0071] In an illustrative embodiment, as shown in FIG2 , the insulating layer 4 includes, but is not limited to, being made of insulating glue (e.g., green glue). Specifically, the insulating layer 4 at either end of the first electrode segment has two ends, the end of the insulating layer 4 close to the adjacent welding ribbon 2 being the distal end, and the end of the insulating layer 4 away from the adjacent welding ribbon 2 being the proximal end. The thickness of the distal end of the insulating layer 4 (the right end of the insulating layer 4 on the left and the left end of the insulating layer 4 on the right as shown in FIG2 ) is configured to be less than the thickness of the proximal end of the insulating layer 4 (the left end of the insulating layer 4 on the left and the right end of the insulating layer 4 on the right as shown in FIG2 ). Furthermore, the thickness of the insulating layer 4 is configured to gradually decrease from the proximal end to the distal end.

[0072] In such an embodiment, when printing the solder ribbon 2 and soldering the solder ribbon 2 (i.e., the second solder ribbon 22 shown in FIG. 2 ) to the first electrode 3 (i.e., the first electrode A31 shown in FIG. 2 ) using solder 5 (e.g., tin solder), due to the precision limitations of the equipment used (e.g., a machine and / or welding machine), it is inevitable that the solder ribbon 2 and / or solder 5 will be offset (as shown in FIG. 2 ) relative to the ideal position (including but not limited to aligning the centerline of the solder ribbon 2 with the centerline of the first gap formed by two adjacent first electrode segments in the orthographic projection along the thickness direction of the cell 1). To this end, the solder 5 (e.g., tin solder) should be applied as much as possible to the side of the first electrode 3 (i.e., the first electrode A31 shown in FIG. 2 ) that is closest to the solder ribbon 2 (i.e., the second solder ribbon 22 shown in FIG. 2 ). However, this also increases the consumption of insulating material used to prepare the insulating layer 4, thereby increasing the manufacturing cost of the cell string. To this end, the thickness of the distal end of the insulating layer 4 is set to be smaller than the thickness of the proximal end to compensate for the consumption of insulating material for preparing the insulating layer 4; and the thicker portion of the insulating layer 4 can more effectively prevent the problem of tip breakdown.

[0073] According to an embodiment of the present application, as shown in Figure 2, the ratio of the width of the welding strip 2 to the width of the first gap between the two adjacent first electrode segments through which the welding strip passes is configured to be greater than or equal to 0.5, a second gap is provided between the two insulating layers at the two adjacent ends of the two adjacent first electrode segments forming the first gap through which the welding strip passes, and the ratio of the width of the welding strip 2 to the width of the second gap is configured to be less than or equal to 0.75.

[0074] In an exemplary embodiment, as shown in FIG2 , a back-contact cell is configured as a busbar-less cell structure. Specifically, the ratio of the width of the soldering ribbon 2 (i.e., w as shown in FIG2 ) to the width of the second gap between two adjacent insulating layers 4 through which the soldering ribbon 2 passes (i.e., d2 as shown in FIG2 ) is configured to be less than or equal to 0.75 (i.e., w / d2 ≤ 0.75). Furthermore, the ratio of the width of the soldering ribbon 2 (i.e., w as shown in FIG2 ) to the width of the first gap through which the soldering ribbon 2 passes is configured to be greater than or equal to 0.5 (i.e., w / d1 ≤ 0.5).

[0075] For example, the width of the welding ribbon 2 is configured to be 0.6 mm (ie, w=0.6 mm), and the width of the second gap can be configured to be 0.8 mm to 1.2 mm (ie, d2=0.8 mm to 1.2 mm).

[0076] According to an embodiment of the present application, not shown in the figures, the welding strip 2 is welded to the welding pad provided with the second electrode, and a second gap is provided between the two insulating layers at the two adjacent ends of the two adjacent first electrode segments forming the first gap through which the welding strip passes, and the ratio of the width of the welding strip 2 to the width of the second gap is configured to be 0.6 to 1.2.

[0077] In an illustrative embodiment (not shown), the back-contact cell is configured as a busbar (i.e., second electrode) cell structure. Specifically, the ratio of the width of the solder ribbon 2 (i.e., w) to the width of the second gap between two adjacent insulating layers 4 through which the solder ribbon 2 passes (i.e., d2) is configured to be less than or equal to 1.2 and greater than or equal to 0.6 (i.e., 0.6 ≤ w / d2 ≤ 1.2).

[0078] For example, the width of the welding ribbon 2 is configured to be 0.6 mm (ie, w=0.6 mm), and the width of the second gap can be configured to be 0.55 mm to 1.2 mm (ie, d2=0.55 mm to 1.2 mm).

[0079] In this embodiment, based on the design of the first gap, the second gap, and the width of the solder ribbon, the arranged insulating layer 4 can compensate for the offset position of the solder ribbon 2 and / or the solder 5, so that the solder ribbon 2 and / or the solder 5 overlap the insulating layer 4 on at least one side (the left and right sides as shown in FIG2 ), thereby achieving insulation between the first electrode 3 and the solder ribbon 2, thereby preventing the occurrence of a short circuit. Preferably, the solder ribbon 2 and / or the solder 5 only overlap the insulating layer 4 on one side, so that the solder ribbon 2 does not become too high, thereby avoiding poor contact.

[0080] A photovoltaic assembly provided by the present application, not shown in the figures, includes a plurality of battery strings, and the plurality of battery strings are arranged at intervals.

[0081] In an exemplary embodiment, multiple cell strings are arranged in rows or columns and connected in parallel to form a photovoltaic module. Furthermore, multiple cells 1 in the same cell string are connected in series via welding ribbons 2 .

[0082] It should also be noted that directional terms such as "upper," "lower," "front," "back," "left," and "right" mentioned in the embodiments are merely references to the drawings and are not intended to limit the scope of protection of this application. Throughout the drawings, identical elements are represented by identical or similar reference numerals. Conventional structures or configurations will be omitted where they may cause confusion in understanding this application.

[0083] The embodiments of the present application have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present application. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. The scope of the present application is defined by the appended claims and their equivalents. Without departing from the scope of the present application, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present application.

Claims

1. A back-contact battery string comprising: A plurality of battery cells, each of the battery cells having a first side and a second side that are orthogonal to each other; a plurality of first electrodes, each of which extends in a direction parallel to the first side, and the plurality of first electrodes are arranged at equal intervals in a direction parallel to the second side on the back side of the battery cell, and each of the first electrodes includes a plurality of first electrode segments arranged in a direction parallel to the first side at intervals; The ratio of the length of each first electrode to the length of the first side is greater than 98%, and the ratio of the sum of the first gaps between the multiple first electrode segments of each first electrode to the length of the first electrode is less than or equal to 6%. The length of each first electrode includes the lengths of the multiple first electrode segments included therein and the sum of the first gaps between the multiple first electrode segments included therein.

2. The battery string according to claim 1, wherein: The battery string further includes welding ribbons, each of the welding ribbons extending in a direction parallel to the second side, passing through a first gap formed by two adjacent first electrode segments of the first electrode of one polarity, and connected to a first electrode segment of the first electrode of another polarity; Wherein, along a direction parallel to the first side, a ratio of a width of the first gap through which the welding strip passes to a width of the welding strip is configured to be 1.2-2.

3. The battery string according to claim 2, wherein: The welding strips are configured in an even number, and the number of the first gaps set between two adjacent first electrodes with different polarities on the same battery cell is the same.

4. The battery string according to claim 2, wherein: The number of the welding ribbons is odd, and the numbers of the first gaps provided between two adjacent first electrodes with different polarities on the same battery cell are different.

5. The battery string according to claim 4, wherein: On the same cell, the number of the first gaps provided between two first electrodes with different polarities differs by 1.

6. The battery string according to claim 2, characterized in that: On the same battery cell, the number of the first gaps provided in the first electrodes of the same polarity is configured to be 6 to 11.

7. The battery string according to claim 6, wherein: On the same battery cell, the number of the first gaps provided in the first electrodes of the same polarity is configured to be 11 to 23.

8. The battery string according to any one of claims 2 to 7, wherein: The battery string further includes an insulating layer made of an insulating material, and the insulating layer covers both ends of the first electrode segment.

9. The battery string according to claim 8, wherein: At a position of one end of each first electrode segment close to the welding strip, the thickness of the insulation layer covering the end of the first electrode segment decreases along a direction toward the welding strip.

10. The battery string according to claim 8, wherein: The ratio of the width of the welding strip to the width of the first gap between the two adjacent first electrode segments through which the welding strip passes is configured to be greater than or equal to 0.5, and a second gap is provided between the two insulating layers at the two adjacent ends of the two adjacent first electrode segments forming the first gap through which the welding strip passes, and the ratio of the width of the welding strip to the width of the second gap is configured to be less than or equal to 0.

75.

11. The battery string according to claim 8, wherein: The battery string further includes a plurality of second electrodes, each of the second electrodes extending in a direction parallel to the second side; The second electrode passes through a first gap formed by two adjacent first electrode segments of the first electrode with different polarity, and is connected to the first electrode segment of the first electrode with the same polarity.

12. The battery string according to claim 11, wherein: The welding strip is welded to the welding pad provided on the second electrode, and a second gap is provided between the two insulating layers at two adjacent ends of two adjacent first electrode segments forming a first gap through which the welding strip passes, and the ratio of the width of the welding strip to the width of the second gap is configured to be 0.6 to 1.

2.

13. The battery string according to any one of claims 1 to 7, wherein: On the same battery cell, the ratio of the sum of the first gaps between the plurality of first electrode segments of the first electrodes of different polarities to the length of the first electrodes of corresponding polarities is configured to be different.

14. The battery string according to claim 13, wherein: A ratio of a sum of first gaps between a plurality of first electrode segments of the first electrode configured as a positive electrode to a length of the first electrode configured as a positive electrode is greater than a ratio of a sum of first gaps between a plurality of first electrode segments of the first electrode configured as a negative electrode to the length of the first electrode configured as a negative electrode.

15. A photovoltaic module comprising: A plurality of battery strings according to any one of claims 1 to 14, wherein the plurality of battery strings are arranged at intervals.

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