A back contact cell assembly and photovoltaic system

Abstract

The application relates to the technical field of solar cell pieces, and particularly discloses a back contact cell assembly and a photovoltaic system. The cell assembly comprises a cell piece provided with a plurality of fine grids and a plurality of end bus bars, the same end bus bar is connected with a plurality of fine grids of the same polarity, and the end bus bar comprises an edge bus bar; a welding strip, each end bus bar is electrically connected with the adjacent welding strip of the same polarity, the welding strip comprises an edge welding strip; the edge bus bar and the edge welding strip are electrically connected with each other on the same side in the second direction of the cell piece, the projection of the edge welding strip on the cell piece is staggered with the edge bus bar, and the distance from the edge welding strip to the edge of the cell piece is smaller than the distance from the edge bus bar to the edge of the cell piece. The application can effectively improve the current collection efficiency of the edge area of the cell piece, reduce the output loss of the cell piece, increase the overall output power of the cell assembly, and improve the conversion efficiency.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more particularly to a back-contact battery module and photovoltaic system. Background Technology

[0002] Existing gridless back contact batteries typically include positive and negative fine grids arranged alternately along a first direction. Both the positive and negative fine grids extend along a second direction and are electrically connected to the positive or negative fine grids via solder strips to collect the grid current.

[0003] Compared to the central area of ​​the solar cell in the first direction, the fine grids on both sides of the solar cell in the first direction are more prone to grid breakage during the printing process. In order to avoid the solder ribbon tip from exceeding the edge of the solar cell in the first direction and causing a short circuit, the solder ribbon tip needs to maintain a certain distance from the edge of the solar cell in the first direction. This results in limited current collection in the edge areas on both sides of the solar cell in the first direction, affecting the overall output power of the solar module. Summary of the Invention

[0004] The purpose of this invention is to provide a back-contact battery module and photovoltaic system in light of the existing technology.

[0005] This invention can effectively improve the current collection efficiency in the edge area of ​​the battery cell, reduce the output loss of the battery cell, increase the overall output power of the battery module, and improve the conversion efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] First, the present invention provides a back contact battery assembly, comprising:

[0008] A battery cell has a plurality of fine grids and a plurality of end busbars. The plurality of fine grids are arranged along a first direction and each fine grid extends along a second direction. The first direction and the second direction are intersected. The end busbars are located on at least one side of the battery cell in the first direction. The plurality of end busbars are arranged along the second direction and the same end busbar connects to a plurality of fine grids of the same polarity. The end busbars include edge busbars, and the edge busbars are the end busbars closest to the edge of the battery cell in the second direction.

[0009] The solder strips extend along a first direction, and a plurality of the solder strips are arranged along a second direction on the battery cell. Each of the end busbars is electrically connected to the adjacent solder strips of the same polarity. The solder strips include edge solder strips, which are the solder strips closest to the edge of the battery cell in the second direction among the solder strips connected to the battery cell.

[0010] The edge busbar located on the same side of the second direction of the battery cell is electrically connected to the edge solder strip. The projection of the edge solder strip on the battery cell is offset from the edge busbar, and the distance from the edge solder strip to the edge of the battery cell is less than the distance from the edge busbar to the edge of the battery cell.

[0011] In some embodiments, the distance from the edge busbar to the edge of the battery cell is:

[0012] L = l1 + w + l2

[0013] In the formula, L is the distance from the edge busbar to the edge of the battery cell; l1 is the distance from the edge busbar to the side of the edge solder strip closer to the edge busbar in the second direction, l1 > 0; w is the width of the edge solder strip in the second direction; l2 is the distance from the side of the edge solder strip away from the edge busbar to the edge of the battery cell in the second direction, l2 > 0.

[0014] In some embodiments, 0.2mm ≤ l1 ≤ 1.5mm.

[0015] In some embodiments, 3mm ≤ l2 ≤ 10mm.

[0016] In some embodiments, including:

[0017] A battery string, comprising a plurality of battery cells connected in series along a first direction, and the battery string includes a first battery string and a second battery string arranged adjacent to each other along a second direction;

[0018] The battery cell includes a first battery cell and a second battery cell arranged adjacent to each other along a second direction, wherein the first battery cell is disposed on the first battery string and the second battery cell is disposed on the second battery string;

[0019] On the side where the first battery cell and the second battery cell are close to each other, the distance between the edge solder strips on the first battery cell and the second battery cell is less than the distance between the edge busbars on the first battery cell and the second battery cell.

[0020] In some embodiments, on the side where the first battery cell and the second battery cell are close to each other, the distance between the edge busbars on the first battery cell and the second battery cell is:

[0021] S1=l 11 +w1+l 12 +D1+l 21 +w2+l 22

[0022] In the formula, S1 is the distance between the edge busbars on the side where the first and second battery cells are close to each other; 11 On the first battery cell, l is the distance from the edge busbar to the side of the edge solder strip closer to the edge busbar in the second direction. 11 >0; w1 is the width of the edge solder strip on the first battery cell in the second direction; l 12 The distance from the edge solder strip on the first solar cell to the edge of the solar cell in the second direction away from the edge busbar, l 12 >0; D1 is the distance between the edges of the first and second battery cells that are close to each other, D1>0; 21 On the second battery cell, l is the distance from the edge busbar to the side of the edge solder strip closer to the edge busbar in the second direction. 21 >0; w2 is the width of the edge solder strip on the second battery cell in the second direction; l 22 On the second solar cell, the distance from the side of the edge solder strip away from the edge busbar in the second direction to the edge of the solar cell is l. 22 >0.

[0023] In some embodiments, l 12 +l 22 +D1>6mm.

[0024] In some embodiments, the first battery cell and the second battery cell have an overlapping area on their adjacent sides, and the distance between the edge busbars on the first battery cell and the second battery cell is:

[0025] S2=l 11 +w1+d 12 +D2+l 21 +w2+d 22

[0026] In the formula, S2 is the distance between the edge busbars on the side where the first and second battery cells are close to each other; 11 On the first battery cell, l is the distance from the edge busbar to the side of the edge solder strip closer to the edge busbar in the second direction. 11 >0; w1 is the width of the edge solder strip on the first battery cell in the second direction; d 12 d represents the distance d is the distance from the side of the edge solder strip away from the edge busbar in the second direction on the first battery cell to the overlapping area. 12>0; D2 is the width of the overlapping region in the second direction, D2>0; 21 On the second battery cell, l is the distance from the edge busbar to the side of the edge solder strip closer to the edge busbar in the second direction. 21 >0; w2 is the width of the edge solder strip on the second battery cell in the second direction; d 22 On the second battery cell, the distance from the side of the edge solder strip away from the edge busbar in the second direction to the overlapping area is l. 22 >0.

[0027] In some embodiments, 3mm < d 12 +d 22 +D2<20mm.

[0028] In some embodiments, a busbar is further included, the busbar extending along a second direction and disposed on the battery cell, with an insulating member provided between the busbar and the battery cell;

[0029] The welding strip includes a series welding strip and a bus welding strip. The series welding strip is used to electrically connect adjacent battery cells in the same battery string, and the bus welding strip is used to electrically connect the battery cells and the bus bar.

[0030] The edge solder strip is either the serial solder strip or the bus solder strip.

[0031] In some embodiments, the battery cell includes a third battery cell and a fourth battery cell, the third battery cell being disposed adjacent to the first battery cell in a first direction, and the fourth battery cell being disposed adjacent to the second battery cell in the first direction, the busbar extending from the third battery cell to the fourth battery cell.

[0032] Specifically, on the side where the first battery cell and the second battery cell are close to each other, when the polarities of the edge bus lines on the first battery cell and the second battery cell are opposite, the edge solder strips on the first battery cell and the second battery cell are either the series solder strips or the bus solder strips; when the polarities of the edge bus lines on the first battery cell and the second battery cell are the same, the edge solder strip on either the first battery cell or the second battery cell is the series solder strip, and the edge solder strip on the other is the bus solder strip.

[0033] In some embodiments, in the second direction, each of the end busbars is staggered from the adjacent and same polarity solder strips.

[0034] In some embodiments, the battery cell is further provided with a plurality of pad points, and each of the end busbars is electrically connected to the adjacent and same polarity of the solder strip through the pad point, and in a second direction, the centerline of the pad point is offset from the end busbar connected to it.

[0035] In some embodiments, the end bus line further includes a secondary edge bus line, which is disposed adjacent to the edge bus line and has opposite polarities to the edge bus line. In a second direction, the midline of the pad point connected by the secondary edge bus line falls on the side of the secondary edge bus line away from the edge bus line, and the midline of the pad point connected by the edge bus line falls on the side of the edge bus line away from the secondary edge bus line.

[0036] In some embodiments, a plurality of the end busbars are disposed on both sides of the battery cell in the first direction;

[0037] The welding strip includes a series welding strip for connecting adjacent battery cells in series. The series welding strip extends along a first direction, and a plurality of the series welding strips are arranged along a second direction. The two ends of the series welding strip in the first direction are provided with welding strip ends, and the series welding strip is electrically connected to the end bus line of the same polarity that is adjacent to it in the second direction.

[0038] Wherein, on the same side of the battery cell in the first direction, the distance from the first edge to its adjacent end busbar in the first direction is less than the distance from the end of the solder strip to the first edge in the first direction; the first edge is the edge of the battery cell where the end of the solder strip is located that is closest to the end of the solder strip in the first direction.

[0039] In some embodiments, the fine gate includes a first polarity fine gate and a second polarity fine gate with opposite polarities, the first polarity fine gate and the second polarity fine gate being arranged alternately along the first direction;

[0040] The end busbars include a first polarity end busbar and a second polarity end busbar with opposite polarities. On the same side of the battery cell in the first direction, the first polarity end busbar and the second polarity end busbar are arranged alternately in the second direction.

[0041] The same first polarity end busbar is connected to a plurality of first polarity fine gates, and the same second polarity end busbar is connected to a plurality of second polarity fine gates.

[0042] The present invention also provides a photovoltaic system including the above-described battery module.

[0043] The beneficial effects of this invention are as follows:

[0044] On the one hand, in this invention, an end bus is provided at the edge of the battery cell in the first direction, and several fine grids of the same polarity are connected through the same end bus, increasing the current collection path of the fine grids. When a fine grid has a broken grid, its current can still be collected by the corresponding solder strip through the end bus, thereby improving the current collection efficiency and reliability of the edge region. At the same time, compared with the end of the solder strip, the end bus can extend to a position closer to the edge of the battery cell in the first direction to collect the fine grids located between the end of the solder strip and the edge of the battery cell in the first direction. Thus, by electrically connecting each end bus with its adjacent and same polarity solder strip, it is possible to ensure that the end of the solder strip can maintain a certain distance from the edge of the battery cell in the first direction, and the fine grid current between the end of the solder strip and the edge of the battery cell in the first direction can be collected through the end bus, increasing the fine grid current collection capability of this region and improving the current collection efficiency of the edge region.

[0045] On the other hand, in this invention, the projection of the edge solder strip on the cell is staggered from the edge bus line to reduce stress concentration and microcracks that are easily caused by the stacking of the edge solder strip and the edge bus line at the edge of the cell. The distance from the edge solder strip to the edge of the cell is also made smaller than the distance from the edge bus line to the edge of the cell, shortening the current transmission distance in the edge region of the cell. Compared with the middle region, there is a higher surface state density and defects near the edge of the cell, making recombination more likely. Therefore, compared with placing the edge solder strip at the location of the edge bus line, this invention places the edge solder strip closer to the second direction edge of the cell relative to the edge bus line, which can shorten the current transmission distance of the fine grid near the edge of the cell, reduce recombination, thereby reducing overall output loss and increasing overall output power.

[0046] Therefore, by cooperating with the end busbar and the solder strip, the present invention effectively improves the current collection efficiency in the edge area of ​​the battery cell, reduces the output loss of the battery cell, increases the overall output power of the battery module, and improves the conversion efficiency. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the structure of a back contact battery assembly (end busbar area) according to an embodiment of the present invention.

[0048] Figure 2 for Figure 1 A magnified view of a portion of the image.

[0049] Figure 3 This is a schematic diagram of the structure of the battery cell according to an embodiment of the present invention.

[0050] Figure 4 This is a schematic diagram of the structure of the battery cell and solder strip according to an embodiment of the present invention.

[0051] Figure 5 for Figure 4 A magnified view of part A.

[0052] Figure 6 This is a schematic diagram of the structure of a back contact battery assembly (end busbar area) according to an embodiment of the present invention.

[0053] Figure 7 This is a schematic diagram of the structure of a back contact battery assembly (middle busbar area) according to an embodiment of the present invention.

[0054] Figure 8 This is a schematic diagram of the structure of a back-contact battery assembly (with overlapping areas between adjacent battery strings) according to an embodiment of the present invention.

[0055] Figure 9 for Figure 8 A magnified view of part B.

[0056] Figure 10 This is a schematic diagram of the overall structure of the battery cell according to an embodiment of the present invention.

[0057] Figure 11 This is a schematic diagram of half-cell battery arrangement according to an embodiment of the present invention.

[0058] Figure 12 This is a schematic diagram of half-cell battery arrangement according to an embodiment of the present invention.

[0059] Figure 13 This is a schematic diagram of half-cell battery arrangement according to an embodiment of the present invention.

[0060] Figure 14 This is a schematic diagram of half-cell battery arrangement according to an embodiment of the present invention.

[0061] In the picture:

[0062] Battery cell 1, first battery cell 1A, second battery cell 1B, third battery cell 1C, fourth battery cell 1D;

[0063] Fine grid 11, first polarity fine grid 111, second polarity fine grid 112, end bus line 12, edge bus line 12A, secondary edge bus line 12B, first edge 13, pad point 14;

[0064] Welding strip 2, edge welding strip 2A, secondary edge welding strip 2B, tandem welding strip 21, first tandem welding strip 211, second tandem welding strip 212, busbar welding strip 22;

[0065] First battery string 31, second battery string 32, overlapping area 33;

[0066] Busbar 4, Insulating component 5. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the invention, and should not be construed as limiting the invention. Furthermore, it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0068] In the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" or "a number" means two or more, unless otherwise explicitly specified.

[0069] In the description of this invention, unless otherwise expressly specified and limited, the term "above" or "below" the second feature may include direct contact between the first and second features, or contact between the first and second features not in direct contact but through another feature between them.

[0070] It is understood that the busbar 4 and solder ribbon 2 (e.g., busbar solder ribbon 22, series solder ribbon 21, etc.) themselves do not have polarity. In this invention, for ease of description, the polarity of the busbar 4 and solder ribbon 2 refers to their polarity on a certain battery cell 1. The polarity of the busbar 4 and solder ribbon 2 on a certain battery cell 1 is consistent with the polarity of the grid lines collected on that battery cell 1. Correspondingly, the grid lines with opposite polarity are the grid lines with the opposite polarity to the grid lines collected on that battery cell 1. For example, a certain busbar 4 is electrically connected to the grid lines of the positive electrode on a certain battery cell 1. If the current strip 4 is connected to the positive grid line on the battery cell 1, then the polarity of the current strip 4 on the battery cell 1 is positive, and the corresponding grid line of its opposite polarity is negative. For example, if a certain solder strip 2 is electrically connected to the positive grid line on a certain battery cell 1 and electrically connected to the negative grid line on an adjacent battery cell 1, then the polarity of the solder strip 2 on the battery cell 1 is positive, and the corresponding grid line of its opposite polarity on the battery cell 1 is negative. If the polarity of the solder strip 2 on an adjacent battery cell 1 is negative, then the corresponding grid line of its opposite polarity on the adjacent battery cell 1 is positive.

[0071] First, see Figures 1 to 5 As shown, this invention discloses a back contact battery assembly, comprising:

[0072] The battery cell 1 has a plurality of fine grids 11 and a plurality of end busbars 12. The plurality of fine grids 11 are arranged along a first direction and each fine grid 11 extends along a second direction. The first direction and the second direction are intersected. The end busbars 12 are located on at least one side of the battery cell 1 in the first direction. The plurality of end busbars 12 are arranged along the second direction and the same end busbar 12 connects to a plurality of fine grids 11 of the same polarity. The end busbars 12 include edge busbars 12A. The edge busbars 12A are the end busbars 12 closest to the edge of the battery cell 1 in the second direction of the battery cell 1.

[0073] The welding strip 2 extends along the first direction, and a plurality of welding strips 2 are arranged on the battery cell 1 along the second direction. Each end bus line 12 is electrically connected to the adjacent welding strip 2 of the same polarity. The welding strip 2 includes an edge welding strip 2A, which is the welding strip 2 closest to the edge of the battery cell 1 in the second direction among the welding strips 2 connected to the battery cell 1.

[0074] The edge bus line 12A located on the same side of the second direction of the battery cell 1 is electrically connected to the edge solder strip 2A. The projection of the edge solder strip 2A on the battery cell 1 is offset from the edge bus line 12A, and the distance from the edge solder strip 2A to the edge of the battery cell 1 is less than the distance from the edge bus line 12A to the edge of the battery cell 1.

[0075] On one hand, in this invention, an end bus line 12 is provided at the edge of the battery cell 1 in the first direction. Several fine grids 11 of the same polarity are connected through the same end bus line 12, increasing the current collection path of the fine grids 11. When a fine grid 11 has a broken grid, its current can still be collected by the corresponding solder strip 2 through the end bus line 12, thereby improving the current collection efficiency and reliability of the edge region. At the same time, compared with the end of the solder strip 2, the end bus line 12 can extend to a position closer to the edge of the battery cell 1 in the first direction to collect the fine grids 11 located between the end of the solder strip 2 and the edge of the battery cell 1 in the first direction of the battery cell 1. Thus, by electrically connecting each end bus line 12 with its adjacent and same polarity solder strip 2, it is possible to ensure that the end of the solder strip 2 can maintain a certain distance from the edge of the battery cell 1 in the first direction, and the current of the fine grids 11 between the end of the solder strip 2 and the edge of the battery cell 1 in the first direction can be collected through the end bus line 12, increasing the current collection capability of the fine grids 11 in this region and improving the current collection efficiency of the edge region.

[0076] On the other hand, in this invention, the projection of the edge solder strip 2A on the cell 1 is offset from the edge bus line 12A to reduce stress concentration and microcracks that are easily caused by the stacking of the edge solder strip 2A and the edge bus line 12A at the edge of the cell 1. The distance from the edge solder strip 2A to the edge of the cell 1 is also made smaller than the distance from the edge bus line 12A to the edge of the cell 1, thus shortening the current transmission distance in the edge region of the cell 1. Compared with the middle region, there is a higher surface state density and defects near the edge of the cell 1, making recombination more likely. Therefore, compared with setting the edge solder strip 2A at the location of the edge bus line 12A, this invention sets the edge solder strip 2A closer to the second direction edge of the cell 1 relative to the edge bus line 12A, which can shorten the current transmission distance of the fine grid 11 near the edge of the cell 1, reduce recombination, thereby reducing the overall output loss and increasing the overall output power.

[0077] Therefore, by cooperating with the end busbar 12 and the solder strip 2, the present invention effectively improves the current collection efficiency of the edge region of the battery cell 1, reduces the output loss of the battery cell 1, increases the overall output power of the battery module, and improves the conversion efficiency.

[0078] The solar cell 1 has a first side and a second side arranged opposite to each other. One side is the light-receiving side (usually referred to as the front side of the solar cell 1), and the other side is the back-lighting side (usually referred to as the back side of the solar cell 1). In this specification, the first side is the light-receiving side and the second side is the back-lighting side. The light-receiving side generally refers to the side that receives light. It can be understood that in this embodiment, the fine grid 11 and the end busbar 12 can be provided on the first side and / or the second side, and the solder strip 2 is correspondingly provided on the side of the solar cell 1 where the fine grid 11 and the end busbar 12 are provided.

[0079] Electrical connection methods can include welding, bonding with conductive adhesive, etc., but are not limited to these.

[0080] In some embodiments, see Figures 1 to 5 As shown, the distance from edge busbar 12A to the edge of cell 1 is:

[0081] L = l1 + w + l2

[0082] In the formula, L is the distance from the edge busbar 12A to the edge of the cell 1; l1 is the distance from the edge busbar 12A to the side of the edge strip 2A closer to the edge busbar 12A in the second direction, l1 > 0; w is the width of the edge strip 2A in the second direction; l2 is the distance from the side of the edge strip 2A away from the edge busbar 12A in the second direction to the edge of the cell 1, l2 > 0.

[0083] l2 > 0 ensures that the edge solder strip 2A is a certain distance away from the edge of the cell 1 in the second direction, thus ensuring the welding strength of the edge solder strip 2A. l1 > 0 ensures that the edge bus line 12A and the edge solder strip 2A are staggered in the second direction, thereby reducing stress concentration and microcracks that are easily caused by the stacking of the edge solder strip 2A and the edge bus line 12A at the edge of the cell 1. At the same time, it can shorten the current transmission distance of the fine grid 11 near the edge of the cell 1 in the second direction, reduce recombination, thereby reducing the overall output loss and increasing the overall output power.

[0084] It is understandable that the edge of the battery cell 1 here refers to the edge of the non-beveled area of ​​the battery cell 1, that is, the edge of the battery cell 1 parallel to the first direction.

[0085] In some embodiments, 0.2mm ≤ l1 ≤ 1.5mm.

[0086] l1 should not be too large or too small. On the one hand, if l1 is too small, the distance between the edge bus line 12A and the edge solder strip 2A will be too small. During the preparation process, the edge bus line 12A and the edge solder strip 2A may be on the same straight line due to placement deviation, which will increase the risk of stress concentration and microcracks. On the other hand, if l1 is too large, the current transmission between the edge bus line 12A and the edge solder strip 2A will be longer. If the area of ​​the pad point 14 is too large, it will increase the shading area of ​​the solar cell 1, which will lead to increased optical loss.

[0087] In some embodiments, 3mm ≤ l2 ≤ 10mm.

[0088] l2 should not be too large or too small. On the one hand, if l2 is too small, the edge solder strip 2A is too close to the edge of the cell 1 in the second direction, which is not conducive to the welding of the edge solder strip 2A. At the same time, it is easy to increase the risk of microcracks at the edge of the cell 1 in the second direction. In addition, the production precision requirements are increased, which increases the production difficulty. On the other hand, if l2 is too large, the effect of reducing current output loss is not obvious.

[0089] In some embodiments, see Figure 1 , Figure 2 , Figures 6 to 7 As shown, it includes:

[0090] The battery string has a plurality of battery cells 1 connected in series along a first direction, and the battery string includes a first battery string 31 and a second battery string 32 arranged adjacent to each other along a second direction.

[0091] The battery cell 1 includes a first battery cell 1A and a second battery cell 1B arranged adjacent to each other along the second direction. The first battery cell 1A is disposed on the first battery string 31, and the second battery cell 1B is disposed on the second battery string 32.

[0092] On the side where the first battery cell 1A and the second battery cell 1B are close to each other, the distance between the edge solder strips 2A on the first battery cell 1A and the second battery cell 1B is less than the distance between the edge busbars 12A on the first battery cell 1A and the second battery cell 1B.

[0093] In adjacent battery strings, on the side where the first battery cell 1A and the second battery cell 1B are close to each other, the distance between the edge solder strips 2A on the first battery cell 1A and the second battery cell 1B is smaller than the distance between the edge bus lines 12A on the first battery cell 1A and the second battery cell 1B. This helps to reduce the current output loss between strings and increase the overall output power of the battery module.

[0094] It is understandable that in a battery string, the battery string may include two battery cells 1 connected in series, three battery cells 1 connected in series, or more battery cells 1. The specific number of battery cells 1 that need to be connected in series can be determined according to the actual use.

[0095] In some embodiments, see Figures 1 to 2 As shown, on the side where the first battery cell 1A and the second battery cell 1B are close to each other, the distance between the edge busbars 12A on the first battery cell 1A and the second battery cell 1B is:

[0096] S1=l 11 +w1+l 12 +D1+l 21 +w2+l 22

[0097] In the formula, S1 is the distance between the edge busbars 12A on the side where the first battery cell 1A and the second battery cell 1B are close to each other; 11 The distance l on the first solar cell 1A from the edge busbar 12A to the edge solder strip 2A in the second direction, closer to the edge busbar 12A. 11 >0; w1 is the width of the edge solder strip 2A on the first solar cell 1A in the second direction; l 12 The distance from the edge solder strip 2A on the first solar cell 1A, away from the edge busbar 12A in the second direction, to the edge of the solar cell 1, is l. 12 >0; D1 is the distance between the edges of the first solar cell 1A and the second solar cell 1B that are close to each other, D1>0; 21 The distance from the edge busbar 12A to the edge solder strip 2A on the second cell 1B, in the second direction, is the distance closer to the edge busbar 12A. 21 >0; w2 is the width of the edge solder strip 2A on the second cell 1B in the second direction; l 22The distance from the edge of the edge weld strip 2A on the second cell 1B, away from the edge busbar 12A, to the edge of the cell 1, is l. 22 >0.

[0098] l 12 >0, D1>0, l 22 >0, ensuring that there is an appropriate distance between the edge solder strips 2A of adjacent battery strings on the side closest to each other, reducing the risk of short circuit.

[0099] In some embodiments, l 12 +l 22 +D1 > 6mm, ensuring that the edge solder strips 2A on the side where adjacent battery strings are close to each other have an appropriate distance, reducing the risk of short circuit.

[0100] In some embodiments, see Figures 8 to 9 As shown, there is an overlapping area 33 on the side where the first battery cell 1A and the second battery cell 1B are close to each other. The distance between the edge busbars 12A on the first battery cell 1A and the second battery cell 1B is:

[0101] S2=l 11 +w1+d 12 +D2+l 21 +w2+d 22

[0102] In the formula, S2 is the distance between the edge busbars 12A on the side where the first battery cell 1A and the second battery cell 1B are close to each other; 11 The distance l on the first solar cell 1A from the edge busbar 12A to the edge solder strip 2A in the second direction, closer to the edge busbar 12A. 11 >0; w1 is the width of the edge solder strip 2A on the first solar cell 1A in the second direction; d 12 The distance d is the distance from the edge solder strip 2A on the first solar cell 1A, away from the edge busbar 12A, to the overlapping area 33 in the second direction. 12 >0; D2 is the width of the overlapping region 33 in the second direction, D2>0; 21 The distance from the edge busbar 12A to the edge solder strip 2A on the second cell 1B, in the second direction, is the distance closer to the edge busbar 12A. 21 >0; w2 is the width of the edge solder strip 2A on the second cell 1B in the second direction; d 22 The distance d on the edge solder strip 2A of the second cell 1B, from the side away from the edge busbar 12A in the second direction to the overlapping area 33, is given by d. 22 >0.

[0103] d 12 >0, d22 >0, ensuring that the edge solder strip 2A has a certain distance from the overlapping area, avoiding the risk of hidden cracks and short circuits that are easily caused by the edge solder strip 2A being located in the overlapping area.

[0104] In some embodiments, 3mm < d 12 +d 22 +D2<20mm, ensuring that there is an appropriate distance between the edge solder strips 2A on the side where adjacent battery strings are close to each other, reducing the risk of short circuit.

[0105] For example, d 12 +d 22 +D2 can be 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm or 19.5mm, but is not limited to these.

[0106] In some embodiments, see Figures 1 to 2 and Figure 7 As shown, it also includes a busbar 4, which extends along the second direction and is disposed on the battery cell 1. An insulating member 5 is provided between the busbar 4 and the battery cell 1.

[0107] The welding strip 2 includes a series welding strip 21 and a bus welding strip 22. The series welding strip 21 is used to electrically connect adjacent battery cells 1 in the same battery string, and the bus welding strip 22 is used to electrically connect battery cells 1 and busbar 4.

[0108] Edge solder strip 2A is either serial solder strip 21 or bus solder strip 22.

[0109] Busbar 4 is located on the solar cell 1, which allows the solar module to reserve more space to install the solar cell 1, resulting in a larger effective light-receiving area and higher conversion efficiency. At the same time, when busbar 4 is located on the back of solar cell 1, it can be avoided from being exposed when viewed from the front of solar cell 1, thus improving the overall aesthetics of the solar module.

[0110] Understandably, busbar 4 can be an end busbar 4 or an intermediate busbar 4, as shown in the following figure. Figure 1 and Figure 6 As shown, the end busbar 4 refers to the busbar 4 used to connect at least two battery strings arranged adjacent to each other along the second direction. See [link to relevant documentation]. Figure 7 As shown, the intermediate busbar 4 refers to the busbar 4 used to connect at least two battery strings arranged adjacent to each other along the first direction in parallel.

[0111] In some embodiments, the insulating element 5 may be an insulating strip, which electrically isolates the busbar 4 from the battery cell it is located in, thus preventing short circuits. Preferably, the width of the insulating element 5 in the first direction is greater than the width of the busbar 4, so as to avoid the busbar 4 from contacting the fine grid, solder strip, etc. of the battery cell due to placement errors.

[0112] In some embodiments, see Figure 1 As shown, adjacent battery cells 1 are connected by series bonding strips 21. Specifically, the series bonding strips 21 include a first series bonding strip 211 and a second series bonding strip 212. In a first direction, the first series bonding strip 211 and the second series bonding strip 212 are staggered. In a second direction, the first series bonding strip 211 and the second series bonding strip 212 are staggered. In a battery string, the Nth battery cell 1, the N+1th battery cell 1, and the N+2th battery cell 1 are arranged sequentially along the first direction. Two battery cells 1 (N is a positive integer greater than 1), wherein the positive electrode solder joint / positive electrode grid 11 of the Nth battery cell 1 is connected to the negative electrode solder joint / negative electrode grid 11 of the N+1th battery cell 1 by a plurality of first series solder strips 211 arranged along the second direction, and the positive electrode solder joint / positive electrode grid 11 of the N+1th battery cell 1 is connected to the negative electrode solder joint / negative electrode grid 11 of the N+2th battery cell 1 by a plurality of second series solder strips 212 arranged along the second direction.

[0113] In some embodiments, see Figure 1 , Figure 2 and Figure 6 As shown, the battery cell 1 includes a third battery cell 1C and a fourth battery cell 1D. The third battery cell 1C is arranged adjacent to the first battery cell 1A in a first direction, and the fourth battery cell 1D is arranged adjacent to the second battery cell 1B in a first direction. The busbar 4 extends from the third battery cell 1C to the fourth battery cell 1D, that is, the busbar 4 connects the first battery string 31 and the second battery string 32 in series.

[0114] Specifically, on the side where the first battery cell 1A and the second battery cell 1B are close to each other, when the polarities of the edge busbars 12A on the first battery cell 1A and the second battery cell 1B are opposite, the edge solder strips 2A on the first battery cell 1A and the second battery cell 1B are either series solder strips 21 or busbar solder strips 22; when the polarities of the edge busbars 12A on the first battery cell 1A and the second battery cell 1B are the same, the edge solder strip 2A on either the first battery cell 1A or the second battery cell 1B is a series solder strip 21, and the edge solder strip 2A on the other is a busbar solder strip 22.

[0115] In some embodiments, in the second direction, the end busbar 12 located between the edge busbars 12A on both sides of the battery cell 1 in the second direction is arranged in the same straight line direction as the adjacent and same polarity solder strip 2. That is, at this time, only the edge busbar 12A and the edge solder strip 2A are staggered in the second direction.

[0116] In some embodiments, see Figure 1 , Figures 3 to 4 As shown, preferably, in the second direction, each end busbar 12 is staggered from its adjacent and same polarity solder strip 2.

[0117] The location of the end busbar 12 is inherently prone to stress concentration. If it is placed at the connection point between the solder strip 2 and the battery cell 1, the stress generated during the welding, lamination and other production processes will directly act on the location of the end busbar 12, which will easily superimpose stress and exacerbate the risk of stress concentration. In this embodiment, in the second direction, each end busbar 12 is staggered from its adjacent and same polarity solder strip 2 to reduce stress concentration and avoid the risk of microcracks and fragmentation, so that the battery module has both high conversion efficiency and better long-term reliability.

[0118] In some embodiments, see Figure 1 and Figure 2 As shown, the battery cell 1 is also provided with a number of pad points 14, and each end bus line 12 is electrically connected to its adjacent and same polarity solder strip 2 through the pad point 14. In the second direction, the center line of the pad point 14 is staggered from the end bus line 12 connected to it.

[0119] The pad point 14 enables electrical connection between the end bus 12 and its adjacent same-polarity solder strip 2. The offset setting of the pad point 14 ensures that each end bus 12 is staggered from its adjacent same-polarity solder strip 2. At the same time, the setting of the pad point 14 allows for a certain degree of offset between the solder strip 2 and its adjacent same-polarity end bus 12, which helps to reduce the production accuracy requirements and further improve the long-term reliability and production yield of the battery module.

[0120] In some embodiments, see Figure 1 and Figure 2 As shown, the end bus line 12 also includes a secondary edge bus line 12B, which is arranged adjacent to the edge bus line 12A. The polarities of the secondary edge bus line 12B and the edge bus line 12A are opposite. In the second direction, the centerline of the pad point 14 connected to the secondary edge bus line 12B falls on the side of the secondary edge bus line 12B away from the edge bus line 12A, and the centerline of the pad point 14 connected to the edge bus line 12A falls on the side of the edge bus line 12A away from the secondary edge bus line 12B.

[0121] By setting the aforementioned edge structure, the same battery graphic design can be adapted to different layouts as needed, which is highly versatile, helps to simplify the production process, improve line change efficiency, reduce the complexity of warehouse management and inventory costs of battery cell 1, and achieve cost reduction and efficiency improvement.

[0122] Specifically, taking the first battery string 31 and the second battery string 32 connected in series as an example:

[0123] See Figures 10 to 13 As shown, when the first battery string 31 and the second battery string 32 are close to each other, and need to be connected to the busbar 4 via the edge solder strip 2A of the first battery cell 1A and the edge solder strip 2A of the second battery cell 1B, then both the edge solder strip 2A of the first battery cell 1A and the edge solder strip 2A of the second battery cell 1B are busbars 22, and their polarities are opposite. In this case, the first battery cell 1A and the second battery cell 1B can be a single piece (see...). Figure 10 After cutting it into two halves (first half 151, second half 152), the first half 151 and the second half 152 can be arranged in the same direction along the second direction (see...). Figure 11 Alternatively, two first halves 151 or two second halves 152 can be laid out in the same direction along the second direction (see...). Figure 12 and Figure 13 That's all.

[0124] See Figure 10 and Figure 14 As shown, when the first battery string 31 and the second battery string 32 are close to each other, and need to be connected to the busbar 4 via the edge solder strip 2A of the first battery cell 1A and the secondary edge solder strip 2B of the second battery cell 1B, then both the edge solder strip 2A of the first battery cell 1A and the secondary edge solder strip 2B of the second battery cell 1B are busbars 22, and their polarities are opposite. Correspondingly, the edge solder strip 2A of the first battery cell 1A and the edge solder strip 2A of the second battery cell 1B have the same polarity. At this time, the first battery cell 1A and the second battery cell 1B can be a single piece (see...). Figure 10 After cutting it into two halves (the first half 151 and the second half 152), rotate the first half 151 by 180°, and keep the second half 152 in its original direction. That is, the two halves can be arranged in opposite directions along the second direction.

[0125] In some embodiments, a plurality of end busbars 12 are disposed on both sides of the battery cell 1 in a first direction;

[0126] The welding strip 2 includes a series welding strip 21 for connecting adjacent battery cells 1 in series. The series welding strip 21 extends along a first direction, and a plurality of series welding strips 21 are arranged along a second direction. The two ends of the series welding strip 21 in the first direction are provided with welding strip 2 ends, and the series welding strip 21 is electrically connected to the end bus line 12 of the same polarity that is adjacent to it in the second direction.

[0127] Wherein, on the same side of the battery cell 1 in the first direction, the distance from the first edge 13 to its adjacent end busbar 12 in the first direction is less than the distance from the end of the solder strip 2 to the first edge 13 in the first direction; the first edge 13 is the edge of the battery cell 1 where the end of the solder strip 2 is located that is closest to the end of the solder strip 2 in the first direction.

[0128] It is understandable that the series welding strip 21 connects adjacent battery cells 1 in the same battery string, and the ends of the two welding strips 2 of the same series welding strip 21 are respectively located on the side of the adjacent battery cell 1 that is far away from each other in the first direction.

[0129] In this embodiment, an end bus line 12 is provided on the battery cell 1 to collect the fine grid 11 at the first edge of the battery cell 1 in the first direction. The distance h1 from the first edge 13 to its adjacent end bus line 12 in the first direction is less than the distance h2 from the end of the solder ribbon 2 to the first edge 13 in the first direction. This ensures that the end of the solder ribbon 21 does not exceed the first edge 13 of the battery cell 1, avoiding risks such as short circuits and microcracks. At the same time, the end bus line 12 can collect the current of the fine grid 11 between the end of the solder ribbon 2 and the first edge 13 on the battery cell 1, increasing the current collection capacity of the fine grid 11 in this area, thereby improving the overall conversion efficiency of the battery module.

[0130] In some embodiments, the fine gate 11 includes a first polarity fine gate 111 and a second polarity fine gate 112 with opposite polarities, and the first polarity fine gate 111 and the second polarity fine gate 112 are arranged alternately along a first direction;

[0131] The end busbar 12 includes a first polarity end busbar and a second polarity end busbar with opposite polarities. On the same side of the battery cell 1 in the first direction, the first polarity end busbar and the second polarity end busbar are arranged alternately in the second direction.

[0132] The same first polarity end busbar is connected to a plurality of first polarity fine gates 111, and the same second polarity end busbar is connected to a plurality of second polarity fine gates 112.

[0133] Understandably, the fine grid 11 may have blank areas (not shown in the figure) where the opposite polarity conductive parts such as the end bus line 12, solder strip 2, and pad point are located, where the fine grid 11 paste is not printed. Insulating adhesive (not shown in the figure) may also be printed near these locations to electrically isolate them from the opposite polarity conductive parts. The above-mentioned electrical isolation structure can be found in the prior art and will not be described in detail here.

[0134] The present invention also provides a photovoltaic system including the above-described battery module.

[0135] In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0136] In the description of this specification, references to terms such as "some embodiments," "exemplary," "example," or "for example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0137] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A back-contact battery assembly, characterized in that, include: A battery cell has a plurality of fine grids and a plurality of end busbars. The plurality of fine grids are arranged along a first direction and each fine grid extends along a second direction. The first direction and the second direction are intersected. The end busbars are located on at least one side of the battery cell in the first direction. The plurality of end busbars are arranged along the second direction and the same end busbar connects to a plurality of fine grids of the same polarity. The end busbars include edge busbars, and the edge busbars are the end busbars closest to the edge of the battery cell in the second direction. The solder strips extend along a first direction, and a plurality of the solder strips are arranged along a second direction on the battery cell. Each of the end busbars is electrically connected to the adjacent solder strips of the same polarity. The solder strips include edge solder strips, which are the solder strips closest to the edge of the battery cell in the second direction among the solder strips connected to the battery cell. The edge busbar located on the same side of the second direction of the battery cell is electrically connected to the edge solder strip. The projection of the edge solder strip on the battery cell is offset from the edge busbar. The distance from the edge solder strip to the corresponding side edge of the battery cell in the second direction is less than the distance from the edge busbar to the corresponding side edge of the battery cell in the second direction.

2. The back contact battery assembly according to claim 1, characterized in that, The distance from the edge busbar to the corresponding side edge of the battery cell in the second direction is: L = l1 + w + l2 In the formula, L is the distance from the edge busbar to the corresponding side edge of the battery cell in the second direction; l1 is the distance from the edge busbar to the side of the edge solder strip closer to the edge busbar in the second direction, l1 > 0; w is the width of the edge solder strip in the second direction; l2 is the distance from the side of the edge solder strip away from the edge busbar in the second direction to the corresponding side edge of the battery cell in the second direction, l2 > 0.

3. A back-contact battery assembly according to claim 2, characterized in that, 0.2mm≤l1≤1.5mm.

4. A back-contact battery assembly according to claim 2, characterized in that, 3mm≤l2≤10mm.

5. A back-contact battery assembly according to claim 1, characterized in that, include: A battery string, comprising a plurality of battery cells connected in series along a first direction, and the battery string includes a first battery string and a second battery string arranged adjacent to each other along a second direction; The battery cell includes a first battery cell and a second battery cell arranged adjacent to each other along a second direction, wherein the first battery cell is disposed on the first battery string and the second battery cell is disposed on the second battery string; On the side where the first battery cell and the second battery cell are close to each other, the distance between the edge solder strips on the first battery cell and the second battery cell is less than the distance between the edge busbars on the first battery cell and the second battery cell.

6. A back-contact battery assembly according to claim 5, characterized in that, On the side where the first and second battery cells are close to each other, the distance between the edge busbars on the first and second battery cells is: S1=1 11 +w1+l 12 +D1+l 21 +w2+l 22 In the formula, S1 is the distance between the edge busbars on the side where the first and second battery cells are close to each other; 11 On the first battery cell, l is the distance from the edge busbar to the side of the edge solder strip closer to the edge busbar in the second direction. 11 >0; w1 is the width of the edge solder strip on the first battery cell in the second direction; l 12 The distance l on the first solar cell, from the side of the edge solder strip away from the edge busbar in the second direction to the corresponding side edge in the second direction of the solar cell. 12 >0; D1 is the distance between the edges of the first and second battery cells that are close to each other, D1>0; 21 On the second battery cell, l is the distance from the edge busbar to the side of the edge solder strip closer to the edge busbar in the second direction. 21 >0; w2 is the width of the edge solder strip on the second battery cell in the second direction; l 22 On the second battery cell, the distance from the side of the edge solder strip away from the edge busbar in the second direction to the corresponding side edge in the second direction of the battery cell is l. 22 >0.

7. A back-contact battery assembly according to claim 6, characterized in that, l 12 +l 22 +D1>6mm。 8. A back-contact battery assembly according to claim 5, characterized in that, The first and second battery cells have an overlapping area on their adjacent sides, and the distance between the edge busbars on the first and second battery cells is: S2=l 11 +w1+d 12 +D2+l 21 +w2+d 22 In the formula, S2 is the distance between the edge busbars on the side where the first and second battery cells are close to each other; 11 On the first battery cell, l is the distance from the edge busbar to the side of the edge solder strip closer to the edge busbar in the second direction. 11 >0; w1 is the width of the edge solder strip on the first battery cell in the second direction; d 12 d represents the distance d is the distance from the side of the edge solder strip away from the edge busbar in the second direction on the first battery cell to the overlapping area. 12 >0; D2 is the width of the overlapping region in the second direction, D2>0; 21 On the second battery cell, l is the distance from the edge busbar to the side of the edge solder strip closer to the edge busbar in the second direction. 21 >0; w2 is the width of the edge solder strip on the second battery cell in the second direction; d 22 On the second battery cell, d is the distance from the side of the edge solder strip away from the edge busbar in the second direction to the overlapping area. 22 >0.

9. A back-contact battery assembly according to claim 8, characterized in that, 3mm<d 12 +d 22 +D2<20mm。 10. A back-contact battery assembly according to claim 5, characterized in that, It also includes a busbar, which extends along a second direction and is disposed on the battery cell, with an insulating element between the busbar and the battery cell; The welding strip includes a series welding strip and a bus welding strip. The series welding strip is used to electrically connect adjacent battery cells in the same battery string, and the bus welding strip is used to electrically connect the battery cells and the bus bar. The edge solder strip is either the serial solder strip or the bus solder strip.

11. A back-contact battery assembly according to claim 10, characterized in that, The battery cell includes a third battery cell and a fourth battery cell. The third battery cell is disposed adjacent to the first battery cell in a first direction, and the fourth battery cell is disposed adjacent to the second battery cell in the first direction. The busbar extends from the third battery cell to the fourth battery cell. Specifically, on the side where the first battery cell and the second battery cell are close to each other, when the polarities of the edge bus lines on the first battery cell and the second battery cell are opposite, the edge solder strips on the first battery cell and the second battery cell are either the series solder strips or the bus solder strips; when the polarities of the edge bus lines on the first battery cell and the second battery cell are the same, the edge solder strip on either the first battery cell or the second battery cell is the series solder strip, and the edge solder strip on the other is the bus solder strip.

12. A back-contact battery assembly according to claim 1, characterized in that, In the second direction, each of the end busbars is staggered from the adjacent and same polarity solder strips.

13. A back-contact battery assembly according to claim 12, characterized in that, The battery cell is also provided with a number of pad points, and each of the end bus lines is electrically connected to the adjacent and same polarity of the welding strip through the pad point. In the second direction, the center line of the pad point is staggered from the end bus line connected to it.

14. A back-contact battery assembly according to claim 13, characterized in that, The end bus line also includes a secondary edge bus line, which is arranged adjacent to the edge bus line and has opposite polarities to the edge bus line. In the second direction, the midline of the pad point connected by the secondary edge bus line falls on the side of the secondary edge bus line away from the edge bus line, and the midline of the pad point connected by the edge bus line falls on the side of the edge bus line away from the secondary edge bus line.

15. A back-contact battery assembly according to claim 1, characterized in that, Several of the aforementioned end busbars are disposed on both sides of the battery cell in the first direction; The welding strip includes a series welding strip for connecting adjacent battery cells in series. The series welding strip extends along a first direction, and a plurality of the series welding strips are arranged along a second direction. The two ends of the series welding strip in the first direction are provided with welding strip ends, and the series welding strip is electrically connected to the end bus line of the same polarity that is adjacent to it in the second direction. Wherein, on the same side of the battery cell in the first direction, the distance from the first edge to its adjacent end busbar in the first direction is less than the distance from the end of the solder strip to the first edge in the first direction; the first edge is the edge of the battery cell where the end of the solder strip is located that is closest to the end of the solder strip in the first direction.

16. A back-contact battery assembly according to claim 1, characterized in that, The fine grid includes a first polarity fine grid and a second polarity fine grid with opposite polarities, and the first polarity fine grid and the second polarity fine grid are arranged alternately along the first direction; The end busbars include a first polarity end busbar and a second polarity end busbar with opposite polarities. On the same side of the battery cell in the first direction, the first polarity end busbar and the second polarity end busbar are arranged alternately in the second direction. The same first polarity end busbar is connected to a plurality of first polarity fine gates, and the same second polarity end busbar is connected to a plurality of second polarity fine gates.

17. A photovoltaic system, characterized in that, Includes the battery assembly according to any one of claims 1 to 16.

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