Back contact battery and photovoltaic module

Abstract

The invention is applicable to the technical field of solar cells, and provides a back contact battery and a photovoltaic module, the back contact battery comprises a battery piece, a first auxiliary grid and a second auxiliary grid, and the polarity of the first auxiliary grid and the polarity of the second auxiliary grid are different; the first auxiliary grids and the second auxiliary grids are arranged on the back surface of the battery piece and extend along a first direction, the first auxiliary grids and the second auxiliary grids are alternately arranged along a second direction, and the first direction is perpendicular to the second direction; the back surface of the battery piece is provided with a plurality of series connection areas, and the series connection areas are used for collecting current collected by the first auxiliary grid or the second auxiliary grid through a bonding pad; each serial connection area extends along a second direction; the battery piece is provided with a first edge and a second edge which are opposite in the second direction; and the lengths of the bonding pads in partial areas between the first edge and / or the second edge and the center line of the battery piece are gradually reduced in sequence. According to the back contact battery and the photovoltaic module provided by the invention, the welding firmness can be improved, and the risk of poor welding strip connection is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a back contact cell and a photovoltaic module. Background Art

[0002] In the related art, in a solar cell without a main grid back contact, pads of equal length are provided at the positions where the secondary grid and the welding strip are connected. If the pad length is short, local welding failure is more likely to occur, thereby affecting the photoelectric conversion efficiency of the cell; if the pad length is long, the silver paste loss is large, which directly leads to an increase in the cost of the component. The component cost is high, and the effective cell surface area that can be used for photoelectric conversion is reduced, thereby affecting the photoelectric conversion efficiency of the solar cell. Summary of the invention

[0003] The present invention provides a back contact cell and a photovoltaic module, aiming to solve the problem that a larger or smaller pad size affects the photoelectric conversion efficiency of a solar cell.

[0004] The present invention provides a back contact battery, comprising: a battery sheet, a first auxiliary grid and a second auxiliary grid, wherein the first auxiliary grid and the second auxiliary grid have different polarities;

[0005] The first auxiliary grid and the second auxiliary grid are arranged on the back side of the battery cell and extend along a first direction, the first auxiliary grid and the second auxiliary grid are alternately arranged along a second direction, and the first direction is perpendicular to the second direction;

[0006] A plurality of series connection areas are provided on the back of the battery cell, and the series connection areas are used to collect the current collected by the first auxiliary grid or the second auxiliary grid through the welding pad; each series connection area extends along the second direction;

[0007] The battery sheet has a first edge and a second edge opposite to each other in the second direction;

[0008] The lengths of the pads in a partial area between the first edge and / or the second edge and the center line of the battery cell decrease in sequence.

[0009] In some embodiments, there are a first boundary line and a second boundary line between the first edge and the second edge and the midline, respectively;

[0010] The length of the pad between the center line and the first boundary line remains unchanged, the length of the pad between the first boundary line and the first edge increases successively, the length of the pad between the center line and the second boundary line remains unchanged, and the length of the pad between the second boundary line and the second edge increases successively.

[0011] In some embodiments, when at least one adhesive portion is provided in the series connection area, the adhesive portion extends along the second direction, and the length of the pad corresponding to the adhesive portion in the first direction varies based on the width of the adhesive portion in the first direction.

[0012] In some embodiments, the bonding portion is used to bond to the soldering strip, and the width of the bonding portion in the first direction accounts for 15% to 30% of the width of the soldering strip.

[0013] In some embodiments, the plurality of bonding portions are alternately distributed along the second direction on both sides of a center line of the serial connection area.

[0014] In some embodiments, there is a gap between the pad corresponding to the adhesive portion in the first direction and the adhesive portion.

[0015] In some embodiments, the interval between the bonding pad corresponding to the bonding portion in the first direction and the bonding portion is 100 μm to 300 μm.

[0016] In some embodiments, the second boundary and the first boundary are symmetric about the midline.

[0017] In some embodiments, the pads in each serial connection region are symmetrical about the center line.

[0018] In some embodiments, the serial connection area is used to place a soldering ribbon.

[0019] The present invention also provides a photovoltaic module, comprising: a back contact cell as described in any one of the above items.

[0020] The back-contact cell and photovoltaic module provided by the present invention have solder pads of different lengths arranged in the series connection area of ​​the cell sheet, and the length of the solder pads in the partial area between the edge of the cell sheet and the center line has a decreasing trend, which can increase the connection tension between the solder strip and the auxiliary grid near the edge area, improve the firmness of the solder strip welding, reduce the risk of poor solder strip connection due to uneven tension, and ensure that the photoelectric conversion efficiency of the back-contact cell is not affected; on the other hand, the length of the solder pads in the partial area decreases successively, which can reduce the slurry loss without affecting the welding effect, thereby reducing the component cost and improving the photoelectric conversion efficiency of the back-contact cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is one of the structural schematic diagrams of a back contact battery provided by an embodiment of the present invention;

[0022] Figure 2 This is the second structural schematic diagram of the back contact battery provided by the embodiment of the present invention;

[0023] Figure 3This is the third structural schematic diagram of the back contact battery provided by the embodiment of the present invention;

[0024] Figure 4 This is the fourth structural schematic diagram of the back contact battery provided by the embodiment of the present invention;

[0025] Figure 5 It is a schematic diagram of the structure of a photovoltaic module provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0027] Reference to "embodiments" or "implementations" in the present invention means that the specific features, components, or characteristics described in conjunction with the embodiments or implementations may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0028] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] Combine the following Figures 1 to 5 , the back contact cell and photovoltaic module provided by the embodiments of the present invention are described in detail through specific embodiments and their application scenarios.

[0031] Figure 1 FIG. 1 is one of the structural schematic diagrams of the back contact battery provided by the embodiment of the present invention. Figure 1 As shown, the present invention provides a back contact battery, comprising: a battery cell 10, a first auxiliary grid 20 and a second auxiliary grid 30, wherein the first auxiliary grid 20 and the second auxiliary grid 30 have different polarities;

[0032] The first auxiliary grid 20 and the second auxiliary grid 30 are disposed on the back of the battery cell 10 and extend along a first direction. The first auxiliary grid 20 and the second auxiliary grid 30 are alternately arranged along a second direction, and the first direction is perpendicular to the second direction.

[0033] A plurality of series connection areas 40 are provided on the back of the cell 10. The series connection areas 40 are used to collect the current collected by the first sub-grid 20 or the second sub-grid 30 through the pads 50. Each series connection area 40 extends along the second direction.

[0034] The battery cell 10 has a first edge 101 and a second edge 102 opposite to each other in the second direction;

[0035] The length of the pad 50 in the partial area between the first edge 101 and / or the second edge 102 and the center line 103 of the battery cell decreases successively.

[0036] In the embodiment of the present invention, the back contact cell is a busbar-free back contact cell. The cell 10 included in the busbar-free back contact cell can be a whole cell 10, or a half cell, a third cell, or a cell 10 of other proportions divided from a whole cell 10. It should be noted that the drawings provided by the present invention are schematic diagrams and do not limit the specific form of the back contact cell.

[0037] Furthermore, the cell 10 includes a front side and a back side, the front side faces the sun and mainly receives direct sunlight, and the back side faces the mounting surface of the photovoltaic module and mainly receives sunlight reflected by the mounting surface, such as the ground, the roof, etc. In addition, the back side of the cell 10 is also provided with a stacked doping layer and a passivation layer, and the doping layer can establish an ohmic contact with the auxiliary grid.

[0038] A plurality of sub-grids are arranged on the back of the cell 10, including first sub-grids 20 or second sub-grids 30 with different polarities, and the plurality of first sub-grids 20 or second sub-grids 30 are all extended along the first direction and alternately arranged along the second direction, and the second direction intersects the first direction. The spacing between adjacent first sub-grids 20 or second sub-grids 30 may be equal or unequal, which is not specifically limited here.

[0039] It should be noted that the first direction may be the length direction of the secondary grid, that is, Figure 1 and Figure 2 The second direction may be the width direction of the secondary grid, that is, Figure 1 and Figure 2 Of course, in other embodiments, the first direction and the second direction may also be other directions, such as diagonal directions, etc., which are not specifically limited here.

[0040] Several sub-grids can be positive sub-grids or negative sub-grids, and the first sub-grid 20 and the second sub-grid 30 have opposite polarities. For example, if the first sub-grid 20 is a positive sub-grid, the second sub-grid 30 is a negative sub-grid; if the second sub-grid 30 is a positive sub-grid, the first sub-grid 20 is a negative sub-grid.

[0041] like Figure 1 and Figure 2 As shown, there are a plurality of series connection areas 40 on the back side of the solar cell 10, and the plurality of series connection areas 40 may include a first series connection area 401 and a second series connection area 402 for collecting currents of sub-grids of different polarities. The plurality of series connection areas 40 extend along the second direction and intersect with all the first sub-grids 20 and the second sub-grids 30, and the first series connection areas 401 and the second series connection areas 402 are alternately arranged in parallel along the first direction.

[0042] In some embodiments, a pad 50 is provided at the intersection of any series connection area 40 and the first sub-grid 20 or the second sub-grid 30, and the length of the pad 50 does not exceed the width of the series connection area 40, wherein the intersection position is the position where the soldering strip is conductively connected to the first sub-grid 20 or the second sub-grid 30.

[0043] It can be understood that each series connection area 40 collects the current on the auxiliary grid of one polarity. Therefore, in the case where the series connection area 40 collects the current of the first auxiliary grid 20, the pad 50 is set at the intersection of the series connection area 40 and the first auxiliary grid 20, and the pad 50 is not set at the intersection with the second auxiliary grid 30. In the case where the series connection area 40 collects the current of the second auxiliary grid 30, the pad 50 is set at the intersection of the series connection area 40 and the second auxiliary grid 30, and the pad 50 is not set at the intersection with the first auxiliary grid 20.

[0044] The pad 50 extends along the first direction, and the length of the pad 50 refers to the length of the pad 50 in the first direction. The longer the length of the pad 50 is, the greater the welding tension on the welding strip is. The width of the pad 50 is determined based on the spacing between the adjacent first auxiliary grid 20 and the second auxiliary grid 30 and the auxiliary grid width. For example, the width of the pad 50 can be equal to or slightly larger than the width of the first auxiliary grid 20 or the second auxiliary grid 30, which is not specifically limited here.

[0045] In the embodiment of the present invention, refer to Figure 1 and Figure 2 The first series connection area 401 is used to collect the current of the first sub-gate 20 by setting the pad 50 ; the second series connection area 402 is used to collect the current of the second sub-gate 30 by setting the pad 50 .

[0046] In some embodiments, the serial connection area 40 is used to place solder strips.

[0047] In actual implementation, solder paste is printed on the pad 50, and the solder strip is placed on the pad 50 coated with solder paste. After the solder paste melts, a solder joint is formed between the solder strip and the pad 50, thereby forming a good solder connection. The width of the solder strip does not exceed the width of the series connection area 40, the solder strips extend along the second direction and cross all the sub-grids, and the solder strips of different polarities are alternately arranged in parallel along the first direction.

[0048] Optionally, the width of the soldering strip may be less than or equal to the width of the serial connection area 40 , for example, the width of the serial connection area 40 is 2.1 mm, and the width of the soldering strip is 2.1 mm or 2.0 mm.

[0049] Taking the first sub-grid 20 as the positive sub-grid and the second sub-grid 30 as the negative sub-grid as an example, a positive electrode welding strip can be set in the first series connection area 401 for collecting the current of the first sub-grid 20, and a negative electrode welding strip can be set in the second series connection area 402 for collecting the current of the second sub-grid 30. The positive electrode welding strip is electrically connected to the first sub-grid 20, and the positive electrode welding strip is insulated from the second sub-grid 30, and the negative electrode welding strip is electrically connected to the second sub-grid 30, and the negative electrode welding strip is insulated from the first sub-grid 20.

[0050] In actual implementation, since the first sub-grid 20 and the second sub-grid 30 are arranged alternately, the series connection area 40 collects the current of the sub-grids of one polarity, and the pads 50 are arranged at every sub-grid interval in the series connection area 40 .

[0051] like Figure 1 As shown, the length of the solder pad 50 in the partial area between the first edge 101 and the center line 103 of the battery cell has a decreasing trend, or the length of the solder pad 50 in the partial area between the center line 103 and the second edge 102 has an increasing trend, or the length of the solder pad 50 in the partial area between the first edge 101 and the second edge 102 and the center line 103 of the battery cell has a decreasing trend.

[0052] For example: the length of the solder pad 50 in the partial area from the first edge 101 to the center line 103 of the battery cell can be set to 1.9 mm, 1.6 mm, 1.3 mm, 1.0 mm and 0.7 mm, etc. in sequence along the second direction; the length of the solder pad 50 in the partial area from the center line 103 to the second edge 102 can be set to 0.7 mm, 1.0 mm, 1.3 mm, 1.6 mm and 1.9 mm, etc. in sequence along the second direction.

[0053] In actual implementation, the closer the pad 50 is to the first edge 101 or the second edge 102, the longer the pad 50 is; the closer the pad 50 is to the center line 103, the shorter the pad 50 is. The maximum and minimum lengths of the pad 50 can be set according to the width of the solder strip or actual conditions, and are not specifically limited here.

[0054] In some embodiments, there are first boundary line 104 and second boundary line 105 between first edge 101 and second edge 102 and midline 103 respectively;

[0055] The length of the pad 50 between the center line 103 and the first boundary line 104 remains unchanged, the length of the pad 50 between the first boundary line 104 and the first edge 101 increases successively, the length of the pad 50 between the center line 103 and the second boundary line 105 remains unchanged, and the length of the pad 50 between the second boundary line 105 and the second edge 102 increases successively.

[0056] like Figure 2 As shown, the length of the solder pad 50 from the first edge 101 to the first boundary 104 in the series area 40 shows a decreasing trend, and then the length of the solder pad 50 from the first boundary 104 to the center line 103 remains unchanged; the length of the solder pad 50 from the second boundary 105 to the second edge 102 in the series area 40 shows an increasing trend, and then the length of the solder pad 50 from the second boundary 105 to the center line 103 remains unchanged.

[0057] For example, the length of the pad 50 from the first edge 101 to the first boundary 104 can be set to 1.9 mm, 1.6 mm, 1.3 mm, 1.0 mm and 0.7 mm in descending order; the length of the pad 50 from the first boundary 104 to the center line 103 remains unchanged at 0.7 mm, and the length of the pad 50 from the center line 103 to the second boundary 105 remains unchanged at 0.7 mm; the length of the pad 50 from the second boundary 105 to the second edge 102 can be set to 0.7 mm, 1.0 mm, 1.3 mm, 1.6 mm and 1.9 mm in ascending order, etc. The positions of the first boundary 104 and the second boundary 105 can be set according to actual needs and are not specifically limited here.

[0058] It is understandable that the decreasing trend may be an arithmetic decrease or an arithmetic decrease, and the increasing trend may be an arithmetic increase or an arithmetic increase, which is not specifically limited here. For example, the length of the pad 50 may be: L 1 , L 2 , L 3 , L 4 , L 5 and L 6 , if there is a decreasing trend, then L 1 <L 2 <L3 <L 4 <L 5 <L 6 ; If there is an increasing trend, then L 1 >L 2 >L 3 >L 4 >L 5 >L 6 ; or it can be L 1 =L 2 <L 3 =L 4 <L 5 =L 6 ; It can also be L 1 =L 2 =L 3 <L 4 <L 5 =L 6 wait.

[0059] In actual implementation, the length variation trend of the solder pads 50 in the plurality of serial connection regions 40 in the battery cell 10 may be Figure 1 You can also use Figure 2 You can also use Figure 1 Ways and Figure 2 The combination is arranged in a manner not specifically limited here.

[0060] The combination setting can be that the serial connection areas 40 corresponding to the solder strips of different polarities respectively use solder pads 50 with different length variation trends, that is, one serial connection area 40 uses Figure 1 The adjacent series connection area 40 adopts Figure 2 It can also be used in the same serial area 40 Figure 1 Ways and Figure 2 For example, the length of the pad from the first edge 101 to the center line 103 in the series connection area 40 decreases successively, and the length of the pad from the second edge 102 to the center line 103 first remains unchanged and then increases, etc., which is not specifically limited here.

[0061] It should be noted that during the welding process, the stress and tension at the first edge 101 and the second edge 102 are more concentrated, so the welding tension required for the welding strip close to the edge is larger, and it is more likely to have problems with cold soldering or poor connection. In this case, the length of the welding pad 50 close to the first edge 101 or the second edge 102 can be set to be relatively larger, while the stress and tension near the center line 103 are more dispersed, and cold soldering is less likely to occur in this part of the welding strip. In this case, the length of the welding pad 50 close to the center line 103 can be set to be relatively smaller.

[0062] The back-contact battery provided by the embodiment of the present invention has solder pads of different lengths in the series connection area of ​​the battery cell, and the length of the solder pads in the partial area between the edge of the battery cell and the center line shows a decreasing trend, which can increase the connection tension between the solder strip and the auxiliary grid near the edge area, improve the firmness of the solder strip welding, reduce the risk of poor solder strip connection due to uneven tension, and ensure that the photoelectric conversion efficiency of the back-contact battery is not affected. On the other hand, the length of the solder pads in some areas decreases successively, which can reduce the slurry loss without affecting the welding effect, thereby reducing the component cost and improving the photoelectric conversion efficiency of the back-contact battery.

[0063] In some embodiments, the second boundary 105 and the first boundary 104 are symmetrical about the center line 103 .

[0064] In actual implementation, the second boundary 105 and the first boundary 104 can be symmetrical about the center line 103, so that the number of pads 50 between the first boundary 104 and the center line 103 is equal to the number of pads 50 between the second boundary 105 and the center line 103, and the length of the pads 50 from the second boundary 105 to the first boundary 104 is also equal, so that the tension of the welding ribbon corresponding to the second boundary 105 to the first boundary 104 is more uniform, and the stability of the welding ribbon connection is improved. Of course, in other embodiments, the second boundary 105 and the first boundary 104 can also be set asymmetrically, which is not specifically limited here.

[0065] In some embodiments, the pads 50 in each serial connection region 40 are symmetrical about the centerline position 103 .

[0066] In actual implementation, the change trend of the solder pad length from the first edge 101 to the center line 103 in the series area 40 is the same as the change trend of the solder pad length from the second edge 102 to the center line 103, so that the solder strip tension corresponding to the series area 40 is symmetrically and evenly distributed, which can effectively avoid the occurrence of cold solder joints in the subsequent welding process.

[0067] In some embodiments, when at least one adhesive portion 60 is disposed in the serial connection area 40 , the adhesive portion 60 extends along the second direction, and the length of the pad 50 corresponding to the adhesive portion 60 in the first direction varies based on the width of the adhesive portion 403 in the first direction.

[0068] like Figure 3 As shown, at least one bonding portion 60 is provided in the serial connection area 40. The bonding portion 60 is used to bond with the bonded object by dispensing. The embodiment of the present invention does not specifically limit the type of adhesive corresponding to the dispensing, for example, it can be UV glue, etc.

[0069] In actual implementation, the overlapping area of ​​the area 70 covered by the adhesive and the serial connection area 40 is the bonding portion 60. In the embodiment of the present invention, glue can be dispensed in at least a portion of the area corresponding to the bonding portion 60. Due to the fluidity of the adhesive itself, part of the adhesive may overflow outside the serial connection area 40, and part of the adhesive is not bonded to the solder strip. Then, the bonding portion 60 and the area where part of the adhesive is not bonded to the solder strip form the area 70. Alternatively, the area 70 can also be the entire glue dispensing area, and the bonding portion 60 is the area where the solder strip is actually covered by the adhesive.

[0070] In actual implementation, the shape, size and number of the adhesive portion 60 can be set according to actual conditions and are not specifically limited here. The shape of the adhesive portion 60 can be elliptical, rectangular, circular or other shapes, the length of the adhesive portion 60 in the second direction can be any length between 2 mm and 5 mm, and the number of the adhesive portions 60 can be 2, 3, 4, 5, 6, 7 or 8, etc.

[0071] In the embodiment of the present invention, the length of the pad 50 corresponding to the bonding portion 60 in the first direction can be adaptively changed according to the shape of the bonding portion 60 and / or the width of the bonding portion 60 in the first direction, which can effectively avoid the phenomenon of cold solder joints during the welding process. The width of the bonding portion 60 in the first direction can be changed according to the shape of the bonding portion 60, for example: if the bonding portion 60 is rectangular, the width of the bonding portion 60 in the first direction remains unchanged; if the bonding portion 60 is elliptical, the width of the bonding portion 60 in the first direction changes along the elliptical arc.

[0072] For example: the wider the width of the adhesive portion 60 in the first direction, the greater the adhesive force provided by the adhesive portion 60, and the smaller the length of the corresponding pad 50 in the first direction; the narrower the width of the adhesive portion 60 in the first direction, the smaller the adhesive force provided by the adhesive portion 60, and the larger the length of the corresponding pad 50 in the first direction.

[0073] For example: if the adhesive portion 60 is a rectangle, the length of the pad 50 corresponding to the adhesive portion 60 in the first direction can be set to the same length, and the center point of this part of the pad 50 can be set on the same straight line; if the adhesive portion 60 is an ellipse, the length of the pad 50 corresponding to the adhesive portion 60 in the first direction can vary along the elliptical arc, and the center point of this part of the pad may not be set on the same straight line.

[0074] It can be understood that the center point of the pad 50 corresponding to the adhesive portion 60 in the first direction is not on the same straight line as the center points of other pads in the area where the adhesive portion 60 is not provided.

[0075] Optionally, the pads 50 corresponding to the adhesive portion 60 in the first direction can be set to the same length or different lengths, and the center points of the pads 50 can be set on the same straight line or different straight lines, which is not specifically limited here.

[0076] Reference Figure 3 , the length of the bonding portion 60 corresponding to the pad 50 in the first direction does not exceed the width of the serial connection area 40. Figure 1 or Figure 2 It can be seen that when the adhesive portion 60 is set in the series connection area 40, the position of the soldering pad 50 corresponding to the adhesive portion 60 in the first direction can be adjusted according to the setting position of the adhesive portion 60, that is, the soldering pad 50 in the area where the adhesive portion 60 is set is shifted to the left or right as a whole, so that the position of the adhesive portion 60 can be reserved, and the length of the soldering pad 50 corresponding to the adhesive portion 60 in the first direction can also keep the original change trend unchanged.

[0077] In some embodiments, the plurality of bonding portions 60 are alternately distributed along the second direction on both sides of the center line of the serial connection area 40 .

[0078] In actual implementation, the number of multiple adhesive portions 60 alternately distributed along the second direction on both sides of the center line of the series connection area 40 can be set to an even number, and then the same number of adhesive portions 60 can be set on both sides of the center line of the series connection area 40, so as to obtain uniform bonding force, and ensure the uniform height of the welding strip, and avoid the problem of cold welding caused by inconsistent welding strip height. If the number of multiple adhesive portions 60 is set to an odd number, the number of adhesive portions 60 set on both sides of the center line of the series connection area 40 will be different, and the bonding force on both sides of the center line of the series connection area 40 will be different. The problem of inconsistent welding strip height may occur during subsequent bonding, resulting in unstable welding of the welding strip, which in turn affects the reliability of the battery.

[0079] In the related art, if the height of the adhesive portion 60 is greater than the height of the solder paste on the pad 50, the soldering tape may not be able to contact the solder paste on the pad 50, resulting in a cold solder joint in the subsequent soldering process. If the height of the adhesive portion 60 is less than the height of the solder paste on the pad 50, the adhesiveness between the soldering tape and the adhesive portion 60 may decrease or even fail to bond while ensuring that the solder paste on the pad 50 is in contact with the solder paste. The number of the multiple adhesive portions 60 provided in the embodiment of the present invention is set to an even number to avoid the problem of inconsistent soldering tape height caused by uneven distribution of adhesive force.

[0080] In some embodiments, there is a gap between the bonding portion 60 and the pad 50 corresponding to the bonding portion 60 in the first direction.

[0081] In actual implementation, the pad corresponding to the adhesive part 60 in the first direction cannot overlap with the adhesive part 60. There is a risk of the adhesive part 60 contacting the pad 50 after dispensing, and a safe distance needs to be set between the two. Therefore, a certain interval can be set between the pad 50 corresponding to the adhesive part 60 in the first direction and the adhesive part 60.

[0082] In some embodiments, the interval between the bonding pad corresponding to the bonding portion 60 and the bonding portion 60 in the first direction is 100 μm to 300 μm.

[0083] Optionally, the interval between the bonding pad corresponding to the bonding portion 60 and the bonding portion 60 in the first direction may be 100 μm, 150 μm, 200 μm, 250 μm or any value in the range of 100 μm to 300 μm, which is not specifically limited herein.

[0084] In some embodiments, the bonding portion 60 is used to bond with the soldering strip, and the width of the bonding portion 60 in the first direction accounts for 15% to 30% of the width of the soldering strip.

[0085] It can be understood that the soldering tape extends along the second direction, the width of the soldering tape refers to the width of the soldering tape in the first direction, the width of the soldering tape is less than or equal to the width of the serial connection area 40, and the length of the soldering pad 50 is less than the width of the soldering tape. The bonding portion 60 is bonded to the soldering tape by dispensing glue, so that the soldering tape is bonded to the battery cell 10.

[0086] For the area where the bonding portion 60 is not provided in the serial connection area 40, the safety distance between the two ends of the pad 50 in the first direction and the two edges of the solder strip in the first direction is 100 μm to 300 μm. For example, if the solder strip is 2 mm, the length of the pad 50 does not exceed 1.9 mm. For example, the length of the pad 50 can be set to 0.7 mm, 0.9 mm, 1.5 mm, or any length between 1.7 mm and 1.9 mm.

[0087] For the region where the adhesive portion 60 is disposed in the serial connection region 40 , the length of the pad 50 corresponding to the adhesive portion 60 in the first direction can be determined according to the width of the adhesive portion 60 and the width of the soldering tape.

[0088] like Figure 4 As shown, taking any pad of the pads 50 corresponding to the bonding portion 60 in the first direction as an example, the width of the solder strip is A mm, the length of the pad 50 is B mm, the width of the bonding portion 60 is C mm, and the distance between the bonding portion 60 and the pad 50 is d 1 mm, the distance between pad 50 and the edge of the solder strip is d 2 mm, then B=ACd 1 -d 2 .

[0089] Understandably, Figure 4 The change trend of the middle pad 50 may be an increasing trend, a decreasing trend, or a constant trend, etc., which is not specifically limited here.

[0090] In actual implementation, the width C of the bonding portion 60 is 15%Amm to 30%Amm, and the distance d between the bonding portion 60 and the pad 50 is 1 The distance d between the pad 50 and the edge of the solder strip is 100 μm to 300 μm. 2 It is 100 μm to 300 μm, and the length B of the pad 50 can be (0.7A-0.6) mm to (0.85A-0.2) mm.

[0091] For example: the width of the soldering tape is 2 mm, the width of the adhesive portion 60 is 0.6 mm, the distance between the adhesive portion 60 and the soldering pad 50 is 300 μm, and the distance between the soldering pad 50 and the edge of the soldering tape is 300 μm, then the length of the soldering pad 50 is 0.8 mm; or the width of the soldering tape is 2 mm, the width of the adhesive portion 60 is 0.3 mm, the distance between the adhesive portion 60 and the soldering pad 50 is 100 μm, and the distance between the soldering pad 50 and the edge of the soldering tape is 100 μm, then the length of the soldering pad 50 is 1.5 mm; or the width of the soldering tape is 2 mm, the width of the adhesive portion 60 is 0.4 mm, the distance between the adhesive portion 60 and the soldering pad 50 is 200 μm, and the distance between the soldering pad 50 and the edge of the soldering tape is 200 μm, then the length of the soldering pad 50 is 1.2 mm.

[0092] The back contact battery provided by the embodiment of the present invention can improve the bonding force by alternately arranging bonding parts on both sides of the series connection area. The length of the pad corresponding to the bonding part in the first direction can be adjusted according to the size of the bonding part to ensure effective bonding force and welding tension.

[0093] Figure 5 Schematic diagram of the structure of the photovoltaic module provided by the embodiment of the present invention. Figure 5 As shown, the present invention further provides a photovoltaic module 100, comprising the back contact cell 101 in any of the above embodiments.

[0094] The back contact cell 101 has been described in detail in the above embodiment and will not be described again here.

[0095] In this embodiment, multiple solar cells in the photovoltaic module 100 can be connected in series in sequence to form a battery string, thereby realizing the series bus output of current. For example, the series connection of battery cells can be realized by setting welding strips (bus bars, interconnection bars), conductive backplanes, etc.

[0096] It is understandable that in such an embodiment, the photovoltaic module 100 may also include a metal frame, a back plate, photovoltaic glass and an adhesive film. The adhesive film may be filled between the front and back of the solar cell and the photovoltaic glass, adjacent cells, etc. As a filler, it may be a transparent colloid with good light transmission and aging resistance. For example, the adhesive film may be an EVA adhesive film or a POE adhesive film. The specific selection may be based on actual conditions and is not limited here.

[0097] Photovoltaic glass can cover the adhesive film on the front of the solar cell. The photovoltaic glass can be ultra-white glass, which has high light transmittance, high transparency, and excellent physical, mechanical and optical properties. For example, the light transmittance of ultra-white glass can reach more than 92%, which can protect the solar cell without affecting the efficiency of the solar cell as much as possible. At the same time, the adhesive film can bond the photovoltaic glass and the solar cell together. The presence of the adhesive film can seal and insulate the solar cell and make it waterproof and moisture-proof.

[0098] The backplane can be attached to the adhesive film on the back of the solar cell. The backplane can protect and support the solar cell and has reliable insulation, water resistance and aging resistance. There are multiple options for the backplane, which can usually be tempered glass, organic glass, aluminum alloy TPT composite adhesive film, etc. It can be set according to the specific situation and is not limited here. The whole composed of the backplane, solar cell, adhesive film and photovoltaic glass can be set on a metal frame. The metal frame serves as the main external support structure of the entire photovoltaic module 100 and can stably support and install the photovoltaic module 100. For example, the photovoltaic module 100 can be installed at the required installation position through the metal frame.

[0099] The photovoltaic module provided by the embodiment of the present invention has welding pads of different lengths arranged in the series connection area of ​​the battery cell, and the length of the welding pads in the partial area between the edge of the battery cell and the center line shows a decreasing trend, which can increase the connection tension between the welding strip and the auxiliary grid near the edge area, improve the firmness of the welding of the welding strip, reduce the risk of poor connection of the welding strip due to uneven tension, and ensure that the photoelectric conversion efficiency of the back contact battery is not affected; on the other hand, the length of the welding pads in some areas decreases successively, which can reduce the slurry loss without affecting the welding effect, thereby reducing the component cost and improving the photoelectric conversion efficiency of the back contact battery.

[0100] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0101] It is understandable that those skilled in the art can, under the guidance of the above embodiments, combine various implementation methods in the above embodiments to obtain technical solutions of multiple implementation methods.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A back contact battery, characterized in that: include: A battery cell, a first auxiliary grid and a second auxiliary grid, wherein the first auxiliary grid and the second auxiliary grid have different polarities; The first auxiliary grid and the second auxiliary grid are arranged on the back side of the battery cell and extend along a first direction, the first auxiliary grid and the second auxiliary grid are alternately arranged along a second direction, and the first direction is perpendicular to the second direction; A plurality of series connection areas are provided on the back of the battery cell, and the series connection areas are used to collect the current collected by the first auxiliary grid or the second auxiliary grid through the welding pad; each series connection area extends along the second direction; The battery sheet has a first edge and a second edge opposite to each other in the second direction; The lengths of the pads in a partial area between the first edge and / or the second edge and the center line of the battery cell decrease in sequence.

2. The back contact cell according to claim 1, characterized in that: There are a first boundary line and a second boundary line between the first edge and the second edge and the midline respectively; The length of the pad between the center line and the first boundary line remains unchanged, the length of the pad between the first boundary line and the first edge increases successively, the length of the pad between the center line and the second boundary line remains unchanged, and the length of the pad between the second boundary line and the second edge increases successively.

3. The back contact cell according to claim 1 or 2, characterized in that: In the case where at least one adhesive portion is provided in the series connection area, the adhesive portion extends along the second direction, and the length of the pad corresponding to the adhesive portion in the first direction varies based on the width of the adhesive portion in the first direction.

4. The back contact cell according to claim 3, characterized in that: The bonding portion is used to bond with the soldering strip, and the width of the bonding portion in the first direction accounts for 15% to 30% of the width of the soldering strip.

5. The back contact battery according to claim 3, characterized in that: The plurality of bonding portions are alternately distributed along the second direction on both sides of the center line of the serial connection area.

6. The back contact cell according to claim 3, characterized in that: There is a gap between the pad corresponding to the bonding portion in the first direction and the bonding portion.

7. The back contact cell according to claim 3, characterized in that: The interval between the bonding pad corresponding to the bonding portion in the first direction and the bonding portion is 100 μm to 300 μm.

8. The back contact battery according to claim 2, characterized in that: The second boundary line and the first boundary line are symmetrical about the midline.

9. The back contact cell according to claim 1 or 2, characterized in that: The pads in each of the series connection areas are symmetrical about the center line.

10. The back contact cell according to claim 1 or 2, characterized in that: The series connection area is used for placing the welding strip.

11. A photovoltaic module, characterized in that: include: A back contact battery according to any one of claims 1 to 10.

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