Bus bar, battery string and photovoltaic module

Abstract

The utility model relates to a bus bar, a battery string and a photovoltaic module. When in use, one end of each branch is electrically connected with the main circuit, and the other end of each branch on the same side of the main circuit is correspondingly and electrically connected with each bus grid line of the same polarity of at least one battery piece, so that each bus grid line of the same polarity of the at least one battery piece collects current and then converges the current to the main circuit through the branch. Therefore, the welding strip can be reduced or even completely not needed, so that the problems of shading of the welding strip, welding of the welding strip and increase of the process difficulty caused by arrangement of insulation paste are solved, the light receiving area of the battery piece can be increased, the light efficiency is improved, warping of the battery piece in the string forming process can be obviously reduced, and the product yield and reliability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic, in particular to a busbar, a cell string and a photovoltaic module. BACKGROUND

[0002] With the development of solar cell technology, various types of solar cells such as BC (Back Contact), PERC (Passivated Emitter and Rear Cell), TOPCon (Topography Control), HJT (Hetero junction with Intrinsic Thin-film) and the like have appeared.

[0003] However, the solder strip and the busbar in the related art will cause a large amount of light shielding, resulting in low light efficiency. In addition, in the process of stringing, the welding method of the solder strip and the cell sheet and the welding method of the solder strip and the busbar will cause a large amount of warping of the cell sheet, affecting the yield and the reliability of the photovoltaic module. Invention content

[0004] Therefore, it is necessary to overcome the defects of the prior art and provide a busbar, a cell string and a photovoltaic module, which can reduce or even eliminate the use of solder strips, improve light efficiency, and improve product yield and reliability.

[0005] A busbar, comprising:

[0006] an insulating carrier; and

[0007] a busbar circuit, disposed on the insulating carrier, the busbar circuit comprising a main circuit and a plurality of branch circuits disposed on at least one side of the main circuit, the plurality of branch circuits being electrically connected to the main circuit, and the plurality of branch circuits being sequentially and spacedly disposed along the extension direction of the main circuit.

[0008] In one embodiment, the insulating carrier is wrapped outside the busbar circuit, one end of the branch circuit is connected to the main circuit, and the other end is exposed to one side of the insulating carrier.

[0009] In one embodiment, the insulating carrier is provided as a light-transmitting carrier.

[0010] In one embodiment, the insulating carrier is provided as a light-transmitting carrier.

[0011] A battery string comprises a plurality of battery pieces and a first busbar connected between any two adjacent battery pieces; each battery piece is provided with a plurality of busbar grid lines; the first busbar adopts the busbar, and each side of the main path is provided with a plurality of branch paths; each branch path on the opposite side of the main path is respectively electrically connected with each busbar grid line of the same polarity of the adjacent two battery pieces.

[0012] In one embodiment, the cross-sectional area of the main path along its extension direction is 0.001mm 2 to 0.5mm 2 ; and / or, the number of busbar grid lines on the battery piece is 100 to 2000.

[0013] In one embodiment, the first connecting point is provided on one end of the branch path away from the main path, and the first connecting point is used for welding connection with the second connecting point of the busbar grid line.

[0014] A photovoltaic module comprises at least one battery string.

[0015] A photovoltaic module comprises at least two battery strings and a second busbar, and the at least two battery strings are connected in parallel through the second busbar; each battery string comprises at least two battery pieces connected in series, and each battery piece close to the second busbar is provided with a plurality of busbar grid lines; the second busbar adopts the busbar, and each branch path of the second busbar is electrically connected with each busbar grid line of the same polarity close to the second busbar.

[0016] In one embodiment, the battery string adopts the battery string; and / or,

[0017] The cross-sectional area of the main path of the second busbar along its longitudinal direction is 0.5mm 2 to 5mm 2 .

[0018] In the aforementioned busbars, battery strings, and photovoltaic modules, one end of each branch is electrically connected to the main circuit, and the other end of each branch on the same side of the main circuit is electrically connected to the corresponding busbars of at least one battery cell of the same polarity. Thus, the busbars of the same polarity of at least one battery cell collect current and then converge it to the main circuit through the branch. Therefore, this embodiment eliminates the need for the structure of connecting the main grid and busbar of the battery cell separately using solder ribbons, as in related technologies. Instead, the current is directly collected by the busbars on the battery cell, and the current on the busbars is directly transmitted to the bus line and output through the bus line. This reduces or even completely eliminates the need for solder ribbons, thereby avoiding the problems of solder ribbon shading and soldering. This increases the light-receiving area of ​​the battery cell, improving light efficiency, and significantly reduces warpage during battery cell stringing, thus improving product yield and reliability. Attached Figure Description

[0019] Figure 1 This is a structural diagram of a busbar according to an embodiment of this application.

[0020] Figure 2 for Figure 1 The cross-sectional view of the busbar shown at point AA.

[0021] Figure 3 for Figure 2 The diagram shows a cross-sectional view of the busbar at BB in one embodiment.

[0022] Figure 4 for Figure 2 The shown is a cross-sectional view of another embodiment of the busbar at BB.

[0023] Figure 5 for Figure 1 The diagram shows the structure of several different shapes of the first connection point of the busbar.

[0024] Figure 6 This is a structural diagram of a battery string according to an embodiment of this application.

[0025] Figure 7 for Figure 6 The diagram shows the exploded structure of the battery string.

[0026] Figure 8 This is a structural diagram of a photovoltaic module according to an embodiment of this application.

[0027] 10. Busbar; 101. First busbar; 102. Second busbar; 11. Insulating carrier; 111. Reflective layer; 12. Busbar line; 121. Main line; 122. Branch line; 1221. First connection point; 20. Battery cell; 21. Busbar grid line; 211. Second connection point; 30. Battery string. Detailed Implementation

[0028] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0029] See Figures 1 to 3 , Figure 1 A structural diagram of a busbar 10 according to an embodiment of this application is shown. Figure 2 It shows Figure 1 The cross-sectional view of the busbar 10 shown at AA. Figure 3 It shows Figure 2 The diagram shows a cross-sectional view of the busbar 10 at point BB in one embodiment. One embodiment of this application provides a busbar 10, which includes an insulating carrier 11 and bus lines 12. The bus lines 12 are disposed on the insulating carrier 11. (The diagram is incomplete and requires further context.) Figure 2 and Figure 3 As shown, the busbar 12 includes a main line 121 and a plurality of branch lines 122 disposed on at least one side of the main line 121. The plurality of branch lines 122 are electrically connected to the main line 121, and the plurality of branch lines 122 are arranged sequentially at intervals along the extension direction of the main line 121.

[0030] Specifically, please refer to Figure 6 and Figure 7 Each branch 122 has one end electrically connected to the main line 121, and the other end of each branch 122 located on the same side of the main line 121 is used to be electrically connected to the corresponding busbar 21 of the same polarity of at least one battery cell 20. Alternatively, the other end of each branch 122 located on opposite sides of the main line 121 is used to be electrically connected to the corresponding busbar 21 of the same polarity of at least one battery cell 20.

[0031] In use, the aforementioned busbar 10, since the branch 122 is electrically connected to the main line 121, each branch 122 located on the same side of the main line 121 is also electrically connected, for example, to each busbar 21 of the same polarity of at least one solar cell 20. Thus, each busbar 21 of the same polarity of at least one solar cell 20 collects current and then flows it through the branch 122 to the main line 121. Therefore, in this embodiment, there is no need to adopt the structure of connecting the main grid and busbar of the solar cell separately with solder ribbon, as in related technologies. Instead, the current is directly collected by the busbar 21 on the solar cell 20, and the current on the busbar 21 is directly transmitted to the bus line 12 and output through the bus line 12. It can be seen that the use of solder ribbon can be reduced or even completely eliminated, thereby avoiding problems such as solder ribbon shading, solder ribbon welding, and increased process difficulty due to the use of insulating adhesive. This increases the light-receiving area of ​​the solar cell 20, improving light efficiency, and significantly reduces warpage during the stringing process of the solar cells 20, improving product yield and reliability.

[0032] Furthermore, for back-contact batteries, the welding ribbon between the positive and negative electrodes requires insulation to prevent short circuits in the battery string. This increases the manufacturing complexity and cost of photovoltaic modules. In this embodiment, the welding ribbon can be omitted, thereby increasing the bifaciality of the photovoltaic module, eliminating the need for insulating adhesive, and eliminating the risk of short circuits, thus reducing manufacturing complexity.

[0033] It should be noted that the busbar 10 in the above embodiment can be used not only for the series connection of two adjacent battery cells 20, thereby realizing the series connection of multiple battery cells 20 to form a battery string 30, such as... Figure 6 and Figure 7 As shown; it can also be used for parallel connection of at least two battery strings 30, such as Figure 8 As shown. Specific settings can be flexibly configured according to actual needs; no limitations are specified here.

[0034] Please see Figure 6 and Figure 7In an embodiment of the present application, a battery string 30 includes at least two battery pieces 20 connected in series and a first busbar 101 connected between any two adjacent battery pieces 20, wherein the first busbar 101 is connected by the busbar 10 in any of the above embodiments. Therefore, in the busbar 10 in any of the above embodiments, a plurality of branch paths 122 are arranged on each side of the main path 121 to match the connection of the busbar grid lines 21 of the same polarity of the two adjacent battery pieces 20. Specifically, each branch path 122 on the opposite side of the main path 121 is electrically connected to the busbar grid line 21 of the same polarity of the two adjacent battery pieces 20, so that the busbar grid lines 21 of the same polarity of the two adjacent battery pieces 20 collect and transmit the collected current to each branch path 122, and then the current is transmitted to the main path 121 by each branch path 122 and then outputted to the outside through the main path 121.

[0035] The battery string 30 described above has the technical effects brought by the busbar 10, and the beneficial effects include the beneficial effects of the busbar 10, which will not be repeated here.

[0036] In some embodiments, the photovoltaic module provided in an embodiment of the present application includes at least one battery string 30 in any of the above embodiments.

[0037] The photovoltaic module described above has the technical effects brought by the battery string 30, and the beneficial effects include the beneficial effects of the busbar 10, which will not be repeated here.

[0038] Optionally, after the battery pieces 20 are connected in series, the connection between at least two battery strings 30 can be achieved by the busbar 10 in any of the above embodiments or by the busbar 10 in the related art.

[0039] Please refer to Figure 8Another embodiment of this application provides a photovoltaic module including at least two cell strings 30 and a second busbar 102. The at least two cell strings 30 are connected in parallel via the second busbar 102. The cell strings 30 can be any of the aforementioned embodiments or related technologies, and are not limited here. Each cell string 30 includes at least two cells 20 connected in series, and the cells 20 near the second busbar 102 on the cell string 30 are provided with multiple busbar lines 21. The at least two cell strings 30 are combined together in parallel via the second busbar 102, which is a busbar 10 of any of the aforementioned embodiments. Each branch 122 of the second busbar 102 is electrically connected to a corresponding busbar line 21 of the same polarity near the second busbar 102. Specifically, when the second busbar 102 is positioned beside the photovoltaic module, i.e., all cell strings 30 are located on the same side of the second busbar 102, multiple branch lines 122 are provided on one side of the main path 121 of the second busbar 102 to match and connect the multiple busbar lines 21 of the same polarity on the cell 20 closest to the busbar 10 of each cell string 30. No branch lines 122 are needed on the other side of the main path 121. When the second busbar 102 is positioned in the middle of the photovoltaic module, i.e., the two sides of the second busbar 102 are... When there are at least two battery strings 30, each side of the main path 121 of the second busbar 102 is provided with multiple branches 122. The multiple branches 122 on one side of the main path 121 are used to match and connect one-to-one multiple busbar grid lines 21 of the same polarity on the battery cell 20 of each battery string 30 on one side of the second busbar 102 that is closest to the busbar 10. The multiple branches 122 on the other side are used to match and connect one-to-one multiple busbar grid lines 21 of the same polarity on the battery cell 20 of each battery string 30 on the other side of the second busbar 102 that is closest to the busbar 10.

[0040] The photovoltaic module described above, since the second busbar 102 adopts the busbar 10 of any of the above embodiments, its technical effect is brought about by the busbar 10. Therefore, the beneficial effects include the beneficial effects of the busbar 10, which will not be repeated here.

[0041] The first busbar 101 used between any two adjacent battery cells 20 in the battery string 30 is, for example, as shown in the example... Figure 3 As shown, for the first busbar 101, the cross-sectional area of ​​the main path 121 along its longitudinal direction can be flexibly adjusted and set according to the actual current merging requirements, and is not limited here. Optionally, the cross-sectional area of ​​the main path 121 along its extension direction of the first busbar 101 may include, but is not limited to, 0.001 mm². 2 up to 0.5mm 2Thus, the cross-sectional area of the main path 121 of the first bus bar 101 is not too large to cause shading to the light and reduce the utilization of the light, and is not too small to meet the bus bar requirement.

[0042] In addition, please refer to Figure 3 and Figure 4 The cross-sectional shape of the main path 121 of the second bus bar 102 along the longitudinal direction is as shown in Figure 4 Compared with the first bus bar 101 used between any two adjacent battery pieces 20 in the battery string 30, the cross-sectional area of the main path 121 of the second bus bar 102 is larger, which can meet the larger current carrying requirement. Optionally, the cross-sectional area of the main path 121 of the second bus bar 102 along the longitudinal direction is 0.5mm 2 to 5mm 2 .

[0043] Please refer to Figure 1 and Figure 2 In an embodiment, the insulating carrier 11 is wrapped outside the bus bar circuit 12, one end of the branch path 122 is connected to the main path 121, and the other end is exposed to one side of the insulating carrier 11. Thus, the insulating carrier 11 plays a protective role for the bus bar circuit 12, and can make the bus bar circuit 12 externally insulated; in addition, the end of the branch path 122 away from the main path 121 is exposed to the side of the insulating carrier 11 facing the battery piece 20, so as to facilitate electrical connection with the bus bar grid line 21 on the battery piece 20.

[0044] In some embodiments, the bus bar 10 is formed by, for example, multi-layer material compounding. Specifically, the insulating carrier 11 includes but is not limited to two layers of insulating structures arranged in a stacked manner, and the bus bar circuit 12 is arranged between the two layers of insulating structures, for example.

[0045] In an embodiment, the insulating carrier 11 includes but is not limited to a light-transmitting carrier. Thus, the light reflection capability can be increased, thereby improving the utilization of the light. The light transmission rate of the light-transmitting carrier includes but is not limited to 50% or more, specifically, for example, 50%, 60%, 70% or 90% and the like.

[0046] Of course, as some optional solutions, the insulating carrier 11 can also be a non-light-transmitting carrier, that is, the light transmission rate is less than 50%, for example, 30%, 20%, 10% or 1% and the like.

[0047] Optionally, the insulating carrier 11 can be a colorless light-transmitting carrier, or a colored light-transmitting carrier, or a colored non-light-transmitting carrier and the like. The color includes but is not limited to black, white, red, orange, yellow, green, blue, indigo, purple, pink or brown and various colors.

[0048] In some embodiments, the insulating carrier 11 includes but is not limited to various insulating materials such as PET, EVA, POE, PP or resin, etc., which can be selected according to actual needs.

[0049] In some embodiments, the bus line 12 includes but is not limited to metal materials such as copper, aluminum, zinc, silver, tin, etc., and can also be graphene materials or other conductive materials.

[0050] It should be noted that the connection mode of the end of the branch line 122 away from the main line 121 to the bus grid line 21 includes but is not limited to welding or using conductive glue for bonding, etc. In this embodiment, the end of the branch line 122 away from the main line 121 to the bus grid line 21 is specifically taken as an example to develop.

[0051] Please refer to Figure 3 , Figure 6 and Figure 7 In one embodiment, the end of the branch line 122 away from the main line 121 is provided with a first connecting point 1221. One end of the bus grid line 21 is provided with a second connecting point 211. The first connecting point 1221 is used for welding connection with the second connecting point 211 of the bus grid line 21.

[0052] Please refer to Figure 4 , Figure 6 and Figure 7 In some embodiments, the first connecting point 1221 includes but is not limited to various shapes such as circle, triangle, rectangle, pentagon, hexagon or trapezoid, etc., as shown in Figure 4 The specific shape of the first connecting point 1221 can be flexibly adjusted and set according to actual needs, which is not limited here. In addition, the second connecting point 211 is specifically the same as the shape of the first connecting point 1221, so as to facilitate stable welding connection with the first connecting point 1221 and have better conductivity.

[0053] It should be noted that in this embodiment, for any two adjacent battery pieces 20 in the battery string 30, the two battery pieces 20 can be spaced apart, in which case the spacing between the two battery pieces 20 is controlled to be within 5mm, for example; can be strictly butted together, in which case the spacing between the two battery pieces 20 is 0; or can be stacked together, in which case the width of the stacked part of the two battery pieces 20 is controlled to be within 5mm, for example.

[0054] Please refer to Figure 2 In one embodiment, the side of the insulating carrier 11 facing the battery piece 20 is provided with a reflective layer 111. In this way, when the two adjacent battery pieces 20 have a spacing, the reflective layer 111 is exposed in the spacing area between the two battery pieces 20, so as to improve the light reflection rate and thereby improve the light utilization rate.

[0055] Specifically, the light-reflecting layer 111 can be a light-reflecting film adhered to the insulating carrier 11, a high-reflectivity material coated or printed on the insulating carrier 11, or the like.

[0056] In some embodiments, the cross section of the bus bar 10 along the longitudinal direction includes, but is not limited to, a rectangle, a circle, an ellipse, a pentagon, a hexagon, a triangle, or the like. For example, the cross section of the bus bar 10 along the longitudinal direction is a rectangle. Figure 1 In some embodiments, the cross section of the bus bar 10 along the longitudinal direction is a rectangle. Figure 2 In some embodiments, the cross section of the bus bar 10 along the longitudinal direction is a rectangle. Specifically, the length of the bus bar 10 is L, the width is W, and the thickness is d. For example, L is 100 mm-300 mm, W is 2 mm-20 mm, and d is 0.1 mm-5 mm.

[0057] For example, when the cell 20 is a back contact cell, the bus grid lines 21 on the cell 20 are divided into two polarities, i.e., positive bus grid lines and negative bus grid lines, which are arranged alternately on the back surface of the back contact cell 20. In addition, when the cell 20 is a TOPCon cell or a HJT cell, the front surface of the cell 20 is provided with a plurality of bus grid lines 21 of one polarity, e.g., positive bus grid lines, and the back surface of the cell 20 is provided with a plurality of bus grid lines 21 of the other polarity, e.g., negative bus grid lines.

[0058] In some embodiments, the bus grid lines 21 are parallel to the width direction y of the cell 20, i.e., the bus grid lines 21 are arranged in sequence along the length direction x of the cell 20. In addition, the head or tail of the bus grid line 21 is provided with a second connecting point 211 for electrical connection with the first connecting point 1221, which serves as the connection between the cells 20 and the bus bar 10.

[0059] In some embodiments, the series connection method of the cell string 30 includes the following steps:

[0060] In step S100, tin paste is printed on the second connecting point 211, and then the cells 20 are placed in a string according to the required number.

[0061] In step S200, a bus bar 10 is placed between any two adjacent cells 20, so that each first connecting point 1221 is in abutment with each second connecting point 211, and then welding is performed.

[0062] Optionally, the welding method can be infrared heating welding, laser welding, needle pressing and heat conduction welding, or the like, and the welding can also be performed by lamination to achieve metallization connection.

[0063] Therefore, during the string welding process, the battery piece 20 does not need to be heated in a large area, and only the head and tail welding points are locally heated.

[0064] The main grid lines on one battery piece 20 in the related art are usually 6 to 30, and in the embodiment, the number of the bus grid lines 21 on one battery piece 20 includes but is not limited to 100 to 2000, which can be flexibly adjusted and set according to actual needs. In this way, when the bus grid lines 21 increase, not only the welding strip and the auxiliary grid lines can be removed, but also the bus path can be shortened, thereby improving the bus efficiency; in addition, the number of the bus grid lines 21 is large, and the carrier collection effect will be better.

[0065] In the description of the present application, it should be understood that if these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like appear, these terms indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0066] In addition, if these terms "first", "second" appear, these terms are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, if the term "multiple" appears, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0067] In the present application, unless otherwise explicitly specified and limited, if the terms "mounting", "connecting", "connecting", "fixing" and the like appear, these terms should be understood in a broad sense. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0068] In the present application, unless specifically defined otherwise, if there is an expression "on" or "under" or similar, it can mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "on", "above" and "over" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "under", "below" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0069] It should be noted that if an element is referred to as being "fixed" or "attached" to another element, it can be directly on the other element or there can be an intervening element. If an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements can be present. If present, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions as used herein are for purposes of explanation only and are not intended to be limiting.

[0070] The technical features of the above-described embodiments can be combined in any manner, and in order to make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered to be within the scope of the present disclosure.

[0071] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the application. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A busbar (10) characterized in that, The busbar (10) comprises: an insulating carrier (11); and a busbar circuit (12) disposed on the insulating carrier (11), the busbar circuit (12) comprising a main path (121) and a plurality of branch paths (122) disposed on at least one side of the main path (121), the plurality of branch paths (122) being electrically connected to the main path (121), and the plurality of branch paths (122) being sequentially and spacedly disposed along the extension direction of the main path (121).

2. The busbar (10) according to claim 1, characterized in that The insulating carrier (11) is wrapped outside the busbar circuit (12), one end of the branch path (122) is connected to the main path (121), and the other end is exposed to one side of the insulating carrier (11).

3. The busbar (10) according to claim 1, characterized in that The insulating carrier (11) is provided as a light-transmitting carrier.

4. The busbar (10) according to claim 1, characterized in that The insulating carrier (11) is provided with a reflective layer (111) on the side facing the battery piece (20).

5. A battery string (30) characterized by The battery string (30) comprises a plurality of battery pieces (20) and a first busbar (101) connected between any two adjacent battery pieces (20); the battery piece (20) is provided with a plurality of busbar grid lines (21); the first busbar (101) adopts the busbar (10) of any one of claims 1 to 4, and a plurality of branch paths (122) are provided on each side of the main path (121); each branch path (122) on the opposite sides of the main path (121) is respectively electrically connected to each busbar grid line (21) of the same polarity of the adjacent two battery pieces (20).

6. The battery string (30) according to claim 5, characterized in that The main road (121) has a cross-sectional area of 0.001 mm 2 to 0.5 mm 2 ; and / or the number of bus bars (21) on the battery piece (20) is 100 to 2000.

7. The battery string (30) according to claim 5, characterized in that The first connecting point (1221) is provided on the end of the branch path (122) away from the main path (121), and the busbar grid line (21) is provided with a second connecting point (211), and the first connecting point (1221) and the second connecting point (211) are welded.

8. A photovoltaic module, characterized by, The photovoltaic module comprises at least one battery string (30) according to any one of claims 5 to 7.

9. A photovoltaic module, characterized by The photovoltaic module comprises at least two battery strings (30) and a second busbar (102), and the at least two battery strings (30) are connected in parallel through the second busbar (102); the battery string (30) comprises at least two battery pieces (20) connected in series, and the battery piece (20) close to the second busbar (102) on the battery string (30) is provided with a plurality of busbar grid lines (21); the second busbar (102) adopts the busbar (10) of any one of claims 1 to 4, and each branch path (122) of the second busbar (102) is electrically connected to each busbar grid line (21) of the same polarity close to the second busbar (102).

10. The photovoltaic module of claim 9, wherein, The battery string (30) adopts the battery string (30) of any one of claims 5 to 7; and / or, The main path (121) of the second bus bar (102) has a cross-sectional area of 0.5 mm 2 to 5 mm 2 .

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