Back contact battery assembly and photovoltaic system

Abstract

The invention is suitable for the technical field of solar cells, and provides a back contact cell module and a photovoltaic system. The back contact battery assembly comprises a battery string which comprises a plurality of battery pieces, each battery piece is provided with a first face and a second face which are opposite, the second face is provided with a plurality of grid lines, the grid lines extend in the first direction and are sequentially arranged in the second direction, and the first direction and the second direction intersect; the plurality of welding strips are connected with two adjacent battery pieces, and the plurality of welding strips are sequentially arranged along the second direction and cover the grid lines; in the second direction, the welding strip is provided with a first long side and a second long side which are opposite; wherein in the first direction, the distance from at least part of the first long edge of the welding strip to the grid line covered by the welding strip is gradually increased. Therefore, the distance from at least part of the first long edge of the solder strip to the grid line covered by the solder strip is gradually increased, so that the battery assembly has different current densities and heat distribution, and the effect of improving the performance and the efficiency of the battery assembly is achieved.

Description

Technical Field

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

[0002] At present, back-contact cells refer to solar cells with no electrodes on the light-facing side of the cell, and both the positive and negative electrodes are arranged on the backlight side of the cell. This can reduce the shading of the electrodes on the cell, increase the short-circuit current of the cell, and improve the energy conversion efficiency of the cell.

[0003] However, in the prior art, the distance from one side of the welding strip to the grid line covered by the welding strip is usually the same, so the current density and heat distribution between the welding strip and the grid line are also the same. However, in a battery assembly, different positions of the battery assembly may face different current density and heat distribution requirements. Therefore, the flexibility of the welding strip and grid line arrangement method of the prior art is insufficient, and it is impossible to fully meet the current density and heat distribution requirements of different positions of the battery assembly. Summary of the invention

[0004] The present invention provides a back-contact cell assembly and a photovoltaic system, aiming to solve the problem of insufficient flexibility in the arrangement of welding strips and grid lines of the back-contact cell assembly.

[0005] A back-contact battery assembly provided by the present invention comprises: a battery string, comprising a plurality of battery cells, wherein the battery cells have a first surface and a second surface opposite to each other, a plurality of grid lines are arranged on the second surface, the plurality of grid lines extend along a first direction and are arranged in sequence along a second direction, and the first direction and the second direction intersect; a plurality of welding strips, wherein the welding strips connect two adjacent battery cells, the plurality of welding strips are arranged in sequence along the second direction and cover the grid lines; the welding strips have a first long side and a second long side opposite to each other; wherein, along the first direction, the distance from at least a portion of the first long side of the welding strip to the grid lines covered by the welding strips gradually increases.

[0006] Furthermore, along the second direction, the first sides of the plurality of grid lines are connected to form a third long side, the second sides of the plurality of grid lines are connected to form a fourth long side, and the third long side and the fourth long side are completely covered by the welding strip.

[0007] Furthermore, along the second direction, the first sides of the plurality of gate lines are connected to form a third long side, the second sides of the plurality of gate lines are connected to form a fourth long side, the third long side is completely covered by the welding strip, and part of the fourth long side is covered by the welding strip.

[0008] Furthermore, along the second direction, the first sides of the plurality of gate lines are connected to form a third long side, the second sides of the plurality of gate lines are connected to form a fourth long side, the fourth long side is completely covered by the welding strip, and part of the third long side is covered by the welding strip.

[0009] Furthermore, along the second direction, the first sides of the plurality of gate lines are connected to form a third long side, the second sides of the plurality of gate lines are connected to form a fourth long side, part of the third long side is covered by the welding strip, and part of the fourth long side is covered by the welding strip.

[0010] Furthermore, along the first direction, the distance from at least a portion of the second long side of the soldering strip to the gate line covered by the soldering strip gradually decreases.

[0011] Furthermore, the welding strip extends along a third direction, and an angle between the first direction and the third direction is an acute angle.

[0012] Furthermore, along the first direction, the distance L between at least part of the first long side of the soldering strip and the gate line covered by the soldering strip is 1 The distance L between at least part of the second long side of the solder strip and the gate line covered by the solder strip is 2 Satisfies the following relationship: L 1 +L 2 =d / cosα; wherein d is the width of the welding strip, and α is the angle between the first direction and the third direction.

[0013] Furthermore, along the first direction, L 1 The absolute value of the increase in L 2 The absolute value of the reduction is the same.

[0014] Furthermore, the second surface is provided with a first doping layer and a second doping layer, the first doping layer and the second doping layer extend along the first direction and are alternately distributed along the second direction; the welding strip electrically connects the first doping layer of the battery cell and the second doping layer of the adjacent battery cell respectively.

[0015] Furthermore, the angle α between the first direction and the third direction satisfies the following relationship: 0<tanα≤D / T; wherein T is the total length of the farthest ends of the first battery cell and the last battery cell in the battery string along the first direction, and D is the width of any doping layer of the battery cell along the second direction.

[0016] Furthermore, the center distance between two adjacent gate lines is equal; the center distance between two adjacent gate lines is equal to the center distance between two adjacent welding strips.

[0017] Furthermore, the welding strip is in a long strip shape, and the width of the welding strip is smaller than the interval between two adjacent gate lines.

[0018] The photovoltaic system provided by the embodiment of the present invention includes the back contact cell assembly described in any one of the above embodiments.

[0019] In the back contact battery assembly and photovoltaic system of the embodiment of the present invention, the back contact battery assembly includes: a battery string, including a plurality of battery cells, the battery cells have a first surface and a second surface relative to each other, a plurality of grid lines are arranged on the second surface, the plurality of grid lines extend along a first direction, and are arranged in sequence along a second direction, and the first direction and the second direction intersect; a plurality of welding strips, the welding strips connect two adjacent battery cells, the plurality of welding strips are arranged in sequence along the second direction, and cover the grid line arrangement; along the second direction, the welding strips have a first long side and a second long side relative to each other; wherein, along the first direction, the distance from at least part of the first long side of the welding strip to the grid line covered by the welding strip gradually increases. Therefore, by setting the distance from at least part of the first long side of the welding strip to the grid line covered by the welding strip to gradually increase, different current density and heat distribution can be achieved in the back contact battery assembly, thereby achieving the effect of improving the performance and efficiency of the back contact battery assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the module structure of a photovoltaic system provided by an embodiment of the present invention;

[0021] Figure 2 is a schematic diagram of the module structure of a back contact battery assembly provided by an embodiment of the present invention;

[0022] Figure 3 is a partial structural schematic diagram of a back contact battery assembly provided by an embodiment of the present invention;

[0023] Figure 4 is another partial planar structural schematic diagram of a back contact battery assembly provided by an embodiment of the present invention;

[0024] Figure 5 yes Figure 3 A partial enlarged schematic diagram of a solder strip arrangement in a back contact battery assembly shown in FIG.

[0025] Figure 6 yes Figure 3 A partial enlarged schematic diagram of another solder strip arrangement in a back contact battery assembly shown in ;

[0026] Figure 7 yes Figure 3 A partial enlarged schematic diagram of another solder strip arrangement in a back contact battery assembly shown in ;

[0027] Figure 8 yes Figure 3 A partial enlarged schematic diagram of another solder strip arrangement in a back contact battery assembly shown in FIG.

[0028] Fig. 9 yes Figure 3 A partially enlarged schematic diagram of the arrangement of a welding strip in a back-contact battery assembly is shown in FIG.

[0029] Explanation of main component symbols: 1000, photovoltaic system; 100, back contact battery assembly; 200, battery string; 10, battery cell; 11, grid line; 12, second side; 20, welding ribbon; 21, first long side; 22, second long side; 111, third long side; 112, fourth long side; 121, first doped layer; 122, second doped layer. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, 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.

[0031] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations 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 a limitation on the present invention.

[0032] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, 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 "plurality" is two or more, unless otherwise clearly and specifically defined.

[0033] 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.

[0034] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0035] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use scenarios of other materials.

[0036] See also Figure 1, the photovoltaic system 1000 in the embodiment of the present invention may include the back contact battery assembly 100 in the embodiment of the present invention. The photovoltaic system 1000 can be applied in photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic system 1000 are not limited to this, that is, the photovoltaic system 1000 can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system 1000 may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple back contact battery assemblies 100. For example, multiple back contact battery groups may form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid, and then connected to the mains network to realize solar power supply.

[0037] See also Figure 2 , Figure 3 , Figure 4 and Figure 5 A back-contact battery assembly 100 provided by the present invention includes a battery string 200 and a welding strip 20. The battery string 200 includes a plurality of battery cells 10 and a plurality of welding strips 20. The battery cell 10 has a first surface and a second surface 12 relative to each other. Optionally, the first surface of the battery cell 10 is the light-facing surface of the battery cell 10, and the second surface 12 of the battery cell 10 is the backlight surface of the battery cell 10. An electrode is arranged on the second surface 12 of the battery cell 10. A plurality of grid lines 11 are arranged on the second surface 12 of the battery cell 10. The grid lines 11 can specifically be fine grid lines 11 or main grid lines 11. The plurality of grid lines 11 extend along a first direction and are arranged in sequence along a second direction. The first direction and the second direction intersect. In an embodiment of the present invention, the first direction is described as a horizontal direction and the second direction is described as a vertical direction. In other embodiments, the first direction and the second direction can also be diagonal directions, which are not limited here.

[0038] The welding strip 20 of the back contact battery assembly 100 connects two adjacent battery cells 10, and a plurality of welding strips 20 are arranged in sequence along the second direction and cover the grid line 11, and each welding strip 20 has a first long side 21 and a second long side 22 relative to each other. Among them, along the first direction, the distance from at least part of the first long side 21 of the welding strip 20 to the grid line 11 covered by the welding strip 20 gradually increases. In an embodiment of the present invention, each welding strip 20 is correspondingly covered on a grid line 11, and the polarity of each grid line 11 and the welding strip 20 covering the grid line 11 is the same. Optionally, the welding strip 20 can be a positive electrode welding strip 20 or a negative electrode welding strip 20. That is to say, a plurality of battery cells 10 can be connected in series by the welding strip 20 to form a battery string 200 distributed along the first direction, and after the welding strip 20 connects a plurality of battery cells 10 in series, it can also be selectively cut by laser to form a battery string 200 in pairs.

[0039] It is understandable that in the battery string 200, the battery string 200 may include two battery cells 10 connected in series, three battery cells 10 connected in series, or other larger numbers of battery cells 10, and the number of battery cells 10 to be connected in series may be determined according to actual usage. In addition, in the embodiment of the present invention, the size and type of the battery cells 10 are not limited, and the specifications and sizes of adjacent battery cells 10 may be the same or different to meet different needs.

[0040] In the embodiment of the present invention, the specific arrangement of adjacent battery cells 10 is not limited to meet different needs. In one embodiment, two adjacent battery cells 10 can be stacked together at least partially at their edges; in another embodiment, two adjacent battery cells 10 can also be arranged at intervals. The spacing between two adjacent battery cells 10 is within a suitable range, which can avoid the small operating space and high welding difficulty caused by too small spacing, and can also avoid the waste of component space and increased costs caused by too large spacing.

[0041] In the prior art, the distance from one side of the welding strip 20 to the grid line 11 covered by the welding strip 20 is usually the same, so the current density and heat distribution between the welding strip 20 and the grid line 11 are also the same. However, in the battery assembly, different positions of the battery assembly may face different current density and heat distribution requirements. However, in the embodiment of the present invention, for the arrangement of each welding strip 20, the distance from at least part of the first long side 21 of the welding strip 20 to the grid line 11 covered by the welding strip 20 is gradually increased. Therefore, by arranging the distance from at least part of the first long side 21 of the welding strip 20 to the grid line 11 covered by the welding strip 20 is gradually increased, it is possible to have different current densities and heat distributions in the back contact battery assembly 100, so as to achieve the effect of improving the performance and efficiency of the back contact battery assembly 100. It can be understood that, as a case, the distance from one side of the welding strip 20 to the grid line 11 covered by the welding strip 20 refers to the distance from one side of the welding strip 20 to the central axis of the grid line 11 along the first direction.

[0042] Furthermore, in the back-contact battery assembly 100, some areas may need to handle higher current density. If the distance between the welding ribbon 20 and the grid line 11 is the same, these areas may be overheated, reducing the efficiency and life of the battery in the back-contact battery assembly 100. Therefore, in an embodiment of the present invention, by setting the distance from at least part of the first long side 21 of the welding ribbon 20 to the grid line 11 covered by the welding ribbon 20 to be gradually increased, the current density at different positions in the back-contact battery assembly 100 can be optimized, so as to improve the performance of the back-contact battery assembly 100 and improve the adaptability and stability of the back-contact battery assembly 100 under different working conditions.

[0043] Further, for the second long side 22 of the soldering strip 20 opposite to the first long side 21, in a possible embodiment, the distance from at least part of the second long side 22 of the soldering strip 20 to the grid line 11 covered by the soldering strip 20 gradually decreases. Specifically, the second long side 22 is arranged relative to the first long side 21, and the soldering strip 20 is usually rectangular or quasi-rectangular in shape. Therefore, when the distance from at least part of the first long side 21 of the soldering strip 20 to the grid line 11 covered by the soldering strip 20 gradually increases, then for the second long side 22 of each soldering strip 20, the distance from at least part of the second long side 22 of the existing soldering strip 20 to the grid line 11 covered by the soldering strip 20 gradually decreases.

[0044] Similarly, in an embodiment of the present invention, by setting the distance from at least a portion of the second long side 22 of the welding strip 20 to the grid line 11 covered by the welding strip 20 to be gradually reduced, different current densities and heat distributions can be achieved in the back-contact battery assembly 100, and the current density at different positions in the back-contact battery assembly 100 can be optimized, thereby improving the performance and efficiency of the back-contact battery assembly 100, and improving the adaptability and stability of the back-contact battery assembly 100 under different working conditions.

[0045] Specifically, for the way in which the welding strip 20 covers the gate line 11, as shown in FIG. Figure 6 , Figure 7 , Figure 8 and Fig. 9 As shown, optionally, the first sides of the plurality of gate lines 11 are connected to form a third long side 111, and the second sides of the plurality of gate lines 11 are connected to form a fourth long side 112. Specifically, the first side and the second side of the gate line 11 are two opposite sides of the gate line 11, and the third long side 111 and the fourth long side 112 are formed by the plurality of gate lines 11 in the same first direction. That is, the relative position of each of the plurality of gate lines 11 forming the third long side 111 and the fourth long side 112 on the corresponding battery cell 10 is the same. The first gate line 11 of the plurality of gate lines 11 may be the gate line 11 on the first battery cell 10 in a certain battery string 200, and the last gate line 11 of the plurality of gate lines 11 may be the gate line 11 on the last battery cell 11 in a certain battery string 200.

[0046] like Figure 6 As shown, the third long side 111 and the fourth long side 112 may be completely covered by the welding strip 20; or Figure 7 As shown, the third long side 111 is completely covered by the welding strip 20, and part of the fourth long side 112 is covered by the welding strip 20; or Figure 8 As shown, the fourth long side 112 is completely covered by the welding strip 20, and part of the third long side 111 is covered by the welding strip 20; or, as Fig. 9 As shown, a portion of the third long side 111 is covered by the soldering strip 20 , and a portion of the fourth long side 112 is covered by the soldering strip 20 .

[0047] Specifically, the distance from at least a portion of the first long side 21 of the soldering strip 20 to the gate line 11 covered by the soldering strip 20 is gradually increased. Figure 6 As shown, when the gate line 11 is covered by the welding strip 20 , the third long side 111 and the fourth long side 112 of the gate line 11 may be completely covered by the welding strip 20 , that is, the gate line 11 is completely covered by the welding strip 20 .

[0048] Furthermore, if Figure 7As shown, when the gate line 11 is covered by the welding strip 20, the third long side 111 of the gate line 11 may be completely covered by the welding strip 20, and part of the fourth long side 112 of the gate line 11 may be covered by the welding strip 20. That is, part of the gate line 11 protrudes from the welding strip 20, the third long side 111 of the gate line 11 is completely covered by the welding strip 20, the fourth long side 112 of the gate line 11 is partially covered by the welding strip 20, and part of the fourth long side 112 of the gate line 11 protrudes from the welding strip 20. In addition, the distance from the first long side 21 to the fourth long side 112 of the welding strip 20 first decreases and then increases. Of course, in other embodiments, the distance from the first long side 21 to the fourth long side 112 of the welding strip 20 may also be set to first increase and then decrease. Further, as Figure 8 As shown, when the gate line 11 is covered by the welding strip 20, the fourth long side 112 of the gate line 11 may be completely covered by the welding strip 20, and part of the third long side 111 of the gate line 11 may be covered by the welding strip 20. That is, the gate line 11 is partially protruding from the welding strip 20, the fourth long side 112 of the gate line 11 is completely covered by the welding strip 20, the third long side 111 of the gate line 11 is partially covered by the welding strip 20, and the third long side 111 of the gate line 11 is partially protruding from the welding strip 20. In addition, the distance from the second long side 22 to the third long side 111 of the welding strip 20 is first reduced and then increased. Of course, in other embodiments, the distance from the second long side 22 to the third long side 111 of the welding strip 20 may also be set to be first increased and then reduced.

[0049] Furthermore, if Fig. 9 When the gate line 11 is covered by the welding strip 20, part of the third long side 111 of the gate line 11 may be covered by the welding strip 20, and part of the fourth long side 112 of the gate line 11 may be covered by the welding strip 20. That is, part of the gate line 11 protrudes from the welding strip 20, part of the third long side 111 of the gate line 11 is covered by the welding strip 20, part of the third long side 111 of the gate line 11 protrudes from the welding strip 20, part of the fourth long side 112 of the gate line 11 is covered by the welding strip 20, and part of the fourth long side 112 of the gate line 11 protrudes from the welding strip 20. In addition, the distance from the first long side 21 to the fourth long side of the welding strip 20 first decreases and then increases, and the distance from the second long side 22 to the third long side 111 of the welding strip 20 first decreases and then increases; of course, in other embodiments, the distance from the first long side 21 to the fourth long side of the welding strip 20 can also be set to first increase and then decrease, and the distance from the second long side 22 to the third long side 111 of the welding strip 20 can also be set to first increase and then decrease.

[0050] That is, in the embodiment of the present invention, there can be multiple ways for the welding strip 20 to cover the gate line 11, so as to achieve the effect of improving the flexibility of setting the welding strip 20 in the back contact battery assembly 100. In addition, it can be understood that if the welding strip 20 is used Figure 6 The electrical contact between the gate wire and the solder strip is better, and the carrier collection effect is better. Figure 6If the solution is adopted Figure 7 , Figure 8 , Fig. 9 In the solution, the width of the soldering ribbon can be set narrower, thereby reducing the area of ​​the battery cell covered by the soldering ribbon and improving the battery efficiency.

[0051] For further information, please refer to Figure 3 , Figure 4 and Figure 5 Regarding the arrangement of the welding strip 20, in a possible implementation manner, the welding strip 20 extends along a third direction, and the angle between the first direction and the third direction is an acute angle.

[0052] Specifically, each welding strip 20 is arranged in sequence along the second direction and extends along the third direction, and each grid line 11 extends along the first direction, and the angle between the first direction and the third direction is an acute angle. The welding strip 20 and the grid line 11 can be arranged at an acute angle, so that the welding strip 20 and the grid line 11 are arranged at an acute angle to alleviate the problem of stress concentration, so as to ensure that the connection between the welding strip 20 and the battery cell 10 is stable, thereby achieving the effect of improving the connection stability between the welding strip 20 and the battery cell 10.

[0053] Moreover, in the back-contact battery assembly 100 in the embodiment of the present invention, the welding strip 20 is actively tilted at an acute angle to the grid line 11, which can reduce the process difficulty of the back-contact battery assembly 100, reduce the alignment requirements during welding, improve the fault tolerance and accuracy of welding, and reduce manufacturing complexity. The tilted setting method is easier to operate automated equipment, improves production efficiency, reduces manual intervention, and achieves the effect of reducing production costs. In addition, the design of the welding strip 20 tilted at an acute angle also helps to disperse the mechanical stress of the back-contact battery assembly 100, thereby reducing the stress concentration of the welding point and improving the reliability and durability of the welding point.

[0054] For further information, please refer to Figure 3 , Figure 4 and Figure 5 In a possible implementation manner, along the first direction, the distance L between at least a portion of the first long side 21 of the soldering strip 20 and the gate line 11 covered by the soldering strip 20 is 1 The distance L between at least a portion of the second long side 22 of the soldering strip 20 and the gate line 11 covered by the soldering strip 20 is 2 Satisfies the following relationship: L 1 +L 2 =d / cosα, wherein d is the width of the solder strip 20, and α is the angle between the first direction and the third direction, and α is specifically an acute angle.

[0055] In this way, the inclination angle of the welding ribbon 20 can be obtained according to the width of the welding ribbon 20. Therefore, the angle can be adjusted for different lengths and types of battery strings 200, so that one welding ribbon 20 can completely cover multiple battery cells 10, and in the specific process preparation of the back contact battery assembly 100, the process preparation can be facilitated and the preparation efficiency of the back contact battery assembly 100 can be improved.

[0056] Furthermore, for each soldering ribbon 20, L 1 and L 2 For example, along the first direction, different L 1 +L 2 The value of is a constant, which is always equal to d / cosα. Therefore, the relationship between the width of the soldering strip 20, the distance between the side length of the soldering strip 20 and the gate line 11, and the angle between the soldering strip 20 and the gate line 11 can be obtained. In this way, the layout of the soldering strip 20 can be optimized to ensure the electrical performance and mechanical stability of the soldering strip 20.

[0057] Furthermore, along the first direction, L 1 The absolute value of the increase in L 2 The absolute value of the reduction value is the same. Specifically, because the L of each welding strip 20 1 and L 2 For example, along the first direction, different L 1 +L 2 The value of is a constant. Therefore, corresponding to L 1 With L 2 That is, inversely proportional, when L 1 When L increases 2 That is, the corresponding decrease, and L 1 The absolute value of the increase in L 2 The absolute value of the reduction is the same; correspondingly, when L 1 When L decreases 2 That is, the corresponding increase, and L 1 The absolute value of the reduction is related to L 2 The absolute value of the increase is the same.

[0058] So, L 1 The value change of L 2 The numerical changes of L 1 When increasing, L 2 will decrease by the same amount, or, when L 1 When L 2 will increase by the same amount accordingly, thus maintaining L 1 +L 2In this way, the distance between the soldering ribbon 20 and the grid line 11 can be kept stable, the layout of the soldering ribbon 20 can be optimized, and the space of the back contact battery assembly 100 can be effectively utilized to optimize the current transmission path.

[0059] Further, in a possible implementation manner, as Figure 3 , Figure 4 and Figure 5 As shown, for each battery cell 10, a first doping layer 121 and a second doping layer 122 are provided on the second surface 12 of the battery cell 10, the first doping layer 121 and the second doping layer 122 extend along the first direction and are alternately distributed along the second direction; the welding strip 20 electrically connects the first doping layer 121 of the battery cell 10 and the second doping layer 122 of the adjacent battery cell 10 respectively.

[0060] Specifically, the first doping layer 121 and the second doping layer 122 are doping layers with different doping polarities. Because the first doping layer 121 and the second doping layer 122 also extend along the first direction, the soldering strip 20 and the doping layer are also arranged at an acute angle. Therefore, by arranging the soldering strip 20 and the doping layer to be arranged at an acute angle, the contact area between the soldering strip 20 and the battery cell 10 is increased, and then the electrical contact area between the soldering strip 20 and the doping layer is increased, so as to achieve the effect of improving the conductive efficiency from the doping layer to the soldering strip 20.

[0061] In the embodiment of the present invention, the doping types of the first doping layer 121 and the second doping layer 122 are not limited. For example, the first doping layer 121 and the second doping layer 122 can be a P-type doping layer and an N-type doping layer, respectively; or the first doping layer 121 can be an N-type doping layer, and the second doping layer 122 can be a P-type doping layer, and the polarity of the two can be different to meet different needs. In some embodiments, the first doping layer 121 can be a P-type polycrystalline silicon layer, a P-type amorphous silicon layer, or a P-type microcrystalline silicon layer, which is not specifically limited here. Similarly, the second doping layer 122 can be an N-type polycrystalline silicon layer, an N-type amorphous silicon layer, or an N-type microcrystalline silicon layer, which is not specifically limited here. When the first doping layer 121 is a P-type doping layer and the second doping layer 122 is an N-type doping layer, a P-type gate line 11 can also be provided on the corresponding first doping layer 121, and an N-type gate line 11 can also be provided on the corresponding second doping layer 122, which is not specifically limited here.

[0062] In some embodiments, P-type doping refers to doping with Group III elements, including boron, aluminum, gallium, indium, thallium and other elements; N-type doping refers to doping with Group V elements, including nitrogen, phosphorus, arsenic, antimony, bismuth and other elements, which are not specifically limited here.

[0063] In addition, in some embodiments, the first doping layer 121 and the second doping layer 122 may also be composite doping, for example, N-type doping also includes a small amount of P-type doping elements. The content of the N-type doping element in the second doping layer 122 is higher than 20% of the content of the P-type doping element to ensure that the polarity is different from that of the first doping layer 121.

[0064] For further information, see Figure 3 , Figure 4 and Figure 5 In some possible implementations, for the angle α, the angle α between the first direction and the third direction satisfies the following relationship: 0<tanα≤D / T;

[0065] Wherein, T is the total length of the farthest ends of the first cell 10 and the last cell 10 in the cell string 200 along the first direction, and D is the width of any doping layer of the cell 10 along the second direction.

[0066] Therefore, through the above relationship, the inclination angle of the welding strip 20 can be obtained according to the length of the battery string 200, and the angle can be adjusted for battery strings 200 of different lengths and types, so that one welding strip 20 can completely cover the doping layers on the same straight line of multiple battery cells 10, so as to achieve the effect of facilitating process preparation.

[0067] For example, the battery string 200 may be 7 battery cells 10 evenly distributed along the first direction, and D is the distance between the farthest ends of the 7 battery cells 10. The inclination angle α is calculated based on the length and the width of the doped layer in the second direction, so that the welding strip 20 can be tilted at the angle α.

[0068] Therefore, in the embodiment of the present invention, a plurality of calculation methods of the angle α are provided, that is, the angle α can be calculated in a plurality of ways, thereby achieving the effect of improving the flexibility of the calculation of the angle α.

[0069] In addition, in the embodiment of the present invention, the angle range between the first direction and the third direction is not limited to meet different requirements. Therefore, the angle can be adjusted according to the length of different battery strings 200 and the width of the doping layer in the second direction.

[0070] Further, for the width of the doping layer, in a possible embodiment, the widths of the first doping layer 121 and the second doping layer in the second direction are equal. In this way, the first doping layer 121 and the second doping layer can be distributed, and the soldering strip 20 can be evenly arranged on the second surface 12 of the battery cell 10, so that the soldering strip 20 can be respectively arranged on the corresponding doping layer after being disconnected. The doping layer can be evenly distributed, and the soldering strip 20 can evenly cover the second surface 12 to ensure uniform extraction of current.

[0071] Further, in a possible embodiment, the center distance between two adjacent grid lines 11 is equal; the center distance between two adjacent grid lines 11 is equal to the center distance between two adjacent welding strips 20. Therefore, the grid lines 11 can be evenly arranged on the second surface 12 of the battery cell 10, and after the grid lines 11 are evenly distributed on the second surface 12 of the battery cell 10, the welding strips 20 can also be evenly distributed on the second surface 12 of the battery cell 10. Moreover, the center distance between adjacent welding strips 20 is equal to the center distance between adjacent grid lines 11, so that the welding strips 20 and the grid lines 11 can be accurately correspondingly arranged, ensuring that each grid line 11 can be effectively connected and welded.

[0072] In addition, in the embodiment of the present invention, equal center distances refer to "the distance between the structural centers of two adjacent structures is equal to the distance between the structural centers of another two adjacent structures". "Equal" in process preparation can be an allowable error ratio between 0.9 and 1.1, that is, when the rated center distance is 1, the maximum error distance can be 1.1 times the rated distance, and the minimum error distance can be 0.9 times the rated distance. Furthermore, for each welding strip 20, the multiple welding strips 20 are arranged in parallel. Therefore, the gate line 11 and the doping layer are arranged in parallel on the second side 12 of the battery cell 10, which can make the battery cell 10 more regular as a whole.

[0073] In some optional embodiments, the soldering strip 20 is in the shape of a long strip, and the width of the soldering strip 20 is less than the spacing between two adjacent gate lines 11. Therefore, when the soldering strip 20 is arranged on the battery cell 10, it can avoid the problem of a short circuit caused by a soldering strip 20 crossing two gate lines 11 of a battery cell 10 at the same time. Specifically, the width of a single soldering strip 20 is designed to be less than the spacing between two gate lines 11, which can ensure that when the soldering strip 20 is arranged, it will not cross and connect two adjacent gate lines 11 at the same time, thereby preventing the short circuit problem and achieving the effect of ensuring the safe and stable operation of the battery cell 10.

[0074] 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.

[0075] In addition, the above are only preferred embodiments of the present invention and are 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 assembly, characterized in that: include: A battery string, comprising a plurality of battery cells, wherein the battery cells have a first surface and a second surface opposite to each other, a plurality of grid lines are arranged on the second surface, the plurality of grid lines extend along a first direction and are arranged in sequence along a second direction, and the first direction and the second direction intersect; A plurality of welding strips, the welding strips connecting two adjacent battery cells, the welding strips being arranged in sequence along the second direction and covering the grid lines; the welding strips having a first long side and a second long side opposite to each other; Wherein, along the first direction, the distance from at least a portion of the first long side of the soldering strip to the gate line covered by the soldering strip gradually increases.

2. The back contact battery assembly according to claim 1, characterized in that: Along the second direction, the first sides of the plurality of grid lines are connected to form a third long side, the second sides of the plurality of grid lines are connected to form a fourth long side, and the third long side and the fourth long side are completely covered by the welding strip.

3. The back contact battery assembly according to claim 1, characterized in that: Along the second direction, the first sides of the plurality of gate lines are connected to form a third long side, the second sides of the plurality of gate lines are connected to form a fourth long side, the third long side is completely covered by the welding strip, and part of the fourth long side is covered by the welding strip.

4. The back contact battery assembly according to claim 1, characterized in that: Along the second direction, the first sides of the plurality of gate lines are connected to form a third long side, the second sides of the plurality of gate lines are connected to form a fourth long side, the fourth long side is completely covered by the welding strip, and part of the third long side is covered by the welding strip.

5. The back contact battery assembly according to claim 1, characterized in that: Along the second direction, the first sides of the plurality of gate lines are connected to form a third long side, the second sides of the plurality of gate lines are connected to form a fourth long side, part of the third long side is covered by the welding strip, and part of the fourth long side is covered by the welding strip.

6. The back contact battery assembly according to claim 1, characterized in that: Along the first direction, the distance from at least a portion of the second long side of the soldering strip to the gate line covered by the soldering strip gradually decreases.

7. The back contact battery assembly according to claim 6, characterized in that: The welding strip extends along a third direction, and an angle between the first direction and the third direction is an acute angle.

8. The back contact battery assembly according to claim 7, characterized in that: Along the first direction, a distance L1 from at least part of the first long side of the soldering strip to the gate line covered by the soldering strip and a distance L2 from at least part of the second long side of the soldering strip to the gate line covered by the soldering strip satisfy the following relationship: L1+L2=d / cosα; Wherein, d is the width of the welding strip, and α is the angle between the first direction and the third direction.

9. The back contact battery assembly according to claim 7, characterized in that: Along the first direction, the absolute value of the increase of L1 is the same as the absolute value of the decrease of L2.

10. The back contact battery assembly according to claim 6, characterized in that: The second surface is provided with a first doping layer and a second doping layer, the first doping layer and the second doping layer extend along the first direction and are alternately distributed along the second direction; The welding strips electrically connect the first doping layer of the battery cell and the second doping layer of the adjacent battery cell respectively.

11. The back contact battery assembly according to claim 7, characterized in that: The angle α between the first direction and the third direction satisfies the following relationship: 0<tanα≤D / T; Wherein, T is the total length of the farthest ends of the first cell and the last cell in the cell string along the first direction, and D is the width of any doping layer of the cell along the second direction.

12. The back contact battery assembly according to claim 1, characterized in that: The center distance between two adjacent gate lines is equal; the center distance between two adjacent gate lines is equal to the center distance between two adjacent welding strips.

13. The back contact battery assembly according to claim 1, characterized in that: The welding strip is in the shape of a long strip, and the width of the welding strip is smaller than the interval between two adjacent gate lines.

14. A photovoltaic system, characterized in that: Comprising a back contact battery assembly as claimed in any one of claims 1 to 13.

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