Main-grid-free back contact battery, battery assembly and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a main-grid-free back contact cell, a cell assembly and a photovoltaic system. The main-grid-free back contact battery is sequentially provided with a first edge region and a middle region along a first direction; according to the main-grid-free back contact battery, in the first edge area of the main-grid-free back contact battery, the area of the first fixing structures is gradually increased in the direction opposite to the first direction, the welding area is increased, the welding efficiency is improved, and the reliability of the main-grid-free back contact battery is improved. Stress and tension which are gradually increased when the main-grid-free back contact battery is closer to the edge are dispersed and resisted by gradually increasing welding tension of a welding strip and a fine grid which are closer to the edge of the main-grid-free back contact battery, so that the tension of the welding strip at the edge part is improved, the welding firmness of the welding strip is improved, the welding of the welding strip is stabilized, and the welding quality of the main-grid-free back contact battery is improved. And the cold solder joint risk of the solder strip is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of solar cells, in particular to a main-gridless back-contact battery, a battery module and a photovoltaic system. Background Art

[0002] In back-contact solar cells, in order to reduce the use of paste, the back-contact solar cells adopt a main-gridless design and directly weld the bus bar on the fine grid.

[0003] However, in such a technical solution, there is an easy phenomenon of poor welding between the bus bar welded on the edge part of the back-contact solar cell and the fine grid. Summary of the Utility Model

[0004] The utility model provides a main-gridless back-contact battery, a battery module and a photovoltaic system, aiming to solve the technical problem of poor welding of the bus bar welded on the edge part of the back-contact solar cell in the prior art.

[0005] The utility model is implemented as follows. A main-gridless back-contact battery is provided. The main-gridless back-contact battery is sequentially provided with a first edge area and a middle area along a first direction; in the first edge area, there are a plurality of first fine grids and a plurality of second fine grids, and the plurality of first fine grids and the plurality of second fine grids are alternately arranged at intervals in sequence; in the first edge area, there are a plurality of first fixing structures arranged on the first fine grid and / or the second fine grid, and each of the first fixing structures is arranged at intervals, and the first fixing structure is used for welding with the bus bar; in the first edge area, along the opposite direction of the first direction, the area of the first fixing structure gradually increases.

[0006] Furthermore, the main-gridless back-contact battery further has a second edge area. The main-gridless back-contact battery is sequentially provided with the first edge area, the middle area and the second edge area along the first direction; in the second edge area, there are a plurality of the first fine grids and a plurality of the second fine grids, and the plurality of the first fine grids and the plurality of the second fine grids are alternately arranged at intervals in sequence; in the second edge area, there are a plurality of second fixing structures arranged on the first fine grid and / or the second fine grid, and each of the second fixing structures is arranged at intervals, and the second fixing structure is used for welding with the bus bar; in the second edge area, along the first direction, the area of the second fixing structure gradually increases.

[0007] Furthermore, within the intermediate region, there are a number of the first fine grids and a number of the second fine grids, and the number of the first fine grids and the number of the second fine grids are arranged alternately and at intervals in sequence; within the intermediate region, there are a plurality of third fixing structures disposed on the first fine grid and / or the second fine grid, and each of the third fixing structures is disposed at intervals, and the third fixing structure is used for welding with a solder strip; within the intermediate region, along a first direction, the area of the third fixing structure remains unchanged.

[0008] Furthermore, the area of the first fixing structure is greater than or equal to the area of the third fixing structure.

[0009] Furthermore, the area of the second fixing structure is greater than or equal to the area of the third fixing structure.

[0010] Furthermore, the outer contour of the combination of a plurality of the first fixing structures is trapezoid-like.

[0011] Furthermore, the outer contour of the first fixing structure is trapezoid, circle, rectangle or octagon.

[0012] Furthermore, the outer contour of the first fixing structure is a trapezoid with the short side close to the intermediate region and the long side away from the intermediate region.

[0013] Furthermore, the outer contour of the combination of a plurality of the second fixing structures is trapezoid-like.

[0014] Furthermore, the outer contour of the second fixing structure is trapezoid, circle, rectangle or octagon.

[0015] Furthermore, the outer contour of the second fixing structure is a trapezoid with the short side close to the intermediate region and the long side away from the intermediate region.

[0016] Furthermore, the outer contour of the combination of a plurality of the third fixing structures is rectangle-like.

[0017] Furthermore, the outer contour of the third fixing structure is trapezoid, circle, rectangle or octagon.

[0018] Furthermore, the first fixing structure is also used for arranging a first solder paste layer; along the opposite direction of the first direction, the area of the first solder paste layer gradually increases.

[0019] Furthermore, the second fixing structure is also used for arranging a second solder paste layer; along the first direction, the area of the second solder paste layer gradually increases.

[0020] Furthermore, the third fixing structure is also used for arranging a third solder paste layer; along the first direction, the area of the third solder paste layer remains unchanged.

[0021] Further, in the first edge region, a first insulating adhesive is disposed between the first fixing structures corresponding to the adjacent first fine grids, and the first insulating adhesive is also disposed between the first fixing structures corresponding to the adjacent second fine grids. Along the opposite direction of the first direction, the area of the first insulating adhesive gradually increases.

[0022] Further, in the second edge region, a second insulating adhesive is disposed between the second fixing structures corresponding to the adjacent first fine grids, and the second insulating adhesive is also disposed between the second fixing structures corresponding to the adjacent second fine grids. Along the first direction, the area of the second insulating adhesive gradually increases.

[0023] Further, in the middle region, a third insulating adhesive is disposed between the third fixing structures corresponding to the adjacent first fine grids, and the third insulating adhesive is also disposed between the third fixing structures corresponding to the adjacent second fine grids. Along the first direction, the area of the third insulating adhesive remains unchanged.

[0024] Further, the first edge region further includes a plurality of doping layers, and the first fine grid or the second fine grid is correspondingly disposed on each doping layer; the first edge region has a first boundary along the second direction. In the first edge region, the doping type of the doping layer closest to the first boundary is opposite to the doping type of the silicon substrate in the main-gate-free back-contact battery, and the first direction is perpendicular to the second direction.

[0025] Further, the first edge region further includes a plurality of doping layers, and the first fine grid or the second fine grid is correspondingly disposed on each doping layer; the first edge region has a first boundary along the second direction. In the first edge region, the doping layer closest to the first boundary is a P-type doping layer, and the first direction is perpendicular to the second direction.

[0026] Further, the second edge region further includes a plurality of doping layers, and the first fine grid or the second fine grid is correspondingly disposed on each doping layer; the second edge region has a second boundary along the second direction. In the second edge region, the doping type of the doping layer closest to the second boundary is opposite to the doping type of the silicon substrate in the main-gate-free back-contact battery, and the first direction is perpendicular to the second direction.

[0027] Further, the second edge region further includes a plurality of doping layers, and the first fine grid or the second fine grid is correspondingly disposed on each doping layer; the second edge region has a second boundary along the second direction. In the second edge region, the doping layer closest to the second boundary is a P-type doping layer, and the first direction is perpendicular to the second direction.

[0028] The present utility model further provides a battery assembly, which includes a plurality of the main-gridless back-contact batteries described in any one of the above.

[0029] The present utility model further provides a photovoltaic system, which includes the above-mentioned battery assembly.

[0030] In the main-gridless back-contact battery, battery assembly and photovoltaic system according to the embodiments of the present utility model, the main-gridless back-contact battery is sequentially provided with a first edge area and an intermediate area along a first direction; in the first edge area, there are a plurality of first fine grids and a plurality of second fine grids, and the plurality of first fine grids and the plurality of second fine grids are alternately arranged at intervals in sequence; in the first edge area, there are a plurality of first fixing structures disposed on the first fine grids and / or the second fine grids, and each of the first fixing structures is disposed at intervals, and the first fixing structures are used for welding with a solder strip; in the first edge area, along the reverse direction of the first direction, the area of the first fixing structure gradually increases. In the first edge area of the main-gridless back-contact battery of the present utility model, the area of the first fixing structure is gradually increased along the reverse direction of the first direction, so as to increase the welding area, thereby gradually increasing the welding tensile force between the solder strip and the fine grid of the main-gridless back-contact battery closer to the edge, so as to disperse and resist the gradually increasing stress and tensile force of the main-gridless back-contact battery closer to the edge, achieving the effects of improving the tensile force of the solder strip in the edge part, improving the firmness of the solder strip welding, stabilizing the solder strip welding, and reducing the risk of solder strip virtual soldering.

[0031] The additional aspects and advantages of the present utility model will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a module schematic diagram of the photovoltaic system provided by the embodiment of the present utility model;

[0033] Figure 2 is a module schematic diagram of the battery assembly provided by the embodiment of the present utility model;

[0034] Figure 3 is a planar structure schematic diagram of the back surface of the main-gridless solar cell provided by an embodiment of the present utility model;

[0035] Figure 4 is Figure 3 a planar structure schematic diagram of the outer contour of the combination of a plurality of first fixing structures in the main-gridless solar cell chip in

[0036] Figure 5 is Figure 3 a planar structure schematic diagram of the outer contour of the combination of a plurality of second fixing structures in the main-gridless solar cell chip in

[0037] Figure 6 is Figure 3 a schematic plan view of the external contour of a combination of multiple third fixing structures in a main-gridless solar cell;

[0038] Figure 7 is a schematic plan view of the back side of a main-gridless solar cell according to an embodiment of the present invention, where the middle fixing structure is composed of multiple solder joints, and the fixing structure is composed of a single solder joint.

[0039] Figure 8 is a schematic plan view of the back side of a main-gridless solar cell according to an embodiment of the present invention, and the main-gridless solar cell is provided with solder paste;

[0040] Figure 9 is a schematic plan view of the back side of a main-gridless solar cell according to an embodiment of the present invention, and the main-gridless solar cell is provided with insulating glue;

[0041] Figure 10 is a schematic plan view of the back side of a main-gridless solar cell according to an embodiment of the present invention, and the main-gridless solar cell is provided with insulating glue and solder paste;

[0042] Figure 11 is Figure 3 a schematic diagram of the doping layer arrangement of a main-gridless solar cell;

[0043] Figure 12 is Figure 3 a partially enlarged schematic diagram of an arrangement of the doping layer near the first boundary in a main-gridless solar cell;

[0044] Figure 13 is Figure 3 a partially enlarged schematic diagram of another arrangement of the doping layer near the first boundary in a main-gridless solar cell;

[0045] Figure 14 is Figure 3 a partially enlarged schematic diagram of an arrangement of the doping layer near the second boundary in a main-gridless solar cell;

[0046] Figure 15 is Figure 3 a partially enlarged schematic diagram of another arrangement of the doping layer near the second boundary in a main-gridless solar cell;

[0047] Figure 16 is Figure 3 a schematic diagram of a way in which the area of the first fixing structure combination in a main-gridless solar cell gradually increases;

[0048] Figure 17 is Figure 3Schematic diagram of another way in which the area of the first fixed structure combination in the ownerless grid solar cell gradually increases;

[0049] Figure 18 is Figure 3 Schematic diagram of a way in which the area of the second fixed structure combination in the ownerless grid solar cell gradually increases;

[0050] Figure 19 is Figure 3 Schematic diagram of another way in which the area of the second fixed structure combination in the ownerless grid solar cell gradually increases.

[0051] Main component symbol description: 1000, photovoltaic system; 1001, battery module; 100, ownerless grid back contact battery; 200, first fine grid; 300, second fine grid; 400, doping layer; 410, P-type doping layer; 420, N-type doping layer; 10, first edge region; 11, first fixed structure; 12, first solder paste layer; 13, first insulating glue; 14, first boundary; 20, second edge region; 21, second fixed structure; 22, second solder paste layer; 23, second insulating glue; 24, second boundary; 30, middle region; 31, third fixed structure; 32, third solder paste layer; 33, third insulating glue. Detailed implementation manners

[0052] In order to make the objectives, technical solutions and advantages of the present utility model clearer and more understandable, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present utility model and should not be construed as a limitation to the present utility model. In addition, it should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0053] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "top", "bottom", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present utility model 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 thus should not be construed as a limitation to the present utility model.

[0054] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present utility model, "a plurality" means two or more unless otherwise specifically defined.

[0055] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, an electrical connection, or a connection that allows mutual communication; it may be a direct connection, or an indirect connection through an intermediate medium, and it may be the internal communication between two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0056] In the present utility model, unless otherwise clearly specified and defined, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over", and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "beneath", and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the horizontal height of the first feature is lower than that of the second feature.

[0057] The following disclosure provides many different embodiments or examples for implementing different structures of the present utility model. To simplify the disclosure of the present utility model, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present utility model. In addition, the present utility model may repeat reference numerals and / or reference letters in different examples. This 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 utility model provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use scenarios of other materials.

[0058] Please refer to Figure 1 and Figure 2 , the photovoltaic system 1000 in the embodiment of the present utility model may include the battery module 1001 in the embodiment of the present utility model. The battery module 1001 in the embodiment of the present utility model may include a plurality of battery strings, and the battery strings may include a plurality of main-gridless back-contact batteries 100 in the embodiment of the present utility model. In the present utility model, a plurality of main-gridless back-contact batteries 100 in the battery module 1001 may be sequentially connected in series through solder tapes to form a battery string. Each battery string in the battery module 1001 may be connected in series, in parallel, or in a series-parallel combination to achieve the current collection and output. For example, the connection between each battery string may be achieved through a bus bar.

[0059] Please refer toFigure 3 , in the embodiment of the present utility model, the main-gridless back-contact battery 100 has opposite front and back surfaces. A first edge region 10 and a middle region 30 are sequentially arranged on the back surface of the main-gridless back-contact battery 100 along a first direction. Specifically, as Figure 3 shown, the first direction may specifically be a direction horizontally to the right. Of course, in other embodiments, the first direction may also be other directions, such as a direction horizontally to the left, a diagonal direction, etc., which are not specifically limited herein.

[0060] As Figure 3 and Figure 4 shown, within the first edge region 10, there are a plurality of first fine grids 200 and a plurality of second fine grids 300. The plurality of first fine grids 200 and the second fine grids 300 are alternately arranged at intervals in sequence. Specifically, it may be set that the first fine grid 200 is a negative electrode fine grid and the second fine grid 300 is a positive electrode fine grid; or it may also be set that the first fine grid 200 is a positive electrode fine grid and the second fine grid 300 is a negative electrode fine grid, which is not limited herein.

[0061] Within the first edge region 10, there are a plurality of first fixing structures 11 arranged on the first fine grid 200 and / or the second fine grid 300. Each of the first fixing structures 11 is arranged at intervals. The first fixing structure 11 is used for welding with a solder strip. Specifically, the first fixing structure 11 is used for welding the solder strip on the first fine grid 200 and / or the second fine grid 300 within the first edge region 10. Within the first edge region 10, along the reverse direction of the first direction, the area of the first fixing structure 11 gradually increases.

[0062] For the manner in which the area of the first fixing structure 11 gradually increases, there can be various situations. For example, there are 6 first fixing structures 11 arranged in sequence along the reverse direction of the first direction, and the areas of each of the first fixing structures 11 are: X1, X2, X3, X4, X5, X6. As Figure 16 shown, it can be X1 < X2 < X3 < X4 < X5 < X6 such that the area of the first fixing structure 11 gradually increases, or, as Figure 17 shown, it can also be X1 = X2 < X3 = X4 < X5 = X6 such that the area of the first fixing structure 11 gradually increases, which is not limited herein.

[0063] Each of the first fixing structures 11 is specifically arranged at intervals on the first fine grid 200 and / or the second fine grid 300, and the first fixing structure 11 is used for welding the solder strip on the first fine grid 200 and / or the second fine grid 300 where the first fixing structure 11 is arranged. And as Figure 7 shown in the upper half of the main-gridless back-contact battery 100, the first fixing structure 11 may specifically be composed of a plurality of solder joints (which may also be called pad points), or as Figure 7As shown in the lower half of the main-grid-free back-contact battery 100, the first fixing structure 11 can also be formed by a relatively large solder joint.

[0064] For example, as Figure 7 shown in the upper half of the main-grid-free back-contact battery 100, the first fixing structure 11 can specifically be composed of a plurality of solder joints. The number of solder joints included in the first fixing structure 11 far from the middle region 30 is A, and the number of solder joints included in the first fixing structure 11 close to the middle region 30 is B, and A is greater than B. And along the opposite direction of the first direction, the number of solder joints in the first fixing structure 11 gradually increases.

[0065] Specifically, in the main-grid-free back-contact battery 100, since the stress and tensile force of the edge part are relatively concentrated, the tensile force of the solder tape welding in this part is insufficient, and it is easy to have false soldering. And the closer to the edge of the main-grid-free back-contact battery 100, the stronger the stress and tensile force, the more difficult it is to stably weld the solder tape, and the more likely it is to cause false soldering.

[0066] In the embodiment of the present invention, a first edge region 10 and a middle region 30 are sequentially arranged on the back surface of the main-grid-free back-contact battery 100 along the first direction. The first edge region 10 is an edge part in the main-grid-free back-contact battery 100. In the first edge region 10, the closer to the edge of the main-grid-free back-contact battery 100, the stronger the stress and tensile force, and it becomes more difficult to stably weld the solder tape, and the risk of false soldering increases.

[0067] Therefore, in the embodiment of the present invention, in the first edge region 10, the closer to the edge of the main-grid-free back-contact battery 100, the larger the area of the first fixing structure 11, increasing the welding area, so as to gradually increase the welding tensile force between the solder tape closer to the edge and the fine grid of the main-grid-free back-contact battery 100, to disperse and resist the gradually increasing stress and tensile force closer to the edge of the main-grid-free back-contact battery 100, achieving the effect of improving the tensile force of the solder tape in the edge part, improving the firmness of the solder tape welding, stabilizing the solder tape welding, and reducing the risk of false soldering of the solder tape.

[0068] Moreover, in the embodiment of the present invention, the area of the first fixing structure 11 does not uniformly match the stress and tensile force of the outermost edge part in the main-grid-free back-contact battery 100. Instead, it gradually increases in the first edge region 10 along the opposite direction of the first direction. This setting of gradually increasing the area of the first fixing structure 11 can, on the premise of ensuring the welding strength of the solder tape, achieve the effect of optimizing the use of materials and reducing costs.

[0069] Furthermore, in a possible implementation manner, as Figure 3 and Figure 4 shown, the outer contour of the combination of the plurality of first fixing structures 11 is trapezoid-like.

[0070] Specifically, since the stress and tensile force at the edge portion (the first edge region 10) of the main-grid-free back-contact battery 100 increase as the position approaches the edge. Therefore, in order to match the stress and tensile force in the first edge region 10, the area of the first fixing structure 11 in the present utility model can specifically vary in a gradient manner. The closer to the edge of the main-grid-free back-contact battery 100 (i.e., in the direction opposite to the first direction), the larger the area of the corresponding first fixing structure 11 is set. It gradually increases from a smaller area near the middle region 30 to a larger area near the edge. Therefore, the outer contour of the combination of the plurality of first fixing structures 11 is trapezoid-like. In the embodiment of the present utility model, the first edge region 10 is divided into multiple segments, and the area of the fixing structure within each segment gradually increases, so as to adapt to different stress requirements, and can effectively address the problems of high stress and large tensile force at the edge portion of the main-grid-free back-contact battery 100, improving the stability of the solder tape welding and the overall reliability of the main-grid-free back-contact battery 100.

[0071] Furthermore, in a possible implementation manner, the outer contour of the first fixing structure 11 can be trapezoid, circular, rectangular or octagonal. Specifically, the outer contours of the respective first fixing structures 11 can be set as trapezoid, circular, rectangular or octagonal, etc.

[0072] When the first fixing structure 11 is specifically set as a trapezoid, optionally, the outer contour of the first fixing structure 11 can be a trapezoid with the short side close to the middle region 30 and the long side away from the middle region 30.

[0073] Moreover, the solder tape is usually welded by solder paste. Therefore, further, in a possible implementation manner, as Figure 3 、 Figure 8 and Figure 10 shown, the first fixing structure 11 is also used to set a first solder paste layer 12. Along the direction opposite to the first direction, the area of the first solder paste layer 12 gradually increases. Of course, for the way in which the area of the first solder paste layer 12 gradually increases, it can be set with reference to the first fixing structure 11, and details will not be elaborated here.

[0074] The first solder paste layer 12 is specifically composed of solder paste, and the first solder paste layer 12 is used to weld the solder tape on the first fixing structure 11. And in order to address the stress and tensile force at the edge portion (the first edge region 10) of the main-grid-free back-contact battery 100 increasing as the position approaches the edge, so along the direction opposite to the first direction, the area of the first solder paste layer 12 set in the present utility model also gradually increases.

[0075] Among them, before specifically welding the welding ribbon, each first fixing structure 11 is correspondingly covered with a first solder paste layer 12. Optionally, in each first fixing structure 11, the coverage range of the first solder paste layer 12 does not exceed the area of the first fixing structure 11. Before welding the welding ribbon, the outer contour of the combination of multiple first solder paste layers 12 can also present a trapezoid-like shape. The outer contours of the respective first solder paste layers 12 can also be set as trapezoids, circles, rectangles, octagons or other irregular shapes, and specifically can be selected according to the actual situation, which is not limited here.

[0076] Furthermore, in the first edge region 10, as Figure 3 , Figure 9 and Figure 10 shown, in addition to the first fixing structure 11. In a possible implementation manner, in the first edge region 10, a first insulating adhesive 13 is used to be arranged between the first fixing structures 11 corresponding to adjacent first fine grids 200, and a first insulating adhesive 13 is used to be arranged between the first fixing structures 11 corresponding to adjacent second fine grids 300. Along the reverse direction of the first direction, the area of the first insulating adhesive 13 gradually increases. Of course, for the way of the gradual increase in the area of the first insulating adhesive 13, it can be set with reference to the first fixing structure 11, which will not be elaborated here.

[0077] Specifically, in addition to arranging the first fixing structure 11 on the first fine grid 200 and the second fine grid 300, the first insulating adhesive 13 can also be arranged on the first fine grid 200 and / or the second fine grid 300 in the first edge region 10. Specifically, the first insulating adhesive 13 is arranged between adjacent first fixing structures 11, or the first fixing structures 11 are arranged between adjacent first insulating adhesives 13.

[0078] In the first edge region 10, through the arrangement of each first fixing structure 11 and each first insulating adhesive 13, the first fine grid 200 with the same polarity can be welded to the welding ribbon, and the second fine grid 300 with the opposite polarity can be insulated from the welding ribbon; or the second fine grid 300 with the same polarity can be welded to the welding ribbon, and the first fine grid 200 with the opposite polarity can be insulated from the welding ribbon. For example, when the welding ribbon to be welded has the same polarity as the first fine grid 200 and the opposite polarity to the second fine grid 300, the welding ribbon is welded to the first fine grid 200 through the first fixing structure 11, and the welding ribbon is insulated from the second fine grid 300 through the first insulating adhesive 13; similarly, when the welding ribbon to be welded has the same polarity as the second fine grid 300 and the opposite polarity to the first fine grid 200, the welding ribbon is welded to the second fine grid 300 through the first fixing structure 11, and the welding ribbon is insulated from the first fine grid 200 through the first insulating adhesive 13.

[0079] In addition, in the back-contact battery 100 without a main grid, as Figure 3 ,Figure 11 , Figure 12 and Figure 13 As shown in Figure 11 , Figure 12 and Figure 13 , the fine grid is disposed on the doping layer 400. The first edge region 10 further includes a plurality of doping layers 400, and a first fine grid 200 or a second fine grid 300 is correspondingly disposed on each doping layer 400. The doping layer 400 may specifically be a P-type doping layer 410 or an N-type doping layer 420, and the P-type doping layer 410 and the N-type doping layer 420 are also alternately arranged. Specifically, the first fine grid 200 may be disposed on the P-type doping layer 410, and the second fine grid 300 may be disposed on the N-type doping layer 420; or, the second fine grid 300 may be disposed on the P-type doping layer 410, and the first fine grid 200 may be disposed on the N-type doping layer 420, which may be specifically selected according to actual situations and is not limited herein. The first edge region 10 has a first boundary 14 along the second direction, and the first direction is perpendicular to the second direction. In the present invention, the second direction is specifically the vertical direction, and the first boundary 14 is not only one of the boundaries of the first edge region 10, but also one of the boundaries of the entire main-gridless back-contact battery 100.

[0080] In a possible implementation manner, in the first edge region 10, the doping type of the doping layer 400 closest to the first boundary 14 is opposite to the doping type of the silicon substrate in the main-gridless back-contact battery 100, so as to achieve the effect of increasing the emitter area of the main-gridless back-contact battery 100 and improving the battery efficiency of the main-gridless back-contact battery 100.

[0081] In addition, for electrons and holes, it is more difficult to collect holes. Therefore, in the first edge region 10, setting the doping type of the doping layer 400 closest to the first boundary 14 to be opposite to the doping type of the silicon substrate in the main-gridless back-contact battery 100 can also achieve the effect of enhancing the hole collection ability of the main-gridless back-contact battery 100 at the edge portion.

[0082] For example, if the silicon substrate in the main-gridless back-contact battery 100 is P-type doped, as Figure 13 shown, that is, the doping layer closest to the first boundary 14 is an N-type doping layer 420; or, if the silicon substrate in the main-gridless back-contact battery 100 is N-type doped, as Figure 12 shown, that is, the doping layer closest to the first boundary 14 is a P-type doping layer 410.

[0083] Of course, as Figure 12 shown, in a possible implementation manner, optionally, the doping layer 400 closest to the first boundary 14 in the first edge region 10 is set as a P-type doping layer 410. To achieve the effect of enhancing the hole collection ability of the main-gridless back-contact battery 100 at the edge portion.

[0084] Furthermore, in a possible implementation manner, asFigure 3 and Figure 5 As shown in Figure 5 , the back surface of the main-gridless back-contact battery 100 further has a second edge region 20. Along a first direction, a first edge region 10, an intermediate region 30, and a second edge region 20 are sequentially arranged on the back surface of the main-gridless back-contact battery 100.

[0085] Similarly, within the second edge region 20, there are a plurality of first fine grids 200 and a plurality of second fine grids 300, and the plurality of first fine grids 200 and second fine grids 300 are alternately arranged at intervals in sequence. Specifically, the first fine grid 200 can be a negative fine grid, and the second fine grid 300 is a positive fine grid; or alternatively, the first fine grid 200 can be a positive fine grid, and the second fine grid 300 is a negative fine grid, which is not limited herein.

[0086] Within the second edge region 20, there are a plurality of second fixing structures 21 disposed on the first fine grid 200 and / or the second fine grid 300. Each of the second fixing structures 21 is disposed at intervals, and the second fixing structure 21 is used for welding with a solder strip. Specifically, the second fixing structure 21 is used for welding the solder strip on the first fine grid 200 and / or the second fine grid 300 within the second edge region 20. Within the second edge region 20, along the first direction, the area of the second fixing structure 21 gradually increases.

[0087] For the manner in which the area of the second fixing structure 21 gradually increases, there can be various situations. For example, there are 6 second fixing structures 21 arranged in sequence along the first direction, and the areas of each of the second fixing structures 21 are: Y1, Y2, Y3, Y4, Y5, Y6. As Figure 18 shown, it can be Y1 < Y2 < Y3 < Y4 < Y5 < Y6 such that the area of the second fixing structure 21 gradually increases, or, as Figure 19 shown, it can also be Y1 = Y2 < Y3 = Y4 < Y5 = Y6 such that the area of the second fixing structure 21 gradually increases, which is not limited herein.

[0088] As Figure 7 shown, each of the second fixing structures 21 is specifically disposed at intervals on the first fine grid 200 and / or the second fine grid 300, and the second fixing structure 21 is used for welding the solder strip on the first fine grid 200 and / or the second fine grid 300 where the second fixing structure 21 is disposed. And as Figure 7 shown in the upper half of the main-gridless back-contact battery 100 in Figure 7 , the second fixing structure 21 can specifically be composed of a plurality of solder joints; or, as Figure 7 shown in the lower half of the main-gridless back-contact battery 100 in Figure 7 , the second fixing structure 21 can also be composed of a relatively large solder joint.

[0089] For example, as Figure 7As shown in the upper half of the main-gridless back-contact battery 100, the second fixing structure 21 may specifically be composed of a plurality of solder joints. The number of solder joints included in the second fixing structure 21 far from the middle region 30 is C, and the number of solder joints included in the second fixing structure 21 close to the middle region 30 is D, where C is greater than D. And along the first direction, the number of solder joints in the second fixing structure 21 gradually increases.

[0090] In the embodiment of the present invention, a first edge region 10, a middle region 30, and a second edge region 20 are sequentially arranged along the first direction on the back surface of the main-gridless back-contact battery 100. The second edge region 20 is also an edge part of the main-gridless back-contact battery 100. Within the second edge region 20, the closer to the edge of the main-gridless back-contact battery 100, the stronger the stress and tension, making it more difficult to stably weld the solder tape and increasing the risk of virtual soldering.

[0091] Therefore, in the embodiment of the present invention, within the second edge region 20, the closer to the edge of the main-gridless back-contact battery 100, the larger the area of the second fixing structure 21, increasing the welding area to gradually increase the welding tension between the solder tape and the fine grid closer to the edge of the main-gridless back-contact battery 100, so as to disperse and resist the gradually increasing stress and tension closer to the edge of the main-gridless back-contact battery 100, achieving the effect of improving the solder tape tension at the edge part, enhancing the firmness of the solder tape welding, stabilizing the solder tape welding, and reducing the risk of virtual soldering of the solder tape.

[0092] Moreover, in the embodiment of the present invention, the area of the second fixing structure 21 does not uniformly match the stress and tension at the outermost edge part of the main-gridless back-contact battery 100. Instead, it gradually increases within the second edge region 20 along the first direction. This setting of gradually increasing the area of the second fixing structure 21 can achieve the effect of optimizing the use of materials and reducing costs while ensuring the welding strength of the solder tape.

[0093] Furthermore, in a possible implementation manner, as Figure 3 and Figure 5 shown, the outer contour of the combination of multiple second fixing structures 21 is trapezoid-like.

[0094] Specifically, because the stress and tension of the edge portion (second edge region 20) of the mainbar-free back contact battery 100 increase as the position approaches the edge. Therefore, in order to match the stress and tension of the second edge region 20, the area of ​​the second fixed structure 21 in the utility model can be specifically changed in a gradient. The closer to the edge of the mainbar-free back contact battery 100 (i.e., along the first direction), the larger the area of ​​the corresponding second fixed structure 21 is set, from a smaller area close to the middle region 30 to a larger area close to the edge, so the outer contour of the combination of multiple second fixed structures 21 is set to be a trapezoid. The embodiment of the utility model divides the second edge region 20 into multiple segments, and the area of ​​the fixed structure in each segment gradually increases, so as to adapt to different stress requirements, and can effectively deal with the high stress and large tension problems of the edge portion of the mainbar-free back contact battery 100, improve the stability of the welding strip welding and the overall reliability of the mainbar-free back contact battery 100.

[0095] Further, in a possible implementation, the outer contour of the second fixing structure 21 may be a trapezoid, a circle, a rectangle or an octagon. Specifically, the outer contour of each second fixing structure 21 may be set to be a trapezoid, a circle, a rectangle or an octagon.

[0096] When the second fixing structure 21 is specifically configured as a trapezoid, optionally, the outer contour of the second fixing structure 21 may be a trapezoid with a short side close to the middle area 30 and a long side away from the middle area 30 .

[0097] Moreover, the soldering strip is usually soldered by solder paste. Therefore, further, as Figure 3 , Figure 5 , Figure 8 and Figure 10 As shown, in a possible implementation, the second fixing structure 21 is also used to set the second solder paste layer 22, and the area of ​​the second solder paste layer 22 gradually increases along the first direction. Of course, the manner in which the area of ​​the second solder paste layer 22 gradually increases can be set with reference to the second fixing structure 21, and will not be repeated here.

[0098] The second solder paste layer 22 is specifically composed of solder paste, and the second solder paste layer 22 is used to solder the solder strip to the second fixed structure 21. In order to cope with the stress and tension of the edge portion (the second edge region 20) of the busbar-free back contact battery 100 increasing as the position approaches the edge, the area of ​​the second solder paste layer 22 provided in the utility model is gradually increased along the first direction.

[0099] Among them, before specifically welding the solder tape, each second fixing structure 21 is correspondingly covered with a second solder paste layer 22. Of course, in each second fixing structure 21, optionally, the coverage range of the second solder paste layer 22 does not exceed the area of the second fixing structure 21. Before welding the solder tape, the outer contour of the combination of multiple second solder paste layers 22 can also present a trapezoid-like shape. The outer contours of the respective second solder paste layers 22 can also be set to trapezoid, circular, rectangular, octagonal or other irregular shapes, and can be specifically selected according to the actual situation, which is not limited here.

[0100] Furthermore, in the second edge region 20, in addition to the second fixing structure 21. In a possible implementation manner, as Figure 3 , Figure 5 , Figure 9 and Figure 10 shown, in the second edge region 20, a second insulating adhesive 23 is provided between the second fixing structures 21 corresponding to adjacent first fine grids 200, and a second insulating adhesive 23 is provided between the second fixing structures 21 corresponding to adjacent second fine grids 300. Along the first direction, the area of the second insulating adhesive 23 gradually increases. Of course, for the way in which the area of the second insulating adhesive 23 gradually increases, it can be set with reference to the second fixing structure 21, which will not be elaborated here.

[0101] Specifically, in addition to providing the second fixing structure 21 on the first fine grid 200 and / or the second fine grid 300, the second insulating adhesive 23 can also be provided on the first fine grid 200 and / or the second fine grid 300 in the first edge region 10. Specifically, the second insulating adhesive 23 is provided between adjacent second fixing structures 21, or the second fixing structures 21 are provided between adjacent second insulating adhesives 23.

[0102] In the second edge region 20, through the arrangement of each second fixing structure 21 and each second insulating adhesive 23, the first fine grid 200 with the same polarity can be welded to the solder tape, and the second fine grid 300 with the opposite polarity can be insulated from the solder tape; or the second fine grid 300 with the same polarity can be welded to the solder tape, and the first fine grid 200 with the opposite polarity can be insulated from the solder tape. For example, when the solder tape to be welded has the same polarity as the first fine grid 200 and the opposite polarity to the second fine grid 300, the solder tape is welded to the first fine grid 200 through the second fixing structure 21, and the solder tape is insulated from the second fine grid 300 through the second insulating adhesive 23; similarly, when the solder tape to be welded has the same polarity as the second fine grid 300 and the opposite polarity to the first fine grid 200, the solder tape is welded to the second fine grid 300 through the second fixing structure 21, and the solder tape is insulated from the first fine grid 200 through the second insulating adhesive 23.

[0103] In addition, similarly, as Figure 3 ,Figure 5 , Figure 11 , Figure 14 and Figure 15 As shown in Figure 5 , Figure 11 , Figure 14 and Figure 15 , in the main-gridless back-contact cell 100, the fine grids are disposed on the doping layer 400. In a possible implementation, the second edge region 20 further includes a plurality of doping layers 400, and a first fine grid 200 or a second fine grid 300 is correspondingly disposed on each doping layer 400. The doping layer 400 may specifically be a P-type doping layer 410 or an N-type doping layer 420, and the P-type doping layer 410 and the N-type doping layer 420 are also alternately arranged. Specifically, the first fine grid 200 may be disposed on the P-type doping layer 410, and the second fine grid 300 may be disposed on the N-type doping layer 420; or, the second fine grid 300 may be disposed on the P-type doping layer 410, and the first fine grid 200 may be disposed on the N-type doping layer 420, which may be specifically selected according to actual situations and is not limited herein. The second edge region 20 has a second boundary 24 along the second direction, and the first direction and the second direction are perpendicular. In the present invention, the second direction is specifically the vertical direction, and the second boundary 24 is not only one of the boundaries of the second edge region 20, but also one of the boundaries of the entire main-gridless back-contact cell 100.

[0104] In a possible implementation, in the second edge region 20, the doping type of the doping layer closest to the second boundary 24 is opposite to the doping type of the silicon substrate in the main-gridless back-contact cell 100, so as to increase the emitter area of the main-gridless back-contact cell 100 and improve the cell efficiency of the main-gridless back-contact cell 100.

[0105] In addition, for electrons and holes, it is more difficult to collect holes. Therefore, in the second edge region 20, setting the doping type of the doping layer 400 closest to the second boundary 24 to be opposite to the doping type of the silicon substrate in the main-gridless back-contact cell 100 can also enhance the hole collection ability of the main-gridless back-contact cell 100 at the edge portion.

[0106] For example, the silicon substrate in the main-gridless back-contact cell 100 is P-type doped, as shown in Figure 14 , that is, the doping layer closest to the second boundary 24 is an N-type doping layer 420; or, the silicon substrate in the main-gridless back-contact cell 100 is N-type doped, as shown in Figure 15 , that is, the doping layer closest to the second boundary 24 is a P-type doping layer 410. Figure 14 shown, Figure 15 shown,

[0107] Of course, as shown in Figure 15 , in a possible implementation, optionally, the doping layer 400 closest to the second boundary 24 in the second edge region 20 may be set as a P-type doping layer 410, so as to enhance the hole collection ability of the main-gridless back-contact cell 100 at the edge portion. Figure 15 shown

[0108] Optionally, in the embodiments of the present utility model, the doping layer closest to the first boundary 14 may be set as an N-type doping layer 420, and / or the doping layer closest to the second boundary 24 may also be set as an N-type doping layer 420.

[0109] Furthermore, for the arrangement of the fixing structures in the middle part of the main-gridless back-contact battery 100. As Figure 3 and Figure 6 shown, furthermore, in a possible implementation manner, there are also a plurality of first fine grids 200 and a plurality of second fine grids 300 in the middle region 30, and the plurality of first fine grids 200 and second fine grids 300 are alternately arranged at intervals in sequence. Specifically, the first fine grid 200 may be a negative electrode fine grid, and the second fine grid 300 is a positive electrode fine grid; or alternatively, the first fine grid 200 may be a positive electrode fine grid, and the second fine grid 300 is a negative electrode fine grid, which is not limited herein.

[0110] There are a plurality of third fixing structures 31 provided on the first fine grid 200 and / or the second fine grid 300 in the middle region 30, and the respective third fixing structures 31 are arranged at intervals. The third fixing structure 31 is used for welding with a solder strip, and specifically, the third fixing structure 31 is used for welding the solder strip on the first fine grid 200 and / or the second fine grid 300 in the middle region 30. In the middle region 30, along the first direction, the area of the third fixing structure 31 remains unchanged.

[0111] Optionally, in a possible implementation manner, the area of the first fixing structure 11 in the first edge region 10 is greater than or equal to the area of the third fixing structure 31 in the middle region 30; the area of the second fixing structure 21 in the second edge region 20 is greater than or equal to the area of the third fixing structure 31 in the middle region 30.

[0112] Specifically, since the first edge region 10 and the second edge region 20 are respectively arranged on both sides of the middle region 30, by setting the area of the first fixing structure 11 in the first edge region 10 to be greater than or equal to the area of the third fixing structure 31 in the middle region 30, the problems of high stress and large tensile force in the edge part of the main-gridless back-contact battery 100 can be effectively addressed, further improving the stability of the solder strip welding and the overall reliability of the main-gridless back-contact battery 100; similarly, setting the area of the second fixing structure 21 in the second edge region 20 to be greater than or equal to the area of the third fixing structure 31 in the middle region 30 can effectively address the problems of high stress and large tensile force in the edge part of the main-gridless back-contact battery 100, further improving the stability of the solder strip welding and the overall reliability of the main-gridless back-contact battery 100.

[0113] As Figure 7As shown, each of the third fixing structures 31 is specifically arranged at intervals on the first fine grid 200 and the second fine grid 300, and the third fixing structure 31 is used to weld the solder tape on the first fine grid 200 or the second fine grid 300 provided with the third fixing structure 31. And as Figure 7 shown in the upper half of the main-gridless back-contact battery 100, the third fixing structure 31 can specifically be composed of a plurality of solder joints; or as Figure 7 shown in the lower half of the main-gridless back-contact battery 100, the third fixing structure 31 can also be composed of a relatively large solder joint.

[0114] For example, as Figure 7 shown in the upper half of the main-gridless back-contact battery 100, the third fixing structure 31 can specifically be composed of a plurality of solder joints. The number of solder joints included in the third fixing structure 31 is E, and along the first direction, the number of solder joints in the third fixing structure 31 remains unchanged.

[0115] Specifically, in the main-gridless back-contact battery 100, the middle region 30 is arranged between two edge regions. In the middle region 30, by setting the area of the third fixing structure 31 to be unchanged, a stable welding area is provided for the middle region 30 of the main-gridless back-contact battery 100, ensuring that the welded part in the middle region 30 has uniform mechanical strength and stability, and also achieving the effect of optimizing the use of materials and reducing costs. Among them, the outer contour of the combination of multiple third fixing structures 31 is rectangular, and the outer contour of each third fixing structure 31 can be trapezoidal, circular, rectangular or octagonal.

[0116] Moreover, the solder tape is usually welded by solder paste. Therefore, further, in a possible implementation manner, as Figure 3 、 Figure 6 、 Figure 8 and Figure 10 shown, the third fixing structure 31 is also used to set the third solder paste layer 32, and along the first direction, the area of the third solder paste layer 32 remains unchanged.

[0117] The third solder paste layer 32 is specifically composed of solder paste, and the third solder paste layer 32 can weld the solder tape on the third fixing structure 31. Similarly, by setting the area of the third solder paste layer 32 to be unchanged, a stable welding area is provided for the middle region 30 of the main-gridless back-contact battery 100, ensuring that the welded part in the middle region 30 has uniform mechanical strength and stability, and also achieving the effect of optimizing the use of materials and reducing costs.

[0118] Among them, before specifically welding the solder tapes, each third fixing structure 31 is correspondingly covered with a third solder paste layer 32. Of course, in each third fixing structure 31, the coverage range of the third solder paste layer 32 does not exceed the area of the third fixing structure 31. Before welding the solder tapes, the outer contour of the combination of multiple third solder paste layers 32 can also present a quasi-rectangle. The outer contours of the respective third solder paste layers 32 can also be set as trapezoids, circles, rectangles, octagons or other irregular shapes, and specific selections can be made according to the actual situation and are not limited here.

[0119] Furthermore, in the second edge region 20, in addition to the third fixing structure 31. In one possible implementation, as Figure 3 , Figure 6 , Figure 9 and Figure 10 shown, in the middle region 30, a third insulating adhesive 33 is provided between the third fixing structures 31 corresponding to adjacent first fine grids 200, and a third insulating adhesive 33 is provided between the third fixing structures 31 corresponding to adjacent second fine grids 300. Along the first direction, the area of the third insulating adhesive 33 remains unchanged.

[0120] Specifically, in addition to providing the third fixing structures 31 on the first fine grids 200 and the second fine grids 300, a third insulating adhesive 33 can also be provided on the first fine grids 200 and / or the second fine grids 300 in the second edge region 20. Specifically, the third insulating adhesive 33 is provided between adjacent third fixing structures 31, or the third fixing structures 31 are provided between adjacent third insulating adhesives 33.

[0121] In the middle region 30, through the settings of the respective third fixing structures 31 and the respective third insulating adhesives 33, the first fine grids 200 with the same polarity can be welded to the solder tape, and the second fine grids 300 with the opposite polarity can be insulated from the solder tape; or the second fine grids 300 with the same polarity can be welded to the solder tape, and the first fine grids 200 with the opposite polarity can be insulated from the solder tape. For example, when the solder tape to be welded has the same polarity as the first fine grid 200 and the opposite polarity to the second fine grid 300, the solder tape is welded to the first fine grid 200 through the third fixing structure 31, and the solder tape is insulated from the second fine grid 300 through the third insulating adhesive 33; similarly, when the solder tape to be welded has the same polarity as the second fine grid 300 and the opposite polarity to the first fine grid 200, the solder tape is welded to the second fine grid 300 through the third fixing structure 31, and the solder tape is insulated from the first fine grid 200 through the third insulating adhesive 33.

[0122] In addition, similarly, as Figure 3 , Figure 6 and Figure 11As shown, in the main-gridless back-contact battery 100, the fine grids are disposed on the doping layer 400. In a possible implementation, a plurality of doping layers 400 are further included therebetween, and a first fine grid 200 or a second fine grid 300 is correspondingly disposed on each doping layer 400. The doping layer 400 is specifically a P-type doping layer 410 or an N-type doping layer 420, and the P-type doping layer 410 and the N-type doping layer 420 are also alternately disposed. Specifically, the first fine grid 200 may be disposed on the P-type doping layer 410, and the second fine grid 300 may be disposed on the N-type doping layer 420; or, the second fine grid 300 may be disposed on the P-type doping layer 410, and the first fine grid 200 may be disposed on the N-type doping layer 420. Specific selection may be made according to actual situations and is not limited herein.

[0123] Therefore, in the main-gridless back-contact battery 100 of the present utility model, by providing a fixed structure that gradually increases in the reverse direction of the first direction in the edge region of the main-gridless back-contact battery 100, i.e., the first edge region 10, and providing a fixed structure that gradually increases in the first direction in the second edge region 20, the problem of gradually increasing stress and tensile force closer to the edge in the main-gridless back-contact battery 100 can be effectively addressed, achieving the effects of improving the stability of solder ribbon welding and the overall reliability of the main-gridless back-contact battery 100; and a third fixed structure 31 with a constant area is provided in the intermediate region 30 between the first edge region 10 and the second edge region 20, achieving the effects of ensuring uniform mechanical strength and stability in the intermediate region 30 and reducing costs.

[0124] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. 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 a suitable manner in any one or more embodiments or examples.

[0125] Although the embodiments of the present utility model have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present utility model. The scope of the present utility model is defined by the claims and their equivalents.

Claims

1. A busbar-free back contact battery, characterized in that: The busbar-free back contact battery is provided with a first edge region and a middle region in sequence along a first direction; A plurality of first fine grids and a plurality of second fine grids are provided in the first edge region, and the plurality of first fine grids and the plurality of second fine grids are alternately arranged in sequence; In the first edge region, a plurality of first fixing structures are arranged on the first fine grid and / or the second fine grid, each of the first fixing structures is arranged at intervals, and the first fixing structures are used for welding with the welding strip; In the first edge region, along the opposite direction of the first direction, the area of ​​the first fixing structure gradually increases.

2. The busbar-free back contact cell according to claim 1, characterized in that: The busbar-free back contact cell further comprises a second edge region, wherein the busbar-free back contact cell is sequentially provided with the first edge region, the middle region and the second edge region along a first direction; A plurality of the first fine grids and a plurality of the second fine grids are provided in the second edge region, and the plurality of the first fine grids and the plurality of the second fine grids are alternately arranged in sequence; In the second edge region, a plurality of second fixing structures are arranged on the first fine grid and / or the second fine grid, the second fixing structures are arranged at intervals, and the second fixing structures are used for welding with the welding strip; In the second edge region, along the first direction, the area of ​​the second fixing structure gradually increases.

3. The busbar-free back contact cell according to claim 2, characterized in that: A plurality of the first fine grids and a plurality of the second fine grids are provided in the middle region, and the plurality of the first fine grids and the plurality of the second fine grids are alternately arranged in sequence; A plurality of third fixing structures are provided in the middle region and are arranged on the first fine grid and / or the second fine grid, and the third fixing structures are arranged at intervals and are used for welding with the welding strip; In the middle region, along the first direction, the area of ​​the third fixing structure remains unchanged.

4. The busbar-free back contact cell according to claim 3, characterized in that: The area of ​​the first fixing structure is greater than or equal to the area of ​​the third fixing structure.

5. The busbar-free back contact cell according to claim 3, characterized in that: The area of ​​the second fixing structure is greater than or equal to the area of ​​the third fixing structure.

6. The busbar-free back contact cell according to claim 1, characterized in that: The outer contour of the plurality of first fixing structure combinations is trapezoidal.

7. The busbar-free back contact cell according to claim 1, characterized in that: The outer contour of the first fixing structure is trapezoidal, circular, rectangular or octagonal.

8. The busbar-free back contact cell according to claim 7, characterized in that: The outer contour of the first fixing structure is a trapezoid with a short side close to the middle area and a long side away from the middle area.

9. The busbar-free back contact cell according to claim 2, characterized in that: The outer contour of the combination of the plurality of second fixing structures is trapezoidal.

10. The busbar-free back contact cell according to claim 2, characterized in that: The outer contour of the second fixing structure is trapezoidal, circular, rectangular or octagonal.

11. The busbar-free back contact cell according to claim 10, characterized in that: The outer contour of the second fixing structure is a trapezoid with a short side close to the middle area and a long side away from the middle area.

12. The busbar-free back contact cell according to claim 3, characterized in that: The outer contour of the combination of the plurality of third fixing structures is quasi-rectangular.

13. The busbar-free back contact cell according to claim 3, characterized in that: The outer contour of the third fixing structure is trapezoidal, circular, rectangular or octagonal.

14. The busbar-free back contact cell according to claim 1, characterized in that: The first fixing structure is also used to set a first solder paste layer; Along the opposite direction of the first direction, the area of ​​the first solder paste layer gradually increases.

15. The busbar-free back contact cell according to claim 2, characterized in that: The second fixing structure is also used to set a second solder paste layer; Along the first direction, the area of ​​the second solder paste layer gradually increases.

16. The busbar-free back contact cell according to claim 3, characterized in that: The third fixing structure is also used to set a third solder paste layer; Along the first direction, the area of ​​the third solder paste layer remains unchanged.

17. The busbar-free back contact cell according to claim 1, characterized in that: In the first edge region, the first insulating glue is set between the first fixed structures corresponding to adjacent first fine grids, and the first insulating glue is set between the first fixed structures corresponding to adjacent second fine grids. The area of ​​the first insulating glue gradually increases in the opposite direction of the first direction.

18. The busbar-free back contact cell according to claim 2, characterized in that: In the second edge region, the second insulating glue is disposed between the second fixing structures corresponding to adjacent first fine grids, and the second insulating glue is disposed between the second fixing structures corresponding to adjacent second fine grids, and the area of ​​the second insulating glue gradually increases along the first direction.

19. The busbar-free back contact cell according to claim 3, characterized in that: In the middle area, a third insulating glue is disposed between the third fixing structures corresponding to adjacent first fine grids, and a third insulating glue is disposed between the third fixing structures corresponding to adjacent second fine grids, and the area of ​​the third insulating glue remains unchanged along the first direction.

20. The busbar-free back contact cell according to claim 1, characterized in that: The first edge region further includes a plurality of doped layers, and the first fine gate or the second fine gate is correspondingly arranged on each of the doped layers; The first edge region has a first boundary along a second direction. In the first edge region, the doping type of the doping layer closest to the first boundary is opposite to the doping type of the silicon substrate in the main gate-free back contact battery, and the first direction is perpendicular to the second direction.

21. The busbar-free back contact cell according to claim 1, characterized in that: The first edge region further includes a plurality of doped layers, and the first fine gate or the second fine gate is correspondingly arranged on each of the doped layers; The first edge region has a first boundary along a second direction, the doped layer closest to the first boundary in the first edge region is a P-type doped layer, and the first direction is perpendicular to the second direction.

22. The busbar-free back contact cell according to claim 2, characterized in that: The second edge region further includes a plurality of doped layers, and the first fine gate or the second fine gate is correspondingly arranged on each of the doped layers; The second edge region has a second boundary along a second direction. In the second edge region, the doping type of the doping layer closest to the second boundary is opposite to the doping type of the silicon substrate in the main gate-free back contact battery, and the first direction is perpendicular to the second direction.

23. The busbar-free back contact cell according to claim 2, characterized in that: The second edge region further includes a plurality of doped layers, and the first fine gate or the second fine gate is correspondingly arranged on each of the doped layers; The second edge region has a second boundary along a second direction. In the second edge region, the doped layer closest to the second boundary is a P-type doped layer, and the first direction is perpendicular to the second direction.

24. A battery assembly, characterized in that: A busbar-free back contact cell comprising any one of claims 1 to 23.

25. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 24.

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