Back-contact solar cells and solar modules

Abstract

The back-contact solar cell of the present invention includes a battery body including a central region and edge regions on both sides thereof; a fine grid including a collector fine grid and a bus fine grid, wherein the collector fine grid is provided in the central region such that it extends continuously along a first direction, and the bus fine grid is provided in the edge region such that it extends intermittently along the first direction; a connecting line provided in the edge region, including an intermediate connecting line and a side connecting line, wherein the pair of side connecting lines are provided at the edge positions on both sides of the battery body, and the intermediate connecting line is interposed between the pair of side connecting lines; and a plurality of welded structures electrically connected to the collector fine grid or the connecting line, wherein the width of the intermediate connecting line is greater than the width of the side connecting line. [Effect] This solves the problem of low carrier forwarding efficiency in routes connecting smaller grids using at least the main grid.

Description

Technical Field

[0001] This application relates to the field of solar cells, and particularly to back contact solar cells and solar cell modules.

Background Art

[0002] In photovoltaic technology, the most prominent feature of an interdigitated back contact (IBC) cell is that both the PN junction and the contact metal are located on the back of the IBC cell, and the front of the IBC cell completely avoids the shielding of the metal grid electrode, maximally utilizes the incident light, reduces optical losses, and can have a higher short-circuit current.

[0003] In related technologies, a back contact cell usually provides a main grid to connect fine grids of the same polarity, and then uses pads on the main grid to weld with a welding ribbon. However, carriers on the fine grids not connected to the pads need to be first transferred to the main grid and then transferred to the welding ribbon by the pads. The transfer path is long and the transfer efficiency of the carriers is low.

[0004] Therefore, how to design a back contact solar cell with high transfer efficiency is a problem to be solved by those skilled in the art.

Summary of the Invention

[0005] Embodiments of this application provide a back contact solar cell and a solar cell module to solve the problem that the transfer efficiency of carriers in the path of connecting fine grids using at least a main grid is low.

[0006] In some embodiments of the present disclosure, a back contact solar cell according to an aspect of an embodiment of this application includes a cell body having intersecting first and second directions and including a central region and edge regions located on both sides of the central region in the second direction, A grid line structure comprising collector fine grids and bus fine grids, wherein the collector fine grids and bus fine grids extend along a first direction, a plurality of the collector fine grids and a plurality of bus fine grids are sequentially arranged along a second direction, the collector fine grids are provided in the central region so as to extend continuously along the first direction, and the bus fine grids are provided in the edge region so as to extend intermittently along the first direction. A connection line provided within the edge region and electrically connected to a bus grid having the same polarity, comprising an intermediate connection line and a side connection line, wherein the intermediate connection line and the side connection line extend along the second direction, a pair of the side connection lines are provided at the edge positions on both sides of the battery body in the first direction, and the intermediate connection line is interposed between the pair of the side connection lines, The collection includes a plurality of welded structures electrically connected to the collector fine grid or the connecting wire, In the first direction, the width of the intermediate connecting line is greater than the width of the side connecting line.

[0007] In some embodiments, in the first direction, the width of the intermediate connecting line is a first width W1, the width of the side connecting line is a second width W2, and in the second direction, the width of the collector fine grid and bus fine grid is a third width W3, satisfying W1 > W2 > W3, 400 μm ≥ W1 ≥ 250 μm, and 250 μm ≥ W2 ≥ 50 μm.

[0008] In some embodiments, the welded structure is A first welded portion is provided on the side of the edge region adjacent to the central region and is electrically connected to a connecting wire having the same polarity, The system includes a second weld provided within the central region and electrically connected to the collector fine grid.

[0009] In some embodiments, gaps exist between adjacent bus grids that extend along the same straight line. The first weld is electrically connected to a bus microgrid in the edge region that is closest to the central region and has the same polarity, passes through a gap between adjacent bus microgrids with different polarities in a second direction, and is electrically connected to another bus microgrid or collector microgrid that has the same polarity.

[0010] In some embodiments, the first weld includes an intermediate weld and a side weld, the intermediate weld being electrically connected to the intermediate connecting wire, and the side weld being electrically connected to the side connecting wire. The connecting wire further includes an extension connecting wire. The distance between the side weld and the first edge corresponding to the side weld is greater than the distance between the side connection line electrically connected to the side weld and the first edge, and the side weld is electrically connected to the side connection line via the extension connection line extending along the first direction.

[0011] In some embodiments, in the second direction, the length of the side weld is a fourth length L4, and the spacing between adjacent bus grids or collector grids is spacing length g, satisfying 4g > L4 > 2g.

[0012] In some embodiments, in the second direction, the length of the intermediate weld is a third length L3, and the length of the side weld is a fourth length L4, satisfying L4 > L3.

[0013] In some embodiments, the bus grid includes a cutting grid provided on the side of the side weld toward the edge of the battery body corresponding to the side weld, The grid line structure further includes an extension connecting fine grid, the extension connecting fine grid extending along the second direction and provided on the side of the side weld toward the edge of the battery body corresponding to the side weld, and both ends of the extension connecting fine grid are electrically connected to bus fine grids having the same polarity as the cut grid.

[0014] In some embodiments, the edges of the battery body extending along the second direction are first edges, and the edges of the battery body extending along the first direction are second edges. The distance between one end of the connecting line along the second direction and the second edge corresponding to the connecting line is less than the distance between any bus grid electrically connected to the connecting line and the second edge. The distance between one end of a bus microgrid electrically connected to the side connection line along the first direction and the first edge corresponding to the bus microgrid is smaller than the distance between the side connection line and the first edge.

[0015] In some embodiments, the back-contact solar cell further includes auxiliary connection lines that penetrate the central region along the second direction and are electrically connected to the side connection lines on both sides, and are electrically connected to the collector fine grid having the same polarity.

[0016] In some embodiments, the edges of the battery body extending along the second direction are first edges, and the edges of the battery body extending along the first direction are second edges. The distance between one end of the collector fine grid electrically connected to the auxiliary connection line and the first edge is smaller than the distance between the auxiliary connection line and the first edge.

[0017] In some embodiments, in the first direction, the width of the side connecting line is the second width W2, the width of the auxiliary connecting line is the fifth width W5, and the following conditions are met: W2 > W5, 250 μm ≥ W2 ≥ 50 μm, and 200 μm ≥ W5 ≥ 30 μm.

[0018] In some embodiments of the present disclosure, another embodiment of the present application comprises a battery string in which a plurality of back-contact solar cells, which are back-contact solar cells as described in any one of the above paragraphs, are connected, A welding ribbon connecting adjacent back contact solar cells, A sealing adhesive film covering the surface of the back contact solar cell, Further provided is a solar cell module including a cover plate located on a surface of the sealing adhesive film away from the back contact solar cell.

[0019] The technical means according to the embodiments of the present application has at least the following advantages. In the present application, the grid line structure in the central region of the battery body is set as a collector fine grid, and the grid line structure in the edge region is set as a bus fine grid. Since the collector fine grid is directly electrically connected to the welding structure and the transfer path for the carriers collected by the collector fine grid to be transferred to the welding structure is short, the transfer efficiency of the carriers is improved.

Brief Description of the Drawings

[0020] One or more embodiments are exemplarily illustrated by the figures in the corresponding drawings. These exemplary descriptions do not limit the embodiments. Unless otherwise specified, the figures in the drawings do not limit the proportion. In order to more clearly explain the technical means in the embodiments of the present application or the prior art, the drawings necessary for the embodiments are briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present disclosure. A person skilled in the art can obtain other drawings based on these drawings without creative effort.

[0021] [Figure 1] It is a schematic configuration diagram of a back contact solar cell according to an embodiment of the present application. [Figure 2] It is a schematic configuration diagram of a back contact solar cell according to another embodiment of the present application.

Modes for Carrying Out the Invention

[0022] As can be seen from the background art, in the related art, usually, a main grid is provided and grid line structures of the same polarity are connected, and then a welding ribbon is welded using a welding structure on the main grid to reduce the number of welding structures. However, carriers on the grid line structure not connected to the welding structure in this structure need to be first transferred to the main grid and then transferred to the welding ribbon by the welding structure. Since the transfer efficiency of carriers on this path is low, it affects the photoelectric conversion efficiency of the back contact solar cell, and the cost of the slurry increases by providing the main grid.

[0023] In the back contact solar cell according to an embodiment of the present disclosure, the grid line structure in the central region of the battery body is set as a collector fine grid, and the grid line structure in the edge region is set as a bus fine grid. Since the collector fine grid is directly electrically connected to the welding structure and the transfer path for carriers collected by the collector fine grid to be transferred to the welding structure is short, the transfer efficiency of carriers is improved. The bus fine grids of the same polarity are electrically connected to the welding structure via connection lines, and the width of the intermediate connection line connecting the plurality of bus fine grids is larger than the width of the side connection line connecting the few bus fine grids provided on both sides. Since the internal resistance of the intermediate connection line with a large width is small, the transfer efficiency of carriers in the intermediate connection line is improved, and further the photoelectric conversion efficiency of the back contact solar cell is improved.

[0024] In the description of the embodiments of the present application, technical terms such as "first", "second", etc. are only used to distinguish different objects, and it cannot be understood that they indicate or imply relative importance, or implicitly indicate the number of the indicated technical features, a specific order or a primary-secondary relationship. In the description of the embodiments of the present application, "a plurality" means two or more unless there is a clear and specific limitation. Similarly, "a plurality of sets" refers to two or more sets (including two sets), and "a plurality of sheets" refers to two or more sheets (including two sheets).

[0025] The “Examples” as used herein mean that certain features, structures, or properties described in relation to the Examples may be included in at least one Example of the Application. The phrase “Examples” as used elsewhere in this Specification does not necessarily refer to the same Example, nor are they exclusive, independent, or alternative to other Examples. Those skilled in the art will understand, both explicitly and implicitly, that the Examples described herein can be combined with other Examples.

[0026] In the description of the embodiments of this application, the term "and / or" indicates a related relationship that describes related objects, and that there may be three possible relationships. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. Also, the letter " / " in this specification generally indicates that the related objects before and after are in an "or" relationship.

[0027] In the description of the embodiments of this application, the orientations or positional relationships indicated by technical terms such as "center," "vertical direction," "horizontal direction," "length," "width," "thickness," "top," "bottom," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," "axial direction," "radial direction," and "circumferential direction" are based on the orientations or positional relationships shown in the drawings and are merely for the purpose of easily describing and simplifying the description of the embodiments of this application. They do not indicate or suggest that the shown devices or parts have a specific orientation or must be configured and operated in a specific orientation, and should not be understood as limiting the embodiments of this application. For example, when a device or part in the drawing is inverted, a part described as "below," "underside," "below," or "bottom" of another part or feature is oriented "above" or "top" of the said other part or feature. Therefore, the term "below" may include two directions, up and down, depending on the context in which the term is used, which is obvious to those skilled in the art. The materials may be oriented in other ways (e.g., rotated 90 degrees, inverted, or flipped), and the spatially relative descriptive terms used herein may be interpreted accordingly.

[0028] In the description of the embodiments of this application, unless otherwise explicitly specified and limited, the technical terms "attachment," "connection," "bonding," and "fixing" should be understood in a broad sense. For example, these may be fixed connections, removable connections, or integral connections; they may be mechanical connections or electrical connections; they may be direct connections or indirect connections via an intermediate medium; and they may be internal communication between two parts or an interactive relationship between two parts. Those skilled in the art will be able to understand the specific meaning of these terms in the embodiments of this application according to the specific circumstances.

[0029] In the drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are shown enlarged for better understanding and to facilitate explanation. Furthermore, when it is stated that one component is formed "substantially" on the surface of another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on any part of the edge of the entire surface.

[0030] In the description of embodiments of this application, when one member "includes" another member, unless otherwise specified, this does not exclude other members, and other members may be included. Embodiments may include cases in which the second member is formed or provided above or on the first member, or on the surface of the first member, or on the side of the first member, and the first and second members are in direct contact, or embodiments may include cases in which the first and second members are not in direct contact by adding a member between them. For simplicity and clarity, various members may be drawn arbitrarily at different scales. In the drawings, some layers / members may be omitted for simplification. Unless otherwise specified, the formation or provision of the second member on the surface of the first member means that the first and second members are in direct contact. The above "member" may mean a layer, film, region, part, structure, etc.

[0031] The terms used in the description of the various embodiments described herein are intended solely to describe specific embodiments and are not intended to limit them. As used in the description of the various embodiments described and in the appended claims, “the members” is intended to be plural unless the context explicitly indicates otherwise. Members include members such as layers, films, regions, or plates.

[0032] The embodiments of this disclosure will be described in detail below with reference to the drawings. Those skilled in the art will understand that the embodiments of this disclosure provide many technical details to help the reader better understand the disclosure. However, the technical means seeking protection of this disclosure can be realized without these technical details or the various changes and modifications based on the embodiments below.

[0033] Figures 1 and 2 are schematic diagrams of a back-contact solar cell according to an embodiment of the present invention.

[0034] As shown in Figure 1, the back-contact solar cell includes a battery body 100, a grid line structure 200, and connecting wires 300.

[0035] The battery body 100 has intersecting first directions X and second directions Y, and includes a central region 110 and edge regions 120 located on both sides of the central region 110 in the second direction. The fine grid includes a collector fine grid 210 and a bus fine grid 220, the collector fine grid 210 and the bus fine grid 220 extending along a first direction X, a plurality of collector fine grids 210 and a plurality of bus fine grids 220 arranged sequentially along a second direction Y, the collector fine grid 210 being provided in a central region 110 so as to extend continuously along the first direction X, and the bus fine grid 220 being provided in an edge region 120 so as to extend intermittently along the first direction X. The connecting line 300 is provided within the edge region 120 and is electrically connected to the bus fine grid 220 having the same polarity, and includes an intermediate connecting line 310 and a side connecting line 320, the intermediate connecting line 310 and the side connecting line 320 extending along the second direction Y, the pair of side connecting lines 320 provided at the edge positions on both sides in the first direction X of the battery body 100, and the intermediate connecting line 310 is interposed between the pair of side connecting lines 320. In the first direction X, the width of the intermediate connecting line 310 is greater than the width of the side connecting line 320.

[0036] This invention divides the grid wire structure 200 of the battery body 100 into a collector fine grid 210 provided in the central region 110 and a bus fine grid 220 provided in the edge region 120. The collector fine grid 210 is directly electrically connected to the welded structure 400, and because the transfer path for carriers collected by the collector fine grid 210 to the welded structure 400 is short, the carrier transfer efficiency is improved. The bus fine grids 220 of the same polarity are electrically connected to the welded structure 400 via connecting wires 300, and the width of the intermediate connecting wires 310 that connect multiple bus fine grids 220 is greater than the width of the side connecting wires 320 provided on both sides and connecting fewer bus fine grids 220, and because the internal resistance of the wider intermediate connecting wires 310 is small, the carrier transfer efficiency within the intermediate connecting wires 310 is improved, and furthermore the photoelectric conversion efficiency of the back contact solar cell is improved. Providing connecting lines 300 in the edge region 120 reduces the number of welded structures 400 in the edge region 120, thereby avoiding the problem of cracking of the battery body 100 due to stress concentration during the welding process between the welded structure 400 and the welding ribbon, and the problem of warping of the battery body 100 due to the difference in expansion coefficients between the battery body 100 and the welding ribbon. This improves the yield rate of manufactured back-contact solar cells and extends the service life of back-contact solar cells.

[0037] The embodiments of this application will be described in more detail below with reference to the drawings.

[0038] Figure 1 shows a schematic configuration diagram of a back-contact solar cell according to an embodiment of the present invention. As shown in Figure 1, the back-contact solar cell has intersecting first direction X, second direction Y, and third direction. The positive and negative electrodes of the back-contact solar cell according to the embodiment of the present invention are both provided on one side of the back surface of the battery body 100. The back-contact solar cell includes the battery body 100, a grid line structure 200, connecting wires 300, and a welded structure 400.

[0039] The battery body 100 has a rectangular sheet-like structure and exhibits a photoelectric effect. The battery body 100 has a first surface and a second surface that face each other in a third direction, which is the thickness direction of the battery body 100. The first surface of the battery body 100 is the light-receiving surface of the back-contact solar cell of the embodiment of this application, and the second surface is the back surface of the back-contact solar cell. The grid line structure 200, the connecting lines 300, and the welding structure 400 are all provided on the second surface of the battery body 100. In the second direction Y, the battery body 100 has a first edge 101 that faces each other, and in the first direction X, the battery body 100 has a second edge 102 that faces each other. The battery body 100 includes a central region 110 and edge regions 120 provided on both sides of the central region 110 in the second direction Y, that is, the edge regions 120 on both sides are close to the opposing second edge 102 of the battery body 100.

[0040] In some embodiments, the grid line structure 200, connecting lines 300, and welded structure 400 are formed on the second surface of the battery body 100 by a screen printing process.

[0041] In some embodiments, the battery body 100 may be formed by dividing the entire battery cell into N parts, i.e., the battery body 100 is N divisions, where N is a positive integer greater than 1. In some other embodiments, the battery body 100 may consist of the entire battery cell, i.e., the battery body 100 is the whole.

[0042] In some embodiments, the battery body 100 is formed by dividing the entire battery cell into two parts; that is, the battery body 100 is two-part (half-slice).

[0043] In some embodiments, when the battery body 100 is formed by dividing the entire battery cell into N parts, the grid line structure 200, connecting lines 300, and welded structure 400 are first formed on the surface of the entire battery cell by a screen printing process, and then the entire battery cell is formed as an N division of the battery body 100 in the embodiment of the present application to constitute the back-contact solar cell in the embodiment of the present application. In another embodiment, the battery body 100 is a whole, and the grid line structure 200, connecting lines 300, and welded structure 400 are formed on the surface of the battery body 100 by a screen printing process to directly constitute the back-contact solar cell in the embodiment of the present application.

[0044] Multiple grid line structures 200 are provided on the second surface of the battery body 100 and collect and transfer photogenerated carriers to realize electrical energy conversion of the back-contact solar cell. Since both the positive and negative electrodes of the back-contact solar cell in the embodiment of the present application are provided on the back surface of the battery body 100, the polarity of the grid line structure 200 may be that of the positive or negative electrode. The grid line structure 200 includes collector fine grids 210 and bus fine grids 220. The collector fine grids 210 and bus fine grids 220 extend along a first direction X, and collector fine grids 210 and bus fine grids 220 with different polarities are distributed at intervals along a second direction Y. The collector fine grids 210 are provided within the central region 110 and are provided continuously along the first direction X. The polarity between adjacent collector fine grids 210 in the second direction Y is different. The bus grids 220 are provided within the edge region 120, intermittently along the first direction X, extending along the same straight line, and gaps 2201 exist between adjacent bus grids 220. The polarity of bus grids 220 extending along the same straight line is the same, while the polarity of adjacent bus grids 220 in the second direction Y is different. In the boundary region between the central region 110 and the edge region 120, the polarity of adjacent collector grids 210 and bus grids 220 in the second direction Y is different.

[0045] The connecting wire 300 is provided within the edge region 120 to collect carriers transferred by the collector fine grid 210. The connecting wire 300 extends along the second direction Y, and the polarity of the connecting wire 300 may be positive or negative, and the connecting member is electrically connected to the bus fine grid 220 which has the same polarity. The connecting wire 300 includes an intermediate connecting wire and a side connecting wire 320. Within the same edge region 120, the two side connecting wires 320 are provided symmetrically on both sides of the edge region 120 in the second direction Y, that is, the side connecting wires 320 on both sides are close to the opposing first edges 101 of the battery body 100, and the bus fine grid 220 and the intermediate connecting wire 310 are interposed between the symmetrical side connecting wires 320. The intermediate connection line 310 sequentially passes through the gaps 2201 between bus grids 220 with different polarities along the second direction Y, and is electrically connected to bus grids 220 that are provided on both sides in the second direction Y and have the same polarity. The side connection line 320 extends along the second direction Y and is electrically connected to bus grids 220 that are provided on one side of the side connection line 320 and have the same polarity.

[0046] The side connection lines 320 and the intermediate connection lines 310 are arranged uniformly at equal intervals in the second direction Y such that the lengths of the bus grids 220 connected to the side connection lines 320 on both sides are equal, and the lengths of the bus grids 220 connected to both sides of the intermediate connection line 310 in the second direction Y are equal. By uniformly arranging the side connection lines 320 and the intermediate connection lines 310, the internal resistance of the entire back-contact solar cell is reduced, the carrier transport efficiency is improved, and the photoelectric conversion efficiency of the back-contact solar cell is further improved.

[0047] Furthermore, in the first direction X, the width of the intermediate connection line 310 is the first width W1, and the width of the side connection line 320 is the second width W2, satisfying W1 > W2. The side connection line 320 is provided at an edge position close to the first edge 101 of the battery body 100, and only one side of the side connection line 320 is electrically connected to the bus fine grid 220, while both sides of the intermediate connection line 310 are electrically connected to the bus fine grid 220. Therefore, the total length of the bus fine grid 220 electrically connected to the side connection line 320 is smaller than the total length of the bus fine grid 220 electrically connected to the intermediate connection line 310, and the intermediate connection line 310 needs to transfer more units of carriers than the side connection line 320. The intermediate connection line 310 has a larger width dimension than the side connection line 320, which reduces the internal resistance of the intermediate connection line 310, improves the carrier transport efficiency of the intermediate connection line 310, and further improves the photoelectric conversion efficiency of the back contact solar cell. Compared to designs in related technologies in which the width dimension of the main grid (corresponding to the connecting line 300 in the embodiment of this application) connected to the fine grid (corresponding to the grid line structure 200 in the embodiment of this application) is wide, narrow, or the same, the embodiment of this application makes the width of the intermediate connecting line 310 greater than the width of the side connecting line 320, based on the overall length of the bus fine grid 220 connected to the intermediate connecting line 310 and the side connecting line 320 and the total mobility of the carriers to be transported, thereby improving the carrier transport efficiency and further improving the photoelectric conversion efficiency of the back contact solar cell, while saving slurry for manufacturing the connecting line 300 and reducing manufacturing costs.

[0048] In some embodiments, the first width W1 of the intermediate connecting wire 310 satisfies 250 μm ≤ W1 ≤ 400 μm. Preferably, the first width W1 of the intermediate connecting wire 310 may be 280 μm, 300 μm, 350 μm, or 370 μm.

[0049] In some embodiments, the second width W2 of the side connecting wire 320 satisfies 50 μm ≤ W2 ≤ 250 μm. Preferably, the second width W2 of the side connecting wire 320 may be 60 μm, 100 μm, 150 μm, or 200 μm.

[0050] In some embodiments, in the first direction X, the width of the collector fine grid 210 and the bus fine grid 220 is a third width W3, satisfying 15 μm ≤ W3 ≤ 50 μm. Preferably, the third width W3 of the collector fine grid 210 and the bus fine grid 220 may be 25 μm, 30 μm, 35 μm, or 40 μm.

[0051] Furthermore, at the point where the bus grid 220, which has the same polarity, is connected to the connecting line 300, the bus grid 220 is connected by crossing the connecting line 300.

[0052] In some embodiments, in the first direction X, the distance between one end of the bus microgrid 220 connected to the side connection line 320 that is close to the first edge 101 and the first edge 101 is smaller than the distance between the side connection line 320 and the first edge 101. In other words, the end of the bus microgrid 220 has the same polarity as the bus microgrid 220 and protrudes from the connected side connection line 320. In the second direction Y, the distance between one end of the connection line 300 that is close to the second edge 102 and the second edge 102 is smaller than the distance between the bus microgrid 220 that has the same polarity and is closest to the second edge 102 and the second edge 102. In other words, the end of the connection line 300 has the same polarity and protrudes from the bus microgrid 220 that has the same polarity and is closest to the second edge 102. Specifically, a bus grid 220 extending in the first direction X is connected to the bus grid 220 and passes through the connecting line 300 closest to the first edge 101, and a connecting line 300 extending in the second direction Y is connected to the connecting line 300 and passes through the bus grid 220 closest to the second edge 102. This cross-connection structure ensures a connection effect between the bus grid 220 and the connecting line 300, and avoids problems of unconnected or poorly connected bus grid 220 and connecting line 300 due to printing errors.

[0053] Furthermore, in the second direction Y, a certain distance exists between the end of the intermediate connection line 310 that is close to the second edge 102 and the bus grid 220 that has a different polarity and is closest to the second edge 102. In other words, the end of the intermediate connection line 310 that is close to the second edge 102 does not protrude from the straight line where the bus grid 220 that has a different polarity and is closest to the second edge 102 is located. That is, the intermediate connection line 310 and the bus grid 220 that has a different polarity and is closest to the second edge 102 are separated from each other in the second direction Y, and this separation structure avoids short-circuit problems that occur in the connection between the two due to printing errors.

[0054] Multiple welded structures 400 are provided on the second surface of the battery body 100 and are electrically connected to the collector fine grid 210 or the connecting wire 300. The welded structures 400 are welded to the welding ribbon and guide the current generated by the back-contact solar cells to the external circuit, realizing series-parallel connections between the back-contact solar cells and forming a complete current path.

[0055] The welded structure 400 includes a first weld 410 and a second weld 420. The first weld 410 is located within the edge region 120 and is electrically connected to the connecting line 300 within the edge region 120, while the second weld 420 is located within the central region 110 and is electrically connected to the collector fine grid 210 within the central region 110. Carriers collected by the bus fine grid 220 are sequentially transferred to the external circuit via the connecting line 300 and the first weld 410, thereby reducing the number of welded structures 400 located within the edge region 120. This avoids the problem of cracking of the battery body 100 due to stress concentration during the welding process between the welded structure 400 and the welding ribbon, and the problem of warping of the battery body 100 due to the difference in expansion coefficients between the battery body 100 and the welding ribbon, thereby improving the yield rate of the manufactured back-contact solar cells and extending the service life of the back-contact solar cells. The carriers collected by the collector fine grid 210 are directly transferred to the external circuit by the second weld 420. Because the transfer path is short, the carrier transfer efficiency is improved, and furthermore, the photoelectric conversion efficiency of the back-contact solar cell in the embodiment of the present invention is improved.

[0056] The first welds 410 and the second welds 420, which have the same polarity, are sequentially arranged along the second direction Y so as to be welded to a welding ribbon that extends in the second direction Y and has the same polarity. The second welds 420, which have the same polarity, are uniformly distributed according to the number of first welds 410, and the second welds 420, which have the same polarity and are adjacent to the second direction Y, are alternately distributed in the first direction X so as to be uniformly distributed within the central region 110, further avoiding the occurrence of warping or cracking problems due to welding of the battery body 100.

[0057] By arranging the first welds 410 sequentially at equal intervals along the first direction X, the internal stress of the battery body 100 is uniformly distributed after the first welds 410 and the second welds 420 are welded to the welding ribbon, thereby avoiding the occurrence of problems such as warping or cracking due to localized concentration of internal tension in the battery body 100.

[0058] The first welded joint 410 is located at an end position adjacent to the central region 110 of the connecting wire 300, that is, on the side away from the second edge 102 of the edge region 120, further avoiding the occurrence of warping or cracking problems at the edge position of the battery body 100.

[0059] Furthermore, in the first direction X, the width dimension of the first weld 410 and the width dimension of the second weld 420 are equal so that the first weld 410 and the second weld 420 can be formed synchronously during the printing process in the production process.

[0060] In the second direction Y, the length dimension of the first weld 410 is the first length L1, and the length dimension of the second weld 420 is the second length L2, satisfying L1 > L2. The total length of the bus fine grid 220 connected to the first weld 410 is greater than the length of the collector fine grid 210 connected to the second weld 420, and the length dimension of the first weld 410 is greater than the length dimension of the second weld 420, thereby providing high carrier transfer efficiency.

[0061] In some embodiments, the first length L1 of the first welding portion 410 satisfies 0.4 mm ≤ L1 ≤ 2.1 mm. Preferably, the first length L1 of the first welding portion 410 may be 0.8 mm, 1 mm, 1.2 mm, or 1.4 mm.

[0062] In some embodiments, the second length L2 of the second welding portion 420 satisfies 0.08 mm ≤ L2 ≤ 0.4 mm. Preferably, the second length L2 of the second welding portion 420 may be 0.15 mm, 0.2 mm, 0.25 mm, or 0.3 mm.

[0063] Furthermore, in the second direction Y, the length dimension of the intermediate welding portion 411 is the third length L3, and the length dimension of the side welding portion 412 is the fourth length L4, satisfying L3 < L4. Since the position where the side welding portion 412 is provided is closer to the edge position of the battery body 100 and its length dimension is larger than that of the second welding portion 420, the length dimension of the side welding portion 412 is increased to increase the welding tensile force after the side welding portion 412 and the welding ribbon are connected, thereby improving the stability of the overall structure of the back-contact solar cell.

[0064] In some embodiments, the third length L3 of the intermediate welding portion 411 satisfies 0.4 mm ≤ L3 ≤ 0.8 mm. Preferably, the third length L3 of the intermediate welding portion 411 may be 0.5 mm, 0.6 mm, 0.65 mm, or 0.7 mm.

[0065] In some embodiments, the fourth length L4 of the side welding portion 412 satisfies 0.8 mm ≤ L4 ≤ 2.1 mm. Preferably, the fourth length L4 of the side welding portion 412 may be 0.95 mm, 1 mm, 1.2 mm, or 1.4 mm.

[0066] Furthermore, in the second direction Y, the spacing between adjacent collector fine grids or between adjacent bus fine grids 220 is the spacing length g, and the length of the side weld 412 is the fourth length L4, satisfying 4g > L4 > 2g. Because the length of the side weld 412 is greater than twice the spacing length and less than four times the spacing length, the side weld 412 can penetrate the gap 2201 between bus fine grids with different polarities and electrically connect to the bus fine grid 220 or collector fine grid 210 with the same polarity. This direct electrical connection of the side weld 412 to the bus fine grid 220 or collector fine grid 210 shortens the length of the carrier transport path, improves the carrier transport efficiency, and further improves the photoelectric conversion efficiency of the back contact solar cell.

[0067] In some embodiments, the spacing dimension between adjacent collector fine grids 210 or the spacing length g between adjacent bus fine grids 220 satisfies 0.5 mm ≤ g ≤ 2 mm. Preferably, the spacing dimension between adjacent collector fine grids 210 or the spacing length g between adjacent bus fine grids 220 may be 0.8 mm, 0.92 mm, 1 mm, or 1.2 mm.

[0068] The first weld 410 includes an intermediate weld 411 and a side weld 412, the intermediate weld 411 being electrically connected to an intermediate connecting line 310 and the side weld 412 being electrically connected to a side connecting line 320. The intermediate weld 411 and the side weld 412, located in the same side region, are sequentially arranged along the first direction X.

[0069] In the first direction X, the distance between the side weld 412 and the first edge 101 corresponding to the side weld 412 is smaller than the distance between the side connecting line 320 and the first edge 101. As a result, the side weld 412 is further away from the first edge 101 than the side connecting line 320, further avoiding the occurrence of warping or cracking problems at the edge position of the battery body 100.

[0070] The connecting wire 300 further includes an extension connecting wire 330, which extends along a first direction X, and is provided between the side weld 412 and the side connecting wire 320, with both ends of the extension connecting wire 330 electrically connected to the side weld 412 and the side connecting wire 320, respectively.

[0071] Furthermore, in the second direction Y, the width of the extension connection line 330 is the fourth width W4, and the width of the side connection line 320 is the second width W2, satisfying W2 = W4. The width dimension of the extension connection line 330 is equal to the width dimension of the side connection line, avoiding an increase in the internal resistance of the side connection line 320 and the extension connection line 330 as a whole due to the width dimension of the extension connection line 330 being too small, and reducing the transport efficiency of the side connection line 320 to the carrier.

[0072] The bus grid 220 further includes a cutting grid 221 provided on the side adjacent to the first edge 101 of the side weld 412, and an extension connecting grid 230 connecting the cutting grid 221 and the bus grid 220. The bus grid 220, which has the same polarity as the cutting grid 221, extends along a first direction X, and the extension connecting grid 230 extends along a second direction Y, and is electrically connected to the cutting grid 221 and adjacent bus grids 220 or collector grids 210 that have the same polarity as the cutting grid 221. By providing the cutting grid 221 and the extension connecting grid 230, the coverage of the grid line structure 200 on the surface of the battery body 100 is improved, and the photoelectric conversion efficiency of the back contact solar cell is further improved.

[0073] In some embodiments, when the cutting grid 221 is interposed between the side connection line 320 and the side weld 412, the extension connecting fine grid 230 connects the cutting grid 221 and the bus fine grid 220, and penetrates the gap between the bus fine grid 220 adjacent to the cutting grid 221 and the side connection line 320, and which has a different polarity. In some embodiments, when the cutting grid 221 is provided on the side of the side weld 412 that is close to the first edge 101 and is not interposed by the side connection line 320, the extension connecting fine grid 230 connects the cutting grid 221 and the collector fine grid 210, and extends along the second direction Y on the side that is close to the first edge 101.

[0074] Figure 2 shows a schematic configuration diagram of a back-contact solar cell according to another embodiment of the present invention. As shown in Figure 2, in the other embodiment, the back-contact solar cell further includes auxiliary connection lines 340 provided on both sides adjacent to the first edge 101 of the battery body 100, extending along the second direction Y, and passing through the central region 110 and electrically connected to the side connection lines 320 on both sides. The collector fine grid 210 within the central region 110 extends toward the auxiliary connection lines 340 which have the same polarity, so that the auxiliary connection lines 340 are electrically connected to collector fine grids 210 which have the same polarity within the central region 110. By providing the auxiliary connection lines 340, carriers collected by the bus fine grid 220 via the edge connection lines 300 are not only transferred to the external circuit by the side welds 412, but may also be transferred to the external circuit by the second welds 420 on the collector fine grid 210, thereby reducing the internal resistance of the entire back-contact solar cell, improving the carrier transfer efficiency, and further improving the photoelectric conversion efficiency of the back-contact solar cell.

[0075] Furthermore, the auxiliary connection line 340 intersects and is connected to the collector fine grid 210. That is, the distance between one end electrically connected to the auxiliary connection line 340 of the collector fine grid 210 and the first edge 101 is smaller than the distance between the auxiliary connection line 340 and the first edge 101. This intersection connection structure ensures the connection effect between the collector fine grid 210 and the auxiliary connection line 340, and avoids the occurrence of problems such as non-connection or poor connection between the collector fine grid 210 and the auxiliary connection line 340 due to printing errors.

[0076] In the first direction X, the fifth width W5 of the auxiliary connection line 340 (where the width of the auxiliary connection line 340 is the fifth width W5), the second width W2 of the side connection line 320, and the third width W3 of the collector fine grid 210 and the bus fine grid 220 satisfy W2 > W5 > W3. By setting the widths based on the carrier mobilities collected and transferred by the side connection line 320, the auxiliary connection line 340, the collector fine grid 210, and the bus fine grid 220, while avoiding the problem of high internal resistance caused by a small uniform size, on the other hand, avoid the problem of excessive slurry usage and high manufacturing cost caused by a large uniform size. The setting of the widths of the side connection line 320, the auxiliary connection line 340, the collector fine grid 210, and the bus fine grid 220 improves the carrier transport efficiency, further improves the photoelectric conversion efficiency of the back contact solar cell, and reduces the manufacturing cost.

[0077] In some embodiments, the fifth width W5 of the auxiliary connection line 340 satisfies 30μm < W5 < 200μm. Preferably, the fifth width W5 of the auxiliary connection line 340 may be 50μm, 70μm, 85μm, or 110μm.

[0078] Accordingly, another embodiment of the present disclosure further provides a solar cell module comprising a battery string, a welding ribbon, a sealing adhesive film, and a cover plate. The battery string is formed by connecting a plurality of back-contact solar cells, which are the same as the back-contact solar cells in the above embodiment; the welding ribbon connects adjacent back-contact solar cells; the sealing adhesive film covers the surface of the back-contact solar cells; and the cover plate is located on the surface of the sealing adhesive film away from the back-contact solar cells. For parts that are the same as or corresponding to the previous embodiment, refer to the corresponding description of the above embodiment, and a detailed description is omitted below.

[0079] In some embodiments, when the battery body 100 is formed by dividing the entire battery cell into N parts, the grid line structure 200, connecting lines 300 and welded structure 400 are first formed on the surface of the entire battery cell by a screen printing process, and then the entire battery cell is formed as N divisions of the battery body 100 in the embodiments of the present invention to constitute a back-contact solar cell, and adjacent back-contact solar cells are connected by welded ribbons to constitute a battery string. In another embodiment, the battery body 100 is a whole, and the grid line structure 200, connecting lines 300 and welded structure 400 are formed on the surface of the battery body 100 by a screen printing process to directly constitute a back-contact solar cell, and adjacent back-contact solar cells are connected by welded ribbons to constitute a battery string.

[0080] The material for the sealing adhesive film may be an organic sealing adhesive film such as an ethylene-vinyl acetate copolymer (EVA) adhesive film, a polyethylene octencoelastomer (POE) adhesive film, or a polyvinyl butyral (PVB) adhesive film.

[0081] The cover plate may be a light-transmitting cover plate, such as a glass cover plate or a plastic cover plate. In some embodiments, the utilization rate of incident light can be improved by making the surface of the cover plate facing the adhesive film an uneven surface.

[0082] Those skilled in the art will understand that the embodiments described above are specific examples of realizing the Disclosure, and that in actual application, various changes can be made in form and detail without departing from the spirit and scope of the Disclosure. Since various changes and modifications can be made without departing from the spirit and scope of the Disclosure, the scope of protection of the Disclosure should be limited to the claims. [Explanation of symbols]

[0083] 100 Battery Unit 101 First Edge 102 Second Edge 110 Central area 120 Edge Area 200 grid line structure 210 collector fine grid 220 Bus Narrow Grid 2201 Gap 221 Cutting grid 230 Extension Connection Fine Grid 300 connecting wires 310 Intermediate connection line 320 Side connection line 330 Extension connection cable 340 Auxiliary connection wire 400 Welded Structure 410 First Weld 411 Intermediate weld 412 Side weld 420 Second Weld

Claims

1. A battery body (100) having a first direction (X) and a second direction (Y) that intersect, and including a central region (110) and edge regions (120) located on both sides of the central region (110) in the second direction (Y), A collector fine grid (210) and a bus fine grid (220), wherein the collector fine grid (210) is provided within the central region (110), the bus fine grid (220) is provided within the edge region (120), the collector fine grid (210) and the bus fine grid (220) extend along the first direction (X), and a plurality of the collector fine grid (210) and the plurality of bus fine grids (220) are sequentially arranged along the second direction (Y), An intermediate connection line (310) and a side connection line (320) provided within the edge region (120) and electrically connected to a bus fine grid (220) having the same polarity, wherein the intermediate connection line (310) and the side connection line (320) extend along the second direction (Y), and a pair of the side connection lines (320) are provided at edge positions on both sides of the battery body (100) extending along the first direction (X), and the intermediate connection line (310) is interposed between the pair of the side connection lines (320), It includes an auxiliary connection line (340) that penetrates the central region (110) along the second direction (Y) and is electrically connected to the side connection line (320) located on both sides of the central region (110), In the first direction (X), the width of the side connecting line (320) is greater than the width of the auxiliary connecting line (340). The edges at both ends of the battery body (100) extending along the second direction (Y) are first edges (101), The distance between one end of the collector fine grid (210) electrically connected to the auxiliary connection line (340) and the first edge (101) is smaller than the distance between the auxiliary connection line (340) and the first edge (101). A back-contact solar cell characterized by the following features.

2. In the first direction (X), the width of the side connecting line (320) is the second width W2, and the width of the auxiliary connecting line (340) is the fifth width W5. Satisfying 250 μm ≥ W2 ≥ 50 μm and 200 μm ≥ W5 ≥ 30 μm, The back-contact solar cell according to feature 1.

3. In the first direction (X), the width of the intermediate connecting line (310) is greater than the width of the side connecting line (320). The back-contact solar cell according to feature 1.

4. In the first direction (X), the width of the intermediate connecting line (310) is the first width W1, and the width of the side connecting line (320) is the second width W2. In the second direction (Y), the width of the collector fine grid (210) and the bus fine grid (220) is the third width W3. The following conditions are met: W1 > W2 > W3, 400 μm ≥ W1 ≥ 250 μm, 250 μm ≥ W2 ≥ 50 μm, and 50 μm ≥ W3 ≥ 15 μm. The back-contact solar cell according to feature 3.

5. The system includes a plurality of welded structures (400) electrically connected to the collector fine grid (210), the intermediate connecting wire (310), or the side connecting wire (320), The aforementioned welded structure (400) is A first welded portion (410) is provided on the side of the edge region (120) adjacent to the central region (110) and is electrically connected to the intermediate connecting line (310) or the side connecting line (320) having the same polarity, A second weld (420) provided within the central region (110) and electrically connected to the collector fine grid (210) is included, The back-contact solar cell according to feature 1.

6. The bus grid (220) extends intermittently along the first direction (X), A gap (2201) exists between adjacent bus grids (220) that extend along the same straight line. The first weld (410) is electrically connected to a bus fine grid (220) in the edge region (120) that is closest to the central region (110) and has the same polarity, passes through a gap (2201) between adjacent bus fine grids (220) in the second direction (Y) that have different polarities, and is electrically connected to another bus fine grid (220) or collector fine grid (210) that has the same polarity. The back-contact solar cell according to feature 5.

7. Further comprising an extension connecting wire (330), The first welded portion (410) includes an intermediate welded portion (411) and a side welded portion (412), The intermediate weld (411) is electrically connected to the intermediate connecting wire (310), and the side weld (412) is electrically connected to the side connecting wire (320). The distance between the side weld (412) and the first edge (101) corresponding to the side weld is greater than the distance between the side connecting wire (320) electrically connected to the side weld (412) and the first edge (101). The side weld portion (412) is electrically connected to the side connecting line (320) via the extension connecting line (330) which extends along the first direction (X). The back-contact solar cell according to feature 5.

8. In the second direction (Y), the length of the side weld (412) is the fourth length L4. The spacing between adjacent collector fine grids (210) or between bus fine grids (220) is the spacing length g. Satisfying 4g > L4 > L2g, The back-contact solar cell according to feature 7.

9. In the second direction (Y), the length of the intermediate weld (411) is the third length L3, and the length of the side weld (412) is the fourth length L4, satisfying L4 > L3. The back-contact solar cell according to feature 7.

10. The bus fine grid (220) includes a cutting grid (221) provided on the side of the side weld (412) toward the edge of the battery body (100) corresponding to the side weld (412), Further including an extension connection fine grid (230), The extension connecting fine grid (230) extends along the second direction (Y) and is provided on the side of the side weld (412) toward the edge of the battery body (100) corresponding to the side weld (412). Both ends of the extension connection fine grid (230) are electrically connected to bus fine grids (220) which have the same polarity as the cut grid (221). The back-contact solar cell according to feature 8.

11. The edges at both ends of the battery body (100) extending along the second direction (Y) are first edges (101), The edges at both ends of the battery body (100) extending along the first direction (X) are second edges (102), The distance between one end of the intermediate connection line (310) in the second direction (Y) and the second edge (102) corresponding to the connection line is smaller than the distance between any bus fine grid (220) electrically connected to the connection line and the second edge (102). The distance between one end of the bus fine grid (220) electrically connected to the side connection line (320) along the first direction (X) and the first edge (101) corresponding to the bus fine grid (220) is smaller than the distance between the side connection line (320) and the first edge (101). The back-contact solar cell according to feature 1.

12. The auxiliary connecting wire (340) is electrically connected to the collector fine grid (210) which has the same polarity. The back-contact solar cell according to feature 1.

13. The edges at both ends of the battery body (100) extending along the first direction (X) are second edges (102), The back-contact solar cell according to feature 12.

14. A battery string comprising a plurality of back-contact solar cells, each being a back-contact solar cell according to any one of claims 1 to 13, electrically connected; A welding ribbon connecting adjacent back contact solar cells, A sealing adhesive film covering the surface of the back contact solar cell, The sealing adhesive film includes a cover plate located on the surface away from the back contact solar cell, A solar cell module characterized by the following features.

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