Back contact photovoltaic cell and preparation method thereof, laminated cell and photovoltaic module

Abstract

The embodiment of the invention relates to the field of photovoltaic cells, and provides a back contact photovoltaic cell and a preparation method thereof, a laminated cell and a photovoltaic module, and the back contact photovoltaic cell comprises a cell piece body which is provided with a first surface; the welding part, the fine grid and the second connecting line are arranged on the first surface; the welding part comprises a middle welding part and edge welding parts, and the middle welding part is arranged between a pair of opposite edge welding parts in the first direction; the fine grids intermittently extend along a first direction; the second connecting lines extend along a second direction, and the edge welding parts are electrically connected with the fine grids with the same polarity through the second connecting lines; wherein one end, close to the fine grid, of the second connecting line is narrower than the other end. The embodiment of the invention is at least beneficial to improving the photoelectric conversion efficiency.

Description

Cross-reference to related applications

[0001] This application is a divisional application of Chinese invention patent application filed on October 21, 2025, with application number 202511508346.7 and invention title "Back Contact Photovoltaic Cell and its Preparation Method, Tandem Cell, Photovoltaic Module". Technical Field

[0002] This application relates to the field of photovoltaic cells, and in particular to a back-contact photovoltaic cell and its preparation method, a tandem cell, and a photovoltaic module. Background Technology

[0003] With the gradual depletion of fossil fuels, photovoltaic (PV) cells are becoming increasingly widely used as a new energy alternative. A PV cell is a device that converts solar energy into electrical energy. PV cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using electrodes, thus facilitating the efficient use of electrical energy. To further reduce the shading of the front side of PV cells by the grid lines, research on BC cells (Back Contact) is becoming increasingly in-depth.

[0004] The most significant feature of BC batteries is that the PN junction and contact metal are both located on the back of the BC battery. The front of the BC battery completely avoids the obstruction of the metal grid electrodes, which can maximize the use of incident light, reduce optical loss, and have a higher short-circuit current. Summary of the Invention

[0005] This application provides a back-contact photovoltaic cell and its preparation method, a tandem cell, and a photovoltaic module, which at least helps to improve the photoelectric conversion efficiency of the back-contact photovoltaic cell.

[0006] This application provides a back-contact photovoltaic cell, comprising: a cell body having intersecting first, second, and third directions; the cell body having opposing first and second surfaces in the third direction; the third direction being the thickness direction of the cell body; a welding portion disposed on the first surface; the welding portion including a middle welding portion and edge welding portions, the middle welding portion being disposed between opposing edge welding portions in the first direction; a fine grid disposed on the first surface, the fine grid extending discontinuously along the first direction, and a plurality of fine grids being sequentially spaced along the second direction; a second connecting line disposed on the first surface, the second connecting line extending along the second direction, the edge welding portions being electrically connected to the fine grids of the same polarity via the second connecting line; wherein, the width of the second connecting line at one end near the fine grid is smaller than the width at the other end.

[0007] Optionally, it further includes: a main grid, the main grid being disposed on the first surface, the main grid extending along the second direction, and a plurality of main grids being sequentially spaced along the first direction; the main grid includes a middle main grid and edge main grids, the middle main grid being disposed between a pair of opposing edge main grids in the first direction; the corresponding edge main grids and the edge welding portions are staggered in the first direction; Optionally, the width of the second connecting line near the fine grid is 8μm~15μm, and the width of the second connecting line near the edge welding portion is 8μm~20μm.

[0008] Optionally, the second connecting line crosses the fine grid that it contacts, and at least a portion of the second connecting line extends to the side of the fine grid that it contacts, away from the edge weld portion.

[0009] Optionally, the length of the second connecting line extending to the other side of the fine grid is 50μm~130μm.

[0010] Optionally, the ratio between the width of one end of the second connecting line near the edge welded portion that contacts it and the width of the other end of the second connecting line is 1 to 1.5.

[0011] Optionally, the first surface has opposing first edges in the first direction; the back contact photovoltaic cell further includes: a short grid disposed on the first surface, the short grid extending along the first direction, the short grid being disposed between the first edge and the edge weld portion; a first connecting line extending along the second direction, the first connecting line being disposed between the first edge and the edge weld portion, the short grid and the adjacent fine grid of the same polarity being electrically connected through the first connecting line; wherein, the width of the first connecting line at one end near the short grid is smaller than the width at the other end.

[0012] Optionally, the width of the first connecting line in the first direction gradually increases in the direction away from the short gate it contacts.

[0013] Optionally, the ratio between the width of the first connecting line at one end close to the fine grid and the width at the other end of the first connecting line is 1 to 1.5.

[0014] Optionally, the width of the first connecting line near the end of the fine gate that is in contact with it is 8μm to 20μm, and the width of the first connecting line near the end of the short gate that is in contact with it is 8μm to 15μm.

[0015] Optionally, the first connecting line is cross-connected to the fine gate and / or the short gate in contact with it, and at least a portion of the first connecting line extends to the side of the fine gate away from the short gate, and / or at least a portion of the first connecting line extends to the side of the short gate away from the fine gate.

[0016] Optionally, the length of the first connecting line extending to the other side of the fine gate or the short gate is 50 μm to 130 μm.

[0017] Optionally, the material of the first connecting line is the same as that of the main gate, and the first connecting line and the fine gate and / or the short gate are separate structures; and / or, the edge welding part that contacts and connects the second connecting line to it is an integral structure.

[0018] This application also provides a method for preparing a back-contact photovoltaic cell, comprising: providing a cell body, the cell body having opposing first surfaces and second surfaces in a third direction; the cell body having opposing first edges in a first direction; the first direction, the second direction and the third direction intersecting, the third direction being the thickness direction of the cell body; A plurality of welding portions and a second connecting line are formed on the first surface. The welding portions include intermediate welding portions and edge welding portions. The intermediate welding portions are disposed between the edge welding portions opposite to each other in the first direction. The second connecting line extends along the second direction, and one end of the second connecting line contacts and connects to the edge welding portions. A fine grid is formed on the first surface, the fine grid extends discontinuously along the first direction, and a plurality of the fine grids are arranged at intervals along the second direction; Wherein, the width of the second connecting line at the end closest to the fine grid is smaller than the width at the other end.

[0019] Optionally, while forming the fine gate on the first surface, a main gate is also formed on the first surface; the main gate extends along the second direction, and a plurality of the main gates are sequentially spaced along the first direction; the other end of the second connecting line is in contact with the fine gate of the same polarity. Optionally, after forming the weld portion and the second connecting line, and before forming the fine grid, a first connecting line is formed on the first surface, the first connecting line extending along the second direction; the first connecting line is disposed on the side of the edge weld portion near the first edge; While forming the fine grid, a short grid is formed on the first surface, the short grid being sandwiched between the edge welding portion and the first edge, and the first connecting line being in contact with the fine grid and the short grid; Wherein, the width of the first connecting line at the end closest to the short gate is smaller than the width at the other end.

[0020] This application also provides a tandem solar cell, comprising: a bottom cell, which is a back-contact photovoltaic cell as described above, or a back-contact photovoltaic cell formed by a method for preparing a plurality of back-contact photovoltaic cells as described above; and a top cell, which is located on one side of the bottom cell.

[0021] This application also provides a photovoltaic module, comprising: a battery string, which is formed by connecting multiple back-contact photovoltaic cells as described above, or formed by connecting multiple back-contact photovoltaic cells formed by the preparation method of the back-contact photovoltaic cells as described above, or formed by connecting multiple stacked cells as described above; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film away from the battery string.

[0022] The technical solution provided in this application has at least the following advantages: The width of the second connecting line at the end closest to the fine grid is smaller than that at the other end. On the one hand, this structure guides the transport of charge carriers, directing them from the fine grid to the edge welding part that is electrically connected to the external circuit. This reduces the connection resistance between the fine grid and the edge welding part, improves the transport efficiency of charge carriers, and thus improves the photoelectric conversion efficiency of the back contact photovoltaic cell. On the other hand, it reduces the amount of paste required to form the second connecting line, thereby reducing the production cost of the back contact photovoltaic cell. Attached Figure Description

[0023] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a back-contact photovoltaic cell provided in one embodiment of this application; Figure 2 for Figure 1 Enlarged structural diagram at point A; Figure 3 This is a step diagram illustrating a method for preparing a back-contact photovoltaic cell according to an embodiment of this application.

[0025] Explanation of reference numerals in the attached figures: 100. Cell body; 1001. First edge; 110. First surface; 111. Main grid area; 112. Fine grid area; 113. Connecting line area; 114. Welding area; 210. Main grid; 211. Middle main grid; 212. Edge main grid; 220. Fine grid; 230. Short grid; 240. First connecting line; 250. Second connecting line; 260. Edge connecting line; 300. Welding part; 310. Middle welding part; 320. Edge welding part. Detailed Implementation

[0026] As is known from the background technology, the grid electrodes and solder joints of BC batteries are located on the back of the battery to completely avoid the grid electrodes being obstructed on the front of the battery. To prevent edge breakage or microcracks caused by the tensile or stress generated by welding with the solder strips, the solder joints on the battery cells are usually designed to be far away from the edge of the battery cell.

[0027] However, the design of the solder joints being far from the edge of the cell, and the presence of two grid lines with different polarities on the back of the BC cell, means that grid lines with different polarities cannot be set between the solder joints with the same polarity at the edge and the main grid. This results in a blank area between the solder joints at the edge and the main grid, which prevents further improvement in the coverage of the grid lines on the cell surface.

[0028] In this embodiment of the back-contact photovoltaic cell, a short grid and a fine grid of the same polarity are connected by a first connecting line. This avoids the short grid being unusable due to being sandwiched between the dissimilar main grid and the welding part, while increasing the coverage of the grid line on the surface of the cell body, thereby improving the collection efficiency of the grid line for charge carriers and thus improving the photoelectric conversion efficiency of the back-contact photovoltaic cell. Since the length of the short grid is smaller than that of the fine grid, the amount of charge carriers collected and transported by the short grid is also less than that by the fine grid. The width of the first connecting line near the fine grid is greater than the width near the short grid. On the one hand, this structure guides the transport of charge carriers, directing them from the shorter short grid to the longer fine grid, reducing the connection resistance between the fine and short grids, improving the transport efficiency of charge carriers, and thus improving the photoelectric conversion efficiency of the back-contact photovoltaic cell. On the other hand, it reduces the amount of paste required to form the first connecting line, thereby reducing the production cost of the back-contact photovoltaic cell.

[0029] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined. Similarly, "multiple sets" refers to two or more sets (including two sets), and "multiple pieces" refers to two or more pieces (including two pieces).

[0030] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0031] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0032] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. For example, if the device or element in the illustration is inverted, then the element described as "below," "under," "below," or "bottom" of other elements or features will be oriented "above" or "top" of said other elements or features. Therefore, the term "below" may cover both above and below orientation depending on the context in which the term is used, which will be obvious to those skilled in the art. Materials may be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0033] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0034] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. Furthermore, when describing a component as "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0035] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. The formation or provision of a second component above or on a first component, or on the surface of a first component, or on one side of a first component, may include embodiments where the first and second components are in direct contact, and may also include embodiments where an additional component may be present between the first and second components, thereby preventing direct contact between the first and second components. For simplicity and clarity, various components may be drawn at different scales. In the drawings, some layers / components may be omitted for simplicity. Unless otherwise specified, the formation or provision of a second component on the surface of a first component refers to direct contact between the first and second components. The term "component" may refer to a layer, film, region, portion, structure, etc.

[0036] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "component" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0037] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0038] Figure 1 A schematic diagram of the structure of a back-contact photovoltaic cell provided in one embodiment of this application is shown.

[0039] refer to Figure 1 Back-contact photovoltaic cells include: The battery cell body 100 has intersecting first direction X, second direction Y and third direction Z; the battery cell body 100 has opposing first surface 110 and second surface in the third direction Z; the first surface 110 has a pair of opposing first edges 1001 in the first direction X; the third direction Z is the thickness direction of the battery cell body 100. Welding portion 300 is disposed on the first surface 110; welding portion 300 includes intermediate welding portion 310 and edge welding portion 320, the intermediate welding portion 310 is disposed between a pair of opposite edge welding portions 320 in the first direction X; Fine grid 220 is disposed on the first surface 110. Fine grid 220 extends intermittently along the first direction X. A plurality of fine grids 220 are arranged at intervals along the second direction Y. A short gate 230 is disposed on the first surface 110, extends along the first direction X, and is disposed between the first edge 1001 and the edge weld portion 320; The first connecting line 240 extends along the second direction Y and is disposed between the first edge 1001 and the edge welding portion 320. The short gate 230 and the adjacent fine gate 220 of the same polarity are electrically connected through the first connecting line 240. In this case, the width of the first connecting line 240 near the short gate 230 is smaller than the width of the other end.

[0040] In this embodiment of the application, the back-contact photovoltaic cell connects the short grid 230 and the fine grid 220 with the same polarity through the first connecting line 240. This avoids the short grid 230 from being unusable due to being sandwiched between the heterogeneous main grid 210 and the welding part 300. At the same time, it increases the coverage of the grid lines on the surface of the cell body 100, thereby improving the collection efficiency of the grid lines for charge carriers and thus improving the photoelectric conversion efficiency of the back-contact photovoltaic cell. Since the length of the short grid 230 is smaller than that of the fine grid 220, the amount of charge carriers collected and transported by the short grid 230 is also less than that of the fine grid 220. The width of the first connecting line 240 near the fine grid 220 is greater than that near the short grid 230. On the one hand, this structure guides the transport of charge carriers, guiding them from the shorter short grid 230 to the longer fine grid 220, reducing the connection resistance between the fine grid 220 and the short grid 230, improving the transport efficiency of charge carriers, and thus improving the photoelectric conversion efficiency of the back contact photovoltaic cell. On the other hand, it reduces the amount of paste required to form the first connecting line 240, thereby reducing the production cost of the back contact photovoltaic cell.

[0041] It should be noted that the intersection of the first direction X and the second direction Y includes the following scenarios: the first direction X and the second direction Y are perpendicular; or, the angle formed by the first direction X and the second direction Y is an obtuse angle; or, the angle formed by the first direction X and the second direction Y is an acute angle. In some examples, the angle between the first direction X and the second direction Y can be 10° to 90°, for example, 10°, 20°, 45°, 55°, 70°, 82°, or 90°. In some specific examples, the angle between the first direction X and the second direction Y can also be 45° to 90°. The scenarios where the first direction X intersects with a third direction Z, and the scenarios where the second direction Y intersects with a third direction Z, can be referred to the corresponding explanations of the scenarios where the first direction X and the second direction Y intersect, and will not be repeated here.

[0042] The embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0043] Reference Figure 1 As shown, the back-contact photovoltaic cell has intersecting and perpendicular first direction X, second direction Y and third direction Z. In this embodiment of the application, the positive electrode and negative electrode of the back-contact photovoltaic cell are both disposed on one side of the back surface of the cell body. The back-contact photovoltaic cell includes a cell body 100, grid lines and welding part 300.

[0044] The solar cell body 100 has a sheet-like structure and exhibits photoelectric effect. The grid lines and welding portions 300 are both disposed on the first surface 110 of the solar cell body 100, which is the backlight surface of the solar cell body 100. In the first direction X, the solar cell body 100 has opposing first edges 1001 on both sides.

[0045] It should be noted that the back-contact photovoltaic cell can be a single-sided cell, and the second surface of the cell body 100 can be considered as the front side of the back-contact photovoltaic cell, serving as the light-receiving surface for receiving incident light, while the first surface 110 is the back-lighting surface. Alternatively, the final back-contact photovoltaic cell can be a bi-sided cell, in which case both sides of the cell body 100 can serve as light-receiving surfaces and can be used to receive incident light. It is understood that the back-lighting surface described in the embodiments of this application can also receive incident light, but the degree of reception of incident light is weaker than that of the light-receiving surface, and therefore it is defined as the back-lighting surface.

[0046] In some embodiments, the battery cell body 100 may be divided into 1 / N whole battery cells, that is, the battery cell body 100 is divided into N pieces, where N is a positive integer greater than 1; in other embodiments, the battery cell body 100 may also be composed of whole battery cells, that is, the battery cell body 100 is a whole piece.

[0047] In some embodiments, the cell body 100 is divided into 1 / 2 whole cells, that is, the cell body 100 is a two-piece (half cell).

[0048] In some embodiments, when the cell body 100 is divided into 1 / N whole cell pieces, the grid lines and welding portions 300 are first formed on the first surface 110 of the whole cell using a screen printing process, and then the whole cell is divided into N segments of the cell body 100 in this embodiment to construct the back contact photovoltaic cell in this embodiment. In other embodiments, the cell body 100 is a single piece, that is, the grid lines and welding portions 300 are formed on the first surface 110 of the cell body 100 using a screen printing process to directly construct the back contact photovoltaic cell in this embodiment.

[0049] Grid lines are disposed on the first surface 110 of the solar cell body 100 to collect and transport photogenerated carriers, thereby realizing the photoelectric conversion of the photovoltaic cell. Since the positive and negative electrodes of the photovoltaic cell in this embodiment are both disposed on the back surface of the solar cell body 100, the polarity of the grid lines can be either positive or negative. The grid lines include a fine grid 220, a main grid 210, a short grid 230, a first connecting line 240, and a second connecting line 250.

[0050] The main gate 210 extends along the second direction Y, and main gates 210 with different polarities are alternately arranged along the first direction X. Fine gates 220 extend intermittently along the first direction X, and several fine gates 220 are alternately arranged along the second direction Y. Fine gates 220 are in contact with main gates 210 of the same polarity, and are disconnected at positions where they differ from the main gates 210 and the weld portion 300, ensuring insulation between the fine gates 220 and the main gates 210 or the weld portion 300, thus preventing short circuits and other problems. The main gate 210 includes a central main gate 211 and edge main gates 212, with the central main gate 211 positioned between a pair of opposing edge main gates 212 along the first direction X.

[0051] The welding part 300 is disposed on the first surface 110 of the cell body 100. The welding part 300 is electrically connected to the main grid 210 or the fine grid 220. The welding part 300 is also welded to the welding strip in the photovoltaic module so as to transmit the charge carriers collected and transmitted by the fine grid 220 and the main grid 210 to the external circuit through the welding strip.

[0052] The welding portion 300 includes a middle welding portion 310 and an edge welding portion 320. The middle welding portion 310 is disposed between the opposing edge welding portions 320 in the first direction X. In other words, the edge welding portions 320 are closer to the first edge 1001 of the cell body 100 in the first direction X than the middle welding portion 310. The middle welding portion 310 is located at the position where the middle main grid 211 and the fine grid 220 intersect and connect. The edge welding portions 320 and the edge main grid 212 are spaced apart in the first direction X, and are electrically connected via an edge connecting line 260. The edge connecting line 260 is a grid line sandwiched between the edge main grid 212 and the edge welding portion 320. The edge connecting line 260 extends along the first direction X, with one end contacting the edge welding portion 320 and the other end contacting the edge main grid 212. The edge connecting line 260 is collinear with a fine grid 220. The edge welding portion 320 and the edge main grid 212 are spaced apart in the first direction X. The distance between the edge welding portion 320 and the first edge 1001 in the first direction X is greater than the distance between the edge main grid 212 and the first edge 1001. This allows the edge welding portion 320 to be far away from the first edge 1001, avoiding the welding stress or the tensile force of the welding strip on the cell body 100 caused by the subsequent welding connection between the edge welding portion 320 and the welding strip to be concentrated on the first edge 1001. This would prevent problems such as fragmentation or microcracks in the cell body 100 at the edge. The spacing between the edge welding portion 320 and the edge main grid 212 improves the yield and reliability of the back contact photovoltaic cell.

[0053] The grid line also includes a short grid 230 and a first connecting line 240. The short grid 230 is disposed between the edge welding portion 320 and the edge main grid 212, and extends along a first direction X. The first connecting line 240 extends along a second direction Y, and passes through the gap of the fine grid 220 with a different polarity to electrically connect the short grid 230 with the adjacent fine grid 220 of the same polarity. To ensure the welding quality of the edge welding portion 320 and its carrier transport efficiency, the edge welding portion 320 is usually large. When the edge welding portion 320 is large in the second direction Y, the fine grid 220 with the opposite polarity will break when it extends to the position of the edge welding portion 320, ensuring the insulation isolation between the fine grid 220 with the opposite polarity and the edge welding portion 320. In related technologies, no grid line structure with a different polarity is typically provided between the edge welding portion 320 and the edge main grid 212. However, this grid-free area prevents the grid line coverage on the surface of the cell body 100 from being further improved, thus hindering the improvement of the photoelectric conversion efficiency of the back-contact photovoltaic cell. In this embodiment, the short grid 230 is provided between the edge welding portion 320 and the edge main grid 212 with a different polarity, further improving the grid line coverage on the surface of the cell body 100, thereby improving the photoelectric conversion efficiency of the back-contact photovoltaic cell.

[0054] In some embodiments, the length of the short grid 230 is 1mm to 2mm. Optionally, the length of the short grid 230 is 1.2mm to 1.8mm, and the length of the short grid 230 can be 1.3mm, 1.4mm, 1.5mm, or 1.6mm. Setting the length of the short grid 230 to 1mm to 2mm ensures, on the one hand, that there is a certain distance between the edge welding part 320 and the edge main grid 212, avoiding the edge welding part 320 being too close to the first edge 1001, which could cause problems such as fragmentation or microcracks at the edge of the cell body 100. On the other hand, it avoids the short grid 230 being too short, resulting in a low capacity for collecting and transporting charge carriers. This would prevent the increased process cost of the first connecting line 240 for connecting the short grid 230 from being unbalanced with the increased light conversion efficiency of the back contact photovoltaic cell due to the short grid 230. This also avoids the short grid 230 and the first connecting line 240 being uncost-effective in terms of production cost.

[0055] Reference Figure 2 As shown, Figure 2 It shows Figure 1The enlarged structural diagram at point A shows a first connecting line 240 extending along the second direction Y. The two ends of the first connecting line 240 are respectively connected to a short gate 230 and a fine gate 220 of the same polarity. The width of the first connecting line 240 gradually increases along its extension direction toward the fine gate 220 it is connected to. In other words, the width of the first connecting line 240 near the fine gate 220 is greater than the width of the other end (i.e., the end of the first connecting line 240 near the short gate 230 it is connected to). This gradual width design of the first connecting line 240 reduces the connection resistance between the fine gate 220 and the short gate 230, improving the carrier transport efficiency and thus increasing the photoelectric conversion efficiency of the back contact photovoltaic cell. Furthermore, it reduces the amount of paste required to form the first connecting line 240, thereby lowering the production cost of the back contact photovoltaic cell.

[0056] In some embodiments, the ratio between the width of the first connecting line 240 near the end of the fine gate 220 that it contacts and the width of the other end (i.e., the end of the first connecting line 240 near the short gate 230 that it contacts and the other end) is 1 to 1.5. Optionally, the ratio between the width of the first connecting line 240 near the end of the fine gate 220 that it contacts and the width of the other end (i.e., the end of the first connecting line 240 near the short gate 230 that it contacts and the other end) is 1.05 to 1.45, and the ratio between the width of the first connecting line 240 near the end of the fine gate 220 that it contacts and the other end (i.e., the end of the first connecting line 240 near the short gate 230 that it contacts and the other end) can be 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, or 1.4.

[0057] In some embodiments, the width of the end of the first connecting line 240 near the fine gate 220 in contact with it is 8 μm to 20 μm. Optionally, the width of the end of the first connecting line 240 near the fine gate 220 in contact with it is 10 μm to 18 μm, and the width of the end of the first connecting line 240 near the fine gate 220 in contact with it can be 12 μm, 14 μm, 15 μm or 16 μm.

[0058] In some embodiments, the width of the end of the first connecting line 240 near the short gate 230 in contact with it is 8 μm to 15 μm. Optionally, the width of the end of the first connecting line 240 near the short gate 230 in contact with it is 9 μm to 14 μm, and the width of the end of the first connecting line 240 near the short gate 230 in contact with it can be 10 μm, 11 μm, 12 μm or 13 μm.

[0059] Furthermore, the first connecting line 240 is in cross contact with the short gate 230 and / or the fine gate 220 to which it is in contact. In other words, the end of the first connecting line 240 that connects to the short gate 230 or the fine gate 220 protrudes at least partially from the short gate 230 or the fine gate 220 in the second direction Y, that is, the first connecting line 240 extends to the side of the fine gate 220 to which it is in contact, away from the side of the short gate 230, and / or, the first connecting line 240 extends to the side of the short gate 230 to which it is in contact, away from the side of the fine gate 220 to which it is in contact. In other words, in the second direction Y, the distance between the end of the first connecting line 240 near one of the short gate 230 or the fine gate 220 and the other of the short gate 230 or the fine gate 220 is greater than the distance between the short gate 230 and the fine gate 220. In yet another way, in the second direction Y, the length of the first connecting line 240 is greater than the distance between the short gate 230 and the fine gate 220. The design of the first connecting line 240 extending to the other side of the fine grid 220 or the short grid 230 serves two purposes. First, it avoids the first connecting line 240 from not overlapping with the fine grid 220 or the short grid 230 due to printing misalignment during the printing process, which could lead to the failure of the short grid 230 and a reduction in the photoelectric conversion efficiency of the back-contact photovoltaic cell. Second, it improves the overlap effect between the first connecting line 240 and the fine grid 220 or the short grid 230, reduces the connection resistance between them, and improves the carrier transport capability.

[0060] In some embodiments, the length of the portion of the first connection line 240 extending to the other side of the fine gate 220 or the short gate 230 is 50 μm to 130 μm. Optionally, the length of the portion of the first connection line 240 extending to the other side of the fine gate 220 or the short gate 230 is 60 μm to 120 μm, and the length of the portion of the first connection line 240 extending to the other side of the fine gate 220 or the short gate 230 can be 70 μm, 80 μm, 90 μm or 100 μm.

[0061] Furthermore, the first connecting line 240 and the fine gate 220 or short gate 230 that are in contact with it have a separate structure, that is, the first connecting line 240 and the fine gate 220 or short gate 230 that are in contact with it are formed asynchronously. Furthermore, the first connecting line 240 and the main gate 210 are made of the same material, and the first connecting line 240 and the main gate 210 are formed synchronously during the fabrication process.

[0062] It should be noted that the printing direction is typically determined based on the larger structure during the printing process. For example, during the simultaneous printing of the first connecting line 240 and the main grid 210, the printing direction is typically along the extension direction of the main grid 210 (i.e., the second direction Y). Similarly, during the simultaneous printing of the first connecting line 240 and the fine grid 220, the printing direction is typically along the extension direction of the fine grid 220 (i.e., the first direction X). However, an intersection of the printing direction and the grid line extension direction carries the risk of incomplete printing or short grid lines. The first connecting line 240 extends in the same direction as the main grid 210. The first connecting line 240 is formed synchronously with the main grid 210 during the manufacturing process, ensuring that the printed shape of the first connecting line 240 is complete and continuous during the printing process. This avoids the situation where the first connecting line 240 is not fully printed during the synchronous printing of the fine grid 220 or short grid 230 that intersects with its extension direction, resulting in incomplete printing and failure to overlap with the fine grid 220 or short grid 230, or grid breakage. This improves the production yield of the back contact photovoltaic cell in the embodiment of this application.

[0063] Combination Figure 1 , Figure 2 As shown, the grid line also includes a second connecting line 250, which is disposed between the edge welding portion 320 and the adjacent fine grid 220 of the same polarity. The second connecting line 250 electrically connects the edge welding portion 320 and the fine grid 220. The second connecting line 250 extends along the second direction Y, with one end of the second connecting line 250 in contact with the edge welding portion 320 and the other end in contact with the fine grid 220. The design of the first connecting line 240 causes a fine gate 220 adjacent to the first welding part 300 to be disconnected at the location of the first connecting line 240. This means that this part of the fine gate 220 cannot be directly electrically connected to the edge main gate 212. The second connecting line 250 electrically connects this part of the fine gate 220 to the edge welding part 320. On the one hand, this ensures that the charge carriers collected by this part of the fine gate 220 can be transmitted to the edge welding part 320 through the second connecting line 250. On the other hand, this part of the fine gate 220 is directly electrically connected to the edge welding part 320 through the second connecting line 250, without having to go through other gate structures such as the edge main gate 212. This shortens the transport path of the charge carriers, reduces the internal resistance, and improves the transport efficiency of the charge carriers, thereby improving the photoelectric conversion efficiency of the back contact photovoltaic cell.

[0064] Furthermore, the width of the second connecting line 250 gradually increases along its extension direction toward the edge welding portion 320 with which it contacts. In other words, the width of the second connecting line 250 near the edge welding portion 320 is greater than the width of the other end (i.e., the end of the second connecting line 250 near the fine grid 220 with which it contacts). This gradual width design of the second connecting line 250 serves two purposes: firstly, it guides the transport of charge carriers, directing them from the fine grid 220 to the edge welding portion 320 which is electrically connected to the external circuit, reducing the connection resistance between the fine grid 220 and the edge welding portion 320, improving the transport efficiency of charge carriers, and thus improving the photoelectric conversion efficiency of the back contact photovoltaic cell; secondly, it reduces the amount of paste required to form the second connecting line 250, thereby reducing the production cost of the back contact photovoltaic cell.

[0065] In some embodiments, the ratio between the width of the second connecting line 250 near the edge weld portion 320 that contacts it and the width of the other end of the second connecting line 250 (the end of the second connecting line 250 that contacts the fine gate 220 that contacts it) is 1 to 1.5. Optionally, the ratio between the width of the second connecting line 250 near the edge weld portion 320 that contacts it and the width of the other end of the second connecting line 250 (the end of the second connecting line 250 that contacts the fine gate 220 that contacts it) is 1.05 to 1.45, and the ratio between the width of the second connecting line 250 near the edge weld portion 320 that contacts it and the width of the other end of the second connecting line 250 (the end of the second connecting line 250 that contacts the fine gate 220 that contacts it) can be 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, or 1.4.

[0066] In some embodiments, the width of the end of the second connecting line 250 near the edge welding portion 320 in contact with it is 8μm to 20μm. Optionally, the width of the end of the second connecting line 250 near the edge welding portion 320 in contact with it is 10μm to 18μm, and the width of the end of the second connecting line 250 near the edge welding portion 320 in contact with it can be 12μm, 14μm, 15μm or 16μm.

[0067] In some embodiments, the width of the second connecting line 250 near the end of the fine gate 220 in contact with it is 8 μm to 15 μm. Optionally, the width of the second connecting line 250 near the end of the fine gate 220 in contact with it is 9 μm to 14 μm, and the width of the second connecting line 250 near the end of the fine gate 220 in contact with it can be 10 μm, 11 μm, 12 μm or 13 μm.

[0068] Furthermore, the second connecting line 250 is in cross contact with the fine gate 220 to which it is in contact. In other words, the end of the second connecting line 250 that connects to the fine gate 220 at least partially protrudes from the fine gate 220 in the second direction Y, that is, the second connecting line 250 extends to the side of the fine gate 220 to which it is in contact, away from the edge weld portion 320 to which it is connected. In other words, in the second direction Y, the distance between the end of the second connecting line 250 near the fine gate 220 and the edge weld portion 320 is greater than the distance between the edge weld portion 320 and the fine gate 220. In yet another way, in the second direction Y, the length of the second connecting line 250 is greater than the distance between the edge weld portion 320 and the fine gate 220. The design of extending the second connecting line 250 to the other side of the fine grid 220 serves two purposes. First, it avoids the second connecting line 250 from not overlapping with the fine grid 220 due to printing offset during the printing process, which would lead to the failure of the fine grid 220 and a reduction in the photoelectric conversion efficiency of the back-contact photovoltaic cell. Second, it improves the overlap effect between the first connecting line 240 and the fine grid 220, reduces the connection resistance between the two, and improves the carrier transport capability.

[0069] In some embodiments, the length of a portion of the second connection line 250 extending to the other side of the fine gate 220 is 50 μm to 130 μm. Optionally, the length of a portion of the second connection line 250 extending to the other side of the fine gate 220 is 60 μm to 120 μm, and the length of a portion of the second connection line 250 extending to the other side of the fine gate 220 can be 70 μm, 80 μm, 90 μm, or 100 μm.

[0070] Furthermore, the second connecting line 250 and the edge welding part 320 are an integral structure, that is, the second connecting line 250 and the edge welding part 320 are formed simultaneously during the manufacturing process.

[0071] It should be noted that the height of the welding portion 300 on the surface of the cell body 100 is usually higher than the height of the grid line on the surface of the cell body 100. This is to reduce the connection resistance between the welding portion 300 and the solder strip, and to ensure the welding connection between the welding portion 300 and the solder strip, avoiding problems such as desoldering. In related technologies, the grid line and the welding portion 300 are usually printed in separate steps. For example, if the second connecting line 250 in this embodiment is printed after the welding portion 300, to ensure the connection between the two, a portion of the second connecting line 250 will be stacked on the surface of the edge welding portion 320, that is, the portion of the second connecting line 250 stacked on the edge welding portion 320 will protrude from the surface of the edge welding portion 320. The edge welding portion 320 is welded to the solder strip, and the solder strip will be stacked on this portion of the second connecting line 250. The pressure applied by the solder strip to the second connecting line 250 and the thermal stress generated during the solder strip welding connection can both cause the second connecting line 250 to have grid breakage. In this embodiment, the second connecting line 250 and the edge welding portion 320 are an integral structure, formed simultaneously during the manufacturing process. The surfaces of the second connecting line 250 and the edge welding portion 320 are flush, avoiding the situation where part of the second connecting line 250 and the edge welding portion 320 overlap, thereby avoiding the problem of grid breakage caused by the second connecting line 250 being squeezed by the welding strip or welding thermal stress, and improving the reliability of the back contact photovoltaic cell in this embodiment.

[0072] Continue to refer to Figure 2 As shown, the first surface 110 includes a main gate region 111 and a fine gate region 112. The main gate region 111 extends along the second direction Y, and main gate regions 111 with different polarities are alternately arranged along the first direction X. A main gate 210 is correspondingly arranged within the main gate region 111 with the same polarity. The fine gate region 112 extends discontinuously along the first direction X, and fine gate regions 112 with different polarities are alternately arranged along the second direction Y. A fine gate 220 is correspondingly arranged within the fine gate region 112 with the same polarity. The fine gate region 112 is interrupted at the location of the main gate region 111.

[0073] The first surface 110 also includes a connecting line region 113, which is correspondingly disposed with the first connecting line 240. The connecting line region 113 extends along the second direction Y and is connected to the fine gate region 112 with the same polarity and adjacent to it. The fine gate region 112 is disconnected at the location of the connecting line with a different polarity.

[0074] In some embodiments, the ratio between the width of the connecting line region 113 and the length of the short grid 230 in the first direction X is 0.5 to 1. Optionally, the ratio between the width of the connecting line region 113 and the length of the short grid 230 in the first direction X is 0.55 to 0.95, and the ratio can be 0.6, 0.7, 0.8, or 0.9. It should be noted that an isolation region (not shown in the figure) is provided between adjacent regions with different polarities, which insulate and isolate regions with different polarities in the cell body 100. If the width of the connecting line region 113 in the first direction X is too small, the isolation regions on both sides of the connecting line region 113 may not be fully formed due to process errors, which may lead to a risk of short-circuit current between the connecting line region 113 and the adjacent fine grid region 112 with different polarities. In this embodiment, the ratio between the width of the connecting line region 113 and the length of the short grid 230 is set to 0.5~1. On the one hand, this avoids short-circuit current between the connecting line region 113 and the adjacent fine grid region 112 with different polarities, thereby improving the open-circuit voltage and fill factor of the back contact photovoltaic cell in this embodiment. On the other hand, it ensures that the first connecting line 240 disposed in the connecting line region 113 is insulated from its adjacent main grid 210 or fine grid 220 with different polarities.

[0075] The first surface 110 also includes a welding region 114 corresponding to the welding portion 300. The welding portion 300 is disposed within the welding region 114, which has the same polarity. The welding region 114 is connected to the fine gate region 112, which has the same polarity, in the second direction Y. A second connecting line 250 is disposed within either the welding region 114 or the fine gate region 112, which has the same polarity. That is, the second connecting line 250 at least partially passes through the welding region 114 and the fine gate region 112 to connect the edge welding portion 320 and the fine gate 220.

[0076] Accordingly, another embodiment of this application also provides a method for preparing a back-contact photovoltaic cell, which can be used to manufacture the back-contact photovoltaic cell provided in the above embodiments. The preparation method of the back-contact photovoltaic cell provided in another embodiment of this application will be described in detail below with reference to the accompanying drawings. For parts that are the same as or corresponding to the previous embodiment, please refer to the corresponding descriptions of the foregoing embodiments; detailed descriptions will not be repeated below.

[0077] Reference Figure 3 As shown, Figure 3 The diagram illustrates the steps of a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application. The method for fabricating a back-contact photovoltaic cell includes: Step S10: Provide a battery cell body 100, which has a first surface 110 and a second surface opposite each other in the third direction Z; the battery cell body 100 has a first edge 1001 opposite each other in the first direction X; the first direction X, the second direction Y and the third direction Z intersect, and the third direction Z is the thickness direction of the battery cell body 100.

[0078] In step S20, a plurality of weld portions 300 are formed on the first surface 110. Each weld portion 300 includes an intermediate weld portion 310 and an edge weld portion 320. The intermediate weld portion 310 is disposed between the opposite edge weld portions 320 in the first direction X.

[0079] In step S30, a first connecting line 240 is formed on the first surface 110, and the first connecting line 240 extends along the second direction Y. The first connecting line 240 is disposed on the side of the edge welding portion 320 near the first edge 1001.

[0080] In step S40, short grids 230 and fine grids 220 are formed on the first surface 110. The fine grids 220 extend along the first direction X, and a plurality of fine grids 220 are arranged at intervals along the second direction Y. The short grids 230 are sandwiched between the edge welding portion 320 and the first edge 1001. The first connecting line 240 contacts and connects with the fine grids 220 and the short grids 230. The width of the first connecting line 240 near the short grids 230 is smaller than the width of the other end.

[0081] The back-contact photovoltaic cell fabrication method in this embodiment connects the short grid 230 and the fine grid 220 with the same polarity via the first connecting line 240. This avoids the short grid 230 being unusable due to being sandwiched between the heterogeneous main grid 210 and the welding part 300. At the same time, it increases the coverage of the grid lines on the surface of the cell body 100, thereby improving the collection efficiency of the grid lines for charge carriers and improving the photoelectric conversion efficiency of the back-contact photovoltaic cell. Since the length of the short grid 230 is smaller than that of the fine grid 220, the amount of charge carriers collected and transported by the short grid 230 is also less than that of the fine grid 220. The width of the first connecting line 240 near the fine grid 220 is greater than that near the short grid 230. On the one hand, this structure guides the transport of charge carriers, guiding them from the shorter short grid 230 to the longer fine grid 220, reducing the connection resistance between the fine grid 220 and the short grid 230, improving the transport efficiency of charge carriers, and thus improving the photoelectric conversion efficiency of the back contact photovoltaic cell. On the other hand, it reduces the amount of paste required to form the first connecting line 240, thereby reducing the production cost of the back contact photovoltaic cell.

[0082] Furthermore, during the formation of the first connecting line 240, a main gate 210 is formed on the first surface 110. The main gate 210 extends along the second direction Y, and several main gates 210 are sequentially spaced along the first direction X. A fine gate 220 contacts and connects with the main gate 210 and / or the weld portion 300 of the same polarity, and the fine gate 220 is disconnected at positions of the main gate 210 and / or the weld portion 300 with different polarities. The first connecting line 240 is formed synchronously with the main gate 210.

[0083] It should be noted that the first connecting line 240 extends in the same direction as the main grid 210. The first connecting line 240 is formed synchronously with the main grid 210 during the manufacturing process, ensuring that the printed shape of the first connecting line 240 is complete and continuous during the printing process. This avoids the situation where the first connecting line 240 does not overlap with the fine grid 220 or short grid 230 or the grid is broken due to incomplete printing during the synchronous printing of the fine grid 220 or short grid 230 that intersects with its extension direction. This improves the production yield of the back contact photovoltaic cell in the embodiment of this application.

[0084] Furthermore, the welding portion 300 includes an intermediate welding portion 310 and an edge welding portion 320, with the intermediate welding portion 310 disposed between opposing edge welding portions 320 in the first direction X. During the formation of the welding portion 300, a second connecting line 250 is formed on the first surface 110. The second connecting line 250 extends along the second direction Y and is disposed between the edge welding portion 320 and adjacent fine grids 220 of the same polarity. The second connecting line 250 electrically connects the edge welding portion 320 and the fine grids 220. The second connecting line 250 is formed synchronously with the welding portion 300, that is, the second connecting line 250 is formed synchronously with the edge welding portion 320.

[0085] It should be noted that the second connecting line 250 and the welding part 300 are formed simultaneously during the manufacturing process. The surfaces of the second connecting line 250 and the edge welding part 320 are flush, which avoids the situation where part of the second connecting line 250 and the edge welding part 320 overlap. This avoids the problem of grid breakage caused by the second connecting line 250 being squeezed by the welding strip or by welding thermal stress, and improves the reliability of the back contact photovoltaic cell in this embodiment.

[0086] In some embodiments, the width of the second connection line 250 gradually increases in its extension direction toward the edge weld portion 320 with which it contacts. The gradient design of the width of the second connection line 250 reduces the connection resistance between the fine grid 220 and the edge weld portion 320, improves the carrier transport efficiency, and on the other hand reduces the amount of paste required to form the second connection line 250, thereby reducing the production cost of the back contact photovoltaic cell.

[0087] In some embodiments, the paste forming the first connection line 240 is a non-burn-through paste to avoid printing misalignment of the first connection line 240 during the printing process, which would cause electrical connection between the first connection line 240 and the doped layer with different polarity, thereby resulting in short-circuit current and a decrease in the photoelectric conversion efficiency of the back contact photovoltaic cell.

[0088] In some embodiments, the slurry forming the second connection line 250 is a non-burn-through slurry.

[0089] Accordingly, another embodiment of this application also provides a stacked battery, which includes a back-contact photovoltaic cell and a thin-film battery stacked on one side of the back-contact photovoltaic cell. The back-contact photovoltaic cell serves as the bottom cell in the stacked battery, and the thin-film battery serves as the top cell in the stacked battery. The back-contact photovoltaic cell is the back-contact photovoltaic cell provided in the above embodiment. The stacked battery provided in the second embodiment of this application will be described in detail below. For parts that are the same as or corresponding to the previous embodiment, please refer to the corresponding descriptions of the foregoing embodiments, which will not be repeated in detail below.

[0090] In some embodiments, the thin-film battery includes at least one of a perovskite thin-film battery, a gallium arsenide thin-film battery, a cadmium telluride thin-film battery, and a copper indium gallium selenide thin-film battery.

[0091] Accordingly, another embodiment of this application also provides a photovoltaic module, which includes a cell string, an encapsulating film, and a cover plate. The cell string is formed by connecting a plurality of back-contact photovoltaic cells or stacked cells, wherein the back-contact photovoltaic cells are as described in the above embodiments or are prepared by the same method as described in the above embodiments, and the stacked cells are as described in the above embodiments; the encapsulating film covers the surface of the back-contact photovoltaic cells; the cover plate is located on the surface of the encapsulating film away from the back-contact photovoltaic cells. For parts that are the same as or corresponding to the previous embodiment, please refer to the corresponding descriptions of the foregoing embodiments, which will not be elaborated upon below.

[0092] The encapsulating film can be made of ethylene. Organic encapsulation films such as vinyl acetate copolymer films, polyvinyl octene co-elastomer films, or polyvinyl butyral films.

[0093] The cover plate can be a glass cover plate, a plastic cover plate, or other cover plate with light transmission function. In some embodiments, the surface of the cover plate facing the adhesive film can be an uneven surface, thereby increasing the utilization rate of incident light.

[0094] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A back contact photovoltaic cell, characterized by, The back contact photovoltaic cell comprises: a cell body having a first direction, a second direction and a third direction intersecting with each other; the cell body has opposite first and second surfaces in the third direction; the third direction is the thickness direction of the cell body; a welding portion provided on the first surface; the welding portion comprises an intermediate welding portion and edge welding portions opposite to each other in the first direction; a fine grid provided on the first surface, the fine grid extending discontinuously along the first direction, and a plurality of the fine grids being arranged in sequence and spaced apart along the second direction; a second connecting line provided on the first surface, the second connecting line extending along the second direction, and the edge welding portion and the fine grid of the same polarity being electrically connected through the second connecting line; wherein the width of one end of the second connecting line close to the fine grid is smaller than the width of the other end.

2. The back contact photovoltaic cell of claim 1, wherein, The back contact photovoltaic cell further comprises: a main grid provided on the first surface, the main grid extending along the second direction, and a plurality of the main grids being arranged in sequence and spaced apart along the first direction; the main grid comprises an intermediate main grid and edge main grids opposite to each other in the first direction; the corresponding edge main grid and edge welding portion are arranged in a staggered manner in the first direction.

3. The back contact photovoltaic cell of claim 1, wherein, The width of one end of the second connecting line close to the fine grid is 8-15 μm, and the width of one end of the second connecting line close to the edge welding portion is 8-20 μm.

4. The back contact photovoltaic cell of claim 1, wherein, The second connecting line is cross-connected with the fine grid in contact therewith, and at least part of the second connecting line extends to the other side of the fine grid away from the edge welding portion.

5. The back contact photovoltaic cell of claim 4, wherein, The length of the part of the second connecting line extending to the other side of the fine grid is 50-130 μm.

6. The back contact photovoltaic cell of claim 1, wherein, The ratio between the width of one end of the second connecting line close to the edge welding portion in contact therewith and the width of the other end of the second connecting line is 1-1.

5.

7. The back contact photovoltaic cell of claim 2, wherein, The first surface has opposite first edges in the first direction. The back contact photovoltaic cell further comprises: a short grid provided on the first surface, the short grid extending along the first direction, and the short grid being arranged between the first edge and the edge welding portion; a first connecting line extending along the second direction, the first connecting line being arranged between the first edge and the edge welding portion, and the short grid and the fine grid of the same polarity adjacent thereto being electrically connected through the first connecting line; wherein the width of one end of the first connecting line close to the short grid is smaller than the width of the other end.

8. The back contact photovoltaic cell of claim 7, wherein, The width of the first connecting line in the first direction gradually increases in the direction away from the short grid in contact therewith.

9. The back contact photovoltaic cell of claim 7, wherein, The ratio between the width of one end of the first connecting line close to the fine grid in contact therewith and the width of the other end of the first connecting line is 1-1.

5.

10. The back contact photovoltaic cell of claim 9, wherein, The width of the first connecting line near the end of the thin grid in contact therewith is 8-20 μm, and the width of the first connecting line near the end of the short grid in contact therewith is 8-15 μm.

11. The back contact photovoltaic cell of claim 7, wherein, The first connecting line is in contact with the thin grid and / or the short grid, and at least part of the first connecting line extends to the side of the thin grid away from the short grid, and / or at least part of the first connecting line extends to the side of the short grid away from the thin grid.

12. The back contact photovoltaic cell of claim 11, wherein, The length of the part of the first connecting line extending to the other side of the thin grid or the short grid is 50-130 μm.

13. The back contact photovoltaic cell of claim 7, wherein, The material of the first connecting line is the same as that of the main grid, and the first connecting line is in a separate structure with the thin grid and / or the short grid. The second connecting line is in contact with the edge soldering part in an integral structure.

14. A method of fabricating a back contact photovoltaic cell, characterized by, The method comprises the following steps: A battery piece body is provided, which has opposite first and second surfaces in a third direction; the battery piece body has opposite first edges in a first direction; the first, second and third directions intersect, and the third direction is the thickness direction of the battery piece body; A plurality of soldering parts and second connecting lines are formed on the first surface; the soldering parts include intermediate soldering parts and edge soldering parts, and the intermediate soldering parts are arranged between the edge soldering parts opposite in the first direction; the second connecting lines extend along the second direction, and one end of the second connecting line is in contact with the edge soldering part; A thin grid is formed on the first surface, and the thin grid extends discontinuously along the first direction; a plurality of thin grids are arranged in sequence along the second direction; The width of one end of the second connecting line near the thin grid is smaller than that of the other end.

15. The method of claim 14, wherein the back contact photovoltaic cell is prepared by a process comprising: The main grid is formed on the first surface at the same time as the thin grid; the main grid extends along the second direction, and a plurality of main grids are arranged in sequence along the first direction; the other end of the second connecting line is in contact with the thin grid of the same polarity.

16. The method of claim 14, wherein the back contact photovoltaic cell is prepared by a process comprising: After the step of forming the soldering parts and the second connecting lines, and before the step of forming the thin grid, a first connecting line is formed on the first surface; the first connecting line extends along the second direction; the first connecting line is arranged on the side of the edge soldering part near the first edge; A short grid is formed on the first surface at the same time as the thin grid; the short grid is arranged between the edge soldering part and the first edge, and the first connecting line is in contact with the thin grid and the short grid; The width of one end of the first connecting line near the short grid is smaller than that of the other end.

17. A stacked battery characterized by comprising: The method comprises the following steps: A bottom cell is a back contact photovoltaic cell as claimed in any one of claims 1-13, or a back contact photovoltaic cell formed by the preparation method of a plurality of back contact photovoltaic cells as claimed in any one of claims 14-16; A top cell is located on one side of the bottom cell.

18. A photovoltaic module, characterized by, The method comprises the following steps: a battery string connected by a plurality of back contact photovoltaic cells as claimed in any one of claims 1 to 13, or formed by a manufacturing method of a back contact photovoltaic cell as claimed in any one of claims 14 to 16, or connected by a plurality of laminated cells as claimed in claim 17; an encapsulant film for covering a surface of the battery string; a cover plate for covering a surface of the encapsulant film away from the battery string.

Images