Back contact photovoltaic cells and photovoltaic modules

Abstract

The present application relates to the field of photovoltaic cells and provides a back-contact photovoltaic cell and photovoltaic module. The back-contact photovoltaic cell comprises: a cell body, comprising a central region and edge regions on both sides thereof; fine grids, comprising current collecting grids and bus grids; the current collecting grids are disposed in the central region and extend continuously along a first direction; the bus grids are disposed in the edge regions and extend intermittently along the first direction; connecting wires, disposed in the edge regions; the connecting wires comprise middle connecting wires and side connecting wires; a pair of side connecting wires are disposed at the edges of the cell body, with the middle connecting wire sandwiched between the pair of side connecting wires; and welding structures, wherein a plurality of welding structures are electrically connected to the current collecting grids or connecting wires; wherein the width of the middle connecting wires is greater than the width of the side connecting wires. Embodiments of the present application can at least address the problem of low carrier transmission efficiency along the path where the main grid is connected to the fine grids.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic cells, and in particular to a back-contact photovoltaic cell and a photovoltaic module. Background Art

[0002] In solar photovoltaic technology, the most notable feature of interdigitated back contact (IBC) cells is that the PN junction and contact metal are both located on the back of the IBC cell. The front of the IBC cell completely avoids the obstruction of the metal grid electrode, can maximize the use of incident light, reduce optical losses, and have a higher short-circuit current.

[0003] In related technologies, back-contact cells typically use a main grid to connect fine grids of the same polarity, and then solder the main grid to the solder ribbon using pads on the main grid. However, carriers on the fine grids not connected to the pads must first be transferred to the main grid and then transferred to the solder ribbon via the pads. This transmission path is long and results in low carrier transfer efficiency.

[0004] Therefore, how to design a back-contact photovoltaic cell with high transmission efficiency is a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] The embodiments of the present application provide a back-contact photovoltaic cell and photovoltaic module, which at least helps to solve the problem of low carrier transmission efficiency in the path of connecting the main grid to the fine grid.

[0006] According to some embodiments of the present disclosure, the present application provides a back-contact photovoltaic cell, the back-contact photovoltaic cell comprising:

[0007] a battery body, the battery body having a first direction and a second direction intersecting and perpendicular to each other, the battery body comprising a central region and edge regions located on both sides of the central region with respect to the first direction;

[0008] A gate line structure, wherein the fine gates include a current collecting fine gate and a bus fine gate; the current collecting fine gate and the bus fine gate extend along the first direction, and a plurality of the current collecting fine gates and the bus fine gate are sequentially arranged along the second direction; the current collecting fine gate is arranged in the central area and extends continuously along the first direction; the bus fine gate is arranged in the edge area and extends intermittently along the first direction;

[0009] connecting wires, the connecting wires being arranged in the edge region and electrically connected to bus bars of the same polarity; the connecting wires comprising a middle connecting wire and side connecting wires, the middle connecting wires and side connecting wires extending along the second direction; a pair of the side connecting wires being arranged at both side edges of the battery body with respect to the second direction, the middle connecting wire being sandwiched between the pair of the side connecting wires;

[0010] Welding structures, some of which are electrically connected to the current collecting grids or the connecting wires;

[0011] Wherein, in the first direction, the width of the middle connecting line is greater than the width of the side connecting line.

[0012] In some embodiments, in the first direction, the width of the middle connecting line is a first width W1, and the width of the side connecting line is a second width W2; in the second direction, the width of the current collecting grid and the bus bar is a third width W3; wherein, W1>W2>W3, 400μm≥W1≥250μm, 250μm≥W2≥50μm.

[0013] In some embodiments, the welded structure comprises:

[0014] a first welding portion, the first welding portion being arranged on a side of the edge region close to the central region, the first welding portion being electrically connected to a connection line having the same polarity as the first welding portion;

[0015] A second welding portion is provided in the central region, and the second welding portion is electrically connected to the current collecting grid.

[0016] In some embodiments, adjacent bus bars extending along the same straight line have gaps between them.

[0017] The first welding portion is electrically connected to the bus bar with the same polarity as the bus bar that is closest to the center area in the edge area. After the first welding portion passes through the gap between the adjacent bus bar with different polarities in the second direction, the first welding portion is electrically connected to another bus bar or the current collecting bar with the same polarity.

[0018] In some embodiments, the first welding portion includes a middle welding portion and a side welding portion, the middle welding portion is electrically connected to the middle connecting line, and the side welding portion is electrically connected to the side connecting line;

[0019] The connecting line also includes an extension connecting line;

[0020] The distance between the side welding portion and the corresponding first edge is greater than the distance between the side connection line electrically connected to the side welding portion and the first edge, and the side welding portion is electrically connected to the side connection line through the extended connection line extending along the first direction.

[0021] In some embodiments, in the second direction, the length of the side welding portion is a fourth length L4, and the spacing dimension between adjacent bus bars or current collecting bars is a spacing length g, wherein 4g>L4>2g.

[0022] In some embodiments, in the second direction, the length of the middle welding portion is a third length L3, and the length of the side welding portion is a fourth length L4, wherein L4>L3.

[0023] In some embodiments, the busbar includes a break grid provided on a side of the side welding portion facing the corresponding edge of the battery body;

[0024] The grid line structure also includes: an extended connecting fine grid, which extends along the second direction, and is arranged on the side of the side welding portion facing the corresponding edge of the battery body, and the two ends of the extended connecting fine grid are respectively electrically connected to the broken grid and the busbar grid with the same polarity.

[0025] In some embodiments, the two end edges of the battery body extending along the first direction are first edges, and the two end edges of the battery body extending along the second direction are second edges;

[0026] wherein the distance between one end of the connecting line in the second direction and the corresponding second edge is smaller than the distance between any bus bar electrically connected to the connecting line and the second edge;

[0027] A distance between one end of a bus bar electrically connected to the side connection line and a first edge corresponding to the end of the bus bar in the first direction is smaller than a distance between the side connection line and the first edge.

[0028] In some embodiments, an auxiliary connection line is further included, which passes through the central area along the second direction and is electrically connected to the side connection lines on both sides; the auxiliary connection line is electrically connected to the current collecting fine grid with the same polarity.

[0029] In some embodiments, the two end edges of the battery body extending along the first direction are first edges, and the two end edges of the battery body extending along the second direction are second edges;

[0030] The distance between one end of the current collecting gate 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.

[0031] In some embodiments, in the first direction, the width of the side connection line is a second width W2, and the width of the auxiliary connection line is a fifth width W5, wherein W2>W5, 250μm≥W2≥50μm, and 200μm≥W5≥30μm.

[0032] According to some embodiments of the present disclosure, another aspect of the present application further provides a photovoltaic module, wherein the photovoltaic module includes a cell string, wherein the cell string is composed of a plurality of back-contact photovoltaic cells connected together, and the back-contact photovoltaic cell is any one of the back-contact photovoltaic cells described above;

[0033] a welding ribbon connecting adjacent back-contact photovoltaic cells;

[0034] an encapsulation film, the encapsulation film covering the surface of the back-contact photovoltaic cell;

[0035] A cover plate is located on a surface of the packaging film away from the back contact photovoltaic cell.

[0036] The technical solution provided by the embodiments of the present application has at least the following advantages: By configuring the grid lines in the central region of the battery body as current collecting grids and the grid lines in the edge regions as collector grids, the collector grids are directly electrically connected to the welding structure, shortening the transmission path of carriers collected by the collector grids to the welding structure, thereby improving carrier transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 A schematic structural diagram of a back-contact photovoltaic cell provided according to an embodiment of the present application;

[0039] Figure 2 A schematic structural diagram of a back-contact photovoltaic cell provided according to another embodiment of the present application.

[0040] In the figure: 100, battery body; 101, first edge; 102, second edge; 110, central area; 120, edge area; 200, grid line structure; 210, current collecting grid; 220, current collecting grid; 2201, gap; 221, broken grid; 230, extended connecting grid; 300, connecting line; 310, middle connecting line; 320, side connecting line; 330, extended connecting line; 340, auxiliary connecting line; 400, welding structure; 410, first welding part; 411, middle welding part; 412, side welding part; 420, second welding part. DETAILED DESCRIPTION

[0041] As can be seen from the background art, in related art, a busbar is typically installed to connect grid lines of the same polarity, and then the busbar is welded to the soldering ribbon using the soldering structure on the busbar to reduce the number of soldering structures. However, in this structure, the carriers on the grid lines that are not connected to the soldering structure need to be transferred to the busbar first, and then transferred to the soldering ribbon through the soldering structure. The carrier transfer efficiency on this path is low, thus affecting the photoelectric conversion efficiency of the back-contact photovoltaic cell. In addition, the installation of the busbar will increase the cost of the slurry.

[0042] The present disclosure provides a back-contact photovoltaic cell, which is configured by setting the grid line structure in the central area of ​​the cell body as a current collecting grid and the grid line structure in the edge area as a busbar grid. The current collecting grid is directly electrically connected to the welding structure, and the transmission path of the carriers collected by the current collecting grid to the welding structure is shorter, thereby improving the transmission efficiency of the carriers. The busbar grids of the same polarity are electrically connected to the welding structure through connecting wires, and the width of the middle connecting wire connecting more busbar grids is greater than the width of the side connecting wires provided on both sides and connecting fewer busbar grids. The internal resistance of the middle connecting wire with a larger width is smaller, thereby improving the transmission efficiency of the carriers in the middle connecting wire, thereby improving the photoelectric conversion efficiency of the back-contact photovoltaic cell.

[0043] 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 understood to indicate or imply relative importance or implicitly indicate the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined. Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0044] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0045] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0046] In the description of the embodiments of the present application, the technical terms "center," "longitudinal," "transverse," "length," "width," "thickness," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplification of the embodiments of the present application. They are not intended to indicate or imply that the devices or elements referred to must have, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the embodiments of the present application. For example, if the device or element in the figure is inverted, then an element described as being "below," "beneath," "under," or "below" another element or feature would be oriented "above" or "on top" of the other element or feature. Therefore, the term "below" can encompass both above and below orientations, depending on the context in which the term is used, as will be apparent to one of ordinary skill in the art. Materials can be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatially relative descriptors used herein should be interpreted accordingly.

[0047] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0048] In the accompanying drawings corresponding to the embodiments of the present application, the thickness and area of ​​each layer are exaggerated for better understanding and ease of description. In addition, when a component is described as being "substantially" 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.

[0049] In the description of the embodiments of the present application, when a certain component "includes" another component, unless otherwise stated, other components are not excluded, and other components may be further included. A second component is formed or provided above or on the first component, or a second component is formed or provided on the surface of the first component, or a second component is formed or provided on one side of the first component. Embodiments in which the first component and the second component are in direct contact may be included, and embodiments in which additional components may be provided between the first component and the second component so that the first component and the second component may not be in direct contact may also be included. For the sake of simplicity and clarity, various components may be arbitrarily drawn in different proportions. In the accompanying drawings, some layers / components may be omitted for simplicity. Unless otherwise specified, a second component is formed or provided on the surface of the first component, which means that the first component is in direct contact with the second component. Among them, the above-mentioned "components" may refer to layers, films, regions, parts, structures, etc.

[0050] The terms used herein in the description of the various embodiments are intended only to describe the specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is intended to include the plural form unless the context clearly indicates otherwise. A component includes a layer, film, region, or plate.

[0051] The following describes various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present disclosure to facilitate a better understanding of the present disclosure. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can still be implemented.

[0052] Figure 1 、 Figure 2 A schematic structural diagram of a back-contact photovoltaic cell provided in an embodiment of the present application.

[0053] refer to Figure 1 The back-contact photovoltaic cell includes: a cell body 100 , a grid line structure 200 and a connecting line 300 .

[0054] The battery body 100 has a first direction X and a second direction Y that intersect and are perpendicular to each other. The battery body 100 includes a central area 110 and edge areas 120 located on both sides of the central area 110 with respect to the first direction.

[0055] The fine grids include a current collecting grid 210 and a bus bar 220 ; the current collecting grid 210 and the bus bar 220 extend along a first direction X, and a plurality of the current collecting grids 210 and the bus bar 220 are sequentially arranged along a second direction Y; the current collecting grid 210 is disposed in the central area 110 and extends continuously along the first direction X; the bus bar 220 is disposed in the edge area 120 and extends intermittently along the first direction X;

[0056] The connecting wires 300 are disposed within the edge region 120 and are electrically connected to the bus bars 220 of the same polarity. The connecting wires 300 include a middle connecting wire 310 and side connecting wires 320 . The middle connecting wire 310 and the side connecting wires 320 extend along the second direction Y. A pair of side connecting wires 320 are disposed at the edges of the battery body 100 along the second direction Y, with the middle connecting wire 310 sandwiched between the pair of side connecting wires 320 .

[0057] In the first direction X, the width of the middle connecting line 310 is greater than the width of the side connecting line 320 .

[0058] The present application divides the grid line structure 200 of the battery body 100 into a current collecting grid 210 arranged in the central area 110 and a bus bar 220 arranged in the edge area 120. The current collecting grid 210 is directly electrically connected to the welding structure 400. The carriers collected by the current collecting grid 210 are transmitted to the welding structure 400 through a shorter transmission path, thereby improving the carrier transmission efficiency. The bus bar 220 of the same polarity is electrically connected to the welding structure 400 via a connecting wire 300. The width of the middle connecting wire 310 connecting more bus bar 220 is greater than the width of the side connecting wires 320 arranged on both sides and connecting fewer bus bar 220. The internal resistance of the middle connecting wire 310 with a larger width is smaller, thereby improving the transmission efficiency of the carriers in the middle connecting wire 310, thereby improving the photoelectric conversion efficiency of the back-contact photovoltaic cell. The setting of the connecting wire 300 in the edge area 120 reduces the number of welding structures 400 set in the edge area 120, avoids the problem of the battery body 100 being broken due to stress concentration during the welding process of the welding structure 400 and the welding strip, and the problem of the battery body 100 being warped due to the different expansion coefficients of the battery body 100 and the welding strip, thereby improving the yield rate of the production of back-contact photovoltaic cells and extending the service life of the back-contact photovoltaic cells.

[0059] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings.

[0060] like Figure 1 As shown, Figure 1A schematic structural diagram of a back-contact photovoltaic cell provided according to an embodiment of the present application is shown. The back-contact photovoltaic cell has a first direction X, a second direction Y and a third direction that intersect and are perpendicular to each other. The positive electrode and the negative electrode of the back-contact photovoltaic cell of the embodiment of the present application are both arranged on one side of the backlight surface of the battery body 100. The back-contact photovoltaic cell includes a battery body 100, a grid line structure 200, a connecting line 300 and a welding structure 400.

[0061] The battery body 100 is a rectangular sheet structure, and the battery body 100 has a photoelectric effect. The battery body 100 has a first surface and a second surface relative to each other in a third direction, and the third direction is the thickness direction of the battery body 100. The first surface of the battery body 100 is the light-facing surface of the back-contact photovoltaic cell of the embodiment of the present application, and the second surface of the battery body 100 is the backlight surface of the back-contact photovoltaic cell. The grid line structure 200, the connecting line 300 and the welding structure 400 are all arranged on the second surface of the battery body 100. In the first direction X, the battery body 100 has relative first edges 101; in the second direction Y, the battery body 100 has relative second edges 102. The battery body 100 includes a central area 110 and edge areas 120 arranged on both sides of the central area 110 with respect to the first direction X, that is, the edge areas 120 on both sides are respectively close to the relative second edges 102 of the battery body 100.

[0062] In some embodiments, the gate line structure 200 , the connection line 300 , and the welding structure 400 are formed on the second surface of the battery body 100 by a screen printing process.

[0063] In some embodiments, the battery body 100 can be divided into 1 / N whole battery cells, that is, the battery body 100 is N slices, N is a positive integer greater than 1; in other embodiments, the battery body 100 can also be composed of a whole battery cell, that is, the battery body 100 is a whole piece.

[0064] In some embodiments, the battery body 100 is formed by dividing a half of a whole battery cell, that is, the battery body 100 is a two-piece (half-piece).

[0065] In some embodiments, when the battery body 100 is formed by dividing the battery body 100 into 1 / N whole cells, the gridline structure 200, the connecting wire 300, and the welding structure 400 are first formed on the surface of the whole cell by a screen printing process, and then the whole cell is divided into N slices of the battery body 100 in the embodiment of this application to construct the back-contact photovoltaic cell in the embodiment of this application. In other embodiments, the battery body 100 is a whole cell, and the gridline structure 200, the connecting wire 300, and the welding structure 400 are formed on the surface of the battery body 100 by a screen printing process to directly construct the back-contact photovoltaic cell in the embodiment of this application.

[0066] A number of grid line structures 200 are arranged on the second side of the battery body 100 for collecting and transmitting photogenerated carriers, thereby realizing the electrical energy conversion of the back-contact photovoltaic cell. Since the positive electrode and the negative electrode of the back-contact photovoltaic cell of the embodiment of the present application are both arranged on the backlight side of the battery body 100, the polarity of the grid line structure 200 can be one of the positive and negative electrodes. The grid line structure 200 includes a current collecting grid 210 and a current bus grid 220. The current collecting grid 210 and the current bus grid 220 extend along the first direction X, and the current collecting grids 210 and the current bus grid 220 with different electrical properties are spaced apart along the second direction Y. The current collecting grid 210 is arranged in the central area 110, and the current collecting grid 210 is continuously arranged along the first direction X. The polarity of the adjacent current collecting grids 210 in the second direction Y is different. The bus bars 220 are disposed within the edge region 120. The bus bars 220 are intermittently arranged along the first direction X, extending along the same straight line with gaps 2201 between adjacent bus bars 220. The bus bars 220 extending along the same straight line have the same polarity; adjacent bus bars 220 in the second direction Y have different polarities. At the junction of the central region 110 and the edge region 120, adjacent bus bars 210 and bus bars 220 in the second direction Y have different polarities.

[0067] The connecting wires 300 are disposed within the edge region 120 to collect carriers transmitted by the current collecting grids 210. The connecting wires 300 extend along the second direction Y. The polarity of the connecting wires 300 can be either positive or negative, and the connecting wires 300 are electrically connected to the bus bars 220 of the same polarity. The connecting wires 300 include a middle connecting member and side connecting wires 320. Within the same edge region 120, two side connecting wires 320 are symmetrically disposed on either side of the edge region 120 with respect to the second direction Y. Specifically, the side connecting wires 320 on either side are located adjacent to the opposing first edges 101 of the battery body 100. The bus bars 220 and the middle connecting wire 310 are sandwiched between the symmetrical side connecting wires 320. The middle connecting wire 310 sequentially passes through the gaps 2201 between the bus bars 220 of different polarity along the second direction Y. The middle connecting wire 310 is electrically connected to the bus bars 220 of the same polarity disposed on either side of the middle connecting wire 310 with respect to the second direction Y. The side connection line 320 extends along the second direction Y and is electrically connected to the bus bars 220 disposed on one side thereof and having the same polarity.

[0068] The side connecting lines 320 and the middle connecting lines 310 are evenly spaced in the second direction Y, so that the lengths of the bus bars 220 connected by the side connecting lines 320 on both sides are equal, and the lengths of the middle connecting lines 310 connecting the bus bars 220 on both sides with respect to the second direction Y are equal. The even arrangement of the side connecting lines 320 and the middle connecting lines 310 reduces the overall internal resistance of the back-contact photovoltaic cell, improves the carrier transport efficiency, and thereby improves the photoelectric conversion efficiency of the back-contact photovoltaic cell.

[0069] Furthermore, in the first direction X, the width of the middle connecting line 310 is a first width W1, and the width of the side connecting line 320 is a second width W2, satisfying W1>W2. Because the side connecting line 320 is positioned at the edge of the cell body 100 near the first edge 101, only one side of the side connecting line 320 is electrically connected to the bus bars 220, while both sides of the middle connecting line 310 are electrically connected to the bus bars 220. Therefore, the total length of the bus bars 220 electrically connected by the side connecting line 320 is shorter than the total length of the bus bars 220 electrically connected by the middle connecting line 310. Therefore, the middle connecting line 310 needs to transport more units of carriers than the side connecting lines 320. The larger width of the middle connecting line 310 compared to the side connecting lines 320 reduces the internal resistance of the middle connecting line 310, improves the carrier transport efficiency of the middle connecting line 310, and thereby improves the photoelectric conversion efficiency of the back-contact photovoltaic cell. Compared with the related art, in which the width of the main grid (corresponding to the connecting line 300 in the embodiment of the present application) connected to the fine grid (corresponding to the gate line structure 200 in the embodiment of the present application) is designed to be either wide or narrow and of the same size, the embodiment of the present application makes the width of the middle 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 by the middle connecting line 310 and the side connecting line 320 and the total mobility of the required carrier transport. On the one hand, this improves the carrier transport efficiency, thereby improving the photoelectric conversion efficiency of the back-contact photovoltaic cell. On the other hand, it saves the slurry for making the connecting line 300 and reduces the production cost.

[0070] In some embodiments, the first width W1 of the intermediate connecting line 310 satisfies 250 μm ≤ W1 ≤ 400 μm. Preferably, the first width W1 of the intermediate connecting line 310 may be 280 μm, 300 μm, 350 μm, or 370 μm.

[0071] In some embodiments, the second width W2 of the side connection line 320 satisfies 50 μm ≤ W2 ≤ 250 μm. Preferably, the second width W2 of the side connection line 320 may be 60 μm, 100 μm, 150 μm, or 200 μm.

[0072] In some embodiments, the width of the current collecting and bus bar 210 and 220 in the first direction X is a third width W3, satisfying 15 μm≤W3≤50 μm. Preferably, the third width W3 of the current collecting and bus bar 210 and 220 may be 25 μm, 30 μm, 35 μm, or 40 μm.

[0073] Furthermore, at the position where the bus bars 220 with the same polarity are connected to the connection lines 300 , the bus bars 220 and the connection lines 300 are cross-connected.

[0074] In some embodiments, in the first direction X, the distance between the end of the bus bar 220 connected to the side connection line 320, which is closer 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 bar 220 protrudes from the side connection line 320 with the same polarity and to which it is connected. In the second direction Y, the distance between the end of the connecting line 300, which is closer to the second edge 102, and the second edge 102 is smaller than the distance between the bus bar 220 with the same polarity and closest to the second edge 102 and the second edge 102. In other words, the end of the connecting line 300 protrudes from the bus bar 220 with the same polarity and closest to the second edge 102. That is, the bus bar 220 extending in the first direction X passes through the connecting line 300 connected to it and closest to the first edge 101, and the connecting line 300 extending in the second direction Y passes through the connecting line 300 connected to it and closest to the second edge 102. This cross-connection structure ensures the connection effect between the bus bar 220 and the connecting line 300, avoiding the problem of the bus bar 220 not being connected to the connecting line 300 or having a poor connection due to printing errors.

[0075] Furthermore, in the second direction Y, a certain distance exists between the end of the intermediate connecting line 310 near the second edge 102 and the bus bar 220 having a different polarity and closest to the second edge 102. In other words, the end of the intermediate connecting line 310 near the second edge 102 does not protrude beyond the straight line along which the bus bar 220 having a different polarity and closest to the second edge 102 is located. In other words, the intermediate connecting line 310 and the bus bar 220 having a different polarity and closest to the second edge 102 are disconnected from each other in the second direction Y. This disconnection prevents short circuits caused by the connection between the intermediate connecting line 310 and the bus bar 220 due to printing errors or other reasons.

[0076] Several welding structures 400 are disposed on the second side of the cell body 100. These structures are electrically connected to the current collecting grid 210 or the connecting wires 300. These welding structures 400 are used to weld to the soldering ribbon. These welding structures 400 conduct the current generated by the back-contact photovoltaic cells to an external circuit, achieving a series-parallel connection between the back-contact photovoltaic cells and forming a complete current path.

[0077] The welding structure 400 includes a first welding portion 410 and a second welding portion 420. The first welding portion 410 is disposed within the edge region 120 and electrically connects to the connecting wire 300 within the edge region 120. The second welding portion 420 is disposed within the central region 110 and electrically connects to the current collecting grid 210 within the central region 110. Carriers collected by the current collecting grid 220 are sequentially transmitted to the external circuit via the connecting wire 300 and the first welding portion 410. This reduces the number of welding structures 400 disposed within the edge region 120, avoids stress concentration during welding between the welding structures 400 and the welding ribbon, and prevents cell body 100 fracture due to stress concentration, as well as cell body 100 warping due to the different expansion coefficients between the cell body 100 and the welding ribbon. This improves the yield rate of back-contact photovoltaic cells and extends the service life of back-contact photovoltaic cells. The carriers collected by the current collecting grid 210 are directly transmitted to the external circuit through the second welding portion 420. The transmission path is short, which improves the carrier transmission efficiency and thus improves the photoelectric conversion efficiency of the back-contact photovoltaic cell of the embodiment of the present application.

[0078] The first welding portions 410 and the second welding portions 420 of the same polarity are arranged sequentially along the second direction Y to facilitate welding connections with welding ribbons of the same polarity extending in the second direction Y. The second welding portions 420 of the same polarity are evenly distributed based on the number of the first welding portions 410 of the same polarity. The second welding portions 420 of the same polarity adjacent to each other in the second direction Y are alternately distributed back and forth in the first direction X, so that the second welding portions 420 in the central area 110 are evenly distributed, further preventing the occurrence of warping or cracking of the battery body 100 due to welding.

[0079] The first welding portions 410 are arranged in equal intervals along the first direction X so that after the first welding portions 410 and the second welding portions 420 are welded to the welding ribbon, the internal stress of the battery body 100 is evenly distributed, thereby preventing the battery body 100 from warping or breaking due to partial internal gravity concentration.

[0080] The first welding portion 410 is disposed at the end of the connecting line 300 close to the central area 110 , that is, the first welding portion 410 is disposed on the side of the edge area 120 away from the second edge 102 , further avoiding the occurrence of warping or cracking problems at the edge of the battery body 100 .

[0081] Furthermore, in the first direction X, the width of the first welding portion 410 is equal to the width of the second welding portion 420 , so that the first welding portion 410 and the second welding portion 420 can be formed synchronously during the printing process during the production process.

[0082] In the second direction Y, the length of the first welding portion 410 is a first length L1, and the length of the second welding portion 420 is a second length L2, satisfying L1>L2. The overall length of the bus bar 220 connected to the first welding portion 410 is greater than the length of the current collecting bar 210 connected to the second welding portion 420. The length of the first welding portion 410 is greater than the length of the second welding portion 420, thereby providing high carrier transmission efficiency.

[0083] 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 can be 0.8 mm, 1 mm, 1.2 mm, or 1.4 mm.

[0084] 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.

[0085] Furthermore, in the second direction Y, the length of the middle weld portion 411 is a third length L3, and the length of the side weld portion 412 is a fourth length L4, satisfying the relationship L3 < L4. Because the side weld portion 412 is located closer to the edge of the cell body 100 and is longer than the second weld portion 420, increasing the length of the side weld portion 412 increases the welding tension after the side weld portion 412 is connected to the welding ribbon, thereby improving the overall structural stability of the back-contact photovoltaic cell.

[0086] In some embodiments, the third length L3 of the middle weld portion 411 satisfies 0.4 mm ≤ L3 ≤ 0.8 mm. Preferably, the third length L3 of the middle weld portion 411 may be 0.5 mm, 0.6 mm, 0.65 mm, or 0.7 mm.

[0087] In some embodiments, the fourth length L4 of the side weld portion 412 satisfies 0.8 mm ≤ L4 ≤ 2.1 mm. Preferably, the fourth length L4 of the side weld portion 412 can be 0.95 mm, 1 mm, 1.2 mm, or 1.4 mm.

[0088] Furthermore, in the second direction Y, the spacing between adjacent current collectors or the spacing between adjacent bus bars 220 is a spacing length g, and the length of the side weld portion 412 is a fourth length L4, satisfying the condition 4g>L4>2g. The length of the side weld portion 412 is greater than twice the spacing length and less than four times the spacing length, so that the side weld portion 412 can pass through the gap 2201 between bus bars of different polarities to electrically connect to the bus bars 220 or current collector bars 210 of the same polarity. The side weld portion 412 can be directly electrically connected to the bus bars 220 or current collector bars 210, shortening the carrier transport path length, improving carrier transport efficiency, and thereby improving the photoelectric conversion efficiency of the back-contact photovoltaic cell.

[0089] In some embodiments, the spacing between adjacent current collecting gratings 210 or the spacing length g between adjacent bus bars 220 satisfies 0.5 mm ≤ g ≤ 2 mm. Preferably, the spacing between adjacent current collecting gratings 210 or the spacing length g between adjacent bus bars 220 can be 0.8 mm, 0.92 mm, 1 mm, or 1.2 mm.

[0090] The first welding portion 410 includes a middle welding portion 411 and a side welding portion 412. The middle welding portion 411 is electrically connected to the middle connecting line 310, and the side welding portion 412 is electrically connected to the side connecting line 320. The middle welding portion 411 and the side welding portion 412 are arranged in sequence along the first direction X in the same side area.

[0091] In the first direction X, the distance between the side welding portion 412 and its corresponding first edge 101 is smaller than the distance between the side connecting line 320 and the first edge 101. This makes the side welding portion 412 farther away from the first edge 101 than the side connecting line 320, further preventing the edge of the battery body 100 from warping or cracking.

[0092] The connecting wire 300 further includes an extended connecting wire 330 extending along the first direction X. The extended connecting wire 330 is disposed between the side welding portion 412 and the side connecting wire 320 . Both ends of the extended connecting wire 330 are electrically connected to the side welding portion 412 and the side connecting wire 320 , respectively.

[0093] Furthermore, in the second direction Y, the width of the extended connecting line 330 is a fourth width W4, and the second width W2 of the side connecting line 320 satisfies W2 = W4. The width of the extended connecting line 330 is equal to the width of the side extension line, thereby preventing an increase in the overall internal resistance of the side connecting line 320 and the extended connecting line 330 due to the width of the extended connecting line 330 being too small, thereby reducing the carrier transport efficiency of the side connecting line 320.

[0094] The busbar 220 also includes a break gate 221 disposed on the side of the side weld portion 412 near the first edge 101, and an extended connecting gate 230 for connecting the break gate 221 and the busbar 220. The break gate 221 and the busbar 220 of the same polarity extend along a first direction X, while the extended connecting gate 230 extends along a second direction Y and electrically connects the break gate 221 with adjacent busbars 220 or current collecting gates 210 of the same polarity. The provision of the break gate 221 and the extended connecting gate 230 increases the coverage of the gridline structure 200 on the surface of the cell body 100, thereby improving the photoelectric conversion efficiency of the back-contact photovoltaic cell.

[0095] In some embodiments, when the broken gate 221 is sandwiched between the side connection line 320 and the side welding portion 412, the extended connecting fine grid 230 connects the broken gate 221 and the bus bar 220, and the extended connecting fine grid passes through the gap between the bus bar 220 adjacent to the broken gate 221 and having a different polarity and the side connection line 320. In some embodiments, when the broken gate 221 is disposed on a side of the side welding portion 412 close to the first edge 101 and is not sandwiched by the side connection line 320, the extended connecting fine grid 230 connects the broken gate 221 and the bus bar 210, and the extended connecting fine grid 230 extends along the second direction Y on the side close to the first edge 101.

[0096] like Figure 2 As shown, Figure 2 A schematic diagram of the structure of a back-contact photovoltaic cell according to another embodiment of the present application is shown. In other embodiments, the back-contact photovoltaic cell further includes auxiliary connecting wires 340. The auxiliary connecting wires 340 are disposed on both sides of the cell body 100 near the first edge 101. The auxiliary connecting wires 340 extend along the second direction Y, penetrate the central region 110, and are electrically connected to the side connecting wires 320 on either side. The current collecting grid 210 within the central region 110 extends toward the auxiliary connecting wires 340 of the same polarity, so that the auxiliary connecting wires 340 are electrically connected to the current collecting grid 210 of the same polarity within the central region 110. The provision of the auxiliary connecting wires 340 enables carriers collected by the edge connecting wires 300 through the collecting grid 220 to be transferred to an external circuit not only through the side welds 412 but also through the second welds 420 on the current collecting grid 210. This reduces the overall internal resistance of the back-contact photovoltaic cell, improves carrier transfer efficiency, and thereby improves the photoelectric conversion efficiency of the back-contact photovoltaic cell.

[0097] Furthermore, the auxiliary connection line 340 is cross-connected to the current collecting grid 210, i.e., the distance between the end of the current collecting grid 210 electrically connected to the auxiliary connection line 340 and the first edge 101 is less than the distance between the auxiliary connection line 340 and the first edge 101. This cross-connection structure ensures a good connection between the current collecting grid 210 and the auxiliary connection line 340, and avoids problems such as the current collecting grid 210 not being connected to the auxiliary connection line 340 or having a poor connection due to printing errors.

[0098] In the first direction X, the width of the auxiliary connecting line 340 is a fifth width W5. The second width W2 of the side connecting line 320 and the third width W3 of the current collecting and bussing grids 210 and 220 satisfy the condition W2>W5>W3. The widths of the side connecting lines 320, auxiliary connecting lines 340, current collecting and bussing grids 210 and 220 are set based on the mobility of the carriers collected and transported. This, on the one hand, avoids the problem of high internal resistance caused by a uniformly small size, and on the other hand, avoids the problem of excessive slurry usage and increased production costs caused by a uniformly large size. The widths of the side connecting lines 320, auxiliary connecting lines 340, current collecting and bussing grids 210 and 220 improve carrier transport efficiency, thereby improving the photoelectric conversion efficiency of the back-contact photovoltaic cell and reducing production costs.

[0099] In some embodiments, the fifth width W5 of the auxiliary connection line 340 satisfies 30 μm< W5<200 μm. Preferably, the fifth width W5 of the auxiliary connection line 340 may be 50 μm, 70 μm, 85 μm, or 110 μm.

[0100] Accordingly, another embodiment of the present disclosure provides a photovoltaic module comprising a cell string, a welding ribbon, an encapsulating film, and a cover plate. The cell string is formed by connecting a plurality of back-contact photovoltaic cells, such as the back-contact photovoltaic cells in the above embodiment; the welding ribbon connects adjacent back-contact photovoltaic cells; the encapsulating film covers the surface of the back-contact photovoltaic cells; and the cover plate is located on the surface of the encapsulating film away from the back-contact photovoltaic cells. For portions identical or corresponding to the previous embodiment, reference may be made to the corresponding description of the previous embodiment and will not be repeated in detail below.

[0101] In some embodiments, when the battery body 100 is formed by dividing the battery body 100 into 1 / N whole battery cells, the grid line structure 200, the connecting line 300 and the welding structure 400 are first formed on the surface of the whole battery cell by a screen printing process, and then the whole battery cell is divided into N slices of the battery body 100 in the embodiment of the present application to construct a back-contact photovoltaic cell, and the welding ribbon connects adjacent back-contact photovoltaic cells to construct a battery string. In other embodiments, the battery body 100 is a whole cell, and the grid line structure 200, the connecting line 300 and the welding structure 400 are formed on the surface of the battery body 100 by a screen printing process to directly construct a back-contact photovoltaic cell, and the welding ribbon connects adjacent back-contact photovoltaic cells to construct a battery string.

[0102] The material of the encapsulation film can be an organic encapsulation film such as ethylene-vinyl acetate copolymer (EVA) film, polyethylene octene co-elastomer (POE) film or polyvinyl butyral (PVB) film.

[0103] The cover plate can be a glass cover plate, a plastic cover plate, or other light-transmitting cover plate. In some embodiments, the surface of the cover plate facing the film can be a concave-convex surface, thereby increasing the utilization rate of the incident light.

[0104] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present disclosure, and that in actual applications, various changes in form and detail may be made thereto without departing from the spirit and scope of the present disclosure. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be subject to the scope defined in the claims.

Claims

1. A back contact photovoltaic cell, characterized in that: include: A battery body (100), the battery body (100) having a first direction (X) and a second direction (Y) that intersect and are perpendicular to each other, the battery body (100) comprising a central area (110) and edge areas (120) located on both sides of the central area (110) with respect to the first direction (X); A gate line structure (200), the gate line structure (200) comprising a current collecting fine grid (210) and a current merging fine grid (220); the current collecting fine grid (210) and the current merging fine grid (220) extending along the first direction (X), and a plurality of the current collecting fine grids (210) and the current merging fine grids (220) being sequentially arranged along the second direction (Y); the current collecting fine grid (210) being arranged in the central area (110), and the current collecting fine grid (210) extending continuously along the first direction (X); the current merging fine grid (220) being arranged in the edge area (120), and the current merging fine grid (220) extending discontinuously along the first direction (X); a connecting line (300), the connecting line (300) being arranged in the edge region (120), the connecting line being electrically connected to a busbar (220) having the same polarity as the connecting line; the connecting line comprising a middle connecting line (310) and a side connecting line (320), the middle connecting line (310) and the side connecting line (320) extending along the second direction (Y); a pair of the side connecting lines (320) being arranged at both side edge positions of the battery body (100) with respect to the second direction (Y), the middle connecting line (310) being sandwiched between the pair of the side connecting lines (320); Welding structures (400), wherein a plurality of the welding structures (400) are electrically connected to the current collecting grid (210) or the connecting wire (300); Wherein, in the first direction (X), the width of the middle connecting line (310) is greater than the width of the side connecting line (320).

2. The back contact photovoltaic cell according to claim 1, characterized in that In the first direction (X), the width of the middle connecting line (310) is a first width W1, and the width of the side connecting line (320) is a second width W2; in the second direction (Y), the width of the current collecting grid (210) and the current collecting grid (220) is a third width W3; wherein W1>W2>W3, 400μm≥W1≥250μm, 250μm≥W2≥50μm.

3. The back contact photovoltaic cell according to claim 1, characterized in that The welding structure (400) comprises: a first welding portion (410), the first welding portion (410) being arranged on a side of the edge region (120) close to the central region (110), the first welding portion (410) being electrically connected to the connecting wire (300) having the same polarity; A second welding portion (420), the second welding portion (420) is arranged in the central area (110), and the second welding portion (420) is electrically connected to the current collecting grid (210).

4. The back contact photovoltaic cell according to claim 3, characterized in that: There is a gap (2201) between the adjacent bus bars (220) extending along the same straight line; The first welding portion (410) is electrically connected to the bus bar (220) with the same polarity and closest to the central area (110) in the edge area (120); after the first welding portion (410) passes through the gap (2201) between the bus bar (220) adjacent to each other in the second direction (Y) and with different polarities, the first welding portion (410) is electrically connected to another bus bar (220) with the same polarity or the current collecting bar (210).

5. The back contact photovoltaic cell according to claim 3 or 4, characterized in that: The first welding portion (410) comprises a middle welding portion (411) and a side welding portion (412), the middle welding portion (411) is electrically connected to the middle connecting line (310), and the side welding portion (412) is electrically connected to the side connecting line (320); The connecting line also includes an extended connecting line (330); The distance between the side welding portion (412) and the first edge (101) corresponding thereto is greater than the distance between the side connection line (320) electrically connected thereto and the first edge (101), and the side welding portion (412) is electrically connected to the side connection line (320) via the extended connection line (330) extending along the first direction (X).

6. The back contact photovoltaic cell according to claim 5, characterized in that: In the second direction (Y), the length of the side welding portion (412) is a fourth length L4, and the spacing dimension between adjacent current collecting grids (210) or the current collecting grids (220) is a spacing length g, wherein 4g>L4>2g.

7. The back contact photovoltaic cell according to claim 5, characterized in that: In the second direction (Y), the length of the middle welding portion (411) is a third length L3, and the length of the side welding portion (412) is a fourth length L4, wherein L4>L3.

8. The back contact photovoltaic cell according to claim 6, characterized in that: The busbar (220) includes a break grid (221) provided on a side of the side welding portion (412) facing the edge of the battery body (100) corresponding thereto; The grid line structure (200) further comprises: an extended connecting fine grid (230), the extended connecting fine grid (230) extending along the second direction (Y), the extended connecting fine grid (230) being arranged on a side of the side welding portion (412) facing the edge of the battery body (100) corresponding thereto, and the two ends of the extended connecting fine grid (230) being electrically connected to the broken grid (221) and the busbar fine grid (220) of the same polarity, respectively.

9. The back contact photovoltaic cell according to claim 1, characterized in that: The two end edges of the battery body (100) extending along the first direction (X) are first edges (101), and the two end edges of the battery body (100) extending along the second direction (Y) are second edges (102); wherein the distance between one end of the connecting line in the second direction (Y) and the corresponding second edge (102) is smaller than the distance between any busbar (220) electrically connected thereto and the second edge (102); The distance between one end of the busbar (220) electrically connected to the side connection line (320) in the first direction (X) and the first edge (101) corresponding thereto is smaller than the distance between the side connection line (320) and the first edge (101).

10. The back contact photovoltaic cell according to claim 1, characterized in that: It also includes an auxiliary connection line (340), which passes through the central area (110) along the second direction (Y) and is electrically connected to the side connection lines (320) on both sides; the auxiliary connection line (340) is electrically connected to the current collecting grid (210) with the same polarity.

11. The back contact photovoltaic cell according to claim 10, characterized in that: The two end edges of the battery body (100) extending along the first direction (X) are first edges (101), and the two end edges of the battery body (100) extending along the second direction (Y) are second edges (102); The distance between one end of the current collecting grid (210) electrically connected to the auxiliary connecting line (340) and the first edge (101) is smaller than the distance between the auxiliary connecting line (340) and the first edge (101).

12. The back contact photovoltaic cell according to claim 10, characterized in that: In the first direction (X), the width of the side connection line (320) is a second width W2, and the width of the auxiliary connection line (340) is a fifth width W5, wherein W2>W5, 250μm≥W2≥50μm, and 200μm≥W5≥30μm.

13. A photovoltaic module, characterized in that: include: A cell string, wherein the cell string is composed of a plurality of back-contact photovoltaic cells connected together, and the back-contact photovoltaic cell is the back-contact photovoltaic cell according to any one of claims 1 to 12; a welding ribbon connecting adjacent back-contact photovoltaic cells; an encapsulation film, the encapsulation film covering the surface of the back-contact photovoltaic cell; A cover plate is located on a surface of the packaging film away from the back contact photovoltaic cell.

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