Back contact photovoltaic cell and photovoltaic module

Abstract

The invention relates to the field of photovoltaic cells, and provides a back contact photovoltaic cell and a photovoltaic module, and the back contact photovoltaic cell comprises a cell body which comprises a central region and edge regions at the two sides of the central region; the fine grids comprise current collecting fine grids and confluence fine grids; the collector fine grid is arranged in the central area and continuously extends along a first direction; the confluence fine grid is arranged in the edge area and intermittently extends along a first direction; the connecting line is arranged in the edge area; the connecting lines comprise a middle connecting line and side connecting lines; the pair of side connecting lines are arranged at the edges of the two sides of the battery body, and the middle connecting line is clamped between the pair of side connecting lines; the plurality of welding structures are electrically connected with the current collecting fine grids or the connecting lines; wherein the width of the middle connecting line is larger than that of the side connecting lines. According to the embodiment of the invention, the problem of low transmission efficiency of carriers on a path of connecting the main grid with the fine grid can be solved at least.

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 the interdigitated back contact (IBC) cell is that the PN junction and the contact metal are both on the back of the IBC cell. The front of the IBC cell completely avoids the shading of the metal grid electrode, which can maximize the use of incident light, reduce optical losses, and have a higher short-circuit current.

[0003] In the related art, a back contact cell usually has a main grid connected to fine grids of the same polarity, and then uses the pads on the main grid to weld to the welding strip. However, the carriers on the fine grid that are not connected to the welding pad need to be first transferred to the main grid, and then transferred to the welding strip through the welding pad. This transmission path is long and the carrier transmission efficiency is low.

[0004] Therefore, how to design a back-contact photovoltaic cell with high transmission efficiency is a problem that technicians in this field need to solve. 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 on 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 on one hand, and the back-contact photovoltaic cell includes: 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 area and edge areas located on both sides of the central area with respect to the first direction; A gate line structure, wherein the fine grid includes a current collecting fine grid and a current merging fine grid; the current collecting fine grid and the current merging fine grid extend along the first direction, and a plurality of the current collecting fine grids and the current merging fine grids are sequentially arranged along the second direction; the current collecting fine grid is arranged in the central area, and the current collecting fine grid extends continuously along the first direction; the current merging fine grid is arranged in the edge area, and the current merging fine grid extends discontinuously along the first direction; A connecting line, wherein the connecting line is arranged in the edge area, and the connecting line is electrically connected to a bus bar having the same polarity as the connecting line; the connecting line comprises a middle connecting line and a side connecting line, and the middle connecting line and the side connecting line extend along the second direction; a pair of the side connecting lines are arranged at the edge positions of both sides of the battery body with respect to the second direction, and the middle connecting line is sandwiched between the pair of the side connecting lines; Welding structures, some of which are electrically connected to the current collecting grid or the connecting wire; Wherein, in the first direction, the width of the middle connecting line is greater than the width of the side connecting line.

[0007] 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.

[0008] In some embodiments, the welded structure comprises: A first welding portion, the first welding portion is arranged at a side of the edge region close to the central region, and the first welding portion is electrically connected to a connection line with the same polarity; A second welding portion, wherein the second welding portion is disposed in the central region, and the second welding portion is electrically connected to the current collecting grid.

[0009] In some embodiments, there is a gap between the adjacent bus bars extending along the same straight line; The first welding portion is electrically connected to the bus fine grid with the same polarity that is closest to the central area in the edge area. After the first welding portion passes through the gap between adjacent bus fine grids with different polarities in the second direction, the first welding portion is electrically connected to another bus fine grid or the current collecting fine grid with the same polarity.

[0010] 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; The connecting line also includes an extension connecting line; The distance between the side welding portion and the first edge corresponding to it is greater than the distance between the side connection line electrically connected to it 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.

[0011] 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.

[0012] 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.

[0013] In some embodiments, the busbar includes a break grid disposed on a side of the side welding portion facing the edge of the battery body corresponding thereto; The grid line structure also includes: an extended connecting fine grid, which extends along the second direction, and is arranged on a side of the side welding portion facing the edge of the battery body corresponding thereto, and two ends of the extended connecting fine grid are respectively electrically connected to the broken grid and a bus fine grid with the same polarity.

[0014] 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; Wherein, the distance between one end of the connecting line in the second direction and the second edge corresponding thereto is smaller than the distance between any bus bar electrically connected thereto and the second edge; 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.

[0015] In some embodiments, an auxiliary connection line is further included, wherein the auxiliary connection line 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.

[0016] 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; The distance between one end of the current collecting fine 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.

[0017] 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.

[0018] According to some embodiments of the present disclosure, the embodiments of the present application further provide a photovoltaic module, wherein the photovoltaic module comprises a cell string, wherein the cell string is composed of a plurality of back-contact photovoltaic cells connected, and the back-contact photovoltaic cell is the back-contact photovoltaic cell as described in any one of the above items; 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.

[0019] The technical solution provided by the embodiment of the present application has at least the following advantages: the present application sets the grid line structure in the central area of ​​the battery body as a current collecting grid, and the grid line structure in the edge area as a current collecting 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 short, thereby improving the transmission efficiency of the carriers. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings, and these exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, 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 are 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 creative work.

[0021] Figure 1 A schematic diagram of the structure of a back-contact photovoltaic cell provided according to an embodiment of the present application; Figure 2 A schematic structural diagram of a back-contact photovoltaic cell provided according to another embodiment of the present application.

[0022] 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

[0023] As can be seen from the background technology, in the related art, a main grid is usually set to connect the grid line structures of the same polarity, and then the welding structure on the main grid is used to weld with the welding strip to reduce the setting of the welding structure. However, in this structure, the carriers on the grid line structure that is not connected to the welding structure need to be first transmitted to the main grid, and then transferred to the welding strip through the welding structure. The transmission efficiency of the carriers on this path is low, thereby affecting the photoelectric conversion efficiency of the back contact photovoltaic cell, and the setting of the main grid will increase the cost of the slurry.

[0024] The present disclosure provides a back-contact photovoltaic cell, which is implemented by setting the grid line structure in the central area of ​​the battery 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 short, which improves 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 arranged on both sides and connecting fewer busbar grids. The internal resistance of the middle connecting wire with a larger width is smaller, which improves the transmission efficiency of the carriers in the middle connecting wire, thereby improving the photoelectric conversion efficiency of the back-contact photovoltaic cell.

[0025] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present 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).

[0026] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0027] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0028] In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application. For example, if the device or element in the figure is inverted, then the element described as being "below" or "below" or "below" or "bottom" of other elements or features will be oriented "above" or "top" of the other elements or features. Therefore, the term "below" may cover both the above and below orientations depending on the context in which the term is used, which will be obvious to a person of ordinary skill in the art. The material can be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatially relative descriptors used herein can be interpreted accordingly.

[0029] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0030] In the accompanying drawings corresponding to the embodiments of the present application, the thickness and area of ​​the layers are exaggerated for better understanding and ease of description. In addition, when describing that a component is "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 partial edge of the entire surface.

[0031] In the description of the embodiments of the present application, when a certain component "includes" another component, unless otherwise specified, 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, which may include an embodiment in which the first component and the second component are in direct contact, and may also include an embodiment in which an additional component 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. For the sake of simplicity and clarity, various components may be drawn arbitrarily 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 "component" may refer to a layer, a film, an area, a part, a structure, etc.

[0032] The terms used in the description of the various embodiments described herein are only used to describe specific embodiments and are not intended to be limiting. As used in the description of the various embodiments described and in the appended claims, "the components" are also intended to include plural forms unless the context clearly indicates otherwise. Among them, components include components such as layers, films, regions, or plates.

[0033] The following will describe the various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present disclosure, many technical details are provided in order to enable the reader to better understand the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can be implemented.

[0034] Figure 1 , Figure 2 A schematic diagram of the structure of a back-contact photovoltaic cell provided in an embodiment of the present application.

[0035] refer to Figure 1 The back-contact photovoltaic cell includes: a cell body 100 , a grid line structure 200 and a connecting line 300 .

[0036] 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. The fine grids include a current collecting fine grid 210 and a bus fine grid 220; the current collecting fine grid 210 and the bus fine grid 220 extend along a first direction X, and a plurality of current collecting fine grids 210 and the bus fine grid 220 are sequentially arranged along a second direction Y; the current collecting fine grid 210 is arranged in the central area 110, and the current collecting fine grid 210 extends continuously along the first direction X; the bus fine grid 220 is arranged in the edge area 120, and the bus fine grid 220 extends intermittently along the first direction X; The connection wire 300 is arranged in the edge area 120, and the connection wire 300 is electrically connected to the bus bar 220 with the same polarity; the connection wire 300 includes a middle connection wire 310 and a side connection wire 320, and the middle connection wire 310 and the side connection wire 320 extend along the second direction Y; a pair of side connection wires 320 are arranged at the edge positions of both sides of the battery body 100 with respect to the second direction Y, and the middle connection wire 310 is sandwiched between the pair of side connection wires 320; In the first direction X, the width of the middle connection line 310 is greater than the width of the side connection line 320 .

[0037] 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 current bus grid 220 arranged in the edge area 120. The current collecting grid 210 is directly electrically connected to the welding structure 400, and the transmission path of the carriers collected by the current collecting grid 210 to the welding structure 400 is short, which improves the transmission efficiency of the carriers. The current bus grids 220 of the same polarity are electrically connected to the welding structure 400 through the connecting wires 300. The width of the middle connecting wire 310 connecting more current bus grids 220 is greater than the width of the side connecting wires 320 arranged on both sides and connecting fewer current bus grids 220. The internal resistance of the middle connecting wire 310 with a larger width is smaller, which improves 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 back-contact photovoltaic cells and extending the service life of the back-contact photovoltaic cells.

[0038] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings.

[0039] 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 are intersecting and perpendicular. 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.

[0040] 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 a relative first edge 101; in the second direction Y, the battery body 100 has a relative second edge 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.

[0041] In some embodiments, the grid 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.

[0042] 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.

[0043] In some embodiments, the battery body 100 is divided into 1 / 2 of a whole battery cell, that is, the battery body 100 is divided into two pieces (half pieces).

[0044] In some embodiments, when the battery body 100 is formed by dividing 1 / N whole battery cells, the grid line structure 200, the connecting wire 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 pieces of the battery body 100 in the embodiment of the present application to construct the back contact photovoltaic cell in the embodiment of the present application. In other embodiments, the battery body 100 is a whole piece, and the grid line 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 the present application.

[0045] A plurality of gridline structures 200 are arranged on the second surface of the battery body 100 for collecting and transmitting photogenerated carriers, thereby realizing the electric 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 surface of the battery body 100, the polarity of the gridline structure 200 can be one of the positive electrode and the negative electrode. The gridline 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 grid 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 polarities of the adjacent current collecting grids 210 in the second direction Y are different. The bus bars 220 are arranged in the edge region 120, and the bus bars 220 are arranged intermittently along the first direction X, extending along the same straight line and with gaps 2201 between adjacent bus bars 220. The bus bars 220 extending along the same straight line have the same polarity; the adjacent bus bars 220 in the second direction Y have different polarities. In the region where the central region 110 and the edge region 120 intersect, the adjacent current collecting bars 210 and bus bars 220 in the second direction Y have different polarities.

[0046] The connection line 300 is arranged in the edge area 120 to collect the carriers transmitted by the current collecting grid 210. The connection line 300 extends along the second direction Y. The polarity of the connection line 300 can be one of the positive pole and the negative pole. The connection piece is electrically connected to the bus bar 220 with the same polarity. The connection line 300 includes an intermediate connection piece and a side connection line 320. Among them, in the same edge area 120, two side connection lines 320 are symmetrically arranged on both sides of the edge area 120 with respect to the second direction Y, that is, the side connection lines 320 on both sides are respectively close to the first edge 101 opposite to the battery body 100; the bus bar 220 and the intermediate connection line 310 are sandwiched between the symmetrical side connection lines 320. The intermediate connection line 310 passes through the gap 2201 between the bus bar 220 with different polarity in sequence along the second direction Y, and the intermediate connection line 310 is electrically connected to the bus bar 220 arranged on both sides of the second direction Y and with the same polarity. The side connection line 320 extends along the second direction Y and is electrically connected to the bus bar 220 disposed on one side thereof and having the same polarity.

[0047] The side connection lines 320 and the middle connection lines 310 are evenly arranged in sequence in the second direction Y, so that the lengths of the bus bars 220 connected by the side connection lines 320 on both sides are equal, and the lengths of the middle connection lines 310 connected to the bus bars 220 on both sides about the second direction Y are equal. The uniform arrangement of the side connection lines 320 and the middle connection lines 310 reduces the overall internal resistance of the back contact photovoltaic cell, improves the carrier transport efficiency, and thus improves the photoelectric conversion efficiency of the back contact photovoltaic cell.

[0048] Further, in the first direction X, the width of the middle connection line 310 is the first width W1, and the width of the side connection line 320 is the second width W2, satisfying W1>W2. Since the side connection line 320 is disposed at the edge of the battery body 100 close to the first edge 101, only one side of the side connection line 320 is electrically connected to the bus grid 220, while both sides of the middle connection line 310 are electrically connected to the bus grid 220, so the overall length of the bus grid 220 electrically connected by the side connection line 320 is less than the overall length of the bus grid 220 electrically connected by the middle connection line 310, and the middle connection line 310 needs to transmit more units of carriers than the side connection line 320. The middle connection line 310 has a larger width dimension than the side connection line 320, which reduces the internal resistance of the middle connection line 310, improves the carrier transportation efficiency of the middle connection line 310, and thus improves the photoelectric conversion efficiency of the back contact photovoltaic cell. Compared to 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 grid line structure 200 in the embodiment of the present application) is designed to be either wide or narrow but 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 transported carriers. 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.

[0049] In some embodiments, the first width W1 of the intermediate connection line 310 satisfies 250 μm≤W1≤400 μm. Preferably, the first width W1 of the intermediate connection line 310 may be 280 μm, 300 μm, 350 μm or 370 μm.

[0050] 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.

[0051] In some embodiments, in the first direction X, the width of the current collecting grating 210 and the bus grating 220 is a third width W3, satisfying 15 μm≤W3≤50 μm. Preferably, the third width W3 of the current collecting grating 210 and the bus grating 220 may be 25 μm, 30 μm, 35 μm or 40 μm.

[0052] Furthermore, at the position where the bus bar 220 and the connection line 300 with the same polarity are connected, the bus bar 220 and the connection line 300 are cross-connected.

[0053] 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 close to the first edge 101 and the first edge 101 is smaller than the distance between the side connection line 320 and the first edge 101. In other words, the end of the bus bar 220 protrudes from the side connection line 320 with the same polarity and connected thereto. In the second direction Y, the distance between the end of the connection line 300 close 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 connection line 300 protrudes from the bus bar 220 with the same polarity and connected thereto 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.

[0054] Further, in the second direction Y, there is a certain distance between the end of the intermediate connecting line 310 close to the second edge 102 and the bus bar 220 with different polarity and closest to the second edge 102. In other words, the end of the intermediate connecting line 310 close to the second edge 102 does not protrude from the straight line where the bus bar 220 with different polarity and closest to the second edge 102 is located. That is, the intermediate connecting line 310 and the bus bar 220 with different polarity and closest to the second edge 102 are disconnected from each other in the second direction Y, and the disconnection structure avoids the occurrence of a short circuit problem caused by the connection between the two due to printing errors and other reasons.

[0055] A plurality of welding structures 400 are disposed on the second surface of the battery body 100, and the welding structures 400 are electrically connected to the current collecting grid 210 or the connecting wire 300. The welding structures 400 are used to weld with the welding strip, and the welding structures 400 conduct the current generated by the back contact photovoltaic cell to the external circuit, realize the series-parallel connection between the back contact photovoltaic cells, and form a complete current path.

[0056] The welding structure 400 includes a first welding portion 410 and a second welding portion 420. The first welding portion 410 is arranged in the edge area 120, and the first welding portion 410 is electrically connected to the connecting wire 300 in the edge area 120; the second welding portion 420 is arranged in the central area 110, and the second welding portion 420 is electrically connected to the collector grid 210 in the central area 110. The carriers collected by the collector grid 220 are sequentially transmitted to the external circuit through the connecting wire 300 and the first welding portion 410, thereby reducing the number of welding structures 400 arranged in the edge area 120, avoiding 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. 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 transmission efficiency of the carriers and further improves the photoelectric conversion efficiency of the back contact photovoltaic cell of the embodiment of the present application.

[0057] The first welding parts 410 and the second welding parts 420 with the same polarity are arranged in sequence along the second direction Y, so as to be welded and connected with the welding strips extending in the second direction Y and with the same polarity. The second welding parts 420 with the same polarity are evenly distributed according to the number of the first welding parts 410 with the same polarity, and the second welding parts 420 with 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 parts 420 in the central area 110 are evenly distributed, further avoiding the problem of warping or fragmentation of the battery body 100 caused by welding.

[0058] The first welding parts 410 are arranged in sequence along the first direction X at equal intervals, so that after the first welding parts 410 and the second welding parts 420 are welded to the welding strip, the internal stress of the battery body 100 is evenly distributed, thereby avoiding the problem of warping or breaking of the battery body 100 due to partial internal gravity concentration.

[0059] 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 .

[0060] 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.

[0061] In the second direction Y, the length dimension of the first welding portion 410 is the first length L1, and the length dimension of the second welding portion 420 is the 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 collector bar 210 connected to the second welding portion 420, and the length dimension of the first welding portion 410 is greater than the length dimension of the second welding portion 420, so as to provide high carrier transmission efficiency.

[0062] In some embodiments, the first length L1 of the first welding portion 410 satisfies 0.4 mm ≤ L1 ≤ 2.1 mm. Preferably, the first length L1 of the first welding portion 410 may be 0.8 mm, 1 mm, 1.2 mm or 1.4 mm.

[0063] 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.

[0064] Further, in the second direction Y, the length dimension of the middle welding portion 411 is the third length L3, and the length dimension of the side welding portion 412 is the fourth length L4, satisfying L3<L4. Since the side welding portion 412 is disposed closer to the edge of the battery body 100 and its length dimension is greater than the second welding portion 420, the length dimension of the side welding portion 412 is increased to increase the welding tension after the side welding portion 412 is connected to the welding strip, thereby improving the stability of the overall structure of the back contact photovoltaic cell.

[0065] In some embodiments, the third length L3 of the middle welding portion 411 satisfies 0.4 mm ≤ L3 ≤ 0.8 mm. Preferably, the third length L3 of the middle welding portion 411 may be 0.5 mm, 0.6 mm, 0.65 mm or 0.7 mm.

[0066] In some embodiments, the fourth length L4 of the side welding portion 412 satisfies 0.8 mm ≤ L4 ≤ 2.1 mm. Preferably, the fourth length L4 of the side welding portion 412 may be 0.95 mm, 1 mm, 1.2 mm or 1.4 mm.

[0067] Further, in the second direction Y, the spacing dimension between adjacent current collectors or the spacing dimension between adjacent busbars 220 is the spacing length g, and the length dimension of the side welding portion 412 is the fourth length L4, satisfying 4g>L4>2g. The length dimension of the side welding portion 412 is greater than twice the spacing length and less than four times the spacing length, so that the side welding portion 412 can pass through the gap 2201 between the busbars of different polarities to be electrically connected to the busbars 220 or current collectors 210 of the same polarity, and the side welding portion 412 can be directly connected to the busbars 220 or current collectors 210, thereby shortening the carrier transport path length, improving the carrier transport efficiency, and thereby improving the photoelectric conversion efficiency of the back contact photovoltaic cell.

[0068] In some embodiments, the spacing dimension between adjacent current collecting gratings 210 or the spacing length g between adjacent bus gratings 220 satisfies 0.5 mm ≤ g ≤ 2 mm. Preferably, the spacing dimension between adjacent current collecting gratings 210 or the spacing length g between adjacent bus gratings 220 may be 0.8 mm, 0.92 mm, 1 mm or 1.2 mm.

[0069] 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 connection line 310, and the side welding portion 412 is electrically connected to the side connection line 320. The middle welding portion 411 and the side welding portion 412 disposed in the same side area are arranged in sequence along the first direction X.

[0070] In the first direction X, the distance between the side welding portion 412 and the corresponding first edge 101 is smaller than the distance between the side connecting line 320 and the first edge 101, so that the side welding portion 412 is farther away from the first edge 101 than the side connecting line 320, further avoiding the occurrence of warping or cracking at the edge of the battery body 100.

[0071] 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.

[0072] Further, in the second direction Y, the width of the extended connection line 330 is the fourth width W4, and the second width W2 of the side connection line 320 satisfies W2=W4. The width of the extended connection line 330 is equal to the width of the side extension line, so as to avoid the increase of the overall internal resistance of the side connection line 320 and the extended connection line 330 due to the small width of the extended connection line 330, thereby reducing the carrier transport efficiency of the side connection line 320.

[0073] The bus fine grid 220 also includes a broken grid 221 disposed on the side of the side welding portion 412 close to the first edge 101, and an extended connecting grid 230 for connecting the broken grid 221 and the bus fine grid 220. The broken grid 221 and the bus fine grid 220 of the same polarity extend along the first direction X, and the extended connecting grid 230 extends along the second direction Y and electrically connects the broken grid 221 and the bus fine grid 220 or the current collecting grid 210 of the same polarity and adjacent to the broken grid 221. The broken grid 221 and the extended connecting grid 230 are provided to improve the coverage of the grid line structure 200 on the surface of the battery body 100, thereby improving the photoelectric conversion efficiency of the back contact photovoltaic cell.

[0074] In some embodiments, when the broken gate 221 is sandwiched between the side connection line 320 and the side welding portion 412, the extended connection fine grid 230 connects the broken gate 221 and the bus fine grid 220, and the extended connection fine grid passes through the gap between the bus fine grid 220 and the side connection line 320 that is adjacent to the broken gate 221 and has a different polarity. 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 connection fine grid 230 connects the broken gate 221 and the current collecting fine grid 210, and the extended connection fine grid 230 extends along the second direction Y on the side close to the first edge 101.

[0075] like Figure 2 As shown, Figure 2 The schematic diagram of the structure of a back-contact photovoltaic cell provided according to another embodiment of the present application is shown. In other embodiments, the back-contact photovoltaic cell further includes an auxiliary connection line 340, which is arranged on both sides of the battery body 100 near the first edge 101, and extends along the second direction Y. The auxiliary connection line 340 runs through the central area 110 and is electrically connected to the side connection lines 320 on both sides. The current collecting grid 210 in the central area 110 extends toward the auxiliary connection line 340 with the same polarity, so that the auxiliary connection line 340 is electrically connected to the current collecting grid 210 with the same polarity in the central area 110. The setting of the auxiliary connection line 340 enables the carriers collected by the edge connection line 300 through the collecting grid 220 to be transmitted to the external circuit not only through the side welding portion 412, but also through the second welding portion 420 on the current collecting grid 210, thereby reducing the overall internal resistance of the back-contact photovoltaic cell, improving the transmission efficiency of the carriers, and thus improving the photoelectric conversion efficiency of the back-contact photovoltaic cell.

[0076] Furthermore, the auxiliary connection line 340 is cross-connected with the current collecting fine grid 210, that is, the distance between one end of the current collecting fine grid 210 electrically connected to the auxiliary connection line 340 and the first edge 101 is smaller than the distance between the auxiliary connection line 340 and the first edge 101. This cross-connection structure ensures the connection effect between the current collecting fine grid 210 and the auxiliary connection line 340, and avoids the problem that the current collecting fine grid 210 is not connected to the auxiliary connection line 340 or the connection is poor due to printing errors.

[0077] In the first direction X, the width of the auxiliary connection line 340 is the fifth width W5, the second width W2 of the side connection line 320, and the third width W3 of the current collecting grid 210 and the bus grid 220 satisfy W2>W5>W3. The width is set according to the carrier mobility collected and transmitted by the side connection line 320, the auxiliary connection line 340, the current collecting grid 210, and the bus grid 220, on the one hand, to avoid the problem of large internal resistance caused by a smaller uniform size, and on the other hand, to avoid the problem of excessive slurry usage and increased production cost caused by a larger uniform size. The width setting of the side connection line 320, the auxiliary connection line 340, the current collecting grid 210, and the bus grid 220 improves the carrier transport efficiency, thereby improving the photoelectric conversion efficiency of the back contact photovoltaic cell and reducing the production cost.

[0078] 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.

[0079] Correspondingly, another embodiment of the present disclosure further provides a photovoltaic module, which includes a cell string, a welding ribbon, a packaging film and a cover plate. The cell string is formed by connecting a number 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 packaging film covers the surface of the back-contact photovoltaic cell; and the cover plate is located on the surface of the packaging film away from the back-contact photovoltaic cell. For the parts that are the same or corresponding to the previous embodiment, reference can be made to the corresponding description of the previous embodiment, and will not be described in detail below.

[0080] In some embodiments, when the battery body 100 is divided 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 pieces of the battery body 100 in the embodiment of the present application to construct a back-contact photovoltaic cell, and the welding strips connect adjacent back-contact photovoltaic cells to construct a battery string. In other embodiments, the battery body 100 is a whole piece, 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 strips connect adjacent back-contact photovoltaic cells to construct a battery string.

[0081] The material of the packaging film can be an organic packaging film such as ethylene-vinyl acetate copolymer (EVA) film, polyethylene octene co-elastomer (POE) film or polyvinyl butyral (PVB) film.

[0082] The cover plate can be a glass cover plate, a plastic cover plate or the like with a light-transmitting function. In some embodiments, the surface of the cover plate facing the adhesive film can be a concave-convex surface, thereby increasing the utilization rate of the incident light.

[0083] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for realizing the present disclosure, and in practical applications, various changes can be made to them in form and details without departing from the spirit and scope of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, so the protection scope of the present disclosure shall be based on 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 bus fine grid (220); the current collecting fine grid (210) and the current bus fine grid (220) extend along the first direction (X), and a plurality of the current collecting fine grids (210) and the current bus fine grids (220) are sequentially arranged along the second direction (Y); the current collecting fine grid (210) is arranged in the central area (110), and the current collecting fine grid (210) extends continuously along the first direction (X); the current bus fine grid (220) is arranged in the edge area (120), and the current bus fine grid (220) extends discontinuously along the first direction (X); A connecting line (300), the connecting line (300) being arranged in the edge area (120), the connecting line being electrically connected to a bus bar (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 the edge positions of both sides 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), a plurality of the welding structures (400) being electrically connected to the current collecting grid (210) or the connecting wire (300); Wherein, in the first direction (X), the width of the middle connection line (310) is greater than the width of the side connection 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 connection line (310) is a first width W1, and the width of the side connection line (320) is a second width W2; in the second direction (Y), the widths of the current collecting fine grid (210) and the current collecting fine grid (220) are 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) being arranged in the central area (110), the second welding portion (420) being 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 fine grid (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 adjacent bus fine grids (220) with different polarities in the second direction (Y), the first welding portion (410) is electrically connected to another bus fine grid (220) with the same polarity or the current collecting fine grid (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 to it 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 fine grids (210) or bus bar fine 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) comprises a break grid (221) arranged 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 respectively electrically connected to the broken grid (221) and the busbar fine grid (220) of the same polarity.

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); The distance between one end of the connection line with respect to the second direction (Y) and the second edge (102) corresponding thereto is smaller than the distance between any bus bar (220) electrically connected thereto and the second edge (102); The distance between one end of the bus bar (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), the auxiliary connection line (340) passing through the central area (110) along the second direction (Y) and electrically connected to the side connection lines (320) on both sides; the auxiliary connection line (340) is electrically connected to the current collecting fine 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 fine 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 battery string, wherein the battery 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.

Images