Back contact battery, preparation method thereof and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a back contact battery and a preparation method thereof, and a photovoltaic module, and the back contact battery comprises a battery body of which the back surface comprises a first edge region, a central region and a second edge region which are sequentially arranged along a first direction; the first fine grid and the second fine grid are positioned in the central region and are alternately arranged along a second direction; the edge bus bar extends along the second direction, is positioned in the first edge region or the second edge region, and is connected with the plurality of first or second fine grids; the edge bonding pad is located on the portion, close to the first edge area or the second edge area, of at least one fine grid and electrically connected with the edge bus bar, and the fine grid is one of the first fine grid and the second fine grid; one end of the connecting section is connected with one side, close to the edge bus bar, of the edge bonding pad or connected with one of the two opposite sides of the edge bonding pad in the second direction, the other end of the connecting section is connected with the edge bonding pad or one fine grid, and at least the photoelectric conversion efficiency of the back contact battery can be improved.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the photovoltaic field, and in particular to a back-contact battery and a preparation method thereof, and a photovoltaic module. Background Art

[0002] At present, with the gradual depletion of fossil energy, photovoltaic cells are becoming more and more widely used as a new energy alternative. Photovoltaic cells are devices that convert sunlight into electrical energy. Photovoltaic cells use the principle of photovoltaics to generate carriers, and then use electrodes to lead the carriers out, thereby facilitating the effective use of electrical energy.

[0003] The factors that affect the photoelectric conversion efficiency and yield of photovoltaic cells mainly include the following two aspects: one is optical loss, which includes but is not limited to shading loss, carrier recombination loss in the substrate, carrier recombination loss in the highly doped film layer, and refractive loss in the film layer; the other is electrical loss, which includes but is not limited to the resistance loss of the material itself, the contact loss of the electrode, the contact loss between the soldering ribbon and the photovoltaic cell, and the cold solder joint between the soldering ribbon and the photovoltaic cell.

[0004] Therefore, there is an urgent need in the art to provide a photovoltaic cell and a photovoltaic module that can reduce electrical loss and / or optical loss, thereby improving the photoelectric conversion efficiency of the corresponding photovoltaic cell and the yield of the photovoltaic module. Summary of the invention

[0005] The embodiments of the present disclosure provide a back-contact cell and a method for preparing the same, and a photovoltaic module, which are at least beneficial to improving the photoelectric conversion efficiency of the back-contact cell.

[0006] According to some embodiments of the present disclosure, on one hand, an embodiment of the present disclosure provides a back-contact battery, comprising: a battery body, the back side of the battery body comprising a first edge region, a center region, and a second edge region arranged in sequence along a first direction; a first fine grid and a second fine grid located in the center region and alternately arranged along a second direction; an edge bus bar extending along the second direction, located in the first edge region or the second edge region, and connected to one of the plurality of the first fine grids or the plurality of the second fine grids; an edge pad, located on a portion of at least one fine grid close to the first edge region or the second edge region, and electrically connected to the edge bus bar, the fine grid being one of the first fine grid and the second fine grid; a connecting section, the orthographic projection of the connecting section on the back side being wavy; wherein one end of the connecting section is connected to a side of the edge pad close to the edge bus bar, or to one of the two opposite sides of the edge pad along the second direction; the other end of the connecting section is connected to the edge pad or to one of the fine grids.

[0007] In some embodiments, the connecting section includes: at least one first connecting section, the first connecting section includes a plurality of first bending sections connected in sequence along the first direction, one end of the first connecting section opposite to each other along the first direction is connected to the edge bus bar, and the other end is connected to the edge pad; and / or, at least one second connecting section, the second connecting section includes a plurality of second bending sections connected in sequence along the second direction, one end of the second connecting section opposite to each other along the second direction is connected to the edge pad, and the other end is connected to one of the fine grids.

[0008] In some embodiments, the edge pad includes a first pad and a second pad, the first pad is electrically connected to the first fine gate and electrically insulated from the second fine gate, the second pad is electrically connected to the second fine gate and electrically insulated from the first fine gate; the second connection segment connected to the first pad is also connected to at least one of the first fine gates; the second connection segment connected to the second pad is also connected to at least one of the second fine gates.

[0009] In some embodiments, the back-contact battery further includes: a thickened edge portion extending along the first direction, one end of the thickened edge portion being connected to the edge bus bar, and the other end being connected to the edge pad, and along the second direction, a first width of the thickened edge portion being greater than a second width of the fine grid connected to the edge pad; and / or, at least one first connecting segment is respectively provided on two opposite sides of the thickened edge portion along the second direction, and a first connecting segment is directly opposite to a fine grid electrically insulated from the edge pad along the first direction.

[0010] In some embodiments, the battery body includes a substrate and a passivation layer located on a surface of the substrate, and the connecting segment and the fine grid are partially embedded in the passivation layer.

[0011] In some embodiments, a single edge pad is electrically connected to one of the first fine grid and the second fine grid, and is electrically insulated from the other; at least one fine grid electrically insulated from the edge pad near the edge pad is disconnected, and the edge pad or the connecting section is located at the disconnection of the fine grid; the photovoltaic cell also includes: a connecting grid line, one end of the connecting grid line opposite to each other along the second direction is connected to the disconnected fine grid, and the other end is connected to another fine grid adjacent to the disconnected fine grid along the second direction.

[0012] According to some embodiments of the present disclosure, on the other hand, the embodiments of the present disclosure further provide a method for preparing a back-contact battery, comprising: providing a battery body, the back side of the battery body comprising a first edge region, a center region, and a second edge region sequentially arranged along a first direction; forming a first fine grid, a second fine grid, and a connecting segment on the center region, wherein the first fine grid and at least a portion of the connecting segment are formed using the same preparation process, and / or the second fine grid and at least a portion of the connecting segment are formed using the same preparation process, the first fine grid and the second fine grid are alternately arranged along a second direction, and the orthographic projection shape of the connecting segment on the back side is wavy; in the first edge region or the second fine grid, a first fine grid is formed; and a second fine grid is formed; and ... An edge bus bar is formed on the second edge area, the edge bus bar extends along the second direction and is connected to one of the plurality of first fine grids or the plurality of second fine grids; an edge pad is formed, the edge pad is located on a portion of at least one fine grid close to the first edge area or the second edge area, and is electrically connected to the edge bus bar, the fine grid is one of the first fine grid and the second fine grid; wherein one end of the connecting section is connected to a side of the edge pad close to the edge bus bar, or to one of the two opposite sides of the edge pad along the second direction; the other end of the connecting section is connected to the edge pad or to one of the fine grids.

[0013] In some embodiments, the step of forming the connecting segment includes: providing a first screen, printing paste on the first screen to form at least one first connecting segment, the first connecting segment includes a plurality of first bending segments connected in sequence along the first direction, one end of the first connecting segment opposite to each other along the first direction is connected to the edge bus bar, and the other end is connected to the edge pad; and / or providing a second screen, printing paste on the second screen to form at least one second connecting segment, the second connecting segment includes a plurality of second bending segments connected in sequence along the second direction, one end of the second connecting segment opposite to each other along the second direction is connected to the edge pad, and the other end is connected to one of the fine grids; the connecting segments include at least one first connecting segment and / or at least one second connecting segment.

[0014] In some embodiments, the step of providing the first screen includes: providing the first screen having at least one first opening, the first opening being used to form a first connecting section, the first opening including a plurality of first sub-openings connected in sequence along the first direction, and two adjacent first sub-openings are arranged up and down along the second direction; and / or, the step of providing the second screen includes: providing the second screen having at least one second opening, the second opening being used to form a second connecting section, the second opening including a plurality of second sub-openings connected in sequence along the second direction, and two adjacent second sub-openings are arranged left and right along the first direction.

[0015] According to some embodiments of the present disclosure, on the other hand, the embodiments of the present disclosure further provide a photovoltaic module, including: a cell string, formed by connecting a plurality of back-contact cells as described in any of the above items, or formed by connecting a plurality of back-contact cells formed by any of the preparation methods described in any of the above items; a packaging film for covering the surface of the cell string; and a cover plate for covering the surface of the packaging film facing away from the cell string.

[0016] The technical solution provided by the embodiments of the present disclosure has at least the following advantages:

[0017] On the one hand, the connection segment is used to transfer the current from the edge bus bar or fine grid to the edge pad, which is conducive to adding more current flow paths on the back side with the help of the connection segment, so as to ultimately improve the current collection effect of the edge pad; on the other hand, the positive projection shape of the connection segment on the back side is designed to be wavy, which increases the cross-sectional area of ​​the connection segment itself, as well as the contact area where the connection segment contacts the edge pad and the edge bus bar or fine grid, compared with the positive projection shape of the grid line similar to a straight line, thereby improving the transmission efficiency of the connection segment for current, and further reducing the transmission resistance in the process of current transmission from the edge bus bar or fine grid to the edge pad. In this way, the combined effect of multiple aspects is conducive to improving the current collection efficiency of the back contact battery, so as to improve its photoelectric conversion efficiency.

[0018] In addition, on the one hand, the design of the connection section on the back side in a wavy shape can reduce the risk of the connection section being broken by force, and can also reduce the risk of disconnection between the connection section and the edge pad, and reduce the risk of disconnection between the connection section and the edge bus bar or fine grid compared to the grid line whose orthographic projection shape is similar to a straight line; on the other hand, the edge bus bar does not have an edge pad and the two are electrically connected, which is conducive to avoiding the subsequent welding strip connected to the edge pad from being located in the first edge area or the second edge area, thereby avoiding the edge cracking problem caused to the back contact battery. In this way, multiple aspects work together to improve the yield of the back contact battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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 disclosure 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.

[0020] Figure 1A partial top view schematic diagram of a back contact battery provided by an embodiment of the present disclosure;

[0021] Figure 2 A partial top view schematic diagram corresponding to a single edge pad in a back contact battery provided by an embodiment of the present disclosure;

[0022] Figure 3 Another partial top view schematic diagram corresponding to a single edge pad in a back contact battery provided by an embodiment of the present disclosure;

[0023] Figure 4 A schematic top view of a first connecting section in a back contact battery provided in an embodiment of the present disclosure;

[0024] Figure 5 A schematic top view of a second connecting segment in a back contact battery provided in an embodiment of the present disclosure;

[0025] Figure 6 for Figure 3 A partial cross-sectional schematic diagram of the back contact battery shown along the first cross-sectional direction AA1;

[0026] Figure 7 A schematic top view of connecting grid lines in a back contact battery provided by an embodiment of the present disclosure;

[0027] Figure 8 A partial top view schematic diagram of a first screen provided in a method for preparing a back-contact battery provided in another embodiment of the present disclosure;

[0028] Fig. 9 A partial top view schematic diagram of a second screen provided in a method for preparing a back-contact battery provided in another embodiment of the present disclosure;

[0029] Fig.10 A schematic diagram of a partial three-dimensional structure of a photovoltaic assembly provided by another embodiment of the present disclosure;

[0030] Fig.11 for Fig.10 A schematic diagram of a partial cross-sectional structure of a photovoltaic assembly along a second cross-sectional direction BB1 is shown. DETAILED DESCRIPTION

[0031] As known from the background technology, the photoelectric conversion efficiency of photovoltaic cells needs to be improved.

[0032] The present disclosure provides a back-contact cell and a preparation method thereof, and a photovoltaic module. In the back-contact cell, on the one hand, a connecting section is used to transmit current from an edge bus bar or a fine grid to an edge pad, which is beneficial to add more current flow paths on the back side with the help of the connecting section, so as to ultimately improve the current collection effect of the edge pad; on the other hand, the positive projection shape of the connecting section on the back side is designed to be wavy, which increases the cross-sectional area of ​​the connecting section itself and the contact area of ​​the connecting section with the edge pad and the edge bus bar or the fine grid compared to the positive projection shape of the grid line similar to a straight line, thereby improving the transmission efficiency of the connecting section for current, and further reducing the transmission resistance in the process of current transmission from the edge bus bar or the fine grid to the edge pad. In this way, multiple aspects work together to improve the current collection efficiency of the back-contact cell, so as to improve its photoelectric conversion efficiency. In addition, on the other hand, the design of the connection section on the back side has a wavy shape in the orthographic projection. Compared with the grid line whose orthographic projection shape is similar to a straight line, it can not only reduce the risk of the connection section being broken by force, but also reduce the risk of disconnection between the connection section and the edge pad, and reduce the risk of disconnection between the connection section and the edge bus bar or the fine grid; on the other hand, there is no edge pad on the edge bus bar and the two are electrically connected, which is conducive to avoiding the subsequent welding strip connected to the edge pad from being located in the first edge area or the second edge area, thereby avoiding the edge cracking problem caused to the back contact battery. In this way, multiple aspects work together to improve the yield of the back contact battery.

[0033] In the description of the embodiments of the present disclosure, 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 disclosure, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0034] 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 disclosure. The appearance of the phrase in various places 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.

[0035] In the description of the embodiments of the present disclosure, 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 may 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.

[0036] In the description of the embodiments of the present disclosure, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0037] In the description of the embodiments of the present disclosure, the orientations or positional relationships indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description. They do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure.

[0038] In the description of the embodiments of the present disclosure, 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 disclosure can be understood according to the specific circumstances.

[0039] In the accompanying drawings corresponding to the embodiments of the present disclosure, the thickness and area of ​​the layers are magnified for better understanding and ease of description. When describing a component (such as a layer, a film, a region or a substrate) on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may be present between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component 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 partial edge of the entire surface.

[0040] In the description of the embodiments of the present disclosure, when a component "includes" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, a film, a region, or a plate is referred to as being "on / located on" another component, it may be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may exist in between. In addition, when a component such as a layer, a film, a region, a plate, etc. is "directly located on" another component, or when a component such as a layer, a film, a region, a plate, etc. is located on the surface of another component, it means that no other components are located in between.

[0041] 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.

[0042] 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 embodiments of 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 embodiments of the present disclosure can be implemented.

[0043] An embodiment of the present disclosure provides a back-contact battery, which will be described in detail below with reference to the accompanying drawings.

[0044] refer to Figure 1 , Figure 2 or Figure 3The back contact battery comprises: a battery body 100, wherein the back side 110 of the battery body 100 comprises a first edge region 120, a central region 130 and a second edge region 140 arranged in sequence along a first direction X; first fine grids 111 and second fine grids 121 located in the central region 130 and arranged alternately along a second direction Y; an edge bus bar 102 extending along the second direction Y, located in the first edge region 120 or the second edge region 140, and connected to one of the plurality of first fine grids 111 or the plurality of second fine grids 121; an edge pad 103 located at least one of the fine grids 10 1 is on a portion close to the first edge area 120 or the second edge area 140, and is electrically connected to the edge bus bar 102, the fine grid 101 is one of the first fine grid 111 and the second fine grid 121; a connecting section 104, the positive projection shape of the connecting section 104 on the back side 110 is wavy; wherein one end of the connecting section 104 is connected to a side of the edge pad 103 close to the edge bus bar 102, or is connected to one side of the two opposite sides of the edge pad 103 along the second direction Y; the other end of the connecting section 104 is connected to the edge pad 103 or is connected to a fine grid 101.

[0045] in, Figure 1 A partial top view schematic diagram of a back contact battery provided by an embodiment of the present disclosure; Figure 2 A partial top view schematic diagram corresponding to a single edge pad in a back contact battery provided by an embodiment of the present disclosure; Figure 3 Another partial top view of a single edge pad in a back contact cell provided in an embodiment of the present disclosure. It should be noted that, in order to distinguish the first fine grid 111 from the second fine grid 121, Figure 1 In the figure, the first fine grid 111 is indicated by a solid line, and the second fine grid 121 is indicated by a dotted line. Figure 2 and Figure 3 In the drawing, the first fine gate 111 and the second fine gate 121 are drawn using different filling methods, and Figure 3 The edge pad 103 is drawn in a perspective drawing manner.

[0046] It is worth noting that the edge pad 103 is located on a portion of at least one fine grid 101 close to the first edge region 120 or the second edge region 140, and is electrically connected to the edge bus bar 102. In other words, the edge bus bar 102 does not have an edge pad, and the edge bus bar 102 collects the current on one of the multiple first fine grids 111 or the multiple second fine grids 121 connected thereto, and further transmits it to the edge pad 103 electrically connected thereto but not located in the edge region. In the subsequent stage of preparing photovoltaic modules using photovoltaic cells, the welding strip is set on the edge pad 103 to collect the current collected by the edge bus bar 102, so that the welding strip can be located in the center region instead of the edge region with the edge pad 103, so as to avoid the edge crack problem caused to the back contact cell when the welding strip is located in the edge region, that is, the first edge region 120 or the second edge region 140, and is conducive to improving the yield of the photovoltaic module formed subsequently based on the improvement of the back contact cell.

[0047] Moreover, in order to improve the collection effect of the edge pad 103 on the current on the fine grid 101 or the current on the edge bus bar 102, on the one hand, the current is transmitted from the edge bus bar 102 or the fine grid 101 to the edge pad 103 by using the connecting section 104, which is conducive to adding more current flow paths on the back side 110 with the help of the connecting section 104, so as to ultimately improve the current collection effect of the edge pad 103; on the other hand, the positive projection shape of the connecting section 104 on the back side 110 is designed to be wavy, compared with the fine grid 101 whose positive projection shape is similar to a straight line, not only the cross-sectional area of ​​the connecting section 104 itself is larger, but also It is beneficial to reduce the transmission resistance of the connecting section 104 itself, improve the transmission efficiency of the connecting section 104 for current, and the contact area where the connecting section 104 contacts the edge pad 103 is also larger, and the contact area where the connecting section 104 contacts the edge bus bar 102 or the fine grid 101 is also larger, so as to reduce the contact resistance between the connecting section 104 and the edge pad 103, and reduce the contact resistance between the connecting section 104 and the edge bus bar 102 or the fine grid 101, so as to further reduce the transmission resistance in the process of current transmission from the edge bus bar 102 or the fine grid 101 to the edge pad 103. In this way, the combined effect of multiple aspects is beneficial to improve the current collection efficiency of the back contact cell, so as to improve its photoelectric conversion efficiency.

[0048] In addition, the orthographic projection shape of the connecting section 104 on the back surface 110 is designed to be wavy. Compared with the fine grid 101 whose orthographic projection shape is similar to a straight line, it can not only reduce the risk of the connecting section 104 being broken by force due to the larger cross-sectional area of ​​the connecting section 104, but also reduce the risk of disconnection between the connecting section 104 and the edge pad 103 due to the larger contact area between the connecting section 104 and the edge pad 103, and reduce the risk of disconnection between the connecting section 104 and the edge bus bar 102 or the fine grid 101 due to the larger contact area between the connecting section 104 and the edge bus bar 102 or the fine grid 101. In this way, the combined effect of multiple aspects is conducive to improving the yield of the back contact battery.

[0049] It should be noted that the battery body 100 can be a back contact battery with a main grid or a back contact battery without a main grid. Regardless of whether the battery body 100 is provided with a main grid, the current on the fine grid 101 needs to be collected and utilized. Based on this, a pad or a welding point, and a welding strip electrically connecting a plurality of pads or welding points will be designed on at least a part of the fine grid 101, wherein the pad or welding point is located in the central area 130. Based on the fact that the fine grid 101 can be any one of the first fine grid 111 and the second fine grid 121, the welding strip can also be divided into two categories, one of which is electrically connected to the first fine grid 111 and electrically insulated from the second fine grid 121 to collect the current on the first fine grid 111, and the other of which is electrically connected to the second fine grid 121 and electrically insulated from the first fine grid 111 to collect the current on the second fine grid 121. For any welding strip, it is only electrically connected to one of the plurality of first fine grids 111 and the plurality of second fine grids 121.

[0050] The battery body 100 is described in detail below as a back-contact battery with a busbar and a back-contact battery without a busbar.

[0051] In some embodiments, reference Figure 1 The battery body 100 may be a back-contact battery with a main grid, and the back-contact battery may further include: first main grids 115 and second main grids 125 arranged alternately along the first direction X, the first main grids 115 are used to collect currents on all first fine grids 111, and the second main grids 125 are used to collect currents on all second fine grids 121. Based on this, the second fine grids 121 are disconnected at the first main grid 115, and the first fine grids 111 are disconnected at the second main grid 125. The disconnected portion of the second fine grid 121 is used for the first main grid 115 to extend along the second direction Y and be electrically connected to the plurality of first fine grids 111, and the disconnected portion of the first fine grid 111 is used for the second main grid 125 to extend along the second direction Y and be electrically connected to the plurality of second fine grids 121.

[0052] It should be noted that Figure 1 The pad in contact with the first main grid 115 or the second main grid 125 is used as the central pad 133, and Figure 1 The edge pads 103 and the center pad 133 are drawn using different filling methods.

[0053] In other embodiments, the battery body may be a back-contact battery without a main grid, and the back-contact battery may further include: first welding strips and second welding strips arranged alternately along a first direction, the first welding strips being used to collect currents on all first fine grids, and the second welding strips being used to collect currents on all second fine grids. Based on this, the second fine grids are disconnected at the first welding strips, and the first fine grids are disconnected at the second welding strips, and the disconnected portion of the second fine grids is used for the first welding strips to extend along the second direction and be electrically connected to the plurality of first fine grids, and the disconnected portion of the first fine grids is used for the second welding strips to extend along the second direction and be electrically connected to the plurality of second fine grids.

[0054] It is worth emphasizing that in the above two embodiments, the main grid or welding strip is located in the central area 130. For the thin grid 101 disconnected by the main grid or welding strip closest to the first edge area 120, in addition to designing the edge bus bar 102 on the first edge area 120 to collect the current on the disconnected thin grid 101 located closest to the first edge area 120, the edge pad 103 is also designed to be located in the central area 130 instead of the first edge area 120, so as to avoid the subsequent welding strip connected to the edge pad 103 being located in the first edge area 120, so as to avoid the problem of stress concentration at the first edge area 120 causing the battery body 100 to be broken during the welding of the welding strip to the edge pad 103. The main grid includes a first main grid 115 and a second main grid 125, and the welding strip includes a first welding strip and a second welding strip.

[0055] Similarly, for the fine grid 101 that is disconnected by the main grid or welding strip closest to the second edge area 140, in addition to designing an edge bus bar 102 on the second edge area 140 to collect the current on a section of the disconnected fine grid 101 located closest to the second edge area 140, the edge welding pad 103 is also designed to be located in the central area 130 rather than the second edge area 140, so as to avoid the subsequent welding strip connecting the edge welding pad 103 being located in the second edge area 140, so as to avoid the problem of stress concentration in the second edge area 140 causing fragments of the battery body 100 during the process of welding the welding strip to the edge welding pad 103.

[0056] In some cases, if the sum of the first main grid 115 and the second main grid 125 is an even number, or the sum of the first welding strip and the second welding strip is an even number, then Figure 1, one of the first main grid 115 and the second main grid 125 is closest to the first edge region 120, and the other is closest to the second edge region 140, or one of the first welding strip and the second welding strip is closest to the first edge region 120, and the other is closest to the second edge region 140. In this way, the edge bus bar 102 located in the first edge region 120 and the edge bus bar 102 located in the second edge region 140 collect currents on the fine grids 101 of different polarities. It should be noted that Figure 1 Only a single first busbar 115 or a single second busbar 125 is illustrated. In actual applications, there is no limitation on the number of first busbars and the number of single second busbars 125 designed on the back side 110 .

[0057] In other cases, combined with reference Figure 2 and Figure 3 , if the sum of the first main grid and the second main grid is an odd number, or the sum of the first welding strip and the second welding strip is an odd number, then the main grid closest to the first edge area 120 and the main grid closest to the second edge area 140 are of the same polarity, that is, the main grid closest to the first edge area 120 and the main grid closest to the second edge area 140 are both the first main grid or both the second main grid, or, the welding strips closest to the first edge area 120 and the welding strips closest to the second edge area 140 are of the same category, that is, the welding strips closest to the first edge area 120 and the welding strips closest to the second edge area 140 are both the first welding strip or both the second welding strip. In this way, the edge bus bar 102 located in the first edge area 120 and the edge bus bar 102 located in the second edge area 140 collect the current on the fine grid 101 of the same polarity, for example, Figure 2 and Figure 3 The edge bus bars 102 shown are used to collect the current on the first fine grid 111 .

[0058] The embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings.

[0059] In some embodiments, reference Figure 1 or Figure 3 ,as well as Figure 4 , Figure 4 A top view schematic diagram of the first connecting section in a back-contact battery provided for an embodiment of the present disclosure, the connecting section 104 may include: at least one first connecting section 114, the first connecting section 114 includes a plurality of first bending sections 114a connected in sequence along a first direction X, one end of the first connecting section 114 at two opposite ends along the first direction X is connected to the edge bus bar 102, and the other end is connected to the edge pad 103.

[0060] In this way, it is beneficial to use the first connecting section 114 to transmit current from the edge bus bar 102 to the edge pad 103. Moreover, designing the first connecting section 114 to include multiple first bending sections 114a is not only beneficial to increase the cross-sectional area of ​​the first connecting section 114 itself, but also beneficial to increase the contact area between the first connecting section 114 and the edge pad 103, and increase the contact area between the first connecting section 114 and the edge bus bar 102, so as to improve the current transmission efficiency and reduce the risk of interruption of the current transmission path.

[0061] In addition, the edge pad 103 is not only connected to at least one fine gate 101, but also blocks the fine gate 101 of the opposite polarity that is electrically insulated from the edge pad 103 from extending further to the edge area. Designing the first connecting section 114 in the area where the fine gate 101 of the opposite polarity cannot extend due to the blocking of the edge pad 103 is also beneficial to improving the utilization rate of the back side 110, for example, increasing the distribution density of the fine gate 101 per unit area of ​​the back side 110.

[0062] It should be noted that Figure 4 In the figure, a plurality of first bending segments 114 a in a single first connecting segment 114 are divided by thicker dotted lines.

[0063] also, Figure 1 and Figure 3 In the example, the edge pad 103 is only located on one fine grid 101 and blocks two fine grids 101 of opposite polarity, and two first connection segments 114 are designed to correspond to the two blocked fine grids 101 of opposite polarity. In practical applications, the edge pad may be only located on one fine grid and only blocks one fine grid of opposite polarity, and one first connection segment may be designed to correspond to the blocked fine grid of opposite polarity; or the edge pad may be located on multiple fine grids and only blocks multiple fine grids of opposite polarity, and multiple first connection segments may be designed to correspond to the blocked fine grids of opposite polarity. In one embodiment of the present disclosure, there is no limitation on the number of fine grids covered by a single edge pad, and the number may be adjusted according to the specific size of the edge pad.

[0064] In some embodiments, reference Figure 2 or Figure 3 ,as well as Figure 5 , Figure 5 A top view schematic diagram of a second connecting segment in a back-contact battery provided for an embodiment of the present disclosure, the connecting segment 104 may include: at least one second connecting segment 124, the second connecting segment 124 includes a plurality of second bending segments 124a sequentially connected along a second direction Y, one end of the second connecting segment 124 at two opposite ends along the second direction Y is connected to an edge pad 103, and the other end is connected to a fine grid 101.

[0065] In this way, it is beneficial to use the connecting section 104 to transmit current from a certain fine grid 101 close to the edge pad 103 to the edge pad 103. Moreover, designing the second connecting section 124 to include multiple second bending sections 124a is not only beneficial to increase the cross-sectional area of ​​the second connecting section 124 itself, but also beneficial to increase the contact area between the second connecting section 124 and the edge pad 103, and increase the contact area between the second connecting section 124 and a certain fine grid 101, so as to improve the current transmission efficiency and reduce the risk of interruption of the current transmission path.

[0066] In addition, when the welding ribbon is welded to the edge pad 103, due to the influence of welding temperature and welding stress, the fine grid 101 located near the edge pad 103 is easily affected and has the risk of breaking. After the fine grid 101 breaks, the current on a part of the fine grid 101 cannot be collected by the edge bus bar 102. Based on this, the second connecting section 124 connecting the edge pad 103 and a fine grid 101 close to the edge pad 103 is designed, which is conducive to directly transmitting the current on the fine grid 101 to the edge pad 103 through the second connecting section 124, avoiding the current loss after the fine grid 101 breaks, and no need to collect the current based on the edge bus bar 102 and then transmit it to the edge pad 103.

[0067] It should be noted that Figure 5 In the figure, a plurality of second bending segments 124 a in a single second connecting segment 124 are divided by thicker dotted lines, and in order to clearly illustrate the second bending segment 124 a, the second connecting segment 124 is drawn in a white filling manner.

[0068] In some cases, reference Figure 2 The second connecting section 124 can also be located under the edge pad 103 and connected to the fine gate 101 covered by the edge pad 103 to ensure the connection strength between the edge pad 103 and the fine gate 101 and the connection strength between the edge pad 103 and the second connecting section 124, further reducing the risk that the current on some fine gates 101 cannot be transmitted to the edge pad 103.

[0069] In some cases, reference Figure 3 Two second connection segments 124 spaced apart along the second direction Y may be provided between a single edge pad 103 and a certain fine grid 101, which is also beneficial to further ensure that the current on the fine grid 101 can be transmitted to the edge pad 103, so as to effectively avoid current loss after the fine grid 101 is broken.

[0070] In some other embodiments, reference Figure 3The connecting section 104 may include: at least one first connecting section 114, the first connecting section 114 includes a plurality of first bending sections 114a sequentially connected along the first direction X, one end of the first connecting section 114 opposite to each other in the first direction X is connected to the edge bus bar 102, and the other end is connected to the edge pad 103; at least one second connecting section 124, the second connecting section 124 includes a plurality of second bending sections 124a sequentially connected along the second direction Y, one end of the second connecting section 124 opposite to each other in the second direction Y is connected to the edge pad 103, and the other end is connected to a fine grid 101.

[0071] In some examples, along the second direction Y, the ratio of the width of the first connecting segment 114 to the width of the fine gate 101 can be 1-2, for example, the ratio of the width of the first connecting segment 114 to the width of the fine gate 101 can be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8 or 1.9, etc.

[0072] In some examples, the ratio of the width of the second connecting segment 124 in the first direction X to the width of the fine gate 101 in the second direction Y may be 1 to 2. For example, the ratio of the width of the second connecting segment 124 in the first direction X to the width of the fine gate 101 in the second direction Y may be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8 or 1.9, etc.

[0073] In some embodiments, reference Figure 1 , the edge pad 103 may include a first pad 113 and a second pad 123, the first pad 113 is electrically connected to the first fine gate 111 and is electrically insulated from the second fine gate 121, and the second pad 123 is electrically connected to the second fine gate 121 and is electrically insulated from the first fine gate 111. Figure 1 and Figure 3 The second connection segment 124 connected to the first pad 113 is also connected to at least one first fine grid 111 ; the second connection segment 124 connected to the second pad 123 is also connected to at least one second fine grid 121 .

[0074] It is worth noting that the second connecting segment 124 may also cover at least one fine grid 101 of the same polarity which is close to the edge pad 103 and has a distance therefrom. Figure 3 In the example, the second connection segment 124 covers one fine grid 101 of the same polarity close to the edge pad 103 and having a spacing therefrom. In practical applications, based on the size variation of the edge pad 103, the number of fine grids 101 of the same polarity close to the edge pad 103 and having a spacing therefrom covered by the second connection segment 124 is not limited, for example, it may also be 2, 3 or 4.

[0075] In some embodiments, reference Figures 1 to 3 The back contact battery may also include: an edge thickening portion 106 extending along the first direction X, one end of the edge thickening portion 106 is connected to the edge bus bar 102, and the other end is connected to the edge pad 103, and along the second direction Y, the first width of the edge thickening portion 106 is greater than the second width of the fine grid 101 connected to the edge pad 103.

[0076] It is worth noting that, compared with the current collected on the fine grid 101 directly connected to the edge pad 103, the edge bus bar 102 collects the current on multiple fine grids 101, so the amount of current collected on the edge bus bar 102 is larger. Based on this, the first width of the edge thickening portion 106 is designed to be greater than the second width of the fine grid 101 connected to the edge pad 103, so that the cross-sectional area of ​​the edge thickening portion 106 itself is larger and its own transmission resistance is smaller, which is more matched with the amount of current on the edge bus bar 102, which is conducive to improving the transmission efficiency of the edge thickening portion 106 for current, thereby further improving the photoelectric conversion efficiency of the back contact battery.

[0077] Moreover, based on the large cross-sectional area of ​​the edge thickening portion 106, it is beneficial to increase the contact area between the edge thickening portion 106 and the edge bus bar 102, and increase the contact area between the edge thickening portion 106 and the edge pad 103, thereby improving the connection strength between the edge thickening portion 106 and the edge bus bar 102, and the connection strength between the edge thickening portion 106 and the edge pad 103, so as to ensure the electrical connection between the edge bus bar 102 and the edge pad 103.

[0078] In some embodiments, reference Figure 1 or Figure 3 At least one first connection segment 114 is respectively disposed on two opposite sides of the edge thickening portion 106 along the second direction Y, and a first connection segment 114 is directly opposite to a fine grid 101 electrically insulated from the edge pad 103 along the first direction X.

[0079] It is worth noting that, based on the design of the edge pad 103, not only the thin gate 101 of the opposite polarity electrically insulated from the edge pad 103 is blocked from further extending to the edge area, but also the thin gate 101 of the same polarity directly connected to the edge pad 103 is blocked from further extending to the edge area. Designing the edge thickening portion 106 in the area where the thin gate 101 of the same polarity cannot extend due to the blocking of the edge pad 103 is also conducive to improving the utilization rate of the back surface 110. Moreover, not only does a first connecting section 114 face a thin gate 101 electrically insulated from the edge pad 103 along the first direction X, but the edge thickening portion 106 also faces the thin gate 101 of the same polarity blocked by the edge pad 103 along the first direction X.

[0080] It should be noted that Figure 1 and Figure 3In the figure, a single edge pad 103 blocks one fine grid 101 of the same polarity and two fine grids 101 of opposite polarities, and then one edge thickening portion 106 and two first connecting segments 114 are designed to be connected to the edge pad 103 as an example. In actual applications, based on the specific position of the edge pad on the back side and the specific size of the edge pad, there is no restriction on the number of fine grids of the same polarity and the number of fine grids of opposite polarities blocked by a single edge pad. The number of designed edge thickening portions can be adjusted according to the number of fine grids of the same polarity blocked by the edge pad, and the number of designed first connecting segments can be adjusted according to the number of fine grids of opposite polarities blocked by the edge pad.

[0081] In some examples, along the second direction Y, the ratio of the width of the edge thickening portion 106 to the width of the fine gate 101 can be 5-30. For example, the ratio of the width of the edge thickening portion 106 to the width of the fine gate 101 can be 6, 8, 10, 12, 15, 16, 20, 24, 25 or 28, etc.

[0082] In some embodiments, reference Figure 6 , Figure 6 for Figure 3 The illustrated schematic diagram is a partial cross-sectional view of a back-contact battery along a first cross-sectional direction AA1 . The battery body 100 may include a substrate 150 and a passivation layer 160 located on a surface of the substrate 150 . The connecting segment 104 and the fine grid 101 are partially embedded in the passivation layer 160 .

[0083] In this way, the connecting section 104 can not only be used to transmit the current on the edge bus bar 102 or the fine grid 101 to the edge pad 103, but the connecting section 104 can also collect the photogenerated carriers generated in the substrate 150 like the fine grid 101, thereby improving the collection efficiency of the photogenerated carriers in the substrate 150. Furthermore, the orthographic projection shape of the connecting section 104 on the back surface 110 is designed to be wavy, which is beneficial to increase the contact area between the connecting section 104 and the back surface 110 compared to the fine grid 101 whose orthographic projection shape is similar to a straight line, so that the connecting section 104 can collect photogenerated carriers in a larger area on the back surface 110, thereby further improving the collection efficiency of the photogenerated carriers in the substrate 150, so as to improve the photoelectric conversion efficiency of the back contact cell.

[0084] In some cases, the material of the connecting segment 104 may be the same as that of the fine grid 101. For example, the slurry of the connecting segment 104 is the same as that of the fine grid 101, and both the connecting segment 104 and the fine grid 101 are made of a burn-through slurry, so that the connecting segment 104 also penetrates the passivation layer 160. In this way, the connecting segment 104 is not only used to transmit the current on the edge bus bar 102 or the fine grid 101 to the edge pad 103, but the connecting segment 104 can also collect the photogenerated carriers in the substrate 150 by itself, thereby increasing the collection path of the photogenerated carriers and improving the photoelectric conversion efficiency of the back contact cell.

[0085] In some cases, the passivation layer 160 may be a single-layer film structure or a stacked-layer film structure, and the material of the passivation layer 160 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride oxide, titanium oxide, hafnium oxide or aluminum oxide.

[0086] In some cases, the substrate 150 has a first surface and a second surface that are arranged opposite to each other, and the first surface has a suede structure. The suede structure can increase the internal reflection of the incident light to reduce optical loss and improve the photoelectric conversion efficiency of the back contact cell.

[0087] In some examples, the first surface has a front surface field (FSF), and the conductivity type of the doped ions is the same as that of the doped ions of the substrate 150, and the field passivation effect is used to reduce the surface minority carrier concentration, thereby reducing the surface recombination rate, and at the same time, the series resistance can be reduced, and the current transmission capacity can be improved. The first surface also has a first passivation layer and a first anti-reflection layer, the first passivation layer is located on the surface of the front surface field, and the first anti-reflection layer is located on the side of the first passivation layer away from the substrate 150. It should be noted that the substrate 150 does not necessarily include a front surface field, a first passivation layer, and a first anti-reflection layer.

[0088] In some examples, the second surface has alternately arranged first and second regions, the first region is one of the P region or the N region, the second region is the other of the P region or the N region, and there is a gap between the P region and the N region; in other examples, there may not be a gap between the P region and the N region, and there is an insulating film layer between the P region and the N region to achieve insulation between the P region and the N region, thereby achieving insulation between the first fine gate 111 and the second fine gate 121. The first fine gate 111 may be located on one of the first region and the second region, and the second fine gate 121 may be located on the other of the first region and the second region.

[0089] In some examples, the spacer region gap may be flush with the P region and the N region, that is, the substrate 150 is not etched, and the P region and the N region are insulated by some isolating film layers, and the isolating film layers may be passivation film layers or intrinsic semiconductor layers; in other examples, the spacer region gap may be lower than the P region and the spacer region gap may be lower than the N region, and the spacer region gap has a groove, which extends from the second surface toward the first surface, and the groove is used to achieve automatic isolation between regions of different conductive types, which can eliminate the leakage caused by the formation of PN junctions between heavily doped P regions and N regions in the back contact battery, thereby affecting the battery efficiency.

[0090] In some examples, the surface of the spacer gap may be a polished surface structure or a velvet surface structure.

[0091] In some examples, the P region and the N region may have a tunneling silicon oxide layer and a doped polysilicon layer, respectively, wherein the P region has a P-type doped polysilicon layer and the N region has an N-type doped polysilicon layer. In other examples, the P region and the N region may have an intrinsic amorphous silicon layer, a doped amorphous silicon layer and a transparent conductive layer, respectively, wherein the P region has a P-type doped amorphous silicon layer and the N region has an N-type doped amorphous silicon layer.

[0092] In some embodiments, a second passivation layer and a second anti-reflection layer are disposed on the P region, the N region and the gap region, and the first fine gate 111 and the second fine gate 121 are located on the second anti-reflection layer and embedded in the second passivation layer. It should be noted that the second passivation layer is the aforementioned passivation layer 106 .

[0093] In other embodiments, the material of the connecting section may be the same as that of the first main grid. For example, the slurry of the connecting section is the same as that of the first main grid, and the connecting section and the first main grid are both made of non-burn-through slurry. The connecting section is located on the surface of the passivation layer but is not embedded in the passivation layer. In this way, it is not necessary to layout the first area and the second area on the surface of the substrate below the connecting section to prevent the connection section from being in electrical contact with the doping area of ​​the other polarity, which may cause a short circuit. In addition, the connecting section may not cause damage to the passivation layer, so that the integrity of the film layer of the passivation layer is ensured, thereby improving the passivation effect of the passivation layer on the substrate, which is beneficial to reducing the optical loss of the back contact battery, thereby improving the photoelectric conversion efficiency of the back contact battery. In addition, since the non-burn-through slurry does not have too much glass powder to damage the PN junction, it can effectively reduce metal composites, increase the open circuit voltage of the back contact battery, and improve the conversion efficiency of the back contact battery.

[0094] It should be noted that the conventional paste may include a mixture of metal powder, glass powder and an organic carrier. Non-burn-through paste refers to a paste that contains less glass powder than the conventional paste, has a weak burn-through ability during the sintering process, and does not need or cannot burn through the passivation layer. Burn-through paste refers to a paste that has a strong burn-through ability during the sintering process and can burn through the passivation layer.

[0095] In practical applications, the connecting segments may also be some film layers or conductive wires having conductive materials, and only need to transmit the current on the edge bus bar 102 or the fine grid 101 to the edge pad 103 .

[0096] In some embodiments, reference Figure 2 or Figure 3 , a single edge pad 103 is electrically connected to one of the first fine gate 111 and the second fine gate 121 and is electrically insulated from the other; at least one fine gate 101 electrically insulated from the edge pad 103 near the edge pad 103 is disconnected. In some cases, referring to Figure 2, the edge pad 103 is located at the disconnection point of the fine gate 101; in other cases, refer to Figure 3 , the connecting section 104 is located at the disconnection point of the fine gate 101.

[0097] Continue to refer Figure 2 or Figure 3 The photovoltaic cell may further include: a connecting grid line 107, wherein one end of the connecting grid line 107 at two opposite ends along the second direction Y is connected to the disconnected fine grid 101, and the other end is connected to another fine grid 101 adjacent to the disconnected fine grid 101 along the second direction Y. In this way, it is beneficial to connect the fine grid 101 of the opposite polarity disconnected by the edge pad 103 or the connecting section 104 to another adjacent fine grid 101 of the opposite polarity by means of the connecting grid line 107, so that the current on the fine grid 101 of the opposite polarity disconnected by the edge pad 103 or the connecting section 104 can also be collected, so as to further improve the collection efficiency of the photogenerated carriers in the substrate 150, so as to improve the photoelectric conversion efficiency of the back contact cell.

[0098] In one case, reference Figure 7 , Figure 7 A schematic top view of a connecting grid line in a back-contact battery provided in an embodiment of the present disclosure, the connecting grid line 107 may include a plurality of third bending sections 117 sequentially connected along the second direction Y. For example, the positive projection shape of the connecting grid line 107 on the back side 110 is wavy. In this way, not only the cross-sectional area of ​​the connecting grid line 107 itself is larger, which is conducive to reducing the transmission resistance of the connecting grid line 107 itself and improving the transmission efficiency of the connecting grid line 107 for current, but also the contact area at the contact point between the connecting grid line 107 and the fine grid 101 is larger, which is conducive to reducing the contact resistance between the connecting grid line 107 and the fine grid 101, and reducing the contact resistance between the connecting grid line 107 and the fine grid 101.

[0099] In addition, the orthographic projection shape of the connecting gate line 107 on the back side 110 is wavy, which can reduce the risk of the connecting gate line 107 being broken due to stress based on the connecting gate line 107 having a larger cross-sectional area, and can also reduce the risk of disconnection between the connecting gate line 107 and the fine gate 101 based on the larger contact area between the connecting gate line 107 and the fine gate 101.

[0100] It should be noted that Figure 7 In the figure, a plurality of third bending sections 117 in a single connecting gate line 107 are divided by thicker dotted lines.

[0101] In summary, on the one hand, using the connection section 104 to transmit the current from the edge bus bar 102 or the fine grid 101 to the edge pad 103 is conducive to adding more current flow paths on the back side 110 with the help of the connection section 104, so as to ultimately improve the current collection effect of the edge pad 103; on the other hand, the positive projection shape of the connection section 104 on the back side 110 is designed to be wavy, which increases the cross-sectional area of ​​the connection section 104 itself and the contact area of ​​the connection section 104 at the contact point with the edge pad 103 and the contact point with the edge bus bar 102 or the fine grid 101 compared to the fine grid 101 with a straight line shape, thereby improving the transmission efficiency of the connection section 104 for current, and further reducing the transmission resistance in the process of current transmission from the edge bus bar 102 or the fine grid 101 to the edge pad 103. In this way, the combined effect of multiple aspects is conducive to improving the current collection efficiency of the back contact cell, so as to improve its photoelectric conversion efficiency.

[0102] In addition, on the one hand, the design of the connection section 104 on the back side 110 is wavy in shape, which can reduce the risk of the connection section 104 being broken by force, and can also reduce the risk of disconnection between the connection section 104 and the edge pad 103, and reduce the risk of disconnection between the connection section 104 and the edge bus bar 102 or the fine grid 101. On the other hand, the edge bus bar 102 does not have an edge pad and the two are electrically connected, which is conducive to avoiding the subsequent solder strip connected to the edge pad 103 from being located in the first edge area 120 or the second edge area 140, thereby avoiding the edge cracking problem caused to the back contact battery. In this way, multiple aspects work together to improve the yield of the back contact battery.

[0103] According to some embodiments of the present disclosure, another aspect of the present disclosure also provides a method for preparing a back-contact battery, which is used to prepare the back-contact battery provided by the aforementioned embodiment. The following will describe in detail the method for preparing a back-contact battery provided by another embodiment of the present disclosure in conjunction with the accompanying drawings. It should be noted that the parts that are the same or corresponding to the aforementioned embodiments will not be repeated here.

[0104] Combined with reference Figures 1 to 9The preparation method of the back contact battery may include the following steps: providing a battery body 100, wherein the back side 110 of the battery body 100 includes a first edge region 120, a central region 130, and a second edge region 140 sequentially arranged along a first direction X; forming a first fine grid 111, a second fine grid 121, and a connecting segment 104 on the central region 130, wherein the first fine grid 111 and at least a portion of the connecting segment 104 are formed by the same preparation process, and / or the second fine grid 121 and at least a portion of the connecting segment 104 are formed by the same preparation process, the first fine grid 111 and the second fine grid 121 are alternately arranged along a second direction Y, and the orthographic projection shape of the connecting segment 104 on the back side 110 is wavy; in the first edge region 120 or the second edge region An edge bus bar 102 is formed on 140, and the edge bus bar 102 extends along the second direction Y and is connected to one of the multiple first fine grids 111 or the multiple second fine grids 121; an edge pad 103 is formed, and the edge pad 103 is located on a portion of at least one fine grid 101 close to the first edge area 120 or the second edge area 140, and is electrically connected to the edge bus bar 102, and the fine grid 101 is one of the first fine grid 111 and the second fine grid 121; wherein one end of the connecting section 104 is connected to a side of the edge pad 103 close to the edge bus bar 102, or to one of the two opposite sides of the edge pad 103 along the second direction Y; the other end of the connecting section 104 is connected to the edge pad 103 or to a fine grid 101.

[0105] It is worth emphasizing that part of the connecting segment 104 can be prepared simultaneously with the step of preparing the first fine gate 111 and / or part of the connecting segment 104 can be prepared simultaneously with the step of preparing the second fine gate 121 , which is conducive to simplifying the preparation process of forming the connecting segment 104 .

[0106] in, Figure 8 A partial top view schematic diagram of a first screen provided in a method for preparing a back-contact battery provided in another embodiment of the present disclosure; Fig. 9 A partial top view schematically showing a second screen provided in a method for preparing a back-contact battery according to another embodiment of the present disclosure.

[0107] In some embodiments, in conjunction with reference Figure 8 and Figure 1 ,or Figure 8 and Figure 3The step of forming the connection section 104 may include: providing a first screen 108, printing paste on the first screen 108 to form at least one first connection section 114, the first connection section 114 includes a plurality of first bending sections 114a sequentially connected along the first direction X, one end of the first connection section 114 opposite to the other end along the first direction X is connected to the edge bus bar 102, and the other end is connected to the edge pad 103. In this way, it is beneficial to make the orthographic projection shape of the first connection section 114 on the back surface 110 to be wavy by virtue of the plurality of first bending sections 114a sequentially connected along the first direction X.

[0108] In one embodiment, the step of providing a first screen 108 may include: providing a first screen 108 having at least one first opening 118, wherein a first opening 118 is used to form a first connecting section 114, and the first opening 118 includes a plurality of first sub-openings 128 connected in sequence along a first direction X, and two adjacent first sub-openings 128 are arranged up and down along a second direction Y.

[0109] It is worth noting that the first connecting segment 114 can be prepared together with the fine grid 101, so the first screen 108 can also have a third opening for forming the fine grid 101. The third opening is generally a long narrow opening extending along the first direction X. When the first opening 118 and the third opening are simultaneously prepared on the first screen 108, due to the influence of the process, the first opening 118 is more easily made into a plurality of first sub-openings 128 with a very short length in the first direction X, and two adjacent first sub-openings 128 are designed to be arranged up and down along the second direction Y. Therefore, the first connecting segment 114 with a wavy shape in the orthographic projection on the back side 110 can be formed with the help of the first opening 118.

[0110] In some embodiments, in conjunction with reference Fig. 9 and Figure 2 ,or Fig. 9 and Figure 3 The step of forming the connecting segment 104 may include: providing a second screen 109, printing paste on the second screen 109 to form at least one second connecting segment 124, the second connecting segment 124 includes a plurality of second bending segments 124a sequentially connected along the second direction Y, one end of the two opposite ends of the second connecting segment 124 along the second direction Y is connected to the edge pad 103, and the other end is connected to a fine grid 101. In this way, it is beneficial to make the orthographic projection shape of the second connecting segment 124 on the back surface 110 to be wavy by virtue of the plurality of second bending segments 124a sequentially connected along the second direction Y.

[0111] In one embodiment, the step of providing a second screen 109 may include: providing a second screen 109 having at least one second opening 119, wherein a second opening 119 is used to form a second connecting section 124, and the second opening 119 includes a plurality of second sub-openings 129 connected in sequence along a second direction Y, and two adjacent second sub-openings 129 are arranged left and right along the first direction X.

[0112] It is worth noting that the second connecting segment 124 can be prepared together with the fine grid 101, so the second screen 109 can also have a third opening for forming the fine grid 101. The third opening is generally a long narrow opening extending along the first direction X. When the second opening 119 and the third opening are simultaneously prepared on the second screen 109, due to the influence of the process, the second opening 119 is more easily made into a plurality of second sub-openings 129 with a very short length in the first direction X, and two adjacent second sub-openings 129 are designed to be arranged left and right along the first direction X. Therefore, the second connecting segment 124 with a wavy shape in the orthographic projection on the back side 110 can be formed with the help of the second opening 119.

[0113] It should be noted that, in the same back contact battery, the connecting segment 104 may include only at least one first connecting segment 114 , or include only at least one second connecting segment 124 , or include at least one first connecting segment 114 and at least one second connecting segment 124 .

[0114] In some cases, in the same back-contact cell, multiple connecting segments 104 may all be electrically connected to the fine grid 101 of the same polarity, for example, multiple connecting segments 104 may all be electrically connected to the first fine grid 111 or to the second fine grid 121; in other cases, in the same back-contact cell, some connecting segments 104 are electrically connected to the first fine grid 111, and other connecting segments 104 are electrically connected to the second fine grid 121. In either case, the first fine grid 111, the second fine grid 121 and the connecting segments 104 may all be formed in the same preparation method, and the first opening 118 on the first screen 108 and the second opening 119 on the second screen 109 may be integrated into the same screen, and the screen also has a third opening for preparing the fine grid 101.

[0115] To sum up, in the preparation method of the back-contact battery provided in another embodiment of the present disclosure, the connecting segment 104 and the fine grid 01 can be formed simultaneously, which is not only conducive to simplifying the preparation process of forming the connecting segment 104, but also conducive to forming the connecting segment 104 with a wavy shape in the positive projection shape on the back side 110.

[0116] According to some embodiments of the present disclosure, another aspect of the embodiments of the present disclosure further provides a photovoltaic module, which is formed by connecting a plurality of back-contact cells provided by the aforementioned embodiments, or by connecting a plurality of back-contact cells formed by the preparation methods provided by the aforementioned embodiments. The photovoltaic module provided by another embodiment of the present disclosure will be described below in conjunction with the accompanying drawings. It should be noted that the parts that are the same or corresponding to the aforementioned embodiments will not be described in detail here.

[0117] Combined with reference Fig.10 , Fig.11 as well as Figures 1 to 3 The photovoltaic module includes: a battery string, which is formed by connecting multiple back-contact batteries provided by the aforementioned embodiments, or by connecting multiple back-contact batteries formed by the preparation methods provided by the aforementioned embodiments; a packaging film 41, which is used to cover the surface of the battery string; and a cover plate 42, which is used to cover the surface of the packaging film 41 away from the battery string.

[0118] in, Fig.10 A partial three-dimensional structural schematic diagram of a photovoltaic assembly provided by another embodiment of the present disclosure, Fig.11 for Fig.10 A schematic diagram of a partial cross-sectional structure of a photovoltaic assembly along a second cross-sectional direction BB1 is shown.

[0119] In some embodiments, the back contact cell 10 is a BC cell (Back Contact), and BC cells include but are not limited to IBC cells (Interdigitated Back Contact), HBC cells (Heterojunction Back Contact), TBC cells (TOPCon Back Contact, referring to cross-passivated back contact cells) or HPBC cells (Hybrid Passivated Back Contact, composite passivated back contact cells), etc. In addition, the back contact cell 10 is electrically connected in the form of a whole piece or multiple pieces to form a plurality of cell strings, and the plurality of cell strings are electrically connected in series and / or in parallel. The back contact cell 10 can be a whole cell or a sliced ​​cell, and a sliced ​​cell refers to a cell formed by a complete whole cell through a cutting process.

[0120] In some embodiments, reference Fig.10 or Fig.11 Multiple back contact cells 10 can be electrically connected via conductive tapes 43 . Fig.10 and Fig.11Only one positional relationship between the back contact batteries 10 is illustrated. The back contact batteries 10 may also have gate lines of different polarities facing the same side, that is, the gate lines of multiple adjacent back contact batteries 10 are arranged in the order of the first polarity, the second polarity, and the first polarity, respectively. Then the conductive tape 43 connects the same side of two adjacent back contact batteries 10.

[0121] In some embodiments, the encapsulation film 41 includes a first encapsulation layer and a second encapsulation layer, wherein the first encapsulation layer covers one of the front side or the back side of the back contact battery 10, and the second encapsulation layer covers the other of the front side or the back side of the back contact battery 10. Specifically, at least one of the first encapsulation layer or the second encapsulation layer may be an organic encapsulation film such as a polyvinyl butyral (PVB) film, an ethylene-vinyl acetate copolymer (EVA) film, a polyethylene octene co-elastomer (POE) film, or a polyethylene terephthalate (PET) film, or at least one of the first encapsulation layer or the second encapsulation layer may also be an EP film, an EPE film, or a PVP film. Among them, EP film refers to a co-extruded film composed of stacked EVA film and POE film, EPE film refers to a co-extruded film formed by stacking EVA film + POE film + EVA film in sequence, and PVP film refers to a co-extruded film formed by stacking POE film + EVA film + POE film. The co-extruded film can be prepared by sequentially extruding one or more raw materials onto another already manufactured film during the film processing process, or bonding different types of already manufactured films together.

[0122] In some cases, there is a boundary between the first encapsulation layer and the second encapsulation layer before lamination. After the lamination process, the photovoltaic module is formed and there is no longer the concept of the first encapsulation layer and the second encapsulation layer, that is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0123] In some embodiments, the cover plate 42 may be a glass cover plate, a plastic cover plate or the like with a light-transmitting function. Specifically, the surface of the cover plate 42 facing the encapsulation film 41 may be a concave-convex surface or a velvet surface including a plurality of convex structures, thereby increasing the utilization rate of the incident light. The cover plate 42 includes a first cover plate and a second cover plate, the first cover plate is opposite to the first encapsulation layer, and the second cover plate is opposite to the second encapsulation layer.

[0124] In some cases, when the back contact battery 10 is a battery with a main grid, the surface of the back contact battery 10 has a plurality of main grids arranged at intervals along a first direction and a plurality of fine grids arranged at intervals along a second direction, and the main grid includes a main grid connection line and a pad located on the main grid connection line. In the process of constructing a battery string using the back contact battery 10, the conductive tape 43 is electrically connected to at least one main grid on each of the two adjacent back contact batteries 10.

[0125] In other cases, when the back-contact battery 10 is a main-grid-free battery, the surface of the back-contact battery 10 has a plurality of fine grids arranged at intervals along the third direction Z. In the process of constructing a battery string using the back-contact battery 10, the conductive tape 43 is electrically connected to the plurality of fine grids on each of the two adjacent back-contact batteries 10.

[0126] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for implementing the present disclosure, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of the embodiments 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 embodiments of the present disclosure, so the protection scope of the embodiments of the present disclosure shall be based on the scope defined in the claims.

Claims

1. A back contact battery, characterized in that: include: A battery body, wherein the back side of the battery body comprises a first edge area, a center area, and a second edge area sequentially arranged along a first direction; First fine grids and second fine grids located in the central area and arranged alternately along a second direction; an edge bus bar extending along the second direction, located in the first edge region or the second edge region, and connected to one of the plurality of first fine grids or the plurality of second fine grids; an edge pad, located on a portion of at least one fine grid close to the first edge region or the second edge region, and electrically connected to the edge bus bar, the fine grid being one of the first fine grid and the second fine grid; A connecting section, wherein the orthographic projection of the connecting section on the back surface is wavy; One end of the connecting section is connected to one side of the edge pad close to the edge bus bar, or to one side of two opposite sides of the edge pad along the second direction; the other end of the connecting section is connected to the edge pad or to one of the fine grids.

2. The back contact cell according to claim 1, characterized in that: The connecting section comprises: at least one first connecting segment, the first connecting segment comprising a plurality of first bending segments sequentially connected along the first direction, one end of two opposite ends of the first connecting segment along the first direction being connected to the edge bus bar, and the other end being connected to the edge pad; and / or, At least one second connecting segment, the second connecting segment includes a plurality of second bending segments sequentially connected along the second direction, one end of the two opposite ends of the second connecting segment along the second direction is connected to the edge pad, and the other end is connected to one of the fine grids.

3. The back contact battery according to claim 2, characterized in that: The edge pad includes a first pad and a second pad, the first pad is electrically connected to the first fine grid and is electrically insulated from the second fine grid, and the second pad is electrically connected to the second fine grid and is electrically insulated from the first fine grid; The second connection segment connected to the first pad is also connected to at least one of the first fine grids; The second connection segment connected to the second pad is also connected to at least one of the second fine grids.

4. The back contact cell according to claim 2, characterized in that: Also includes: an edge thickening portion extending along the first direction, one end of the edge thickening portion being connected to the edge bus bar and the other end being connected to the edge pad, and along the second direction, a first width of the edge thickening portion being greater than a second width of the fine grid connected to the edge pad; and / or, At least one first connection segment is respectively disposed on two opposite sides of the edge thickening portion along the second direction, and one of the first connection segments is directly opposite to one of the fine grids electrically insulated from the edge pad along the first direction.

5. The back contact cell according to any one of claims 1 to 4, characterized in that The battery body includes a substrate and a passivation layer located on the surface of the substrate, and the connecting segment and the fine grid are partially embedded in the passivation layer.

6. The back contact cell according to any one of claims 1 to 4, characterized in that A single edge pad is electrically connected to one of the first fine grid and the second fine grid, and is electrically insulated from the other; at least one of the fine grids electrically insulated from the edge pad and close to the edge pad is disconnected, and the edge pad or the connecting section is located at the disconnection of the fine grid; The back contact battery further comprises: A connecting gate line, wherein one end of two opposite ends of the connecting gate line along the second direction is connected to the disconnected fine gate, and the other end is connected to another fine gate adjacent to the disconnected fine gate along the second direction.

7. A method for preparing a back contact battery, characterized in that: include: Providing a battery body, wherein the back side of the battery body comprises a first edge area, a center area, and a second edge area sequentially arranged along a first direction; forming a first fine grid, a second fine grid and a connecting segment on the central area, wherein the first fine grid and at least a part of the connecting segment are formed by the same manufacturing process, and / or the second fine grid and at least a part of the connecting segment are formed by the same manufacturing process, the first fine grid and the second fine grid are alternately arranged along the second direction, and the orthographic projection of the connecting segment on the back surface is wavy; forming an edge bus bar on the first edge region or the second edge region, wherein the edge bus bar extends along the second direction and is connected to one of the plurality of first fine grids or the plurality of second fine grids; forming an edge pad, the edge pad being located on a portion of at least one fine grid close to the first edge region or the second edge region and being electrically connected to the edge bus bar, the fine grid being one of the first fine grid and the second fine grid; One end of the connecting section is connected to one side of the edge pad close to the edge bus bar, or to one side of two opposite sides of the edge pad along the second direction; the other end of the connecting section is connected to the edge pad or to one of the fine grids.

8. The preparation method according to claim 7, characterized in that: The steps of forming the connecting section include: Providing a first screen, printing paste on the first screen to form at least one first connecting section, the first connecting section includes a plurality of first bending sections sequentially connected along the first direction, one end of the first connecting section opposite to each other along the first direction is connected to the edge bus bar, and the other end is connected to the edge pad; and / or providing a second screen, printing paste on the second screen to form at least one second connecting section, the second connecting section includes a plurality of second bending sections sequentially connected along the second direction, one end of the second connecting section opposite to each other along the second direction is connected to the edge pad, and the other end is connected to one of the fine grids; The connecting segments include at least one of the first connecting segments and / or at least one of the second connecting segments.

9. The preparation method according to claim 8, characterized in that: The step of providing the first screen includes: providing the first screen having at least one first opening, wherein the first opening is used to form a first connecting section, wherein the first opening includes a plurality of first sub-openings sequentially connected along the first direction, and two adjacent first sub-openings are arranged vertically along the second direction; and / or, The step of providing the second screen includes: providing the second screen having at least one second opening, wherein the second opening is used to form a second connecting section, wherein the second opening includes a plurality of second sub-openings connected in sequence along the second direction, and two adjacent second sub-openings are arranged left and right along the first direction.

10. A photovoltaic module, characterized in that: include: A battery string formed by connecting a plurality of back-contact batteries according to any one of claims 1 to 6, or by connecting a plurality of back-contact batteries formed by the preparation method according to any one of claims 7 to 9; A packaging film, used to cover the surface of the battery string; The cover plate is used to cover the surface of the packaging film facing away from the battery string.

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