Back contact cell, back contact laminated cell and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a back contact battery, a back contact laminated battery and a photovoltaic module, and the back contact battery comprises a battery substrate which is provided with two opposite edge regions along a first direction, two opposite edge regions along a second direction, and a central region located between the two edge regions; the first fine grid and the second fine grid are positioned on the battery substrate and are alternately arranged along a second direction; the bonding pad is positioned in the edge region; at least the edge connecting line located in the edge area and the bonding pad closest to the edge connecting line are electrically connected with the same-polarity grid line; the first connecting part is electrically connected with the edge connecting line and the bonding pad closest to the edge connecting line; the second connecting part is electrically connected with the opposite grid lines disconnected by the bonding pad; the edge connecting line comprises two thickened parts and a main body part positioned between the two thickened parts; the thickened parts are electrically connected with the same-polarity grid lines positioned in the edge area and the same-polarity grid lines which are positioned in the central area and are disconnected by the second connecting part; and one of the first fine grid and the second fine grid is the same-polarity grid line, and the other one is the opposite-polarity grid line, so that the electrical performance of the back contact battery is improved at least.

Description

Technical Field

[0001] The present disclosure relates to the field of photovoltaics, and particularly to a back contact battery, a back contact tandem battery, and a photovoltaic module. Background Art

[0002] As fossil energy is gradually depleted, photovoltaic cells, as a new energy alternative, are being used more and more widely. A photovoltaic cell is a device that converts the light energy of the sun into electrical energy. The photovoltaic cell uses the photovoltaic effect to generate carriers, and then uses grid lines to lead out the carriers, so as to facilitate the effective utilization of electrical energy. The grid lines of the photovoltaic cell play an important role in collecting and transmitting electrons. When a photovoltaic module is assembled using multiple photovoltaic cells, pads and / or solder joints are often provided on the grid lines, and then the grid lines of adjacent photovoltaic cells are electrically connected by using a welding wire to electrically contact the pads and / or solder joints.

[0003] To further avoid the shading of the front surface of the photovoltaic cell by the grid lines, the research on IBC cells (Interdigitated Back Contact cells), that is, back contact cells, has become more and more in-depth.

[0004] However, in IBC cells, in order to improve the collection efficiency of carriers, with the change of the electrical connection relationship between multiple grid lines and pads and / or solder joints, there may be a large difference in the current density collected in different regions of the back contact battery, which affects the overall electrical performance of the back contact battery. For example, hot spot effects are likely to occur in local areas, reducing the photoelectric conversion efficiency of the back contact battery. Summary of the Invention

[0005] Embodiments of the present disclosure provide a back contact battery, a back contact tandem battery, and a photovoltaic module, which are at least beneficial to improving the electrical performance of the back contact battery.

[0006] According to some embodiments of the present disclosure, on the one hand, an embodiment of the present disclosure provides a back-contact battery, including: a battery substrate having two edge regions opposite to each other in a first direction, two edge regions opposite to each other in a second direction, and a central region located between the two edge regions; a first fine grid and a second fine grid arranged alternately on the battery substrate in the second direction; pads located in the edge regions, and a single pad is electrically connected to at least one grid line of the same polarity; an edge connection line located at least in the edge region, and both the edge connection line and the pad closest to the edge connection line are electrically connected to the grid line of the same polarity; a first connection portion extending in the first direction, electrically connecting the edge connection line and the pad closest to the edge connection line; at least one grid line of the opposite polarity located on a side of the first connection portion close to the central region is disconnected by the pad; a second connection portion extending in the second direction, electrically connecting the grid line of the opposite polarity disconnected by the pad, and at least one grid line of the same polarity is disconnected by the second connection portion; wherein the edge connection line includes two thickened portions opposite to each other in the second direction, and a main body portion located between the two thickened portions, the thickened portion is electrically connected to the grid line of the same polarity located in the edge region, and is electrically connected to the grid line of the same polarity disconnected by the second connection portion located in the central region; in the first direction, the width of the thickened portion is greater than the width of the main body portion; one of the first fine grid and the second fine grid is the grid line of the same polarity, and the other is the grid line of the opposite polarity.

[0007] In some embodiments, the back-contact battery further includes: a first auxiliary line electrically connected not only to the pad but also to at least one grid line of the same polarity located on a side of the pad away from the central region; a second auxiliary line electrically connected not only to the pad but also to at least one grid line of the same polarity located on a side of the pad close to the central region.

[0008] In some embodiments, in the first direction, the width of the first auxiliary line is greater than the width of the second auxiliary line.

[0009] In some embodiments, the battery substrate has a first welding region and a second welding region located between the two edge regions and arranged alternately in the first direction; the back-contact battery further includes: in the second direction, a plurality of solder joints arranged at intervals between adjacent pads, a first fine grid located in a region where the first welding region coincides with the central region is electrically connected to a solder joint, and a second fine grid located in a region where the second welding region coincides with the central region is electrically connected to a solder joint.

[0010] In some embodiments, along the second direction, there is a second fine grid between two adjacent solder joints in the same first welding area; along the second direction, there is a first fine grid between two adjacent solder joints in the same second welding area.

[0011] In some embodiments, along the second direction, the width of the first connection part is greater than the width of the same-sex grid line.

[0012] In some embodiments, at least one of the opposite-sex grid lines on the side of the first connection part away from the central area is disconnected by the pad; the back-contact battery further includes: a third connection part extending along the second direction, electrically connecting the opposite-sex grid lines that are disconnected by the pad and on the side of the first connection part away from the central area, and at least one of the same-sex grid lines is disconnected by the third connection part.

[0013] In some embodiments, the battery substrate has a plurality of welding areas located between the two edge areas and arranged at intervals along the first direction; the back-contact battery further includes: a busbar part, located in the area where a partial number of the welding areas coincide with the edge area, the busbar part electrically connecting a plurality of the same-sex grid lines on the side of the pad away from the central area, and there is at least one welding area between the welding area having the busbar part and the edge area.

[0014] In some embodiments, the edge connection line further includes: an edge part located in the edge area and extending along the first direction, one end of the edge part is electrically connected to one end of the thickened part, and the main body part is electrically connected to the other end of the thickened part; the edge part is in contact connection with the busbar part electrically connecting one of the first fine grid and the second fine grid, and is disconnected at the busbar part electrically connecting the other of the first fine grid and the second fine grid.

[0015] According to some embodiments of the present disclosure, on the other hand, the present disclosure embodiments further provide a back-contact stacked battery, including: a bottom battery, the bottom battery is the back-contact battery as described in any one of the above; a top battery, the top battery is located on one side of the bottom battery.

[0016] According to some embodiments of the present disclosure, on yet another aspect, the present disclosure embodiments further provide a photovoltaic module, including: a battery string, which is formed by connecting a plurality of the back-contact batteries as described in any one of the above, or formed by connecting a plurality of the back-contact stacked batteries as described in any one of the above; an encapsulation glue film, used to cover the surface of the battery string; a cover plate, used to cover the surface of the encapsulation glue film facing away from the battery string.

[0017] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages: First, both the edge connection line and the pad closest to the edge connection line are electrically connected to the same-sex grid line. Even if the part of the same-sex grid line facing the solder strip has poor electrical connection, the carriers in the part of the same-sex grid line close to the edge area can be collected by means of the edge connection line, the first connection part, and the pad, which is beneficial to improving the collection efficiency of carriers in the back-contact battery. Moreover, by means of the edge connection line, the circulation path of carriers in the same-sex grid line can be increased, promoting the uniform circulation of current in the back-contact battery to improve the overall electrical performance of the back-contact battery, such as current density homogenization, thereby enhancing the thermal spot resistance performance of the back-contact battery.

[0018] Furthermore, it is designed that the thickened part of the edge connection line is electrically connected not only to the same-sex grid line located in the edge area but also to the same-sex grid line disconnected by the second connection part located in the central area. In other words, the thickened part of the edge connection line not only extends to the part connected to the first connection part but also further extends in the direction close to the central area. In this way, on the basis of improving the transmission efficiency of carriers in the thickened part by virtue of the larger width of the thickened part in the first direction, it is beneficial to improve the collection efficiency of carriers in the same-sex grid line disconnected by the second connection part by means of the thickened part facing at least part of the area of the first connection part in the first direction. For example, it can reduce the carrier loss during the process of the carriers in the same-sex grid line disconnected by the second connection part being transmitted to the solder strip through the edge connection line, the first connection part, and the pad, which is beneficial to reducing the difference in carrier density between the same-sex grid line disconnected by the second connection part and the same-sex grid line in other areas, so as to further promote the uniform circulation of current in the back-contact battery, thereby further improving the overall electrical performance of the back-contact battery. Description of the Drawings

[0019] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments unless otherwise stated. The figures in the drawings do not constitute a proportional limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the following-described drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is a first partial enlarged top view schematic diagram of a back-contact battery provided by an embodiment of the present disclosure; Figure 2 It is a second partial enlarged top view schematic diagram of a back-contact battery provided by an embodiment of the present disclosure; Figure 3 It is a third partial enlarged top view schematic diagram of a back-contact battery provided by an embodiment of the present disclosure; Figure 4 The fourth partial enlarged top view schematic diagram of the back contact battery provided by an embodiment of the present disclosure; Figure 5 An enlarged top view schematic diagram of the back contact battery provided by an embodiment of the present disclosure; Figure 6 Another enlarged top view schematic diagram of the back contact battery provided by an embodiment of the present disclosure; Figure 7 A combined top view schematic diagram of the pad and the bus bar in the back contact battery provided by an embodiment of the present disclosure; Figure 8 A partial cross-sectional schematic diagram of the back contact stacked battery provided by another embodiment of the present disclosure; Figure 9 A partial three-dimensional schematic diagram of the battery string in the photovoltaic module provided by still another embodiment of the present disclosure; Figure 10 A partial cross-sectional schematic diagram of the photovoltaic module provided by still another embodiment of the present disclosure.

[0021] Explanation of reference numerals: 100, battery substrate; 110, edge region; 120, border region; 130, central region; 45, welding region; 140, first welding region; 150, second welding region; 101, first fine grid; 102, second fine grid; 103, pad; 104, edge connection line; 114, thickened portion; 124, main body portion; 134, border portion; 105, first connection portion; 106, second connection portion; 117, first auxiliary line; 127, second auxiliary line; 108, solder joint; 109, third connection portion; 119, bus bar; 129, bottom cell; 139, top cell; 40, back contact battery; 41, encapsulation adhesive film; 42, cover plate; 43, conductive strip. Detailed implementation manners

[0022] As can be seen from the background art, the electrical performance of the back contact battery needs to be improved.

[0023] Embodiments of the present disclosure provide a back-contact battery, a back-contact stacked battery, and a photovoltaic module. In the back-contact battery, an edge connection line and the pad closest to the edge connection line are both electrically connected to the same-sex grid line. Even if the part of the same-sex grid line facing the solder strip has poor electrical connection, the carriers in the part of the same-sex grid line close to the edge region can be collected by means of the edge connection line, the first connection part, and the pad, which is beneficial to improving the collection efficiency of carriers in the back-contact battery. Moreover, by means of the edge connection line, the circulation path of carriers in the same-sex grid line can be increased, promoting the uniform circulation of current in the back-contact battery, so as to improve the overall electrical performance of the back-contact battery, such as current density homogenization, thereby enhancing the anti-hot spot performance of the back-contact battery. Further, it is designed that the thickened part of the edge connection line is electrically connected not only to the same-sex grid line located in the edge region, but also to the same-sex grid line disconnected by the second connection part located in the central region. In other words, the thickened part of the edge connection line not only extends to the part connected to the first connection part, but also further extends in the direction closer to the central region. Thus, on the basis of improving the transmission efficiency of carriers in the thickened part by means of the larger width of the thickened part in the first direction, by means of the thickened part facing at least part of the region of the first connection part in the first direction, it is beneficial to improve the collection efficiency of carriers in the same-sex grid line disconnected by the second connection part by the edge connection line. For example, the carrier loss in the process of the carriers in the same-sex grid line disconnected by the second connection part being transmitted to the solder strip through the edge connection line, the first connection part, and the pad can be reduced, which is beneficial to reducing the difference in carrier density between the same-sex grid line disconnected by the second connection part and the same-sex grid line in other regions, so as to further promote the uniform circulation of current in the back-contact battery, thereby further improving the overall electrical performance of the back-contact battery.

[0024] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order, or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "a plurality" is more than two, unless otherwise clearly and specifically defined.

[0025] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of the present disclosure. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0026] In the description of the embodiments of the present disclosure, the term "and / or" is merely a relationship describing associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: the existence of A, the simultaneous existence of A and B, and the existence of B. Additionally, the character " / " in this text generally represents an "or" relationship between the associated objects before and after.

[0027] In the description of the embodiments of the present disclosure, the term "plurality" refers to two or more (including two). Similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces).

[0028] In the description of the embodiments of the present disclosure, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present disclosure 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. Therefore, it should not be construed as a limitation on the embodiments of the present disclosure.

[0029] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "coupling", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside 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 specific circumstances.

[0030] In the corresponding drawings of the embodiments of the present disclosure, for better understanding and convenience of description, the thickness and area of the layers are enlarged. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component 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 "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 on a partial edge of the entire surface.

[0031] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise stated, other components are not excluded, and other components may further be included. In addition, when a component such as a layer, film, region, or 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 therebetween), or there may be other components therebetween. In addition, when a component such as a layer, film, region, or plate is "directly located on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located therebetween.

[0032] The terms used in the description of the various embodiments herein are for the purpose of describing particular embodiments only and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is also intended to include the plural form unless the context clearly indicates otherwise. Among them, the component includes components such as layers, films, regions, or plates.

[0033] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are provided to help readers 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 still be implemented.

[0034] An embodiment of the present disclosure provides a back-contact battery, and the back-contact battery provided by an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0035] Reference Figures 1 to 6, the back-contact battery includes: a battery substrate 100 having two edge regions 110 opposite to each other along a first direction X, two edge regions 120 opposite to each other along a second direction Y, and a central region 130 located between the two edge regions 120; a first fine grid 101 and a second fine grid 102 arranged alternately along the second direction Y on the battery substrate 100; pads 103 located in the edge regions 120, and a single pad 103 is electrically connected to at least one grid line of the same polarity; an edge connection line 104 located at least in the edge region 110, and both the edge connection line 104 and the pad 103 closest to the edge connection line 104 are electrically connected to grid lines of the same polarity; a first connection portion 105 extending along the first direction X, electrically connecting the edge connection line 104 and the pad 103 closest to the edge connection line 104; at least one grid line of opposite polarity located on one side of the first connection portion 105 close to the central region 130 is disconnected by the pad 103; a second connection portion 106 extending along the second direction Y, electrically connecting the grid lines of opposite polarity disconnected by the pad 103, and at least one grid line of the same polarity is disconnected by the second connection portion 106; wherein, the edge connection line 104 includes two thickened portions 114 opposite to each other along the second direction Y, and a main body portion 124 located between the two thickened portions 114, the thickened portion 114 is electrically connected to the grid lines of the same polarity located in the edge region 120, and is electrically connected to the grid lines of the same polarity disconnected by the second connection portion 106 located in the central region 130; along the first direction X, the width of the thickened portion 114 is greater than the width of the main body portion 124; one of the first fine grid 101 and the second fine grid 102 is a grid line of the same polarity, and the other is a grid line of opposite polarity.

[0036] It should be noted that Figure 1 is the first partially enlarged top view schematic diagram of the back-contact battery provided by an embodiment of the present disclosure; Figure 2 is the second partially enlarged top view schematic diagram of the back-contact battery provided by an embodiment of the present disclosure; Figure 3 is the third partially enlarged top view schematic diagram of the back-contact battery provided by an embodiment of the present disclosure; Figure 4 is the fourth partially enlarged top view schematic diagram of the back-contact battery provided by an embodiment of the present disclosure; Figure 5 is an enlarged top view schematic diagram of the back-contact battery provided by an embodiment of the present disclosure; Figure 6 is another enlarged top view schematic diagram of the back-contact battery provided by an embodiment of the present disclosure.

[0037] In addition, first, Figures 1 to 6 the first fine grid 101 is schematically shown by a thinner solid line, and the second fine grid 102 is schematically shown by a thicker solid line in all of them.

[0038] Second, Figures 1 to 4Take, for example, the case where for a certain edge connection line 104, the same-sex grid lines are the first thin grids 101 and the opposite-sex grid lines are the second thin grids 102. In practical applications, for a certain edge connection line, it can also be that the same-sex grid lines are the first thin grids and the opposite-sex grid lines are the second thin grids. For example, referring to Figure 5 or Figure 6 , along the first direction X, for the edge connection line 104 on the left, the same-sex grid lines are the first thin grids 101 and the opposite-sex grid lines are the second thin grids 102; for the edge connection line 104 on the right, the same-sex grid lines are the second thin grids 102 and the opposite-sex grid lines are the first thin grids 101.

[0039] Thirdly, Figures 1 to 4 In all of them, the outlines of the local areas of the back-contact battery are schematically shown by relatively dense dashed lines. Figure 5 and Figure 6 In, the two sides of the back-contact battery along the first direction X are schematically shown by truncated wavy lines, and the truncated wavy lines are drawn with dashed lines. Figure 5 and Figure 6 The difference between and is that: Figure 5 The back-contact battery shown in is a whole-piece battery. Figure 6 The back-contact battery shown in is a half-piece battery.

[0040] It should be noted that at least one edge connection line 104 is correspondingly arranged on at least one edge area 110. For any edge connection line 104, the polarity of the grid line to which the edge connection line 104 is connected to the pad 103 closest to it is the same, that is, the edge connection line 104 and the pad 103 closest to the edge connection line 104 are both electrically connected to the same-sex grid lines. In this way, when a solder tape electrically connected to it is subsequently arranged at the pad 103, for the carriers in the part of the same-sex grid lines close to the edge area 110, not only can the carriers be transmitted to the solder tape through the area where the same-sex grid lines face the solder tape, but also the carriers can be transmitted to the edge connection line 104 by relying on the electrical connection between the same-sex grid lines and the edge connection line 104, and then be transmitted to the pad through the first connection part 105 and the pad in sequence. In other words, even if the electrical connection of the part of the same-sex grid lines facing the solder tape is poor, the carriers in the part of the same-sex grid lines close to the edge area 110 can still be collected by means of the edge connection line 104, the first connection part 105 and the pad, which is beneficial to improving the collection efficiency of carriers in the back-contact battery.

[0041] Moreover, by means of the design that the edge connection line 104 and the pad 103 closest to the edge connection line 104 are both electrically connected to the same-sex gate lines, the flow path of carriers in the same-sex gate lines can be increased, avoiding the problem that carriers cannot be effectively collected when the part of the same-sex gate line facing the solder strip is poorly electrically connected. Thus, it is beneficial to achieve uniform current flow in the back-contact battery, so as to improve the overall electrical performance of the back-contact battery, such as current density homogenization, thereby improving the uniformity of the overall photoelectric conversion efficiency of the back-contact battery, and avoiding local heating problems caused by excessive current differences in different regions of the back-contact battery, so as to enhance the thermal spot resistance performance of the back-contact battery.

[0042] Furthermore, the thickened part 114 of the edge connection line 104 is designed to be electrically connected not only to the same-sex gate lines located in the edge region 120, but also to the same-sex gate lines disconnected by the second connection part 106 in the central region 130. In other words, the thickened part 114 of the edge connection line 104 not only extends to the part connected to the first connection part 105, but also further extends in the direction closer to the central region 130. That is, at least part of the thickened part 114 of the edge connection line 104 faces the first connection part 105 along the first direction X. In this way, on the basis of improving the transmission efficiency of carriers in the thickened part 114 by virtue of the larger width of the thickened part 114 in the first direction X, the thickened part 114 facing at least part of the first connection part 105 along the first direction X is beneficial to improving the collection efficiency of carriers in the same-sex gate lines disconnected by the second connection part 106. For example, it reduces the transmission resistance of carriers in the same-sex gate lines disconnected by the second connection part 106 in the edge connection line 104, so as to reduce the carrier loss during the process of carriers in the same-sex gate lines disconnected by the second connection part 106 being transmitted to the solder strip through the edge connection line 104, the first connection part 105 and the pad 103. Thus, it is beneficial to reduce the difference in carrier density between the same-sex gate lines disconnected by the second connection part 106 and the same-sex gate lines in other regions, so as to further promote the uniform current flow in the back-contact battery, and thus further improve the overall electrical performance of the back-contact battery.

[0043] It should be noted that the pad 103 located in the edge region 120 can be regarded as the starting solder point when the subsequent solder strip is in electrical contact with the back-contact battery, that is, the starting point of welding; the pad 103 located in the edge region 120 can be regarded as the ending solder point when the subsequent solder strip is in electrical contact with the back-contact battery, that is, the ending point of welding.

[0044] In some cases, when the subsequent soldering strip is electrically connected to the soldering pad 103, the soldering strip exerts a greater force on the soldering pad 103 as the starting soldering point or the tail soldering point than the soldering strip exerts on other areas in the back contact battery, and the edge area 120 is also more susceptible to a greater external force than the central area 130. Based on this, the positive projection area of ​​the soldering pad 103 as the starting soldering point or the tail soldering point on the battery substrate 100 is designed to be larger, which can not only reduce the transmission resistance of the soldering pad 103 itself, thereby helping to improve the collection efficiency of the soldering pad 103 for carriers, but also improve the alignment accuracy and connection strength between the subsequent soldering strip and the soldering pad 103, avoid the problem of cold soldering or desoldering caused by excessive force exerted by the soldering strip on the soldering pad 103 as the starting soldering point or the tail soldering point, and also help to improve the collection efficiency of the soldering pad 103 for carriers, and improve the connection stability between the subsequent soldering strip and the soldering pad 103.

[0045] In addition, based on the above considerations, the positive projection area of ​​the pad 103 on the battery substrate 100 is designed to be larger. In order to ensure the arrangement density of the fine grids on the battery substrate 100, at least one heterosexual grid line located on the side of the first connecting portion 105 close to the central area 130 will be disconnected by the pad 103. Therefore, it is necessary to design the second connecting portion 106 to electrically connect the heterosexual grid line disconnected by the pad 103 to another heterosexual grid line closest to it, so as to ensure the collection of carriers in the heterosexual grid line. Furthermore, due to the design of the second connecting portion 106, at least one like grid line will be disconnected by the second connecting portion 106, so that the portion of the disconnected like grid line close to the edge area 110 needs to transfer the carriers to the welding strip with the help of the edge connecting line 104. Therefore, the edge connecting line 104 connected to the portion of the disconnected like grid line close to the edge area 110 is designed to be a thickened portion 114, which is beneficial to improving the collection efficiency of the edge connecting line 104 for the carriers in the like grid lines disconnected by the second connecting portion 106, thereby reducing the difference in carrier density between the like grid lines disconnected by the second connecting portion 106 and the like grid lines in other regions, so as to further promote the uniform flow of current in the back contact battery, thereby further improving the overall electrical performance of the back contact battery.

[0046] The back contact battery provided by one embodiment of the present disclosure will be described in more detail below with reference to the accompanying drawings.

[0047] In some embodiments, reference Figures 2 to 6, the thickened portion 114 is electrically connected to a plurality of same-sex grid lines located on the side of the pad 103 close to the central region 130. In other words, on the side of the first connection portion 105 close to the central region 130, the thickened portion 114 is electrically connected not only to the same-sex grid lines disconnected by the second connection portion 106, but also to other same-sex grid lines adjacent to the same-sex grid lines disconnected by the second connection portion 106. Thus, the thickened portion 114 can be directly opposite to the entire second connection portion 106 in the first direction X. In this way, it is beneficial to further increase the proportion of the thickened portion 114 in the edge connection line 104, that is, more parts of the edge connection line 104 are composed of the thickened portion 114, so as to reduce the overall transmission resistance of the edge connection line 104, improve the collection efficiency and transmission efficiency of the edge connection line 104 for the same-sex grid lines, and further promote the uniform flow of current in the back-contact battery, thereby further improving the overall electrical performance of the back-contact battery.

[0048] It should be noted that Figures 2 to 6 in Figure 1 , taking the thickened portion 114 connecting 3 same-sex grid lines located on the side of the pad 103 close to the central region 130 as an example, and the same-sex grid line closest to the first connection portion 105 is disconnected by the second connection portion 106;

[0049] In some cases, referring to Figure 1 , Figure 2 or Figure 3 , on the side of the first connection portion 105 close to the central region 130, it is sufficient that the pad 103 disconnects one opposite-sex grid line and the second connection portion 106 disconnects one same-sex grid line. Then, the number of same-sex grid lines connected by the thickened portion 114 and disconnected by the second connection portion 106 is at least 1; in other cases, referring to Figure 4 , on the side of the first connection portion 105 close to the central region 130, if the pad 103 disconnects 2 opposite-sex grid lines, the second connection portion 106 needs to disconnect 2 adjacent same-sex grid lines to collect the carriers in any one of the disconnected opposite-sex grid lines. Then, the number of same-sex grid lines connected by the thickened portion 114 and disconnected by the second connection portion 106 is at least 2.

[0050] It should be noted that in practical applications, due to the different sizes of the orthographic projection areas of the designed pads on the battery substrate, the number of different-sex grid lines interrupted by the pads will be different on the side of the first connection part close to the central area. To enable the second connection part to collect the carriers in any interrupted different-sex grid line, the number of same-sex grid lines that the second connection part needs to interrupt will also change, and thus the length of the thickened part extending towards the central area will also change to ensure that the thickened part can connect to any same-sex grid line interrupted by the second connection part.

[0051] In some cases, continuing to refer to Figures 1 to 6 , the thickened part 114 is not only located on the edge area 120, but can also be located on a part of the central area 130. In other words, the thickened part 114 can further extend onto the central area 130.

[0052] In some embodiments, referring to Figure 3 , the back-contact battery may further include: a first auxiliary line 117 that is electrically connected not only to the pad 103 but also to at least one same-sex grid line on the side of the pad 103 away from the central area 130; a second auxiliary line 127 that is electrically connected not only to the pad 103 but also to at least one same-sex grid line on the side of the pad 103 close to the central area 130. In this way, the carriers in the same-sex grid lines connected to the first auxiliary line 117 can be transmitted to the pad 103 through the first auxiliary line 117, and the carriers in the same-sex grid lines connected to the second auxiliary line 127 can be transmitted to the pad 103 through the second auxiliary line 127. In other words, along the second direction Y, at least one pair of same-sex grid lines located on both sides of the pad 103 can be electrically connected to the pad 103 through the first auxiliary line 117 or the second auxiliary line 127. Even if the electrical connection of the part of the same-sex grid lines facing the solder strip is poor, the carriers in this part of the same-sex grid lines can be collected by the pad 103 through the first auxiliary line 117 or the second auxiliary line 127, and then further collected by the solder strip subsequently to improve the collection efficiency of the carriers in the back-contact battery.

[0053] It should be noted that, generally speaking, the subsequent solder tape is electrically connected to the pad 103 serving as the starting solder joint or the ending solder joint. For example, if there is a large amount of solder paste required during soldering, the area of the solder tape opposite to the pad 103 will be raised due to the stacking of the solder paste. The same-sex grid lines that are close to the pad 103 and do not directly contact and connect with the pad 103 are greatly affected by the solder paste in the subsequent solder tape. It is not easy for the solder tape to be bent within a short distance to contact and connect with the same-sex grid lines close to the pad 103, so it is easy to have problems of poor soldering or missed soldering between the solder tape and the same-sex grid lines close to the pad 103. Moreover, due to the large height drop of the solder tape within a short distance, it is easy to have problems of desoldering between the solder tape and the same-sex grid lines close to the pad 103 in the future. Based on this, the first auxiliary line 117 and the second auxiliary line 127 are designed to directly electrically connect the same-sex grid lines that are prone to poor soldering, missed soldering or desoldering problems with the subsequent solder tape to the pad 103. Even if the same-sex grid lines close to the pad 103 have poor contact with the solder tape and cannot transmit current to the solder tape, the same-sex grid lines can transmit carriers to the pad 103 through the first auxiliary line 117 or the second auxiliary line 127, and then transmit them to the solder tape. In other words, the design of the first auxiliary line 117 and the second auxiliary line 127 is beneficial to further ensure that the subsequent solder tape can collect the current in all the first fine grids 101 or all the second fine grids 102, so as to further improve the photoelectric conversion efficiency of the back contact battery.

[0054] In some cases, with reference to Figure 3 and Figure 5 、or with reference to Figure 3 and Figure 6 , the battery substrate 100 has a first welding area 140 and a second welding area 150 that are located between two edge areas 110 and are arranged alternately along the first direction X; the back contact battery may further include: a plurality of solder joints 108 that are arranged at intervals between adjacent pads 103 along the second direction Y, a first fine grid 101 located in the area where the first welding area 140 coincides with the central area 130 is electrically connected to a solder joint 108, and a second fine grid 102 located in the area where the second welding area 150 coincides with the central area 130 is electrically connected to a solder joint 108.

[0055] It should be noted that the back contact battery can be a main-gridless back contact battery, and solder tapes will be provided on the subsequent first welding area 140 and second welding area 150. On the one hand, the solder tape is electrically connected to the pad 103. Not only can the carriers in the same-sex grid lines in contact connection with the pad 103 be collected by the solder tape via the pad 103, but also the thickened portion 114 of the designed edge connection line 104 not only contacts and connects the same-sex grid lines in the edge area 120, but also contacts and connects the same-sex grid lines disconnected by the second connection portion 106 in the central area 130, so that the same-sex grid lines in the edge area 120 and some of the same-sex grid lines in the central area 130 can be collected by the solder tape via the edge connection line 104 and the pad 103 in sequence, so as to ultimately improve the collection efficiency of the solder tape for the carriers in the back contact battery; on the other hand, the solder tape will also be electrically connected to the solder joint 108 in the central area 130, so that the same-sex grid lines in the central area 130 can be directly collected by the solder joint via the solder joint 108, or can be collected by the solder tape after passing through the edge connection line 104, the first connection portion 105 and the pad 103 in sequence, which is beneficial to increasing the circulation path of the carriers in the same-sex grid lines and avoiding the problem that the carriers cannot be effectively collected when the electrical connection between the solder joint 108 and the solder tape is poor, thereby facilitating the uniform circulation of the current in the back contact battery and improving the overall electrical performance of the back contact battery, such as current density homogenization.

[0056] It should be noted that generally, the subsequent solder tape is electrically connected to the pad 103 serving as the starting solder joint or the ending solder joint. For example, if more solder paste is required during welding, the area of the solder tape opposite to the pad 103 will be raised due to the stacking of the solder paste. The solder joint 108 closer to the pad 103 is most affected by the solder paste in the subsequent solder tape, and it is not easy for the solder tape to bend within a short distance to contact and connect with the solder joint 108 close to the pad 103, so it is easy to have problems of virtual soldering or missed soldering between the solder tape and the solder joint 108 close to the pad 103. Moreover, due to the large height drop of the solder tape within a short distance, problems of de-soldering between the solder tape and the solder joint 108 close to the pad 103 are likely to occur subsequently. Based on this, the first auxiliary line 117 and the second auxiliary line 127 are designed to directly electrically connect the same-sex grid lines corresponding to the solder joint 108 that is prone to virtual soldering, missed soldering or de-soldering problems with the subsequent solder tape to the pad 103. Even if the solder joint 108 close to the pad 103 is in poor contact with the solder tape and cannot transmit the current in the same-sex grid lines corresponding to this solder joint 108 to the solder tape, the same-sex grid lines corresponding to this solder joint 108 can also directly transmit the current to the pad 103 with the help of the first auxiliary line 117 or the second auxiliary line 127, and then transmit it to the solder tape.

[0057] In addition, the first auxiliary line 117 and the second auxiliary line 127 have a limited extension length along the second direction Y and do not lie on the entire length of the central region 130 along the second direction Y. The solder joints 108 that are not in contact or connection with the first auxiliary line 117 or the second auxiliary line 127 are relatively far from the pad 103 along the first direction X. Even if the area of the solder tape opposite to the pad 103 is raised due to solder paste stacking, the solder tape can be easily bent over a long distance to come into contact and connection with the solder joints 108 that are far from the pad 103, and will not cause excessive soldering force on the solder joints 108 that are far from the pad 103. Thus, it can effectively avoid the problem of poor soldering / desoldering between the solder joints 108 that are far from the pad 103 and the solder tape, so as to ensure the connection stability between the solder joints 108 that are far from the pad 103 and the solder tape. Moreover, after the area of the solder tape opposite to the pad 103 is raised due to solder paste stacking, over a relatively long extension length, the solder tape will also bend downward due to its own gravity factor to come into contact with the solder joints 108 that are far from the pad 103.

[0058] In some examples, referring to Figure 3 , the number of the first auxiliary lines 117 in contact and connection with the same pad 103 can be only 1, which is beneficial to reducing the amount of raw materials required for preparing the first auxiliary lines 117, thereby reducing the manufacturing cost of the back-contact battery. In some other examples, the number of the first auxiliary lines in contact and connection with the same pad 103 can be multiple, and multiple first auxiliary lines are all in contact and connection with at least one solder joint close to the pad.

[0059] In some examples, continuing to refer to Figure 3 , the number of the second auxiliary lines 127 in contact and connection with the same pad 103 can be only 1, which is beneficial to reducing the amount of raw materials required for preparing the second auxiliary lines 127, thereby reducing the manufacturing cost of the back-contact battery. In some other examples, the number of the second auxiliary lines in contact and connection with the same pad 103 can be multiple, and multiple second auxiliary lines are all in contact and connection with at least one solder joint close to the pad.

[0060] In some examples, referring to Figure 5 or Figure 6 , along the second direction Y, there is a second fine grid 102 between two adjacent solder joints 108 located in the same first welding region 140; along the second direction Y, there is a first fine grid 101 between two adjacent solder joints 108 located in the same second welding region 150.

[0061] It should be noted that the back-contact battery is a main-gridless back-contact battery. A single solder joint 108 can be in contact connection with a single grid line, and the single grid line is the first fine grid 101 or the second fine grid 102. If a certain solder joint 108 is in contact connection with the first fine grid 101, there is a second fine grid 102 spaced between another solder joint 108 adjacent to the solder joint 108 along the second direction Y; if a certain solder joint 108 is in contact connection with the second fine grid 102, there is a first fine grid 101 spaced between another solder joint 108 adjacent to the solder joint 108 along the second direction Y. In other words, both the first fine grid 101 and the second fine grid 102 located in the central region 130 are single segments extending straight along the first direction X. When the subsequent solder tape is electrically connected to the solder joint 108, it is insulated from the opposite-sex grid lines located between adjacent solder joints 108. In this way, it is beneficial to enable more areas on the central region 130 to be used for laying out the first fine grid 101 and the second fine grid 102, so that there are more transmission paths for the carriers in the battery substrate 100. And based on the dual guarantee of the solder tape collecting the carriers on the same-sex grid lines through the solder joint 108 and the solder tape collecting the carriers on the same-sex grid lines through the edge connection line 104, the circulation paths of the carriers in the same-sex grid lines are enriched, further promoting the uniform circulation of the current in the back-contact battery, so as to improve the overall electrical performance of the back-contact battery, such as current density homogenization, and to enhance the anti-thermal spot performance of the back-contact battery.

[0062] In some examples, continue to refer to Figure 5 or Figure 6 , among the first fine grid 101 and the second fine grid 102 located on the edge region 120, the first fine grid 101 is disconnected on at least a partial number of second welding regions 150, and the second fine grid 102 is disconnected on at least a partial number of first welding regions 140; among the first fine grid 101 and the second fine grid 102 located in the central region 130, solder joints 108 are provided on the part of the first fine grid 101 located in the first welding region 140, and the first fine grid 101 is not disconnected on the second welding region 150, solder joints 108 are provided on the part of the second fine grid 102 located in the second welding region 150, and the second fine grid 102 is not disconnected on the first welding region 140.

[0063] In other words, both the first fine grid 101 and the second fine grid 102 located on the edge region 120 are multi-segments disconnected along the first direction X, and both the first fine grid 101 and the second fine grid 102 located in the central region 130 are single segments extending straight along the first direction X.

[0064] In some cases, refer to Figure 3 , along the first direction X, the width of the first auxiliary line 117 can be greater than the width of the second auxiliary line 127.

[0065] It should be noted that along the second direction Y, the external force on the region of the edge region 120 closer to the upper and lower edges of the battery substrate 100 is more likely to be greater. Thus, when the first auxiliary line 117 is located on the side of the pad 103 away from the central region 130 and the second auxiliary line 127 is located on the side of the pad 103 closer to the central region 130, along the second direction Y, the first auxiliary line 117 is closer to the upper and lower edges of the battery substrate 100 than the second auxiliary line 127, and the first auxiliary line 117 is more likely to be subjected to a greater external force. On this basis, it is designed that along the first direction X, the width of the first auxiliary line 117 is greater than the width of the second auxiliary line 127, which is conducive to increasing the connection area between the first auxiliary line 117 and the pad 103 and the connection area between the first auxiliary line 117 and the same-sex gate line or solder joint 108 by means of the wider first auxiliary line 117, so as to reduce the probability of poor contact, such as disconnection of contact, between the first auxiliary line 117 and the pad 103, the same-sex gate line or the solder joint 108 after being subjected to a greater external force, thereby ensuring the connection stability between the first auxiliary line 117 and the pad 103, the same-sex gate line or the solder joint 108.

[0066] In some embodiments, referring to Figures 1 to 6 , along the second direction Y, the width of the first connection portion 105 may be greater than the width of the same-sex gate line. In other words, along the second direction Y, the width of the first connection portion 105 may be greater than the width of the same-sex gate line in contact connection with the pad 103.

[0067] It should be noted that compared with the carriers collected on the same-sex gate line in contact connection with the pad 103, the first connection portion 105 collects the carriers on multiple same-sex gate lines connected to the edge connection line 104, so the carrier density collected on the first connection portion 105 is greater. Based on this, it is designed that the width of the first connection portion 105 is greater than the width of the same-sex gate line, so that the cross-sectional area of the first connection portion 105 itself is larger and its own transmission resistance is smaller, which better matches the carrier density collected in the edge connection line 104, is conducive to improving the current transmission efficiency of the first connection portion 105, and thus further improves the photoelectric conversion efficiency of the back contact battery.

[0068] Moreover, based on the large cross-sectional area of the first connection portion 105, it is conducive to increasing the contact area at the contact between the first connection portion 105 and the edge connection line 104 and the contact area at the contact between the first connection portion 105 and the pad 103, thereby improving the connection strength between the first connection portion 105 and the edge connection line 104 and the connection strength between the first connection portion 105 and the pad 103 to ensure the electrical connection stability between the edge connection line 104 and the pad 103.

[0069] In some embodiments, referring to Figure 3 , Figure 5 orFigure 6 At least one different-sex grid line on the side of the first connection portion 105 away from the central region 130 is disconnected by the pad 103; the back-contact battery may further include: a third connection portion 109 extending along the second direction Y, electrically connecting the different-sex grid lines that are disconnected by the pad 103 and are on the side of the first connection portion 105 away from the central region 130, and at least one same-sex grid line is disconnected by the third connection portion 109.

[0070] It should be noted that based on the difference in the size of the orthographic projection area of the pad 103 designed on the battery substrate 100, the number of different-sex grid lines disconnected by the pad 103 will be different. The pad 103 has a first side close to the central region 130 and a second side away from the central region 130. In addition to disconnecting the same-sex grid lines on the first side, the pad 103 may also disconnect the same-sex grid lines on the second side. Based on this, the third connection portion 109 is designed to collect the carriers in the different-sex grid lines that are disconnected by the pad 103 and are on the side of the first connection portion 105 away from the central region 130, and further transmit the carriers to another un-disconnected different-sex grid line through the third connection portion 109, so as to further ensure the collection of carriers in the different-sex grid lines.

[0071] In some embodiments, referring to Figure 5 or Figure 6 the battery substrate 100 has a plurality of welding regions 45 located between the two edge regions 110 and arranged at intervals along the first direction X; the back-contact battery may further include: a busbar portion 119, located in the region where a part of the number of welding regions 45 coincides with the edge region 120, the busbar portion 119 electrically connects a plurality of same-sex grid lines on the side of the pad 103 away from the central region 130, and there is at least one welding region 45 between the welding region 45 having the busbar portion 119 and the edge region 110.

[0072] In other words, along the first direction X, there is no busbar portion 119 on the welding region 45 closest to the edge region 110. The first fine grid 101 and the second fine grid 102 will not be disconnected on the welding region 45 closest to the edge region 110. The carriers of one of the first fine grid 101 and the second fine grid 102 are collected by the edge connection line 104, and the carriers of the other are collected by the busbar portion 119 on the welding region 45 that is the second closest to the edge region 110.

[0073] In this way, a plurality of same-sex grid lines located on the edge region 120 and not in contact connection with the pad 103 can all be in contact connection with the busbar portion 119, so that the busbar portion 119 can collect the current in a plurality of same-sex grid lines located on the edge region 120 and not in contact connection with the pad 103, and finally transmit it to the pad 103.

[0074] In some cases, with reference to Figures 5 to 7 Figure 7 ​A top-down schematic view of a combination of a pad and a busbar in a back-contact battery provided by an embodiment of the present disclosure. At least one busbar 119 may include a first end close to the pad 103 and a second end far from the pad 103. Along the first direction X, the width of the first end is greater than that of the second end.

[0075] On the one hand, the subsequent solder tape is electrically connected to the pad 103 serving as the starting solder joint or the ending solder joint. For example, if more solder paste is required during soldering, the vicinity of the pad 103 is more likely to come into contact with the molten solder paste. Therefore, in the busbar 119, compared with the second end far from the pad 103, the first end close to the pad 103 is more likely to come into contact with the molten solder paste and have a fracture problem. Based on this, it is designed that along the first direction X, the width of the first end is greater than that of the second end, which helps to reduce the risk of fracture of the first end affected by the molten solder paste based on the wider first end, so as to improve the structural stability of the busbar 119 itself.

[0076] On the other hand, along the second direction Y, the external force received by the area of the edge region 120 closer to the upper and lower edges of the battery substrate 100 is more likely to be greater. Based on this, it is designed that along the first direction X, the width of the first end is greater than that of the second end, which is beneficial to increasing the contact area between the first end and the pad 103 to improve the connection strength between the first end and the pad 103, so as to reduce the risk of the first end disconnecting from the pad 103 due to a large external force.

[0077] On yet another hand, the busbar 119 can collect carriers in multiple like-polarity grid lines located on the edge region 120 and not in contact connection with the pad 103. Then, along the direction from the edge region 120 to the central region 130, the number of like-polarity grid lines electrically connected to the busbar 119 gradually increases, and the current collected in the busbar 119 gradually increases. Designing the first end to have a larger width is beneficial to reducing the transmission resistance of the first end itself and the contact area between the first end and the pad 103, thereby reducing the transmission resistance on the path of the current transmitted from the busbar 119 to the pad 103 in multiple aspects, so as to improve the current collection ability of the busbar 119 to match multiple like-polarity grid lines, and thus the risk of overheating due to excessive current aggregation at the first end of the busbar 119 can be reduced, so as to improve the electrical performance and yield of the back-contact battery.

[0078] In addition, designing that the widths of different parts of the busbar 119 in the first direction X are different along the second direction Y is beneficial to reasonably reducing the amount of raw materials required for preparing the busbar 119, thereby reducing the manufacturing cost of the back-contact battery.

[0079] In some cases, continue to refer in combination to Figures 5 to 7In the direction pointing from the edge region 120 to the central region 130, the width of at least one bus bar 119 gradually increases in the first direction X, so the transmission resistance of the bus bar 119 itself gradually decreases, facilitating the collection of carriers in more isotropic gate lines along the way, thereby enhancing the carrier collection ability of the bus bar 119.

[0080] It should be noted that multiple bus bars 119 are designed in a single back-contact battery. As for the change in the width of different parts of any bus bar 119 in the second direction Y in the first direction X, it can be adjusted according to actual needs. In the first direction X, if the width of the first end of any bus bar 119 is designed to be greater than the width of the second end, it can improve the structural stability of the bus bar 119 itself, enhance the current collection ability of the bus bar 119, and enhance the connection strength between the first end and the pad 103 to reduce the risk of disconnection between the first end and the pad 103.

[0081] In some cases, referring to Figure 5 or Figure 6 The number of isotropic gate lines in contact connection with a single bus bar 119 can be greater than the number of isotropic gate lines in contact connection with a single pad 103. Thus, in the case where the pitch between any two adjacent isotropic gate lines in the second direction Y is basically the same, it is beneficial to make the pad 103 located in the region of the edge region 120 close to the central region 130, avoiding the pad 103 being too close to the upper and lower edges of the battery substrate 100, so as to avoid damage to the upper and lower edges of the battery substrate 100 when the subsequent solder tape is in contact connection with the pad 103.

[0082] In some cases, referring to Figure 5 or Figure 6 The edge connection line 104 may further include: an edge portion 134 located in the edge region 120 and extending in the first direction X, one end of the edge portion 134 is electrically connected to one end of the thickened portion 114, and the main body portion 124 is electrically connected to the other end of the thickened portion 114; the edge portion 134 is in contact connection with the bus bar 119 that electrically connects one of the first fine gate 101 and the second fine gate 102, and is disconnected at the bus bar 119 that electrically connects the other of the first fine gate 101 and the second fine gate 102.

[0083] In some examples, in the edge connection line 104, the edge portion 134 can be prepared together with the isotropic gate lines. In other words, both the edge portion 134 and the isotropic gate lines can be embedded in the passivation layer of the battery substrate 100 to be in contact connection with the doping layer in the battery substrate 100, so as to directly collect the carriers in the battery substrate 100 and establish a denser current collection network. In addition, both the thickened portion 114 and the main body portion 124 can be located on the surface of the passivation layer of the battery substrate 100.

[0084] In some cases, referring to Figure 6, when the single back-contact battery is a half-cell, one side of the single half-cell in one edge region 120 has a chamfered end, and the other side in the other edge region 120 has a right-angled end. To cooperate with the chamfer design of the half-cell, the end of the thickened portion 114 near the chamfered end is bent in the direction approaching the center of the half-cell along the first direction X. In other words, the thickened portion 114 near the chamfered end includes a first portion extending along the second direction Y and a second portion extending obliquely with respect to the first direction X. In contrast, the thickened portion 114 near the right-angled end can be a strip-shaped structure extending along the second direction Y.

[0085] It should be noted that when the single back-contact battery is a half-cell, along the second direction, the right-angled ends of two adjacent half-cells can be arranged adjacent to each other, or the right-angled end of one of the two adjacent half-cells is adjacent to the chamfered end of the other. In summary, both the edge connection line 104 and the pad 103 closest to the edge connection line 104 are electrically connected to the same-sex grid lines. Even if the part of the same-sex grid line facing the solder strip has poor electrical connection, the carriers in the part of the same-sex grid line close to the edge region 110 can be collected by means of the edge connection line 104, the first connection portion 105, and the pad 103, which is beneficial to improving the collection efficiency of carriers in the back-contact battery. Moreover, by means of the edge connection line 104, the circulation path of carriers in the same-sex grid line can be increased, promoting the uniform circulation of current in the back-contact battery to improve the overall electrical performance of the back-contact battery, such as current density homogenization, thereby enhancing the thermal spot resistance performance of the back-contact battery.

[0086] Furthermore, it is designed that the thickened portion 114 of the edge connection line 104 is electrically connected not only to the same-sex grid line in the edge region 120 but also to the same-sex grid line disconnected by the second connection portion 106 in the central region 130. In other words, the thickened portion 114 of the edge connection line 104 not only extends to the part connected to the first connection portion 105 but also further extends in the direction approaching the central region 130. In this way, on the basis of improving the transmission efficiency of carriers in the thickened portion 114 by means of the larger width of the thickened portion 114 in the first direction X, the thickened portion 114 facing at least part of the first connection portion 105 along the first direction X is beneficial to improving the collection efficiency of carriers in the same-sex grid line disconnected by the second connection portion 106 by the edge connection line 104. For example, it reduces the carrier loss during the process of the carriers in the same-sex grid line disconnected by the second connection portion 106 being transmitted to the solder strip by means of the edge connection line 104, the first connection portion 105, and the pad 103, which is beneficial to reducing the difference in carrier density between the same-sex grid line disconnected by the second connection portion 106 and the same-sex grid line in other regions, so as to further promote the uniform circulation of current in the back-contact battery, thereby further improving the overall electrical performance of the back-contact battery.

[0087] Another embodiment of the present disclosure provides a back-contact tandem cell, which includes the back-contact cell provided in the foregoing embodiment. The following will describe in detail the back-contact tandem cell provided in another embodiment of the present disclosure. It should be noted that the same or corresponding parts as those in the foregoing embodiment will not be described again here.

[0088] Reference Figure 8 , Figure 8 is a partial cross-sectional schematic diagram of a back-contact tandem cell provided in another embodiment of the present disclosure. The tandem cell (andem solar cell) includes: a bottom cell 129, and the bottom cell 129 is the back-contact cell provided in the foregoing embodiment; a top cell 139, and the top cell 139 is located on one side of the bottom cell 129.

[0089] In some embodiments, the top cell 139 can be one of a perovskite solar cell, a donor-acceptor cell, a cadmium telluride (CdTe) solar cell, a copper indium gallium selenide (CIGS) solar cell, or a gallium arsenide (GaAs) solar cell.

[0090] In some cases, the top cell 139 can include: a stacked first transport layer, a perovskite substrate, a second transport layer, a transparent conductive layer, and an antireflection layer. Among them, the first transport layer faces the bottom cell 129.

[0091] In some examples, the first transport layer can be one of an electron transport layer or a hole transport layer, and the second transport layer can be the other of an electron transport layer or a hole transport layer.

[0092] In some embodiments, the bandgap width of the top cell 139 can be wider than that of the bottom cell 129. Therefore, stacking the top cell 139 above the bottom cell 129 can enable the back-contact tandem cell to have a wider spectral response range, thereby maximizing the utilization of solar energy and improving the efficiency of the back-contact tandem cell.

[0093] In some embodiments, the back-contact tandem cell can further include: an intermediate connection layer (not shown in the figure), and the intermediate connection layer is connected between the bottom cell 129 and the top cell 139.

[0094] In some cases, the intermediate connection layer is generally a tunnel junction or a very thin metal or transparent electrode composite layer. Optionally, the intermediate connection layer can be a transparent conductive oxide, which has good optoelectronic properties, high photon transmittance, and high conductivity, so that the top cell 139 and the bottom cell 129 can maintain good ohmic contact.

[0095] In some other cases, the grid lines in the back-contact cell serving as the bottom cell 129 can also be used as an intermediate connection layer to achieve electrical connection with the top cell 139.

[0096] In some embodiments, in the back-contact cell serving as the bottom cell 129, the cell substrate 100 has opposite front and back surfaces. The top cell 139 can be located on the side of the front surface away from the back surface, or on the side of the back surface away from the front surface.

[0097] Another embodiment of the present disclosure provides a photovoltaic module, which is formed by connecting a plurality of back-contact cells provided in the foregoing embodiments, or by connecting a plurality of back-contact stacked cells provided in the foregoing embodiments. The photovoltaic module provided in another embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that the same or corresponding parts as those in the foregoing embodiments will not be elaborated herein.

[0098] With reference to Figure 9 、 Figure 10 and Figures 1 to 8 , the photovoltaic module includes: a battery string, which is formed by connecting a plurality of back-contact cells 40 provided in the foregoing embodiments, or by connecting a plurality of back-contact stacked cells provided in the foregoing embodiments; an encapsulant film 41 for covering the surface of the battery string; and a cover plate 42 for covering the surface of the encapsulant film 41 facing away from the battery string.

[0099] Among them, Figure 9 a partial three-dimensional schematic diagram of the battery string in the photovoltaic module provided in another embodiment of the present disclosure, Figure 10 is a partial cross-sectional schematic diagram of the photovoltaic module provided in another embodiment of the present disclosure.

[0100] In some embodiments, the back-contact cell 40 is a BC cell (Back Contact), and the BC cell includes but is not limited to an IBC cell (Interdigitated Back Contact), an HBC cell (Heterojunction Back Contact), a TBC cell (TOPCon Back Contact), or an HPBC cell (Hybrid Passivated Back Contact), etc. In addition, the back-contact cells 40 are electrically connected in the form of a whole piece or multiple sub-pieces to form a plurality of battery strings, and the plurality of battery strings are electrically connected in series and / or in parallel. The back-contact cell 40 can be a whole-piece cell or a sliced cell, and the sliced cell refers to a cell formed by cutting a complete whole-piece cell through a cutting process.

[0101] In some embodiments, with reference to Figure 9 orFigure 10 Between multiple back-contact batteries 40, they can be electrically connected through conductive strips 43. Figure 9 and Figure 10 Only one positional relationship between the back-contact batteries 40 is schematically shown. In actual applications, the grid lines of adjacent multiple back-contact batteries can also be located on different sides respectively, and then the conductive strip connects different sides of two adjacent back-contact batteries.

[0102] In some embodiments, the encapsulation film 41 includes a first encapsulation layer and a second encapsulation layer. The first encapsulation layer covers one of the front or back surfaces of the back-contact battery 40, and the second encapsulation layer covers the other of the front or back surfaces of the back-contact battery 40. Specifically, at least one of the first encapsulation layer or the second encapsulation layer can be an organic encapsulation film such as a polyvinyl butyral (PVB) film, an ethylene-vinyl acetate copolymer (EVA) film, a polyethylene octene co-elastic body (POE) film, or a polyethylene terephthalate (PET) film, or at least one of the first encapsulation layer or the second encapsulation layer can also be a film such as an EP film, an EPE film, or a PVP film. Among them, the EP film refers to a co-extruded film composed of an EVA film and a POE film stacked, the EPE film refers to a co-extruded film formed by sequentially stacking an EVA film + a POE film + an EVA film, and the PVP film refers to a co-extruded film formed by stacking a POE film + an EVA film + a POE film. The preparation method of the co-extruded film can be, during the film processing, extruding one or more raw materials onto another film that has been made in sequence, or bonding different types of films that have been made together.

[0103] In some cases, there is a demarcation line between the first encapsulation layer and the second encapsulation layer before lamination. After the lamination treatment to form the photovoltaic module, there will no longer be 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.

[0104] In some embodiments, the cover plate 42 can be a cover plate with a light-transmitting function such as a glass cover plate or a plastic cover plate. Specifically, the surface of the cover plate 42 facing the encapsulation film 41 can be a concave-convex surface or a suede surface including multiple protruding structures, so as to increase the utilization rate of 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.

[0105] In some cases, the surface of the back-contact battery 40 has multiple fine grids arranged at intervals in the second direction. During the process of constructing a battery string using the back-contact battery 40, the conductive strip 43 is electrically connected to the multiple fine grids on each of the two adjacent back-contact batteries 40 respectively.

[0106] Those of ordinary skill in the art can understand that the above embodiments are specific examples for implementing the present disclosure. In actual applications, various changes can be made in form and details without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure should be subject to the scope defined by the claims.

Claims

1. A back-contact battery, characterized in that, Comprising: A battery substrate having two edge regions opposite to each other in a first direction, two edge regions opposite to each other in a second direction, and a central region located between the two edge regions; A first fine grid and a second fine grid located on the battery substrate and arranged alternately in the second direction; A pad located in the edge region, and a single pad is electrically connected to at least one same-sex grid line; An edge connection line at least located in the edge region, and both the edge connection line and the pad closest to the edge connection line are electrically connected to the same-sex grid line; A first connection portion extending in the first direction, electrically connecting the edge connection line and the pad closest to the edge connection line; At least one opposite-sex grid line located on one side of the first connection portion close to the central region is disconnected by the pad; A second connection portion extending in the second direction, electrically connecting the opposite-sex grid line disconnected by the pad, and at least one same-sex grid line is disconnected by the second connection portion; Wherein, the edge connection line includes two thickened portions opposite to each other in the second direction, and a main body portion located between the two thickened portions. The thickened portion is electrically connected to the same-sex grid line located in the edge region and is also electrically connected to the same-sex grid line disconnected by the second connection portion located in the central region; in the first direction, the width of the thickened portion is greater than the width of the main body portion; One of the first fine grid and the second fine grid is the same-sex grid line, and the other is the opposite-sex grid line.

2. The back contact battery according to claim 1, wherein, Further comprising: A first auxiliary line electrically connected not only to the pad but also to at least one same-sex grid line located on one side of the pad away from the central region; A second auxiliary line electrically connected not only to the pad but also to at least one same-sex grid line located on one side of the pad close to the central region.

3. The back-contact battery according to claim 2, wherein, In the first direction, the width of the first auxiliary line is greater than the width of the second auxiliary line.

4. The back contact battery according to claim 2 or 3, characterized in that, The battery substrate has a first welding region and a second welding region located between the two edge regions and arranged alternately in the first direction; The back-contact battery further comprises: in the second direction, a plurality of solder joints arranged at intervals between adjacent two pads. A first fine grid located in the region where the first welding region coincides with the central region is electrically connected to a solder joint, and a second fine grid located in the region where the second welding region coincides with the central region is electrically connected to a solder joint.

5. The back contact battery according to claim 4, wherein, In the second direction, there is a second fine grid between two adjacent solder joints located in the same first welding region; in the second direction, there is a first fine grid between two adjacent solder joints located in the same second welding region.

6. The back-contact battery according to claim 1, wherein, In the second direction, the width of the first connection portion is greater than the width of the same-sex grid line.

7. The back-contact battery according to claim 1, wherein, At least one opposite-sex grid line located on one side of the first connection portion away from the central region is disconnected by the pad; The back-contact battery further includes: a third connection portion extending along the second direction, electrically connecting the hetero gate lines that are disconnected by the pad and located on the side of the first connection portion away from the central region, and at least one of the homo gate lines is disconnected by the third connection portion.

8. The back-contact battery according to claim 1, characterized in that, The battery substrate has a plurality of welding regions located between the two edge regions and arranged at intervals along the first direction; The back-contact battery further includes: a busbar portion located in a region where a partial number of the welding regions coincide with the edge region, the busbar portion electrically connecting a plurality of the homo gate lines located on the side of the pad away from the central region, and there is at least one welding region between the welding region having the busbar portion and the edge region.

9. The back-contact battery according to claim 8, wherein, The edge connection line further includes: an edge portion located in the edge region and extending along the first direction, one end of the edge portion is electrically connected to one end of the thickened portion, and the main body portion is electrically connected to the other end of the thickened portion; The edge portion is in contact connection with the busbar portion electrically connecting one of the first fine gate and the second fine gate, and is disconnected at the busbar portion electrically connecting the other of the first fine gate and the second fine gate.

10. A back-contact stacked cell, characterized in that, Comprising: a bottom cell, the bottom cell being the back-contact battery according to any one of claims 1 to 9; a top cell, the top cell being located on one side of the bottom cell.

11. A photovoltaic module, characterized in that, Comprising: a battery string formed by connecting a plurality of back-contact batteries according to any one of claims 1 to 9, or formed by connecting a plurality of back-contact stacked batteries according to claim 10; a packaging adhesive film for covering the surface of the battery string; a cover plate for covering the surface of the packaging adhesive film facing away from the battery string.

Images