Gridless back contact cells and photovoltaic modules

Abstract

This disclosure relates to the photovoltaic field, providing a gridless back-contact cell and a photovoltaic module. The gridless back-contact cell includes: a cell substrate having first and second welding areas alternately arranged along a first direction, two edge areas opposite each other along a second direction, and a central area located between the two edge areas; first and second fine grids alternately arranged on the cell substrate along the second direction; pads located in the edge areas, each pad contacting at least two adjacent fine grids of the same polarity; solder joints located in the central area, each solder joint contacting a single fine grid of the same polarity, with M fine grids of the same polarity between adjacent pads and solder joints along the second direction; connecting lines contacting and connecting to the pads, and also contacting and connecting to at least one solder joint close to the pads along the second direction; the welding area is the first welding area and the fine grid of the same polarity is the first fine grid, and / or, the welding area is the second welding area and the fine grid of the same polarity is the second fine grid, which at least helps to improve the photoelectric conversion efficiency of the gridless back-contact cell.

Description

Technical Field

[0001] This disclosure relates to the photovoltaic field, and in particular to a gridless back-contact cell and photovoltaic module. Background Technology

[0002] With the gradual depletion of fossil fuels, photovoltaic (PV) cells are becoming increasingly widely used as a new energy alternative. A PV cell is a device that converts solar energy into electrical energy. PV cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using grid lines, thus facilitating the efficient use of electrical energy. The grid lines of a PV cell play a crucial role in collecting and transporting electrons. When assembling multiple PV cells into a PV module, pads and / or solder joints are often placed on the grid lines. Subsequently, solder ribbons are used to electrically connect the grid lines of adjacent PV cells to these pads and / or solder joints.

[0003] To further mitigate the shading of the front side of photovoltaic cells by the grid lines, research on IBC cells (Interdigitated Back Contact cells) has become increasingly in-depth.

[0004] However, in IBC cells, when implementing electrical contact between the solder ribbon and the pad and / or solder joint, for a single back contact cell, the solder paste in the solder ribbon and the stress applied by the solder ribbon to the back contact cell have a significant impact at the beginning and end of the soldering process. This can easily lead to unstable electrical connection between the solder ribbon and the grid line at the beginning and end of the soldering process, thereby reducing the photoelectric conversion efficiency of the back contact cell. Therefore, it is necessary to find a more suitable way to improve the photoelectric conversion efficiency of the back contact cell. Summary of the Invention

[0005] This disclosure provides a gridless back-contact solar cell and photovoltaic module, which at least helps to improve the photoelectric conversion efficiency of the gridless back-contact solar cell.

[0006] According to some embodiments of this disclosure, one aspect of this disclosure provides a gridless back contact battery, comprising: a battery substrate having a first welding area and a second welding area alternately arranged along a first direction, and two edge areas opposite each other along a second direction, and a central area located between the two edge areas; a first fine grid and a second fine grid arranged alternately on the battery substrate along the second direction, the first fine grid being disconnected at the second welding area, and the second fine grid being disconnected at the first welding area; a solder pad located in the area of ​​the edge area within the welding area, a single solder pad being in contact with at least two adjacent fine grids of the same polarity; and a solder joint located at the welding area. In the region located in the central area of ​​the bonding area, a single solder joint is contacted and connected to a single homogeneous fine gate. M homogeneous fine gates are located between adjacent pads and solder joints along the second direction, where M is an integer greater than or equal to 0. A connecting line contacting the pad also contacts and connects to at least one solder joint near the pad along the second direction. Each homogeneous fine gate located between two opposite connecting lines along the second direction has one solder joint. The bonding area is the first bonding area and the homogeneous fine gate is the first fine gate, and / or, the bonding area is the second bonding area and the homogeneous fine gate is the second fine gate.

[0007] In some embodiments, the number of connection lines that are in contact with the same pad is multiple, and each of the multiple connection lines is in contact with at least one solder joint near the pad.

[0008] In some embodiments, at least one of the connecting lines includes a first end near the pad and a second end near the solder joint, wherein the width of the first end is greater than the width of the second end along the first direction.

[0009] In some embodiments, the gridless back contact battery further includes: a busbar located on the side of the pad away from the solder joint and on the soldering area, wherein a single busbar contacts and connects to a plurality of the same type of fine grids.

[0010] In some embodiments, the number of homogeneous fine gates that are contacted and connected to a single busbar is greater than the number of homogeneous fine gates that are contacted and connected to a single pad.

[0011] In some embodiments, along the second direction, the length of the connecting line is less than the length of the busbar; and / or, along a section perpendicular to the second direction, the cross-sectional area of ​​the connecting line is less than the cross-sectional area of ​​the busbar.

[0012] In some embodiments, the cross-sectional area of ​​the connecting line along a section perpendicular to the second direction is a first area; the cross-sectional area of ​​the isotropic fine grid along a section perpendicular to the first direction is a second area; wherein the first area is greater than the second area.

[0013] In some embodiments, the orthographic projection area of ​​the pad on the battery substrate is greater than the orthographic projection area of ​​the solder joint on the battery substrate; and / or, along a third direction, the thickness of the pad is less than the thickness of the solder joint.

[0014] In some embodiments, the number of solder joints connected by the connecting lines located on different welding zones is different.

[0015] According to some embodiments of this disclosure, another aspect of this disclosure also provides a photovoltaic module, including: a battery string, which is formed by connecting a plurality of back-contact batteries as described in any one of the above claims, or formed by connecting a plurality of back-contact batteries formed by the preparation method described in any one of the above claims; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film away from the battery string.

[0016] The technical solutions provided in this disclosure have at least the following advantages:

[0017] The pads and solder joints located in the same welding area are located in the edge area and the center area, respectively. The pads can be regarded as the starting point or the end point of the subsequent solder strip when it makes electrical contact with the battery without the main grid back contact. Based on this, the design involves connecting each pad to at least two adjacent homogeneous fine gates, and each solder joint to a single homogeneous fine gate. This approach improves the current collection efficiency of the pads, allowing current from more homogeneous fine gates to be transferred to the pads more quickly, creating a denser current collection network. This reduces the transmission distance of photogenerated carriers and lowers the series resistance of the gridless back contact cell. Furthermore, the pads serving as the starting or ending points for subsequent solder ribbons can be designed to be larger, connecting more homogeneous fine gates. This not only reduces the pad's own transmission resistance to match more homogeneous fine gates but also improves the alignment accuracy and connection strength between subsequent solder ribbons and pads. This prevents excessive pressure from the solder ribbons on the starting or ending points, which could lead to poor soldering or detachment. This contributes to improved current collection efficiency and connection stability between subsequent solder ribbons and pads. These combined benefits enhance the current collection efficiency and photoelectric conversion efficiency of the gridless back contact cell.

[0018] Furthermore, the design of the connecting lines allows the pads to be electrically connected to at least one solder joint near the pad along the second direction. In other words, the connecting lines can electrically connect solder joints located near the pads that are prone to poor soldering, missing solder, or detachment from subsequent solder strips to the pads. Even if a solder joint closer to the pad has poor contact with the solder strip and cannot transmit current to the solder strip, the solder joint can still transmit current directly to the pad via the connecting lines, and then to the solder strip. This connecting line design helps to further ensure that subsequent solder strips can collect current from all the same type of fine grid, thereby further improving the photoelectric conversion efficiency of the gridless back contact cell. Attached Figure Description

[0019] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this disclosure or the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a first partial top view of a gridless back contact battery according to an embodiment of the present disclosure;

[0021] Figure 2 This is a second partial top view of a gridless back contact battery according to an embodiment of the present disclosure;

[0022] Figure 3 This is a first partially enlarged top view of a gridless back contact battery according to an embodiment of the present disclosure;

[0023] Figure 4 This is a second partially enlarged top view of a gridless back contact battery provided in an embodiment of the present disclosure;

[0024] Figure 5 This is a third partially enlarged top view of a gridless back contact battery provided in an embodiment of the present disclosure;

[0025] Figure 6 This is a fourth partially enlarged top view of a gridless back contact battery provided in an embodiment of the present disclosure;

[0026] Figure 7 for Figure 6 The diagram shows a partial cross-sectional view of a gridless back contact battery along the first cross-sectional direction AA1.

[0027] Figure 8A partial three-dimensional schematic diagram of a photovoltaic module provided in another embodiment of this disclosure;

[0028] Figure 9 for Figure 8 The diagram shows a partial cross-sectional view of the photovoltaic module along the second cross-section direction BB1.

[0029] Explanation of reference numerals in the attached figures:

[0030] 100. Battery substrate; 101. Welding area; 111. First welding area; 121. Second welding area; 102. Edge area; 103. Center area; 104. Isotropic grid; 114. First grid; 124. Second grid; 105. Pad; 106. Solder joint; 107. Connecting line; 117. First end; 127. Second end; 108. Busbar; 118. Third end; 128. Fourth end; 109. Edge area; 40. Gridless back contact battery; 41. Encapsulating film; 42. Cover plate; 43. Conductive strip. Detailed Implementation

[0031] As can be seen from the background technology, the current collection efficiency of back contact batteries needs to be improved.

[0032] This disclosure provides a gridless back contact cell and a photovoltaic module. In the gridless back contact cell, the pads and solder joints located on the same welding area are located in the edge area and the center area, respectively. The pads can be regarded as the starting point or the end point of the subsequent solder strip when it makes electrical contact with the gridless back contact cell. Based on this, the design ensures that each pad is connected to at least two adjacent homogeneous fine gates, and each solder joint is connected to a single homogeneous fine gate. On one hand, this improves the current collection effect of the pads, allowing more current from the homogeneous fine gates to be transferred to the pads more quickly, thus establishing a denser current collection network. This reduces the transmission distance of photogenerated carriers and lowers the series resistance of the gridless back contact cell. On the other hand, the pads that connect to more homogeneous fine gates, serving as the starting or ending points of subsequent solder ribbons, can be designed to be larger. This not only reduces the transmission resistance of the pads themselves to match more homogeneous fine gates but also improves the alignment accuracy and connection strength between subsequent solder ribbons and pads. This avoids excessive pressure from the solder ribbons on the pads used as starting or ending points, preventing issues like cold solder joints or detachment. This contributes to improving the current collection efficiency of the pads and the connection stability between subsequent solder ribbons and pads. In summary, this approach improves both the current collection efficiency and the photoelectric conversion efficiency of the gridless back contact cell. Furthermore, the design of the connecting lines allows the pads to be electrically connected to at least one solder joint near the pad along the second direction. In other words, the connecting lines can electrically connect solder joints located near the pads that are prone to poor soldering, missing solder, or detachment from subsequent solder strips to the pads. Even if a solder joint closer to the pad has poor contact with the solder strip and cannot transmit current to the solder strip, the solder joint can still transmit current directly to the pad via the connecting lines, and then to the solder strip. This connecting line design helps to further ensure that subsequent solder strips can collect current from all the same type of fine grid, thereby further improving the photoelectric conversion efficiency of the gridless back contact cell.

[0033] In the description of the embodiments of this disclosure, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary or secondary relationship of the indicated technical features. In the description of the embodiments of this disclosure, "a plurality of" means two or more, unless otherwise explicitly defined.

[0034] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this disclosure. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0035] In the description of the embodiments of this disclosure, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0036] In the description of embodiments of this disclosure, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0037] In the description of the embodiments of this disclosure, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this disclosure.

[0038] In the description of the embodiments of this disclosure, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0039] In the accompanying drawings corresponding to the embodiments of this disclosure, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0040] In the description of embodiments of this disclosure, when a component "includes" another component, other components are not excluded unless otherwise stated, and may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can 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 be present therein. Additionally, 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 indicates that no other components are located therein.

[0041] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "component" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0042] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this disclosure to facilitate a better understanding of the embodiments. However, the technical solutions claimed in the embodiments of this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0043] This disclosure provides an embodiment of a gridless back contact battery. The following will describe in detail the gridless back contact battery provided in this disclosure with reference to the accompanying drawings.

[0044] refer to Figure 1 or Figure 2The gridless back contact battery includes: a battery substrate 100, which has a first welding area 111 and a second welding area 121 arranged alternately along a first direction X, two edge areas 102 opposite each other along a second direction Y, and a central area 103 located between the two edge areas 102; a first fine grid 114 and a second fine grid 124 arranged alternately along the second direction Y on the battery substrate 100, wherein the first fine grid 114 is disconnected at the second welding area 121 and the second fine grid 124 is disconnected at the first welding area 111; a pad 105 located in the area of ​​the welding area 101 located in the edge area 102, and a single pad 105 is in contact with at least two adjacent identical fine grids 104; and a solder joint 106 located in the welding area 111. In region 103 of 01, a single solder joint 106 is in contact with a single isotropic fine gate 104. There are M isotropic fine gates 104 between adjacent pads 105 and solder joints 106 along the second direction Y, where M is an integer greater than or equal to 0. The connecting line 107 in contact with the pad 105 is also in contact with at least one solder joint 106 near the pad 105 along the second direction Y, and each isotropic fine gate 104 between two opposite connecting lines 107 along the second direction Y has a solder joint 106. The soldering region 101 is a first soldering region 111 and the isotropic fine gate 104 is a first fine gate 114, and / or, the soldering region 101 is a second soldering region 121 and the isotropic fine gate 104 is a second fine gate 124.

[0045] in, Figure 1 This is a first partial top view of a gridless back contact battery according to an embodiment of the present disclosure; Figure 2 This is a second partial top view schematic diagram of a gridless back contact battery according to an embodiment of this disclosure. It should be noted that... Figure 1 and Figure 2 The first fine grid 114 is indicated by a thicker solid line, and the second fine grid 124 is indicated by a thinner solid line.

[0046] It is worth noting that pad 105 is located in the edge region 102 of the welding area 101, that is, pad 105 is located in the region where welding area 101 and edge region 102 overlap; solder point 106 is located in the center region 103 of the welding area 101, that is, solder point 106 is located in the region where welding area 101 and center region 103 overlap. Thus, pad 105 and solder point 106, located in the same welding area 101, are located in the edge region 102 and center region 103, respectively. Pad 105 can be regarded as the starting point of the subsequent solder strip when it makes electrical contact with the battery without a main grid back contact, that is, the beginning of the welding, or as the end point of the subsequent solder strip when it makes electrical contact with the battery without a main grid back contact, that is, the end of the welding. In practical applications, not only when the solder ribbon contacts and connects with the pad 105 and solder joint 106, the solder ribbon exerts a greater force on the pad 105, which serves as the starting or ending point of the soldering, compared to the solder joint 106; but also, compared to the central area 103, the edge area 102 is more susceptible to greater external forces, making the pad 105 more susceptible to greater external forces than the solder joint 106.

[0047] Based on this, a single pad 105 is designed to be in contact with at least two adjacent homogeneous fine gates 104, and a single solder point 106 is in contact with a single homogeneous fine gate 104. In other words, the number of homogeneous fine gates 104 connected to a single pad 105 is greater than the number of homogeneous fine gates 104 connected to a single solder point 106. On the one hand, it improves the current collection effect of the pad 105, allowing more current from the same-type fine grid 104 to be transferred to the pad 105 more quickly, thus establishing a denser current collection network. This reduces the transmission distance of photogenerated carriers and lowers the series resistance of the gridless back contact cell. On the other hand, the pad 105, which serves as the starting or ending point of subsequent solder ribbons, can be designed to be larger if it connects more of the same-type fine grid 104. This not only reduces the transmission resistance of the pad 105 itself to match more of the same-type fine grid 104, but also improves the alignment accuracy and connection strength between the subsequent solder ribbons and the pad 105. This avoids excessive pressure from the solder ribbons on the pad 105, which could cause poor soldering or detachment, thus contributing to the improvement of the current collection efficiency of the pad 105 and the connection stability between the subsequent solder ribbons and the pad 105. In summary, these factors contribute to improving the current collection efficiency and photoelectric conversion efficiency of the gridless back contact cell.

[0048] The size of the pad 105 can be at least one of the diameter of the pad 105, the length of the pad 105, or the width of the pad 105.

[0049] In some cases, the projected area of ​​a single pad 105 on the battery substrate 100 can be larger than the projected area of ​​a single solder joint 106 on the battery substrate 100.

[0050] Furthermore, the design of the connecting line 107 allows the pad 105 to be electrically connected to at least one solder point 106 located near the pad 105 along the second direction Y. It is worth noting that, generally, subsequent solder ribbons contact the pad 105, which serves as the starting or ending point of the soldering process. For example, if a large amount of solder paste is required during soldering, the area of ​​the solder ribbon directly opposite the pad 105 will be raised due to the solder paste buildup. The solder point 106 located closer to the pad 105 is most affected by the solder paste in the subsequent solder ribbon. The solder ribbon is not easily bent to contact the solder point 106 near the pad 105 within a short distance, making it prone to cold solder joints or missing solder joints between the solder ribbon and the solder point 106 close to the pad 105. Moreover, because the solder ribbon descends a significant height within a short distance, subsequent desoldering between the solder ribbon and the solder point 106 close to the pad 105 is more likely to occur. Based on this, the connection line 107 is designed to directly connect the solder joints 106, which are prone to poor soldering, missing solder, or detachment with subsequent solder ribbons, to the pads 105. Even if the solder joints 106, which are close to the pads 105, have poor contact with the solder ribbon and cannot transmit current to the solder ribbon, the solder joints 106 can still transmit current directly to the pads 105 via the connection line 107, and then to the solder ribbon. In other words, the design of the connection line 107 helps to further ensure that the subsequent solder ribbons can collect current from all the same type of fine grids 104, such as all the first fine grids 114 or all the second fine grids 124, so as to further improve the photoelectric conversion efficiency of the gridless back contact cell.

[0051] Furthermore, each isotropic microgate 104 located between two opposing connection lines 107 along the second direction Y has a solder joint 106. It is worth noting that the connection lines 107 have a limited length along the second direction Y and do not extend along the entire length of the central region 103 along the second direction Y. The design of a solder joint 106 on each isotropic microgate 104 located between two opposing connection lines 107 along the second direction Y facilitates the collection of current in either isotropic microgate 104 between the two connection lines 107 by the corresponding solder joint 106. Furthermore, the solder joint 106, which is not in contact with the connecting line 107, is far from the pad 105 along the second direction Y. Even if the area of ​​the solder ribbon directly opposite the pad 105 is raised due to solder paste stacking, the solder ribbon can easily bend over a long distance to contact the solder joint 106, which is far from the pad 105, without causing excessive soldering pull on the solder joint 106, which is far from the pad 105. This can effectively avoid the problem of cold solder joints / detachment between the solder joint 106, which is far from the pad 105, and the solder ribbon, so as to ensure the connection stability between the solder joint 106, which is far from the pad 105, and the solder ribbon.

[0052] It is worth noting that the area of ​​the solder ribbon directly opposite the pad 105 will be raised due to the solder paste stacking. Over a longer extension, the solder ribbon will also bend downwards due to its own gravity to contact the solder joint 106, which is farther away from the pad 105.

[0053] It should be noted that the design includes M identical fine gates 104 between adjacent pads 105 and solder joints 106 along the second direction Y. For example, refer to... Figure 1 When M is 0, there are no isotropic fine gates 104 between adjacent pads 105 and solder joints 106 along the second direction Y; Reference Figure 2 When M is greater than 0, there is a thin gate 104 of the same type between adjacent pads 105 and solder joints 106 along the second direction Y. Moreover, the connecting line 107 contacts and connects at least simultaneously adjacent pads 105 and solder joints 106 along the second direction Y. Regardless of whether there is a thin gate 104 of the same type between adjacent pads 105 and solder joints 106 along the second direction Y, the current in the thin gate 104 that contacts and connects to the solder joint 106 can be collected by the connecting line 107.

[0054] Furthermore, when there are homogeneous fine gates 104 spaced between adjacent pads 105 and solder points 106 along the second direction Y, on the one hand, the connecting line 107 can also contact and connect with the homogeneous fine gates 104 located between adjacent pads 105 and solder points 106 to collect current from a larger number of homogeneous fine gates 104; on the other hand, designing that there are homogeneous fine gates 104 spaced between adjacent pads 105 and solder points 106 along the second direction Y is beneficial to increase the distance between adjacent pads 105 and solder points 106 along the second direction Y, and increase the height of the solder strip from being raised at the pad 105 to being lowered to the height of the pad 105. The height at which the adjacent solder joint 106 is located allows for bending. In other words, it reduces the bending height required per unit length of the solder strip in the second direction Y, thus reducing the degree of bending required per unit length. This helps to reduce the difficulty of bending the solder strip to the solder joint 106 adjacent to the pad 105, and further reduces the welding pull caused by the solder strip to the solder joint 106 adjacent to the pad 105. This effectively avoids the problem of cold solder joints / detachment between the solder joint 106 adjacent to the pad 105 and the solder strip, ensuring the connection stability between the solder joint 106 adjacent to the pad 105 and the solder strip.

[0055] In some cases, the solder area 101 may include two types: a first solder area 111 and a second solder area 121. The same type of fine gate 104 may include two types: a first fine gate 114 and a second fine gate 124. The pad 105 may also include two types: a first pad and a second pad. The first pad is located in the first solder area 111 and is in contact with a portion of the first fine gate 114, while the second pad is located in the second solder area 121 and is in contact with a portion of the second fine gate 124. Similarly, the solder joint 106 may include two types: a first solder joint and a second solder joint. The first solder joint is located in the first solder area 111 and is in contact with a first fine gate 114, while the second solder joint is located in the second solder area 121 and is in contact with a second fine gate 124. It should be noted that the pad 105 described below may refer to at least one of the first pad and the second pad, and the solder joint 106 may refer to at least one of the first solder joint and the second solder joint.

[0056] The following description, in conjunction with the accompanying drawings, will provide a more detailed account of an embodiment of this disclosure.

[0057] In some embodiments, reference Figure 1 or Figure 2 The number of connecting lines 107 that are in contact with the same pad 105 can be as small as one, which helps to reduce the amount of raw materials required to prepare the connecting lines 107, thereby reducing the preparation cost of gridless back contact cells.

[0058] In other embodiments, reference is made to... Figure 3 or Figure 4 The number of connecting lines 107 that are in contact with the same pad 105 can be multiple, and each of the multiple connecting lines 107 is in contact with at least one solder joint 106 near the pad 105. In other words, the multiple connecting lines 107 that are in contact with the same pad 105 can be regarded as a group of connecting lines. Even if some of the connecting lines 107 in a group of connecting lines fail, such as breaking, and thus cannot transmit current from the solder joint 106 to the pad 105, the remaining connecting lines 107 in a group of connecting lines can still transmit current from the solder joint 106 to the pad 105, thereby helping to further ensure the high current collection efficiency of the gridless back contact cell.

[0059] in, Figure 3 This is a first partially enlarged top view of a gridless back contact battery according to an embodiment of the present disclosure; Figure 4 This is a second partially enlarged top view schematic diagram of a gridless back-contact battery according to an embodiment of this disclosure. It should be noted that... Figure 3 and Figure 4 The first fine grid 114 is indicated by a thicker solid line, and the second fine grid 124 is indicated by a thinner solid line.

[0060] It should be noted that, Figure 3 and Figure 4 Taking the example of multiple connecting lines 107 that are in contact with the same pad 105 and are all in contact with the solder point 106 closest to the pad 105, in actual applications, the number of solder points that different connecting lines in the multiple connecting lines that are in contact with the same pad can be the same or different. For example, in a group of connecting lines, one connecting line is only in contact with one solder point, and another connecting line is in contact with solder points 2, 3 or 4.

[0061] In some embodiments, reference Figure 4 or Figure 5 , Figure 5 This is a third partially enlarged top view of a gridless back contact battery provided in an embodiment of the present disclosure. At least one connecting line 107 may include a first end 117 near the pad 105 and a second end 127 near the solder joint 106. Along the first direction X, the width of the first end 117 is greater than the width of the second end 127.

[0062] It is worth noting that the subsequent solder strip contacts the pad 105, which serves as the starting or ending point of the solder joint. For example, if a large amount of solder paste is required during soldering, the area near the pad 105 is more likely to come into contact with molten solder paste than the solder joint 106. Therefore, in the connecting line 107, the first end 117, which is closer to the pad 105, is more likely to come into contact with molten solder paste and breakage may occur, for example, due to the thermal expansion and contraction characteristics of molten solder paste, the first end 117 may break after cooling. Based on this, the width of the first end 117 is greater than the width of the second end 127 along the first direction X. On the one hand, this helps reduce the risk of breakage of the first end 117 due to the influence of molten solder paste, thus improving the structural stability of the connecting line 107 itself. On the other hand, when there is a homogeneous fine gate 104 between adjacent pads 105 and solder joints 106 along the second direction Y, the connecting line 107 will also collect the current in the homogeneous fine gate 104 located between adjacent pads 105 and solder joints 106. Therefore, along the central region 103 (refer to...) Figure 2 Pointing to edge area 102 (reference) Figure 2In the direction of the connection line 107, the number of homogeneous fine gates 104 electrically connected to the connection line 107 gradually increases, and the current collected in the connection line 107 gradually increases. Designing a wider first end 117 helps reduce the transmission resistance of the first end 117 itself and the contact area between the first end 117 and the pad 105. This reduces the transmission resistance along the path of current from the connection line 107 to the pad 105, improving the current collection capability of the connection line 107 to match the multiple homogeneous fine gates 104, thereby reducing the first end of the connection line 107. To mitigate the risk of overheating at point 117 due to excessive current accumulation, the electrical performance and yield of the gridless back contact battery are improved. On the other hand, when the solder ribbon contacts and connects with the pad 105 and solder joint 106, the solder ribbon generates greater welding stress on the pad 105, which serves as the starting or ending point of the soldering. The design of a wider first end 117 is beneficial to increase the contact area between the first end 117 and the pad 105, thereby improving the connection strength between the first end 117 and the pad 105 and reducing the risk of the first end 117 breaking off from the pad 105 due to greater welding stress.

[0063] In addition, the different widths of the different portions of the connecting line 107 along the second direction Y along the first direction X are designed to help to reasonably reduce the amount of raw materials required to prepare the connecting line 107, thereby reducing the preparation cost of the gridless back contact battery.

[0064] In some cases, continue to refer to Figure 4 or Figure 5 In the same soldering area 101, among the pads 105 and solder joints 106, along the direction from solder joint 106 to pad 105, that is, along the center area 103 to the edge area 102 (reference). Figure 2 In the direction of X, the width of at least one connecting line 107 gradually increases, and the transmission resistance of the connecting line 107 itself gradually decreases. This facilitates the collection of more current from the same type of fine grid 104 along the way, thereby improving the current collection capability of the connecting line 107. It also helps to reduce the risk of overheating in the area of ​​the connecting line 107 near the pad 105 due to excessive current accumulation, thereby improving the electrical performance and yield of the gridless back contact battery.

[0065] It should be noted that a single gridless back contact battery is designed with multiple connecting lines 107. The width of different portions of any connecting line 107 along the second direction Y along the first direction X can be adjusted according to actual needs. Along the first direction X, designing the width of the first end 117 of any connecting line 107 to be greater than the width of the second end 127 can improve the structural stability of the connecting line 107 itself, improve the current collection capability of the connecting line 107, and improve the connection strength between the first end 117 and the pad 105 to reduce the risk of the first end 117 and the pad 105 breaking apart.

[0066] In some embodiments, reference Figures 1 to 6 , Figure 6 This is a fourth partially enlarged top view of a gridless back contact battery provided in an embodiment of the present disclosure. The gridless back contact battery may further include: a busbar 108 located on the side of the pad 105 away from the solder joint 106 and on the soldering area 101. A single busbar 108 contacts and connects to a plurality of homogeneous fine gates 104. In this way, the plurality of homogeneous fine gates 104 located on the edge region 102 and not in contact with the pad 105 can all be in contact with the busbar 108, so that the busbar 108 can collect the current in the plurality of homogeneous fine gates 104 located on the edge region 102 and not in contact with the pad 105, and finally transmit it to the pad 105.

[0067] In some cases, refer to Figure 6 At least one busbar 108 may include a third end 118 near the pad 105 and a fourth end 128 away from the pad 105, wherein the width of the third end 118 is greater than the width of the fourth end 128 along the first direction X.

[0068] On the one hand, the subsequent solder strips contact and connect with the pads 105, which serve as the starting or ending points of the soldering process. For example, if a large amount of solder paste is required during soldering, the area near the pads 105 is more likely to come into contact with molten solder paste. Therefore, in the busbar 108, the third end 118, which is closer to the pads 105, is more likely to come into contact with molten solder paste and breakage than the fourth end 128, which is farther away from the pads 105. Based on this, the width of the third end 118 is designed to be greater than the width of the fourth end 128 along the first direction X. This helps to reduce the risk of breakage of the third end 118 due to the influence of molten solder paste, thereby improving the structural stability of the busbar 108 itself.

[0069] On the other hand, compared to the central area 103 (reference) Figure 2 ), edge area 102 (reference) Figure 2 It is more susceptible to greater external forces. Based on this, the width of the third end 118 is greater than the width of the fourth end 128 along the first direction X. This is beneficial to increase the contact area between the third end 118 and the pad 105, thereby increasing the connection strength between the third end 118 and the pad 105 and reducing the risk of the third end 118 breaking off from the pad 105 due to greater external forces.

[0070] On the other hand, the busbar 108 can collect current from multiple homogeneous fine gates 104 located on the edge region 102 and not connected to the pad 105. As the number of homogeneous fine gates 104 electrically connected to the busbar 108 gradually increases along the direction from the edge region 102 to the center region 103, the current collected in the busbar 108 gradually increases. The design of a wider third end 118 helps to reduce the transmission resistance of the third end 118 itself and the contact area between the third end 118 and the pad 105, thereby reducing the transmission resistance on the path of current from the busbar 108 to the pad 105 in multiple ways, so as to improve the current collection capability of the busbar 108 to match multiple homogeneous fine gates 104, thereby reducing the risk of overheating at the third end 118 of the busbar 108 due to excessive current accumulation, and improving the electrical performance and yield of the gridless back contact battery.

[0071] In addition, the different widths of different parts of the current collector 108 along the second direction Y along the first direction X are designed to help to reasonably reduce the amount of raw materials required to prepare the current collector 108, thereby reducing the preparation cost of the gridless back contact battery.

[0072] In some cases, continue to refer to Figure 6 102 along the border area (reference) Figure 2 ) points to the central area 103 (reference) Figure 2 In the direction of X, the width of at least one busbar 108 gradually increases, and the transmission resistance of the busbar 108 itself gradually decreases, which facilitates the collection of more current in the same type of fine grid 104 along the way, thereby improving the current collection capability of the busbar 108 and reducing the risk of overheating in the area of ​​the busbar 108 near the pad 105 due to excessive current accumulation, thereby improving the electrical performance and yield of the gridless back contact battery.

[0073] It should be noted that a single gridless back contact battery is designed with multiple busbars 108. The width of different parts of any busbar 108 along the second direction Y along the first direction X can be adjusted according to actual needs. Along the first direction X, designing the width of the third end 118 of any busbar 108 to be greater than the width of the fourth end 128 can improve the structural stability of the busbar 108 itself, improve the current collection capability of the busbar 108, and improve the connection strength between the third end 118 and the pad 105 to reduce the risk of the third end 118 and the pad 105 disconnecting.

[0074] In some cases, refer to Figures 1 to 6The number of homogeneous fine gates 104 that are in contact with a single busbar 108 can be greater than the number of homogeneous fine gates 104 that are in contact with a single pad 105. In this way, when the spacing between any two adjacent homogeneous fine gates 104 along the second direction Y is substantially the same, it is beneficial to position the pad 105 in the area of ​​the edge region 102 near the center region 103, so as to avoid the pad 105 being too close to the outer edge of the battery substrate 100, thereby avoiding damage to the outer edge of the battery substrate 100 when the subsequent solder ribbon contacts and connects with the pad 105.

[0075] In some cases, refer to Figures 1 to 6 Along the second direction Y, the length of the connecting line 107 can be less than the length of the busbar 108. It is worth noting that along the second direction Y, the length of the connecting line 107 is such that the solder strip requires a low degree of bending per unit length to ensure a stable connection between at least one solder joint 106 that contacts the connecting line 107 and the solder strip. This allows all solder joints 106 that are not in contact with the connecting line 107 to be stably connected to the solder strip. This helps to ensure that the current in each isotropic fine grid 104 located between two opposite pads 105 along the second direction Y can be collected while minimizing the length of the connecting line 107, thereby reducing the amount of raw materials required to fabricate the connecting line 107 and lowering the fabrication cost of the gridless back contact cell.

[0076] In some cases, refer to Figures 1 to 6 Along the section perpendicular to the second direction Y, the cross-sectional area of ​​the connecting line 107 is smaller than the cross-sectional area of ​​the merging section 108.

[0077] It is worth noting that the number of homogeneous fine gates 104 located between adjacent pads 105 and solder joints 106 in the second direction Y is small, for example, it can be 0. This makes the number of homogeneous fine gates 104 required to collect current in the connection line 107 less than the number of homogeneous fine gates 104 located on the edge region 102 required to collect current in the busbar 108. Therefore, the current density transmitted from the connection line 107 to the pad 105 is greater than the current density transmitted from the busbar 108 to the pad 105. Designing the cross-sectional area of ​​the connection line 107 to be smaller than the cross-sectional area of ​​the busbar 108 helps to further reduce the transmission resistance of the busbar 108 itself, so as to collect more current in the homogeneous fine gates 104 along the way, thereby improving the current collection capability of the busbar 108. It also helps to reduce the risk of overheating in the area of ​​the busbar 108 near the pad 105 due to excessive current accumulation, thereby improving the electrical performance and yield of the gridless back contact cell.

[0078] In some embodiments, reference Figures 1 to 6Along a cross-section perpendicular to the second direction Y, the cross-sectional area of ​​the connecting line 107 is the first area; along a cross-section perpendicular to the first direction X, the cross-sectional area of ​​the isotropic fine gate 104 is the second area; wherein, the first area can be larger than the second area. It is worth noting that the connecting line 107 needs to further transmit the current collected by the solder joint 106 from the isotropic fine gate 104 to the pad 105 by itself, and may further need to transmit part of the current in the isotropic fine gate 104 to the pad 105 by itself. Therefore, compared with the isotropic fine gate 104, the connecting line 107 needs to have a stronger current collection capability, and the connecting line 107 needs to maintain good electrical contact performance with both the solder joint 106 and the pad 105. Based on this, the cross-sectional area of ​​the connecting line 107 can be larger than that of the same-type fine gate 104, which helps to reduce the transmission resistance of the connecting line 107 itself, so as to improve the current collection effect, reduce the risk of overheating in the connecting line 107 due to excessive current collection, and reduce the risk of the connecting line 107 breaking off from the solder joint 106 or the pad 105.

[0079] In some embodiments, reference Figures 1 to 6 The projected area of ​​the pad 105 on the battery substrate 100 can be larger than that of the solder joint 106 on the battery substrate 100. This not only helps to reduce the transmission resistance of the pad 105 itself and improve the current collection capability of the pad 105, but also improves the alignment accuracy and connection strength between the subsequent solder ribbon and the pad 105. This avoids excessive pressure from the solder ribbon on the pad 105, which is the starting point or end point of the soldering, which may cause problems such as poor soldering or desoldering, thereby improving the connection stability between the subsequent solder ribbon and the pad 105.

[0080] In some embodiments, reference Figure 7 , Figure 7 for Figure 6 The diagram shows a partial cross-sectional view of a gridless back contact battery along the first cross-sectional direction AA1. Along the third direction Z, the thickness of the pad 105 is less than the thickness of the solder joint 106. The third direction Z is the thickness direction of the battery substrate 100.

[0081] It is worth noting that, generally speaking, the subsequent solder ribbon makes contact with the pad 105, which serves as the starting or ending point of the soldering process. For example, if a large amount of solder paste is required during soldering, the area of ​​the solder ribbon directly opposite the pad 105 will be raised due to the accumulation of solder paste. Based on this, by designing the thickness of the pad 105 to be less than the thickness of the solder joint 106, when the portion of the solder ribbon directly opposite the pad 105 and the portion of the solder ribbon directly opposite the solder joint 106 are at the same height, a certain gap can be reserved between the solder ribbon and the pad 105 to accommodate the solder paste accumulated on the pad 105. This effectively avoids the problem of poor contact between the area of ​​the solder ribbon directly opposite the pad 105 and the pad 105 due to the accumulation of solder paste. It also helps to further reduce the degree of bending of the solder ribbon, for example, so that the solder ribbon can achieve electrical connection with both the pad 105 and the solder joint 106 simultaneously without bending downwards. In addition, the thickness of the pad 105 is designed to be smaller, which can prevent the portion of the solder ribbon directly opposite the pad 105 from being raised too high by the solder paste relative to the battery substrate 100.

[0082] In some embodiments, reference Figure 1 or Figure 2 The number of solder joints 106 connected by the connecting lines 107 on different welding areas 101 can be different. It should be noted that, based on the different external pressures experienced by different welding areas 101, the number of solder joints 106 connected by the connecting lines 107 on different welding areas 101 is designed to be different. This is to effectively reduce the risk of poor contact between the solder joints 106 closer to the solder pad 105 and the solder strip, thus preventing current from being transmitted to the solder strip, while reasonably controlling the length of the connecting lines 107 in the second direction Y, so as to control the amount of raw materials required to prepare the connecting lines 107, thereby controlling the preparation cost of the gridless back contact battery.

[0083] In some cases, continue to refer to Figure 1 or Figure 2 Compared to the welding area 101 which is subject to less external pressure, designing a connecting line 107 to connect a larger number of solder joints 106 in the welding area 101 which is subject to greater external pressure helps reduce the risk of poor contact between the solder joints 106 and the solder strip caused by greater external pressure. This allows the connecting line 107 to solve the problem of more solder joints 106 that are susceptible to failure due to external pressure and cannot collect current properly.

[0084] In some examples, continue to refer to Figure 1 or Figure 2 The battery substrate 100 may also have two edge regions 109 opposite each other along the first direction X. The number of solder joints 106 connected by the connecting lines 107 on the welding area 101 closest to the edge region 109 is 3, and the number of solder joints 106 connected by the connecting lines 107 on the other welding areas 101 is 1.

[0085] In some embodiments, reference Figure 2 The battery substrate 100 may also have two edge regions 109 opposite each other along the first direction X. The solder point 106 located in the same welding area 101 and closest to the solder pad 105 is the target solder point. The number of isotropic fine grids 104 between the target solder points on the two welding areas 101 closest to the edge region 109 and the solder pad 105 is a first number, and the number of isotropic fine grids 104 between the target solder points on other welding areas 101 and the solder pad 105 is a second number. The first number is less than the second number.

[0086] It is worth noting that no solder joints 106 are provided on the isotropic fine grid 104 located between the target solder joint and the pad 105. The first number is less than the second number. Therefore, compared with the number of solder joints 106 designed on other solder areas 101, the number of solder joints 106 designed on the two solder areas 101 closest to the edge area 109 is greater. This is beneficial because, under the condition that the two solder areas 101 closest to the edge area 109 are more susceptible to external pressure, the more solder joints 106 on the two solder areas 101 closest to the edge area 109 can improve the connection stability between the solder strip and the pad 105 and solder joints 106 on the two solder areas 101 closest to the edge area 109, and reduce the number of solder joints 106 on other solder areas 101 to reduce the manufacturing cost of the gridless back contact cell.

[0087] In some examples, continue to refer to Figure 2 The number of identical fine gates 104 between the target solder joints and the pads 105 on the two soldering areas 101 closest to the edge area 109 is 0, while the number of identical fine gates 104 between the target solder joints and the pads 105 on the other soldering areas 101 is 3.

[0088] In summary, the pads 105 and solder points 106 located on the same welding area 101 are located in the edge region 102 and the center region 103, respectively. The pad 105 can be regarded as the starting point or the end point of the subsequent solder strip when it makes electrical contact with the gridless back contact cell. Based on this, it is designed that a single pad 105 is in contact with at least two adjacent homogeneous fine grids 104, and a single solder point 106 is in contact with a single homogeneous fine grid 104. On the one hand, this is beneficial to improving the current collection effect of the pad 105, so that the current in more homogeneous fine grids 104 can be transmitted to the pad 105 more quickly, in order to establish a denser current collection network, thereby reducing the transmission distance of photogenerated carriers and reducing the series resistance of the gridless back contact cell. On the other hand, as the starting point or the end point of the subsequent solder strip, the pad 105... 05. The pads 105 connecting more homogeneous fine grids 104 can be designed to be larger. This not only reduces the transmission resistance of the pads 105 themselves to match more homogeneous fine grids 104, but also improves the alignment accuracy and connection strength between subsequent solder ribbons and pads 105. This avoids excessive pressure from the solder ribbons on the pads 105, which serve as the starting or ending point of soldering, thus preventing problems such as cold solder joints or detachment. This contributes to improving the current collection efficiency of the pads 105 and enhancing the connection stability between subsequent solder ribbons and pads 105. In summary, this improves both the current collection efficiency and the photoelectric conversion efficiency of gridless back-contact solar cells.

[0089] Furthermore, the design of the connecting line 107 allows the pad 105 to be electrically connected to at least one solder point 106 located near the pad 105 along the second direction Y. In other words, the connecting line 107 can electrically connect solder points 106 located near the pad 105 that are prone to poor soldering, missing solder, or detachment from subsequent solder strips to the pad 105. Even if a solder point 106 closer to the pad 105 has poor contact with the solder strip and cannot transmit current to the solder strip, the solder point 106 can still transmit current directly to the pad 105 via the connecting line 107, and then to the solder strip. Therefore, the design of the connecting line 107 helps to further ensure that the subsequent solder strip can collect the current in all the same type of fine grid, thereby further improving the photoelectric conversion efficiency of the gridless back contact cell.

[0090] Another embodiment of this disclosure provides a photovoltaic module, which is formed by connecting multiple back-contact cells provided in the foregoing embodiments, or by connecting multiple back-contact cells formed by the preparation methods provided in the foregoing embodiments. The photovoltaic module provided in another embodiment of this disclosure will be described below with reference to the accompanying drawings. It should be noted that parts that are the same as or corresponding to those in the foregoing embodiments will not be repeated here.

[0091] Reference Figure 8 , Figure 9 as well as Figures 1 to 7The photovoltaic module includes: a battery string, which is formed by connecting multiple gridless back-contact cells 40 provided in the aforementioned embodiments; an encapsulating film 41 for covering the surface of the battery string; and a cover plate 42 for covering the surface of the encapsulating film 41 away from the battery string.

[0092] in, Figure 8 A partial three-dimensional schematic diagram of a photovoltaic module provided in another embodiment of this disclosure. Figure 9 for Figure 8 The diagram shows a partial cross-sectional view of the photovoltaic module along the second cross-section direction BB1.

[0093] In some embodiments, the gridless back contact battery 40 is a BC battery (Back Contact), which includes, but is not limited to, IBC (Interdigitated Back Contact), HBC (Heterojunction Back Contact), TBC (TOPCon Back Contact), or HPBC (Hybrid Passivated Back Contact). Furthermore, the gridless back contact battery 40 is electrically connected in a single sheet or in multiple segments to form multiple battery strings, which are electrically connected in series and / or parallel. The gridless back contact battery 40 can be a single cell or a sliced ​​cell; a sliced ​​cell refers to a cell formed by cutting a single, complete cell.

[0094] In some embodiments, reference Figure 8 or Figure 9 Multiple gridless back contact batteries 40 can be electrically connected through conductive strips 43. Figure 8 and Figure 9 The diagram only illustrates the positional relationship between one type of gridless back contact battery 40. In practical applications, the grid lines of multiple adjacent gridless back contact batteries can also be located on different sides, and the conductive strip connects the different sides of two adjacent gridless back contact batteries.

[0095] In some embodiments, the encapsulating film 41 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the front or back sides of the gridless back contact battery 40, and the second encapsulating layer covers the other of the front or back sides of the gridless back contact battery 40. Specifically, at least one of the first encapsulating layer or the second encapsulating layer can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first encapsulating layer or the second encapsulating layer can also be an EP film, EPE film, or 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 sequentially stacking EVA film, POE film, and EVA film; and PVP film refers to a co-extruded film formed by stacking POE film, EVA film, and POE film. Co-extruded films can be prepared by sequentially extruding one or more raw materials onto another pre-made film during the film processing, or by bonding different types of pre-made films together.

[0096] In some cases, the first encapsulation layer and the second encapsulation layer still have a boundary line before lamination. After lamination, the photovoltaic module will no longer have the concept of a first encapsulation layer and a second encapsulation layer. That is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0097] In some embodiments, the cover plate 42 can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate 42 facing the encapsulating film 41 can be an uneven surface or a textured surface containing multiple raised structures, thereby increasing the utilization rate of incident light. The cover plate 42 includes a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulation layer, and the second cover plate being opposite to the second encapsulation layer.

[0098] In some cases, the surface of the gridless back contact battery 40 has a plurality of fine grids spaced apart along the second direction. During the process of constructing a battery string using the gridless back contact battery 40, the conductive strip 43 is electrically connected to the plurality of fine grids on each of the two adjacent gridless back contact batteries 40.

[0099] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the embodiments of this disclosure. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the embodiments of this disclosure; therefore, the scope of protection of the embodiments of this disclosure should be determined by the scope defined in the claims.

Claims

1. A gridless back contact battery, characterized in that, include: A battery substrate having a first welding area and a second welding area arranged alternately along a first direction, and two edge areas opposite each other along a second direction, and a central area located between the two edge areas; A first fine grid and a second fine grid are located on the battery substrate and are alternately arranged along the second direction. The first fine grid is broken at the second welding area, and the second fine grid is broken at the first welding area. A pad is located in the edge region of the soldering area, and each pad is in contact with at least two adjacent isotropic fine gates. A solder joint is located in the central region of the soldering area. Each solder joint is in contact with a single isotropic fine gate. There are M isotropic fine gates between adjacent pads and solder joints along the second direction, where M is an integer greater than or equal to 0. The connecting line that is in contact with the pad is also in contact with at least one solder point close to the pad along the second direction, and each of the isotropic fine gates located between two connecting lines opposite each other along the second direction has one solder point. A busbar is located on the side of the pad away from the solder joint and on the soldering area. A single busbar contacts and connects multiple isotropic fine gates. Along a cross-section perpendicular to the second direction, the cross-sectional area of ​​the connecting line is smaller than the cross-sectional area of ​​the busbar. Wherein, the welding area is the first welding area and the isotropic fine gate is the first fine gate, and / or, the welding area is the second welding area and the isotropic fine gate is the second fine gate.

2. The gridless back contact battery according to claim 1, characterized in that, The number of connection lines that are in contact with the same pad is multiple, and each of the multiple connection lines is in contact with at least one solder joint near the pad.

3. The gridless back contact battery according to claim 1 or 2, characterized in that, At least one of the connecting lines includes a first end near the pad and a second end near the solder joint, wherein the width of the first end is greater than the width of the second end along the first direction.

4. The gridless back contact battery according to claim 1, characterized in that, The number of homogeneous fine gates that are in contact with a single busbar is greater than the number of homogeneous fine gates that are in contact with a single pad.

5. The gridless back contact battery according to claim 1, characterized in that, Along the second direction, the length of the connecting line is less than the length of the busbar.

6. The gridless back contact battery according to claim 1 or 5, characterized in that, Along a cross section perpendicular to the second direction, the cross-sectional area of ​​the connecting line is a first area; along a cross section perpendicular to the first direction, the cross-sectional area of ​​the isotropic fine grid is a second area; wherein, the first area is greater than the second area.

7. The gridless back contact battery according to claim 1, characterized in that, The positive projection area of ​​the pad on the battery substrate is greater than the positive projection area of ​​the solder joint on the battery substrate; and / or, along a third direction, the thickness of the pad is less than the thickness of the solder joint.

8. The gridless back contact battery according to claim 1, characterized in that, The number of solder joints connected by the connecting lines located in different welding zones varies.

9. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple gridless back-contact batteries as described in any one of claims 1 to 8; An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

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