Main-grid-free back contact battery and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a main-grid-free back contact battery and a photovoltaic module, and the main-grid-free back contact battery comprises a battery substrate which is provided with a first welding region and a second welding region which are alternately arranged along a first direction, two edge regions which are opposite 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 pads are located in the edge area, and each bonding pad is at least in contact connection with two adjacent homopolar fine grids; the welding spots are located in the central area, each welding spot is in contact connection with each same-polarity fine grid, and M same-polarity fine grids are arranged between the bonding pads and the welding spots which are adjacent in the second direction; the connecting line is in contact connection with the bonding pad and is also in contact connection with at least one welding spot close to the bonding pad along the second direction; the welding area is a first welding area and the same-polarity fine grid is a first fine grid, and / or the welding area is a second welding area and the same-polarity fine grid is a second fine grid, so that the photoelectric conversion efficiency of the main-grid-free back contact battery is at least improved.

Description

Technical Field

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

[0002] With the gradual depletion of fossil energy, 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 utilizes 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 assembling a plurality of photovoltaic cells to obtain a photovoltaic module, 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 solder strip to make electrical contact with the pads and / or solder joints.

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

[0004] However, in IBC cells, when implementing the electrical contact between the solder strip and the pads and / or solder joints, for a single back-contact cell, at the starting and ending welding positions of the solder strip, the influence of the solder paste in the solder strip and the stress exerted by the solder strip on the back-contact cell is relatively large, which easily causes the electrical connection between the starting and ending welding positions of the solder strip and the grid lines to be unstable, thereby reducing the photoelectric conversion efficiency of the back-contact cell. Therefore, it is necessary to seek a more suitable method to improve the photoelectric conversion efficiency of the back-contact cell. Summary of the Invention

[0005] Embodiments of the present disclosure provide a main-gridless back-contact battery and a photovoltaic module, which are at least beneficial to improving the photoelectric conversion efficiency of the main-gridless back-contact battery.

[0006] According to some embodiments of the present disclosure, on the one hand, an embodiment of the present disclosure provides a main-gridless back-contact battery, including: a battery substrate having first welding regions and second welding regions arranged alternately 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; first fine grids and second fine grids arranged alternately in the second direction on the battery substrate, the first fine grids being disconnected on the second welding regions, and the second fine grids being disconnected on the first welding regions; bonding pads located on the regions of the welding regions that are the edge regions, and each single bonding pad being in contact connection with at least 2 adjacent same-sex fine grids; welding points located on the regions of the welding regions that are the central region, each single welding point being in contact connection with a single same-sex fine grid, and there being M same-sex fine grids between the adjacent bonding pad and welding point in the second direction, where M is an integer greater than or equal to 0; connection lines in contact connection with the bonding pads and also in contact connection with at least one welding point adjacent to the bonding pad in the second direction, and there being a welding point on each same-sex fine grid located between the two connection lines opposite to each other in the second direction; wherein, the welding region is the first welding region and the same-sex fine grid is the first fine grid, and / or, the welding region is the second welding region and the same-sex fine grid is the second fine grid.

[0007] In some embodiments, the number of the connection lines in contact connection with the same bonding pad is multiple, and multiple connection lines are all in contact connection with at least one welding point adjacent to the bonding pad.

[0008] In some embodiments, at least one connection line includes a first end portion close to the bonding pad and a second end portion close to the welding point, and in the first direction, the width of the first end portion is greater than the width of the second end portion.

[0009] In some embodiments, the main-gridless back-contact battery further includes: a current collecting portion located on the side of the bonding pad away from the welding point and on the welding region, and each single current collecting portion being in contact connection with multiple same-sex fine grids.

[0010] In some embodiments, the number of the same-sex fine grids in contact connection with a single current collecting portion is greater than the number of the same-sex fine grids in contact connection with a single bonding pad.

[0011] In some embodiments, in the second direction, the length of the connection line is less than the length of the current collecting portion; and / or, in a cross-section perpendicular to the second direction, the cross-sectional area of the connection line is less than the cross-sectional area of the current collecting portion.

[0012] In some embodiments, on a cross-section perpendicular to the second direction, the cross-sectional area of the connection line is a first area; on a cross-section perpendicular to the first direction, the cross-sectional area of the same-sex fine grid 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, in the 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 in contact connection with the connection lines located on different welding areas is different.

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

[0016] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages: The pads and the solder joints located on the same welding area are respectively located in the edge area and the central area. The pad can be regarded as the starting or ending point of the subsequent solder tape in electrical contact with the main-gridless back-contact battery. On this basis, it is designed that a single pad is in contact connection with at least 2 adjacent same-sex fine grids, and a single solder joint is in contact connection with a single same-sex fine grid. On the one hand, it is beneficial to improve the current collection effect of the pad, so that the current in more same-sex fine grids can be transmitted to the pad faster to establish a denser current collection network, thereby reducing the transmission distance of photo-generated carriers and reducing the series resistance of the main-gridless back-contact battery; on the other hand, as the starting or ending point of the subsequent solder tape, the size of the pad connecting more same-sex fine grids can be designed to be larger, which can not only reduce the transmission resistance of the pad itself to match more same-sex fine grids, but also improve the alignment accuracy and connection strength between the subsequent solder tape and the pad, and avoid the problem of virtual soldering or desoldering caused by excessive pressure of the solder tape on the pad as the starting or ending point, thereby contributing to the improvement of the current collection efficiency of the pad and the connection stability between the subsequent solder tape and the pad. Considering multiple aspects comprehensively, it is beneficial to improve the current collection efficiency of the main-gridless back-contact battery and the photoelectric conversion efficiency of the main-gridless back-contact battery.

[0017] Furthermore, in combination with the design of the connection lines, the pad and at least one solder joint approaching the pad along the second direction can achieve electrical connection by means of the connection lines. In other words, the connection lines can electrically connect the solder joints near the pad that are prone to problems such as false soldering, missed soldering, or de-soldering with the subsequent solder tape. Even if the solder joints close to the pad have poor contact with the solder tape and cannot transmit current to the solder tape, the solder joints can directly transmit the current to the pad through the connection lines and then to the solder tape. Therefore, the design of the connection lines is conducive to further ensuring that the subsequent solder tape can collect the current in all the same-sex fine grids, thereby further improving the photoelectric conversion efficiency of the main-gridless back-contact battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not constitute limitations on the embodiments. Unless otherwise stated, the figures in the drawings do not constitute a scale limitation. To more clearly illustrate the technical solutions in the embodiments of the present disclosure or in the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the following-described drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 The first partial top view schematic diagram of the main-gridless back-contact battery provided by an embodiment of the present disclosure; Figure 2 The second partial top view schematic diagram of the main-gridless back-contact battery provided by an embodiment of the present disclosure; Figure 3 The first partial enlarged top view schematic diagram of the main-gridless back-contact battery provided by an embodiment of the present disclosure; Figure 4 The second partial enlarged top view schematic diagram of the main-gridless back-contact battery provided by an embodiment of the present disclosure; Figure 5 The third partial enlarged top view schematic diagram of the main-gridless back-contact battery provided by an embodiment of the present disclosure; Figure 6 The fourth partial enlarged top view schematic diagram of the main-gridless back-contact battery provided by an embodiment of the present disclosure; Figure 7 is Figure 6 A partial cross-sectional schematic diagram of the main-gridless back-contact battery shown along the first cross-section direction AA1; Figure 8 A partial three-dimensional schematic diagram of a photovoltaic module provided by another embodiment of the present disclosure; Figure 9 is Figure 8 A partial cross-sectional schematic diagram of the photovoltaic module shown along the second cross-section direction BB1.

[0020] Description of Reference Numerals: 100, battery substrate; 101, welding area; 111, first welding area; 121, second welding area; 102, edge area; 103, central area; 104, same-sex fine grid; 114, first fine grid; 124, second fine grid; 105, pad; 106, solder joint; 107, connection line; 117, first end; 127, second end; 108, bus bar portion; 118, third end; 128, fourth end; 109, edge area; 40, main-gridless back-contact battery; 41, encapsulation film; 42, cover plate; 43, conductive tape. Detailed Embodiment

[0021] As can be seen from the background art, the current collection efficiency of the back-contact battery needs to be improved.

[0022] The present disclosure provides a main-gridless back-contact battery and a photovoltaic module. In the main-gridless back-contact battery, the pads and the solder joints located on the same welding area are respectively located in the edge area and the central area. The pad can be regarded as the starting or ending point of soldering when the subsequent solder tape is in electrical contact with the main-gridless back-contact battery. On this basis, it is designed that at least two adjacent same-sex fine grids are in contact connection with a single pad, and a single solder joint is in contact connection with a single same-sex fine grid. On the one hand, it is beneficial to improve the current collection effect of the pad, so that the current in more same-sex fine grids can be transmitted to the pad faster, so as to establish a denser current collection network, thereby reducing the transmission distance of photo-generated carriers and reducing the series resistance of the main-gridless back-contact battery; on the other hand, as the starting or ending point of the subsequent solder tape, the size of the pad connecting more same-sex fine grids can be designed to be larger, which can not only reduce the transmission resistance of the pad itself to match more same-sex fine grids, but also improve the alignment accuracy and connection strength between the subsequent solder tape and the pad, avoiding the problem of virtual soldering or desoldering caused by excessive pressure of the solder tape on the pad as the starting or ending point, thereby contributing to the improvement of the current collection efficiency of the pad and the connection stability between the subsequent solder tape and the pad. Overall, it is beneficial to improve the current collection efficiency of the main-gridless back-contact battery and the photoelectric conversion efficiency of the main-gridless back-contact battery. Further, combined with the design of the connection line, the pad and at least one solder joint close to the pad along the second direction can be electrically connected by means of the connection line. In other words, the connection line can electrically connect the solder joints near the pad that are prone to virtual soldering, missed soldering or desoldering problems with the subsequent solder tape to the pad. Even if the solder joints close to the pad are in poor contact with the solder tape and cannot transmit the current to the solder tape, the solder joints can directly transmit the current to the pad through the connection line and then to the solder tape. Therefore, the design of the connection line is beneficial to further ensure that the subsequent solder tape can collect the current in all same-sex fine grids, so as to further improve the photoelectric conversion efficiency of the main-gridless back-contact battery.

[0023] 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.

[0024] Referring to "embodiments" herein means that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present disclosure. The phrase appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships can exist. 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.

[0026] In the description of the embodiments of the present disclosure, the term "a plurality" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0027] In the description of the embodiments of the present disclosure, 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. indicate the orientation or positional relationship 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 indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present disclosure.

[0028] 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 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.

[0029] In the accompanying drawings corresponding to 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, a film, a region, or a substrate) being 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. Conversely, when describing a component being on the surface of another component or when the surface of a component forms or is provided with another component, it means that there is no third component between the two components. In addition, when describing a component being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.

[0030] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise specified, other components are not excluded, and other components may further be included. In addition, when a component such as a layer, a film, a region, or a plate is referred to as being "on / located on" another component, it can be "directly on" the other component (i.e., on the surface of the other component with no other components therebetween), or there can be another component therebetween. In addition, when a component such as a layer, a film, a region, or a plate is "directly located on" another component, or when a component such as a layer, a film, a region, or a plate is located on the surface of another component, it means that no other components are located therebetween.

[0031] The terms used in the description of the various embodiments herein are only for describing specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is 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.

[0032] 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 presented for the reader to better understand the embodiments of the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the embodiments of the present disclosure can still be implemented.

[0033] An embodiment of the present disclosure provides a main-gridless back-contact battery. The main-gridless back-contact battery provided by an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0034] Reference Figure 1 or Figure 2, the main-gridless back-contact battery includes: a battery substrate 100, the battery substrate 100 having first welding regions 111 and second welding regions 121 arranged alternately along a first direction X, further having two edge regions 102 opposite to each other along a second direction Y, and a central region 103 located between the two edge regions 102; first fine grids 114 and second fine grids 124 arranged alternately along the second direction Y on the battery substrate 100, the first fine grids 114 being disconnected on the second welding regions 121, and the second fine grids 124 being disconnected on the first welding regions 111; bonding pads 105 located on the regions of the welding regions 101 that are in the edge regions 102, each single bonding pad 105 being in contact connection with at least 2 adjacent same-sex fine grids 104; solder joints 106 located on the regions of the welding regions 101 that are in the central region 103, each single solder joint 106 being in contact connection with a single same-sex fine grid 104, and there being M same-sex fine grids 104 between adjacent bonding pads 105 and solder joints 106 along the second direction Y, M being an integer greater than or equal to 0; connection lines 107 in contact connection with the bonding pads 105, further in contact connection with at least one solder joint 106 adjacent to the bonding pads 105 along the second direction Y, and there being a solder joint 106 on each same-sex fine grid 104 located between the two connection lines 107 opposite to each other along the second direction Y; wherein, the welding region 101 is the first welding region 111 and the same-sex fine grid 104 is the first fine grid 114, and / or, the welding region 101 is the second welding region 121 and the same-sex fine grid 104 is the second fine grid 124.

[0035] Wherein, Figure 1 is the first partial top view schematic diagram of the main-gridless back-contact battery provided by an embodiment of the present disclosure; Figure 2 is the second partial top view schematic diagram of the main-gridless back-contact battery provided by an embodiment of the present disclosure. It should be noted that, Figure 1 and Figure 2 both schematically show the first fine grids 114 with thick solid lines and the second fine grids 124 with thin solid lines.

[0036] It should be noted that the pad 105 is located on the area of the welding zone 101 that coincides with the edge zone 102, that is, the pad 105 is located on the area where the welding zone 101 and the edge zone 102 overlap; the solder joint 106 is located on the area of the welding zone 101 that coincides with the central zone 103, that is, the solder joint 106 is located on the area where the welding zone 101 and the central zone 103 overlap. Thus, the pad 105 and the solder joint 106 located on the same welding zone 101 are respectively located in the edge zone 102 and the central zone 103. The pad 105 can be regarded as the starting point of soldering when the subsequent solder ribbon is in electrical contact with the main-gridless back-contact cell, that is, the starting point of welding, or can be regarded as the end point of soldering when the subsequent solder ribbon is in electrical contact with the main-gridless back-contact cell, that is, the end point of welding. In practical applications, not only when the subsequent solder ribbon is in contact and connected with the pad 105 and the solder joint 106, the force of the solder ribbon on the pad 105 as the starting or ending point of soldering is greater than that on the solder joint 106; moreover, compared with the central zone 103, the edge zone 102 is more likely to be affected by greater external forces, making the pad 105 more likely to be affected by greater external forces than the solder joint 106.

[0037] On this basis, it is designed that a single pad 105 is in contact and connected with at least 2 adjacent same-sex fine grids 104, and a single solder joint 106 is in contact and connected with a single same-sex fine grid 104. In other words, it is designed that the number of same-sex fine grids 104 connected to a single pad 105 is more than the number of same-sex fine grids 104 connected to a single solder joint 106. On the one hand, it is beneficial to improve the current collection effect of the pad 105, so that the current in more same-sex fine grids 104 can be transmitted to the pad 105 faster to establish a denser current collection network, thereby reducing the transmission distance of photo-generated carriers and reducing the series resistance of the main-gridless back-contact cell; on the other hand, as the starting or ending point of the subsequent solder ribbon, the size of the pad 105 connected to more same-sex fine grids 104 can be designed to be larger. This can not only reduce the transmission resistance of the pad 105 itself to match more same-sex fine grids 104, but also improve the alignment accuracy and connection strength between the subsequent solder ribbon and the pad 105, avoiding the problem of virtual soldering or desoldering caused by excessive pressure of the solder ribbon on the pad 105 as the starting or ending point of soldering, thereby contributing to the improvement of the current collection efficiency of the pad 105 and the improvement of the connection stability between the subsequent solder ribbon and the pad 105. Considering multiple aspects comprehensively, it is beneficial to improve the current collection efficiency of the main-gridless back-contact cell and the photoelectric conversion efficiency of the main-gridless back-contact cell.

[0038] Among them, 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.

[0039] In some cases, the orthographic projection area of a single pad 105 on the battery substrate 100 can be larger than the orthographic projection area of a single solder joint 106 on the battery substrate 100.

[0040] Furthermore, in combination with the design of the connection line 107, the pad 105 and at least one solder joint 106 adjacent to the pad 105 along the second direction Y can achieve electrical connection by means of the connection line 107. It should be noted that generally, the subsequent solder strip is in contact connection with the pad 105 serving as the starting solder joint or the ending solder joint. For example, if more solder paste is required during soldering, the area of the solder strip opposite to the pad 105 will be raised due to the stacking of the solder paste. The solder joints 106 closer to the pad 105 are most affected by the solder paste in the subsequent solder strip, and it is difficult for the solder strip to bend within a short distance to make contact connection with the solder joints 106 close to the pad 105, thus prone to problems such as poor soldering or missed soldering between the solder strip and the solder joints 106 close to the pad 105. Moreover, due to the large height drop of the solder strip within a short distance, subsequent problems such as de-soldering between the solder strip and the solder joints 106 close to the pad 105 are likely to occur. Based on this, the connection line 107 is designed to directly electrically connect the solder joints 106 prone to poor soldering, missed soldering or de-soldering with the subsequent solder strip to the pad 105. Even if the solder joints 106 close to the pad 105 are in poor contact with the solder strip and cannot transmit current to the solder strip, the solder joints 106 can directly transmit the current to the pad 105 through the connection line 107 and then to the solder strip. In other words, the design of the connection line 107 is beneficial to further ensure that the subsequent solder strip can collect the current of all the same-sex 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 main-gridless back-contact battery.

[0041] In addition, it is designed that each same-sex fine grid 104 located between two connection lines 107 opposite to each other along the second direction Y has a solder joint 106. It should be noted that the extension length of the connection line 107 along the second direction Y is limited and does not cover the entire length of the central area 103 along the second direction Y. Designing a solder joint 106 on each same-sex fine grid 104 located between two connection lines 107 opposite to each other along the second direction Y is beneficial to ensure that the current in any same-sex fine grid 104 located between the two connection lines 107 can be collected by the corresponding solder joint 106. Furthermore, the solder joints 106 not in contact connection with the connection line 107 are farther away from the pad 105 along the second direction Y. Even if the area of the solder strip opposite to the pad 105 is raised due to the stacking of the solder paste, the solder strip is easy to bend within a long distance to make contact connection with the solder joints 106 farther away from the pad 105, and will not cause excessive soldering tension on the solder joints 106 farther away from the pad 105, thereby effectively avoiding problems such as poor soldering / de-soldering between the solder joints 106 farther away from the pad 105 and the solder strip, and ensuring the connection stability between the solder joints 106 farther away from the pad 105 and the solder strip.

[0042] It should be noted that after the area of the solder strip facing the pad 105 is raised due to solder paste stacking, on a relatively long extension length, the solder strip will also bend downward due to its own gravity to contact the solder joint 106 that is farther away from the pad 105.

[0043] It should be noted that there are M same-sex fine grids 104 between the pad 105 and the solder joint 106 adjacent along the second direction Y. For example, referring to Figure 1 , when M is 0, there is no same-sex fine grid 104 between the pad 105 and the solder joint 106 adjacent along the second direction Y; referring to Figure 2 , when M is greater than 0, the same-sex fine grids 104 are spaced between the pad 105 and the solder joint 106 adjacent along the second direction Y. Moreover, the connecting line 107 contacts and connects at least the pad 105 and the solder joint 106 adjacent along the second direction Y at the same time. Whether there are same-sex fine grids 104 between the pad 105 and the solder joint 106 adjacent along the second direction Y or not, the current in the same-sex fine grid 104 in contact with the solder joint 106 can be collected by the connecting line 107.

[0044] In addition, when there are same-sex fine grids 104 between the pad 105 and the solder joint 106 adjacent along the second direction Y, on the one hand, the connecting line 107 can also contact and connect with the same-sex fine grids 104 located between the adjacent pad 105 and the solder joint 106 to collect the current in a larger number of same-sex fine grids 104; on the other hand, designing that there are same-sex fine grids 104 between the pad 105 and the solder joint 106 adjacent along the second direction Y is beneficial to increasing the distance between the pad 105 and the solder joint 106 adjacent along the second direction Y, increasing the length that the solder strip can be bent when the height of the solder strip raised at the pad 105 is reduced to the height of the solder joint 106 adjacent to the pad 105. In other words, it can reduce the height required for the solder strip to bend per unit length in the second direction Y, that is, reduce the bending degree required for the solder strip per unit length, which is beneficial to reducing the difficulty of the solder strip bending to the solder joint 106 adjacent to the pad 105, and further beneficial to reducing the soldering tension caused by the solder strip to the solder joint 106 adjacent to the pad 105, so as to effectively avoid the problem of virtual soldering / de-soldering between the solder joint 106 adjacent to the pad 105 and the solder strip, and ensure the connection stability between the solder joint 106 adjacent to the pad 105 and the solder strip.

[0045] In some cases, based on the fact that the welding area 101 includes two types, namely the first welding area 111 and the second welding area 121, the same-sex fine grid 104 includes two types, namely the first fine grid 114 and the second fine grid 124, and the pad 105 can also include two types, namely the first pad and the second pad. Among them, the first pad is located in the first welding area 111 and is in contact connection with some of the first fine grids 114, and the second pad is located in the second welding area 121 and is in contact connection with some of the second fine grids 124. In addition, the solder joint 106 can also include two types, namely the first solder joint and the second solder joint. Among them, the first solder joint is located in the first welding area 111 and is in contact connection with a first fine grid 114, and the second solder joint is located in the second welding area 121 and is in contact connection with a second fine grid 124. It should be noted that the pad 105 described later can refer to at least one of the first pad and the second pad, and the solder joint 106 can refer to at least one of the first solder joint and the second solder joint.

[0046] A more detailed description of an embodiment of the present disclosure will be given below with reference to the accompanying drawings.

[0047] In some embodiments, referring to Figure 1 or Figure 2 , the number of connection lines 107 in contact connection with the same pad 105 can be only 1, which is beneficial to reducing the amount of raw materials required for preparing the connection lines 107, thereby reducing the preparation cost of the main-gridless back-contact battery.

[0048] In some other embodiments, referring to Figure 3 or Figure 4 , the number of connection lines 107 in contact connection with the same pad 105 can be multiple, and multiple connection lines 107 are all in contact connection with at least one solder joint 106 close to the pad 105. In other words, the multiple connection lines 107 in contact connection with the same pad 105 can be regarded as a group of connection line groups. Even if some of the connection lines 107 in a group of connection line groups fail, such as breakage, resulting in the inability to transmit current from the solder joint 106 to the pad 105, the remaining connection lines 107 in a group of connection line groups can still transmit current from the solder joint 106 to the pad 105, which is beneficial to further ensuring a high current collection efficiency of the main-gridless back-contact battery.

[0049] Among them, Figure 3 is the first partial enlarged top view schematic diagram of the main-gridless back-contact battery provided by an embodiment of the present disclosure; Figure 4 is the second partial enlarged top view schematic diagram of the main-gridless back-contact battery provided by an embodiment of the present disclosure. It should be noted that Figure 3 and Figure 4 both show the first fine grid 114 with a thick solid line and the second fine grid 124 with a thin solid line.

[0050] It should be noted thatFigure 3 and Figure 4 Taking as an example that multiple connection lines 107 in Figure 4 which are in contact connection with the same pad 105 are all in contact connection with one solder joint 106 closest to the pad 105, in practical applications, the number of solder joints that different connection lines among multiple connection lines in contact connection with the same pad are in contact connection with can be the same or different. For example, in a group of connection line groups, one connection line is only in contact connection with 1 solder joint, and another connection line is in contact connection with 2, 3 or 4 solder joints.

[0051] In some embodiments, referring to Figure 4 or Figure 5 , Figure 5 is the third partial enlarged top view schematic diagram of the back contact battery without main grid provided by an embodiment of the present disclosure. At least one connection line 107 may include a first end 117 close to the pad 105 and a second end 127 close to 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.

[0052] It should be noted that the subsequent solder tape is in contact connection with the pad 105 serving as the starting or ending soldering point. For example, if more solder paste is required during soldering, it is easier to contact the molten solder paste near the pad 105 than at the solder joint 106. Therefore, among the connection lines 107, the first end 117 close to the pad 105 is more likely to contact the molten solder paste and have a breakage problem. For example, affected by the thermal expansion and contraction characteristics of the molten solder paste, the first end 117 breaks after cooling. Based on this, it is designed that along the first direction X, the width of the first end 117 is greater than the width of the second end 127. On the one hand, it helps to reduce the risk of breakage of the first end 117 affected by the molten solder paste based on the wider first end 117 to improve the structural stability of the connection line 107 itself; on the other hand, when a same-sex fine grid 104 is spaced between the adjacent pad 105 and solder joint 106 along the second direction Y, the connection line 107 will also collect the current in the same-sex fine grid 104 located between the adjacent pad 105 and solder joint 106. Then along the central region 103 (referring to Figure 2 ), Figure 2In the direction of (), the number of the same-sex fine grids 104 electrically connected to the connection line 107 gradually increases, and the current converged in the connection line 107 gradually increases. Designing the width of the first end portion 117 to be larger is beneficial to reducing the transmission resistance of the first end portion 117 itself and the contact area between the first end portion 117 and the pad 105, thereby reducing the transmission resistance on the path of the current transmitted from the connection line 107 to the pad 105 in multiple aspects, so as to improve the current collection ability of the connection line 107 to match multiple same-sex fine grids 104, thereby reducing the risk of overheating due to excessive current aggregation at the first end portion 117 of the connection line 107, and improving the electrical performance and yield of the main-gridless back-contact battery; on the other hand, when the subsequent solder strip is in contact connection with the pad 105 and the solder joint 106, the welding stress generated by the solder strip on the pad 105 serving as the starting welding point or the ending welding point is greater. Designing the width of the first end portion 117 to be larger is beneficial to increasing the contact area between the first end portion 117 and the pad 105 to improve the connection strength between the first end portion 117 and the pad 105, so as to reduce the risk of the first end portion 117 being disconnected from the pad 105 due to the large welding stress.

[0053] In addition, designing that the widths of different parts of the connection line 107 in the second direction Y in the first direction X are different is beneficial to reasonably reducing the amount of raw materials required for preparing the connection line 107, thereby reducing the manufacturing cost of the main-gridless back-contact battery.

[0054] In some cases, continue to refer to Figure 4 or Figure 5 , among the pad 105 and the solder joint 106 in the same welding area 101, in the direction from the solder joint 106 to the pad 105, that is, in the direction from the central area 103 to the edge area 102 (refer to Figure 2 ), in the direction of (), the width of at least one connection line 107 in the first direction X gradually increases, then the transmission resistance of the connection line 107 itself gradually decreases, which is convenient for collecting more current in the same-sex fine grids 104 along the way, so as to improve the current collection ability of the connection line 107, and is beneficial to reducing the risk of overheating due to excessive current aggregation in the area where the connection line 107 is close to the pad 105, and improving the electrical performance and yield of the main-gridless back-contact battery.

[0055] It should be noted that multiple connection lines 107 are designed in a single main-gridless back-contact battery. As for the change in the width of different parts of any connection line 107 in the first direction X in the second direction Y, it can be adjusted according to actual needs. In the first direction X, designing the width of the first end portion 117 of any connection line 107 to be larger than the width of the second end portion 127 can improve the structural stability of the connection line 107 itself, improve the current collection ability of the connection line 107, and improve the connection strength between the first end portion 117 and the pad 105 to reduce the risk of the first end portion 117 being disconnected from the pad 105.

[0056] In some embodiments, referring to Figures 1 to 6 , Figure 6 FIG. 4 is a fourth partially enlarged top view schematic diagram of a main-gridless back-contact battery provided by an embodiment of the present disclosure. The main-gridless back-contact battery may further include: a busbar portion 108, located on a side of the pad 105 away from the solder joint 106 and on the welding area 101, and a single busbar portion 108 is in contact connection with a plurality of same-sex fine grids 104. In this way, a plurality of same-sex fine grids 104 located on the edge area 102 and not in contact connection with the pad 105 can all be in contact connection with the busbar portion 108, so that the busbar portion 108 can collect the current in a plurality of same-sex fine grids 104 located on the edge area 102 and not in contact connection with the pad 105, and finally transmit it to the pad 105.

[0057] In some cases, referring to Figure 6 , at least one busbar portion 108 may include a third end portion 118 close to the pad 105 and a fourth end portion 128 away from the pad 105. Along the first direction X, the width of the third end portion 118 is greater than the width of the fourth end portion 128.

[0058] On the one hand, the subsequent solder tape is in contact connection with the pad 105 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 105 is more likely to come into contact with the molten solder paste. Therefore, in the busbar portion 108, compared with the fourth end portion 128 away from the pad 105, the third end portion 118 close to the pad 105 is more likely to come into contact with the molten solder paste and have a breakage problem. Based on this, it is designed that along the first direction X, the width of the third end portion 118 is greater than the width of the fourth end portion 128, which helps to reduce the risk of breakage of the third end portion 118 affected by the molten solder paste based on the wider third end portion 118, so as to improve the structural stability of the busbar portion 108 itself.

[0059] On the other hand, compared with the central area 103 (referring to Figure 2 ), the edge area 102 (referring to Figure 2 ) is more likely to be subjected to greater external forces. Based on this, it is designed that along the first direction X, the width of the third end portion 118 is greater than the width of the fourth end portion 128, which is beneficial to increasing the contact area between the third end portion 118 and the pad 105 to improve the connection strength between the third end portion 118 and the pad 105, so as to reduce the risk of the third end portion 118 being disconnected from the pad 105 due to greater external forces.

[0060] On the other hand, the current collector 108 can collect the current in a plurality of same-sex fine grids 104 that are located on the edge region 102 and not in contact connection with the pads 105. Then, in the direction from the edge region 102 to the center region 103, the number of same-sex fine grids 104 electrically connected to the current collector 108 gradually increases, and the current collected in the current collector 108 gradually increases. Designing the third end portion 118 to have a larger width is beneficial to reducing the transmission resistance of the third end portion 118 itself and the contact area between the third end portion 118 and the pad 105, thereby reducing the transmission resistance on the path of the current transmitted from the current collector 108 to the pad 105 in multiple aspects, so as to improve the current collection ability of the current collector 108 to match the plurality of same-sex fine grids 104, thereby reducing the risk of overheating at the third end portion 118 of the current collector 108 due to excessive current aggregation, and improving the electrical performance and yield of the main-gridless back-contact battery.

[0061] In addition, designing the widths of different parts of the current collector 108 in the second direction Y in the first direction X to be different is beneficial to reasonably reducing the amount of raw materials required for preparing the current collector 108, thereby reducing the manufacturing cost of the main-gridless back-contact battery.

[0062] In some cases, continue to refer to Figure 6 , in the direction from the edge region 102 (refer to Figure 2 ) to the center region 103 (refer to Figure 2 ), the width of at least one current collector 108 in the first direction X gradually increases, then the transmission resistance of the current collector 108 itself gradually decreases, facilitating the collection of more current in the same-sex fine grids 104 along the way, so as to improve the current collection ability of the current collector 108, and is beneficial to reducing the risk of overheating in the region where the current collector 108 is close to the pad 105 due to excessive current aggregation, and improving the electrical performance and yield of the main-gridless back-contact battery.

[0063] It should be noted that a plurality of current collectors 108 are designed in a single main-gridless back-contact battery. As for the change in the width of different parts of any current collector 108 in the first direction X along the second direction Y, it can be adjusted according to actual needs. In the first direction X, designing the width of the third end portion 118 of any current collector 108 to be greater than the width of the fourth end portion 128 can improve the structural stability of the current collector 108 itself, improve the current collection ability of the current collector 108, and improve the connection strength between the third end portion 118 and the pad 105 to reduce the risk of disconnection between the third end portion 118 and the pad 105.

[0064] In some cases, refer to Figures 1 to 6, the number of the same-sex fine grids 104 in contact connection with a single bus bar 108 can be greater than the number of the same-sex fine grids 104 in contact connection with a single pad 105. In this way, when the pitch between any two adjacent same-sex fine grids 104 in the second direction Y is basically the same, it is beneficial to make the pad 105 located in the area of the edge region 102 close to the central region 103, avoiding the pad 105 being too close to the outer edge of the battery substrate 100, so as to avoid damage to the outer edge of the battery substrate 100 when the subsequent solder tape is in contact connection with the pad 105.

[0065] In some cases, referring to Figures 1 to 6 , in the second direction Y, the length of the connection line 107 can be less than the length of the bus bar 108. It should be noted that in the second direction Y, the length of the connection line 107 meets the requirement that the bending degree of the solder tape per unit length is relatively low, so as to ensure the stable connection between at least one solder joint 106 in contact connection with the connection line 107 and the solder tape. Then, the solder joints 106 not in contact connection with the connection line 107 can all be stably connected with the solder tape. Thus, while ensuring that the current in each same-sex fine grid 104 between two pads 105 facing each other in the second direction Y can be collected, the length of the connection line 107 can be reduced as much as possible to reduce the amount of raw materials required for preparing the connection line 107, thereby reducing the manufacturing cost of the main-gridless back-contact battery.

[0066] In some cases, referring to Figures 1 to 6 , in the cross-section perpendicular to the second direction Y, the cross-sectional area of the connection line 107 is smaller than the cross-sectional area of the bus bar 108.

[0067] It should be noted that the number of the same-sex fine grids 104 between the pad 105 and the solder joint 106 adjacent in the second direction Y is small, for example, it can be 0, so that the number of the same-sex fine grids 104 for which the connection line 107 needs to collect current is less than the number of the same-sex fine grids 104 on the edge region 102 for which the bus bar 108 needs to collect current. Therefore, compared with the current density transmitted by the connection line 107 to the pad 105, the current density transmitted by the bus bar 108 to the pad 105 is greater. Designing the cross-sectional area of the connection line 107 to be smaller than the cross-sectional area of the bus bar 108 is beneficial to further reduce the transmission resistance of the bus bar 108 itself, so as to collect the current in more same-sex fine grids 104 along the way, improve the current collection ability of the bus bar 108, and is beneficial to reducing the risk of overheating due to excessive current aggregation in the area of the bus bar 108 close to the pad 105, so as to improve the electrical performance and yield of the main-gridless back-contact battery.

[0068] In some embodiments, referring to Figures 1 to 6, on a cross-section perpendicular to the second direction Y, the cross-sectional area of the connection line 107 is the first area; on a cross-section perpendicular to the first direction X, the cross-sectional area of the homogeneous fine grid 104 is the second area; wherein, the first area can be greater than the second area. It should be noted that the connection line 107 needs to further transmit the current collected by the solder joint 106 from the homogeneous fine grid 104 to the pad 105 through itself, and further may need to transmit part of the current in the homogeneous fine grid 104 to the pad 105 through itself. Therefore, compared with the homogeneous fine grid 104, the connection line 107 needs to have a stronger current collection ability, and moreover, the connection line 107 needs to maintain good electrical contact performance with both the solder joint 106 and the pad 105. Based on this, designing the cross-sectional area of the connection line 107 to be greater than that of the homogeneous fine grid 104 is beneficial to reducing the transmission resistance of the connection line 107 itself, so as to improve the current collection effect, and is beneficial to reducing the risk of overheating due to excessive current aggregation in the connection line 107, and is beneficial to reducing the risk of disconnection between the connection line 107 and the solder joint 106 or the pad 105.

[0069] In some embodiments, referring to Figures 1 to 6 , the orthographic projection area of the pad 105 on the battery substrate 100 can be greater than the orthographic projection area of the solder joint 106 on the battery substrate 100, which is not only beneficial to reducing the transmission resistance of the pad 105 itself to improve the current collection ability of the pad 105, but also can improve the alignment accuracy and connection strength between the subsequent solder tape and the pad 105, and avoid the problem of virtual soldering or desoldering caused by excessive pressure of the solder tape on the pad 105 as the starting or ending soldering point, so as to improve the connection stability between the subsequent solder tape and the pad 105.

[0070] In some embodiments, referring to Figure 7 , Figure 7 is Figure 6 a partial cross-sectional schematic diagram of the main-gridless back-contact battery along the first cross-section direction AA1. Along the third direction Z, the thickness of the pad 105 is less than the thickness of the solder joint 106, and the third direction Z is the thickness direction of the battery substrate 100.

[0071] It should be noted that, generally speaking, the subsequent solder tape is in contact connection with the pad 105 serving as the starting or ending soldering point. For example, if more solder paste is required during soldering, the area of the solder tape opposite to the pad 105 will be raised due to the stacking of the solder paste. Based on this, by designing the thickness of the pad 105 to be smaller than that of the solder joint 106, when the part of the solder tape opposite to the pad 105 and the part of the solder tape opposite to the solder joint 106 are at the same height, when the solder tape is in contact connection with the solder joint 106, a certain spacing can also be reserved between the solder tape and the pad 105 to accommodate the stacked solder paste on the pad 105, which is beneficial to effectively avoid the problem of poor contact between the area of the solder tape opposite to the pad 105 and the pad 105 due to the stacking of the solder paste and raising, and is also beneficial to further reducing the bending degree of the solder tape. For example, it enables the solder tape to achieve electrical connection with both the pad 105 and the solder joint 106 without bending downward. In addition, designing the thickness of the pad 105 to be smaller can prevent the part of the solder tape opposite to the pad 105 from being raised too high by the solder paste relative to the battery substrate 100.

[0072] In some embodiments, referring to Figure 1 or Figure 2 , the number of solder joints 106 with which the connection lines 107 located on different welding areas 101 are in contact connection can be different. It should be noted that based on the different magnitudes of the external pressures received by different welding areas 101, the number of solder joints 106 with which the connection lines 107 provided on different welding areas 101 are in contact connection is designed to be different, so as to effectively reduce the risk that the solder joints 106 relatively close to the pad 105 have poor contact with the solder tape and cannot transmit current to the solder tape, and at the same time, reasonably control the length of the connection line 107 in the second direction Y to control the amount of raw materials required for preparing the connection line 107, thereby controlling the manufacturing cost of the back-contact battery without main grid.

[0073] In some cases, continuing to refer to Figure 1 or Figure 2 , compared with the welding area 101 that receives less external pressure, designing a larger number of solder joints 106 with which the connection line 107 is in contact connection on the welding area 101 that is prone to receiving greater external pressure is beneficial to reducing the risk of poor contact between the solder joint 106 and the solder tape caused by the greater external pressure, so that the connection line 107 can solve the problem that more solder joints 106 that are prone to being affected by external pressure and malfunction cannot collect current normally.

[0074] In some examples, continuing to refer to Figure 1 or Figure 2 , the battery substrate 100 may also have two edge areas 109 opposite to each other along the first direction X. The number of solder joints 106 with which the connection line 107 located on the welding area 101 closest to the edge area 109 is in contact connection is 3, and the number of solder joints 106 with which the connection line 107 located on other welding areas 101 is in contact connection is 1.

[0075] In some embodiments, with reference to Figure 2 , the battery substrate 100 may further have two edge regions 109 opposite to each other along the first direction X. The solder joint 106 located in the same welding region 101 and closest to the pad 105 is the target solder joint; the number of the same-sex fine grids 104 between the target solder joint on the two welding regions 101 closest to the edge region 109 and the pad 105 is the first number, and the number of the same-sex fine grids 104 between the target solder joint on the other welding regions 101 and the pad 105 is the second number, and the first number is less than the second number.

[0076] It should be noted that no solder joint 106 is provided on the same-sex fine grid 104 between the target solder joint and the pad 105. By designing the first number to be less than the second number, the number of solder joints 106 designed on the two welding regions 101 closest to the edge region 109 is more than the number of solder joints 106 designed on the other welding regions 101. This is beneficial to improving the connection stability between the solder tape and the pads 105 and solder joints 106 on the two welding regions 101 closest to the edge region 109 in the case where the two welding regions 101 closest to the edge region 109 are more vulnerable to greater external pressure, and reducing the number of solder joints 106 on the other welding regions 101 to reduce the manufacturing cost of the main-gridless back-contact battery.

[0077] In some examples, continuing to refer to Figure 2 , the number of the same-sex fine grids 104 between the target solder joint on the two welding regions 101 closest to the edge region 109 and the pad 105 is 0, and the number of the same-sex fine grids 104 between the target solder joint on the other welding regions 101 and the pad 105 is 3.

[0078] In summary, the pad 105 and the solder joint 106 located on the same welding area 101 are respectively located in the edge area 102 and the central area 103. The pad 105 can be regarded as the starting or ending point of soldering when the subsequent solder strip is in electrical contact with the main-gridless back-contact cell. On this basis, it is designed that at least two adjacent same-sex fine grids 104 are in contact connection with a single pad 105, and a single solder joint 106 is in contact connection with a single same-sex fine grid 104. On the one hand, it is beneficial to improve the current collecting effect of the pad 105, so that the current in more same-sex fine grids 104 can be transmitted to the pad 105 faster to establish a denser current collection network, thereby reducing the transmission distance of photo-generated carriers and reducing the series resistance of the main-gridless back-contact cell; on the other hand, as the starting or ending point of the subsequent solder strip, the size of the pad 105 connected to more same-sex fine grids 104 can be designed to be larger, which can not only reduce the transmission resistance of the pad 105 itself to match more same-sex fine grids 104, but also improve the alignment accuracy and connection strength between the subsequent solder strip and the pad 105, avoiding the problem of poor soldering or de-soldering caused by excessive pressure of the solder strip on the pad 105 as the starting or ending point, thereby contributing to the improvement of the current collection efficiency of the pad 105 and the connection stability between the subsequent solder strip and the pad 105. Overall, it is beneficial to improve the current collection efficiency of the main-gridless back-contact cell and the photoelectric conversion efficiency of the main-gridless back-contact cell.

[0079] Further, in combination with the design of the connection line 107, the pad 105 and at least one solder joint 106 close to the pad 105 along the second direction Y can be electrically connected by means of the connection line 107. In other words, the connection line 107 can electrically connect the solder joint 106, which is prone to problems such as poor soldering, solder leakage or de-soldering with the subsequent solder strip, near the pad 105 to the pad 105. Even if the solder joint 106 close to the pad 105 has poor contact with the solder strip and cannot transmit the current to the solder strip, the solder joint 106 can directly transmit the current to the pad 105 through the connection line 107 and then transmit it to the solder strip. Therefore, the design of the connection line 107 is beneficial to further ensure that the subsequent solder strip can collect the current in all same-sex fine grids, so as to further improve the photoelectric conversion efficiency of the main-gridless back-contact cell.

[0080] Another embodiment of the present disclosure provides a photovoltaic module, which is formed by connecting multiple back-contact cells provided in the foregoing embodiments, or by connecting back-contact cells formed by the preparation methods provided in the foregoing embodiments. The following will describe the photovoltaic module provided in another embodiment of the present disclosure 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 described in detail here.

[0081] Combined with reference Figure 8 、 Figure 9 and Figures 1 to 7, the photovoltaic module includes: a battery string formed by connecting a plurality of the back-contact cells 40 without main grid provided by 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.

[0082] Among them, Figure 8 A partial three-dimensional schematic diagram of a photovoltaic module provided by another embodiment of the present disclosure, Figure 9 is Figure 8 A partial cross-sectional schematic diagram of the photovoltaic module shown along the second cross-section direction BB1.

[0083] In some embodiments, the back-contact cell 40 without main grid 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 BackContact), or an HPBC cell (Hybrid Passivated Back Contact), etc. In addition, the back-contact cells 40 without main grid 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 without main grid can be a whole piece of cell or a sliced cell, and the sliced cell refers to a cell formed by cutting a complete whole piece of cell through a cutting process.

[0084] In some embodiments, referring to Figure 8 or Figure 9 , the plurality of back-contact cells 40 without main grid can be electrically connected through a conductive strip 43. Figure 8 and Figure 9 Only shows a positional relationship between a plurality of back-contact cells 40 without main grid. In actual application, the grid lines of adjacent back-contact cells without main grid can also be located on different sides respectively, and the conductive strip connects different sides of two adjacent back-contact cells without main grid.

[0085] 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 main-gridless back-contact battery 40, and the second encapsulation layer covers the other of the front or back surfaces of the main-gridless 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 copolymer (POE) film, or a polyethylene terephthalate (PET) film. Alternatively, 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 co-extruded film can be prepared by extruding one or more raw materials onto another film that has already been made during the film processing, or by bonding different types of films that have already been made together.

[0086] In some cases, there is a demarcation line between the first encapsulation layer and the second encapsulation layer before lamination. After the lamination process, there will no longer be the concept of the first encapsulation layer and the second encapsulation layer in the formed photovoltaic module, that is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0087] 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 velvet surface including a plurality of convex 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.

[0088] In some cases, the surface of the main-gridless back-contact battery 40 has a plurality of fine grids arranged at intervals in the second direction. During the process of constructing a battery string using the main-gridless back-contact battery 40, the conductive band 43 is electrically connected to the plurality of fine grids on each of the two adjacent main-gridless back-contact batteries 40.

[0089] 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 to them 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 changes and modifications 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 shall be subject to the scope defined by the claims.

Claims

1. A busbar-free back contact battery, characterized in that: include: A battery substrate, wherein the battery substrate has a first welding area and a second welding area alternately arranged along a first direction, and further has two edge areas opposite to 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 located on the battery substrate and arranged alternately 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 pad is located in the welding area on the edge area, and a single pad is contacted and connected with at least two adjacent fine grids of the same sex; A soldering point is located in the central area of ​​the soldering area, a single soldering point is in contact with a single fine grid of the same sex, and there are M fine grids of the same sex between the soldering pad and the soldering point adjacent to each other along the second direction, where M is an integer greater than or equal to 0; The connection line connected to the pad is also connected to at least one soldering point close to the pad along the second direction, and each of the fine grids of the same sex between two opposite connection lines along the second direction has one soldering point; Wherein, the welding area is the first welding area and the isotropic fine grid is the first fine grid, and / or the welding area is the second welding area and the isotropic fine grid is the second fine grid.

2. The busbar-free back contact cell according to claim 1, characterized in that: There are multiple connection lines that are in contact with the same pad, and each of the multiple connection lines is in contact with at least one soldering point close to the pad.

3. The busbar-free back contact cell according to claim 1 or 2, characterized in that: At least one of the connecting lines includes a first end close to the pad and a second end close to the solder joint, and along the first direction, a width of the first end is greater than a width of the second end.

4. The busbar-free back contact cell according to claim 1, characterized in that: Also includes: The busbar is located at a side of the pad away from the soldering point and on the soldering area. A single busbar contacts and connects a plurality of fine grids of the same sex.

5. The busbar-free back contact cell according to claim 4, characterized in that: The number of the fine grids of the same sex that are contact-connected to a single bus bar is greater than the number of the fine grids of the same sex that are contact-connected to a single pad.

6. The busbar-free back contact cell according to claim 4, characterized in that: Along the second direction, the length of the connecting line is smaller than the length of the confluence portion; and / or, 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 confluence portion.

7. The busbar-free back contact cell according to claim 1 or 6, characterized in that: In a cross section perpendicular to the second direction, the cross-sectional area of ​​the connecting line is a first area; in 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.

8. The busbar-free back contact cell according to claim 1, characterized in that: The orthographic projection area of ​​the solder pad on the battery substrate is larger than the orthographic projection area of ​​the solder joint on the battery substrate; and / or, along the third direction, the thickness of the solder pad is smaller than the thickness of the solder joint.

9. The busbar-free back contact cell according to claim 1, characterized in that: The numbers of the welding points connected by the connection wires located on different welding areas are different.

10. A photovoltaic module, characterized in that: include: A battery string, formed by connecting a plurality of busbar-free back-contact batteries as claimed in any one of claims 1 to 9; A packaging film, used to cover the surface of the battery string; The cover plate is used to cover the surface of the packaging film away from the battery string.

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