Back contact battery and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a back contact battery and a photovoltaic module, the back contact battery comprises first and second main grids which are alternately arranged along a first direction, the first main grid comprises a plurality of first parts which are arranged at intervals along a second direction, and the second main grid comprises a plurality of second parts which are arranged at intervals along the second direction; the first penetrating line extends along the first direction and is in contact connection with the plurality of first parts in the same row along the first direction; the second penetrating lines extend in the first direction and are in contact connection with the multiple second parts located in the same row in the first direction; the adjacent first and second through lines form a through line group, the number of the through line groups is reduced along with the increase of the number of the main grids, in the second direction, the width of at least one of the first and second through lines is reduced along with the increase of the number of the main grids, and the number of the main grids is the sum of the number of the first and second main grids, so that the electrical performance of the back contact battery is improved at least; and the preparation cost of the back contact battery is reduced.

Description

Technical Field

[0001] The present disclosure relates to the photovoltaic field, and in particular to a back-contact cell and a photovoltaic module. Background Art

[0002] An interdigitated back contact (IBC) cell is a back-junction back contact photovoltaic cell, in which the positive and negative electrodes are arranged in an interdigitated manner on the backlight side of the photovoltaic cell. The light-receiving side of the cell is not blocked by any metal electrode, which effectively increases the short-circuit current of the photovoltaic cell. Multiple photovoltaic cells are electrically connected through welding strips to form a photovoltaic module. The current generated in the photovoltaic cell is first collected through the fine grid, then collected through the main grid electrically connected to the fine grid, and then collected through the welding strip electrically connected to the main grid.

[0003] However, different main grids are electrically connected to different welding strips, and different welding strips are also spaced apart from each other. Therefore, the welding strips have a relatively single path for collecting the current generated in the IBC battery, and can only collect the current from different main grids. If the fine grid and / or main grid in a local area of ​​the IBC battery fails, the current cannot be effectively collected, which may easily cause a large difference in current size between the local area and other areas of the IBC battery, and easily cause a hot spot effect at the location where the local failure occurs, thereby reducing the photoelectric conversion efficiency of the IBC battery.

[0004] Therefore, the electrical performance of back-contact batteries needs to be further improved. Summary of the invention

[0005] The embodiments of the present disclosure provide a back-contact cell and a photovoltaic module, which are at least beneficial to improving the electrical performance of the back-contact cell and reducing the preparation cost of the back-contact cell.

[0006] According to some embodiments of the present disclosure, on the one hand, the embodiments of the present disclosure provide a back-contact battery, comprising: a battery substrate; a first main grid and a second main grid located on the battery substrate and alternately arranged along a first direction, the first main grid comprising a plurality of first portions spaced apart along a second direction, and the second main grid comprising a plurality of second portions spaced apart along the second direction; a first through-line extending along the first direction, being in contact and connected with a plurality of the first portions in the same row along the first direction; a second through-line extending along the first direction, being in contact and connected with a plurality of the second portions in the same row along the first direction; adjacent first through-lines and second through-lines serve as a through-line group, the number of the through-line groups decreases as the number of the main grids increases, and along the second direction, the width of at least one of the first through-lines and the second through-lines decreases as the number of the main grids increases, and the number of the main grids is the sum of the number of the first main grids and the number of the second main grids.

[0007] In some embodiments, the number of main gates is less than a first threshold, and the number of through-line groups is greater than a first preset value; or, the number of main gates is greater than or equal to a first threshold, and the number of through-line groups is less than a second preset value; wherein the first preset value is greater than the second preset value.

[0008] In some embodiments, the back-contact battery further includes: a first fine grid and a second fine grid located on the battery substrate and alternately arranged along the second direction, the second fine grid being disconnected at the first main grid, the first fine grid being disconnected at the second main grid, the disconnected portion of the second fine grid being used for the first main grid to be contacted and connected with a plurality of the first fine grids along the second direction, and the disconnected portion of the first fine grid being used for the second main grid to be contacted and connected with a plurality of the second fine grids along the second direction; the number of main grids is less than a first threshold value, and along the second direction, the ratio of the width of at least one of the first penetration line and the second penetration line to the width of the fine grid is within a first preset range; or, the number of main grids is greater than or equal to the first threshold value, and along the second direction, the ratio of the width of at least one of the first penetration line and the second penetration line to the width of the fine grid is within a second preset range; wherein the minimum value of the first preset range is greater than the minimum value of the second preset range, the maximum value of the first preset range is greater than the maximum value of the second preset range, and the fine grids include the first fine grid and the second fine grid.

[0009] In some embodiments, the battery substrate is divided into 1 / N whole battery sheets, N is a positive integer greater than 1; the battery substrate includes a first edge area, a center area and a second edge area arranged in sequence along the second direction, and at least part of the first edge area of ​​the battery substrate is located at the edge of the whole battery sheet; the back contact battery also includes: a third penetration line located on the first edge area and extending along the first direction; a fourth penetration line located on the second edge area and extending along the first direction; wherein, one of the plurality of first portions and the plurality of second portions located on the first edge area and in the same line along the first direction is in contact with the third penetration line, and the other is in contact with the first penetration line or the second penetration line; one of the plurality of first portions and the plurality of second portions located on the second edge area and in the same line along the first direction is in contact with the fourth penetration line, and the other is in contact with the first penetration line or the second penetration line; along the second direction, the spacing between the third penetration line and the nearest penetration line group is a first spacing, and the spacing between adjacent penetration line groups is a second spacing, and the first spacing is smaller than the second spacing.

[0010] In some embodiments, on at least a portion of the battery substrate, the spacing between different adjacent through-line groups gradually increases in a direction from the first edge region to the central region.

[0011] In some embodiments, among the three adjacent groups of through line groups along the second direction, the ratio of the spacing between two adjacent groups of through line groups farther away from the first edge area to the spacing between two adjacent groups of through line groups closer to the first edge area is 1-2.

[0012] In some embodiments, the distance between the fourth penetration line and the penetration line group closest thereto is a third distance, and on at least a portion of the battery substrate, the third distance is greater than the second distance.

[0013] In some embodiments, the back-contact battery further includes: a plurality of first pads, each of the first portions being in contact with at least one of the first pads; a plurality of second pads, each of the second portions being in contact with at least one of the second pads; and on at least a portion of the battery substrate, in a direction from the first edge region to the center region, the number of the first pads located between different adjacent groups of through-wires gradually increases, and / or the number of the second pads located between different adjacent groups of through-wires gradually increases.

[0014] In some embodiments, the battery substrate includes a substrate and a passivation layer located on a surface of the substrate, and the first through-wire and the second through-wire are partially embedded in the passivation layer.

[0015] According to some embodiments of the present disclosure, on the other hand, the embodiments of the present disclosure further provide a photovoltaic module, comprising: a battery string, the battery string is formed by connecting a plurality of back-contact batteries as described in any one of the above items; a packaging film, the packaging film covers the battery string; and a cover plate, the cover plate is located on a side of the packaging film away from the battery string.

[0016] The technical solution provided by the embodiments of the present disclosure has at least the following advantages: When the overall layout area on the back contact battery remains unchanged, after the number of main grids increases, when a fault occurs in at least a local area on a first main grid or a second main grid, the impact on the entire back contact battery will be weakened. Based on this, designing a small number of through-wire groups can produce a good current-sharing effect on the entire back contact battery, which is sufficient to effectively improve the electrical performance of the back contact battery and improve the anti-hot spot performance of the back contact battery. Vice versa, after the number of main grids decreases, when a fault occurs in at least a local area on a first main grid or a second main grid, the impact on the entire back contact battery will increase, and more groups of through-wire groups need to be designed to reduce the impact of the fault on the entire back contact battery, so as to ensure a good current-sharing effect on the entire back contact battery and ensure good anti-hot spot performance of the back contact battery. Therefore, on the basis of designing the through-wire group, the number of through-wire groups is designed to decrease as the number of main grids increases, which is beneficial to reduce the probability of hot spot effects in the back contact battery and improve the electrical performance with the help of the through-wire group, while reducing the cost required to prepare the first main grid, the second main grid and the through-wire group. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings, and these exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the traditional technology, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A first partial top view schematic diagram of a back contact battery provided by an embodiment of the present disclosure; Figure 2 A second partial top view schematic diagram of a back contact battery provided in one embodiment of the present disclosure; Figure 3 A partial top view schematic diagram of a single first main grid in a back contact battery provided by an embodiment of the present disclosure; Figure 4 A partial top view schematic diagram of a single second main grid in a back contact battery provided by an embodiment of the present disclosure; Figure 5 A third partial top view schematic diagram of a back contact battery provided in one embodiment of the present disclosure; Figure 6 for Figure 1 A partial cross-sectional schematic diagram of the back contact battery shown along the first cross-sectional direction AA1; Figure 7 A partial three-dimensional schematic diagram of a photovoltaic assembly provided by another embodiment of the present disclosure; Figure 8 for Figure 7 A schematic partial cross-sectional view along the second cross-sectional direction BB1. DETAILED DESCRIPTION

[0019] As can be seen from the background technology, the electrical performance of back-contact batteries needs to be improved.

[0020] After analysis, it was found that in the IBC battery, the currents on different same-polarity main grids, such as different positive main grids, are collected by different welding strips, and the currents collected on different same-polarity main grids and their corresponding welding strips have no paths for mutual flow. If a local area of ​​the IBC battery, such as a local area of ​​a main grid, fails and cannot effectively collect current, the current actually collected on the main grid is smaller than the ideal state, resulting in a large difference between the actual current on the main grid and the actual current on other same-polarity main grids, thereby reducing the uniformity of current transmission on the battery cell as a whole, causing the faulty area on the battery cell to heat up and generate more heat, causing a hot spot effect, thereby reducing the photoelectric conversion efficiency of the IBC battery and reducing the uniformity of the overall photoelectric conversion efficiency of the IBC battery.

[0021] The present disclosure provides a back contact cell and a photovoltaic module. In the back contact cell, when the overall layout area on the back contact cell remains unchanged, after the number of main grids increases, when a fault occurs in at least a local area on a first main grid or a second main grid, the impact on the entire back contact cell will be weakened. Based on this, a small number of through-wire groups can be designed to produce a good current balancing effect on the entire back contact cell, which is sufficient to effectively improve the electrical performance of the back contact cell and improve the anti-hot spot performance of the back contact cell. Vice versa, after the number of main grids decreases, when a fault occurs in at least a local area on a first main grid or a second main grid, the impact on the entire back contact cell will increase, and more groups of through-wire groups need to be designed to reduce the impact of the fault on the entire back contact cell, so as to ensure a good current balancing effect on the entire back contact cell and ensure good anti-hot spot performance of the back contact cell. Therefore, on the basis of designing the through-wire group, the number of through-wire groups is designed to decrease as the number of main grids increases, which is beneficial to reduce the probability of hot spot effect on the back contact cell and improve the electrical performance with the help of the through-wire group, while reducing the cost required to prepare the first main grid, the second main grid and the through-wire group.

[0022] In the description of the embodiments of the present disclosure, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] In the description of the embodiments of the present disclosure, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0025] In the description of the embodiments of the present disclosure, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0026] In the description of the embodiments of the present disclosure, the orientations or positional relationships indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description. They do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure.

[0027] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to the specific circumstances.

[0028] In the accompanying drawings corresponding to the embodiments of the present disclosure, the thickness and area of ​​the layers are exaggerated for better understanding and ease of description. When describing a component (such as a layer, film, region or substrate) on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may exist between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component as being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a partial edge of the entire surface.

[0029] In the description of the embodiments of the present disclosure, when a component "includes" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it may be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may exist in between. In addition, when a component such as a layer, film, region, or plate is "directly located on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located in between.

[0030] The terms used in the description of the various embodiments described herein are only used to describe specific embodiments and are not intended to be limiting. As used in the description of the various embodiments described and in the appended claims, "the components" are also intended to include plural forms unless the context clearly indicates otherwise. Among them, components include components such as layers, films, regions, or plates.

[0031] The following will describe the various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present disclosure, many technical details are provided in order to enable the reader to better understand the embodiments of the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the embodiments of the present disclosure can be implemented.

[0032] An embodiment of the present disclosure provides a back-contact battery, which will be described in detail below with reference to the accompanying drawings.

[0033] Combined with reference Figures 1 to 4The back-contact battery includes: a battery substrate 101; a first main grid 102 and a second main grid 103 located on the battery substrate 101 and alternately arranged along a first direction X, the first main grid 102 includes a plurality of first portions 112 spaced apart along a second direction Y, and the second main grid 103 includes a plurality of second portions 113 spaced apart along the second direction Y; a first through-line 104 extending along the first direction X is in contact and connection with the plurality of first portions 112 in the same row along the first direction X; a second through-line 105 extending along the first direction X is in contact and connection with the plurality of second portions 113 in the same row along the first direction X.

[0034] Further, combined with reference Figure 1 and Figure 2 , the adjacent first through-line 104 and the second through-line 105 are regarded as a through-line group 45, the number of the through-line group 45 decreases as the number of main grids increases, and along the second direction Y, the width of at least one of the first through-line 104 and the second through-line 105 decreases as the number of main grids increases, and the number of main grids is the sum of the number of first main grids 102 and the number of second main grids 103.

[0035] in, Figure 1 A first partial top view schematic diagram of a back contact battery provided by an embodiment of the present disclosure; Figure 2 A second partial top view schematic diagram of a back contact battery provided in one embodiment of the present disclosure; Figure 3 A partial top view schematic diagram of a single first main grid in a back contact battery provided by an embodiment of the present disclosure; Figure 4 A partial top view of a single second main grid in a back contact battery provided by an embodiment of the present disclosure. It should be noted that, in order to facilitate the distinction between the first main grid 102 and the second main grid 103, Figure 1 and Figure 2 In the figure, the first main grid 102 and the second main grid 103 are drawn using different filling methods.

[0036] It is worth emphasizing that the comparison reference Figure 1 and Figure 2, when the overall layout area on the back contact battery remains unchanged, after the number of main grids increases, the current shared on each first main grid 102 and the current shared on each second main grid 103 will both decrease. When a fault occurs in at least a local area on a first main grid 102 or a second main grid 103, the impact on the entire back contact battery will be weakened. Based on this, designing a small number of through-wire groups 45 can produce a good current-sharing effect on the entire back contact battery, which is sufficient to effectively improve the electrical performance of the back contact battery and the anti-hot spot performance of the back contact battery. Vice versa, after the number of main grids decreases, the current shared on each first main grid 102 and the current shared on each second main grid 103 will both increase. When a fault occurs in at least a local area on a first main grid 102 or a second main grid 103, the impact on the entire back contact battery will increase. It is necessary to design more through-wire groups 45 to reduce the impact of the fault on the entire back contact battery, so as to ensure a good current-sharing effect on the entire back contact battery and ensure a good anti-hot spot performance of the back contact battery. Moreover, no matter the number of main grids or the number of through-line groups 45 increases, the manufacturing cost of the back contact cell will increase.

[0037] Therefore, on the basis of designing the through line group 45, the number of through line groups 45 is designed to decrease as the number of main grids increases. This is beneficial for reducing the probability of hot spot effect in the back contact battery and improving the electrical performance with the help of the through line group 45, while reducing the cost required to prepare the first main grid 102, the second main grid 103 and the through line group 45, so as to balance the improvement of the electrical performance of the back contact battery and the reduction of the preparation cost.

[0038] The following is a detailed description of how the through-line group 45 can produce a good current-sharing effect on the entire back-contact battery to improve the electrical performance of the back-contact battery.

[0039] It is worth noting that the first penetration line 104 can electrically connect multiple first portions 112 in the same row along the first direction X at the same time, so that the multiple first portions 112 are electrically connected to each other, and the current on the multiple first portions 112 can have multiple flow paths based on the first penetration line 104. Moreover, the multiple first portions 112 in the same row along the first direction X belong to different first main grids 102 respectively. In other words, different first portions 112 in the multiple first portions 112 in the same row along the first direction X correspond to different sub-components of the first main grid 102. In this way, by means of the first penetration line 104, the multiple first portions 112 in the same row along the first direction X are electrically connected at the same time, so that the multiple first main grids 102 arranged at intervals along the first direction X can be interconnected with each other to form a more dense current transmission path, and the first penetration line 104 makes the first portions 112 in the same row along the first direction X at the same potential, that is, effectively avoid the potential difference between the first portions 112 in the same row along the first direction X.

[0040] In addition, in the same first main grid 102, at least a part of the different first parts 112 are respectively contacted and connected with different first penetration wires 104. When a plurality of back contact batteries are subsequently connected by a welding strip, different first penetration wires 104 will be electrically connected to the same welding strip, so that different first penetration wires 104 are also interconnected with each other, further forming a more dense current transmission path, and different first penetration wires 104 are also at the same potential with the help of the welding strip, that is, the potential difference between different first penetration wires 104 is effectively avoided. In this way, even if the first main grid 102 is disconnected into multiple first parts 112, multiple first penetration wires 104 can be electrically connected as a whole, so that multiple first main grids 102 are at the same potential. Based on this, even if a partial area of ​​the first main grid 102 fails, with the help of the connection of the first penetration wire 104, the current on the multiple first main grids 102 can be equalized again, so that the multiple first main grids 102 are at the same potential again, thereby effectively avoiding the phenomenon of heating due to local area failure.

[0041] Similarly, the second penetration line 105 can electrically connect multiple second portions 113 in the same row along the first direction X at the same time, so that the multiple second portions 113 are electrically connected to each other, and the current on the multiple second portions 113 can have multiple flow paths based on the second penetration line 105. Moreover, the multiple second portions 113 in the same row along the first direction X belong to different second main grids 103 respectively. In other words, different second portions 113 in the multiple second portions 113 in the same row along the first direction X correspond to different sub-components of the second main grid 103. In this way, by means of the second penetration line 105, the multiple second portions 113 in the same row along the first direction X are electrically connected at the same time, so that the multiple second main grids 103 arranged at intervals along the first direction X can be interconnected with each other to form a more dense current transmission path, and the second penetration line 105 makes the second portions 113 in the same row along the first direction X at the same potential, that is, effectively avoid the potential difference between the second portions 113 in the same row along the first direction X.

[0042] In addition, in the same second main grid 103, at least a part of the different second parts 113 are respectively contacted and connected with different second through-wires 105. When a plurality of back-contact batteries are subsequently connected by a welding strip, different second through-wires 105 will be electrically connected to the same welding strip, so that different second through-wires 105 are also interconnected with each other, further forming a denser current transmission path, and different second through-wires 105 are also at the same potential by means of the welding strip, that is, the potential difference between different second through-wires 105 is effectively avoided. In this way, even if the second main grid 103 is disconnected into a plurality of second parts 113, the plurality of second main grids 103 can be electrically connected as a whole by means of a plurality of second through-wires 105, so that the plurality of second main grids 103 are at the same potential. Based on this, even if a partial area of ​​the second main grid 103 fails, the current on the plurality of second main grids 103 can be equalized again by means of the connection of the second through-wires 105, so that the plurality of second main grids 103 are at the same potential again, thereby effectively avoiding the phenomenon of heating due to failure in a local area.

[0043] Therefore, the design of the through-wire group 45 including the adjacent first through-wires 104 and second through-wires 105 is beneficial to interconnecting the plurality of first main grids 102 as a whole, and to interconnecting the plurality of second main grids 103 as a whole, and to ensure the insulation between the first main grids 102 and the second main grids 103. In this way, even if a local area of ​​the back contact battery fails and the current cannot be effectively collected, resulting in the actual current collected in the local area where the failure occurs being smaller than the ideal state, based on the effect of the through-wire group 45, the current can be uniformly circulated on the plurality of first main grids 102 and the plurality of second main grids 103 again, so as to improve the overall electrical performance of the back contact battery, such as the uniformity of the current density, thereby improving the uniformity of the overall photoelectric conversion efficiency of the back contact battery, and avoiding the problem of local heating caused by the excessive difference in current between different areas on the back contact battery sheet, so as to improve the anti-hot spot performance of the back contact battery.

[0044] It should be noted that local area failures of the back-contact battery include but are not limited to the following situations: in some cases, at least one first main grid 102 or at least one second main grid 103 is at least partially faulty, such as dimensional changes or broken grids caused by printing accuracy; in other cases, the material constituting the substrate in the back-contact battery itself has certain defects, such as differences in surface defects in different areas of the substrate; in some other cases, the light intensity received by different areas of the back-contact battery is greatly different, for example, part of the back-contact battery is blocked.

[0045] It is worth noting that reference Figure 3, designing the first main grid 102 to include a plurality of first portions 112 spaced apart along the second direction Y can be regarded as breaking the first main grid 102 into a plurality of segments along the second direction Y, each segment being a first portion 112; referring to Figure 4 , designing the second main grid 103 to include a plurality of second portions 113 spaced apart along the second direction Y can be regarded as breaking the second main grid 103 into a plurality of segments along the second direction Y, each segment being a second portion 113. Figures 1 to 4 The disconnected portion of the first main grid 102, i.e., the interval between adjacent first portions 112 along the second direction Y, is used for the second penetration line 105 to penetrate; the disconnected portion of the second main grid 103, i.e., the interval between adjacent second portions 113 along the second direction Y, is used for the first penetration line 104 to penetrate.

[0046] The back contact battery provided by one embodiment of the present disclosure is described in detail below.

[0047] In some embodiments, in conjunction with reference Figures 1 to 4 , the number of busbars is less than the first threshold value, and the number of through-line groups 45 is greater than the first preset value; or, the number of busbars is greater than or equal to the first threshold value, and the number of through-line groups 45 is less than the second preset value; wherein the first preset value is greater than the second preset value. In other words, when designing the number of busbars and the number of through-line groups 45 on the back-contact battery, a first threshold value is set for the number of busbars. Compared with the case where the number of busbars is greater than or equal to the first threshold value, when the number of busbars is less than the first threshold value, the number of through-line groups 45 is greater. With the help of the through-line groups 45 with more numbers, the influence on the current uniformity on the back-contact battery sheet when some busbars fail is reduced, thereby ensuring that the back-contact battery has good electrical performance.

[0048] It should be noted that the failure of part of the main grid includes but is not limited to the following situations: the main grid is broken, i.e., the main grid is broken; or the substrate facing the main grid has a large surface defect; or the area where the main grid is located is blocked and the light intensity is significantly reduced. The main grid includes the first main grid 102 or the second main grid 103. In addition, Figure 1 and Figure 2 All of them are partial top views of back-contact batteries. For the sake of clarity, Figure 1 and Figure 2 Although the left and right sides of the battery substrate 101 along the first direction X are schematically shown, all the first main grids 102 and all the second main grids 103 on the battery substrate 101 are not schematically shown.

[0049] In some examples, the first threshold may be 18, 19, 20, or 21, etc., the first preset value may be 4, 5, or 6, etc., and the second preset value may be 2, 3, or 4, etc.

[0050] In one example, the first threshold may be 20, the first preset value may be 5, etc., and the second preset value may be 3. In other words, when the number of main grids is less than 20, 5 sets of through-line groups 45 are designed; when the number of main grids is greater than or equal to 20, 3 sets of through-line groups 45 are designed.

[0051] In some embodiments, in conjunction with reference Figures 1 to 4 The back-contact battery may also include: first fine grids 106 and second fine grids 107 located on the battery substrate 101 and alternately arranged along the second direction Y, the second fine grids 107 are disconnected at the first main grid 102, the first fine grids 106 are disconnected at the second main grid 103, the disconnected portion of the second fine grids 107 is used for the first main grid 102 to contact and connect with multiple first fine grids 106 along the second direction Y, and the disconnected portion of the first fine grids 106 is used for the second main grid 103 to contact and connect with multiple second fine grids 107 along the second direction Y.

[0052] On this basis, the design of the correlation between the number of main gates and the widths of the first through line 104, the second through line 105 and the fine gate in the second direction Y can be divided into at least the following two cases: in some cases, the number of main gates is less than the first threshold value, and along the second direction Y, the ratio of the width of at least one of the first through line 104 and the second through line 105 to the width of the fine gate is in a first preset range; in other cases, the number of main gates is greater than or equal to the first threshold value, and along the second direction Y, the ratio of the width of at least one of the first through line 104 and the second through line 105 to the width of the fine gate is in a second preset range.

[0053] The minimum value of the first preset range is greater than the minimum value of the second preset range, the maximum value of the first preset range is greater than the maximum value of the second preset range, and the fine gate includes a first fine gate 106 and a second fine gate 107 .

[0054] It should be noted that, in order to distinguish the first fine gate 106 from the second fine gate 107, Figure 1 and Figure 2 In the figures, the first fine gate 106 is indicated by a solid line, and the second fine gate 107 is indicated by a dotted line.

[0055] It is worth noting that when the number of main gates is less than the first threshold, the ratio of the width of at least one of the first through-line 104 and the second through-line 105 to the width of the fine gate along the second direction Y is taken as the first ratio; when the number of main gates is greater than or equal to the first threshold, the ratio of the width of at least one of the first through-line 104 and the second through-line 105 to the width of the fine gate along the second direction Y is taken as the second ratio. Based on this, the purpose of designing the minimum value of the first preset range to be greater than the minimum value of the second preset range, and the maximum value of the first preset range to be greater than the maximum value of the second preset range is to design the first ratio to be greater than the second ratio.

[0056] In other words, the width of the fine gate is a fixed reference value. Compared with the case where the number of main gates is greater than or equal to the first threshold value, when the number of main gates is less than the first threshold value, along the second direction Y, the ratio of the width of at least one of the first through-line 104 and the second through-line 105 to the width of the fine gate is designed to be larger, and the width of the first through-line 104 and / or the second through-line 105 is larger, which is conducive to further reducing the transmission resistance of the first through-line 104 and the contact resistance between the first through-line 104 and the first portion 112, so as to reduce the transmission resistance of the current between the first portion 112 and the first through-line 104. Resistance, so as to enhance the ability of the single first portion 112 to collect carriers in a larger area on the battery substrate 101, and reduce the current loss caused by the transmission resistance as much as possible; and / or, it is beneficial to further reduce the transmission resistance of the second through-line 105 and the contact resistance between the second through-line 105 and the second portion 113, so as to reduce the transmission resistance of the current between the second portion 113 and the second through-line 105, so as to enhance the ability of the single second portion 113 to collect carriers in a larger area on the battery substrate 101, and reduce the current loss caused by the transmission resistance as much as possible.

[0057] In some cases, compared with the case where the number of main gates is greater than or equal to the first threshold, along the second direction Y, when the number of main gates is less than the first threshold, along the second direction Y, only the ratio of the width of the first through line 104 to the width of the fine gate can be designed to be larger, that is, the second through line 105 with the same width can be designed regardless of the number of main gates; in other cases, compared with the case where the number of main gates is greater than or equal to the first threshold, along the second direction Y, when the number of main gates is less than the first threshold, along the second direction Y, only the ratio of the width of the second through line 105 to the width of the fine gate can be designed to be larger, that is, the first through line 104 with the same width can be designed regardless of the number of main gates; in some other cases, compared with the case where the number of main gates is greater than or equal to the first threshold, along the second direction Y, when the number of main gates is less than the first threshold, along the second direction Y, the ratio of the width of the first through line 104 to the width of the fine gate can be designed to be larger, and the ratio of the width of the second through line 105 to the width of the fine gate can be larger.

[0058] In some examples, the first threshold value may be 18, 19, 20, or 21, etc.; the first preset range may be 2 to 20, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19, etc.; the second preset range may be 1.5 to 15, for example, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, or 14.5, etc.

[0059] In some embodiments, reference Figure 1 , Figure 2 or Figure 5 , Figure 5 A third partial top view schematic diagram of a back-contact battery provided in an embodiment of the present disclosure, wherein the battery substrate 101 may be composed of 1 / N whole battery cells 100, where N is a positive integer greater than 1; the battery substrate 101 includes a first edge region 111, a center region 121, and a second edge region 131 arranged in sequence along a second direction Y, and the first edge region 111 of at least part of the battery substrate 101 is located at the edge of the whole battery cell 100.

[0060] It should be noted that Figure 1 and Figure 2 It can be regarded as an example that a single back contact battery includes one battery substrate 101. Figure 5 It can be regarded as an example that a single back contact battery includes two battery substrates 101. In addition, in order to distinguish the first main grid 102 and the second main grid 103, Figure 5 Different filling methods are also used to draw the first main grid 102 and the second main grid 103; and, Figure 1 , Figure 2 and Figure 5 In the figure, the first fine grid 106 is indicated by a thin solid line, and the second fine grid 107 is indicated by a thin dotted line; Figure 1 , Figure 2 and Figure 5 In the figure, the first penetration line 104 is indicated by a thicker solid line, and the second penetration line 105 is indicated by a thicker dotted line.

[0061] Based on this, continue to refer to Figure 1 , Figure 2 or Figure 5 The back contact battery may further include: a third penetration line 108 located on the first edge area 111 and extending along the first direction X; a fourth penetration line 109 located on the second edge area 131 and extending along the first direction X; wherein, one of the plurality of first portions 112 and the plurality of second portions 113 located on the first edge area 111 and in the same row along the first direction X is in contact with the third penetration line 108, and the other is in contact with the first penetration line 104 or the second penetration line 105; one of the plurality of first portions 112 and the plurality of second portions 113 located on the second edge area 131 and in the same row along the first direction X is in contact with the fourth penetration line 109, and the other is in contact with the first penetration line 104 or the second penetration line 105; along the second direction Y, the spacing between the third penetration line 108 and the penetration line group 45 closest to it is the first spacing, the spacing between adjacent penetration line groups 45 is the second spacing, and the first spacing is smaller than the second spacing.

[0062] It should be noted that Figure 1 , Figure 2and Figure 5 In the examples, the plurality of second portions 113 located on the first edge region 111 and in the same row along the first direction X are connected to the third penetration line 108, and the plurality of first portions 112 located on the first edge region 111 and in the same row along the first direction X are connected to the first penetration line 104. In other words, the third penetration line 108 has a different polarity from the first penetration line 104, and is respectively arranged on both sides of the plurality of first portions 112 located on the first edge region 111 along the second direction Y. In practical applications, based on the position change of the first penetration line and the second penetration line in the penetration line group, among the plurality of first portions and the plurality of second portions located on the first edge region and in the same row along the first direction, it can be designed that the plurality of first portions are connected to the third penetration line, and the plurality of second portions are connected to the second penetration line.

[0063] The following Figure 2 or Figure 5 The back contact cell shown is taken as an example, and the design of the first spacing being smaller than the second spacing is explained in detail: in the process of electrically connecting a plurality of back contact cells into a photovoltaic module by means of a welding strip, the stress on the portion of the back contact cell located in the first edge area 111 is greater than the stress on the portion located in the central area 140, which is likely to affect the connection strength between the third penetration line 108 located in the first edge area 111 and the second portion 113. For example, due to excessive force on the portion of the back contact cell located in the first edge area 111, the third penetration line 108 and the second portion 113 are poorly contacted, or even the third penetration line 108 falls off from the second portion 113. Based on this, designing the first spacing to be smaller than the second spacing is conducive to making the penetration lines located in the first edge area 111 and its vicinity more densely arranged. Even if a part of the battery substrate 101 located in the first edge area 111 fails and cannot effectively collect current, the current generated in the area can be absorbed more quickly by other penetration lines with the help of the more densely arranged penetration lines, so as to ensure a good collection efficiency of the current generated in the battery substrate 101. Moreover, in addition to being in contact with the main grid and the pad on the main grid, the welding strip can also be further in contact with the third through-wire 108 and the through-wire group 45. With the help of the through-wires arranged more densely in the first edge area 111 and its vicinity, the contact area between the welding strip and the back contact cell can be increased to improve the stability of the welding strip during welding. Among them, the through-wires located in the first edge area 111 and its vicinity include the third through-wire 108 and the through-wire group 45 closest to it; the main grid includes the first main grid 102 and the second main grid 103.

[0064] In addition, Figure 5The back-contact battery shown is an example. Along the second direction Y, the edge of the third through-line 108 close to the through-line group 45 closest to it is the first edge, the edge of the first through-line 104 in the through-line group 45 closest to it close to the third through-line 108 is the second edge, and the spacing between the third through-line 108 and the through-line group 45 closest to it, that is, the first spacing, refers to: the distance between the first edge and the second edge along the second direction Y; along the second direction Y, the edge of the second through-line 105 of one group of adjacent through-line groups 45 close to the first through-line 104 of the other group is the third edge, and the edge of the first through-line 104 of the other group of adjacent through-line groups 45 close to the second through-line 105 of one group is the fourth edge, and the spacing between adjacent through-line groups 45, that is, the second spacing, refers to: the distance between the third edge and the fourth edge along the second direction Y.

[0065] and, Figure 5 In the example, N is 2, that is, the battery substrate 101 is a half-cell battery. In practical applications, the corresponding relationship between the battery substrate 101 and the whole battery cell 100 can be designed according to actual needs. For example, N can be 3, 4, 5 or 6.

[0066] In some cases, reference Figure 2 or Figure 5 , at least on part of the battery substrate 101, along the direction Y1 from the first edge area 111 to the center area 121, the spacing between different adjacent through-wire groups 45 gradually increases. It is worth noting that in the process of electrically connecting multiple back-contact batteries into a photovoltaic module by means of a welding strip, the closer to the center area 121 in the back-contact battery, the smaller the stress, and the less the contact connection between the through-wire group 45 and the first part 112 and the second part 113 is affected by external forces, so that the spacing between adjacent through-wire groups 45 can be appropriately increased on the premise that the through-wire group 45 can produce a good current balancing effect on the back-contact battery as a whole, so as to reduce the number of through-wire groups 45 to be prepared, thereby reducing the cost required for preparing the through-wire group 45. It should be noted that the second direction Y includes the direction Y1 from the first edge area 111 to the center area 121 and the direction Y2 from the center area 121 to the first edge area 111.

[0067] In some examples, continue to refer to Figure 2 or Figure 5 Among the three adjacent groups of through line groups 45 along the second direction Y, the ratio of the spacing between the two adjacent groups of through line groups 45 farther away from the first edge area 111 to the spacing between the two adjacent groups of through line groups 45 closer to the first edge area 111 is 1~2. For example, the ratio can be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8 or 1.9, etc.

[0068] The spacing between two adjacent through-line groups 45 farther from the first edge region 111 is taken as the fourth spacing, and the spacing between two adjacent through-line groups 45 closer to the first edge region 111 is taken as the fifth spacing. If the ratio of the fourth spacing to the fifth spacing is greater than 2, then for the two adjacent through-line groups 45 farther from the first edge region 111, the length of the first part 112 of the first through-line 104 of one of the two through-line groups 45 in the second direction Y is longer, and the length of the second part 113 of the second through-line 105 of the other is longer in the second direction Y. If at least a partial area of ​​the first part 112 and the second part 113 fails, the impact on the entire back contact battery is greater. Therefore, designing the ratio of the fourth spacing to the fifth spacing to be less than or equal to 2 is conducive to reducing the number of through-line groups 45 to be prepared while ensuring that the through-line groups 45 produce a good current balancing effect on the entire back contact battery.

[0069] In some cases, reference Figure 2 or Figure 5 The distance between the fourth penetration line 109 and the penetration line group 45 closest thereto is a third distance, and on at least part of the battery substrate 101, the third distance is greater than the second distance.

[0070] It should be noted that Figure 1 , Figure 2 and Figure 5 In the examples, the plurality of first portions 112 located on the second edge region 131 and in the same row along the first direction X are connected to the fourth penetration line 109, and the plurality of second portions 113 located on the second edge region 131 and in the same row along the first direction X are connected to the second penetration line 105. In other words, the fourth penetration line 109 has a different polarity from the second penetration line 105, and are respectively arranged on both sides of the plurality of first portions 112 located on the second edge region 131 along the second direction Y. In practical applications, based on the position change of the first penetration line and the second penetration line in the penetration line group, among the plurality of first portions and the plurality of second portions located on the second edge region and in the same row along the first direction, it can be designed that the plurality of second portions are connected to the fourth penetration line, and the plurality of first portions are connected to the first penetration line.

[0071] The following Figure 2 or Figure 5The back contact cell shown is an example, and the design of the third spacing being greater than the second spacing is explained in detail: in the process of electrically connecting multiple back contact cells into a photovoltaic module by means of a welding ribbon, when the cell substrate 101 is a half-cell cell, a single welding ribbon will electrically connect two cell substrates 101 at the same time, and the two cell substrates 101 are regarded as a whole cell 100, and the second edge area 131 of the two cell substrates 101 can be located in the middle of the whole cell 100. Based on this, the stress on the part of the back contact cell located in the second edge area 131 is smaller than the stress on the part located in the center area 140, and the welding stress has a smaller impact on the connection strength between the third penetration line 108 located on the first edge area 111 and the second part 113.

[0072] On the basis of the above, the third spacing is designed to be larger than the second spacing, which is conducive to making the through-wires located in the second edge area 131 and its vicinity arranged more sparsely, while ensuring that the through-wire group 45 can produce a good current-sharing effect on the entire back contact battery, so as to reduce the number of through-wire groups 45 required to be set on the entire battery cell 100, thereby reducing the preparation cost of the through-wire group 45. Among them, the through-wires located in the second edge area 131 and its vicinity include the fourth through-wire 109 and the through-wire group 45 closest to it.

[0073] In addition, Figure 5 The back-contact battery shown is an example. Along the second direction Y, the edge of the fourth through line 109 close to the through line group 45 closest to it is the fifth edge, and the edge of the second through line 105 in the through line group 45 closest to it close to the fourth through line 109 is the sixth edge. The distance between the fourth through line 109 and the through line group 45 closest to it, that is, the third distance, refers to: the distance between the fifth edge and the sixth edge along the second direction Y.

[0074] In one example, refer to Figure 5 The two battery substrates 101 can be distributed in a similar axisymmetric manner along the adjacent portions of the two battery substrates 101, and the grid lines and through lines on the two battery substrates 101 can also be distributed in a similar axisymmetric manner. The grid lines include a first main grid 102, a second main grid 103, a first fine grid 106, and a second fine grid 107, and the through lines include a first through line 104, a second through line 105, a third through line 108, and a fourth through line 109.

[0075] In some cases, reference Figure 1 or Figure 5The back-contact battery may also include: a plurality of first pads 119, each first portion 112 is in contact with at least one first pad 119; a plurality of second pads 129, each second portion 113 is in contact with at least one second pad 129; on at least part of the battery substrate 101, in the direction from the first edge area 111 to the center area 121, the number of first pads 119 located between different adjacent through-line groups 45 gradually increases, and / or the number of second pads 129 located between different adjacent through-line groups 45 gradually increases.

[0076] It is worth noting that, based on the different polarities of the first portion 112 and the second portion 113, the pads also correspond to two polarities, namely, the first pad 119 and the second pad 129. In some examples, in the direction Y1 from the first edge region 111 to the center region 121, the spacing between different adjacent through-line groups 45 gradually increases, and more first pads 119 and second pads 129 can be accommodated between adjacent through-line groups 45 with larger spacing, so as to ensure that a sufficient number of first pads 119 are arranged on the first main grid 102, and a sufficient number of second pads 129 are arranged on the second main grid 103, so as to ensure a sufficiently large contact area between the welding strip and the first main grid 102 and the second main grid 103, so as to ensure the collection effect of the welding strip on the current on the first main grid 102 and the second main grid 103.

[0077] It should be noted that Figure 1 and Figure 5 In the examples, a first portion 112 is provided with two first pads 119 and a second portion 113 is provided with two second pads 129 between a group of through-line groups 45 closest to the first edge region 111; and Figure 1 and Figure 5 In the example, three first pads 119 are provided on one first portion 112 and three second pads 129 are provided on one second portion 113 between other through-line groups 45. In practical applications, the number of first pads and second pads between adjacent through-line groups can be flexibly adjusted according to requirements.

[0078] In some embodiments, in conjunction with reference Figure 1 and Figure 6 , Figure 6 for Figure 1 The schematic diagram of a partial cross section of the back contact battery along the first cross section direction AA1 is shown. The battery substrate 101 includes a base 141 and a passivation layer 151 located on the surface of the base 141 , and the first through-line 104 and the second through-line 105 are partially embedded in the passivation layer 151 .

[0079] In this way, the first through-line 104 can not only be used to electrically connect the plurality of first portions 112 as a whole to achieve uniform current flow in the back contact battery, but also can collect the photogenerated carriers generated in the substrate 141 like a fine grid, improve the collection efficiency of the photogenerated carriers in the substrate 141, and improve the photoelectric conversion efficiency of the back contact battery. Similarly, the second through-line 105 can not only be used to electrically connect the plurality of second portions 113 as a whole to achieve uniform current flow in the back contact battery, but also can collect the photogenerated carriers generated in the substrate 141 like a fine grid, improve the collection efficiency of the photogenerated carriers in the substrate 141, and improve the photoelectric conversion efficiency of the back contact battery. The fine grid includes a first fine grid 106 and a second fine grid 107.

[0080] In some cases, the materials of both the first through-line 104 and the second through-line 105 can be the same as the material of the fine grid. For example, the slurry used to prepare the first through-line 104 and the second through-line 105 is the same as the slurry used to prepare the fine grid, and the first through-line 104 and the second through-line 105 and the fine grid are both made of a burn-through slurry, so that the first through-line 104 and the second through-line 105 also penetrate the passivation layer 151. In this way, not only the first through-line 104 can be used to electrically connect the plurality of first portions 112 as a whole, and the second through-line 105 can be used to electrically connect the plurality of second portions 113 as a whole, but also the first through-line 104 and the second through-line 105 can collect the photogenerated carriers in the substrate 141 by themselves, thereby increasing the collection path of the photogenerated carriers and improving the photoelectric conversion efficiency of the back contact cell.

[0081] In some cases, the passivation layer 151 may be a single-layer film structure or a stacked-layer film structure, and the material of the passivation layer 151 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride oxide, titanium oxide, hafnium oxide or aluminum oxide.

[0082] In some cases, the substrate 141 has a first surface and a second surface that are arranged opposite to each other, and the first surface has a suede structure. The suede structure can increase the internal reflection of the incident light to reduce optical loss and improve the photoelectric conversion efficiency of the back contact cell.

[0083] In some examples, the first surface has a front surface field (FSF), and the conductivity type of the doped ions is the same as that of the doped ions of the substrate 141. The field passivation effect is used to reduce the surface minority carrier concentration, thereby reducing the surface recombination rate, and at the same time, the series resistance can be reduced and the current transmission capacity can be improved. The first surface also has a first passivation layer and a first anti-reflection layer. The first passivation layer is located on the surface of the front surface field, and the first anti-reflection layer is located on the side of the first passivation layer away from the substrate 141. It should be noted that the substrate 141 does not necessarily include a front surface field, a first passivation layer, and a first anti-reflection layer.

[0084] In some examples, the second surface has alternately arranged first and second regions, the first region is one of the P region or the N region, the second region is the other of the P region or the N region, and there is a gap between the P region and the N region; in other examples, there may not be a gap between the P region and the N region, and there is an insulating film layer between the P region and the N region to achieve insulation between the P region and the N region, thereby achieving insulation between the first fine gate 106 and the second fine gate 107. The first fine gate 106 may be located on one of the first region and the second region, and the second fine gate 107 may be located on the other of the first region and the second region.

[0085] In some examples, the spacer region gap may be flush with the P region and the N region, that is, the substrate 141 is not etched, and the P region and the N region are insulated by some isolating film layers, and the isolating film layers may be passivation film layers or intrinsic semiconductor layers; in other examples, the spacer region gap may be lower than the P region and the spacer region gap may be lower than the N region, and the spacer region gap has a groove, which extends from the second surface toward the first surface, and the groove is used to achieve automatic isolation between regions of different conductive types, which can eliminate the leakage caused by the formation of PN junctions between heavily doped P and N regions in the back contact battery, thereby affecting the battery efficiency.

[0086] In some examples, the surface of the spacer gap may be a polished surface structure or a velvet surface structure.

[0087] In some examples, the P region and the N region may have a tunneling silicon oxide layer and a doped polysilicon layer, respectively, wherein the P region has a P-type doped polysilicon layer and the N region has an N-type doped polysilicon layer. In other examples, the P region and the N region may have an intrinsic amorphous silicon layer, a doped amorphous silicon layer and a transparent conductive layer, respectively, wherein the P region has a P-type doped amorphous silicon layer and the N region has an N-type doped amorphous silicon layer.

[0088] In some examples, a second passivation layer and a second anti-reflection layer are disposed on the P region, the N region and the gap region, and the first fine gate 106 and the second fine gate 107 are located on the second anti-reflection layer and embedded in the second passivation layer. It should be noted that the second passivation layer is the passivation layer 151 mentioned above.

[0089] In other embodiments, the materials of both the first through-line and the second through-line may be the same as the material of the first main grid. For example, the slurry used to prepare the first through-line and the second through-line is the same as the slurry used to prepare the first main grid, and the first through-line and the second through-line and the first main grid are both composed of non-burn-through slurry, and the first through-line and the second through-line are both located on the surface of the passivation layer and are not embedded in the passivation layer. In this way, it is not necessary to layout the first area and the second area of ​​the substrate surface below the first through-line and the second through-line to prevent the first through-line and the second through-line from being electrically contacted with the doping area of ​​the other polarity, resulting in a short circuit. In addition, the first through-line and the second through-line may not cause damage to the passivation layer, so that the integrity of the film layer of the passivation layer is guaranteed, thereby improving the passivation effect of the passivation layer on the substrate, which is beneficial to reducing the optical loss of the back contact battery, thereby improving the photoelectric conversion efficiency of the back contact battery. In addition, since the non-burn-through slurry does not have too much glass powder to damage the PN junction, it can effectively reduce metal composite, increase the open circuit voltage of the back contact battery, and improve the conversion efficiency of the back contact battery.

[0090] It should be noted that the conventional paste may include a mixture of metal powder, glass powder and an organic carrier. Non-burn-through paste refers to a paste that contains less glass powder than the conventional paste, has a weak burn-through ability during the sintering process, and does not need or cannot burn through the passivation layer. Burn-through paste refers to a paste that has a strong burn-through ability during the sintering process and can burn through the passivation layer.

[0091] In practical applications, the first through-line and the second through-line may also be some film layers with conductive materials or conductive wires. The first through-line only needs to electrically connect the multiple first parts into a whole, and the second through-line only needs to electrically connect the multiple second parts into a whole.

[0092] In some embodiments, reference Figure 3, along the second direction Y, the interval D1 between adjacent first portions 112 may be 10 mm to 12 mm, for example, 10.1 mm, 10.2 mm, 10.3 mm, 10.4 mm, 10.5 mm, 10.6 mm, 10.7 mm, 10.8 mm, 10.9 mm, 11 mm, 11.1 mm, 11.2 mm, 11.3 mm, 11.4 mm, 11.5 mm, 11.6 mm, 11.7 mm, 11.8 mm or 11.9 mm, etc. In this way, it is beneficial to ensure that the size of the disconnection on the first main grid 102 is moderate, and ensure that the photogenerated carriers generated in the battery substrate 101 are collected by the first main grid 102 as much as possible, so as to ensure good photoelectric conversion efficiency of the back contact battery.

[0093] In some embodiments, reference Figure 4 , along the second direction Y, the interval D2 between adjacent second portions 113 may be 10 mm to 12 mm, for example, 10.1 mm, 10.2 mm, 10.3 mm, 10.4 mm, 10.5 mm, 10.6 mm, 10.7 mm, 10.8 mm, 10.9 mm, 11 mm, 11.1 mm, 11.2 mm, 11.3 mm, 11.4 mm, 11.5 mm, 11.6 mm, 11.7 mm, 11.8 mm or 11.9 mm, etc. In this way, it is beneficial to ensure that the size of the disconnection on the second main grid 103 is moderate, and ensure that the photogenerated carriers generated in the battery substrate 101 are collected by the second main grid 103 as much as possible, so as to ensure good photoelectric conversion efficiency of the back contact battery.

[0094] In some embodiments, reference Figure 1 , Figure 2 or Figure 5 , the battery substrate 101 is divided by 1 / N whole battery cells 100, N is a positive integer greater than 1, and the whole battery cell 100 includes a first edge area 161 and a second edge area 171 opposite to each other along the first direction X; the back contact battery may also include: a first edge connection line 139 located in the first edge area 161 and extending along the second direction Y; a second edge connection line 149 located in the second edge area 171 and extending along the second direction Y; the first edge connection line 139 is in contact with and connected to one of each first penetration line 104 and each second penetration line 105, and the second edge connection line 149 is in contact with and connected to the other of each first penetration line 104 and each second penetration line 105; the width of the edge connection line in the first direction X is greater than the width of the penetration line in the second direction Y, the edge connection line includes the first edge connection line 139 and the second edge connection line 149, and the penetration line includes the first penetration line 104 and the second penetration line 105.

[0095] It is worth noting that the width of the edge connection line in the first direction X is greater than the width of the through line in the second direction Y, which means that the width of both the first edge connection line 139 and the second edge connection line 149 in the first direction X is greater than the width of the first through line 104 in the second direction Y, and greater than the width of the second through line 105 in the second direction Y.

[0096] Moreover, compared to the first through-line 104 collecting currents on the plurality of first portions 112, and the second through-line 105 collecting currents on the plurality of second portions 113, one of the first edge connection line 139 and the second edge connection line 149 collects currents on the plurality of first through-lines 104, and the other collects currents on the plurality of second through-lines 105, so that the amount of current collected on the first edge connection line 139 and the second edge connection line 149 is larger. Based on this, the width of the edge connection line in the first direction X is greater than the width of the through-line in the second direction Y, so that the cross-sectional area of ​​the first edge connection line 139 and the second edge connection line 149 is larger, and the transmission resistance thereof is smaller, which is more compatible with the amount of current required to be collected on the first edge connection line 139 and the second edge connection line 149, which is beneficial to improving the transmission efficiency of the first edge connection line 139 and the second edge connection line 149 for current, thereby further improving the photoelectric conversion efficiency of the back contact cell.

[0097] It should be noted that Figure 1 , Figure 2 or Figure 5 In the figure, the first edge connection line 139 is in contact with each second through-line 105, and the second edge connection line 149 is in contact with each first through-line 104. In actual applications, based on the change in the number of first main grids 102 and second main grids 103 arranged on the battery substrate 101, the first edge connection line can also be in contact with each first through-line, and the second edge connection line can also be in contact with each second through-line.

[0098] In some cases, the ratio of the width of the edge connection line in the first direction X to the width of the through line in the second direction Y is 2 to 30, for example, it can be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 or 29, etc.

[0099] In summary, when the overall layout area on the back contact battery remains unchanged, after the number of main grids increases, when a fault occurs in at least a local area on a first main grid 102 or a second main grid 103, the impact on the entire back contact battery will be weakened. Based on this, designing a small number of through-wire groups 45 can produce a good current balancing effect on the entire back contact battery, which is sufficient to effectively improve the electrical performance of the back contact battery and improve the anti-hot spot performance of the back contact battery. Vice versa, after the number of main grids decreases, when a fault occurs in at least a local area on a first main grid 102 or a second main grid 103, the impact on the entire back contact battery will increase, and more groups of through-wire groups 45 need to be designed to reduce the impact of the fault on the entire back contact battery, so as to ensure a good current balancing effect on the entire back contact battery and ensure good anti-hot spot performance of the back contact battery. Therefore, on the basis of designing the through line group 45, the number of through line groups 45 is designed to decrease as the number of main grids increases, which is beneficial for reducing the probability of hot spot effect in the back contact battery with the help of the through line group 45, while reducing the cost required for preparing the first main grid 102, the second main grid 103 and the through line group 45.

[0100] Another embodiment of the present disclosure further provides a photovoltaic assembly, which includes a plurality of photovoltaic cells as provided in the above embodiment, and the photovoltaic assembly is used to convert received light energy into electrical energy. It should be noted that the parts that are the same or corresponding to the above embodiment can refer to the corresponding description of the above embodiment, and will not be repeated below.

[0101] Combined with reference Figures 1 to 6 ,as well as Figure 7 and Figure 8 The photovoltaic module includes: a battery string, which is formed by connecting multiple back-contact batteries 40 provided in the above embodiments; a packaging film 41, which is used to cover the surface of the battery string; and a cover plate 42, which is used to cover the surface of the packaging film 41 away from the battery string. The back-contact batteries 40 are electrically connected in the form of a whole piece or multiple pieces to form multiple battery strings, and the multiple battery strings are electrically connected in series and / or parallel.

[0102] in, Figure 7 A partial three-dimensional schematic diagram of a photovoltaic assembly provided by another embodiment of the present disclosure, Figure 8 for Figure 7 A schematic partial cross-sectional view along the second cross-sectional direction BB1.

[0103] In some embodiments, reference Figure 7 and Figure 8 , multiple back contact cells 40 can be electrically connected via solder strips 43 . Figure 7 and Figure 8Only one positional relationship between the back contact cells is illustrated, and the grid lines of the adjacent multiple back contact cells 40 may be located on the same side, so that the welding strip 43 connects the same side of two adjacent back contact cells 40. In other embodiments, the grid lines of the adjacent multiple back contact cells may also be located on different sides, so that the welding strips respectively connect different sides of two adjacent back contact cells.

[0104] In some embodiments, the encapsulation film 41 includes a first encapsulation layer and a second encapsulation layer, wherein the first encapsulation layer covers one of the front side or the back side of the back contact battery 40, and the second encapsulation layer covers the other of the front side or the back side of the back contact battery 40. Specifically, at least one of the first encapsulation layer or the second encapsulation layer may be an organic encapsulation film such as a polyvinyl butyral (PVB) film, an ethylene-vinyl acetate copolymer (EVA) film, a polyethylene octene co-elastomer (POE) film, or a polyethylene terephthalate (PET) film, or at least one of the first encapsulation layer or the second encapsulation layer may also be an EP film, an EPE film, or a PVP film. Among them, EP film refers to a co-extruded film composed of stacked EVA film and POE film, EPE film refers to a co-extruded film formed by stacking EVA film + POE film + EVA film in sequence, and PVP film refers to a co-extruded film formed by stacking POE film + EVA film + POE film. The co-extruded film can be prepared by sequentially extruding one or more raw materials onto another already made film during the film processing process, or bonding different types of already made films together.

[0105] In some cases, there is a boundary between the first encapsulation layer and the second encapsulation layer before lamination. After the lamination process, the photovoltaic module is formed and there is no longer the concept of the first encapsulation layer and the second encapsulation layer, that is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0106] In some embodiments, the cover plate 42 may be a glass cover plate, a plastic cover plate or the like with a light-transmitting function. Specifically, the surface of the cover plate 42 facing the encapsulation film 41 may be a concave-convex surface or a velvet surface including a plurality of convex structures, thereby increasing the utilization rate of the incident light. The cover plate 42 includes a first cover plate and a second cover plate, the first cover plate is opposite to the first encapsulation layer, and the second cover plate is opposite to the second encapsulation layer.

[0107] In some cases, when the back contact cell 40 is a main grid cell, the surface of the back contact cell 40 has a plurality of main grids arranged at intervals along the first direction X and a plurality of fine grids 167 arranged at intervals along the second direction Y. Figure 1 , Figure 2 or Figure 5, the main grid includes a first main grid 102 and a second main grid 103. Figure 7 and Figure 1 The fine grid 167 includes a first fine grid 106 and a second fine grid 107. In the process of constructing a battery string using back-contact batteries 40, the welding ribbon 43 is electrically connected to at least one main grid on each back-contact battery 40 of two adjacent back-contact batteries 40.

[0108] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for implementing the present disclosure, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure, so the protection scope of the embodiments of the present disclosure shall be based on the scope defined in the claims.

Claims

1. A back contact battery, characterized in that: include: Battery substrate; A first main grid and a second main grid located on the battery substrate and arranged alternately along a first direction, wherein the first main grid comprises a plurality of first portions spaced apart along a second direction, and the second main grid comprises a plurality of second portions spaced apart along the second direction; A first penetration line extending along the first direction is in contact with and connected to a plurality of first portions in the same row along the first direction; A second penetration line extending along the first direction is in contact with and connected to a plurality of second portions in the same row along the first direction; The adjacent first through-lines and the second through-lines are formed as a through-line group, the number of the through-line groups decreases as the number of main grids increases, and along the second direction, the width of at least one of the first through-lines and the second through-lines decreases as the number of main grids increases, and the number of main grids is the sum of the number of the first main grids and the number of the second main grids.

2. The back contact cell according to claim 1, characterized in that: The number of main grids is less than a first threshold, and the number of through-line groups is greater than a first preset value; or, the number of main grids is greater than or equal to a first threshold, and the number of through-line groups is less than a second preset value; wherein the first preset value is greater than the second preset value.

3. The back contact cell according to claim 1 or 2, characterized in that: Also includes: A first fine grid and a second fine grid are located on the battery substrate and are alternately arranged along the second direction, the second fine grid is disconnected at the first main grid, the first fine grid is disconnected at the second main grid, the disconnected portion of the second fine grid is used for the first main grid to be in contact with and connected to a plurality of the first fine grids along the second direction, and the disconnected portion of the first fine grid is used for the second main grid to be in contact with and connected to a plurality of the second fine grids along the second direction; The number of main gates is less than a first threshold value, and along the second direction, the ratio of the width of at least one of the first through-line and the second through-line to the width of the fine gate is within a first preset range; or, the number of main gates is greater than or equal to the first threshold value, and along the second direction, the ratio of the width of at least one of the first through-line and the second through-line to the width of the fine gate is within a second preset range; wherein the minimum value of the first preset range is greater than the minimum value of the second preset range, the maximum value of the first preset range is greater than the maximum value of the second preset range, and the fine gate includes the first fine gate and the second fine gate.

4. The back contact cell according to claim 1, characterized in that: The battery substrate is divided into 1 / N whole battery sheets, N is a positive integer greater than 1; the battery substrate includes a first edge area, a center area and a second edge area arranged in sequence along the second direction, and at least part of the first edge area of ​​the battery substrate is located at the edge of the whole battery sheet: The back contact battery further comprises: a third penetration line located on the first edge region and extending along the first direction; a fourth penetration line located on the second edge region and extending along the first direction; Among them, one of the plurality of first portions and the plurality of second portions located on the first edge region and in the same row along the first direction is in contact with the third penetration line, and the other is in contact with the first penetration line or the second penetration line; one of the plurality of first portions and the plurality of second portions located on the second edge region and in the same row along the first direction is in contact with the fourth penetration line, and the other is in contact with the first penetration line or the second penetration line; Along the second direction, the distance between the third penetration line and the penetration line group closest thereto is a first distance, the distance between adjacent penetration line groups is a second distance, and the first distance is smaller than the second distance.

5. The back contact cell according to claim 4, characterized in that: On at least a portion of the battery substrate, in a direction from the first edge region to the central region, the spacing between different adjacent through line groups gradually increases.

6. The back contact cell according to claim 5, characterized in that: Among the three adjacent through line groups along the second direction, the ratio of the spacing between two adjacent through line groups farther from the first edge area to the spacing between two adjacent through line groups closer to the first edge area is 1-2.

7. The back contact cell according to claim 4, characterized in that: The distance between the fourth penetration line and the penetration line group closest thereto is a third distance, and on at least part of the battery substrate, the third distance is greater than the second distance.

8. The back contact battery according to claim 4, characterized in that Also includes: A plurality of first pads, each of the first portions being in contact with and connected to at least one of the first pads; A plurality of second pads, each of the second portions being in contact with and connected to at least one of the second pads; On at least part of the battery substrate, in the direction from the first edge area to the center area, the number of the first welding pads located between different adjacent through-line groups gradually increases, and / or the number of the second welding pads located between different adjacent through-line groups gradually increases.

9. The back contact cell according to claim 1, characterized in that: The battery substrate includes a substrate and a passivation layer located on a surface of the substrate, and the first through-line and the second through-line are partially embedded in the passivation layer.

10. A photovoltaic module, characterized in that: include: A battery string, wherein the battery string is formed by connecting a plurality of back-contact batteries according to any one of claims 1 to 9; A packaging film, wherein the packaging film covers the battery string; A cover plate is located on a side of the packaging film away from the battery string.

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