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, and the number of the main grids is the sum of the number of the first and second main grids, thereby at least facilitating the improvement of the electrical performance of the back contact battery and the reduction of the preparation cost of the back contact battery.

Description

[0001] Cross - Reference to Related Applications

[0002] This application is a divisional application of a Chinese invention patent application with an application date of March 10, 2025, an application number of 202510279667.8, and an invention title of "Back Contact Battery and Photovoltaic Module". Technical Field

[0003] The present disclosure relates to the field of photovoltaics, and particularly to a back contact battery and a photovoltaic module. Background Art

[0004] An interdigitated back contact (IBC) battery is a back-junction back-contact photovoltaic battery, and its positive and negative electrodes are arranged in an interdigitated manner on the backlight side of the photovoltaic battery. There is no metal electrode blocking on the light-receiving surface of the battery, thereby effectively increasing the short-circuit current of the photovoltaic battery. Multiple photovoltaic batteries are electrically connected through solder tapes to form a photovoltaic module. The current generated in the photovoltaic battery is first collected by the fine grid, then collected by the main grid electrically connected to the fine grid, and then collected by the solder tape electrically connected to the main grid.

[0005] However, different main grids are electrically connected to different solder tapes respectively, and different solder tapes are also spaced from each other. The collection path of the current generated in the IBC battery by the solder tape is relatively single, and the current can only be collected from different main grids respectively. If the fine grid and / or the main grid in a local area of the IBC battery fails and cannot effectively collect the current, it is easy to cause a large difference in the current magnitude between this local area and other areas of the IBC battery, and it is easy to occur hot spot effect at the position where the local failure occurs, reducing the photoelectric conversion efficiency of the IBC battery.

[0006] Therefore, the electrical performance of the back contact battery needs to be further improved. Summary of the Invention

[0007] Embodiments of the present disclosure provide a back contact battery and a photovoltaic module, which are at least beneficial to improving the electrical performance of the back contact battery and reducing the manufacturing cost of the back contact battery.

[0008] According to some embodiments of the present disclosure, on the one hand, an embodiment of the present disclosure provides a back-contact battery, including: a battery substrate; a first main grid and a second main grid located on the battery substrate and arranged alternately in a first direction, the first main grid including a plurality of first parts spaced apart in a second direction, and the second main grid including a plurality of second parts spaced apart in the second direction; a first through-line extending in the first direction and in contact connection with a plurality of the first parts in the same row in the first direction; a second through-line extending in the first direction and in contact connection with a plurality of the second parts in the same row in the first direction; adjacent ones of the first through-line and the second through-line form a set of through-lines, and the number of sets of the 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.

[0009] In some embodiments, the number of main grids is less than a first threshold, and the number of sets of the through-lines is greater than a first preset value; or, the number of main grids is greater than or equal to the first threshold, and the number of sets of the through-lines is less than a second preset value; wherein, the first preset value is greater than the second preset value.

[0010] In some embodiments, the number of main grids is greater than or equal to 18, and the number of sets of the through-lines is less than 4.

[0011] In some embodiments, in the second direction, the width of at least one of the first through-line and the second through-line decreases as the number of main grids increases.

[0012] In some embodiments, the back-contact battery further includes: a first fine grid and a second fine grid located on the battery substrate and arranged alternately in 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 disconnection point of the second fine grid is for the first main grid to be in contact connection with a plurality of the first fine grids in the second direction, and the disconnection point of the first fine grid is for the second main grid to be in contact connection with a plurality of the second fine grids in the second direction; the number of main grids is less than a first threshold, and in 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 grid is within a first preset range; or, the number of main grids is greater than or equal to the first threshold, and in 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 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 grid includes the first fine grid and the second fine grid.

[0013] In some embodiments, the battery substrate is separated by 1 / N whole battery cells, where N is a positive integer greater than 1; the battery substrate includes a first edge region, a central region, and a second edge region arranged in sequence along the second direction, and at least a part of the first edge region of the battery substrate is located at the edge of the whole battery cell: the back-contact battery further includes: a third through-line located on the first edge region and extending along the first direction; a fourth through-line located on the second edge region and extending along the first direction; wherein, among a plurality of the first parts and a plurality of the second parts that are in the same row along the first direction on the first edge region, one is in contact connection with the third through-line, and the other is in contact connection with the first through-line or the second through-line; among a plurality of the first parts and a plurality of the second parts that are in the same row along the first direction on the second edge region, one is in contact connection with the fourth through-line, and the other is in contact connection with the first through-line or the second through-line; along the second direction, the distance between the third through-line and the nearest through-line group thereto is a first distance, and the distance between adjacent through-line groups is a second distance, and the first distance is less than the second distance.

[0014] In some embodiments, on at least a part of the battery substrate, along the direction from the first edge region to the central region, the distance between different adjacent through-line groups gradually increases.

[0015] In some embodiments, among three adjacent through-line groups along the second direction, the ratio of the distance between the two adjacent through-line groups farther from the first edge region to the distance between the two adjacent through-line groups closer to the first edge region is 1 to 2.

[0016] In some embodiments, the distance between the fourth through-line and the nearest through-line group thereto is a third distance, and on at least a part of the battery substrate, the third distance is greater than the second distance.

[0017] In some embodiments, the back-contact battery further includes: a plurality of first pads, each of the first parts is in contact connection with at least one of the first pads; a plurality of second pads, each of the second parts is in contact connection with at least one of the second pads; on at least a part of the battery substrate, along the direction from the first edge region to the central region, the number of the first pads located between different adjacent through-line groups gradually increases, and / or the number of the second pads located between different adjacent through-line groups gradually increases.

[0018] In some embodiments, the battery substrate includes a substrate and a passivation layer located on the surface of the substrate, and both the first through-line and the second through-line are partially embedded in the passivation layer.

[0019] In some embodiments, along the second direction, the interval between adjacent first parts is 10 mm to 12 mm; and / or, along the second direction, the interval between adjacent second parts is 10 mm to 12 mm.

[0020] According to some embodiments of the present disclosure, on the other hand, an embodiment of the present disclosure further provides a photovoltaic module, including: a battery string formed by connecting a plurality of back contact batteries as described in any one of the above; an encapsulation film covering the battery string; and a cover plate located on a side of the encapsulation film away from the battery string.

[0021] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages:

[0022] When the overall layout area on the back contact battery remains unchanged, after the number of main grids increases, when at least a partial area on a certain first main grid or second main grid fails, 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 the anti-thermal spot performance of the back contact battery. Vice versa, after the number of main grids decreases, when at least a partial area on a certain first main grid or second main grid fails, 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 failure on the entire back contact battery to ensure a good current sharing effect on the entire back contact battery and ensure good anti-thermal spot performance of the back contact battery. Therefore, on the basis of designing the through-wire groups, the number of groups of through-wire groups is designed to decrease as the number of main grids increases, which is beneficial to reducing the probability of the back contact battery having a thermal spot effect and improving the electrical performance while reducing the costs required for preparing the first main grid, the second main grid, and the through-wire groups. Description of the Drawings

[0023] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the figures in the drawings do not constitute a proportional limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the following-described drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a first partial top view schematic diagram of a back contact battery provided by an embodiment of the present disclosure;

[0025] Figure 2The second partial top view schematic diagram of the back-contact battery provided by an embodiment of the present disclosure;

[0026] Figure 3 A partial top view schematic diagram of a single first main grid in the back-contact battery provided by an embodiment of the present disclosure;

[0027] Figure 4 A partial top view schematic diagram of a single second main grid in the back-contact battery provided by an embodiment of the present disclosure;

[0028] Figure 5 The third partial top view schematic diagram of the back-contact battery provided by an embodiment of the present disclosure;

[0029] Figure 6 is Figure 1 A partial cross-sectional schematic diagram of the back-contact battery shown along the first cross-section direction AA1;

[0030] Figure 7 A partial three-dimensional schematic diagram of a photovoltaic module provided by another embodiment of the present disclosure;

[0031] Figure 8 is Figure 7 A partial cross-sectional schematic diagram along the second cross-section direction BB1. Detailed implementation manners

[0032] As can be seen from the background art, the electrical performance of the back-contact battery needs to be improved.

[0033] Through analysis, it is found that in an IBC battery, for different like-polarity main grids, for example, the current on different positive main grids is collected by different solder tapes, and there is no path for the current collected on different like-polarity main grids and their corresponding solder tapes to flow through each other. If a local area of the IBC battery, such as a local area of a certain main grid, fails and cannot effectively collect current, the actual current collected on this main grid is smaller than the ideal state, resulting in a large difference between the actual current on this main grid and the actual current on other like-polarity main grids. This will reduce the uniformity of current transmission on the entire cell, causing the faulty area on the cell to heat up, generating more heat, resulting in the hot spot effect, and further reducing the photoelectric conversion efficiency of the IBC battery and the uniformity of the overall photoelectric conversion efficiency of the IBC battery.

[0034] The present disclosure provides a back-contact battery and a photovoltaic module. In the back-contact battery, when the overall layout area on the back-contact battery remains unchanged and the number of main grids increases, when at least a partial area on a certain first main grid or second main grid fails, the impact on the entire back-contact battery will be weakened. Based on this, designing a small number of through-wire groups can achieve 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 enhance the anti-hot-spot performance of the back-contact battery. Vice versa, when the number of main grids decreases, when at least a partial area on a certain first main grid or second main grid fails, the impact on the entire back-contact battery will increase. More groups of through-wire groups need to be designed to reduce the impact of the failure on the entire back-contact battery to ensure a good current-sharing effect on the entire back-contact battery and ensure the good anti-hot-spot performance of the back-contact battery. Therefore, on the basis of designing the through-wire groups, designing the number of groups of through-wire groups to decrease as the number of main grids increases is beneficial to reducing the probability of the back-contact battery having a hot-spot effect and improving the electrical performance while reducing the costs required for preparing the first main grid, the second main grid, and the through-wire groups.

[0035] 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 indicating 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 of" is more than two, unless otherwise specifically and clearly defined.

[0036] Referring to "embodiments" in this article 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 appearance of this phrase 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. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0037] 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: the existence of A, the simultaneous existence of A and B, and the existence of B. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0038] In the description of the embodiments of the present disclosure, the term "a plurality of" refers to more than two (including two). Similarly, "a plurality of groups" refers to more than two groups (including two groups), and "a plurality of pieces" refers to more than two pieces (including two pieces).

[0039] In the description of the embodiments of the present disclosure, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the embodiments of the present disclosure.

[0040] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "install", "connect", "couple", "fix", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific situations.

[0041] In the corresponding drawings of the embodiments of the present disclosure, for better understanding and convenience of description, the thickness and area of the layer are enlarged. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.

[0042] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise stated, other components are not excluded, and other components may further be included. In addition, when a component such as a layer, film, region, or plate is referred to as "on / located on" another component, it can be "directly on" the other component (that is, on the surface of the other component and there is no other component between the two), or there can be another component therebetween. In addition, when a layer, film, region, plate, etc. is "directly located on" another component, or when a layer, film, region, plate, etc. is located on the surface of another component, it means that there is no other component therebetween.

[0043] The terms used in the description of the various embodiments herein are for the purpose of describing particular embodiments only and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is also intended to include the plural form unless the context clearly indicates otherwise. Among them, the component includes components such as layers, films, regions, or plates.

[0044] The embodiments of the present disclosure will be described in detail below in conjunction with 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 to help readers better understand the embodiments of the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the embodiments of the present disclosure can still be implemented.

[0045] An embodiment of the present disclosure provides a back-contact battery, and the back-contact battery provided by an embodiment of the present disclosure will be described in detail below in conjunction with the accompanying drawings.

[0046] With reference to Figures 1 to 4 , the back-contact battery includes: a battery substrate 101; a first main grid 102 and a second main grid 103 arranged alternately on the battery substrate 101 along the first direction X, the first main grid 102 includes a plurality of first parts 112 arranged at intervals along the second direction Y, and the second main grid 103 includes a plurality of second parts 113 arranged at intervals along the second direction Y; a first through-line 104 extending along the first direction X, which is in contact connection with a plurality of first parts 112 in the same row along the first direction X; a second through-line 105 extending along the first direction X, which is in contact connection with a plurality of second parts 113 in the same row along the first direction X.

[0047] Further, with reference to Figure 1 and Figure 2 , adjacent first through-line 104 and second through-line 105 form a set of through-line groups 45, the number of sets of through-line groups 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 the first main grids 102 and the number of the second main grids 103.

[0048] Among them, Figure 1 is the first partial top view schematic diagram of the back-contact battery provided by an embodiment of the present disclosure; Figure 2 is the second partial top view schematic diagram of the back-contact battery provided by an embodiment of the present disclosure; Figure 3 is a partial top view schematic diagram of a single first main grid in the back-contact battery provided by an embodiment of the present disclosure; Figure 4A partial top view schematic diagram of a single second main grid in the back-contact battery provided by an embodiment of the present disclosure. It should be noted that, for the convenience of distinguishing the first main grid 102 and the second main grid 103, Figure 1 and Figure 2 different filling methods are used to draw the first main grid 102 and the second main grid 103 in both.

[0049] It is worth emphasizing that, comparing with the 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 evenly distributed to each first main grid 102 and the current evenly distributed to each second main grid 103 will both decrease. When at least a partial area on a certain first main grid 102 or a certain second main grid 103 fails, 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 improve the anti-thermal-spot performance of the back-contact battery. Vice versa, after the number of main grids decreases, the current evenly distributed to each first main grid 102 and the current evenly distributed to each second main grid 103 will both increase. When at least a partial area on a certain first main grid 102 or a certain second main grid 103 fails, the impact on the entire back-contact battery will increase. More groups of through-wire groups 45 need to be designed to reduce the impact of the failure on the entire back-contact battery to ensure a good current-sharing effect on the entire back-contact battery and ensure the good anti-thermal-spot performance of the back-contact battery. Moreover, whether the number of main grids increases or the number of groups of the through-wire groups 45 increases, the manufacturing cost of the back-contact battery will increase.

[0050] Therefore, on the basis of designing the through-wire groups 45, designing the number of groups of the through-wire groups 45 to decrease as the number of main grids increases is beneficial to reducing the probability of the back-contact battery having a thermal-spot effect and improving the electrical performance with the help of the through-wire groups 45, while reducing the costs required for manufacturing the first main grid 102, the second main grid 103, and the through-wire groups 45, so as to balance the improvement of the electrical performance of the back-contact battery and the reduction of the manufacturing cost.

[0051] The following will detail how the through-wire groups 45 can produce a good current-sharing effect on the entire back-contact battery to improve the electrical performance of the back-contact battery.

[0052] It should be noted that the first through-line 104 can electrically connect multiple first parts 112 in the same row along the first direction X at the same time, so that the multiple first parts 112 are electrically connected to each other. Then, the current on the multiple first parts 112 can have multiple flow paths based on the first through-line 104. Moreover, multiple first parts 112 in the same row along the first direction X belong to different first main grids 102 respectively. In other words, different first parts 112 among the multiple first parts 112 in the same row along the first direction X correspond to sub-components of different first main grids 102. Thus, by using the first through-line 104 to electrically connect multiple first parts 112 in the same row along the first direction X, it is possible to interconnect multiple first main grids 102 arranged at intervals along the first direction X, forming a denser current transmission path, and by means of the first through-line 104, each first part 112 in the same row along the first direction X is at the same potential, that is, effectively avoiding the existence of potential difference between each first part 112 in the same row along the first direction X.

[0053] In addition, in the same first main grid 102, at least some different first parts 112 are respectively in contact connection with different first through-lines 104. When connecting multiple back-contact batteries with solder tapes later, different first through-lines 104 will be electrically connected to the same solder tape, so that different first through-lines 104 are also interconnected with each other, further forming a denser current transmission path, and by means of the solder tape, different first through-lines 104 are also at the same potential, that is, effectively avoiding the existence of potential difference between different first through-lines 104. Thus, even if the first main grid 102 is disconnected into multiple first parts 112, multiple first main grids 102 can be electrically connected into a whole by means of multiple first through-lines 104, so that multiple first main grids 102 are at the same potential. Based on this, even if a part of the first main grid 102 fails, through the connection of the first through-line 104, the current on multiple first main grids 102 can be equalized again, so that multiple first main grids 102 are at the same potential again, thus effectively avoiding the phenomenon of local area failure heating.

[0054] Similarly, the second through-wire 105 can electrically connect multiple second parts 113 in the same row along the first direction X at the same time, so that the multiple second parts 113 are electrically connected to each other. Then, the current on the multiple second parts 113 can have multiple flow paths based on the second through-wire 105. Moreover, the multiple second parts 113 in the same row along the first direction X belong to different second main grids 103 respectively. In other words, different second parts 113 among the multiple second parts 113 in the same row along the first direction X all correspond to sub-components of different second main grids 103. Thus, by using the second through-wire 105 to electrically connect the multiple second parts 113 in the same row along the first direction X at the same time, it is possible to interconnect the multiple second main grids 103 arranged at intervals along the first direction X, forming a denser current transmission path, and making each of the second parts 113 in the same row along the first direction X at the same potential through the second through-wire 105, that is, effectively avoiding the potential difference between each of the second parts 113 in the same row along the first direction X.

[0055] In addition, in the same second main grid 103, at least some different second parts 113 are respectively in contact connection with different second through-wires 105. When multiple back-contact batteries are connected by solder tapes later, different second through-wires 105 will be electrically connected to the same solder tape, so that different second through-wires 105 are also interconnected with each other, further forming a denser current transmission path, and making different second through-wires 105 at the same potential through the solder tape, that is, effectively avoiding the potential difference between different second through-wires 105. Thus, even if the second main grid 103 is disconnected into multiple second parts 113, the multiple second main grids 103 can be electrically connected into a whole by means of multiple second through-wires 105, so that the multiple second main grids 103 are at the same potential. Based on this, even if a part of the second main grid 103 fails, through the connection of the second through-wires 105, the current on the multiple second main grids 103 can be equalized again to make the multiple second main grids 103 at the same potential again, thus effectively avoiding the phenomenon of local area failure heating.

[0056] Therefore, designing the via line group 45 including the adjacent first via line 104 and second via line 105 is beneficial to interconnecting multiple first main grids 102 into a whole, and is also beneficial to interconnecting multiple second main grids 103 into a whole, and ensuring insulation between the first main grid 102 and the second main grid 103. In this way, even if a local area of the back contact battery fails and cannot effectively collect current, resulting in the actually collected current on the failed local area being smaller than the ideal state, based on the function of the via line group 45, uniform current flow can be realized again on multiple first main grids 102 and multiple second main grids 103 respectively, so as to improve the overall electrical performance of the back contact battery, such as current density homogenization, thereby improving the uniformity of the overall photoelectric conversion efficiency of the back contact battery, and avoiding local heating problems caused by excessive current differences in different areas of the back contact battery sheet, so as to enhance the thermal spot resistance performance of the back contact battery.

[0057] It should be noted that the failure of the local area of the back contact battery includes but is not limited to the following situations: In some cases, at least partial failure occurs in at least one first main grid 102 or at least one second main grid 103, such as dimensional changes or broken grids caused by printing accuracy; In other cases, there are certain defects in the material forming the substrate in the back contact battery, such as differences in surface defects in different areas of the substrate; In still other cases, there are large differences in the light intensity received by different areas of the back contact battery, such as partial occlusion of the back contact battery.

[0058] It is worth noting that referring to Figure 3 , designing the first main grid 102 to include multiple first parts 112 arranged at intervals in the second direction Y can be regarded as, in the second direction Y, disconnecting the first main grid 102 into multiple segments, and each segment serves as a first part 112; Referring to Figure 4 , designing the second main grid 103 to include multiple second parts 113 arranged at intervals in the second direction Y can be regarded as, in the second direction Y, disconnecting the second main grid 103 into multiple segments, and each segment serves as a second part 113. Among them, in combination with referring to Figures 1 to 4 , at the disconnection of the first main grid 102, that is, the interval between adjacent first parts 112 in the second direction Y is used for the second via line 105 to pass through; at the disconnection of the second main grid 103, that is, the interval between adjacent second parts 113 in the second direction Y is used for the first via line 104 to pass through.

[0059] The following details a back contact battery provided by an embodiment of the present disclosure.

[0060] In some embodiments, in combination with referring to Figures 1 to 4, the number of main grids is less than the first threshold, and the number of groups of the through-line group 45 is greater than the first preset value; or, the number of main grids is greater than or equal to the first threshold, and the number of groups of the through-line group 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 main grids and the number of groups of the through-line group 45 on the back-contact battery, a first threshold is set for the number of main grids. Compared with the case where the number of main grids is greater than or equal to the first threshold, when the number of main grids is less than the first threshold, the number of groups of the through-line group 45 is more. By means of the through-line group 45 with a larger number of groups, the influence on the current uniformity on the back-contact battery chip when some main grids fail is reduced, so as to ensure that the back-contact battery has good electrical performance.

[0061] It should be noted that some main grids failing includes but is not limited to the following situations: the main grid has a fracture phenomenon, that is, a broken grid; or, there are relatively large surface defects on the substrate opposite to the main grid; or, the area where the main grid is located is blocked, and the illumination intensity received is significantly reduced. Among them, the main grid includes the first main grid 102 or the second main grid 103. In addition, Figure 1 and Figure 2 are both partial top views of the back-contact battery. For the clarity of the illustration, Figure 1 and Figure 2 although show the left and right sides of the battery substrate 101 along the first direction X, they do not show all the first main grids 102 and all the second main grids 103 on the battery substrate 101.

[0062] In some examples, the first threshold can be 18, 19, 20 or 21, etc., the first preset value can be 4, 5 or 6, etc., and the second preset value can be 2, 3 or 4, etc.

[0063] In one example, the first threshold can be 20, the first preset value can be 5, etc., and the second preset value can be 3. In other words, when the number of main grids is less than 20, 5 groups of through-line groups 45 are designed; when the number of main grids is greater than or equal to 20, 3 groups of through-line groups 45 are designed.

[0064] In some embodiments, with reference to Figures 1 to 4 , the back-contact battery may further include: a first fine grid 106 and a second fine grid 107 that are alternately arranged on the battery substrate 101 along the second direction Y. The second fine grid 107 is disconnected at the first main grid 102, the first fine grid 106 is disconnected at the second main grid 103, and the disconnection point of the second fine grid 107 is used for the first main grid 102 to contact and connect with a plurality of first fine grids 106 along the second direction Y, and the disconnection point of the first fine grid 106 is used for the second main grid 103 to contact and connect with a plurality of second fine grids 107 along the second direction Y.

[0065] On this basis, the correlation design of the number of main grids and the widths of the first through-line 104, the second through-line 105, and the fine grids in the second direction Y can be at least divided into the following two cases: In some cases, the number of main grids is less than the first threshold, 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 grids is within the first preset range; In other cases, the number of main grids is greater than or equal to the first threshold, 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 grids is within the second preset range.

[0066] Among them, 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 106 and the second fine grid 107.

[0067] It should be noted that for the convenience of distinguishing the first fine grid 106 and the second fine grid 107, Figure 1 and Figure 2 both use solid lines to indicate the first fine grid 106 and dotted lines to indicate the second fine grid 107.

[0068] It is worth noting that when the number of main grids is less than the first threshold, 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 grids is taken as the first ratio; when the number of main grids is greater than or equal to the first threshold, 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 grids 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] In some embodiments, referring to Figure 1 , Figure 2 or Figure 5 , Figure 5 is the third partial top view schematic diagram of the back contact battery provided by an embodiment of the present disclosure. The battery substrate 101 can be separated by 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 central region 121, and a second edge region 131 arranged in sequence along the second direction Y, and at least a part of the first edge region 111 of the battery substrate 101 is located at the edge of the whole battery cell 100.

[0073] It should be noted that Figure 1 and Figure 2 can be regarded as examples where a single back contact battery includes 1 battery substrate 101, Figure 5 can be regarded as an example where a single back contact battery includes 2 battery substrates 101. In addition, for the convenience of distinguishing 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; moreover, Figure 1 , Figure 2 and Figure 5 all show the first fine grid 106 with a thinner solid line and the second fine grid 107 with a thinner dashed line; Figure 1 , Figure 2 and Figure 5 all show the first through line 104 with a thicker solid line and the second through line 105 with a thicker dashed line.

[0074] Based on this, continuing to refer to Figure 1 , Figure 2 or Figure 5 , the back contact battery may further include: a third through line 108 located on the first edge region 111 and extending along the first direction X; a fourth through line 109 located on the second edge region 131 and extending along the first direction X; wherein, one of a plurality of first parts 112 and a plurality of second parts 113 located on the first edge region 111 and in the same row along the first direction X is in contact connection with the third through line 108, and the other is in contact connection with the first through line 104 or the second through line 105; one of a plurality of first parts 112 and a plurality of second parts 113 located on the second edge region 131 and in the same row along the first direction X is in contact connection with the fourth through line 109, and the other is in contact connection with the first through line 104 or the second through line 105; along the second direction Y, the distance between the third through line 108 and the nearest through line group 45 is a first distance, and the distance between adjacent through line groups 45 is a second distance, and the first distance is less than the second distance.

[0075] It should be noted that Figure 1 , Figure 2And Figure 5 In both cases, it is exemplified that a plurality of second portions 113 located on the first edge region 111 and in the same row along the first direction X are in contact connection with the third through-line 108, and a plurality of first portions 112 located on the first edge region 111 and in the same row along the first direction X are in contact connection with the first through-line 104. In other words, the polarities of the third through-line 108 and the first through-line 104 are different, and they are respectively arranged on both sides of a plurality of first portions 112 located on the first edge region 111 along the second direction Y. In practical applications, based on the position changes of the first through-line and the second through-line in the through-line group, among a plurality of first portions and a plurality of second portions located on the first edge region and in the same row along the first direction, a plurality of first portions can be designed to be in contact connection with the third through-line, and a plurality of second portions can be in contact connection with the second through-line.

[0076] The following takes Figure 2 Or Figure 5 The back-contact battery shown as an example to elaborate on the design that the first pitch is smaller than the second pitch: During the process of electrically connecting a plurality of back-contact batteries into a photovoltaic module by means of a solder ribbon, the stress on the part of the back-contact battery located in the first edge region 111 is greater than that on the part located in the central region 140, which is likely to affect the connection strength between the third through-line 108 and the second portion 113 located on the first edge region 111. For example, due to excessive force on the part of the back-contact battery located in the first edge region 111, the contact between the third through-line 108 and the second portion 113 is poor or even the third through-line 108 falls off from the second portion 113, etc. Based on this, designing the first pitch to be smaller than the second pitch is beneficial to making the arrangement of the through-lines in the first edge region 111 and its vicinity denser. Even if a part of the battery substrate 101 in the first edge region 111 fails to effectively collect current, the current generated in this region can be absorbed by other through-lines more quickly with the help of the denser arranged through-lines, so as to ensure good collection efficiency of the current generated in the battery substrate 101. Moreover, in addition to being in contact connection with the main grid and the pads on the main grid, the solder ribbon can further be in contact connection with the third through-line 108 and the through-line group 45. With the help of the denser arranged through-lines in the first edge region 111 and its vicinity, the contact area between the solder ribbon and the back-contact battery sheet can be increased to improve the stability during the soldering of the solder ribbon. Among them, the through-lines in the first edge region 111 and its vicinity include the third through-line 108 and the through-line group 45 closest to it; the main grid includes the first main grid 102 and the second main grid 103.

[0077] In addition, taking Figure 5The back-contact battery shown is an example. Along the second direction Y, the edge of the third through-wire 108 closest to the through-wire group 45 nearest to it is the first edge, and the edge of the first through-wire 104 in the through-wire group 45 nearest to it and closest to the third through-wire 108 is the second edge. The spacing between the third through-wire 108 and the through-wire group 45 nearest 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-wire 105 in one of the adjacent through-wire groups 45 closest to the first through-wire 104 in the other group is the third edge, and the edge of the first through-wire 104 in the other adjacent through-wire group 45 closest to the second through-wire 105 in one group is the fourth edge. The spacing between the adjacent through-wire groups 45, that is, the second spacing, refers to the distance between the third edge and the fourth edge along the second direction Y.

[0078] Moreover, Figure 5 only N = 2 is taken as an example, that is, the battery substrate 101 is a half-cell. 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, etc.

[0079] In some cases, referring to Figure 2 or Figure 5 , along the direction Y1 from the first edge region 111 to the central region 121 on at least part of the battery substrate 101, the spacing between different adjacent through-wire groups 45 gradually increases. It should be noted that during the process of electrically connecting multiple back-contact batteries into a photovoltaic module by means of solder tapes, the stress on the back-contact battery closer to the central region 121 is smaller, and the contact connection between the through-wire group 45 and the first part 112 and the second part 113 is less affected by external forces. Then, on the premise of ensuring that the through-wire group 45 can produce a good current-sharing effect on the whole back-contact battery, the spacing between adjacent through-wire groups 45 can be appropriately increased to reduce the number of through-wire groups 45 to be prepared, thereby reducing the cost required to prepare the through-wire group 45. It should be noted that the second direction Y includes the direction Y1 from the first edge region 111 to the central region 121 and the direction Y2 from the central region 121 to the first edge region 111.

[0080] In some examples, continuing to refer to Figure 2 or Figure 5 , among three adjacent through-wire groups 45 along the second direction Y, the ratio of the spacing between the two adjacent through-wire groups 45 farther from the first edge region 111 to the spacing between the two adjacent through-wire groups 45 closer to the first edge region 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.

[0081] The distance between two adjacent groups of through-wire groups 45 that are farther from the first edge region 111 is taken as the fourth distance, and the distance between two adjacent groups of through-wire groups 45 that are closer to the first edge region 111 is taken as the fifth distance. If the ratio of the fourth distance to the fifth distance is greater than 2, then for two adjacent groups of through-wire groups 45 that are farther from the first edge region 111, the length of the first part 112 in the second direction Y that the first through-wire 104 of one of the two through-wire groups 45 contacts and connects is longer, and the length of the second part 113 in the second direction Y that the second through-wire 105 of the other through-wire group 45 contacts and connects is longer. If at least a partial region on 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 distance to the fifth distance to be less than or equal to 2 is beneficial to ensuring a good current-sharing effect on the entire back-contact battery while reducing the number of through-wire groups 45 to be prepared.

[0082] In some cases, referring to Figure 2 or Figure 5 , the distance between the fourth through-wire 109 and the through-wire group 45 closest to it is the third distance. On at least part of the battery substrate 101, the third distance is greater than the second distance.

[0083] It should be noted that Figure 1 , Figure 2 and Figure 5 both take as an example that a plurality of first parts 112 located on the second edge region 131 and in the same row along the first direction X are in contact connection with the fourth through-wire 109, and a plurality of second parts 113 located on the second edge region 131 and in the same row along the first direction X are in contact connection with the second through-wire 105. In other words, the fourth through-wire 109 and the second through-wire 105 have different polarities and are respectively arranged on both sides of a plurality of first parts 112 located on the second edge region 131 in the second direction Y. In practical applications, based on the position changes of the first through-wire and the second through-wire in the through-wire group, among a plurality of first parts and a plurality of second parts located on the second edge region and in the same row along the first direction, it is possible to design that a plurality of second parts are in contact connection with the fourth through-wire, and a plurality of first parts are in contact connection with the first through-wire.

[0084] The following takes Figure 2 or Figure 5Taking the back-contact cell shown as an example, the design of the third pitch being greater than the second pitch will be described in detail: In the process of electrically connecting multiple back-contact cells into a photovoltaic module by means of welding tapes, when the cell substrate 101 is a half cell, a single welding tape will electrically connect 2 cell substrates 101 at the same time. Regarding the 2 cell substrates 101 as a whole cell piece 100, the second edge regions 131 of the 2 cell substrates 101 can be located in the middle of the whole cell piece 100. Based on this, the stress on the part of the back-contact cell located in the second edge region 131 is smaller than the stress on the part located in the central region 140. Then, the influence of the welding stress on the connection strength between the third through-line 108 and the second part 113 on the first edge region 111 is smaller.

[0085] On the above basis, designing the third pitch to be greater than the second pitch is beneficial to making the arrangement of the through-lines in the second edge region 131 and its vicinity sparser on the premise of ensuring that the through-line group 45 can produce a good current-sharing effect on the whole back-contact cell, so as to reduce the number of through-line groups 45 required to be arranged on the whole cell piece 100, and reduce the manufacturing cost of the through-line group 45. Among them, the through-lines in the second edge region 131 and its vicinity include the fourth through-line 109 and the through-line group 45 closest to it.

[0086] In addition, Figure 5 Taking the back-contact cell shown as 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 pitch between the fourth through-line 109 and the through-line group 45 closest to it, that is, the third pitch, refers to the distance between the fifth edge and the sixth edge along the second direction Y.

[0087] In an example, referring to Figure 5 , the 2 cell substrates 101 can be distributed in an approximately axisymmetric manner along the adjacent junction of the 2 cell substrates 101, and the grid lines and through-lines on the 2 cell substrates 101 can also be distributed in an approximately axisymmetric manner. Among them, the grid lines include the first main grid 102, the second main grid 103, the first fine grid 106, and the second fine grid 107, and the through-lines include the first through-line 104, the second through-line 105, the third through-line 108, and the fourth through-line 109.

[0088] In some cases, referring to Figure 1 or Figure 5, the back contact battery may further include: a plurality of first pads 119, each first part 112 being in contact connection with at least one first pad 119; a plurality of second pads 129, each second part 113 being in contact connection with at least one second pad 129; on at least a part of the battery substrate 101, in the direction from the first edge region 111 to the central region 121, the number of first pads 119 between different adjacent through-line groups 45 gradually increases, and / or the number of second pads 129 between different adjacent through-line groups 45 gradually increases.

[0089] It should be noted that, based on the different polarities of the first part 112 and the second part 113, the pads also correspond to two polarities respectively, 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 central region 121, the spacing between different adjacent through-line groups 45 gradually increases, so that more first pads 119 and second pads 129 can be accommodated between the adjacent through-line groups 45 with a larger spacing, to ensure that enough first pads 119 are arranged on the first main grid 102, and enough second pads 129 are arranged on the second main grid 103, so as to ensure a large enough contact area between the solder tape and the first main grid 102 and the second main grid 103, thereby ensuring the current collection effect of the solder tape on the first main grid 102 and the second main grid 103.

[0090] It should be noted that Figure 1 and Figure 5 both take the example that between the group of through-line groups 45 closest to the first edge region 111, 2 first pads 119 are arranged on one first part 112 and 2 second pads 129 are arranged on one second part 113; and Figure 1 and Figure 5 both take the example that between other groups of through-line groups 45, 3 first pads 119 are arranged on one first part 112 and 3 second pads 129 are arranged on one second part 113. In actual applications, the number of first pads and second pads between adjacent through-line groups can be flexibly adjusted according to requirements.

[0091] In some embodiments, with reference to Figure 1 and Figure 6 , Figure 6 is Figure 1 a partial cross-sectional schematic diagram of the back contact battery shown in the direction of the first cross-section AA1. The battery substrate 101 includes a substrate 141 and a passivation layer 151 on the surface of the substrate 141, and both the first through-line 104 and the second through-line 105 are partially embedded in the passivation layer 151.

[0092] Thus, the first through-line 104 can not only be used to electrically connect multiple first parts 112 into a whole to achieve uniform current flow in the back-contact battery, but also collect photo-generated carriers generated in the substrate 141 like the fine grid, improving the collection efficiency of photo-generated carriers in the substrate 141 to enhance the photoelectric conversion efficiency of the back-contact battery. Similarly, the second through-line 105 can not only be used to electrically connect multiple second parts 113 into a whole to achieve uniform current flow in the back-contact battery, but also collect photo-generated carriers generated in the substrate 141 like the fine grid, improving the collection efficiency of photo-generated carriers in the substrate 141 to enhance the photoelectric conversion efficiency of the back-contact battery. Among them, the fine grid includes a first fine grid 106 and a second fine grid 107.

[0093] 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 paste used to prepare the first through-line 104 and the second through-line 105 is the same as the paste used to prepare the fine grid, and the first through-line 104 and the second through-line 105 are both composed of burn-through paste, so that the first through-line 104 and the second through-line 105 also penetrate the passivation layer 151. Thus, not only can the first through-line 104 be used to electrically connect multiple first parts 112 into a whole, and the second through-line 105 be used to electrically connect multiple second parts 113 into a whole, but also the first through-line 104 and the second through-line 105 can both collect photo-generated carriers in the substrate 141 by themselves, thereby increasing the collection path of photo-generated carriers and enhancing the photoelectric conversion efficiency of the back-contact battery.

[0094] In some cases, the passivation layer 151 can be a single-layer film structure or a stacked film structure, and the material of the passivation layer 151 can include at least one of materials such as silicon oxide, silicon nitride, silicon oxynitride, carbon oxynitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0095] In some cases, the substrate 141 has a first surface and a second surface arranged oppositely, and the first surface has a textured structure. The textured structure can increase the internal reflection of incident light to reduce optical losses and improve the photoelectric conversion efficiency of the back-contact battery.

[0096] In some examples, the first surface has a front surface field (FSF) whose doping ions have the same conductivity type as those of the substrate 141. The field passivation effect is utilized to reduce the surface minority carrier concentration, thereby reducing the surface recombination rate. At the same time, the series resistance can also be reduced, and the current transmission ability can be improved. The first surface also has a first passivation layer and a first antireflection layer. The first passivation layer is located on the surface of the front surface field, and the first antireflection 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 the front surface field, the first passivation layer, and the first antireflection layer.

[0097] In some examples, the second surface has alternately arranged first regions and second regions. The first region is one of a P region or an N region, and the second region is the other of a P region or an N region. There is a spacer gap between the P region and the N region; in other examples, there may not be a spacer gap between the P region and the N region, and an insulating film layer is provided 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 grid 106 and the second fine grid 107. Among them, the first fine grid 106 can be located on one of the first region and the second region, and the second fine grid 107 can be located on the other of the first region and the second region.

[0098] In some examples, the spacer gap can be flush with the P region and the N region, that is, the substrate 141 is not etched, and insulation between the P region and the N region is achieved through some isolating film layers. The isolating film layer can be a passivation film layer or an intrinsic semiconductor layer; in other examples, the spacer gap can be lower than the P region and the spacer gap can be lower than the N region. The spacer gap has a trench that extends from the second surface towards the first surface. The trench is used to achieve automatic isolation between regions of different conductivity types, and can eliminate leakage current generated by the formation of a PN junction between the heavily doped P region and N region in the back contact battery, which affects the battery efficiency.

[0099] In some examples, the surface of the spacer gap can be a polished surface structure or a textured surface structure.

[0100] In some examples, the P region and the N region can respectively have a tunneling silicon oxide layer and a doped polysilicon layer. Among them, 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 can respectively have an intrinsic amorphous silicon layer, a doped amorphous silicon layer, and a transparent conductive layer. Among them, the P region has a P-type doped amorphous silicon layer, and the N region has an N-type doped amorphous silicon layer.

[0101] In some examples, a second passivation layer and a second anti-reflection layer are provided on the P region, the N region, and the spacer gap. The first fine grid 106 and the second fine grid 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 aforementioned passivation layer 151.

[0102] In other embodiments, the materials of both the first through-line and the second through-line may also be the same as the material of the first main grid. For example, the paste used to prepare the first through-line and the second through-line is the same as the paste used to prepare the first main grid. The first through-line and the second through-line and the first main grid are all composed of non-burn-through paste. The first through-line and the second through-line are both located on the surface of the passivation layer and not embedded in the passivation layer. In this way, there is no need to perform layout settings on the first region and the second region of the substrate surface below the first through-line and the second through-line to prevent electrical contact between the first through-line and the second through-line and the doping regions of the other polarity, resulting in a short-circuit problem. In addition, the first through-line and the second through-line may not damage the passivation layer, thereby ensuring the integrity of the film layer of the passivation layer, improving the passivation effect of the passivation layer on the substrate, being beneficial to reducing the optical loss of the back-contact battery, and thus improving the photoelectric conversion efficiency of the back-contact battery. In addition, since the non-burn-through paste does not have too much glass powder to damage the PN junction, it can effectively reduce the metal recombination, improve the open-circuit voltage of the back-contact battery, and increase the conversion efficiency of the back-contact battery.

[0103] It should be noted that traditional paste may include a mixture of metal powder, glass powder, and organic carrier. Non-burn-through paste refers to a paste in which the content of glass powder contained in the paste is lower than that of traditional paste. During the sintering process, it has weak burn-through ability and does not require or cannot burn through the passivation layer. Burn-through paste refers to a paste that has strong burn-through ability and can burn through the passivation layer during the sintering process.

[0104] In practical applications, the first through-line and the second through-line may also be some film layers or conductive wires with conductive materials, as long as the first through-line electrically connects multiple first parts into a whole, and the second through-line electrically connects multiple second parts into a whole.

[0105] In some embodiments, refer to Figure 3In the second direction Y, the interval D1 between adjacent first parts 112 may be 10 mm to 12 mm. For example, it may be 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 break on the first main grid 102 is appropriate, so as to ensure that as many photo-generated carriers generated in the battery substrate 101 as possible are collected by the first main grid 102, thereby ensuring good photoelectric conversion efficiency of the back-contact battery.

[0106] In some embodiments, referring to Figure 4 In the second direction Y, the interval D2 between adjacent second parts 113 may be 10 mm to 12 mm. For example, it may be 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 break on the second main grid 103 is appropriate, so as to ensure that as many photo-generated carriers generated in the battery substrate 101 as possible are collected by the second main grid 103, thereby ensuring good photoelectric conversion efficiency of the back-contact battery.

[0107] In some embodiments, referring to Figure 1 、 Figure 2 or Figure 5 The battery substrate 101 is separated by 1 / N integral battery cells 100, where N is a positive integer greater than 1. The integral battery cell 100 includes a first edge region 161 and a second edge region 171 that are opposite in the first direction X; the back-contact battery may further include: a first edge connection line 139 located in the first edge region 161 and extending in the second direction Y; a second edge connection line 149 located in the second edge region 171 and extending in the second direction Y; the first edge connection line 139 is in contact connection with one of each first through line 104 and each second through line 105, and the second edge connection line 149 is in contact connection with the other of each first through line 104 and each second through line 105; 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. The edge connection line includes the first edge connection line 139 and the second edge connection line 149, and the through line includes the first through line 104 and the second through line 105.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] In summary, when the overall layout area on the back-contact battery remains unchanged, after the number of main grids increases, when at least a partial area on a certain first main grid 102 or second main grid 103 fails, the impact on the entire back-contact battery will be weakened. Based on this, designing a small number of through-wire groups 45 can achieve 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 enhance the anti-thermal-spot performance of the back-contact battery. Vice versa, after the number of main grids decreases, when at least a partial area on a certain first main grid 102 or second main grid 103 fails, 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 failure on the entire back-contact battery, so as to ensure a good current-sharing effect on the entire back-contact battery and ensure the good anti-thermal-spot performance of the back-contact battery. Therefore, on the basis of designing the through-wire group 45, the number of groups of the through-wire group 45 decreases as the number of main grids increases, which is beneficial to reducing the probability of the back-contact battery having a thermal-spot effect while reducing the costs required for manufacturing the first main grid 102, the second main grid 103, and the through-wire group 45.

[0113] Another embodiment of the present disclosure further provides a photovoltaic module. The photovoltaic module includes a plurality of photovoltaic cells provided in the foregoing embodiments, and the photovoltaic module is configured to convert the received light energy into electrical energy. It should be noted that for the same or corresponding parts as those in the foregoing embodiments, reference may be made to the corresponding descriptions in the foregoing embodiments, which will not be elaborated hereinafter.

[0114] With reference to Figures 1 to 6 and Figure 7 and Figure 8 the photovoltaic module includes: a battery string formed by connecting a plurality of the back-contact batteries 40 provided in the foregoing embodiments; an encapsulation adhesive film 41 for covering the surface of the battery string; and a cover plate 42 for covering the surface of the encapsulation adhesive film 41 facing away from the battery string. The back-contact batteries 40 are electrically connected in a whole-piece or multi-piece form to form a plurality of battery strings, and the plurality of battery strings are electrically connected in series and / or in parallel.

[0115] Wherein, Figure 7 is a partial three-dimensional schematic diagram of a photovoltaic module provided in another embodiment of the present disclosure, Figure 8 is Figure 7 a partial cross-sectional schematic diagram along the second cross-section direction BB1.

[0116] In some embodiments, with reference to Figure 7 and Figure 8 the plurality of back-contact batteries 40 can be electrically connected through a welding tape 43. Figure 7 and Figure 8Only the positional relationship between back contact cells is schematically shown. The grid lines of multiple adjacent back contact cells 40 can be located on the same side, and then the welding tape 43 connects the same side of two adjacent back contact cells 40. In other embodiments, the grid lines of multiple adjacent back contact cells can also be located on different sides, so that the welding tapes connect different sides of two adjacent back contact cells respectively.

[0117] In some embodiments, the encapsulation adhesive film 41 includes a first encapsulation layer and a second encapsulation layer. The first encapsulation layer covers one of the front or back surfaces of the back contact cell 40, and the second encapsulation layer covers the other of the front or back surfaces of the back contact cell 40. Specifically, at least one of the first encapsulation layer or the second encapsulation layer can be an organic encapsulation adhesive film such as a polyvinyl butyral (PVB) adhesive film, an ethylene-vinyl acetate copolymer (EVA) adhesive film, a polyethylene octene co-elastic body (POE) adhesive film, or a polyethylene terephthalate (PET) adhesive film. Or, at least one of the first encapsulation layer or the second encapsulation layer can also be an adhesive film such as an EP adhesive film, an EPE adhesive film, or a PVP adhesive film. Among them, the EP adhesive film refers to a co-extruded adhesive film composed of an EVA adhesive film and a POE adhesive film arranged in a laminated manner. The EPE adhesive film refers to a co-extruded adhesive film formed by sequentially laminating an EVA adhesive film + a POE adhesive film + an EVA adhesive film. The PVP adhesive film refers to a co-extruded adhesive film formed by laminating a POE adhesive film + an EVA adhesive film + a POE adhesive film. The preparation method of the co-extruded adhesive film can be, during the processing of the adhesive film, extruding one or more raw materials onto another already made adhesive film in sequence, or bonding different types of already made adhesive films together.

[0118] In some cases, there is still a demarcation line between the first encapsulation layer and the second encapsulation layer before lamination. After the lamination treatment, 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 adhesive film 41.

[0119] 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 adhesive film 41 can be a concave-convex surface or a velvet surface including a plurality of protruding structures, so as to increase the utilization rate of incident light. The cover plate 42 includes a first cover plate and a second cover plate. The first cover plate is opposite to the first encapsulation layer, and the second cover plate is opposite to the second encapsulation layer.

[0120] In some cases, when the back contact cell 40 is a cell with main grids, 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. Refer to Figure 1 、 Figure 2 or Figure 5, the main grid includes a first main grid 102 and a second main grid 103. With reference to 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 by using the back-contact battery 40, the welding tape 43 is electrically connected to at least one main grid on each of the two adjacent back-contact batteries 40.

[0121] Those of ordinary skill in the art can understand that the above embodiments are specific examples for implementing the present disclosure. In practical applications, various changes can be made to its 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 should be subject to the scope defined by 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 which 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: The number of the main grids is greater than or equal to 18, and the number of the through-line groups is less than 4.

4. The back contact cell according to claim 1, characterized in that: Along the second direction, the width of at least one of the first penetration line and the second penetration line decreases as the number of the main gates increases.

5. The back contact cell according to claim 4, 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.

6. 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.

7. The back contact cell according to claim 6, 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.

8. The back contact battery according to claim 7, 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.

9. The back contact battery according to claim 6, 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.

10. The back contact cell according to claim 6, 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.

11. 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.

12. The back contact cell according to claim 1, characterized in that: Along the second direction, an interval between adjacent first portions is 10 mm to 12 mm; and / or, along the second direction, an interval between adjacent second portions is 10 mm to 12 mm.

13. 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 12; 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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