Back contact battery and photovoltaic module

Abstract

The invention discloses a back contact battery and a photovoltaic module, and the back contact battery comprises a battery body, at least one electrode pattern region, a plurality of first current collection grid lines, a plurality of second current collection grid lines, a plurality of first confluence part groups and a plurality of second confluence part groups, each first confluence part group comprises a plurality of first confluence parts and a plurality of first connecting parts which are alternately distributed in the second direction, the first confluence parts are electrically connected with the first collector grid lines, the first connecting parts are electrically connected with the second collector grid lines, and the plurality of first confluence part groups comprise middle first confluence part groups and edge first confluence part groups; the number of the first connecting parts in the edge first confluence part group is smaller than the number of the first connecting parts in the middle first confluence part group. In the embodiment of the invention, the probability of contact between the interconnection piece and the opposite electrodes caused by deviation of the insulating layer close to the edge of the battery piece can be reduced, so that the risk of short circuit can be reduced.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202510863578.8, filed on June 25, 2025, entitled “A Back Contact Battery and a Photovoltaic Module”, the contents of which are incorporated herein by reference in part. Technical Field

[0003] This invention relates to the field of photovoltaic technology, and more particularly to a back-contact battery and photovoltaic module. Background Technology

[0004] In a back-contact battery, both the positive and negative electrodes are located on the back side, with no grid lines obstructing the front side, in order to reduce optical loss and improve power generation efficiency.

[0005] To reduce paste consumption and minimize grid line shading of the back contact cell, a gridless back contact cell was developed, where the solder ribbon is directly electrically connected to the fine grid. The fine grid is typically designed as multiple broken segments, with the breaks connected by a connecting structure.

[0006] In back-contact batteries, an insulating layer is placed between the solder ribbon and the non-linear connection structure. The closer to the edge of the back-contact battery, the more difficult it is to align the insulating layer and the printed current collector grid lines during the connection process. Misalignment can easily lead to difficulties in carrier collection or short circuits. Summary of the Invention

[0007] This invention provides a back-contact battery and a photovoltaic module, aiming to at least solve the technical problem that carrier collection difficulties or short circuits are likely to occur at the edge of the back-contact battery.

[0008] This invention provides a back contact battery, comprising:

[0009] The battery body includes the back side and the second surface of the battery cells disposed opposite to each other;

[0010] At least one electrode pattern area is disposed on the back side of the solar cell;

[0011] Multiple first collector grid lines and multiple second collector grid lines are disposed within the electrode pattern area, and extend along a first direction and are alternately distributed along a second direction. The first direction and the second direction intersect, and the first collector grid lines and the second collector grid lines have different polarities.

[0012] Multiple first busbar groups and multiple second busbar groups are disposed at least in the middle portion of the electrode pattern area and are alternately distributed along the first direction;

[0013] The first busbar group includes a plurality of first busbars and a plurality of first connecting parts that are alternately distributed along the second direction. The first busbars are electrically connected to the first collector grid lines, and the first connecting parts are electrically connected to the second collector grid lines.

[0014] The second busbar group includes a plurality of second busbars and a plurality of second connecting parts that are alternately distributed along the second direction. The second busbars are electrically connected to the second collector grid lines, and the second connecting parts are electrically connected to the first collector grid lines.

[0015] The plurality of first busbar groups include an intermediate first busbar group and an edge first busbar group, wherein the number of first connecting parts in the edge first busbar group is less than the number of first connecting parts in the intermediate first busbar group.

[0016] In this embodiment of the invention, the number of first connectors in the edge first busbar group near the edge of the battery cell is reduced, and the second current collector line extends continuously at the position after removing the first connectors. At this time, the second current collector line, not the first connector, lies beneath the insulating layer provided at the edge first busbar group. Compared to the first connector, the width of the second current collector line is smaller, which reduces the probability of the interconnect contacting the opposite electrode due to the offset of the insulating layer near the edge of the battery cell, thereby reducing the risk of short circuits. Furthermore, since the probability of a short circuit when the intermediate first busbar group connects to the interconnect is extremely small, not reducing the number of first connectors in the intermediate first busbar group ensures the bonding strength between the interconnect and the intermediate first busbar group.

[0017] In this embodiment of the invention, the number of first connecting portions is reduced in the first edge busbar group near the edge of the solar cell. The second current collector line extends continuously after the first connecting portions are removed. This reduces the need for the portion of the second current collector line near the edge of the solar cell to overlap with the first connecting portions, thus reducing the risk of difficulty in collecting edge carriers due to overlap offset, or even the risk of being unable to collect edge carriers. Furthermore, since the first edge busbar group is close to the edge of the solar cell, even without a break in the second current collector line at this point and a connection point between the second current collector line and the first connecting portion, the lifespan of the screen printing plate during the screen printing process can still be better guaranteed.

[0018] Optionally, the intermediate first confluence group includes a plurality of first confluences and a plurality of first connecting parts that are alternately distributed along the second direction, and the edge first confluence group is composed of first confluences arranged along the second direction.

[0019] Optionally, the electrode pattern area has a first side and a second side disposed opposite to each other along the second direction, and there is no discontinuity between the first collector grid line and the first side of the edge first busbar group;

[0020] And / or, between the first collector grid line and the second side, there is no discontinuity between the first collector grid line and the second collector grid line.

[0021] Optionally, the electrode pattern area has a third side and a fourth side disposed opposite to each other along the first direction;

[0022] The first busbar group at the edge is the first busbar group closest to the third side in the electrode pattern area, and the second collector grid line electrically connected to the second busbar group extends continuously from the third side to the second busbar group adjacent to the first busbar group at the edge.

[0023] Optionally, the electrode pattern area has a third side and a fourth side disposed opposite to each other along the first direction;

[0024] The first busbar group at the edge is the first busbar group closest to the third side in the electrode pattern area, and the first collector grid line electrically connected to the first busbar group extends continuously from the third side to the second busbar group adjacent to the first busbar group at the edge.

[0025] Optionally, the plurality of second bus groups include a middle second bus group and an edge second bus group, the electrode pattern area has a third side and a fourth side disposed opposite to each other along the first direction, the edge first bus group is the first bus group in the electrode pattern area that is closest to the third side, and the edge second bus group is the second bus group in the electrode pattern area that is closest to the fourth side.

[0026] The number of second connecting portions in the edge second busbar group is less than the number of second connecting portions in the middle second busbar group and / or the number of first connecting portions in the middle first busbar group.

[0027] Optionally, the battery body includes an N-type doped layer and a P-type doped layer, the first current collector line is disposed on the N-type doped layer, the N-type doped layer and the P-type doped layer extend along the first direction and are alternately distributed along the second direction; when the second current collector line is disposed on the P-type doped layer, the ratio of the width of the first current collector in the first current collector group to the width of the corresponding N-type doped layer is greater than the ratio of the width of the second current collector in the second current collector group to the width of the corresponding P-type doped layer;

[0028] And / or, the ratio of the width of the first connector in the first busbar group to the width of the N-type doped layer at the corresponding position is greater than the ratio of the width of the second connector in the second busbar group to the width of the P-type doped layer at the corresponding position.

[0029] Optionally, the size of the first busbar is larger than the size of the first connector.

[0030] Optionally, the electrode pattern area has a first side and a second side disposed opposite to each other along a second direction, and the electrode pattern area includes a middle region and an edge region located between the middle region and the first side or the second side;

[0031] The edge region is provided with a plurality of welding parts, the plurality of welding parts including a first welding part. Along the second direction, a first welding part is provided between one of the intermediate first confluence groups and the first side, and a first welding part is provided between one of the intermediate first confluence groups and the second side. The first welding part includes a first rectangular part and a first end line.

[0032] Optionally, the dimension of the first rectangular portion along the second direction is larger than the dimension of the first confluence portion along the second direction.

[0033] Optionally, the first end line extends along the second direction, and the first end line is electrically connected to the first collector grid line in the edge region through the third connecting portion;

[0034] The first collector grid line in the edge region is provided with a third discontinuity corresponding to the third connection portion. Along the first direction, the length of the third discontinuity is greater than the width of the first end line and less than the length of the third connection portion.

[0035] Optionally, along the first direction, the second collector grid line in the edge region forms a fourth discontinuity at the first end line, and the length of the fourth discontinuity is greater than the length of the third discontinuity.

[0036] Optionally, the electrode pattern area has a first side and a second side disposed opposite to each other along a second direction, and the electrode pattern area includes a middle region and an edge region located between the middle region and the first side or the second side;

[0037] Along the first direction, the first collector grid line in the intermediate region is provided with a first discontinuity, and the second collector grid line in the intermediate region is provided with a second discontinuity.

[0038] Optionally, the length of the first discontinuity is greater than 0 mm and less than or equal to 0.4 mm, and / or the length of the second discontinuity is greater than 0 mm and less than or equal to 0.4 mm.

[0039] Optionally, along the first direction, on the same first collector grid line, two adjacent first discontinuity regions correspond to the first busbar and the second connection, respectively;

[0040] In the same intermediate first busbar group, the length of the first discontinuity zone corresponding to the first busbar is greater than or equal to the length of the second discontinuity zone corresponding to the first connecting part.

[0041] Optionally, along the first direction, in the first bus group, the overlap rate between the first collector grid line and the first bus is greater than or equal to the overlap rate between the second collector grid line and the first connection.

[0042] Optionally, along the first direction, the overlap rate between the second collector grid line and the first connection portion is 30%-65%;

[0043] And / or, along the first direction, the overlap rate between the first collector grid line and the first bus is 50%-80%.

[0044] Optionally, the material of the first busbar is the same as the material of the first connector, and the material of the first busbar is different from the material of the first collector grid line or the second collector grid line.

[0045] Optionally, the first busbar is rectangular or elliptical in shape;

[0046] The shape of the first connecting part is I-shaped, rectangular, elliptical, trapezoidal or spindle-shaped.

[0047] This invention also provides a photovoltaic module, including multiple battery strings, each battery string including multiple back contact cells as described above and multiple interconnecting elements, wherein the interconnecting elements connect two adjacent back contact cells in series or in parallel;

[0048] The interconnecting component is electrically connected to the first busbar and the second busbar through a conductive layer, and the interconnecting component is insulated from the first connection and the second connection through an insulating layer.

[0049] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of the present invention more obvious and understandable, specific embodiments of the present invention are given below. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the structure of one of the electrode pattern areas in a back contact battery provided in an embodiment of the present invention;

[0051] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0052] Figure 3 for Figure 1 Enlarged view of point B in the middle;

[0053] Figure 4 for Figure 1 Enlarged view of point C in the middle;

[0054] Figure 5 for Figure 1 Enlarged view of point D in the middle;

[0055] Figure 6 for Figure 1 Enlarged view of point E in the middle;

[0056] Figure 7 for Figure 1 Enlarged view of point F in the middle;

[0057] Figure 8 for Figure 7 Enlarged view of point G in the middle;

[0058] Figure 9 for Figure 7 Enlarged view of point H in the middle;

[0059] Figure 10 This is a schematic diagram showing the overlap of the first current collector grid line and the first current bus in a back contact battery provided in an embodiment of the present invention, and the overlap of the second current collector grid line and the first connection portion.

[0060] Figure 11 This is a schematic diagram of the structure of a first connection portion in a back contact battery provided in an embodiment of the present invention;

[0061] Figure 12 This is a schematic diagram of another type of first connection portion in a back contact battery provided in an embodiment of the present invention.

[0062] Figure label:

[0063] 11-First collector grid line, 12-Second collector grid line, 21-Edge first bus group, 22-Middle first bus group, 23-First bus, 24-First connecting part, 31-Edge second bus group, 32-Middle second bus group, 33-Second bus, 34-Second connecting part, 40-First welding part, 41-First rectangular part, 42-First end line, 50-Second welding part, 51-Second rectangular part, 52-Second end line; 61-Third connecting part, 62-Fourth connecting part, 70-Edge connecting part. Detailed Implementation

[0064] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0065] Reference Figure 1 and Figure 2 This invention provides a back-contact battery, specifically a gridless battery cell. The back-contact battery includes a battery body, at least one electrode pattern area, multiple first current collector lines 11 and multiple second current collector lines 12, multiple first busbar groups, and multiple second busbar groups.

[0066] The battery body includes a back surface of a battery cell and a second surface that are disposed opposite to each other. Specifically, the back surface of the battery cell and the second surface are disposed opposite to each other along the thickness direction of the battery cell body. The back surface of the battery cell can be a backlight surface, and the second surface is a light-facing surface.

[0067] The back-contact battery includes at least one electrode pattern area disposed on the back side of the cell. Multiple first current collector lines 11, multiple second current collector lines 12, multiple first busbar groups, and multiple second busbar groups are all disposed within the electrode pattern area. The electrode pattern area is an independent functional unit that conducts current from inside the battery to the outside of the battery through interconnects. For example, multiple electrode pattern areas can be disposed on the entire cell, with gaps between adjacent electrode pattern areas. After segmentation at the gaps, each segment of the cell has an independent electrode pattern area.

[0068] The first collector grid line 11 and the second collector grid line 12 are both disposed within the electrode pattern area on the back side of the back contact battery. Both the first collector grid line 11 and the second collector grid line 12 extend along a first direction, meaning their length directions are aligned with the first direction. Multiple first collector grid lines 11 and multiple second collector grid lines 12 are alternately distributed along a second direction. The first collector grid lines 11 and the second collector grid lines 12 have different polarities to facilitate the extraction of current collected by the battery body. The first direction intersects the second direction; preferably, the first direction is perpendicular to the second direction. Specifically, the first direction can be referred to... Figures 1 to 7 The direction indicated by the X arrow in the middle; the second direction can be referenced. Figures 1 to 7 The direction indicated by the Y-arrow in the middle.

[0069] Multiple first busbar groups and multiple second busbar groups are disposed at least in the middle portion of the electrode pattern area. The electrode pattern area has a first side and a second side disposed opposite to each other along a second direction, and includes a middle region and an edge region located between the middle region and the first side or the second side. The middle portion of the electrode pattern area is also the middle region of the electrode pattern area. Figure 1 In the diagram, the first edge is specifically the upper edge of the electrode pattern area, and the second edge is specifically the lower edge of the electrode pattern area. The boundary between the middle area and the edge area can be seen from the dashed line S in the diagram.

[0070] Each first busbar group contains multiple first busbars and multiple first connectors arranged in a row along the second direction, and each second busbar group contains multiple second busbars and multiple second connectors arranged in a row along the second direction.

[0071] Multiple first busbar groups and multiple second busbar groups are arranged alternately along a first direction. Each first busbar group includes multiple first busbars 23 and multiple first connecting parts 24, which are alternately distributed along a second direction. The first busbars 23 are electrically connected to first collector lines 11, and the first connecting parts 24 are electrically connected to second collector lines 12. Each second busbar group includes multiple second busbars 33 and multiple second connecting parts 34, which are alternately distributed along a second direction. The second busbars 33 are electrically connected to second collector lines 12, and the second connecting parts 34 are electrically connected to first collector lines 11.

[0072] Each first bus 23 is electrically connected to the first collector grid line 11, and each first connection 24 is electrically connected to the second collector grid line 12. Each second connection 34 is electrically connected to the first collector grid line 11, and each second bus 33 is electrically connected to the second collector grid line 12. Both the first bus 23 and the second bus 33 are used for electrical connection to interconnects. The current collected by the first collector grid line 11 can be transmitted to the interconnect via the first bus 23, and the current collected by the second collector grid line 12 can be transmitted to the interconnect via the second bus 33. Both the first connection 24 and the second connection 34 are used for insulated connection to the interconnect via an insulating layer.

[0073] The interconnecting component extends along the second direction. While the interconnecting component is electrically connected to the first busbar 23 in the first busbar group, an insulating layer is provided between the interconnecting component and the first connection portion 24 to prevent short circuit. While the interconnecting component is electrically connected to the second busbar 33 in the second busbar group, an insulating layer is provided between the interconnecting component and the second connection portion 34 to prevent short circuit.

[0074] The multiple first bus groups include a middle first bus group 22 and an edge first bus group 21. The edge first bus group 21 is the first bus group closest to the edge of the electrode pattern area. Among the multiple first bus groups, all the other first bus groups except the edge first bus group 21 are the middle first bus group 22.

[0075] An electrode pattern area has two busbar groups closest to the edge. These two busbar groups can both be the first busbar group, or both be the second busbar group, or one can be the first busbar group and the other can be the second busbar group.

[0076] For example, the electrode pattern area has a third side and a fourth side arranged opposite to each other along a first direction, and the first busbar group 21 at the edge is the first busbar group in the electrode pattern area that is closest to the third side and / or the fourth side. Figure 1 In this context, the third side specifically refers to the left edge of the electrode pattern area, and the fourth side specifically refers to the right edge of the electrode pattern area. In one embodiment, the busbar group closest to the third side in the electrode pattern area is the first edge busbar group 21, and the busbar group closest to the fourth side in the electrode pattern area is the second edge busbar group 31. In another embodiment, the busbar groups closest to both the third and fourth sides in the electrode pattern area are both the first edge busbar group 21. In other embodiments, the busbar groups closest to both the third and fourth sides in the electrode pattern area are both the second edge busbar group 31.

[0077] The number of first connecting portions 24 in the edge first busbar group 21 is less than the number of first connecting portions 24 in the intermediate first busbar group 22. When the number of first connecting portions 24 in the edge first busbar group 21 is reduced to 0, the edge first busbar group 21 does not include the first connecting portions 24, but only includes the first busbars 23. At this time, only the intermediate first busbar group 22 includes multiple first busbars 23 and multiple first connecting portions 24 that are alternately distributed along the second direction. That is, only a portion of the first busbar groups include multiple first busbars 23 and multiple first connecting portions 24 that are alternately distributed along the second direction, rather than all the first busbar groups including multiple first busbars 23 and multiple first connecting portions 24 that are alternately distributed along the second direction.

[0078] When the number of first connecting portions 24 in the edge first busbar group 21 is greater than 0, both the edge first busbar group 21 and the middle first busbar group 22 include first connecting portions 24. Preferably, the number of first connecting portions 24 in the edge first busbar group 21 is less than half the number of first connecting portions 24 in the middle first busbar group 22. Preferably, the first connecting portions 24 at both ends along the second direction in the edge first busbar group 21 are removed. It should be noted that in the edge first busbar group 21, the first busbar 23 is arranged alternately with the first connecting portion 24 only in the area where the first connecting portion 24 is retained.

[0079] In some embodiments, the first collector line 11, the second collector line 12, the first busbar 23, the first connector 24, the second busbar 33, and the second connector 34 can all be printed by screen printing. Specifically, a paste is used for printing, and the paste types include silver paste, copper paste, and silver-nickel mixed paste.

[0080] In the actual manufacturing process of back contact batteries, the grid lines of the back contact batteries are generally printed using PI (polyimide) screen printing. However, PI screen printing has a short lifespan, and the printing quality is poor in low-humidity environments, resulting in a low product yield. In this embodiment of the invention, a steel plate screen printing can be used instead of the PI screen printing for grid line printing. The steel plate screen printing has a longer lifespan and is less affected by environmental humidity and temperature.

[0081] In the first busbar group 21 at the edge, the position after removing the first connecting part 24 allows the second collector grid line 12 to extend continuously. The second collector grid line 12 is insulated from the interconnecting member through an insulating layer to prevent short circuit.

[0082] The busbar groups near the edge of the solar cell are more difficult to align during the insulation layer installation process, and are more prone to misalignment. Misalignment of the insulation layer can easily lead to short circuits when connecting interconnects. In this embodiment of the invention, the number of first connecting portions 24 in the edge first busbar group 21 near the edge of the solar cell is reduced, and the second current collector line 12 extends continuously in the position after removing the first connecting portions 24. At this time, the second current collector line 12, not the first connecting portion 24, is below the insulation layer provided at the edge first busbar group 21. Compared with the first connecting portion 24, the width of the second current collector line 12 is smaller, which can reduce the probability of contact between the interconnect and the opposite electrode caused by the misalignment of the insulation layer near the edge of the solar cell, thereby reducing the risk of short circuit. In addition, since the probability of short circuit when connecting the intermediate first busbar group 22 to the interconnect is extremely small, the number of first connecting portions 24 in the intermediate first busbar group 22 is not reduced, which can ensure the bonding force between the interconnect and the intermediate first busbar group 22.

[0083] The busbar group near the edge of the solar cell is more prone to misalignment during the overlap of the current collector grid lines with the connecting parts or the busbars. Misalignment at the overlap position can lead to ineffective collection of charge carriers at the edge of the solar cell, reducing battery efficiency. In this embodiment of the invention, the number of first connecting parts 24 in the first busbar group 21 near the edge of the solar cell is reduced. After removing the first connecting parts 24, the second current collector grid line 12 extends continuously. This reduces the need for the portion of the second current collector grid line 12 near the edge of the solar cell to overlap with the first connecting parts 24, reducing the risk of difficulty in collecting charge carriers at the edge of the solar cell due to overlap misalignment, or even the risk of not being able to collect charge carriers at the edge of the solar cell. In addition, since the first busbar group 21 is close to the edge of the solar cell, even if the second current collector grid line 12 is not disconnected at this point and connected to the disconnection point of the second current collector grid line 12 by the first connecting part 24, the lifespan of the screen printing plate during the screen printing process can still be better guaranteed.

[0084] In some embodiments, refer to Figure 2 The intermediate first bus group 22 includes a plurality of first bus sections 23 and a plurality of first connecting sections 24 alternately distributed along the second direction, and the edge first bus group 21 is composed of first bus sections 23 arranged along the second direction. In this embodiment, the number of first connecting sections 24 in the edge first bus group 21 is 0, that is, the edge first bus group 21 does not include first connecting sections 24, which can further reduce the risk of short circuit when the edge first bus group 21 is connected to the interconnect. In addition, in terms of printing integrity, it can avoid the occurrence of incomplete printing when the first connecting section 24 overlaps with the second collector line 12 at the edge position, thereby reducing the incidence of printing defects.

[0085] In some embodiments, refer to Figure 3 Between the first busbar group 21 and the first side, there is no discontinuity in the first collector grid line 11 and the second collector grid line 12; refer to Figure 4 Between the first busbar group 21 and the second side, there is no discontinuity in the first collector grid line 11 and the second collector grid line 12. It should be noted that the absence of a discontinuity means that the first collector grid line 11 and the second collector grid line 12 are printed as a single piece in this area during the printing process. That is, the first collector grid line 11 and the second collector grid line 12 in this area extend continuously along the second direction toward the fourth side until they break at the second welding part 50.

[0086] No end lines, discontinuities, or connections are provided between the edge first busbar group 21 and the first side. Similarly, no end lines, discontinuities, or connections are provided between the edge first busbar group 21 and the second side. In the areas containing the middle first busbar group 22, the middle second busbar group 32, the first welded part 40, and the second welded part 50, discontinuities are provided for the first collector grid line 11 and the second collector grid line 12 to alleviate stress concentration caused by thermal expansion or mechanical loads and reduce the risk of microcracks. In screen printing, when using a steel plate screen, the discontinuities of the first collector grid line 11 and the second collector grid line 12 form support sections for the open areas on the screen, which can better enhance the support of the steel plate screen during printing, reduce damage to the screen caused by stress during printing, increase the lifespan of the screen, and reduce the manufacturing cost of the solar cells. At the corners of the back contact battery, the connection part is more likely to be poorly printed. In this embodiment, the connection part at the corner of the back contact battery is eliminated, and the current collection grid line is made continuous at the corner of the back contact battery. Without affecting the overall relief of stress concentration caused by thermal expansion and mechanical load or the service life of the steel plate screen, the occurrence rate of printing defects can be further reduced, and the effective collection of current at the corner of the back contact battery can be guaranteed.

[0087] In some embodiments, refer to Figure 3 and Figure 4 The edge first bus group 21 is the first bus group closest to the third side in the electrode pattern area. The second collector grid line 12, which is electrically connected to the second bus group, extends continuously from the third side to the second bus group adjacent to the edge first bus group 21, and is disconnected at the second bus group. It is also disconnected or thickened at the middle first bus group 22.

[0088] Specifically, the second bus group adjacent to the edge first bus group 21 is the middle second bus group 32. The second collector grid line 12 electrically connected to the second bus group is also the second collector grid line 12 located in the middle region. From the third to the fourth side of the electrode pattern area, the second collector grid line 12 electrically connected to the second bus group extends continuously at the edge first bus group 21, is interrupted or thickened at the middle first bus group 22, and is interrupted at the middle second bus group 32. In this embodiment, the second collector grid line 12 at the edge position extends continuously until it is interrupted at the second bus group adjacent to the edge first bus group 21, which has a good current collection effect at the edge position.

[0089] It should be noted that the aforementioned continuously extending second collector line 12 refers to the second collector line 12 being integrally printed between the third side and the edge first busbar group 21, without any discontinuities, other material portions, thickened portions, etc. When the second collector line 12 is broken at the middle first busbar group 22, the break can be connected by the first connecting portion 24. When the second collector line 12 is thickened at the middle first busbar group 22, the thickened section can serve as one type of first connecting portion 24.

[0090] In some embodiments, refer to Figure 3 and Figure 4 The edge first bus group 21 is the first bus group closest to the third side in the electrode pattern area. The first collector grid line 11 electrically connected to the first bus group extends continuously from the third side to the second bus group adjacent to the edge first bus group 21, and is interrupted or thickened at the second bus group, and is interrupted at the middle first bus group 22. Specifically, the second bus group adjacent to the edge first bus group 21 is the middle second bus group 32. The first collector grid line 11 electrically connected to the first bus group is also the first collector grid line 11 located in the middle region.

[0091] From the third to the fourth side of the electrode pattern area, the first current collector line 11, electrically connected to the first busbar group, extends continuously at the edge of the first busbar group 21, breaks off at the middle first busbar group 22, and breaks off or thickens at the middle second busbar group 32. In this embodiment, the first current collector line 11 at the edge extends continuously until it breaks off at the second busbar group adjacent to the edge of the first busbar group 21, which provides good current collection at the edge. In addition, the first current collector line 11 connected to the first busbar 23 of the edge first busbar group 21 is continuously arranged at the edge of the cell. During the electrical performance testing of the cell, it can better ensure the overlap between the probe in the testing device and the first current collector line 11 at the edge of the first busbar group 21, thus ensuring the testing effect.

[0092] It should be noted that the aforementioned continuously extending first collector line 11 refers to the first collector line 11 being integrally printed between the third side and the edge first busbar group 21, without any discontinuities, other material portions, thickened portions, etc. When the first collector line 11 is broken at the middle second busbar group 32, the break can be connected by the second connecting portion 34. When the first collector line 11 is thickened at the middle second busbar group 32, the thickened section can serve as one type of second connecting portion 34.

[0093] In some embodiments, refer to Figure 2 and Figure 5The multiple second bus groups include a middle second bus group 32 and an edge second bus group 31. The edge second bus group 31 is the second bus group closest to the edge of the electrode pattern area. Among the multiple second bus groups, all the other second bus groups except the edge second bus group 31 are the middle second bus group 32.

[0094] Specifically, the busbar group closest to the third side in the electrode pattern area is the first edge busbar group 21, and the busbar group closest to the fourth side in the electrode pattern area is the second edge busbar group 31. Between the first edge busbar group 21 and the second edge busbar group 31, multiple intermediate first busbar groups 22 and multiple intermediate second busbar groups 32 are alternately arranged along the first direction, with the intermediate second busbar group 32 adjacent to the first edge busbar group 21 and the intermediate first busbar group 22 adjacent to the second edge busbar group 31.

[0095] The number of second connecting portions 34 in the edge second bus group 31 is less than the number of second connecting portions 34 in the intermediate second bus group 32 and / or the number of first connecting portions 24 in the intermediate first bus group 22. When the number of second connecting portions 34 in the edge second bus group 31 is reduced to 0, the edge second bus group 31 does not include second connecting portions 34, but only includes second bus portions 33. At this time, only the intermediate second bus group 32 includes multiple second bus portions 33 and multiple second connecting portions 34 that are alternately distributed along the second direction. That is, only a portion of the second bus groups include multiple second bus portions 33 and multiple second connecting portions 34 that are alternately distributed along the second direction, rather than all the second bus groups including multiple second bus portions 33 and multiple second connecting portions 34 that are alternately distributed along the second direction.

[0096] When the number of second connecting portions 34 in the edge second busbar group 31 is greater than 0, both the edge second busbar group 31 and the intermediate second busbar group 32 include second connecting portions 34. Preferably, the number of second connecting portions 34 in the edge second busbar group 31 is less than half the number of second connecting portions 34 in the intermediate second busbar group 32. Preferably, the second connecting portions 34 at both ends along the second direction in the edge second busbar group 31 are removed. It should be noted that in the edge second busbar group 31, the second busbar 33 is arranged alternately with the second connecting portion 34 only in the area where the second connecting portion 34 is retained.

[0097] In the edge second bus group 31, the position after removing the second connecting part 34 allows the first collector grid line 11 to extend continuously. The first collector grid line 11 is insulated from the interconnecting member through an insulating layer to prevent short circuit.

[0098] The busbar groups near the edge of the solar cell are more difficult to align during the insulation layer installation process, and are more prone to misalignment. Misalignment of the insulation layer can easily lead to short circuits when connecting interconnects. In this embodiment of the invention, the number of second connecting portions 34 in the edge second busbar group 31 near the edge of the solar cell is reduced. After removing the second connecting portions 34, the first current collector line 11 extends continuously. At this time, for the insulation layer installed at the edge second busbar group 31, the first current collector line 11 is below the insulation layer, not the second connecting portion 34. Compared to the second connecting portion 34, the width of the first current collector line 11 is smaller, which can reduce the probability of contact between the interconnect and the opposite electrode caused by the misalignment of the insulation layer near the edge of the solar cell, thereby reducing the risk of short circuits. In addition, since the probability of short circuits when connecting the intermediate second busbar group 32 to the interconnect is extremely small, the number of second connecting portions 34 in the intermediate second busbar group 32 is not reduced, which can ensure the bonding force between the interconnect and the intermediate second busbar group 32.

[0099] The busbar group near the edge of the solar cell is more prone to misalignment during the overlap of the current collector grid lines with the connecting parts or the busbars. Misalignment at the overlap position can lead to ineffective collection of charge carriers at the edge of the solar cell, reducing battery efficiency. In this embodiment of the invention, the number of second connecting parts 34 in the edge second busbar group 31 near the edge of the solar cell is reduced. After removing the second connecting parts 34, the first current collector grid line 11 extends continuously. This reduces the need for the portion of the first current collector grid line 11 near the edge of the solar cell to overlap with the second connecting parts 34, reducing the risk of difficulty in collecting charge carriers at the edge of the solar cell due to overlap misalignment, or even the risk of not being able to collect charge carriers at the edge of the solar cell. In addition, since the edge second busbar group 31 is close to the edge of the solar cell, even if the first current collector grid line 11 is not disconnected at this point and connected to the disconnection point of the first current collector grid line 11 by the second connecting parts 34, the lifespan of the screen printing plate during the screen printing process can still be better guaranteed.

[0100] In some embodiments, refer to Figure 5 The intermediate second bus group 32 includes a plurality of second bus sections 33 and a plurality of second connecting sections 34 alternately distributed along the second direction, and the edge second bus group 31 is composed of second bus sections 33 arranged along the second direction. In this embodiment, the number of second connecting sections 34 in the edge second bus group 31 is 0, that is, the edge second bus group 31 does not include second connecting sections 34, which can further reduce the risk of short circuit when the edge second bus group 31 is connected to the interconnect. In addition, in terms of printing integrity, it can avoid the occurrence of incomplete printing when the second connecting section 34 overlaps with the first collector line 11 at the edge position, thereby reducing the incidence of printing defects.

[0101] In some embodiments, refer to Figure 5Between the second busbar group 31 and the first side, there is no discontinuity in the first collector grid line 11 and the second collector grid line 12; see reference. Figure 6 Between the second busbar group 31 and the second side, there is no discontinuity in the first collector grid line 11 and the second collector grid line 12. It should be noted that the absence of a discontinuity means that the first collector grid line 11 and the second collector grid line 12 are printed as a single piece in this area during the printing process. That is, the first collector grid line 11 and the second collector grid line 12 in this area extend continuously along the second direction toward the third side until they break at the first welding part 40.

[0102] No end lines, discontinuities, or connecting parts are provided between the edge second busbar group 31 and the first side. Similarly, no end lines, discontinuities, or connecting parts are provided between the edge second busbar group 31 and the second side. At the corners of the back contact battery, the probability of incomplete printing at the connecting parts is relatively high. In this embodiment, the connecting parts at the corners of the back contact battery are eliminated, ensuring continuous current collection at the corners. This further reduces the incidence of printing defects and guarantees effective current collection at the corners of the back contact battery without affecting the overall mitigation of stress concentration caused by thermal expansion and mechanical loads, or the service life of the steel screen.

[0103] In some embodiments, refer to Figure 5 and Figure 6 The edge second bus group 31 is the second bus group closest to the fourth side in the electrode pattern area. The first collector grid line 11, which is electrically connected to the first bus group, extends continuously from the fourth side to the first bus group adjacent to the edge second bus group 31, and is disconnected at the first bus group. It is also disconnected or thickened at the middle second bus group 32. The first bus group adjacent to the edge second bus group 31 is the middle first bus group 22. The first collector grid line 11 electrically connected to the first bus group is also the first collector grid line 11 located in the middle region.

[0104] Specifically, the first collector grid line 11, electrically connected to the first bus group, extends continuously from the fourth to the third side of the electrode pattern area, at the edge of the second bus group 31, breaks at the middle of the first bus group 22, and either breaks or thickens at the middle of the second bus group 32, continuing to extend continuously at the edge of the first bus group 21. It should be noted that the aforementioned continuously extending first collector grid line 11 is integrally printed between the fourth side and the edge of the second bus group 31, without any breaks, other material portions, or thickened portions. When the first collector grid line 11 breaks at the middle of the second bus group 32, the break can be connected by the second connecting portion 34. When the first collector grid line 11 is thickened at the middle of the second bus group 32, the thickened section can serve as one type of second connecting portion 34.

[0105] When the second collector grid line 12 in the middle region extends continuously from the third side to the second busbar group adjacent to the first busbar group 21 at the edge, and the first collector grid line 11 in the middle region extends continuously from the fourth side to the first busbar group adjacent to the second busbar group 31 at the edge, the polarities of the collector grid lines continuously arranged on the left and right sides are opposite, which can balance the collection efficiency of carriers with different polarities and reduce the probability of current imbalance on the battery cell.

[0106] In some embodiments, refer to Figure 5 and Figure 6 The edge second bus group 31 is the second bus group closest to the fourth side in the electrode pattern area. The second collector grid line 12 electrically connected to the second bus group extends continuously from the fourth side to the first bus group adjacent to the edge second bus group 31, and is interrupted or thickened at the first bus group, and is interrupted at the middle second bus group 32. The second collector grid line 12 electrically connected to the second bus group is also the second collector grid line 12 located in the middle region.

[0107] Specifically, the second collector grid line 12, electrically connected to the second bus group, extends continuously from the third to the fourth side of the electrode pattern area, at the edge of the first bus group 21, breaks off or is thickened at the middle of the first bus group 22, breaks off at the middle of the second bus group 32, and continues to extend continuously at the edge of the second bus group 31. In this embodiment, the second collector grid line 12 at the edge extends continuously until it breaks off at the first bus group adjacent to the edge of the second bus group 31, resulting in good current collection at the edge.

[0108] It should be noted that the aforementioned continuously extending second collector line 12 is integrally printed between the fourth side and the edge second bus group 31, without any discontinuities, other material portions, or thickened portions. When the second collector line 12 is broken at the middle first bus group 22, the break can be connected by the first connecting portion 24. When the second collector line 12 is thickened at the middle first bus group 22, the thickened section can serve as one type of the first connecting portion 24.

[0109] In some embodiments, the material of the first busbar 23 is the same as the material of the first connector 24, and the material of the first busbar 23 is different from the material of the first collector line 11 or the second collector line 12. The material of the second busbar 33 is the same as the material of the second connector 34, and the material of the second busbar 33 is different from the material of the first collector line 11 or the second collector line 12. The first busbar 23 and the first connector 24 are printed using the same paste, and the printing of the first busbar 23 and the first connector 24 can be completed simultaneously, which simplifies the printing process. Similarly, the second busbar 33 and the second connector 34 can also be printed simultaneously, which simplifies the printing process.

[0110] The materials of the first busbar 23 and the first connecting part 24 are different from the materials of the first current collector line 11 or the second current collector line 12. At the fusion point of the two different pastes, the line resistance increases. In this embodiment of the invention, the connecting part in the edge first busbar group 21 and the edge second busbar group 31 is eliminated, that is, the overlap between the connecting part and the current collector line in the edge first busbar group 21 and the edge second busbar group 31 is eliminated. This can reduce the overall fusion area of ​​the two different pastes on the solar cell, reduce the line resistance, thereby reducing resistance loss and improving current transmission efficiency.

[0111] In some embodiments, the material of the first connection portion 24 is the same as the material of the first collector line 11 or the second collector line 12, and the material of the first connection portion 24 is different from the material of the first bus portion 23. The material of the second connection portion 34 is the same as the material of the first collector line 11 or the second collector line 12, and the material of the second connection portion 34 is different from the material of the second bus portion 33.

[0112] In this embodiment, the connecting portion uses the same material as the current collector grid, which increases the contact area between the current collector grid and the insulating layer, as well as the area for forming an ohmic contact between the current collector grid and the cell surface, thereby improving the contact performance between the electrode and the cell. Furthermore, using the same material as the current collector grid avoids increased line resistance caused by the fusion of different pastes.

[0113] In some embodiments, when the material of the connecting portion is the same as that of the collector grid line, the connecting portion can be a thickened structure, the width of the connecting portion along the second direction is greater than the width of the collector grid line along the second direction, or the height of the connecting portion is greater than the height of the collector grid line.

[0114] In some embodiments, the battery body includes a silicon substrate and an N-type doped layer and a P-type doped layer disposed on the silicon substrate. The N-type and P-type doped layers extend along a first direction and are alternately spaced along a second direction. Both the N-type and P-type doped layers are disposed on the back side of the silicon substrate. Both the N-type and P-type doped layers are strip-shaped extending along the first direction, and are alternately spaced along the second direction. An isolation region is provided between the N-type and P-type doped layers. The silicon substrate can be an N-type silicon substrate or a P-type silicon substrate.

[0115] When the first collector gate line 11 is disposed on the N-type doped layer and the second collector gate line 12 is disposed on the P-type doped layer, the ratio of the width of the first bus 23 in the first bus group to the width of the corresponding N-type doped layer is greater than the ratio of the width of the second bus 33 in the second bus group to the width of the corresponding P-type doped layer; the ratio of the width of the first connection 24 in the first bus group to the width of the corresponding N-type doped layer is greater than the ratio of the width of the second connection 34 in the second bus group to the width of the corresponding P-type doped layer. The widths of the first bus 23, the second bus 33, the first connection 24, the second connection 34, the N-type doped layer, and the P-type doped layer all refer to their dimensions along the second direction.

[0116] In back-contact solar cells, when the silicon substrate is an N-type silicon substrate (meaning the silicon substrate is doped with N-type elements), setting the width of the P-type doped layer to be greater than the width of the N-type doped layer increases the junction area on the cell, improving carrier separation and transport capabilities. Furthermore, setting the ratio of the width of the busbar or connector to the width of the N-type doped layer to the width of the P-type doped layer is greater than the ratio to the width of the P-type doped layer. This helps maintain similar dimensions for the busbars or connectors connecting current collectors of different polarities, increasing the symmetry of the electrode pattern, reducing errors during printing, and improving printing accuracy.

[0117] In other embodiments, the ratio of the width of the bus or connector to the width of the N-type doped layer is set to be equal to the ratio of the width of the P-type doped layer. Since the width of the P-type doped layer is greater than the width of the N-type doped layer, this structural arrangement can increase the size of the connector or bus on the P-type doped layer, thereby increasing the accuracy of the overlap between the collector grid line and the bus or connector during the printing of the collector grid line, bus or connector on the P-type doped layer.

[0118] In some embodiments, refer to Figure 10 The size of the first busbar 23 is larger than the size of the first connector 24. (Refer to...) Figure 7 The size of the second busbar 33 is larger than the size of the second connector 34.

[0119] The dimensions of the first busbar 23 can be its length, width, and / or its projected area on the back of the battery cell, and the dimensions of the first connector 24 can be its length, width, and / or its projected area on the back of the battery cell. Preferably, the length of the first busbar 23 is greater than the length of the first connector 24, and the width of the first busbar 23 is greater than the width of the first connector 24.

[0120] The dimensions of the second busbar 33 can be its length, width, and / or its projected area on the back of the battery cell, and the dimensions of the second connecting portion 34 can be its length, width, and / or its projected area on the back of the battery cell. Preferably, the length of the second busbar 33 is greater than the length of the second connecting portion 34, and the width of the second busbar 33 is greater than the width of the second connecting portion 34.

[0121] On the one hand, if the lengths of the first connecting portion 24 and the second connecting portion 34 along the first direction are too large, it will lead to waste of slurry; on the other hand, if the lengths of the first connecting portion 24 and the second connecting portion 34 along the first direction are too small, it will lead to increased transmission loss. In view of the above two aspects, in this technical solution, the lengths of the first connecting portion 24 and the second connecting portion 34 along the first direction are set within a reasonable range of 300μm-500μm, so as to save slurry while ensuring a reasonable contact area between the interconnect and the first connecting portion 24 and the second connecting portion 34, thereby reducing transmission loss. For example, the lengths of the first connecting portion 24 and the second connecting portion 34 along the first direction can be 300μm, 320μm, 350μm, 380μm, 400μm, 420μm, 450μm, 480μm, or 500μm, etc.

[0122] On the one hand, if the widths of the first connecting portion 24 and the second connecting portion 34 along the second direction are too large, they may extend into areas not covered by the insulation layer, causing leakage current when they come into contact with the current collector or current collection grid line of opposite polarity, and resulting in wasted paste. On the other hand, if the widths of the first connecting portion 24 and the second connecting portion 34 along the second direction are too small, it will easily increase the difficulty of aligning the current collection grid line with the current collector, leading to problems such as incomplete printing or broken grid lines during the printing process, and will also increase the difficulty of aligning the insulation layer during printing. In view of the above two aspects, in this technical solution, the width range of the first connecting portion 24 and the second connecting portion 34 along the second direction is set within a reasonable range of 20μm-120μm to reduce the risk of leakage current, save paste, reduce manufacturing costs, and reduce transmission loss. For example, the width of the first connecting portion 24 and the second connecting portion 34 along the second direction is 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm or 120μm, etc.

[0123] The projected area of ​​the first connecting part 24 and the second connecting part 34 on the back of the battery cell is 6000 μm. 2 8000μm 2 1000μm 2 1500μm 2 20000μm 2 25000μm 2 30000μm 2 35000μm 2 40000μm 2 45000μm 2 50000μm 2 55000μm 2 Or 60000μm 2 The technical effect of setting the range of the projected area of ​​the first connecting part 24 and the second connecting part 34 on the back of the battery cell can be referred to the technical effect of the length or width of the first connecting part 24 and the second connecting part 34, and will not be described again here.

[0124] In some embodiments, the lengths of the first busbar 23 and the second busbar 33 along the first direction are set within a reasonable range of 300μm-500μm to save slurry while ensuring a reasonable contact area between the interconnect and the first busbar 23 and the second busbar 33, thereby reducing contact resistance and transmission loss. For example, the lengths of the first busbar 23 and the second busbar 33 along the first direction can be 300μm, 320μm, 350μm, 380μm, 400μm, 420μm, 450μm, 480μm, or 500μm, etc.

[0125] In some embodiments, the widths of the first busbar 23 and the second busbar 33 along the second direction are set within a reasonable range of 20μm-120μm. For example, the widths of the first busbar 23 and the second busbar 33 along the second direction are 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, or 120μm, etc.

[0126] In some embodiments, the projected area of ​​the first busbar 23 and the second busbar 33 on the back side of the battery cell is set to 6000 μm. 2 ~60000μm 2 Within a reasonable range, for example, the projected area of ​​the first busbar 23 and the second busbar 33 on the back side of the solar cell is 6000 μm. 2 8000μm 2 10000μm 2 15000μm 2 20000μm 2 25000μm 2 30000μm 2 35000μm 2 40000μm 2 45000μm 2 50000μm 2 55000μm 2 Or 60000μm 2 .

[0127] The technical effects of the width range and projected area range of the first shunt 23 and the second shunt 33 can be referred to the technical effects of the length range of the first shunt 23 and the second shunt 33, and will not be described again here.

[0128] The first current collector line 11 is electrically connected to the interconnect through a larger first busbar 23, and the second current collector line 12 is electrically connected to the interconnect through a larger second busbar 33. Since the width of the busbar along the second direction is greater than the width of the current collector line, the contact area between the busbar and the surface of the cell and the welding contact area with the interconnect are increased, which can reduce the risk of weld breakage and improve the adhesion between the cell and the interconnect, thereby improving the welding reliability.

[0129] Furthermore, the first connecting part 24 of the first busbar group is insulated from the interconnecting member, and the second connecting part 34 of the second busbar group is insulated from the interconnecting member. Since the width of the connecting part is greater than the width of the current collector grid line, it can increase the contact area between the current collector grid line and the back contact battery surface, and provide a larger area for subsequent printing of the insulating layer, thereby enhancing the bonding force between the insulating layer and the grid line on the battery cell. By simultaneously increasing the bonding force between different structures, the bonding force between the interconnecting member and the battery cell is improved, reducing the possibility of the interconnecting member falling off the battery cell.

[0130] Furthermore, the dimensions of the first connecting portion 24 and the second connecting portion 34 are smaller than those of the first busbar 23 and the second busbar 33, respectively. This can prevent the first connecting portion 24 and the second connecting portion 34 from extending into areas not covered by the insulation layer, which could lead to leakage between the first connecting portion 24 or the second connecting portion 34 and the busbar or collector wire with opposite polarity. At the same time, it can save more paste when printing the first connecting portion 24 and the second connecting portion 34, thereby reducing manufacturing costs.

[0131] In some embodiments, refer to Figure 7 The edge region is provided with multiple welding parts, including a first welding part 40. Along the second direction, a first welding part 40 is provided between an intermediate first busbar group 22 and a first side, and a first welding part 40 is provided between an intermediate first busbar group 22 and a second side. The first welding part 40 includes a first rectangular part 41 and a first end line 42. The first end line 42 extends along the second direction, and the dimension of the first rectangular part 41 along the second direction is larger than the dimension of the first busbar 23 along the second direction.

[0132] The boundary line between the middle region and the edge region is located between the first welding portion 40 and the middle first busbar group 22. This boundary line can be seen as the line indicated by the dashed line S in the diagram. The dimension of the first rectangular portion 41 along the second direction is specifically the length of the first rectangular portion 41, and the dimension of the first busbar 23 along the second direction is specifically the width of the first busbar 23. In this embodiment, the interconnect only needs to extend to the end of the first welding portion 40 and be electrically connected to it. That is, the interconnect only needs to extend to the position of the first rectangular portion 41, without needing to extend to the edge of the battery cell. This reduces stress concentration at the edge of the battery cell during lamination and improves product yield.

[0133] In some embodiments, refer to Figure 7 The plurality of welding portions include a second welding portion 50. Along the second direction, a second welding portion 50 is provided between an intermediate second busbar group 32 and a first side, and a second welding portion 50 is provided between an intermediate second busbar group 32 and a second side. The second welding portion 50 includes a second rectangular portion 51 and a second end line 52. The second end line 52 extends along the second direction, and the dimension of the second rectangular portion 51 along the second direction is greater than the dimension of the second busbar 33 along the second direction.

[0134] The dimension of the second rectangular portion 51 along the second direction is specifically the length of the second rectangular portion 51, and the dimension of the second busbar portion 33 along the second direction is specifically the width of the second busbar portion 33. In this embodiment, the interconnect only needs to extend to the end of the second welding portion 50 and be electrically connected to the second welding portion 50. The interconnect only needs to extend to the position of the second rectangular portion 51, and does not need to extend to the edge of the battery cell. This can reduce the stress concentration at the edge of the battery cell during the lamination process and improve the product yield.

[0135] In some embodiments, refer to Figure 7 and Figure 8 The first welding portion 40 includes a first rectangular portion 41 and a first end line 42. The first end line 42 is electrically connected to the first collector grid line 11 in the edge region through the third connecting portion 61. The first collector grid line 11 in the edge region is provided with a third discontinuity corresponding to the third connecting portion 61. Along the first direction, the length of the third discontinuity is greater than the width of the first end line 42 and less than the length of the third connecting portion 61.

[0136] The first welding portion 40 is used for welding with interconnecting components. The length of the first rectangular portion 41 along the second direction is greater than the width of the first busbar 23 along the second direction, and the length of the first end line 42 along the second direction is greater than the length of the first rectangular portion 41 along the second direction. The length of the third discontinuity section can be referenced. Figure 8 The width of the first end line 42 shown in the figure refers to the width of the first end line 42 corresponding to the position of the third discontinuity zone.

[0137] Along the first direction, the second collector grid line 12 in the edge region forms a fourth discontinuity at the first end line 42 to prevent leakage. Along the first direction, the length of the fourth discontinuity can be greater than the length of the third connection portion 61. The third connection portion 61 and the first welding portion 40 can be printed integrally or separately.

[0138] In some embodiments, along the first direction, the second collector grid line 12 in the edge region forms a fourth discontinuity at the first end line 42. The length of the fourth discontinuity is greater than the length of the third discontinuity, which effectively prevents leakage and reduces the risk of leakage. Preferably, the length of the fourth discontinuity is greater than the length of the third connection portion 61.

[0139] In this embodiment, the length of the third discontinuity zone is greater than the width of the first end line 42. On the one hand, this saves slurry; on the other hand, when the material of the first current collector line 11 is different from the materials of the third connection portion 61 and the first end line 42, the fusion length of the different slurries can be reduced, thereby reducing the line resistance. Furthermore, for the first weld portion 40 where current and voltage test points are provided, this helps ensure the stability of the test.

[0140] In some embodiments, refer to Figure 7 and Figure 9 The second welding part 50 includes a second rectangular part 51 and a second end line 52. The second end line 52 is electrically connected to the second collector grid line 12 in the edge region through the fourth connecting part 62. The second collector grid line 12 in the edge region is provided with a fifth discontinuity corresponding to the fourth connecting part 62. Along the first direction, the length of the fifth discontinuity is greater than the width of the second end line 52 and less than the length of the fourth connecting part 62.

[0141] The second welding portion 50 is used for welding with the interconnecting component. The length of the second rectangular portion 51 along the second direction is greater than the width of the second busbar portion 33 along the second direction, and the length of the second end line 52 along the second direction is greater than the length of the second rectangular portion 51 along the second direction. The width of the second end line 52 refers to the width of the second end line 52 corresponding to the position of the fifth discontinuity zone.

[0142] Along the first direction, the first collector grid line 11 in the edge region forms a sixth discontinuity at the second end line 52 to prevent leakage. Along the first direction, the length of the sixth discontinuity can be greater than the length of the fourth connection portion 62. The fourth connection portion 62 and the second welding portion 50 can be printed integrally or separately.

[0143] In this embodiment, the length of the fifth discontinuity zone is greater than the width of the second end line 52. On the one hand, this saves slurry; on the other hand, when the material of the second current collector line 12 is different from the materials of the fourth connection portion 62 and the second end line 52, the fusion length of the different slurries can be reduced, thereby reducing the line resistance. Furthermore, the second welding portion 50, which has current and voltage test points, is designed to ensure the stability of the tests.

[0144] In some embodiments, along the first direction, the first collector grid line 11 in the edge region forms a sixth interruption zone at the second end line 52. The length of the sixth interruption zone is greater than the length of the fifth interruption zone, which has a good effect in preventing leakage and can effectively reduce the risk of leakage. The length of the sixth interruption zone is preferably greater than the length of the fourth connection portion 62.

[0145] In some embodiments, refer to Figure 9 The collector grid line closest to the edge in the electrode pattern area is the first collector grid line 11. Multiple seventh discontinuity zones are provided on the collector grid line closest to the edge, and an edge connection portion 70 is provided at the seventh discontinuity zone. The length of the edge connection portion 70 is equal to the length of the adjacent fourth connection portion 62, which can ensure printing stability and reduce the amount of paste used in the connection portion.

[0146] In some embodiments, along the first direction, the first collector grid line 11 in the intermediate region is provided with a first discontinuity region, and the second collector grid line 12 in the intermediate region is provided with a second discontinuity region; the length of the first discontinuity region is greater than 0 mm and less than or equal to 0.4 mm, and the length of the second discontinuity region is greater than 0 mm and less than or equal to 0.4 mm.

[0147] In this configuration, the first collector wire 11 has a first discontinuity section corresponding to the positions of the first busbar 23 and the second connection 34. The lengths of the first discontinuity section corresponding to the first busbar 23 and the first discontinuity section corresponding to the second connection 34 may be equal or unequal. Similarly, the second collector wire 12 has a second discontinuity section corresponding to the positions of the second busbar 33 and the first connection 24. The lengths of the second discontinuity section corresponding to the second busbar 33 and the second discontinuity section corresponding to the first connection 24 may be equal or unequal.

[0148] The length of the first discontinuity can be referenced. Figure 10 The length of the second discontinuity region, L1, shown in the figure, can be referenced. Figure 10L2 is shown in the diagram. The lengths of the first discontinuity and the second discontinuity can be equal or unequal. The length of the first discontinuity can be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, etc. The length of the second discontinuity can be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, etc.

[0149] If the lengths of the first and second discontinuity zones are too short, the fusion length of different slurries will be too long, leading to an increase in line resistance. If the lengths of the first and second discontinuity zones are too long, the probability of offset printing and incomplete printing during the connection process between the connector or busbar and the collector grid line will increase, reducing production yield. In this embodiment, when the lengths of the first and second discontinuity zones are within the above-mentioned range, it is possible to avoid an increase in line resistance while reducing the probability of offset printing and incomplete printing during the connection process between the connector or busbar and the collector grid line.

[0150] Reference Figure 2 Along the first direction, on the same first collector grid line 11, two adjacent first discontinuity sections correspond to the first busbar 23 and the second connection section 34, respectively. In the same intermediate first busbar group 22, the length of the first discontinuity section corresponding to the first busbar 23 is greater than or equal to the length of the second discontinuity section corresponding to the first connection section 24.

[0151] On the same second collector line 12, two adjacent second discontinuity sections correspond to the second busbar 33 and the first connection section 24, respectively. In the same intermediate second busbar group 32, the length of the second discontinuity section corresponding to the second busbar 33 is greater than or equal to the length of the first discontinuity section corresponding to the second connection section 34.

[0152] In some embodiments, in the same intermediate first busbar group 22, the length of the first discontinuity corresponding to the first busbar 23 is greater than the length of the second discontinuity corresponding to the first connection 24. In the same intermediate second busbar group 32, the length of the second discontinuity corresponding to the second busbar 33 is greater than or equal to the length of the first discontinuity corresponding to the second connection 34. Correspondingly, on the same first collector grid line 11, the lengths of two adjacent first discontinuities are unequal, and on the same second collector grid line 12, the lengths of two adjacent second discontinuities are unequal.

[0153] The busbar is used to connect with the interconnect. The length of the discontinuity zone corresponding to the busbar is set relatively large, which can shorten the length of the height change area on the busbar and ensure the connection performance between the busbar and the interconnect. The connector does not need to have a long discontinuity zone, so as to reduce the difficulty of overlapping the collector wire and the connector.

[0154] In some embodiments, along a first direction, in the first bus group, the overlap ratio of the first collector line 11 and the first bus 23 is greater than or equal to the overlap ratio of the second collector line 12 and the first connection 24. In some other embodiments, the overlap ratio of the first collector line 11 and the first bus 23 is greater than the overlap ratio of the second collector line 12 and the first connection 24.

[0155] The overlap ratio of the first collector line 11 and the first bus 23 can refer to the ratio of the overlap length of the first collector line 11 and the first bus 23 to the length of the first bus 23 along the first direction. Alternatively, the overlap ratio can refer to the ratio of the overlap area of ​​the first collector line 11 and the first bus 23 to the area of ​​the first bus 23. Furthermore, the overlap ratio can also refer to the ratio of the product of the overlap length and overlap width of the first collector line 11 and the first bus 23 to the product of the length and width of the first bus 23.

[0156] The overlap ratio of the second collector line 12 and the first connection portion 24 can be defined as the ratio of the overlap length of the second collector line 12 and the first connection portion 24 to the length of the first connection portion 24 along the first direction. Alternatively, the overlap ratio can be defined as the ratio of the overlap width of the second collector line 12 and the first connection portion 24 to the width of the edge of the first connection portion 24. Furthermore, the overlap ratio can also be defined as the ratio of the product of the overlap length and overlap width of the second collector line 12 and the first connection portion 24 to the area of ​​the first connection portion 24.

[0157] The first busbar 23 needs to be soldered to the interconnect. If the overlap rate between the first collector grid line 11 and the first busbar 23 is too small, the probability of offset printing and incomplete printing during the connection process increases, making it difficult to guarantee the reliability of the current collected by the collector grid line to be transmitted to the interconnect. In this embodiment, the overlap rate between the first collector grid line 11 and the first busbar 23 is greater than or equal to the overlap rate between the second collector grid line 12 and the first connection portion 24, which can guarantee the reliability of the current collected by the first collector grid line 11 to be transmitted to the interconnect. In some embodiments, along the first direction, the overlap rate between the second collector grid line 12 and the first connection portion 24 is 30%-65%.

[0158] The overlap rate between the second collector line 12 and the first connection portion 24 can be 30%, 35%, 40%, 45%, 50%, 60%, 65%, etc. If the overlap rate between the second collector line 12 and the first connection portion 24 is too large, the fusion length of different pastes will be large, which will lead to an increase in line resistance. If the overlap rate between the second collector line 12 and the first connection portion 24 is too small, the probability of offset printing and incomplete printing during the connection process between the connection portion and the collector line will increase, which will reduce the production yield. In this embodiment, when the overlap rate between the second collector line 12 and the first connection portion 24 is within the above range, it can avoid an increase in line resistance while reducing the probability of offset printing and incomplete printing during the connection process between the connection portion and the collector line.

[0159] In some embodiments, the overlap rate between the first collector grid line 11 and the first bus 23 along the first direction is 50%-80%.

[0160] The overlap ratio between the first collector line 11 and the first bus 23 can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc. If the overlap ratio between the first collector line 11 and the first bus 23 is too large, the fusion length of different pastes will be large, which will lead to an increase in line resistance. If the overlap ratio between the first collector line 11 and the first bus 23 is too small, it will be difficult to ensure the reliability of the current collected by the collector line being transmitted to the interconnect. In this embodiment, when the overlap ratio between the first collector line 11 and the first bus 23 is within the above range, it can avoid the increase in line resistance while ensuring the reliability of the current collected by the first collector line 11 being transmitted to the interconnect.

[0161] In some embodiments, along the first direction, the overlap rate between the second collector line 12 and the second bus 33 is greater than or equal to the overlap rate between the first collector line 11 and the second connection portion 34. Along the first direction, the overlap rate between the second collector line 12 and the second bus 33 is 30%-65%. Along the first direction, the overlap rate between the first collector line 11 and the second connection portion 34 is 50%-80%. The overlap rate between the second collector line 12 and the second bus 33 can be referred to the description of the overlap rate between the first collector line 11 and the first bus 23 described above, and the overlap rate between the first collector line 11 and the second connection portion 34 can be referred to the description of the overlap rate between the second collector line 12 and the first connection portion 24 described above, and will not be repeated here.

[0162] In some embodiments, the first busbar 23 is rectangular or elliptical in shape; the first connecting portion 24 is I-shaped, rectangular, elliptical, trapezoidal, or spindle-shaped. The second busbar 33 is rectangular or elliptical in shape; the second connecting portion 34 is I-shaped, rectangular, elliptical, trapezoidal, or spindle-shaped.

[0163] The elliptical busbar ensures a good overlap while reducing the area of ​​light shading. The rectangular busbar ensures a larger contact area when the busbar overlaps with the collector wire or is connected to interconnects, reducing alignment difficulties in the manufacturing process.

[0164] As an example Figure 11 The first connecting portion 24 shown is H-shaped. When the first connecting portion 24 is H-shaped, the width at both ends of the first connecting portion 24 is greater than the width in the middle. This reduces the difficulty of aligning the second collector grid line 12 with the two ends of the first connecting portion 24, and avoids excessively increasing the area of ​​the first connecting portion 24, thereby avoiding excessively increasing the amount of slurry consumed.

[0165] In some embodiments, after printing and sintering, the first connecting portion 24 is as follows: Figure 12 As shown in the figure, the corner areas of the first connecting portion 24 exhibit a rounded and full shape. This is due to the leveling characteristics of the ink during the printing process.

[0166] This invention also provides a photovoltaic module, which includes multiple battery strings, each battery string including multiple back contact batteries as described above and multiple interconnecting elements. The interconnecting elements connect two adjacent back contact batteries in series or in parallel. The interconnecting elements are electrically connected to the first busbar 23 and the second busbar 33 through a conductive layer, and the interconnecting elements are insulated from the first connection portion and the second connection portion through an insulating layer.

[0167] The conductive layer may include several conductive adhesives, solder pastes, etc., and the insulating layer may include several insulating adhesives. The interconnecting components may be flat solder ribbons, round wire solder ribbons, film-coated solder ribbons, solder ribbons with elliptical or other polygonal cross-sections, etc.

[0168] The interconnect connects two adjacent back contact batteries, one of which is a first back contact battery and the other is a second back contact battery. Along a first direction, the first busbar group of the first back contact battery is aligned with the second busbar group of the second back contact battery, or vice versa. The interconnect is electrically connected to the first busbar 23 in the first back contact battery and insulated from the first connecting portion 24. The interconnect is also electrically connected to the second busbar 33 in the second back contact battery and insulated from the second connecting portion 34. Alternatively, the interconnect is electrically connected to the second busbar 33 in the first back contact battery and insulated from the second connecting portion 34, and the interconnect is also electrically connected to the first busbar 23 in the second back contact battery and insulated from the first connecting portion 24.

[0169] In some embodiments, a photovoltaic module includes a backsheet, a back film, multiple cell strings, a front film, and a front glass, stacked sequentially. The film can be made of EVA (ethylene-vinyl acetate copolymer), POE (polyolefin elastomer), or EPE (expanded polyethylene), etc. The front glass can be tempered glass, semi-tempered glass, or patterned glass. The backsheet can be a white backsheet or glass.

[0170] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0171] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other modifications under the guidance of the present invention without departing from the spirit and scope of the present invention, and all of these modifications are within the protection scope of the present invention.

Claims

1. A back-contact battery, characterized in that, include: The battery body includes the back side and the second surface of the battery cells disposed opposite to each other; At least one electrode pattern area is disposed on the back side of the solar cell; Multiple first collector grid lines and multiple second collector grid lines are disposed within the electrode pattern area, and extend along a first direction and are alternately distributed along a second direction. The first direction and the second direction intersect, and the first collector grid lines and the second collector grid lines have different polarities. Multiple first busbar groups and multiple second busbar groups are disposed at least in the middle portion of the electrode pattern area and are alternately distributed along the first direction; The first busbar group includes a plurality of first busbars and a plurality of first connecting parts that are alternately distributed along the second direction. The first busbars are electrically connected to the first collector grid lines, and the first connecting parts are electrically connected to the second collector grid lines. The second busbar group includes a plurality of second busbars and a plurality of second connecting parts that are alternately distributed along the second direction. The second busbars are electrically connected to the second collector grid lines, and the second connecting parts are electrically connected to the first collector grid lines. The plurality of first busbar groups include an intermediate first busbar group and an edge first busbar group, wherein the number of first connecting parts in the edge first busbar group is less than the number of first connecting parts in the intermediate first busbar group.

2. The back contact battery according to claim 1, characterized in that, The intermediate first confluence group includes a plurality of first confluences and a plurality of first connecting parts that are alternately distributed along the second direction, and the edge first confluence group is composed of first confluences arranged along the second direction.

3. The back contact battery according to claim 2, characterized in that, The electrode pattern area has a first side and a second side arranged opposite to each other along the second direction, and there is no discontinuity between the first collector grid line and the first side of the edge first busbar group; And / or, between the first collector grid line and the second side, there is no discontinuity between the first collector grid line and the second collector grid line.

4. The back contact battery according to claim 2, characterized in that, The electrode pattern area has a third side and a fourth side that are arranged opposite to each other along the first direction; The first busbar group at the edge is the first busbar group closest to the third side in the electrode pattern area, and the second collector grid line electrically connected to the second busbar group extends continuously from the third side to the second busbar group adjacent to the first busbar group at the edge.

5. The back contact battery according to claim 2 or 4, characterized in that, The electrode pattern area has a third side and a fourth side that are arranged opposite to each other along the first direction; The first busbar group at the edge is the first busbar group closest to the third side in the electrode pattern area, and the first collector grid line electrically connected to the first busbar group extends continuously from the third side to the second busbar group adjacent to the first busbar group at the edge.

6. The back contact battery according to any one of claims 1 to 4, characterized in that, The plurality of second busbar groups include a middle second busbar group and an edge second busbar group. The electrode pattern area has a third side and a fourth side disposed opposite to each other along the first direction. The edge first busbar group is the first busbar group in the electrode pattern area that is closest to the third side. The edge second busbar group is the second busbar group in the electrode pattern area that is closest to the fourth side. The number of second connecting portions in the edge second busbar group is less than the number of second connecting portions in the middle second busbar group and / or the number of first connecting portions in the middle first busbar group.

7. The back contact battery according to any one of claims 1 to 4, characterized in that, The size of the first busbar is larger than the size of the first connector.

8. The back contact battery according to any one of claims 1 to 4, characterized in that, The battery body includes an N-type doped layer and a P-type doped layer, the N-type doped layer and the P-type doped layer extending along the first direction and being alternately distributed along the second direction; When the first collector gate line is disposed on the N-type doped layer and the second collector gate line is disposed on the P-type doped layer, the ratio of the width of the first bus in the first bus group to the width of the N-type doped layer at the corresponding position is greater than the ratio of the width of the second bus in the second bus group to the width of the P-type doped layer at the corresponding position. And / or, the ratio of the width of the first connector in the first busbar group to the width of the N-type doped layer at the corresponding position is greater than the ratio of the width of the second connector in the second busbar group to the width of the P-type doped layer at the corresponding position.

9. The back contact battery according to any one of claims 1 to 4, characterized in that, The electrode pattern area has a first side and a second side disposed opposite to each other along a second direction, and the electrode pattern area includes a middle region and an edge region located between the middle region and the first side or the second side; The edge region is provided with a plurality of welding parts, the plurality of welding parts including a first welding part. Along the second direction, a first welding part is provided between one of the intermediate first confluence groups and the first side, and a first welding part is provided between one of the intermediate first confluence groups and the second side. The first welding part includes a first rectangular part and a first end line.

10. The back contact battery according to claim 9, characterized in that, The dimension of the first rectangular portion along the second direction is greater than the dimension of the first confluence portion along the second direction.

11. The back contact battery according to claim 9, characterized in that, The first end line extends along the second direction, and the first end line is electrically connected to the first collector grid line in the edge region through the third connecting portion; The first collector grid line in the edge region is provided with a third discontinuity corresponding to the third connection portion. Along the first direction, the length of the third discontinuity is greater than the width of the first end line and less than the length of the third connection portion.

12. The back contact battery according to claim 11, characterized in that, Along the first direction, the second collector grid line in the edge region forms a fourth discontinuity at the first end line, and the length of the fourth discontinuity is greater than the length of the third discontinuity.

13. The back contact battery according to any one of claims 1 to 4, characterized in that, The electrode pattern area has a first side and a second side disposed opposite to each other along a second direction, and the electrode pattern area includes a middle region and an edge region located between the middle region and the first side or the second side; Along the first direction, the first collector grid line in the intermediate region is provided with a first discontinuity, and the second collector grid line in the intermediate region is provided with a second discontinuity.

14. The back contact battery according to claim 13, characterized in that, The length of the first discontinuity is greater than 0 mm and less than or equal to 0.4 mm, and / or the length of the second discontinuity is greater than 0 mm and less than or equal to 0.4 mm.

15. The back contact battery according to claim 13, characterized in that, Along the first direction, on the same first collector grid line, two adjacent first discontinuity regions correspond to the first busbar and the second connection, respectively; In the same intermediate first busbar group, the length of the first discontinuity zone corresponding to the first busbar is greater than or equal to the length of the second discontinuity zone corresponding to the first connecting part.

16. The back contact battery according to any one of claims 1 to 4, characterized in that, Along the first direction, in the first busbar group, the overlap rate of the first collector grid line with the first busbar is greater than or equal to the overlap rate of the second collector grid line with the first connection.

17. The back contact battery according to claim 16, characterized in that, Along the first direction, the overlap rate between the second collector grid line and the first connection portion is 30%-65%; And / or, along the first direction, the overlap rate between the first collector grid line and the first bus is 50%-80%.

18. The back contact battery according to any one of claims 1 to 4, characterized in that, The material of the first busbar is the same as the material of the first connector, and the material of the first busbar is different from the material of the first collector grid line or the second collector grid line.

19. The back contact battery according to any one of claims 1 to 4, characterized in that, The first busbar is rectangular or elliptical in shape; The shape of the first connecting part is I-shaped, rectangular, elliptical, trapezoidal or spindle-shaped.

20. A photovoltaic module, characterized in that, The battery string includes multiple battery strings, each battery string including multiple back contact batteries as described in any one of claims 1 to 19 and multiple interconnecting elements, the interconnecting elements connecting two adjacent back contact batteries in series or in parallel; The interconnecting component is electrically connected to the first busbar and the second busbar through a conductive layer, and the interconnecting component is insulated from the first connection and the second connection through an insulating layer.

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