A back contact cell, cell string, cell assembly and photovoltaic system

Abstract

The utility model is suitable for photovoltaic cell technical field provides a kind of back contact cell, battery string, battery module and photovoltaic system, back contact cell includes: silicon base;First fine grid and second fine grid;Back has first soldering area and second soldering area;First pre-adhesive;First solder joint being located in first soldering area and being arranged on first fine grid, first solder joint includes first offset solder joint, the offset direction of at least one first offset solder joint on same first fine grid is opposite with the offset direction of at least one first offset solder joint remaining;Second pre-adhesive;Second solder joint being located in second soldering area and being arranged on second fine grid, second solder joint includes second offset solder joint, the offset direction of at least one second offset solder joint on same second fine grid is opposite with the offset direction of at least one second offset solder joint remaining;The back contact cell of the utility model can reduce the risk that solder strip and part fine grid cannot electrically contact, ensure that battery module good power generation power.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic cell technology, and in particular to a back contact battery, a battery string, a battery module and a photovoltaic system. Background Technology

[0002] Solar cells, also known as photovoltaic cells, are devices that directly convert light energy into direct current (DC) using the photovoltaic effect. Back-contact solar cells, with both positive and negative electrodes located on the back of the cell, completely avoid shading by metal grid lines on the front surface, eliminating optical losses caused by this and significantly improving conversion efficiency compared to bifacial solar cells. Furthermore, gridless back-contact cells eliminate the need for a main grid, reducing paste usage and further lowering production costs.

[0003] In related technologies, gridless back-contact solar cells mainly employ a lamination and welding method to interconnect solar cells and form solar modules. This involves printing solder joints on the fine grids of the welding area of ​​the gridless back-contact solar cell, applying pre-adhesive at corresponding positions in the welding area, then laying solder ribbons on the welding area and pre-fixing them with the pre-adhesive. During lamination, the solder ribbons are welded to the solder joints on the fine grids of the gridless back-contact solar cell. Because some solder joints on the fine grids of the gridless back-contact solar cell need to avoid the pre-adhesive, the solder joints corresponding to the pre-adhesive positions on the fine grids are typically offset from the pre-adhesive placement. However, the offset solder joints in each welding area are usually offset in the same direction. However, during the welding process of gridless back contact cells and solder strips, since each solder strip is usually placed synchronously on the corresponding welding area of ​​the gridless back contact cell, the solder strip is very likely to be offset from the corresponding welding area. This can easily cause the offset solder joints on each solder strip and the fine grid to be misaligned at the same time. As a result, it is very easy for the solder strip to fail to make electrical contact with some of the fine grids on the gridless back contact cell, so that some of the charge carriers collected by the fine grid cannot be gathered on the solder strip, thus affecting the power generation efficiency of the battery module. Utility Model Content

[0004] This invention provides a back contact battery, which aims to solve the problem in the prior art where the solder ribbon can easily fail to make electrical contact with some of the fine grids on the back contact battery, resulting in a reduction in the power generation efficiency of the battery module.

[0005] This invention is implemented by providing a back contact battery, comprising:

[0006] Silicon substrate;

[0007] A plurality of first fine gates and a plurality of second fine gates are disposed on the back side of the silicon substrate, the first fine gates and the second fine gates being arranged alternately and spaced apart along a first direction, and both the first fine gates and the second fine gates extending along a second direction, the second direction intersecting the first direction; the back side has a first welding area and a second welding area arranged alternately and spaced apart along the second direction;

[0008] A first pre-adhesive is provided on at least one side of the first welding area, and the first pre-adhesive extends at least partially into the first welding area;

[0009] A first solder joint is provided on the first fine grid and located in the first welding area. The first solder joint includes a first offset solder joint that is offset away from the central axis of the first welding area from the direction corresponding to the first pre-adhesive. The offset direction of at least one first offset solder joint on the same first fine grid is opposite to the offset direction of the other at least one first offset solder joint.

[0010] A second pre-adhesive is disposed on at least one side of the second welding area, the second pre-adhesive at least partially extending into the second welding area; and

[0011] A second solder joint is provided on the second fine grid and located in the second welding area. The second solder joint includes a second offset solder joint that is offset away from the central axis of the second welding area in the direction corresponding to the second pre-adhesive. The offset direction of at least one second offset solder joint on the same second fine grid is opposite to the offset direction of the other at least one second offset solder joint.

[0012] Preferably, the offset directions of two adjacent first offset solder points on the same first fine grid are opposite.

[0013] Preferably, the offset directions of two adjacent second offset solder points on the same second fine gate are opposite.

[0014] Preferably, the first solder joint further includes a first central solder joint located on the central axis of the first welding area, and the first central solder joint is provided on a portion of the first fine grid, and the first offset solder joint is offset relative to the first central solder joint in the second direction.

[0015] Preferably, the first welding area is provided with multiple sets of first offset solder points arranged sequentially along the first direction, and each set of first offset solder points includes a plurality of first offset solder points arranged at intervals along the first direction.

[0016] Preferably, within each first welding zone, at least two sets of the first offset weld points have opposite offset directions.

[0017] Preferably, the first welding area is provided with a plurality of first central weld points arranged sequentially along the first direction, each group of first central weld points including at least one first central weld point, and the plurality of groups of first central weld points and the plurality of groups of first offset weld points are alternately arranged along the first direction.

[0018] Preferably, the line connecting the center points of all the first weld points in each first welding area forms a first line segment. The first line segment includes a first straight line segment formed by sequentially connecting the center points of each group of first central weld points and a first curved segment formed by sequentially connecting the center points of each group of first offset weld points. The first curved segment is curved relative to the first straight line segment, and the two first curved segments of two adjacent first welding areas located at the same position in the first direction have opposite curvature directions.

[0019] Preferably, the second solder joint includes a second central solder joint located on the central axis of the second welding area, a portion of the second fine grid is provided with the second central solder joint, and the second offset solder joint is offset relative to the second central solder joint in the second direction.

[0020] Preferably, each second welding zone is provided with a plurality of sets of second offset solder points arranged sequentially along the first direction, and each set of second offset solder points includes a plurality of second offset solder points arranged at intervals along the first direction.

[0021] Preferably, at least two sets of the second offset weld points in each second welding zone have opposite offset directions.

[0022] Preferably, the second welding area is provided with a plurality of sets of second center weld points arranged sequentially along the first direction, each set of second center weld points including at least one second center weld point, and the plurality of sets of second center weld points and the plurality of sets of second offset weld points are alternately arranged along the first direction.

[0023] Preferably, the line connecting the center points of all the second weld points in each second welding area forms a second line segment. The second line segment includes a second straight line segment formed by sequentially connecting the center points of each group of second center weld points and a second curved segment formed by sequentially connecting the center points of each group of second offset weld points. The second curved segment is curved relative to the second straight line segment, and the two second curved segments located at the same position in the first direction in two adjacent second welding areas have opposite curvature directions.

[0024] Preferably, all the first solder joints in two adjacent first welding areas are arranged in a mirror-symmetric manner, and / or, all the second solder joints in two adjacent second welding areas are arranged in a mirror-symmetric manner.

[0025] Preferably, the first solder joint further includes:

[0026] A plurality of first edge solder joints are disposed on the first fine gate near the edge of the silicon substrate, and the plurality of first edge solder joints are arranged sequentially at intervals along the second direction.

[0027] Preferably, the second solder joint further includes:

[0028] A plurality of second edge solder joints are disposed on the second fine gate near the edge of the silicon substrate, and the plurality of second edge solder joints are arranged sequentially at intervals along the second direction.

[0029] Preferably, two adjacent first pre-adhesives located at the same position in the first direction are offset in opposite directions relative to the corresponding first welding area; and / or, two adjacent second pre-adhesives located at the same position in the first direction are offset in opposite directions relative to the corresponding second welding area.

[0030] Preferably, each of the first welding areas is provided with multiple sets of the first pre-adhesive arranged sequentially along the first direction, and the multiple sets of the first pre-adhesive are alternately arranged on both sides of the first welding area.

[0031] Preferably, each second welding area is provided with multiple sets of second pre-adhesive arranged sequentially along the first direction, and the multiple sets of second pre-adhesive are alternately arranged on both sides of the second welding area.

[0032] This utility model also provides a battery string, comprising:

[0033] Several of the aforementioned back contact batteries; and

[0034] The welding strips are disposed on the first welding area and the second welding area. The welding strips on the first welding area are connected to the first pre-adhesive and in contact with the first weld point. The welding strips on the second welding area are connected to the second pre-adhesive and in contact with the second weld point.

[0035] This utility model also provides a battery assembly, including the battery string described above.

[0036] This utility model also provides a photovoltaic system, including the above-mentioned battery components.

[0037] This utility model provides a back contact battery by setting at least one first offset solder point on the same first fine grid with an offset direction opposite to that of at least one other first offset solder point. Even if the solder strips corresponding to the first welding area are offset from the first welding area in the second direction, because the offset direction of at least one first offset solder point on the first fine grid with the first offset solder point is opposite to that of at least one other first offset solder point, the offset direction of at least one first offset solder point will be the same as that of the solder strip. Therefore, it can be ensured that at least one first offset solder point on the first fine grid with the first offset solder point is in contact with the corresponding solder strip, ensuring that each first fine grid can be electrically connected to the corresponding solder strip, and that the charge carriers collected by each first fine grid can be gathered to the solder strip, greatly reducing the risk that the solder strip cannot make electrical contact with some first fine grids due to solder strip offset; at the same time, setting the same The offset direction of at least one second offset solder point on a second fine grid is opposite to the offset direction of at least one other second offset solder point. Even if each solder strip in the corresponding second welding area is offset from the second welding area in the second direction, since the offset direction of at least one second offset solder point on the second fine grid with the second offset solder point is opposite to the offset direction of at least one other second offset solder point, at least one second offset solder point will be in the same offset direction as the solder strip. Therefore, it can be ensured that at least one second offset solder point on the second fine grid with the second offset solder point is in contact with the corresponding solder strip, ensuring that each second fine grid can be electrically connected to the corresponding solder strip. This allows the charge carriers collected by each second fine grid to be gathered to the solder strip, greatly reducing the risk that the solder strip cannot make electrical contact with some second fine grids due to solder strip offset, thereby ensuring good power generation efficiency of the battery module composed of back contact cells. Attached Figure Description

[0038] Figure 1 A plan view of a back contact battery provided for an embodiment of this utility model;

[0039] Figure 2 for Figure 1 A magnified schematic diagram of part A in the middle;

[0040] Figure 3 A partial structural schematic diagram of a back contact battery provided in an embodiment of this utility model;

[0041] Figure 4 A schematic diagram of a back contact battery connected to a solder strip is provided for an embodiment of this utility model;

[0042] Figure 5 A schematic diagram of the module structure of the battery string provided in an embodiment of this utility model;

[0043] Figure 6 A schematic diagram of the module structure of the battery assembly provided in an embodiment of this utility model;

[0044] Figure 7 A schematic diagram of the module structure of a photovoltaic system provided in an embodiment of this utility model. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present utility model, and should not be construed as limiting the present utility model. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining the present utility model and are not intended to limit the present utility model.

[0046] In the description of this utility model, it should be understood that the terms "upper", "lower", "back", "front", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0047] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0048] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0049] Please refer to Figures 1-4This utility model embodiment provides a back contact battery 100, comprising:

[0050] Silicon substrate 1;

[0051] A plurality of first fine gates 2 and a plurality of second fine gates 3 are disposed on the back side 11 of the silicon substrate 1. The plurality of first fine gates 2 and the plurality of second fine gates 3 are arranged alternately along the first direction Y. The first fine gates 2 and the second fine gates 3 both extend along the second direction X, and the second direction X intersects the first direction Y. The back side 11 has a first welding area 111 and a second welding area 112 for setting the solder strip 20. The first welding area 111 and the second welding area 112 are arranged alternately along the second direction X. The first welding area 111 and the second welding area 112 both extend along the first direction Y.

[0052] A first pre-adhesive 4 is disposed on at least one side of the first welding area 111, and the first pre-adhesive 4 extends at least partially into the first welding area 111;

[0053] A first solder point 5 is provided on the first fine grid 2 and located in the first welding area 111. The first solder point 5 includes a first offset solder point 51 offset from the central axis L1 of the first welding area 111 in a direction away from the corresponding first pre-adhesive 4. The offset direction of at least one first offset solder point 51 on the same first fine grid 2 is opposite to the offset direction of the other at least one first offset solder point 51.

[0054] A second pre-adhesive 6 is disposed on at least one side of the second welding area 112, and the second pre-adhesive 6 extends at least partially into the second welding area 112; and

[0055] The second solder joint 7 is provided on the second fine grid 3. The second solder joint 7 is located in the second welding area 112. The second solder joint 7 includes a second offset solder joint 71 that is offset away from the central axis L2 of the second welding area 112 in a direction away from the corresponding second pre-adhesive 6. The offset direction of at least one second offset solder joint 71 on the same second fine grid 3 is opposite to the offset direction of the other at least one second offset solder joint 71.

[0056] In this embodiment of the invention, the front side of the silicon substrate 1 is used to receive sunlight, and the back side 11 of the silicon substrate 1 includes multiple alternating first doped layers and second doped layers (not shown). A first fine gate 2 is disposed on the first doped layer, and a second fine gate 3 is disposed on the second doped layer. The first fine gate 2 and the second fine gate 3 extend along a second direction X and are alternately disposed along a first direction Y; simultaneously, the first doped layer and the second doped layer also extend along the second direction X and are alternately disposed along the first direction Y. In this embodiment of the invention, the back side 11 of the silicon substrate 1 has no main gate, and the first fine gate 2 and the second fine gate 3 can directly achieve current convergence through the solder ribbon 20. The polarities of the first fine gate 2 and the second fine gate 3 are opposite. The first solder area 111 and the second solder area 112 are respectively used to dispose of the solder ribbon 20, and the first solder area 111 and the second solder area 112 extend along the first direction Y and intersect with the first fine gate 2 and the second fine gate 3.

[0057] In this embodiment of the invention, the doping types of the first and second doped layers are not limited. For example, the first and second doped layers can be P-type and N-type doped layers, respectively; alternatively, the first doped layer can be N-type and the second doped layer can be P-type, as long as their polarities are opposite to meet different requirements. In some embodiments, the first doped layer can be a P-type polycrystalline silicon layer, a P-type amorphous silicon layer, or a P-type microcrystalline silicon layer, and there is no specific limitation. Similarly, the second doped layer can be an N-type polycrystalline silicon layer, an N-type amorphous silicon layer, or an N-type microcrystalline silicon layer, and there is no specific limitation. When the first doped layer is a P-type doped layer and the second doped layer is an N-type doped layer, P-type gate lines can also be provided on the first doped layer, and N-type gate lines can also be provided on the second doped layer, and there is no specific limitation.

[0058] In some embodiments, P-type doping refers to doping with group III elements, including boron, aluminum, gallium, indium, thallium, etc.; N-type doping refers to doping with group V elements, including nitrogen, phosphorus, arsenic, antimony, bismuth, etc., and the specific doping is not limited here. Specifically, the first direction Y and the second direction X can be the longitudinal direction and the transverse direction of the back contact battery, respectively. Of course, in other embodiments, the first direction Y and the second direction X can also be other directions, for example, they can be the diagonal directions of the silicon substrate 1, and the specific doping is not limited here.

[0059] The back contact battery provided in this embodiment of the utility model is configured such that the offset direction of at least one first offset solder point 51 on the same first fine grid 2 is opposite to the offset direction of at least one other first offset solder point 51. This can be achieved by having one first offset solder point 51 on the same first fine grid 2 with an offset direction opposite to the offset direction of all other first offset solder points 51, or by having two or more first offset solder points 51 on the same first fine grid 2 with offset directions opposite to the offset directions of the other first offset solder points 51. It is only necessary to ensure that at least one first offset solder point 51 on the first fine grid 2 with the first offset solder point 51 has an offset direction opposite to the offset direction of at least one other first offset solder point 51. Even if each solder strip 20 corresponding to the first welding area 111 is respectively connected to the first welding area 111 in the second direction X... When there is a certain offset, that is, when the central axis of each solder strip 20 does not coincide with the central axis L1 of the corresponding first welding area 111 in the second direction X, since the offset direction of at least one first offset solder point 51 on the first fine grid 2 is opposite to the offset direction of the other at least one first offset solder point 51, at least one first offset solder point 51 will be in the same offset direction as the solder strip 20. Therefore, it can be ensured that at least one first offset solder point 51 on the first fine grid 2 with the first offset solder point 51 is in contact with the corresponding solder strip 20, ensuring that the charge carriers collected by each first fine grid 2 can be gathered to the solder strip 20, realizing the effective collection of charge carriers of each first fine grid 2, greatly reducing the risk that the solder strip 20 and some first fine grid 2 cannot make electrical contact due to the offset of the solder strip 20, and ensuring the good power generation efficiency of the battery module composed of back contact cells.

[0060] Simultaneously, by setting the offset direction of at least one second offset solder point 71 on the same second fine gate 3 to be opposite to the offset direction of at least one other second offset solder point 71, it can be that one second offset solder point 71 on the same second fine gate 3 has an offset direction opposite to all the other second offset solder points 71, or that two or more second offset solder points 71 on the same second fine gate 3 have an offset direction opposite to the other second offset solder points 71, such that at least one second offset solder point 71 on the second fine gate 3 with second offset solder points 71 has an offset direction opposite to the offset direction of the other second offset solder points 71; even corresponding to the second Each solder strip 20 in the welding area 112 is offset from the central axis L2 of the second welding area 112 in the second direction X. This will cause at least one second offset solder point 71 to be offset in the same direction as the solder strip 20. Therefore, it can be ensured that at least one second offset solder point 71 on the second fine grid 3 with the second offset solder point 71 is in contact with the corresponding solder strip 20. This ensures that the charge carriers collected by each second fine grid 3 can be gathered to the solder strip 20, realizing the effective collection of charge carriers by each second fine grid 3. This greatly reduces the risk that the solder strip cannot make electrical contact with some of the second fine grid 3 due to the offset of the solder strip, and ensures the good power generation efficiency of the battery module composed of back contact cells.

[0061] In this embodiment of the invention, the first offset solder point 51 is offset away from the central axis L1 of the first welding area 111 in a direction away from the corresponding first pre-adhesive 4. This can be understood as the center point of the first offset solder point 51 not coinciding with the central axis L1 of the first welding area 111, and the center point of the first offset solder point 51 being located on the side of the central axis L1 of the first welding area 111 away from the corresponding first pre-adhesive 4. The number of first offset solder points 51 in the first welding area 111 can be equal to or different from the number of first pre-adhesive 4. That is, each first offset solder point 51 can correspond to one first pre-adhesive 4, multiple first offset solder points 51 can correspond to one first pre-adhesive 4, or one first offset solder point 51 can correspond to multiple first pre-adhesive 4s.

[0062] Similarly, the second offset solder point 71 is offset away from the central axis L2 of the second welding area 112, away from the corresponding second pre-adhesive 6. This can be understood as the center point of the second offset solder point 71 not coinciding with the central axis L2 of the second welding area 112, and the center point of the second offset solder point 71 being located on the side of the central axis L2 of the second welding area 112 away from the corresponding second pre-adhesive 6. The number of second offset solder points 71 in the second welding area 112 can be equal to or different from the number of second pre-adhesive 6. That is, each second offset solder point 71 can correspond to one second pre-adhesive 6, multiple second offset solder points 71 can correspond to one second pre-adhesive 6, or one second offset solder point 71 can correspond to multiple second pre-adhesive 6.

[0063] Furthermore, the offset distance of the first offset solder joint 51 relative to the central axis L1 of the first welding area 111 is unlimited, and the offset distances of the first offset solder joints 51 within the same first welding area 111 can be the same or different. Similarly, the offset distance of the second offset solder joint 71 relative to the central axis L2 of the second welding area 112 is unlimited, and the offset distances of the second offset solder joints 71 within the same second welding area 112 can be the same or different.

[0064] As an embodiment of this utility model, the offset directions of two adjacent first offset solder points 51 on the same first fine grid 2 are opposite.

[0065] In this embodiment, among two adjacent first offset solder points 51 on the same first fine gate 2, one first offset solder point 51 is offset towards the first side of the silicon substrate 1 relative to the central axis L1 of the first welding area 111, and the other first offset solder point 51 is offset towards the second side of the silicon substrate 1 relative to the central axis L1 of the first welding area 111, and the first side and the second side of the silicon substrate 1 are disposed opposite to each other. For example, among two adjacent first offset solder points 51 on the same first fine gate 2, one first offset solder point 51 is offset to the left of the central axis L1 of the first welding area 111, and the other first offset solder point 51 is offset to the right of the central axis L1 of the first welding area 111.

[0066] In this embodiment, since the offset directions of two adjacent first offset solder points 51 on the same first fine grid 2 are opposite, even if each solder strip 20 corresponding to the first welding area 111 is offset from the first welding area 111 in the second direction X, the offset direction of one of the two adjacent first offset solder points 51 is the same as the offset direction of the solder strip 20. This makes one of the two adjacent solder strips 20 of the same polarity coincide with the position of one of the two adjacent first offset solder points 51 of the first fine grid 2, thereby ensuring that one of the two adjacent solder strips 20 of the same polarity contacts the one of the two adjacent first offset solder points 51 of the first fine grid 2. This further improves the reliability of the solder strip 20 and each first fine grid 2, so that the charge carriers collected by each first fine grid 2 can be gathered to the solder strip 20, realizing the effective collection of charge carriers of each first fine grid 2 and ensuring good power generation efficiency of the battery module.

[0067] As an embodiment of this utility model, the offset directions of two adjacent second offset solder points 71 on the same second fine grid 3 are opposite.

[0068] In this embodiment, the offset directions of two adjacent second offset solder points 71 on the same second fine gate 3 are opposite. This can be understood as follows: of the two adjacent second offset solder points 71 on the same second fine gate 3, one second offset solder point 71 is offset relative to the central axis L2 of the second welding area 112 towards the first side of the silicon substrate 1, and the other second offset solder point 71 is offset relative to the central axis L2 of the second welding area 112 towards the second side of the silicon substrate 1, with the first side of the silicon substrate 1 and the second side of the silicon substrate 1 being opposite to each other. For example, of the two adjacent second offset solder points 71 on the same second fine gate 3, one second offset solder point 71 is offset to the left of the central axis L2 of the second welding area 112, and the other second offset solder point 71 is offset to the right of the central axis L2 of the second welding area 112.

[0069] In this embodiment, since the offset directions of two adjacent second offset solder points 71 on the same second fine grid 3 are opposite, even if each solder strip 20 is offset from the corresponding second welding area 112 in the second direction X, it can be ensured that one of the two solder strips 20 corresponding to the adjacent second welding area 112 coincides with one of the two adjacent second offset solder points 71 of the second fine grid 3. This ensures that one of the two adjacent solder strips 20 is in contact with one of the two adjacent second offset solder points 71 of the second fine grid 3, further improving the reliability of the solder strip 20 and each fine grid welding. This enables the carriers collected by each second fine grid 3 to be gathered to the solder strip 20, achieving effective carrier collection of each second fine grid 3 and ensuring good power generation efficiency of the battery module.

[0070] As an embodiment of the present invention, the first solder joint 5 further includes a first central solder joint 52 located on the central axis L1 of the first welding area 111, and a portion of the first fine grid 2 is provided with the first central solder joint 52. The first offset solder joint 51 is offset relative to the first central solder joint 52 in the second direction X.

[0071] In this embodiment, a portion of the first fine grid 2 is provided with a first offset solder joint 51, and a portion of the first fine grid 2 is provided with a first center solder joint 52. The center point of the first center solder joint 52 is located at the central axis L1 of the first welding area 111, and the center point of the first offset solder joint 51 is offset from the central axis L1 of the first welding area 111, that is, the first offset solder joint 51 is offset relative to the first center solder joint 52 in the second direction X. Moreover, the number of first center solder joints 52 and first offset solder joints 51 is unlimited.

[0072] In this embodiment, the first welding area 111 of the silicon substrate 1 is simultaneously welded to the solder strip 20 using the first center solder point 52 and the first offset solder point 51, which can further improve the welding effect between the first welding area 111 of the silicon substrate 1 and the solder strip 20, and improve the connection reliability between the solder strip 20 and the first welding area 111.

[0073] As an embodiment of the present invention, the second solder point 7 includes a second central solder point 72 located on the central axis L2 of the second welding area 112, a second central solder point 72 is provided on a portion of the second fine grid 3, and a second offset solder point 71 is offset relative to the second central solder point 72 in the second direction X.

[0074] In this embodiment, some of the second fine grids 3 are provided with second offset solder joints 71, and some of the second fine grids 3 are provided with second center solder joints 72. The center point of the second center solder joint 72 is located at the central axis L2 of the second welding area 112, and the center point of the second offset solder joint 71 is offset from the central axis L2 of the second welding area 112. The second offset solder joint 71 is offset relative to the second center solder joint 72 in the second direction X. The number of second center solder joints 72 and second offset solder joints 71 is not limited.

[0075] In this embodiment, the second welding area 112 of the silicon substrate 1 is simultaneously welded to the solder strip 20 using the second center solder point 72 and the second offset solder point 71, which can further improve the welding effect between the second welding area 112 of the silicon substrate 1 and the solder strip 20, and improve the connection reliability between the solder strip 20 and the second welding area 112.

[0076] As an embodiment of the present invention, all first weld points 5 of two adjacent first welding areas 111 are arranged in a mirror symmetric manner, and all second weld points 7 of two adjacent second welding areas 112 are arranged in a mirror symmetric manner.

[0077] In this embodiment, all the first solder points 5 of two adjacent first welding areas 111 are arranged in a mirror symmetrical manner, which can make each solder strip 20 of the corresponding first welding area 111 offset from the first welding area 111 in the second direction X. This ensures that one of the two adjacent solder strips 20 of the corresponding first welding area 111 is in contact with one of the two adjacent first offset solder points 51 of the first fine gate 2, thereby improving the reliability of the solder strip 20 and each first fine gate 2. This enables the carriers collected by each first fine gate 2 to be gathered to the solder strip 20, thus achieving effective carrier collection of each first fine gate 2. Similarly, all the second solder points 7 of two adjacent second welding areas 112 are arranged in a mirror symmetry, which can ensure that one of the two adjacent solder strips 20 of the corresponding second welding area 112 is in contact with one of the two adjacent second offset solder points 71 of the second fine gate 3, thereby improving the reliability of the solder strip 20 and each second fine gate 3 welding, and realizing that the charge carriers collected by each second fine gate 3 can be gathered to the solder strip 20, thus realizing the effective charge carrier collection of each second fine gate 3.

[0078] As an embodiment of the present invention, a plurality of first offset solder points 51 are arranged sequentially along the first direction Y in the first welding area 111, and each group of first offset solder points 51 includes a plurality of first offset solder points 51 arranged at intervals along the first direction Y.

[0079] In this embodiment, the number of first offset solder points 51 included in each group of first offset solder points 51 is not limited. Each group of first offset solder points 51 may include one, two, or multiple first offset solder points 51. Multiple groups of first offset solder points 51 are provided in the first welding area 111, and each group of first offset solder points 51 includes several first offset solder points 51, which is beneficial to improving the welding effect between the first welding area 111 and the solder strip 20.

[0080] As an embodiment of the present invention, each second welding area 112 is provided with a plurality of second offset solder points 71 arranged sequentially along the first direction Y, and each group of second offset solder points 71 includes a plurality of second offset solder points 71 arranged at intervals along the first direction Y.

[0081] In this embodiment, the number of second offset solder points 71 included in each group of second offset solder points 71 is not limited. Each group of second offset solder points 71 may include one, two, or multiple second offset solder points 71. Multiple groups of second offset solder points 71 are provided in the second welding area 112, and each group of second offset solder points 71 includes several second offset solder points 71, which is beneficial to improving the welding effect between the second welding area 112 and the solder strip 20.

[0082] As an embodiment of the present invention, a plurality of first central solder joints 52 are arranged sequentially along the first direction Y in the first welding area 111. Each group of first central solder joints 52 includes at least one first central solder joint 52. The plurality of first central solder joints 52 and the plurality of first offset solder joints 51 are alternately arranged along the first direction Y.

[0083] In this embodiment, the number of first center solder joints 52 included in each group of first center solder joints 52 is not limited. Each group of first center solder joints 52 may include one, two, or multiple first center solder joints 52. In particular, multiple groups of first center solder joints 52 and multiple groups of first offset solder joints 51 are alternately arranged, which is beneficial to further improve the welding effect between the first welding area 111 and the solder strip 20.

[0084] As an embodiment of the present invention, the second welding area 112 is provided with a plurality of second central weld points 72 arranged sequentially along the first direction Y. Each group of second central weld points 72 includes a plurality of second central weld points 72 arranged at intervals along the first direction Y. The plurality of groups of second central weld points 72 and the plurality of groups of second offset weld points 71 are alternately arranged along the first direction Y.

[0085] In this embodiment, the number of second center solder joints 72 included in each group of second center solder joints 72 is not limited. Each group of second center solder joints 72 may include one, two, or multiple second center solder joints 72. The alternation of multiple groups of second center solder joints 72 is beneficial to further improve the welding effect between the second welding area 112 and the solder strip 20.

[0086] As an embodiment of the present invention, two adjacent first pre-adhesives 4 located at the same position in the first direction Y have opposite offset directions relative to the corresponding first welding area 111; and / or, two adjacent second pre-adhesives 6 located at the same position in the first direction Y have opposite offset directions relative to the corresponding second welding area 112.

[0087] In this embodiment, two adjacent first pre-adhesives 4 located at the same position in the first direction Y have opposite offset directions relative to their corresponding first welding areas 111. This can be understood as follows: of the two adjacent first pre-adhesives 4 located at the same position in the first direction Y, one first pre-adhesive 4 is located on the first side of its first welding area 111 near the silicon substrate 1, and the other first pre-adhesive 4 is located on the second side of its first welding area 111 near the silicon substrate 1, with the first side of the silicon substrate 1 and the second side of the silicon substrate 1 opposite to each other. For example, of the two adjacent first pre-adhesives 4 located at the same position in the first direction Y, one first pre-adhesive 4 is located on the left side of its first welding area 111, and the other first pre-adhesive 4 is located on the right side of its first welding area 111. Because the offset directions of two adjacent first pre-adhesives 4 at the same position in the first direction Y are opposite relative to the corresponding first welding area 111, the offset directions of two adjacent first offset solder points 51 at the same position in the first direction Y are also opposite. Even if the solder ribbon 20 is offset, one of the two adjacent first offset solder points 51 can maintain contact with the solder ribbon 20. Similarly, the offset directions of two adjacent second pre-adhesives 6 at the same position in the first direction Y are opposite relative to the corresponding second welding area 112, causing the offset directions of two adjacent second offset solder points 71 at the same position in the first direction Y to be opposite. Even if the solder ribbon 20 is offset, one of the two adjacent second offset solder points 71 can maintain contact with the solder ribbon 20.

[0088] As an embodiment of the present invention, each first welding area 111 is provided with a plurality of first pre-adhesives 4 arranged sequentially along the first direction Y, and the plurality of first pre-adhesives 4 are alternately arranged on both sides of the first welding area 111.

[0089] In this embodiment, multiple sets of first pre-adhesive 4 are alternately arranged on both sides of the first welding area 111, which allows multiple sets of first pre-adhesive 4 to simultaneously bond and fix both sides of the welding strip 20, thereby improving the pre-fixation effect of the welding strip 20. The number of first pre-adhesive 4 included in each set is not limited; it can be one, two, or more.

[0090] As an embodiment of the present invention, each second welding area 112 is provided with a plurality of sets of second pre-adhesives 6 arranged sequentially along the first direction Y, and the sets of second pre-adhesives 6 are alternately arranged on both sides of the second welding area 112.

[0091] In this embodiment, multiple sets of second pre-adhesive 6 are alternately arranged on both sides of the second welding area 112, which allows multiple sets of second pre-adhesive 6 to simultaneously bond and fix both sides of the welding strip 20, thereby improving the pre-fixation effect of the welding strip 20. The number of second pre-adhesive 6 included in each set is not limited; it can be one, two, or more.

[0092] As an embodiment of the present invention, each first welding area 111 has at least two sets of first offset solder points 51 with opposite offset directions, and each second welding area 112 has at least two sets of second offset solder points 71 with opposite offset directions.

[0093] In this embodiment, at least two sets of first offset solder points 51 within each first welding area 111 are offset in opposite directions, and at least two sets of second offset solder points 71 within each second welding area 112 are offset in opposite directions. This is beneficial for further improving the welding effect between the first welding area 111 and the second welding area 112 and the solder strip 20. Preferably, the offset directions of two adjacent sets of first offset solder points 51 within each first welding area 111 are opposite, which is beneficial for improving the welding effect of the solder strip 20.

[0094] As an embodiment of the present invention, the center points of all the first weld points in each first welding area 111 are connected to form a first line segment 12. The first line segment 12 includes a first straight line segment 121 formed by sequentially connecting the center points of each group of first center weld points 52 and a first curved segment 122 formed by sequentially connecting the center points of each group of first offset weld points 51. The first curved segment 122 is curved relative to the first straight line segment 121, and the two first curved segments 122 located at the same position in the first direction Y in two adjacent first welding areas 111 have opposite bending directions.

[0095] In this embodiment, the first line segment 12 may specifically include multiple first straight segments 121 and multiple first curved segments 122. The first straight segments 121 and the first curved segments 122 may be arranged alternately or non-alternatingly. The center points of each group of first offset solder points 51 are sequentially connected to form a first curved segment 122 that curves relative to the first straight segment 121. This distribution of the first offset solder points 51 is beneficial for improving the welding effect between the first welding area 111 and the solder strip 20. Furthermore, the first curved segments 122 located at the same position in the first direction Y within adjacent first welding areas 111 have opposite bending directions. This ensures that even if the solder strip 20 is offset, each first fine grid 2 will still have a first offset solder point 51 that can maintain contact with the solder strip 20.

[0096] As an embodiment of the present invention, the line connecting the center points of all the second weld points 7 in each second welding area 112 forms a second line segment 13. The second line segment 13 includes a second straight line segment 131 formed by sequentially connecting the center points of each group of second center weld points 72 and a second curved segment 132 formed by sequentially connecting the center points of each group of second offset weld points 71. The second curved segment 132 is curved relative to the second straight line segment 131. The two second curved segments 132 located at the same position in the first direction Y in two adjacent second welding areas 112 have opposite bending directions.

[0097] In this embodiment, the second line segment 13 may specifically include multiple second straight segments 131 and multiple second curved segments 132. The second straight segments 131 and the second curved segments 132 may be arranged alternately or non-alternatingly. The center points of each group of second offset solder points 71 are sequentially connected to form a second curved segment 132 that curves relative to the second straight segment 131. This distribution of the second offset solder points 71 is more conducive to improving the welding effect between the first welding area 112 and the solder strip 20. Moreover, the bending directions of the second curved segments 132 located at the same position in the first direction Y within adjacent second welding areas 112 are opposite. Even if the solder strip 20 and the second welding area 112 are offset, it can be ensured that the corresponding second offset solder points 71 on the second fine grid 3 with the second offset solder points 71 can maintain contact with the solder strip 20.

[0098] As an embodiment of this utility model, the first solder joint 5 further includes:

[0099] Multiple first edge solder points 53 are disposed on a first fine gate 2 near the edge of the silicon substrate 1, and the multiple first edge solder points 53 are arranged sequentially at intervals along the second direction X.

[0100] In this embodiment, the number of first edge solder joints 53 provided on the first fine gate 2 near the edge of the silicon substrate 1 is not limited, and can be two, three or more. Specifically, first edge solder joints 53 are provided on the two first fine gates 2 near the edge of the silicon substrate 1 along the first direction Y. Because multiple first edge solder joints 53 are provided near the edge of the silicon substrate 1 within the first welding area 111, it is beneficial to increase the welding pull between the first welding area 111 near the edge of the silicon substrate 1 and the solder strip 20, thereby improving the welding effect between the first welding area 111 and the solder strip 20. The shapes and sizes of the first edge solder joints 53, the first center solder joint 52, and the first offset solder joint 51 can be the same or different. Preferably, the area of ​​the first edge solder joint 53 is larger than the area of ​​the first center solder joint 52 and the first offset solder joint 51, which further increases the welding pull between the first welding area 111 near the edge of the silicon substrate 1 and the solder strip 20.

[0101] As an embodiment of this utility model, the second solder joint 7 further includes:

[0102] Multiple second edge solder points 73 are disposed on the second fine gate 3 near the edge of the silicon substrate 1, and the multiple second edge solder points 73 are arranged sequentially at intervals along the second direction X.

[0103] In this embodiment, the number of second edge solder joints 73 is not limited and can be two, three, or more. Specifically, two second fine gates 3 near the edge of the silicon substrate 1 along the first direction Y are respectively provided with second edge solder joints 73. Because multiple second edge solder joints 73 are provided near the edge of the silicon substrate 1 within the second welding area 112, it is beneficial to increase the welding pull between the second welding area 112 near the edge of the silicon substrate 1 and the solder strip 20, thereby improving the welding effect between the second welding area 112 and the solder strip 20. Preferably, the area of ​​the second edge solder joints 73 is larger than the area of ​​the second center solder joint 72 and the second offset solder joint 71, which further increases the welding pull between the second welding area 112 near the edge of the silicon substrate 1 and the solder strip 20.

[0104] Please refer to point 4 and... Figure 5 This utility model embodiment also provides a battery string 200, comprising:

[0105] The back contact battery 100 of several embodiments described above; and

[0106] The welding strip 20 is disposed on the first welding area 111 and the second welding area 112. The welding strip 20 on the first welding area 111 is connected to the first pre-adhesive 4 and contacts the first weld point 5. The welding strip 20 on the second welding area 112 is connected to the second pre-adhesive 6 and contacts the second weld point 7.

[0107] It is understood that in the battery string 200, the battery string 200 may include two back contact batteries 100 connected in series, three back contact batteries 100 connected in series, or a greater number of other back contact batteries 100. The specific number of battery cells to be connected in series can be determined according to the actual usage. In addition, in this embodiment, the size and type of the battery cells are not limited. Adjacent battery cells can have the same specifications and dimensions or different specifications to meet different needs.

[0108] Specifically, the solder strip 20 includes a first solder strip 201 and a second solder strip 202. The first solder strip 201 is disposed in the first welding area 111 and connected to the first fine grid 2. The second solder strip 202 can be disposed in the second welding area 112 and connected to the second fine grid 3. At this time, an insulating layer is disposed between the first solder strip 201 and the second fine grid 3 to achieve insulation, and an insulating layer is disposed between the second solder strip 202 and the first fine grid 2 to achieve insulation.

[0109] It should be noted that the battery string 200 has the same or similar beneficial effects as the back contact battery 100 described above, and the relevant parts between the two can be referred to each other. To avoid repetition, they will not be described again here.

[0110] Please refer to the reference. Figure 6 This utility model embodiment also provides a battery assembly 300, which includes the battery string 200 of the above embodiment. It should be noted that the battery assembly 300 has the same or similar beneficial effects as the back contact battery 100 described above, and the related parts between the two can be referred to each other. To avoid repetition, they will not be described again here.

[0111] Specifically, in the process of forming a battery module, the battery strings can be welded first, and then laminated to form the module. Alternatively, the back contact cells can be placed on the front panel and the adhesive film according to the module template, then solder ribbons are placed for pre-fixation, and finally lamination and welding are performed to directly form the battery module. During the lamination process, the individual back contact cells naturally form battery strings 200. It is understood that in such an embodiment, the back contact cell 100 may also include a frame, a back panel, photovoltaic glass, and an adhesive film. The adhesive film can fill the front and back sides 11 of the battery cells, as well as between the photovoltaic glass and adjacent battery cells. As a filler, it can be a transparent colloid with good light transmittance and aging resistance. For example, the adhesive film can be EVA film or POE film, and the specific choice can be made according to the actual situation, without limitation. Photovoltaic glass can be applied to the encapsulating film on the front side of the solar cell. This photovoltaic glass can be ultra-clear glass, possessing high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can achieve a light transmittance of over 92%, protecting the solar cell while minimizing impact on its efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and the solar cell together, providing sealing, insulation, and waterproofing. A backsheet can be attached to the encapsulating film on the back side of the solar cell. The backsheet protects and supports the solar cell, offering reliable insulation, water resistance, and aging resistance. Multiple backsheet options are available, typically including tempered glass, acrylic glass, and aluminum alloy TPT composite encapsulating film, with specific choices depending on the specific circumstances. No restrictions are imposed here. The backsheet, solar cells, encapsulant film, and photovoltaic glass can be mounted on the frame. The frame serves as the main external support structure for the entire back contact battery 100 and can provide stable support and installation for the back contact battery 100. For example, the back contact battery 100 can be installed at the desired location via the frame.

[0112] Please refer to the reference. Figure 7 This utility model embodiment also provides a photovoltaic system 400, which includes the battery module 300 of the above embodiment. It should be noted that the photovoltaic system 400 has the same or similar beneficial effects as the back contact battery 100 described above, and the related parts between the two can be referred to each other. To avoid repetition, they will not be described again here.

[0113] In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0114] In the description of this specification, references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0115] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A back-contact battery, characterized in that, include: Silicon substrate; A plurality of first fine gates and a plurality of second fine gates are disposed on the back side of the silicon substrate, the first fine gates and the second fine gates being arranged alternately and spaced apart along a first direction, and both the first fine gates and the second fine gates extending along a second direction, the second direction intersecting the first direction; the back side has a first welding area and a second welding area arranged alternately and spaced apart along the second direction; A first pre-adhesive is provided on at least one side of the first welding area, and the first pre-adhesive extends at least partially into the first welding area; A first solder joint is provided on the first fine grid and located in the first welding area. The first solder joint includes a first offset solder joint that is offset away from the central axis of the first welding area from the direction corresponding to the first pre-adhesive. The offset direction of at least one first offset solder joint on the same first fine grid is opposite to the offset direction of the other at least one first offset solder joint. A second pre-adhesive is provided on at least one side of the second welding area, and the second pre-adhesive extends at least partially into the second welding area; and A second solder joint is provided on the second fine grid and located in the second welding area. The second solder joint includes a second offset solder joint that is offset away from the central axis of the second welding area in the direction corresponding to the second pre-adhesive. The offset direction of at least one second offset solder joint on the same second fine grid is opposite to the offset direction of the other at least one second offset solder joint.

2. The back contact battery according to claim 1, characterized in that, The offset directions of two adjacent first offset solder points on the same first fine grid are opposite.

3. The back contact battery according to claim 1, characterized in that, The offset directions of two adjacent second offset solder points on the same second fine grid are opposite.

4. The back contact battery according to claim 1, characterized in that, The first solder joint also includes a first central solder joint located on the central axis of the first welding area. The first central solder joint is provided on a portion of the first fine grid. The first offset solder joint is offset relative to the first central solder joint in the second direction.

5. The back contact battery according to claim 1, characterized in that, The first welding area is provided with multiple sets of first offset solder points arranged sequentially along the first direction, and each set of first offset solder points includes a plurality of first offset solder points arranged at intervals along the first direction.

6. The back contact battery according to claim 5, characterized in that, Within each of the first welding zones, there are at least two sets of the first offset weld points with opposite offset directions.

7. The back contact battery according to claim 4, characterized in that, The first welding area is provided with multiple sets of first center weld points arranged sequentially along the first direction. Each set of first center weld points includes at least one first center weld point. The multiple sets of first center weld points and multiple sets of first offset weld points are alternately arranged along the first direction.

8. The back contact battery according to claim 7, characterized in that, A first line segment is formed by connecting the center points of all the first weld points in each first welding area. The first line segment includes a first straight line segment formed by sequentially connecting the center points of each group of first central weld points and a first curved segment formed by sequentially connecting the center points of each group of first offset weld points. The first curved segment is curved relative to the first straight line segment, and the two first curved segments of two adjacent first welding areas located at the same position in the first direction have opposite curvature directions.

9. The back contact battery according to claim 1, characterized in that, The second solder joint includes a second central solder joint located on the central axis of the second welding area, and a portion of the second fine grid is provided with the second central solder joint. The second offset solder joint is offset relative to the second central solder joint in the second direction.

10. The back contact battery according to claim 1, characterized in that, Each second welding zone is provided with multiple sets of second offset weld points arranged sequentially along the first direction, and each set of second offset weld points includes a plurality of second offset weld points arranged at intervals along the first direction.

11. The back contact battery according to claim 10, characterized in that, Within each second welding zone, there are at least two sets of second offset weld points with opposite offset directions.

12. The back contact battery according to claim 9, characterized in that, The second welding area is provided with multiple sets of second center weld points arranged sequentially along the first direction. Each set of second center weld points includes at least one second center weld point. The multiple sets of second center weld points and multiple sets of second offset weld points are alternately arranged along the first direction.

13. The back contact battery according to claim 12, characterized in that, The line connecting the center points of all the second weld points in each second welding area forms a second line segment. The second line segment includes a second straight line segment formed by sequentially connecting the center points of each group of second center weld points and a second curved segment formed by sequentially connecting the center points of each group of second offset weld points. The second curved segment is curved relative to the second straight line segment. The two second curved segments located at the same position in the first direction in two adjacent second welding areas have opposite curvature directions.

14. The back contact battery according to claim 1, characterized in that, All first weld points in two adjacent first welding areas are arranged in a mirror-symmetric manner, and / or all second weld points in two adjacent second welding areas are arranged in a mirror-symmetric manner.

15. The back contact battery according to claim 1, characterized in that, The first solder joint also includes: A plurality of first edge solder joints are disposed on the first fine gate near the edge of the silicon substrate, and the plurality of first edge solder joints are arranged sequentially at intervals along the second direction.

16. The back contact battery according to claim 1, characterized in that, The second solder joint also includes: A plurality of second edge solder joints are disposed on the second fine gate near the edge of the silicon substrate, and the plurality of second edge solder joints are arranged sequentially at intervals along the second direction.

17. The back contact battery according to claim 1, characterized in that, The offset directions of two adjacent first pre-adhesives located at the same position in the first direction relative to the corresponding first welding area are opposite; and / or, the offset directions of two adjacent second pre-adhesives located at the same position in the first direction relative to the corresponding second welding area are opposite.

18. The back contact battery according to claim 1, characterized in that, Each of the first welding areas is provided with multiple sets of the first pre-adhesive arranged sequentially along the first direction, and the multiple sets of the first pre-adhesive are alternately arranged on both sides of the first welding area.

19. The back contact battery according to claim 1, characterized in that, Each second welding area is provided with multiple sets of second pre-adhesive arranged sequentially along the first direction, and the multiple sets of second pre-adhesive are alternately arranged on both sides of the second welding area.

20. A battery string, characterized in that, include: Several back contact batteries as described in any one of claims 1 to 19; and The welding strips are disposed on the first welding area and the second welding area. The welding strips on the first welding area are connected to the first pre-adhesive and in contact with the first weld point. The welding strips on the second welding area are connected to the second pre-adhesive and in contact with the second weld point.

21. A battery assembly, characterized in that, Includes the battery string as described in claim 20.

22. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 21.

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