0BB main-grid-free tin alloy bonding pad photovoltaic cell piece and photovoltaic cell string
By setting up tin alloy pads and conductive metal welding tapes on the front of the photovoltaic cell, the problem of unstable connection between the conductive metal welding tapes and the photovoltaic cell is solved, and the dual optimization of stability and cost is achieved.
Patent Information
- Application Number
- CN202421671219.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-15
- Publication Date
- 2025-07-08
- Estimated Expiration
- 2034-07-15
AI Technical Summary
Among the existing main gateless photovoltaic cells, the stability of the conductive metal welding tape and the main body of the photovoltaic cell is insufficient, which is easy to fall off, resulting in unstable connection, and the silver is used for a large amount and high cost.
The photovoltaic cell is adopted with 0BB main gateless tin alloy pad. The front conductive pad is arranged on the front surface of the photovoltaic cell and the conductive metal welding tape are soldered. The conductive covering part made of tin alloy is heated to the front surface conductive pad at low temperature, replacing the traditional UV curing glue fixing, improving the connection stability, and reducing stress through the spacing and interlacing of the front conductive pads.
The connection stability between the conductive metal welding tape and the main body of the photovoltaic cell is improved, the silver consumption is reduced, the production cost is reduced, and the risk of photovoltaic cell fragmentation is reduced.
Smart Images
Figure CN223080405U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of photovoltaic cells, and in particular, to a 0BB main-grid-free tin alloy pad photovoltaic cell and a photovoltaic cell string. Background Art
[0002] The main grid lines and fine grid lines of photovoltaic cells are generally obtained by screen printing and then sintering, resulting in a large amount of silver used, and thus the cost of photovoltaic cells is relatively high. Currently, a main-grid-free photovoltaic cell is disclosed in the related art, which deletes the main grid lines and directly electrically connects the conductive metal solder tape to the fine grid lines of the photovoltaic cell to reduce the amount of silver used and achieve the effect of reducing the cost of the photovoltaic cell. However, in this technical solution, the conductive metal solder tape is fixed to the main body of the photovoltaic cell by UV glue, resulting in a small tensile force between the conductive metal solder tape and the main body of the photovoltaic cell, and the conductive metal solder tape is likely to fall off, so that the conductive metal solder tape detaches from the fine grid lines, and thus improvement is needed. Summary of the Utility Model
[0003] The present application provides a 0BB main-grid-free tin alloy pad photovoltaic cell and a photovoltaic cell string to improve the connection stability between the conductive metal solder tape and the main body of the photovoltaic cell, thereby improving the electrical connection stability between the conductive metal solder tape and the fine grid lines.
[0004] In a first aspect, a 0BB main-grid-free tin alloy pad photovoltaic cell provided by the present application adopts the following technical solution:
[0005] A 0BB main-grid-free tin alloy pad photovoltaic cell includes a cell main body, a first electrode and a second electrode. The first electrode is disposed on the front surface of the cell main body, and the second electrode is disposed on the back surface of the cell main body and connected to the back surface of the cell main body; the first electrode includes a plurality of front fine grid lines and a plurality of front pad groups; the plurality of front fine grid lines are sequentially spaced along a first direction and are all connected to the front surface of the photovoltaic cell main body; the plurality of front pad groups are sequentially arranged at intervals along a second direction, and each front pad group includes a plurality of front conductive pads. All the front conductive pads in each front pad group are sequentially arranged along the first direction, and each front conductive pad is welded to the front surface of the cell main body. The second direction intersects the first direction; the front conductive pads and the second electrode are configured to be electrically connected to a conductive metal solder tape for connecting the cell main bodies in series, respectively.
[0006] By adopting the above technical solution, the front fine grid lines are used to collect the photo-generated carriers generated by the main body of the solar cell. The conductive metal solder tape for connecting the main bodies of the solar cells in series is welded to both the front conductive pads and the front fine grid lines, so that the current generated by the main body of the solar cell can be output through the conductive metal solder tape. Compared with the conventional technical means of fixing the conductive metal solder tape by UV curable glue, this technical solution in which the conductive metal solder tape is fixedly connected to the surface of the main body of the solar cell through the front conductive pads can improve the tensile force between the conductive metal solder tape and the main body of the solar cell, which is beneficial to improving the connection stability between the conductive metal solder tape and the main body of the solar cell, thereby improving the electrical connection stability between the conductive metal solder tape and the front fine grid lines, and at the same time saving the process cost of fixing the conductive metal solder tape. By replacing the main grid lines on the front of the main body of the solar cell with conductive metal solder tapes, the silver paste originally used to make the main grid lines is saved, so as to reduce the consumption of silver, which further helps to save costs.
[0007] Optionally, all the front conductive pads in the front pad group are arranged at intervals.
[0008] By adopting the above technical solution, the front conductive pads are arranged at intervals, which is beneficial to reducing the number of front conductive pads to reduce costs, and at the same time facilitating the release of the stress generated when the front conductive pads are welded to the main body of the solar cell, so as to reduce the risk of fragmentation of the main body of the photovoltaic solar cell.
[0009] Optionally, any front conductive pad in the front pad group and any front conductive pad in any adjacent front pad group are arranged staggered in the second direction.
[0010] By adopting the above technical solution, the front conductive pads in two adjacent front pad groups are arranged staggered with each other, which further facilitates the release of the stress generated when the front conductive pads are welded to the main body of the solar cell, and at the same time is beneficial to reducing the deformation of the main body of the photovoltaic solar cell caused by the thermal deformation of the conductive metal solder tape after welding, so as to further reduce the risk of fragmentation of the photovoltaic solar cell.
[0011] Optionally, all the front conductive pads in the front pad group are connected end to end in sequence.
[0012] Optionally, the second electrode includes a plurality of back fine grid lines and a plurality of back pad groups; the plurality of back fine grid lines are arranged at intervals in sequence along the first direction and are all connected to the back of the main body of the photovoltaic solar cell; the plurality of back pad groups are arranged at intervals in sequence along the second direction, the back pad group includes a plurality of back conductive pads, all the back conductive pads in each back pad group are arranged in sequence along the first direction, and each back conductive pad is welded to the back of the main body of the solar cell; the back conductive pads are configured to be welded to the conductive metal solder tape for connecting the main bodies of the solar cells in series.
[0013] Optionally, the second electrode includes a conductive metal film layer and a conductive pad; the conductive metal film layer is connected to the back surface of the cell body; a plurality of the back pad groups are arranged at intervals in the second direction, each back pad group includes a plurality of back conductive pads, all the back conductive pads in each back pad group are arranged in sequence in the first direction, and each back conductive pad is welded to the conductive metal film layer; the back conductive pads are configured to be welded to a conductive metal ribbon for connecting the cell bodies in series.
[0014] In a second aspect, the photovoltaic cell string provided by the present application adopts the following technical solution:
[0015] A photovoltaic cell string includes a plurality of conductive metal ribbons and a plurality of the above-mentioned 0BB main-grid-free tin alloy pad photovoltaic cells. The conductive metal ribbon includes a first part, a second part and a connecting part. The two ends of the connecting part are respectively connected to the first part and the second part. The first part is welded to the front conductive pad and electrically connected to a plurality of front fine grid lines, and the second part is electrically connected to the second electrode of another cell body.
[0016] By adopting the above technical solution, the cell bodies are connected in series with each other through the conductive metal ribbon. The conductive metal ribbon is welded to the front conductive pad and electrically connected to a plurality of front fine grid lines, which is beneficial to improving the connection stability of the conductive metal ribbon, and thus beneficial to improving the series connection stability between the cell bodies.
[0017] Optionally, the conductive metal ribbon includes a conductive core part and a conductive coating part electrically connected to the conductive core part. The conductive coating part is welded to the front conductive pad or electrically connected to the second electrode.
[0018] By adopting the above technical solution, the conductive core part is connected to the front conductive pad through the conductive coating part, which can make the material of the conductive coating part the same as or similar to that of the front conductive pad, thus being beneficial to further improving the connection stability and convenience between the conductive metal ribbon and the front conductive pad.
[0019] Optionally, the materials of the front conductive pad and the conductive coating part of the conductive metal ribbon are both tin alloy.
[0020] By adopting the above technical solution, the materials of the front conductive pad and the conductive coating part of the conductive metal ribbon are both tin alloy. The two can be connected by low-temperature heating, so as to be suitable for the production of front conductive pads of different technical photovoltaic cells and is beneficial to reducing the requirements for welding equipment and welding processes. At the same time, the material of the conductive coating part is the same as or similar to that of the front conductive pad. After heating to achieve tin-tin homogeneous melting connection, it is beneficial to further improve the connection stability between the conductive metal ribbon and the front conductive pad.
[0021] Optionally, the content of the soldering flux in the positive conductive pad and the conductive coating part of the conductive metal solder strip is zero.
[0022] By adopting the above technical solution, the positive conductive pad and the conductive coating part of the conductive metal solder strip do not contain soldering flux, which is convenient for welding the positive conductive pad to the main body of the battery cell through the ultrasonic welding process, and at the same time is convenient for welding the conductive metal solder strip to the positive conductive pad through the ultrasonic welding process, which is beneficial to improving the convenience and stability of the welding operation, and at the same time is beneficial to reducing the welding cost.
[0023] This application has at least one of the following beneficial effects:
[0024] 1. The front fine grid lines are used to collect the photo-generated carriers generated by the main body of the battery cell. By making the conductive metal solder strip used to connect the series-connected battery cell main bodies be welded to both the positive conductive pad and the front fine grid lines, the current generated by the main body of the battery cell can be output through the conductive metal solder strip. The conductive metal solder strip is fixedly connected to the main body of the battery cell through the positive conductive pad, which is beneficial to improving the tensile force between the conductive metal solder strip and the main body of the battery cell, thereby improving the stability of the connection between the conductive metal solder strip and the main body of the battery cell, and improving the stability of the electrical connection between the conductive metal solder strip and the front fine grid lines. At the same time, it saves the silver paste cost for making the main grid and the investment in printing machine equipment;
[0025] 2. The positive conductive pads are arranged at intervals and staggered, which is convenient for releasing the stress generated when the positive conductive pads are welded to the main body of the battery cell, and at the same time is beneficial to reducing the thermal deformation of the conductive metal solder strip after welding and the deformation of the main body of the photovoltaic battery cell, so as to reduce the risk of the photovoltaic battery cell being broken. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 is a schematic structural diagram of a photovoltaic battery string in an embodiment of the present application.
[0027] Figure 2 is Figure 1 a side view of a partial structure along the A direction in
[0028] Figure 3 is a schematic structural diagram of a first electrode in an embodiment of the present application.
[0029] Figure 4 is a schematic structural diagram of a second electrode in an embodiment of the present application.
[0030] Figure 5 is a schematic structural diagram of a second electrode in another embodiment of the present application.
[0031] In the figure, 100 is a photovoltaic cell string; 10 is a 0BB main-gridless tin alloy pad photovoltaic cell; 1 is a cell body; 2 is a first electrode; 21 is a front fine grid line; 22 is a front pad group; 221 is a front conductive pad; 3 is a second electrode; 31 is a back fine grid line; 32 is a back pad group; 321 is a back conductive pad; 33 is a conductive metal film layer; 20 is a conductive metal solder strip; 201 is a first part; 202 is a second part; 203 is a connecting part; X is a first direction; Y is a second direction. Specific Embodiments
[0032] The following will describe the technical solutions of the present application in conjunction with the attached Figure 1 - attached Figure 5 , and describe the technical solutions of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.
[0033] Referring to Figure 1 and Figure 2 , in an embodiment of the present application, a photovoltaic cell string 100 is provided. The photovoltaic cell string 100 includes a plurality of 0BB main-gridless tin alloy pad photovoltaic cells 10 and a plurality of conductive metal solder strips 20. The 0BB main-gridless tin alloy pad photovoltaic cell 10 includes a cell body 1, a first electrode 2, and a second electrode 3. The first electrode 2 is disposed on the front of the cell body 1, and the second electrode 3 is disposed on the back of the cell body 1.
[0034] Referring to Figure 1 and Figure 2 , in some embodiments, the conductive metal solder strip 20 includes a first part 201, a second part 202, and a connecting part 203. The first part 201, the second part 202, and the connecting part 203 are all strip-shaped, and both ends of the connecting part 203 are integrally formed and connected to the first part 201 and the second part 202 respectively. In some embodiments, the materials of the first part 201, the second part 202, and the connecting part 203 are all tin alloy. The first part 201 of the conductive metal solder strip 20 is electrically connected to the first electrode 2 located on the front of the cell body 1, and the second part 202 is electrically connected to the second electrode 3 located on the back of another cell body 1 for connecting a plurality of corresponding cell bodies 1 in series.
[0035] Referring to Figure 3, in some embodiments, the first electrode 2 includes a plurality of front fine grid lines 21 and a plurality of front pad groups 22. The plurality of front fine grid lines 21 are arranged at intervals in sequence along the first direction X and are fixedly connected to the front surface of the photovoltaic cell body 1 and electrically connected to the front surface of the cell body 1. It can be understood that, in some embodiments, the material of the front fine grid lines 21 is silver; the front fine grid lines 21 are formed on the front surface of the cell body 1 by screen printing and then sintering, and are fixedly connected to the front surface of the cell body 1 and electrically connected to the front surface of the cell body 1, so as to collect the photo-generated carriers generated by the cell body 1. In other embodiments, the material of the front fine grid lines 21 can also be aluminum or tin or other conductive materials; the front fine grid lines 21 are connected to the front surface of the cell body 1 by printing or welding.
[0036] Referring to Figure 3 , in some embodiments, the first direction X is arranged along the length direction of the cell body 1. In other embodiments, the first direction X can be arranged along the width direction of the cell body 1.
[0037] Referring to Figure 3 , the plurality of front pad groups 22 are arranged at intervals in sequence along the second direction Y, and the second direction Y intersects with the first direction X. Further, in some embodiments, the second direction Y is perpendicular to the first direction X. The front pad group 22 includes a plurality of front conductive pads 221, and all the front conductive pads 221 in each front pad group 22 are arranged in sequence along the first direction X, and each front conductive pad 221 is welded to the back surface of the cell body 1. In some embodiments, the material of the front conductive pads 221 is tin alloy.
[0038] Referring to Figures 1 to 3 , in some embodiments, the conductive metal solder tape 20 corresponds to each front pad group 22 of the first electrode 2 one by one. It can be understood that the first part 201 of the conductive metal solder tape 20 is welded and connected to all the front conductive pads 221 in the corresponding front pad group 22, and the first part 201 is welded and connected to all the corresponding front fine grid lines 21. Compared with the conventional technical means of fixing the solder tape by UV curable glue, the technical solution in which the first part 201 of the conductive metal solder tape 20 is fixedly connected to the surface of the photovoltaic cell body 1 through the front conductive pad 221 can improve the tensile force between the conductive metal solder tape 20 and the cell body 1, which is beneficial to improving the stability of the connection between the conductive metal solder tape 20 and the cell body 1, thereby improving the stability of the electrical connection between the conductive metal solder tape 20 and the front fine grid lines 21, and at the same time saving the process cost of fixing the conductive metal solder tape 20. Replacing the main grid line with the conductive metal solder tape 20 is beneficial to reducing the consumption of silver, and thus further beneficial to cost saving.
[0039] In some embodiments, the conductive metal solder strip 20 includes a conductive core and a conductive coating portion, and the conductive coating portion covers the peripheral wall of the conductive core. The conductive coating portion is used for welding with the front conductive pad 221. In some embodiments, the conductive coating portion is formed on the peripheral wall of the conductive core by an electroplating process. In some embodiments, the material of the conductive core is copper. In other embodiments, the material of the conductive core can be a tin alloy or other types of conductive materials.
[0040] In some embodiments, the material of the conductive coating portion is a tin alloy. Exemplarily, the material of the conductive coating portion is Sn64Pb37 or SnIn or SnBi or other tin alloy materials. In other embodiments, the conductive coating portion can be omitted, and the conductive core is welded to the front conductive pad 221.
[0041] Furthermore, in some embodiments, the material of the conductive coating portion and the material of the front conductive pad 221 belong to the same system of tin alloy, that is, the material of the conductive coating portion and the material of the front conductive pad 221 have the same alloy system. Furthermore, in some embodiments, the material of the front conductive pad 221 is the same as the material of the conductive coating portion.
[0042] On the surfaces of photovoltaic cells with different technologies, due to different process temperature requirements, high-temperature tin alloys or low-temperature tin alloys can be used. The conductive core is connected to the front conductive pad 221 through the conductive coating portion, and the two are connected by corresponding heating methods, which is beneficial to reducing the requirements for welding equipment and welding processes. At the same time, the material of the conductive coating portion is the same as or similar to the material of the front conductive pad 221. After heating to achieve tin-tin homogeneous melting connection, it is beneficial to further improve the connection stability between the conductive metal solder strip 20 and the front conductive pad 221.
[0043] Exemplarily, in some embodiments, the photovoltaic cell body 1 is a Perc photovoltaic cell. When the front fine grid line 21 is formed, the silver paste burns through the SiN covering layer on the front of the cell body 1 and is electrically connected to the emitter to export carriers. The front conductive pad 221 is directly welded and fixed to the surface of the SiN covering layer on the front of the photovoltaic cell 1 through an ultrasonic welding process. The materials of both the front conductive pad 221 and the conductive coating portion are PbSn high-temperature tin alloys.
[0044] Exemplarily, in some embodiments, the photovoltaic cell body 1 is a heterojunction HJT photovoltaic cell, and both the front and back of the heterojunction HJT photovoltaic cell are covered by TCO transparent conductive oxides. When the front fine grid line 21 is formed, the low-temperature silver paste used for forming the front fine grid line 21 is electrically connected to the TCO transparent conductive oxide covering layer on the front of the cell body 1 to export carriers. The materials of both the front conductive pad 221 and the conductive coating portion are SnBi low-temperature tin alloys.
[0045] In some other embodiments, the photovoltaic cell body 1 can also be other types of photovoltaic cells, and the materials of the front conductive pads 221 and the conductive coating portion should be adaptively adjusted according to the characteristics of the photovoltaic cell body 1.
[0046] The content of the soldering flux in the front conductive pads 221 and the conductive coating portion is zero, that is, neither the front conductive pads 221 nor the conductive coating portion contains soldering flux and no soldering flux is added during the welding process. The front conductive pads 221 can be welded to the cell body 1 through the ultrasonic welding process. At the same time, it is convenient to weld the conductive metal solder tape 20 to the front conductive pads 221 through the ultrasonic welding process, which is beneficial to improving the convenience and stability of the welding operation and reducing the welding cost. The soldering flux includes materials for assisting welding such as rosin resin and soldering paste.
[0047] Refer to Figure 3 , in some embodiments, all the front conductive pads 221 in the front pad group 22 are arranged at intervals. Specifically, in some embodiments, the front conductive pads 221 are in the shape of dots. In some other embodiments, the front conductive pads 221 are in the shape of long strips. The spaced arrangement of the front conductive pads 221 is beneficial to reducing the number of the front conductive pads 221 to reduce costs, and at the same time is convenient for releasing the stress generated when the front conductive pads 221 are welded to the cell body 1 to reduce the risk of the photovoltaic cell body 1 being broken. In some other embodiments, all the front conductive pads 221 in the same group are connected end to end to form a whole.
[0048] Refer to Figure 3 , in some embodiments, any one of the front conductive pads 221 in the front pad group 22 and any one of the front conductive pads 221 in an adjacent front pad group 22 are arranged staggeredly in the second direction Y, that is, the corresponding two front conductive pads 221 are not on the same straight line parallel to the second direction Y. The staggered arrangement of the front conductive pads 221 in two adjacent front pad groups 22 further facilitates the release of the stress generated when the front conductive pads 221 are welded to the cell body 1, and is beneficial to reducing the deformation of the photovoltaic cell body 1 caused by the thermal deformation of the conductive metal solder tape 20 after welding, so as to further reduce the risk of the photovoltaic cell body 1 being broken.
[0049] Refer to Figure 4 , in some embodiments, the second electrode 3 includes a plurality of back fine grid lines 31 and a plurality of back pad groups 32. The plurality of back fine grid lines 31 are arranged at intervals in sequence along the first direction X and are fixedly connected to the back of the cell body 1 and are electrically connected to the back of the cell body 1.
[0050] A plurality of back pad groups 32 are arranged at intervals in sequence along the second direction Y. The back pad group 32 includes a plurality of back conductive pads 321, and all the back conductive pads 321 in each back pad group 32 are arranged in sequence along the first direction X, and each back conductive pad 321 is welded to the back of the cell body 1. It can be understood that the second part 202 of the conductive metal solder strip 20 is welded to the back conductive pad 321.
[0051] In some embodiments, the back fine grid lines 31 are formed by screen printing aluminum paste. In other embodiments, the material of the back fine grid lines 31 is silver or other conductive materials.
[0052] Referring to Figure 5 , in some embodiments, the second electrode 3 includes a conductive metal film layer 33 and a plurality of back pad groups 32. The conductive metal film layer 33 is integrally formed on the back of the cell body 1 and is electrically connected to the back of the cell body 1. In some embodiments, the conductive metal film layer 33 is an aluminum film. Figure 5 The structure and distribution manner of the back pad group 32 in the provided embodiments are the same as those of Figure 4 the back pad group 32 in the provided embodiments. It can be understood that Figure 5 the back conductive pad 321 in the provided embodiments is welded to the conductive metal film layer 33.
[0053] For the 0BB main-grid-free tin alloy pad photovoltaic cell 10 provided in the present application, the conductive metal solder strip 20 is fixedly connected to the cell body 1 through the front conductive pad 221, which is beneficial to improving the connection stability between the conductive metal solder strip 20 and the cell body 1, thereby improving the electrical connection stability between the conductive metal solder strip 20 and the front fine grid lines 21. At the same time, by using the conductive metal solder strip 20 to replace the main grid lines on the front of the cell body 1, the silver paste required for making the main grid lines can be saved, and the production cost of the cell can be reduced.
[0054] The embodiments of the specific implementation manners are all preferred embodiments of the present application, and do not limit the protection scope of the present application accordingly. The same components are denoted by the same reference numerals. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application shall be covered within the protection scope of the present application.
Claims
1. A 0BB lead-free tin alloy pad photovoltaic cell, comprising a cell body (1), a first electrode (2) and a second electrode (3), wherein the first electrode (2) is disposed on the front surface of the cell body (1), and the second electrode (3) is disposed on the back surface of the cell body (1) and connected to the back surface of the cell body (1); characterized in that: The first electrode (2) includes: a plurality of front fine grid lines (21) which are sequentially arranged at intervals along the first direction (X) and are all connected to the front of the photovoltaic cell body (1); and a plurality of front pad groups (22) which are sequentially arranged at intervals along the second direction (Y), the front pad group (22) includes a plurality of front conductive pads (221), all the front conductive pads (221) in each front pad group (22) are sequentially arranged along the first direction (X), and each front conductive pad (221) is welded to the front of the cell body (1), and the second direction (Y) intersects with the first direction (X); The front conductive pad (221) and the second electrode (3) are configured to be respectively electrically connected to a conductive metal strip (20) for connecting the cell bodies (1) in series.
2. The 0BB main-gridless tin alloy pad photovoltaic cell according to claim 1, wherein: All the front conductive pads (221) in the front pad group (22) are arranged at intervals.
3. The 0BB main-gridless tin alloy pad photovoltaic cell according to claim 2, characterized in that: Any one of the front conductive pads (221) in the front pad group (22) is arranged staggeredly in the second direction (Y) with any one of the front conductive pads (221) in an adjacent front pad group (22).
4. The 0BB main-gridless tin alloy pad photovoltaic cell according to claim 1, characterized in that: All the front conductive pads (221) in the front pad group (22) are connected end to end in sequence.
5. The 0BB main-gridless tin alloy pad photovoltaic cell according to claim 1, wherein: The second electrode (3) includes: a plurality of back fine grid lines (31) which are sequentially arranged at intervals along the first direction (X) and are all connected to the back of the photovoltaic cell body (1); and a plurality of back pad groups (32) which are sequentially arranged at intervals along the second direction (Y), the back pad group (32) includes a plurality of back conductive pads (321), all the back conductive pads (321) in each back pad group (32) are sequentially arranged along the first direction (X), and each back conductive pad (321) is welded to the back of the cell body (1); The back conductive pad (321) is configured to be welded to a conductive metal strip (20) for connecting the cell bodies (1) in series.
6. The 0BB main-gridless tin alloy pad photovoltaic cell according to claim 1, wherein: The second electrode (3) includes: a conductive metal film layer (33) which is connected to the back of the cell body (1); and a plurality of back pad groups (32) which are sequentially arranged at intervals along the second direction (Y), the back pad group (32) includes a plurality of back conductive pads (321), all the back conductive pads (321) in each back pad group (32) are sequentially arranged along the first direction (X), and each back conductive pad (321) is welded to the conductive metal film layer (33); The back conductive pad (321) is configured to be welded to a conductive metal strip (20) for connecting the cell bodies (1) in series.
7. A photovoltaic cell string, characterized in that: It includes a plurality of conductive metal solder tapes (20) and a plurality of 0BB non-main-grid tin alloy pad photovoltaic cells (10) as described in any one of claims 1 to 6. The conductive metal solder tape (20) includes a first part (201), a second part (202) and a connecting part (203). The two ends of the connecting part (203) are respectively connected to the first part (201) and the second part (202). The first part (201) is welded to the front conductive pad (221) and electrically connected to a plurality of front fine grid lines (21). The second part (202) is electrically connected to the second electrode (3) of another cell body (1).
8. The photovoltaic cell string according to claim 7, characterized in that: The conductive metal solder tape (20) includes a conductive core part and a conductive coating part electrically connected to the conductive core part. The conductive coating part is welded to the front conductive pad (221) or electrically connected to the second electrode (3).
9. The photovoltaic cell string according to claim 8, wherein: The materials of the front conductive pad (221) and the conductive coating part of the conductive metal solder tape (20) are both tin alloy.
10. The photovoltaic cell string according to claim 8, wherein: The content of the soldering flux in the front conductive pad (221) and the conductive coating part of the conductive metal solder tape (20) is zero.