Back contact cell, back contact laminated cell and photovoltaic module

Abstract

The invention relates to the field of photovoltaic technology, and provides a back contact cell, a back contact laminated cell and a photovoltaic module, the back contact cell comprises a body and a main grid, the main grid comprises a copper layer and a tin layer, the copper layer is arranged on the backlight surface of the body, and the tin layer coats the outer surface of the copper layer; in the length direction of the main grid, the main grid is provided with main body parts and connecting parts which are alternately distributed, and the connecting parts are higher than the main body parts. When the main grid and the welding strip are welded, the tin layer can be directly used as welding flux to achieve welding and fixing of the main grid and the welding strip, solder paste does not need to be independently printed on the main grid, the steps of the welding process are simplified, the efficiency of the welding process is improved, and therefore the production efficiency of the photovoltaic module is improved. When the main grid is welded with the welding strip, the connecting part can be in good contact with the welding strip so as to reduce the risk of pseudo soldering or missing soldering, that is, the connecting part can be used as a bonding pad to be welded and fixed with the welding strip so as to improve the welding reliability of the main grid and the welding strip.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, specifically to a back-contact battery, a back-contact tandem battery, and a photovoltaic module. Background Technology

[0002] In back-contact solar cells, both the positive and negative grid lines are located on the back side, leaving the light-facing side unobstructed by the grid lines. Compared to conventional photovoltaic cells, this reduces light energy loss due to grid line shading and results in higher photoelectric conversion efficiency. When multiple back-contact solar cells are assembled into a photovoltaic module, electrical connections between adjacent cells are typically achieved using solder ribbons. The two ends of the solder ribbons are welded and fixed to the main grids of the two adjacent cells, respectively.

[0003] Existing back-contact cells require solder paste to be printed or applied to the main grid before being soldered to the solder strip. The solder paste is used to fix the solder strip to the main grid. The soldering process is relatively complicated, resulting in low production efficiency of photovoltaic modules. Summary of the Invention

[0004] In view of this, this application provides a back contact cell, a back contact tandem cell, and a photovoltaic module to solve the problem that the welding steps between the back contact cell and the solder strip in the prior art are relatively cumbersome, resulting in low production efficiency of the photovoltaic module.

[0005] In a first aspect, embodiments of this application provide a back contact battery, comprising: a body; a main grid, including a copper layer and a tin layer, wherein the copper layer is disposed on the back surface of the body, and the tin layer covers the outer surface of the copper layer; along the length direction of the main grid, the main grid has alternating main body portions and connecting portions, wherein the height of the connecting portions is greater than the height of the main body portions.

[0006] In one possible implementation, the length L of the connecting portion along the length direction of the main gate satisfies: 0.8mm ≤ L ≤ 1.2mm.

[0007] In one possible implementation, the copper layer includes a first copper layer segment located in the main body and a second copper layer segment located in the connecting portion, wherein the height H1 of the first copper layer segment is equal to the height H2 of the second copper layer segment; the tin layer includes a first tin layer segment located in the main body and a second tin layer segment located in the connecting portion, wherein the height H3 of the first tin layer segment is less than the height H4 of the second tin layer segment.

[0008] In one possible implementation, the height H1 of the first copper layer and the height H2 of the second copper layer satisfy: 5μm≤H1=H2≤12μm; the height H3 of the first tin layer satisfies: 0.5μm≤H3≤2μm; and the height H4 of the second tin layer satisfies: 12μm≤H4≤13μm.

[0009] In one possible implementation, the copper layer includes a first copper layer segment located in the main body and a second copper layer segment located in the connecting portion, wherein the height H1 of the first copper layer segment is less than the height H2 of the second copper layer segment; the tin layer includes a first tin layer segment located in the main body and a second tin layer segment located in the connecting portion, wherein the height H3 of the first tin layer segment is less than the height H4 of the second tin layer segment.

[0010] In one possible implementation, the height H1 of the first copper layer segment satisfies: 5μm≤H1≤12μm; the height H2 of the second copper layer segment satisfies: 15μm≤H2≤22μm; the height H3 of the first tin layer segment satisfies: 0.5μm≤H3≤2μm; and the height H4 of the second tin layer segment satisfies: 2μm≤H4≤3μm.

[0011] In one possible implementation, the back contact battery further includes a fine grid and an insulating member. The fine grid is disposed on the back surface of the body, and the fine grid includes a first fine grid and a second fine grid that are alternately distributed along the length direction of the main grid. The first fine grid is connected to the main grid, and the second fine grid is spaced apart from the main grid. At least a portion of the insulating member covers the end of the second fine grid near the main grid, so that the second fine grid is insulated from the main grid.

[0012] In one possible implementation, the height H5 of the insulating member and the height H6 of the connecting portion satisfy: -5μm≤H6-H5≤15μm.

[0013] Secondly, embodiments of this application provide a back-contact stacked solar cell, including a back-contact bottom cell and a perovskite top cell, wherein the perovskite top cell and the light-facing surface of the back-contact bottom cell are electrically connected; the back-contact bottom cell includes: a body; a main grid, including a copper layer and a tin layer, wherein the copper layer is disposed on the back-facing surface of the body, and the tin layer covers the outer surface of the copper layer; along the length direction of the main grid, the main grid has alternating main body portions and connecting portions, wherein the height of the connecting portions is greater than the height of the main body portions.

[0014] Thirdly, embodiments of this application provide a photovoltaic module, including: a battery string, comprising a solder ribbon and a plurality of photovoltaic cells, two adjacent photovoltaic cells being connected by the solder ribbon, wherein the photovoltaic cells are back-contact cells as described above, or the photovoltaic cells are back-contact stacked cells as described above, and the solder ribbon is welded and fixed to the connecting portion; an encapsulation layer for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulation layer away from the battery string.

[0015] In one possible implementation, the yield strength of the weld strip is 45 MPa to 65 MPa.

[0016] The beneficial effects of this application are as follows: The main grid adopts a tin-clad copper structure. The copper layer has good conductivity, which helps to reduce the resistance of the main grid and reduce current transmission loss. Moreover, copper has good mechanical strength, making the main grid less prone to breakage or damage, thus improving its reliability. In addition, copper is relatively inexpensive, which helps to reduce the manufacturing cost of the main grid, thereby reducing the production cost of the back contact cells. The tin layer has good corrosion resistance. When it coats the outer surface of the copper layer, it can form a dense oxide film in the air, acting as a protective film on the surface of the copper layer, isolating it from the external humid or corrosive environment, preventing oxidation or corrosion, and thus extending the service life of the main grid. On the other hand, when the main grid is soldered to the solder strip, the tin layer can be directly used as solder to fix the main grid to the solder strip, eliminating the need to print solder paste separately on the main grid. This simplifies the soldering process and improves the efficiency of the soldering process, thereby increasing the production efficiency of photovoltaic modules.

[0017] When welding the main grid to the solder strip, the connecting part can form good contact with the solder strip to reduce the risk of poor soldering or open solder joints. In other words, the connecting part can act as a solder pad to fix the solder strip, improving the welding reliability of the main grid and solder strip. When multiple connecting parts are spaced apart along the length of the main grid, they can provide stable support for the solder strip, resulting in more uniform stress on the solder strip during welding. This helps reduce the risk of solder strip deformation and the stress applied by the solder strip to the main grid, reducing the risk of main grid breakage, thereby improving the structural reliability of the back contact battery. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a partial structural diagram of the back surface of the back contact battery provided in an embodiment of this application; Figure 2 for Figure 1 A cross-sectional view of the back contact battery in the first embodiment; Figure 3 for Figure 2 An enlarged view of part A in the image; Figure 4 for Figure 1 A cross-sectional view of the back contact battery in the second embodiment; Figure 5 for Figure 4An enlarged view of part B in the image; Figure 6 for Figure 1 A schematic cross-sectional view of the back contact battery in the first embodiment along another direction; Figure 7 for Figure 1 A schematic diagram of another cross-sectional structure of the back contact battery in the first embodiment along another direction. Figure 8 This is a schematic diagram of the back surface of the back contact battery provided in an embodiment of this application; Figure 9 This is a schematic diagram of the structure of the back contact stacked battery provided in the embodiments of this application; Figure 10 This is a schematic diagram of the structure of the photovoltaic module provided in the first embodiment of this application; Figure 11 This is a schematic diagram of the structure of the photovoltaic module provided in the second embodiment of this application.

[0020] Figure label: 10-Back contact battery; 20-Back contact stacked battery; 201-Back contact bottom battery; 202-Perovskite Top Cell; 30 - Welding strip; 40 - Encapsulation layer; 50 - Cover plate; 1-Ontology; 2-Main gate; 2a-Main body; 2b - Connecting part; 21-Copper layer; 211 - First copper layer segment; 212 - Second copper layer segment; 22-Tin layer; 221 - First tin layer segment; 222 - Second tin layer segment; 23 - First main gate; 24 - Second main gate; 3-Fine grid; 31 - First fine grid; 31' - First positive electrode fine grid; 31" - First negative electrode fine grid; 32 - Second fine grid; 32' - Second positive electrode fine gate; 32" - Second negative electrode fine grid; 4-Insulating components; 5-Edge grid lines. Detailed Implementation

[0021] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0022] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0023] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0024] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0025] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0026] This application provides a back contact battery 10, such as Figure 1 As shown, the back contact battery 10 includes a body 1, and a main grid 2 is provided on the back surface of the body 1. The main grid 2 is used for welding and fixing to the solder strip. The main grid 2 can form an electrical connection with the solder strip to realize the series connection between adjacent back contact batteries 10, and the main grid 2 can cooperate with the solder strip to conduct the photocurrent generated in the body 1 outward. Figure 2As shown, the main gate 2 includes a copper layer 21 and a tin layer 22. The copper layer 21 is disposed on the back surface of the body 1, and the tin layer 22 covers the outer surface of the copper layer 21. That is, the main gate 2 adopts a tin-clad copper structure. The copper layer 21 has good conductivity, which helps to reduce the resistance of the main gate 2 and reduce current transmission loss. Moreover, copper material has good mechanical strength, making the main gate 2 less prone to breakage or damage, which helps to improve the reliability of the main gate 2. In addition, the low price of copper material helps to reduce the manufacturing cost of the main gate 2, thereby reducing the production cost of the back contact battery 10. The tin layer 22 has good corrosion resistance. When it covers the outer surface of the copper layer 21, it can form a dense oxide film in the air, which acts as a protective film on the surface of the copper layer 21, isolating the copper layer 21 from the external humid or corrosive environment, preventing the copper layer 21 from being oxidized or corroded, thereby helping to extend the service life of the main gate 2. On the other hand, when the main busbar 2 is welded to the solder strip, the tin layer 22 can be directly used as solder to fix the main busbar 2 to the solder strip. There is no need to print solder paste separately on the main busbar 2, which simplifies the welding process and helps to improve the efficiency of the welding process, thereby improving the production efficiency of photovoltaic modules.

[0027] The copper layer 21 and the tin layer 22 can be made by electroplating. The tin layer 22 made by electroplating can fully cover the top surface and sidewalls of the copper layer 21, reducing the risk of the copper layer 21 being oxidized due to exposure to air.

[0028] Furthermore, along the length Y of the main grid 2, the main grid 2 has alternating main body portions 2a and connecting portions 2b, with the height of the connecting portions 2b being greater than the height of the main body portions 2a. When the main grid 2 is welded to the solder strip, the heightened connecting portions 2b can form good contact with the solder strip, reducing the risk of poor soldering or open soldering. That is, the connecting portions 2b can act as solder pads to fix the main grid 2 to the solder strip, thereby improving the welding reliability between the main grid 2 and the solder strip. When multiple connecting portions 2b are spaced apart along the length Y of the main grid 2, the connecting portions 2b can provide stable support for the solder strip, making the stress on the solder strip more uniform during welding. This helps reduce the risk of solder strip deformation and also helps reduce the stress applied by the solder strip to the main grid 2, reducing the risk of main grid 2 breakage, thereby improving the structural reliability of the back contact battery 10.

[0029] In some embodiments, the length L of the connecting portion 2b along the length Y of the main grid 2 satisfies: 0.8mm ≤ L ≤ 1.2mm. When L meets this range, the contact area between the connecting portion 2b and the solder strip can be increased, thereby improving the welding reliability between the main grid 2 and the solder strip, reducing the risk of solder strip detachment, which is beneficial to improving the service life of the photovoltaic module. It also helps to reduce the lateral resistance of the main grid 2, thereby improving the current collection efficiency. Moreover, when L meets this range, the amount of raw materials used in the main grid 2 can also be reduced, thereby reducing the production cost of the back contact cell 10.

[0030] Optionally, the length L of the connecting part 2b satisfies: 0.8mm≤L≤1mm. L can be 0.8mm, 0.81mm, 0.82mm, 0.83mm, 0.84mm, 0.85mm, 0.86mm, 0.87mm, 0.88mm, 0.89mm, 0.9mm, 0.91mm, 0.92mm, 0.93mm, 0.94mm, 0.95mm, 0.96mm, 0.97mm, 0.98mm, 0.99mm or 1mm, or other values ​​within the above range. This application embodiment does not limit this.

[0031] Optionally, the length L of the connecting part 2b satisfies: 1mm≤L≤1.2mm. L can be 1mm, 1.01mm, 1.02mm, 1.03mm, 1.04mm, 1.05mm, 1.06mm, 1.07mm, 1.08mm, 1.09mm, 1.1mm, 1.11mm, 1.12mm, 1.13mm, 1.14mm, 1.15mm, 1.16mm, 1.17mm, 1.18mm, 1.19mm, or 1.2mm, or other values ​​within the above range. This application embodiment does not limit this.

[0032] In some embodiments, the width of the connecting portion 2b can be greater than the width of the main body portion 2a, which makes it easier for the solder strip to make contact with the connecting portion 2b, thereby reducing the risk of incomplete or empty soldering due to solder strip misalignment and improving the welding reliability between the main grid 2 and the solder strip.

[0033] This application provides two specific embodiments of the structure of the main gate 2, such as... Figure 2 and Figure 3 As shown, in a first specific embodiment, the copper layer 21 includes a first copper layer segment 211 located in the main body 2a and a second copper layer segment 212 located in the connecting portion 2b. The height H1 of the first copper layer segment 211 is equal to the height H2 of the second copper layer segment 212. The tin layer 22 includes a first tin layer segment 221 located in the main body 2a and a second tin layer segment 222 located in the connecting portion 2b. The height H3 of the first tin layer segment 221 is less than the height H4 of the second tin layer segment 222. That is, the copper layers 21 of the main gate 2 are of equal height, and the connecting portion 2b is formed only by locally increasing the height of the tin layer 22.

[0034] In this embodiment, the height H1 of the first copper layer segment 211 is equal to the height H2 of the second copper layer segment 212, so that the cross-sectional area of ​​the copper layer 21 in the length direction Y of the main gate 2 is uniform. This improves the uniformity of current transmission in the length direction Y of the main gate 2, thereby improving the output power of the back contact battery 10. The second tin layer segment 222 with a larger height and the corresponding second copper layer segment 212 together constitute the connecting portion 2b. The connecting portion 2b formed by increasing the height of the second tin layer segment 222 can provide more solder when the main gate 2 is soldered to the solder strip, thereby further improving the soldering reliability of the main gate 2 and the solder strip.

[0035] Specifically, when fabricating the main gate 2, a copper layer 21 with a height of H1 can be prepared first by electroplating, and then a tin layer 22 with a height of H3 can be prepared on the outer surface of the copper layer 21 by electroplating. Finally, another tin layer 22 with a height of H4-H3 can be electroplated again in a preset area on the top surface of the tin layer 22, so that the tin layer 22 can form a first tin layer segment 221 and a second tin layer segment 222 with different heights.

[0036] In this embodiment, the height H1 of the first copper layer segment 211 and the height H2 of the second copper layer segment 212 satisfy the following condition: 5μm ≤ H1 = H2 ≤ 12μm. That is, the height of the copper layer 21 is 5μm to 12μm. When this range is met, the copper layer 21 can be guaranteed to have good structural strength, which is beneficial to improving the structural strength of the main gate 2 and reducing the risk of breakage when the main gate 2 is subjected to pressure or bending, thereby helping to extend the service life of the back contact battery 10. At the same time, it can also ensure that the copper layer 21 has good conductivity, reducing the resistance of the main gate 2, which is beneficial to improving the output power of the back contact battery 10.

[0037] Optionally, the height H1 of the first copper layer segment 211 and the height H2 of the second copper layer segment 212 satisfy: 5μm≤H1=H2≤8μm. H1 and H2 can be 5μm, 5.2μm, 5.4μm, 5.6μm, 5.8μm, 6μm, 6.2μm, 6.4μm, 6.6μm, 6.8μm, 7μm, 7.2μm, 7.4μm, 7.6μm, 7.8μm or 8μm, or other values ​​within the above range. This embodiment does not limit this.

[0038] Optionally, the height H1 of the first copper layer segment 211 and the height H2 of the second copper layer segment 212 satisfy: 8μm≤H1=H2≤12μm. H1 and H2 can be 8μm, 8.2μm, 8.4μm, 8.6μm, 8.8μm, 9μm, 9.2μm, 9.4μm, 9.6μm, 9.8μm, 10μm, 10.2μm, 10.4μm, 10.6μm, 10.8μm, 11μm, 11.2μm, 11.4μm, 11.6μm, 11.8μm or 12μm, or other values ​​within the above range. This embodiment does not limit this value.

[0039] In this embodiment, the height H3 of the first tin layer segment 221 satisfies: 0.5μm≤H3≤2μm. When H3 meets this range, it ensures that the first tin layer segment 221 can meet the anti-oxidation and anti-corrosion requirements of the copper layer 21, and can also appropriately reduce the amount of raw materials used in the first tin layer segment 221, thereby reducing the total cost of the tin layer 22.

[0040] Optionally, the height H3 of the first tin layer segment 221 can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm or 2μm, or other values ​​within the above range. This embodiment does not limit this value.

[0041] In this embodiment, the height H4 of the second tin layer segment 222 satisfies: 12μm≤H4≤13μm. When H4 meets this range, it ensures that the second tin layer segment 222 can provide sufficient solder when the connection part 2b is soldered to the solder strip, and can also appropriately reduce the amount of raw materials used in the second tin layer segment 222, thereby reducing the total cost of the tin layer 22.

[0042] Optionally, the height H4 of the second tin layer segment 222 can be 12μm, 12.1μm, 12.2μm, 12.3μm, 12.4μm, 12.5μm, 12.6μm, 12.7μm, 12.8μm, 12.9μm or 13μm, or other values ​​within the above range. This embodiment does not limit this value.

[0043] like Figure 2 and Figure 3As shown, in the second specific embodiment, the copper layer 21 includes a first copper layer segment 211 located in the main body 2a and a second copper layer segment 212 located in the connecting portion 2b, wherein the height H1 of the first copper layer segment 211 is less than the height H2 of the second copper layer segment 212. The tin layer 22 includes a first tin layer segment 221 located in the main body 2a and a second tin layer segment 222 located in the connecting portion 2b, wherein the height H3 of the first tin layer segment 221 is less than the height H4 of the second tin layer segment 222. That is, the main gate 2 forms the connecting portion 2b by partially raising the copper layer 21 and the tin layer 22 respectively.

[0044] In this embodiment, since tin is more expensive than copper, with the total height of the connection portion 2b fixed, setting the height H1 of the first copper layer segment 211 to be less than the height H2 of the second copper layer segment 212 reduces the height H4 of the second tin layer segment 222, thus reducing the amount of raw material used in the second tin layer segment 222 and lowering the total cost of the main gate 2. Furthermore, increasing the height of the second copper layer segment 212 relative to the first copper layer segment 211 increases its cross-sectional area, thereby reducing its resistance and improving the current transmission efficiency between the connection portion 2b and the solder strip. The second copper layer segment 212 and the corresponding second tin layer segment 222 together constitute the connection portion 2b. Increasing the height of the second tin layer segment 222 relative to the first tin layer segment 221 provides more solder during the welding of the main gate 2 and the solder strip, further improving the welding reliability of the main gate 2 and the solder strip.

[0045] Specifically, when fabricating the main gate 2, a portion of copper layer 21 with a height of H1 can be prepared first by electroplating. Then, another portion of copper layer 21 with a height of H2-H1 is electroplated a second time in a predetermined area on the top surface of this portion of copper layer 21, thereby forming a first copper layer segment 211 and a second copper layer segment 212 with different heights. Next, a portion of tin layer 22 with a height of H3 is prepared on the outer surface of the copper layer 21 by electroplating. Finally, another portion of tin layer 22 with a height of H4-H3 is electroplated a second time in a predetermined area on the top surface of this portion of tin layer 22 (the area corresponding to the second copper layer segment 212), thereby forming a first tin layer segment 221 and a second tin layer segment 222 with different heights.

[0046] In this embodiment, the height H1 of the first copper layer segment 211 satisfies: 5μm≤H1≤12μm. Meeting this range ensures that the first copper layer segment 211 has good structural strength, which is beneficial for improving the structural strength of the main gate 2 and reducing the risk of breakage when the main gate 2 is subjected to pressure or bending, thereby extending the service life of the back contact battery 10. Simultaneously, it also ensures that the copper layer 21 has good conductivity, reducing the resistance of the main gate 2 and thus improving the output power of the back contact battery 10.

[0047] Optionally, the height H1 of the first copper layer segment 211 satisfies: 5μm≤H1≤8μm. H1 can be 5μm, 5.2μm, 5.4μm, 5.6μm, 5.8μm, 6μm, 6.2μm, 6.4μm, 6.6μm, 6.8μm, 7μm, 7.2μm, 7.4μm, 7.6μm, 7.8μm or 8μm, or other values ​​within the above range. This embodiment does not limit this value.

[0048] Optionally, the height H1 of the first copper layer segment 211 satisfies: 8μm≤H1≤12μm. H1 can be 8μm, 8.2μm, 8.4μm, 8.6μm, 8.8μm, 9μm, 9.2μm, 9.4μm, 9.6μm, 9.8μm, 10μm, 10.2μm, 10.4μm, 10.6μm, 10.8μm, 11μm, 11.2μm, 11.4μm, 11.6μm, 11.8μm, or 12μm, or other values ​​within the above range. This embodiment does not limit this value.

[0049] In this embodiment, the height H2 of the second copper layer segment 212 satisfies: 15μm≤H2≤22μm. When H2 meets this range, by reasonably increasing the height H2 of the second copper layer segment 212, the height H4 of the second tin layer segment 222 is appropriately reduced, that is, the amount of raw material used in the second tin layer segment 222 is further reduced, thereby further reducing the total cost of the main gate 2. Moreover, when H2 meets this range, it can ensure that the cross-sectional area of ​​the second copper layer segment 212 is appropriate, which is conducive to further reducing the resistance of the second copper layer segment 212, thereby further improving the current transmission efficiency between the connection part 2b and the solder strip.

[0050] In this embodiment, the height H3 of the first tin layer segment 221 satisfies: 0.5μm≤H3≤2μm. When H3 meets this range, it ensures that the first tin layer segment 221 can meet the anti-oxidation and anti-corrosion requirements of the copper layer 21, and can also appropriately reduce the amount of raw materials used in the first tin layer segment 221, thereby reducing the total cost of the tin layer 22.

[0051] Optionally, the height H3 of the first tin layer segment 221 can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm or 2μm, or other values ​​within the above range. This embodiment does not limit this value.

[0052] In this embodiment, the height H4 of the second tin layer segment 222 satisfies: 2μm≤H4≤3μm. When H4 satisfies this range, it ensures that the second tin layer segment 222 can provide sufficient solder when the connection part 2b is soldered to the solder strip, and can further reduce the amount of raw materials used in the second tin layer segment 222, thereby further reducing the total cost of the tin layer 22.

[0053] Optionally, the height H4 of the second tin layer segment 222 can be 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm or 3μm, or other values ​​within the above range. This embodiment does not limit this value.

[0054] In some embodiments, such as Figure 1 and Figure 6 As shown, the back contact battery 10 also includes a fine grid 3, which is disposed on the back surface of the body 1. The fine grid 3 includes a first fine grid 31 and a second fine grid 32 alternately distributed along the length direction Y of the main grid 2. Both the first fine grid 31 and the second fine grid 32 extend along the width direction X of the main grid 2, and are used to collect and guide the photocurrent generated in the body 1. The first fine grid 31 and the second fine grid 32 have opposite polarities, one of which is the positive electrode fine grid of the back contact battery 10, and the other is the negative electrode fine grid of the back contact battery 10. The first fine grid 31 has the same polarity as the main grid 2. The first fine grid 31 is connected to the main grid 2 to form an electrical connection, so that the main grid 2 can collect the photocurrent collected by the first fine grid 31 and output it outward through the connecting part 2b and the solder strip. The second fine grid 32 has the opposite polarity to the main grid 2. The second fine grid 32 is spaced apart from the main grid 2, that is, the second fine grid 32 is disconnected at the main grid 2 to avoid the second fine grid 32 being electrically connected to the main grid 2 and short-circuiting.

[0055] It should be noted that the accompanying drawings provided in this application use lines of different thicknesses to distinguish the first fine gate 31 and the second fine gate 32. This is not a limitation on the relative width between the first fine gate 31 and the second fine gate 32. The width of the first fine gate 31 and the width of the second fine gate 32 may be equal or unequal.

[0056] Among them, the fine gate 3 can also be a tin-clad copper structure manufactured by electroplating. The tin layer 22 of the main gate 2 and the tin layer of the fine gate 3 can be prepared in one step by electroplating, such as... Figure 1 As shown, the tin layer of the first fine gate 31 and the tin layer 22 of the main gate 2 can be an integral structure to ensure that the copper material at the connection between the first fine gate 31 and the main gate 2 is not corroded or oxidized by the outside.

[0057] In some embodiments, the back surface of the back contact battery 10 is further provided with an insulating member 4, such as... Figure 1As shown, the insulating member 4 extends along the width direction X of the main gate 2. At least a portion of the insulating member 4 covers the end of the second fine gate 32 near the main gate 2, so that the second fine gate 32 with opposite polarity is insulated from the main gate 2. This also prevents the same solder strip from being electrically connected to both the second fine gate 32 with opposite polarity and the main gate 2 simultaneously, thus avoiding a short circuit. This embodiment uses insulating adhesive as an example to illustrate the insulating member 4.

[0058] The height H5 of the insulating component 4 and the height H6 of the connecting part 2b satisfy the following condition: -5μm ≤ H6 - H5 ≤ 15μm. When H6 - H5 meets this range, the height of the connecting part 2b is appropriate, avoiding excessive bending during welding of the solder strip to the connecting part 2b, reducing the risk of solder strip damage. It also prevents the solder strip from being unable to contact the connecting part 2b due to the insulating component 4 being too low, thus reducing the risk of incomplete or missed welds. Conversely, it also prevents stress concentration when the connecting part 2b contacts the solder strip due to excessive height, further reducing the risk of solder strip damage.

[0059] Optionally, H5 and H6 satisfy: -5μm≤H6-H5≤5μm, where H6-H5 can be -5μm, -4.5μm, -4μm, -3.5μm, -3μm, -2.5μm, -2μm, -1.5μm, -1μm, -0.5μm, 0μm, 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, or 5μm, or other values ​​within the above range. This embodiment does not impose any restrictions on this.

[0060] Optionally, H5 and H6 satisfy: 5μm≤H6-H5≤15μm, where H6-H5 can be 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, 11.5μm, 12μm, 12.5μm, 13μm, 13.5μm, 14μm, 14.5μm, or 15μm, or other values ​​within the above range. This embodiment does not impose any restrictions on this.

[0061] In the embodiments of this application, such as Figure 6As shown, the main grid 2 includes a first main grid 23 and a second main grid 24 alternately distributed in the width direction X of the main grid 2. The first main grid 23 and the second main grid 24 have opposite polarities, one of which is the positive main grid of the back contact battery 10, and the other is the negative main grid of the back contact battery 10. In this embodiment of the application, the specific structure of the back contact battery 10 is described in detail with the first main grid 23 as the positive main grid and the second main grid 24 as the negative main grid as an example: the first fine grid 31 connected to the first main grid 23 is the first positive fine grid 31', and the second fine grid 32 disposed at intervals from the first main grid 23 is the second negative fine grid 32". The first positive fine grid 31' and the second negative fine grid 32" are alternately distributed in the length direction Y of the main grid 2. The first fine grid 31 connected to the second main grid 24 is the first negative electrode fine grid 31". The second fine grid 32, spaced apart from the second main grid 24, is the second positive electrode fine grid 32'. The first negative electrode fine grid 31" and the second positive electrode fine grid 32' are alternately distributed along the length direction Y of the main grid 2. Along the width direction X of the main grid 2, the first positive electrode fine grid 31' and the second positive electrode fine grid 32' are an integral structure, which can also be understood as the first positive electrode fine grid 31' and the second positive electrode fine grid 32' being two adjacent regions on the positive electrode fine grid. Along the first direction X, the second negative electrode fine grid 32" and the first negative electrode fine grid 31" are an integral structure, which can also be understood as the second negative electrode fine grid 32" and the first negative electrode fine grid 31" being two adjacent regions on the negative electrode fine grid.

[0062] When multiple back contact cells 10 are used to form a photovoltaic module, two adjacent back contact cells 10 are electrically connected by a solder strip. One end of the solder strip is welded to the connection portion 2b on the first main grid 23 of one of the back contact cells 10 to form an electrical connection, and the other end is welded to the connection portion 2b on the second main grid 24 of the other back contact cell 10 to form an electrical connection.

[0063] like Figure 8 As shown, the back contact battery 10 is further provided with edge grid lines 5 at both ends along the width direction X of the main grid 2, and the edge grid lines 5 extend along the length direction Y of the main grid 2. The polarity of the edge grid lines 5 is opposite to that of the adjacent main grid 2, and is used to form an electrical connection with the fine grids 3 that are interrupted by the main grid 2, so as to collect the current collected by the interrupted fine grids 3, thereby improving the efficiency of the back contact battery 10. The polarities of the two edge grid lines 5 located at both ends of the back contact battery 10 along the width direction X of the main grid 2 can be the same or opposite; this embodiment does not limit this.

[0064] In some embodiments, the back contact cell 10 can be one of the following: interdigitated back contact (IBC), heterojunction back contact (HBC), or tunnel oxide back contact (TBC). For an IBC cell, along its thickness direction, the IBC cell sequentially includes a silicon nitride inversion layer, an N+ front surface field, an N-type substrate silicon layer, a P+ emitter, an N+ back field, an aluminum oxide passivation layer, a silicon nitride antireflection layer, and a silver electrode. IBC cells utilize ion implantation technology to obtain P- and N-regions with good uniformity and precise controllable junction depth. The absence of grid lines on the front of the cell eliminates light-blocking current loss from metal electrodes, maximizing the utilization of incident photons and improving short-circuit current by approximately 7% compared to conventional solar cells. Due to the back-contact structure, grid line shading is not a concern, allowing for a wider grid line ratio, thus reducing series resistance and achieving a high fill factor. Optimized design of surface passivation and light-trapping structures can be achieved, resulting in lower front-surface recombination rates and surface reflections.

[0065] HBC cells effectively combine the advantages of IBC and heterojunction cells. Their front surface passivation layer uses hydrogenated amorphous silicon, while N-type and P-type amorphous silicon films are deposited on the back side to form a heterojunction. HBC cells fully utilize the superior surface passivation properties of amorphous silicon, and the heterojunction structure formed on the back side exhibits excellent passivation, enabling the simultaneous achievement of higher short-circuit current and open-circuit voltage, thereby improving photoelectric conversion efficiency.

[0066] For TBC cells, the advantages of Topcon's tunneling oxide layer technology and IBC back-side electrode arrangement are combined, resulting in significantly improved passivation and open-circuit voltage, achieving higher cell conversion efficiency while maintaining economic viability. The complete production process of TBC cells mainly includes depositing tunneling oxide and P+ polycrystalline silicon, depositing passivation films, and printing electrodes on the back of the silicon wafer. Based on the Topcon production process, TBC cells require additional back-side electrode processes such as masking, laser grooving, PN region fabrication, and etching. Masking is mainly done using APCVD or PECVD, PN region fabrication is mainly done using PECVD, etching mainly uses traditional wet processing equipment, and grooving is performed using laser equipment.

[0067] This application also provides a back-contact stacked battery 20, such as Figure 9As shown, the back-contact tandem solar cell 20 includes a back-contact bottom cell 201 and a perovskite top cell 202. The perovskite top cell 202 is electrically connected to the light-facing surface of the back-contact bottom cell 201. The back-contact bottom cell 201 can be the back-contact cell 10 described above, and the perovskite top cell 202 is a thin-film solar cell with perovskite material as the photoactive layer. The structure of the perovskite top cell 202 mainly consists of the following key components: a transparent conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode. These components work together to enable the perovskite top cell 202 to effectively absorb sunlight and convert it into electrical energy. The perovskite material in the perovskite light-absorbing layer has excellent light absorption performance, can absorb a wider spectral range, and effectively convert short-wavelength spectra, giving the perovskite top cell 202 high photoelectric conversion efficiency.

[0068] This application also provides a photovoltaic module, such as... Figure 10 and Figure 11 As shown, the photovoltaic module includes multiple photovoltaic cells and solder ribbons 30. The photovoltaic cells are either the back-contact cells 10 described above, or the back-contact tandem cells 20 described above. The main grids 2 of two adjacent photovoltaic cells along the length Y of the main grid 2 are connected by solder ribbons 30.

[0069] The photovoltaic module also includes an encapsulation layer 40 and a cover plate 50. The encapsulation layer 40 covers the light-facing and back-facing sides of the cell string, while the cover plate 50 covers the surface of the encapsulation layer 40 away from the cell string. During the lamination process of the photovoltaic module, the encapsulation layer 40 encapsulates and protects the photovoltaic cells and solder ribbons 30, preventing external environmental factors from affecting their performance. It also bonds the cover plate 50, photovoltaic cells, and solder ribbons 30 together as a single unit.

[0070] The cover plate 50 can be made of one of the following rigid materials: tempered glass, polyethylene terephthalate (PET), polycarbonate (PC); or one of the following flexible materials: polyvinyl fluoride (PVF), ethylene-tetrafluoroethylene copolymer (ETE), polyvinylidene fluoride (PVDF). The encapsulation layer 40 is an adhesive film, which can be made of one of the following materials: ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), polyvinyl butyral (PVB). The encapsulation layer 40 can also be an EPE film (EVA-POE-EVA co-extruded structure) or an EP film (EVA-POE co-extruded structure).

[0071] In some embodiments, the yield strength of the welding strip 30 is 45 MPa to 65 MPa. When the yield strength of the welding strip 30 meets the above range, the welding strip 30 is a low-yield welding strip. The low-yield welding strip can better adapt to the thermal expansion and contraction caused by temperature changes during the welding process, thereby reducing the risk of weld joint failure due to thermal stress. Moreover, the low-yield welding strip has greater flexibility, making the welding strip 30 less prone to breakage when subjected to external force, which can prevent the welded structure from cracking or detaching, thereby improving the welding reliability between the main grid 2 and the welding strip 30.

[0072] Optionally, the yield strength of the welding strip 30 is 45MPa, 46MPa, 47MPa, 48MPa, 49MPa, 50MPa, 51MPa, 52MPa, 53MPa, 54MPa, 55MPa, 56MPa, 57MPa, 58MPa, 59MPa, 60MPa, 61MPa, 62MPa, 63MPa, 64MPa or 65MPa, or other values ​​within the above range. This embodiment does not limit this value.

[0073] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A back-contact battery, characterized in that, include: Ontology(1); The main gate (2) includes a copper layer (21) and a tin layer (22). The copper layer (21) is disposed on the back surface of the body (1), and the tin layer (22) covers the outer surface of the copper layer (21). Along the length of the main grid (2), the main grid (2) has alternating main body portions (2a) and connecting portions (2b), the height of the connecting portions (2b) being greater than the height of the main body portions (2a).

2. The back contact battery according to claim 1, characterized in that, Along the length direction of the main gate (2), the length L of the connecting part (2b) satisfies: 0.8mm≤L≤1.2mm.

3. The back contact battery according to claim 1, characterized in that, The copper layer (21) includes a first copper layer segment (211) located in the main body (2a) and a second copper layer segment (212) located in the connecting part (2b), wherein the height H1 of the first copper layer segment (211) is equal to the height H2 of the second copper layer segment (212); The tin layer (22) includes a first tin layer segment (221) located in the main body (2a) and a second tin layer segment (222) located in the connecting part (2b), wherein the height H3 of the first tin layer segment (221) is less than the height H4 of the second tin layer segment (222).

4. The back contact battery according to claim 3, characterized in that, The height H1 of the first copper layer segment (211) and the height H2 of the second copper layer segment (212) satisfy: 5μm≤H1=H2≤12μm; The height H3 of the first tin layer segment (221) satisfies: 0.5μm≤H3≤2μm; The height H4 of the second tin layer segment (222) satisfies: 12μm≤H4≤13μm.

5. The back contact battery according to claim 1, characterized in that, The copper layer (21) includes a first copper layer segment (211) located in the main body (2a) and a second copper layer segment (212) located in the connecting part (2b), wherein the height H1 of the first copper layer segment (211) is less than the height H2 of the second copper layer segment (212); The tin layer (22) includes a first tin layer segment (221) located in the main body (2a) and a second tin layer segment (222) located in the connecting part (2b), wherein the height H3 of the first tin layer segment (221) is less than the height H4 of the second tin layer segment (222).

6. The back contact battery according to claim 5, characterized in that, The height H1 of the first copper layer segment (211) satisfies: 5μm≤H1≤12μm; The height H2 of the second copper layer segment (212) satisfies: 15μm≤H2≤22μm; The height H3 of the first tin layer segment (221) satisfies: 0.5μm≤H3≤2μm; The height H4 of the second tin layer segment (222) satisfies: 2μm≤H4≤3μm.

7. The back contact battery according to any one of claims 1-6, characterized in that, The back contact battery (10) also includes a fine grid (3) and an insulating member (4). The fine grid (3) is disposed on the back surface of the body (1). The fine grid (3) includes a first fine grid (31) and a second fine grid (32) that are alternately distributed in the length direction of the main grid (2). The first fine grid (31) is connected to the main grid (2), and the second fine grid (32) is spaced apart from the main grid (2); At least a portion of the insulating element (4) covers one end of the second fine gate (32) near the main gate (2) so that the second fine gate (32) is insulated from the main gate (2).

8. The back contact battery according to claim 7, characterized in that, The height H5 of the insulating component (4) and the height H6 of the connecting part (2b) satisfy the following condition: -5μm≤H6-H5≤15μm.

9. A back-contact stacked battery, characterized in that, It includes a back contact bottom cell (201) and a perovskite top cell (202), wherein the perovskite top cell (202) is electrically connected to the light-facing surface of the back contact bottom cell (201); The back contact bottom battery (201) includes: Ontology(1); The main gate (2) includes a copper layer (21) and a tin layer (22). The copper layer (21) is disposed on the back surface of the body (1), and the tin layer (22) covers the outer surface of the copper layer (21). Along the length of the main grid (2), the main grid (2) has alternating main body portions (2a) and connecting portions (2b), the height of the connecting portions (2b) being greater than the height of the main body portions (2a).

10. A photovoltaic module, characterized in that, include: A battery string includes a solder strip (30) and a plurality of photovoltaic cells, two adjacent photovoltaic cells are connected by the solder strip (30), the photovoltaic cells are back contact cells as described in any one of claims 1-8, or the photovoltaic cells are back contact stacked cells as described in claim 9, and the solder strip (30) is welded and fixed to the connecting part (2b); Encapsulation layer (40) is used to cover the surface of the battery string; A cover plate (50) is used to cover the surface of the encapsulation layer (40) away from the battery string.

11. The photovoltaic module according to claim 10, characterized in that, The yield strength of the welding strip (30) is 45MPa~65MPa.

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