Back contact photovoltaic module

Abstract

The utility model relates to the field of back contact photovoltaic, especially a back contact photovoltaic module, including the outer frame, still including T type solder strip, the inside of outer frame is provided with nine cell piece bodies, the bottom of cell piece body is provided with a plurality of cell piece grid lines, the bottom of cell piece body is provided with insulating ink, the bottom of cell piece grid line is provided with T type solder strip, the left and right sides of outer frame are fixedly connected with connecting block respectively, the inside of connecting block is movably connected with mounting block, the utility model discloses when the cell piece body is made, the conventional flat solder strip is replaced for T type solder strip, can directly with cell piece grid line good contact welding, need not rely on the tin paste printing to make up the height difference of insulating ink protection layer, thereby avoid the phenomenon of tin explosion in the high temperature alloying process of tin paste and the short circuit risk caused by the tin dregs spatter to the heterogeneous grid line, shorten the current transmission distance, improve the welding reliability and solar module efficiency simultaneously.

Description

Technical Field

[0001] This utility model relates to the field of back-contact photovoltaics, and in particular to a back-contact photovoltaic module. Background Technology

[0002] BC cells are a high-efficiency photovoltaic technology. Their core feature is that all metal electrode grid lines are moved to the back of the cell, leaving the front without any metal obstruction. This significantly improves the absorption and utilization efficiency of light, thereby increasing short-circuit current and conversion efficiency. In this structure, flat solder ribbons are key components responsible for connecting the cells in series and transmitting current to the external circuit. Solder paste is used for low-temperature adhesion and high-temperature soldering to ensure a reliable connection between the electrodes and the solder ribbons. Insulating ink forms an insulating layer on the cell surface to prevent short circuits and leakage between adjacent electrodes in the back contact structure. These three components work together to reduce optical loss, improve reliability, and ultimately achieve higher module output efficiency.

[0003] In traditional back-contact photovoltaic modules, the insulating ink creates a certain height after forming a protective layer, preventing direct soldering between the solder ribbon and the solar cell. Solder paste needs to be printed at the appropriate locations to fill the space. When the solder paste is alloyed with the solder ribbon at high temperatures, solder splattering is prone to occur during soldering. Solder dross falling onto the two opposite grid lines poses a short-circuit risk.

[0004] Therefore, in the traditional back-contact photovoltaic modules, the insulating ink has a certain height after forming protection, which makes it impossible to directly solder the solder ribbon and the cell. Solder paste needs to be printed in the corresponding position to make up the space. When the solder paste is alloyed with the solder ribbon at high temperature, solder splattering is likely to occur during soldering. Solder dross splashes onto the two opposite grid lines, which poses a short circuit risk. A back-contact photovoltaic module can be designed. Utility Model Content

[0005] To overcome the problem that the insulating ink has a certain height after forming a protective layer, which prevents the solder ribbon and the battery cell from being directly soldered, it is necessary to print solder paste in the corresponding position to fill the space. When the solder paste is alloyed with the solder ribbon at high temperature, solder splattering is prone to occur during soldering. The solder dross falling on the two opposite grid lines poses a short circuit risk.

[0006] The technical solution of this utility model is as follows: a back-contact photovoltaic module, including an outer frame; and also including a T-shaped welding strip. Nine solar cell bodies are arranged inside the outer frame. Multiple solar cell grid lines are arranged at the bottom of the solar cell bodies. Insulating ink is arranged at the bottom of the solar cell bodies. T-shaped welding strips are arranged at the bottom of the solar cell grid lines. Connecting blocks are fixedly connected to the left and right sides of the outer frame respectively. Mounting blocks are movably connected inside the connecting blocks. Rotating rods are threadedly connected inside the connecting blocks. A fixing plate is fixedly connected to the front end of the rotating rods.

[0007] Preferably, by replacing the conventional flat solder ribbon with a T-shaped solder ribbon during the manufacturing of the solar cell body, it can directly and well contact the solar cell grid lines for welding, without relying on solder paste printing to compensate for the height difference of the insulating ink protective layer. This avoids the risk of short circuits caused by solder splattering during the high-temperature alloying process of the solder paste and solder dross falling onto the irregular grid lines. At the same time, it shortens the current transmission distance, improves welding reliability and solar module efficiency.

[0008] Preferably, the connecting block has an internal threaded connection to a rotating rod, and the front end of the rotating rod is fixedly connected to a fixing plate.

[0009] Preferably, a silicone pad is fixedly connected to the front end of the fixing plate, and a throttle is fixedly connected to the rear end of the rotating rod.

[0010] Preferably, a fixing block is rotatably connected to the outer surface of the mounting block, and a connecting plate is fixedly connected to the bottom of the fixing block.

[0011] Preferably, a cylinder is fixedly connected to the bottom of the connecting plate, and a rotating block is rotatably connected to the bottom of the cylinder.

[0012] Preferably, the cylinder has a threaded rod inside, which is rotatably connected to the rotating block.

[0013] Preferably, the outer surface of the threaded rod has a socket, and the outer surface of the cylinder has the same socket.

[0014] Preferably, the socket is internally connected to a plug rod, and the bottom of the threaded rod is fixedly connected to a mounting plate.

[0015] The beneficial effects of this utility model are:

[0016] By replacing the conventional flat solder ribbon with a T-shaped solder ribbon during the manufacturing of the solar cell body, it can be directly and well contacted with the cell grid lines for welding. There is no need to rely on solder paste printing to compensate for the height difference of the insulating ink protective layer. This avoids the risk of short circuits caused by solder splattering during the high-temperature alloying process of the solder paste and solder dross falling onto the irregular grid lines. At the same time, it shortens the current transmission distance, improves welding reliability and solar module efficiency. Attached Figure Description

[0017] Figure 1 The diagram shown is a three-dimensional structural schematic of this utility model;

[0018] Figure 2 The diagram shown is a three-dimensional lower cross-sectional view of the present invention.

[0019] Figure 3 The diagram shown is a three-dimensional front cross-sectional view of the present invention.

[0020] Figure 4 The diagram shown is a three-dimensional side sectional view of the present invention.

[0021] Figure 5 The diagram shown is a schematic diagram of the cylindrical three-dimensional side cross-section structure of this utility model.

[0022] Explanation of reference numerals in the attached drawings: 1. Solar cell body; 2. Solar cell grid line; 4. Insulating ink; 5. T-shaped welding strip; 6. Outer frame; 7. Connecting block; 8. Mounting block; 9. Silicone pad; 10. Fixing plate; 11. Rotating rod; 12. Rotating handle; 13. Fixing block; 14. Connecting plate; 15. Cylindrical rod; 16. Rotating block; 17. Threaded rod; 18. Insertion rod; 19. Insertion hole; 20. Mounting plate. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Back-contact (BC) cells significantly improve light absorption efficiency due to the absence of grid lines obstructing the front side, but the dense arrangement of electrodes on the back presents challenges for the soldering process. Traditional methods use flat solder ribbons and solder paste to connect the cells to the ribbons: first, insulating ink is printed on the grid lines to prevent short circuits; however, due to height differences in the insulating layers, additional solder paste is needed to fill the gaps, and then high-temperature soldering alloys the solder paste to form a conductive path. However, this approach has three major drawbacks: long current transmission path: the solder paste only connects the ribbon and grid lines at discrete points, requiring the current to detour through the ribbon, increasing series resistance and reducing module efficiency. To compensate for losses, thicker flat solder ribbons are needed, increasing costs. Complex process: the solder paste needs to be printed and pre-cured, increasing production steps and time. Risk of solder splatter and short circuits: during high-temperature soldering, solder paste is prone to splattering, and solder dross may bridge adjacent dissimilar grid lines, leading to short-circuit failure.

[0025] Using T-shaped solder ribbons instead of traditional flat solder ribbons and solder paste enables direct full-contact soldering between the ribbon and the cell grid lines. The T-shaped ribbon consists of a horizontal base and vertical protrusions. Its innovation lies in: The protrusions penetrate the insulating layer: the height of the protrusions is slightly greater than the thickness of the insulating ink, allowing them to be pressed into the ink gaps and directly contact the grid lines without the need for solder paste filling. Surface contact replaces point contact: traditional solder paste soldering only forms a partial connection, while the protrusions of the T-shaped ribbon are in full contact with the grid lines, significantly reducing contact resistance. Eliminates the solder paste process: It eliminates the solder paste printing and curing steps, simplifying the production process and completely eliminating the risk of solder splattering.

[0026] The raised portion of the T-shaped solder strip is made of highly conductive copper, and the top can be designed with serrations or waves to enhance the engagement with the grid lines. The width of the horizontal base matches the main grid of the solar cell to ensure efficient current collection. Insulating ink printing: Insulating ink is printed on the non-soldering area on the back of the solar cell, exposing only the grid line contact area. T-shaped solder strip positioning: The solder strip protrusion is precisely aligned with the grid lines, and mechanical pressure or thermal pressure is used to penetrate the ink layer. Laser welding: Local heating is used to alloy the solder strip with the grid lines, avoiding overall high-temperature damage to the solar cell. Current transmission optimization: Current flows directly from the grid lines into the T-shaped protrusion and then exits through the horizontal base, resulting in the shortest path and reduced resistance loss compared to the traditional detour path.

[0027] Compared to traditional solutions, the core advantages of T-shaped solder strips are reflected in three aspects: Improved electrical performance: Full grid contact reduces series resistance and increases module conversion efficiency. Enhanced reliability: Increased soldering area significantly improves resistance to mechanical vibration and thermal cycling, extending module lifespan. Elimination of solder paste material and printing equipment reduces production costs; and it eliminates short circuits caused by solder splattering.

[0028] This invention addresses key challenges in back-contact (BC) cell welding through an innovative T-shaped welding strip structure, offering high efficiency, reliability, and low cost. It is particularly suitable for high-density back-contact modules such as IBC and HJT cells. Future development could further optimize the protrusion shape, such as by using a nano-coating to enhance conductivity, or by integrating with an intelligent positioning system to achieve fully automated production. This technology provides a disruptive welding solution for the photovoltaic industry, driving BC technology towards higher efficiency and lower costs.

[0029] The performance of T-shaped solder ribbons is highly dependent on material selection and manufacturing process optimization. Regarding materials, the solder ribbon substrate typically uses high-purity oxygen-free copper to ensure conductivity, while the raised portions can be plated with silver or tin to enhance solderability and oxidation resistance. The insulating ink must be selected from types with high temperature resistance and low dielectric constant, such as polyimide or epoxy resin-based inks, to ensure that carbonization or peeling does not occur during soldering.

[0030] In terms of manufacturing process, the stamping and forming of T-shaped solder strips requires strict control over the height tolerance of the protrusions to avoid excessive damage to the solar cells or poor contact. Pulsed laser technology is used during welding, with energy density controlled to achieve rapid alloying while preventing the heat-affected zone from diffusing into the cell's PN junction. Furthermore, the alignment accuracy between the solder strip and the solar cell can be calibrated in real time using a machine vision system to ensure that each protrusion precisely corresponds to the center of the grid line.

[0031] Potential Technology Expansion and Compatibility: T-strip technology can be adapted to various novel battery structures: IBC cells: By optimizing the protrusion arrangement density and matching the finger grid lines of IBC cells, the carrier transport path is further shortened. Tandem perovskite cells: The low-temperature welding characteristics of the T-strip can avoid thermal damage to the perovskite layer. Flexible modules: Using ultra-thin copper foil to fabricate the T-strip, it is suitable for flexible photovoltaic applications.

[0032] Although the cost per meter of T-shaped solder ribbon is higher than that of flat solder ribbon, the overall cost is significantly lower: Material savings: Reduced use of solder paste and insulating ink due to elimination. Equipment investment: Elimination of solder paste printing machines and curing ovens, and shorter payback period for additional solder ribbon stamping equipment. Energy reduction: Reduced energy consumption in the soldering process. T-shaped solder ribbon technology is expected to become the standard solution for mass production of BC cells, and is anticipated to drive a breakthrough in photovoltaic module efficiency. Future research directions include: Intelligent soldering: Combining AI visual positioning and robotic pressing to achieve high soldering yield. Multi-busbar integration: Integrating multiple fine busbars on the horizontal substrate of the T-shaped solder ribbon, compatible with SMBB technology. Recycling-friendly design: Adopting an easy-peel structure to facilitate the recycling and reuse of copper after module retirement. The promotion of this technology will accelerate the development of the photovoltaic industry towards high efficiency and low levelized cost of electricity, contributing to the achievement of global carbon neutrality goals.

[0033] Please see Figures 1-5 This utility model provides an embodiment: a back-contact photovoltaic module includes an outer frame 6; it also includes a T-shaped solder ribbon 5. Nine solar cell bodies 1 are arranged inside the outer frame 6. Multiple solar cell grid lines 2 are arranged at the bottom of the solar cell bodies 1. Insulating ink 4 is arranged at the bottom of the solar cell bodies 1. T-shaped solder ribbons 5 are arranged at the bottom of the solar cell grid lines 2. Connecting blocks 7 are fixedly connected to the left and right sides of the outer frame 6 respectively. Mounting blocks 8 are movably connected inside the connecting blocks 7. A rotating rod 11 is threadedly connected inside the connecting blocks 7. A fixing plate 10 is fixedly connected to the front end of the rotating rod 11. By replacing the conventional flat solder ribbon with T-shaped solder ribbon 5 during the manufacturing of the solar cell bodies 1, it can directly contact the solar cell grid lines 2 for welding without relying on solder paste printing to compensate for the height difference of the insulating ink 4 protective layer. This avoids the risk of short circuit caused by solder splattering and solder dross falling onto the irregular grid lines during the high-temperature alloying process of the solder paste. At the same time, it shortens the current transmission distance, improves welding reliability and solar module efficiency.

[0034] Please see Figures 1-5In this embodiment, a rotating rod 11 is threadedly connected to the inside of the connecting block 7. A fixing plate 10 is fixedly connected to the front end of the rotating rod 11, and a silicone pad 9 is fixedly connected to the front end of the fixing plate 10. A handle 12 is fixedly connected to the rear end of the rotating rod 11. The mounting block 8 is inserted into the connecting block 7, and then the handle 12 is rotated to drive the rotating rod 11 to rotate. The rotating rod 11 moves back and forth on the connecting block 7 through the thread. A fixing block 13 is rotatably connected to the outer surface of the mounting block 8, and a connecting plate 14 is fixedly connected to the bottom of the fixing block 13. The rotating rod 11 pushes the fixing plate 10 and the silicone pad 9 to move and fix the mounting block 8 in the connecting block 7. The silicone pad 9 can increase the friction of the contact surface and improve the stability of the installation. A cylinder 15 is fixedly connected to the bottom of the connecting plate 14, and a rotating block 16 is rotatably connected to the bottom of the cylinder 15. When adjusting the angle of the battery cell, the mounting block 8 rotates between the two fixing blocks 13.

[0035] Please see Figures 2-5 In this embodiment, a threaded rod 17 is movably connected inside the cylinder 15. The threaded rod 17 is rotatably connected to the rotating block 16. When adjusting the height, the rotating block 16 is rotated, causing the rotating block 16 to rotate and move up and down on the threaded rod 17. When the rotating block 16 moves, it pushes the cylinder 15 to move upward, thereby realizing the height adjustment. The outer surface of the threaded rod 17 is provided with a socket 19, and the outer surface of the cylinder 15 is provided with the same socket 19. A plug rod 18 is movably connected inside the socket 19. A mounting plate 20 is fixedly connected to the bottom of the threaded rod 17. When fixing the height position, the socket 19 on the cylinder 15 and the threaded rod 17 are aligned one by one. Then, the plug rod 18 is inserted into the socket 19 and fixed.

[0036] During the fabrication of the solar cell body 1, the conventional flat solder ribbon is replaced with a T-shaped solder ribbon 5. The T-shaped solder ribbon 5 can make good contact with the solar cell grid lines 2 for soldering, eliminating the need for solder paste printing, shortening the current transmission distance, improving soldering reliability, and reducing the risk of short circuits. This shortened current transmission distance also improves the efficiency of the solar module. When adjusting the angle of the solar cell, the mounting block 8 rotates between the two fixed blocks 13. When adjusting the height, the rotating block 16 is rotated, causing it to rotate and move up and down on the threaded rod 17. As the rotating block 16 moves, it pushes the cylinder 15 upwards. The height can be adjusted by moving the cylinder 15 to the corresponding insertion hole 19 on the threaded rod 17. Then, the insertion rod 18 is inserted into the insertion hole 19 and fixed. The mounting block 8 is inserted into the connecting block 7. Then, the handle 12 is turned to drive the rotating rod 11 to rotate. The rotating rod 11 moves back and forth on the connecting block 7 through the thread. The rotating rod 11 pushes the fixing plate 10 and the silicone pad 9 to move and fix the mounting block 8 in the connecting block 7. The silicone pad 9 can increase the friction of the contact surface and improve the stability of the installation.

Claims

1. A back-contact photovoltaic module, comprising an outer frame (6); characterized in that: It also includes a T-shaped welding strip (5), nine battery cell bodies (1) are arranged inside the outer frame (6), multiple battery cell grid lines (2) are arranged at the bottom of the battery cell body (1), insulating ink (4) is arranged at the bottom of the battery cell body (1), T-shaped welding strip (5) is arranged at the bottom of the battery cell grid line (2), connecting blocks (7) are fixedly connected to the left and right sides of the outer frame (6), mounting blocks (8) are movably connected inside the connecting blocks (7), rotating rods (11) are threaded inside the connecting blocks (7), and a fixing plate (10) is fixedly connected to the front end of the rotating rods (11).

2. A back-contact photovoltaic module according to claim 1, characterized in that: The front end of the fixed plate (10) is fixedly connected to a silicone pad (9), and the rear end of the rotating rod (11) is fixedly connected to a throttle (12).

3. A back-contact photovoltaic module according to claim 1, characterized in that: The outer surface of the mounting block (8) is rotatably connected to a fixing block (13), and the bottom of the fixing block (13) is fixedly connected to a connecting plate (14).

4. A back-contact photovoltaic module according to claim 3, characterized in that: A cylinder (15) is fixedly connected to the bottom of the connecting plate (14), and a rotating block (16) is rotatably connected to the bottom of the cylinder (15).

5. A back-contact photovoltaic module according to claim 4, characterized in that: The cylinder (15) has a threaded rod (17) inside, which is rotatably connected to the rotating block (16).

6. A back-contact photovoltaic module according to claim 5, characterized in that: The outer surface of the threaded rod (17) is provided with a socket (19), and the outer surface of the cylinder (15) is provided with the same socket (19).

7. A back-contact photovoltaic module according to claim 6, characterized in that: The insertion hole (19) is internally connected to a rod (18), and the bottom of the threaded rod (17) is fixedly connected to a mounting plate (20).

Images