Series connection method of back contact batteries

Abstract

The invention provides a series connection method of back contact batteries, which relates to the technical field of batteries and comprises the following steps: S1, printing solder paste on a battery piece bonding pad; s2, solder paste reflow soldering; s3, slicing the battery piece; s4, transparent interconnecting strip traction; s5, performing laser wire stripping on the transparent interconnection strip; s6, a scaling powder is sprayed at the wire stripping position; s7, cutting the transparent interconnecting strips; and S8, the transparent interconnection strips are placed and welded to form a battery string. According to the invention, the isolation and interconnection of the positive and negative auxiliary grids are realized by adopting the insulating interconnection strip selectively stripped and exposed by laser, the interconnection strip is a complete insulator, the insulating property of the interconnection strip does not depend on the accuracy of a printing process, the defect of lack of glue easily occurring in an insulating glue printing process is avoided, and the strict accuracy requirement of insulating glue printing does not need to be met; the use reliability of the battery string is greatly improved; the transparent material is adopted to prepare the insulating part of the interconnection strip, a traditional non-transparent insulating glue structure is replaced, the effective light receiving area of the back face of the cell is greatly increased, and the photoelectric conversion efficiency is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a method for connecting back-contact batteries in series. Background Technology

[0002] Back-contact solar cells (BC cells) are a general term for crystalline silicon solar cells in which both the PN junction and the metal contact are located on the back of the cell. It is not a single cell type, but rather a platform-type structural optimization technology that can be superimposed with various photovoltaic technologies. Unlike traditional cells with grid lines on the front, BC cells only retain an anti-reflection passivation film on the front, without any metal grid lines obstructing the view. The back electrodes are mostly arranged in an interdigitated or parallel pattern. Utilizing the high carrier mobility of the n-type substrate, a built-in electric field is formed through the alternating P and N-type contact regions on the back. This allows the electron-hole pairs generated by photon excitation to be efficiently separated and discharged through the back electrodes, thereby reducing light energy loss and improving power generation efficiency.

[0003] In existing back-contact batteries, the two polarities of the sub-grids are staggered. The current isolation method is to achieve this by printing and curing insulating adhesive. This method not only has strict requirements for printing accuracy but also has high costs. At the same time, the insulating adhesive is prone to insufficient adhesive during the printing process, which may lead to the risk of short circuit between the positive and negative sub-grids of the battery cell. In addition, the back-side light utilization rate of existing back-contact battery modules is still at a low level, and the photoelectric conversion efficiency is low. How to further improve the bifacial power generation utilization rate of back-contact batteries has become a technical problem that the industry urgently needs to solve. Summary of the Invention

[0004] This invention provides a method for connecting back-contact batteries in series to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention discloses a method for connecting back-contact batteries in series, comprising the following steps: S1: printing solder paste on the battery pads; S2: reflow soldering of solder paste; S3: slicing the battery cells; S4: pulling transparent interconnect strips; S5: laser stripping of transparent interconnect strips; S6: spraying flux at the stripped area; S7: cutting transparent interconnect strips; S8: arranging and welding transparent interconnect strips to form a battery string.

[0006] Preferably, in step S1, the battery cell is a back-contact battery cell, the circuit of the battery cell is arranged alternately along the back main grid, and the battery cell type includes TBC, IBC, and HBC; the number of positive and negative grid lines is 18 to 22. The solder paste is a special solder paste for back contact batteries. Its components are tin, silver, and copper, with a flux content of 10-11.5% and a melting point of 200-217℃. Solder paste printing is performed automatically using a solder paste printer. The size of the solder paste to be printed is consistent with the size of the battery cell pads, and the printing height is set within the range of 0.08 to 0.10 mm.

[0007] Preferably, in step S2, the battery cell with printed solder paste is passed through a solder paste reflow device, heated to melt and reflow the solder paste, and then cooled to form a permanent solder joint; In step S3, the battery cell is cut into several segments.

[0008] Preferably, in step S4, the transparent interconnecting strip includes a copper substrate inner layer and an insulating and heat-resistant transparent outer layer. The thickness of the insulating and heat-resistant transparent outer layer ranges from 0.02 to 0.06 mm; the temperature resistance ranges from 220 to 260°C; and the transmittance is 75% to 85%.

[0009] Preferably, in step S5, an automatic wire stripping process is used; in step S6, a spraying device is used to spray flux onto the stripped area to remove impurities and oxides from the inner surface of the copper substrate.

[0010] Preferably, in steps S7-S8, the transparent interconnect strip is cut to the length required for interconnection with the battery cell; Place the cut transparent interconnect strips at the designated electrode positions on the back of the wafer; align the stripped sections of the transparent interconnect strips with the solder paste positions on the cell pads; The transparent interconnecting strip is fixed and transported to the welding station by an automatic transfer device for automatic welding. After welding, a series connection of back-contact batteries is formed.

[0011] Preferably, the spraying device includes a spraying box with a through channel inside. A recovery tank and a drying tank are installed on the lower side wall of the spraying box. A guide rail is installed on the lower side wall of the channel. A symmetrical sliding rail is installed on the guide rail. A moving block is installed on the sliding rail. A mounting plate is fixedly installed on the moving block. A drive motor is installed on the mounting plate. A sleeve cover is installed on the lower side of the mounting plate. A spraying assembly is installed inside the sleeve cover. The recycling tank is equipped with a filter screen, and a recycling pipe is connected through the rear of the recycling tank; the drying tank is equipped with heating wires.

[0012] Preferably, the injection assembly includes an air-blowing box, which is disposed inside the sleeve cover and fixedly connected to the lower surface of the mounting plate. A rotating rod is fixedly connected to the lower output end of the drive motor. The rotating rod rotates through the air-blowing box and is provided with several blades, which are disposed inside the air-blowing box. Several evenly distributed air outlet pipes are provided through the air-blowing box. A sphere is fixedly disposed at the lower end of the rotating rod, and an arc plate is assembled and connected to the sphere. A cross connecting rod is fixedly disposed at the lower end of the arc plate, and a vertical rod is fixedly disposed at the other end of the cross connecting rod. The lower end of the vertical rod is connected to the same rotating ring.

[0013] Preferably, a rotating box is fixedly installed at the lower end of the air blowing box. A rotating rod rotates through the rotating box, and a semi-bevel gear is fixedly installed on the rotating rod. Rotating rods are symmetrically connected to the front and rear sides of the rotating box. A bevel gear is fixedly installed on the rotating rod. Two bevel gears are symmetrically arranged front and rear and mesh with the semi-bevel gear. A gear is fixedly installed on the side of the two rotating rods that are close to each other. An arc-shaped through groove is opened on the rotating box. An arc-shaped rack is slidably installed on the arc-shaped through groove. A through groove is provided in the center of the arc-shaped rack, and the rotating rod passes through the through groove.

[0014] Preferably, an arc-shaped connecting rod is fixedly installed at the lower right end of the arc-shaped rack, and an arc-shaped box is fixedly installed at the other end of the arc-shaped connecting rod. A circular groove is provided inside the arc-shaped box, and a rotating ring is slidably connected to the circular groove. Several through holes are also provided on the rotating ring. Several arc-shaped protrusions are fixedly installed on the sphere, and several arc-shaped grooves are provided inside the arc plate. Several arc-shaped protrusions and several arc-shaped grooves are matched. A storage box is fixedly installed at the upper end of the spray box, and a recycling pipe is connected to the storage box. A corrugated connecting pipe is connected to the lower side of the storage box. The corrugated connecting pipe passes through the sleeve cover on the left side. A joint is provided on the arc-shaped box, and the corrugated connecting pipe is connected to the joint.

[0015] Compared with the prior art, the present invention provides a series connection method for back contact batteries, which has the following beneficial effects: The present invention abandons the traditional insulating glue isolation scheme and uses laser selectively exposed insulating interconnect strips to achieve the isolation and interconnection of positive and negative electrode sub-grids - the interconnect strip itself is a complete insulator, and its insulation performance does not depend on the precision of the printing process, completely avoiding the glue shortage defect that is easy to occur in the insulating glue printing process, fundamentally eliminating the risk of short circuit of positive and negative electrode sub-grids caused by process defects, while not having to meet the strict precision requirements of insulating glue printing, significantly reducing the difficulty of process control, and greatly improving the product yield and long-term reliability of battery strings; The innovative use of transparent materials to prepare the insulating part of the interconnect strip replaces the traditional opaque insulating adhesive structure, allowing scattered and reflected light incident from the back to penetrate the interconnect strip and reach the surface of the solar cell. This effectively solves the core problem of blocking light from the back of the cell in traditional solutions, significantly increases the effective light-receiving area on the back of the cell, and greatly improves the photoelectric conversion efficiency. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the process of the present invention; Figure 2 This is a schematic diagram of the structure of the battery cell of the present invention; Figure 3 This is a schematic diagram of the structure of the solder paste after printing according to the present invention; Figure 4 This is a schematic diagram of the segmented structure of the present invention; Figure 5 This is a schematic diagram of the structure of the back-contact transparent interconnect strip of the present invention; Figure 6 This is a schematic diagram of the transparent interconnect stripping structure of the present invention; Figure 7 This is a schematic diagram of the coating structure at the stripped area of ​​the present invention; Figure 8 This is a schematic diagram of the transparent interconnect strip stripping and cutting structure of the present invention; Figure 9 This is a schematic diagram of the arrangement and welding of the transparent interconnect strips according to the present invention; Figure 10 This is a schematic diagram of the battery string structure of the present invention; Figure 11 This is a schematic diagram of the internal structure of the spray box of the present invention; Figure 12 This is a schematic diagram of the internal structure of the recycling tank of the present invention; Figure 13 This is a side view of the slide rail of the present invention; Figure 14 This is a schematic diagram of the internal structure of the sleeve cap of the present invention; Figure 15 This is a side view of the internal structure of the rotating box of the present invention; Figure 16 This is a schematic diagram of the through-slot of the present invention; Figure 17 This is a schematic diagram of the internal structure of the air blowing box of the present invention; Figure 18 This is a schematic diagram illustrating the fit between the arc plate and the sphere of the present invention; Figure 19 This is a top view of the arc box and rotating ring of the present invention.

[0017] In the diagram: 1. Battery cell; 2. Solder paste; 3. Segmentation; 4. Inner layer of copper substrate; 5. Insulating, heat-resistant, transparent outer layer; 6. Stripping point; 7. Spraying box; 8. Storage box; 9. Slide rail; 10. Channel; 11. Drying tank; 12. Guide rail; 13. Recycling tank; 14. Sleeve cover; 15. Corrugated connecting pipe; 16. Moving block; 17. Mounting plate; 18. Drive motor; 19. Filter screen; 20. Recycling pipe; 2 1. Air blowing box; 22. Arc-shaped rack; 23. Arc-shaped connecting rod; 24. Circular arc box; 25. Connector; 26. Sphere; 27. Air outlet pipe; 28. Rotating rod; 29. ​​Rotating box; 30. Half bevel gear; 31. Gear; 32. Rotating rod; 33. Bevel gear; 34. Through groove; 35. Blade; 36. Arc-shaped protrusion; 37. Circular arc plate; 38. Cross connecting rod; 39. Vertical rod; 40. Rotating ring. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Example 1: An embodiment of the present invention provides a method for connecting back-contact batteries in series, such as... Figures 1-10 As shown, the process includes the following steps: S1: Printing solder paste 2 on the pads of the battery cell 1; S2: Reflow soldering of solder paste 2; S3: Slicing the battery cell 1; S4: Pulling the transparent interconnect strip; S5: Laser stripping of the transparent interconnect strip; S6: Spraying flux on the stripped area 6; S7: Cutting the transparent interconnect strip; S8: Placing and soldering the transparent interconnect strip to form a battery string.

[0022] The working principle and beneficial effects of the above technical solution are as follows: In step S1, special solder paste 2 is printed on the pads of the back contact cell 1 to provide a reliable conductive foundation for subsequent interconnection welding; in step S2, the solder paste 2 is melted and cooled by reflow soldering to form permanent solder joints, strengthening the connection strength between the pads and the interconnection structure; in step S3, the cell 1 is cut into several segments 3 to adapt to the layout requirements of large-scale series connection; in steps S4-S6, the transparent interconnect strip is processed. First, the interconnect strip is pulled and the inner layer 4 of the copper substrate to be welded is precisely exposed by laser wire stripping process (forming the stripping area 6). Then, flux is sprayed on the stripping area 6 to remove surface impurities and oxides and ensure the conductivity of the weld; in steps S7-S8, the cut transparent interconnect strip is placed in the preset position so that the stripping area 6 is precisely aligned with the solder paste 2 of the pads of the segment 3. After automatic welding, the inner layer 4 of the copper substrate of the transparent interconnect strip forms a conductive connection with the pads, and the insulating and heat-resistant transparent outer layer 5 achieves physical isolation between adjacent positive and negative electrode sub-gates, finally forming a stable and reliable battery string.

[0023] Abandoning the traditional insulating adhesive printing isolation scheme, this invention adopts a transparent interconnecting strip with a built-in insulating, heat-resistant, and transparent outer layer. Its insulation performance is determined by its own structure, eliminating the need for printing process precision and fundamentally preventing short circuits between the positive and negative electrodes caused by insufficient insulating adhesive or printing deviations. It also eliminates the need to meet the stringent precision requirements of insulating adhesive printing, significantly reducing process control difficulty and greatly improving the product yield and long-term reliability of the battery string. Furthermore, the innovative use of transparent materials to prepare the insulating portion of the interconnecting strip replaces the traditional opaque insulating adhesive structure, allowing scattered and reflected light incident from the back to penetrate the interconnecting strip and reach the surface of the battery cell. This effectively solves the core problem of traditional solutions blocking back-side light, significantly increasing the effective light-receiving area on the back of the battery and greatly improving photoelectric conversion efficiency.

[0024] Example 2: Based on Example 1 above, as follows Figures 1-4 As shown, in step S1, the battery cell 1 is a back-contact battery cell, and the circuit of the battery cell 1 is arranged alternately along the back main grid. The battery cell 1 type includes TBC, IBC, and HBC; the number of positive and negative grid lines is 18 to 22. Among them, the size of the battery cell 1 is a conventional mainstream size (182×182mm, 182×183.75mm, 182×210mm or other conventional sizes). Solder paste 2 is a special solder paste for back contact batteries. Its composition is tin, silver and copper. The ratio of tin 96.5, silver 3.0 and copper 0.5 is preferred. The flux content is 10 to 11.5%. The melting point of solder paste 2 is 200 to 217°C. Solder paste 2 is printed automatically using a solder paste printer. The size of the solder paste 2 is consistent with the size of the pads of the battery cell 1, and the printing height is set in the range of 0.08 to 0.10 mm.

[0025] Preferably, in step S2, the battery cell 1 with printed solder paste 2 is passed through a solder paste reflow device, heated to melt and reflow the solder paste 2, and then cooled to form a permanent solder joint; In step S3, the battery cell 1 is cut into several segments 3.

[0026] The beneficial effects of the above technical solution are as follows: it clarifies that the battery cell 1 covers mainstream back contact types such as TBC, IBC, and HBC, and is compatible with conventional mainstream sizes such as the 182 series, breaking the limitation of a single type / size. It can be widely compatible with existing back contact battery production lines and module packaging requirements, significantly expanding the scope of application of the technology; the limitation of 18 to 22 positive and negative grid lines not only ensures current transmission efficiency, but also precisely matches the stripping spacing and welding points of the transparent interconnect strip, reducing the difficulty of process adaptation. Solder paste 2 uses a special tin-silver-copper ratio: 96.5% tin, 3.0% silver, and 0.5% copper (by weight). This composition ratio significantly improves the mechanical strength, conductivity, and corrosion resistance of the solder joints. Combined with a melting point of 200–217°C, it can adapt to the temperature requirements of subsequent soldering processes, avoiding high-temperature failure or low-temperature cold solder joints. The flux content of 10–11.5% and precise printing parameters (size matching, height 0.08–0.10 mm) ensure full contact between the solder paste and the inner layer 4 of the transparent interconnect strip copper substrate, reducing contact resistance and improving the overall conductivity and long-term stability of the battery string.

[0027] Example 3: Based on Example 2 above, as follows Figure 1 , Figures 5-10 As shown, the transparent interconnecting strip includes a copper substrate inner layer 4 and an insulating and heat-resistant transparent outer layer 5. The thickness of the insulating and heat-resistant transparent outer layer 5 ranges from 0.02 to 0.06 mm; the temperature range is 220 to 260 °C; and the transmittance is 75% to 85%.

[0028] The transparent interconnecting strips of the roll are straightened using a traction module (automatic welding equipment).

[0029] Among them, the inner layer 4 of the copper substrate can be made of flat welding strip or round wire welding strip. The diameter of the welding strip is determined according to the size of the grid line of the battery cell, and plays the role of current transmission. The insulating, heat-resistant, and transparent outer layer 5 is made of modified transparent polyester or transparent polyamide-imide material coated with insulating material, or other insulating, heat-resistant, and transparent materials, which serve to provide insulation and light transmission. Preferably, in step S5, an automatic wire stripping process is used; in step S6, a spraying device is used to spray flux onto the stripped area 6 to remove impurities and oxides from the surface of the inner layer 4 of the copper substrate.

[0030] In step S5, the outer stripping length of the transparent interconnect strip (≥ solder paste printing length of about 1mm, too long will cause short circuit risk) and the distance (distance between two solder joints) are set according to the size spacing of the solder paste printing of the battery cell. This can be set by a computer program. Preferably, in steps S7-S8, the transparent interconnect strip is cut to the length required for interconnection with the battery cell; Place the cut transparent interconnect strip at the designated electrode position on the back of the wafer 3; align the stripped part 6 of the transparent interconnect strip with the solder paste position of the battery cell pad 2; The transparent interconnecting strip is fixed and transported to the welding station by an automatic transfer device for automatic welding. After welding, a series connection of back-contact batteries is formed.

[0031] The beneficial effects of the above technical solution are as follows: the insulating and heat-resistant transparent outer layer 5 of the transparent interconnect strip is an integrated structure, and its insulation performance is not affected by the printing process. Combined with the laser wire stripping process (the computer program sets the wire stripping size ≥ 1mm of solder paste length), the stripping range can be precisely controlled. The insulating and heat-resistant transparent outer layer 5 has a transmittance of 75% to 85% and a thickness of only 0.02 to 0.06mm, which hardly blocks the back light. Combined with its dual characteristics of heat resistance and insulation, it can achieve the isolation function while allowing the back scattered light and reflected light to fully penetrate to the surface of the cell, further improving the power generation efficiency of the module and giving full play to the structural advantages of the back contact cell.

[0032] The flux is sprayed onto the stripped area 6 to effectively remove impurities and oxides from the surface of the inner layer 4 of the copper substrate, thereby improving the wettability of the solder. The inner layer 4 of the copper substrate can be selected with flat solder strips or round wire solder strips to adapt to different grid line sizes of solar cells, ensuring that the current transmission path is matched and reducing contact resistance.

[0033] Example 4: Based on Examples 1-3, such as Figures 11-19 As shown, the spraying device includes a spraying box 7, a through channel 10 is provided inside the spraying box 7, a recovery tank 13 and a drying tank 11 are provided on the lower side wall of the spraying box 7, a guide rail 12 is provided on the lower side wall of the channel 10, a left-right symmetrical slide rail 9 is provided on the guide rail 12, a moving block 16 is provided on the slide rail 9, a mounting plate 17 is fixedly provided on the moving block 16, a drive motor 18 is installed on the mounting plate 17, a sleeve cover 14 is provided on the lower side of the mounting plate 17, and a spraying assembly is provided inside the sleeve cover 14; A filter screen 19 is installed inside the recycling tank 13, and a recycling pipe 20 is connected through the rear side of the recycling tank 13; an electric heating wire is installed inside the drying tank 11.

[0034] The sleeve cover 14 has symmetrical through grooves on the left and right sides, which are used for the passage of transparent interconnecting strips.

[0035] The working principle and beneficial effects of the above technical solution are as follows: The transparent interconnect strip passes through the channel 10 from left to right. The guide rail 12 cooperates with the slide rail 9 to provide a stable moving trajectory for the moving block 16, thereby driving the spraying component in the mounting plate 17 and the lower sleeve cover 14 to move synchronously (generally, the slide rail 9 does not move on the guide rail 12). The sleeve cover 14 will match the recycling tank 13 and the drying tank 11. The spraying component on the left sprays flux onto the stripped wire 6 in the recycling tank 13. During the spraying process, excess flux drips into the recycling tank 13 on the lower side wall of the spraying box 7. After the impurities are filtered by the filter screen 19, the flux is recycled and reused through the recycling pipe 20. After the spraying cleaning is completed, the transparent interconnect strip moves to the right, and the cleaned stripped wire 6 enters the drying tank 11. The spraying component on the right sprays air, and the heating wire in the drying tank 11 can quickly dry the sprayed transparent interconnect strip, remove excess moisture from the flux, and avoid residual moisture affecting the subsequent welding quality.

[0036] The filter screen 19 inside the recycling tank 13 can effectively filter excess flux dripping during the spraying process. After removing impurities, it is recycled to the storage device (such as the storage box 8 mentioned later) through the recycling pipe 20, realizing the recycling of flux and avoiding resource waste. The heating wire inside the drying tank 11 can quickly dry the transparent interconnect strip after the flux is sprayed, removing moisture and volatile components from the flux, and avoiding defects such as bubbles and oxidation caused by residual moisture during the welding process, making it more practical.

[0037] Example 5: Based on Example 4 above, as follows Figures 11-19 As shown, the injection assembly includes an air-blowing box 21, which is located inside the sleeve cover 14. The air-blowing box 21 is fixedly connected to the lower surface of the mounting plate 17. The lower output end of the drive motor 18 is fixedly connected to a rotating rod 28. The rotating rod 28 rotates through the air-blowing box 21. Several blades 35 are provided on the rotating rod 28 and are located inside the air-blowing box 21. Several evenly distributed air outlet pipes 27 are provided through the air-blowing box 21. A sphere 26 is fixedly provided at the lower end of the rotating rod 28. An arc plate 37 is assembled and connected to the sphere 26. A cross connecting rod 38 is fixedly provided at the lower end of the arc plate 37. A vertical rod 39 is fixedly provided at the other end of the cross connecting rod 38. The lower end of the vertical rod 39 is connected to the same rotating ring 40.

[0038] Preferably, a rotating box 29 is fixedly installed at the lower end of the air blowing box 21. A rotating rod 28 rotates through the rotating box 29. A half-bevel gear 30 is fixedly installed on the rotating rod 28. Rotating rods 32 are symmetrically rotatably connected to the front and rear sides of the rotating box 29. A bevel gear 33 is fixedly installed on the rotating rod 32. The two bevel gears 33 are symmetrically arranged front and rear. The bevel gears 33 mesh with the half-bevel gear 30. A gear 31 is fixedly installed on the side of the two rotating rods 32 that are close to each other. An arc-shaped through groove is opened on the rotating box 29. An arc-shaped rack 22 is slidably arranged on the arc-shaped through groove. A through groove 34 is provided in the center of the arc-shaped rack 22. The rotating rod 28 passes through the through groove 34.

[0039] Preferably, an arc-shaped connecting rod 23 is fixedly installed at the lower right end of the arc-shaped rack 22, and an arc-shaped box 24 is fixedly installed at the other end of the arc-shaped connecting rod 23. A circular groove is provided inside the arc-shaped box 24, and the rotating ring 40 is slidably connected to the circular groove. Several through holes are also provided on the rotating ring 40. Several arc-shaped protrusions 36 are fixedly installed on the sphere 26, and several arc-shaped grooves are provided inside the arc-shaped plate 37. Several arc-shaped protrusions 36 cooperate with several arc-shaped grooves. A storage box 8 is fixedly installed at the upper end of the spray box 7. The recycling pipe 20 is connected to the storage box 8. A corrugated connecting pipe 15 is connected to the lower side of the storage box 8. The corrugated connecting pipe 15 passes through the sleeve cover 14 on the left side. A joint 25 is provided on the arc-shaped box 24, and the corrugated connecting pipe 15 is connected to the joint 25.

[0040] The arc-shaped box 24 on the right side is also equipped with a connector 25, and a pipe (not shown in the figure) is connected through the air blowing box 21 on the right side. The pipe is connected to the connector 25 on the right side. The jet component on the right side sprays air, which will form multiple airflows in the drying tank 11 to accelerate the drying effect.

[0041] The working principle and beneficial effects of the above technical solution are as follows: the drive motor 18 starts and drives the rotating rod 28 to rotate. The rotating rod 28 drives several blades 35 in the air blowing box 21 to rotate at high speed, so that a stable airflow is generated in the air blowing box. The airflow is sprayed out in a direction through the air outlet pipes 27 evenly distributed on the box wall, providing airflow assistance for subsequent flux spraying. The semi-bevel gear 30 on the rotating rod 28 meshes with the two bevel gears 33 inside the rotating box 29, driving the rotating rod 32 and gear 31 to rotate synchronously. The gear 31 meshes with the arc-shaped rack 22, driving the arc-shaped rack 22 to slide back and forth along the arc-shaped through groove of the rotating box 29. At the same time, the ball 26 at the lower end of the rotating rod 28 is adapted to the arc-shaped groove of the arc plate 37 through the arc-shaped protrusion 36 (that is, the arc plate 37 can form a sliding fit with the arc-shaped protrusion 36, while not affecting the arc-shaped protrusion 36 driving the arc plate 37 to rotate), driving the rotating ring 40 connected by the arc plate 37, the cross connecting rod 38 and the vertical rod 39 to rotate synchronously. The sliding of the arc-shaped rack 22 drives the arc box 24 to swing through the arc connecting rod 23. Combined with the rotation of the rotating ring 40, the "swing + rotation" multi-angle movement of the spray end is realized. The flux in the storage box 8 enters the arc box 24 through the corrugated connecting pipe 15 and the connector 25 on the arc box 24. The circular groove on the inner side of the arc box 24 is sealed and slidably connected to the rotating ring 40 to ensure that the flux does not leak. Several through holes on the rotating ring 40 serve as nozzles, and under the drive of multi-dimensional motion, the flux is evenly sprayed onto the stripped area 6 of the transparent interconnect strip. At the same time, the airflow sprayed from the air blowing box 21 can disperse the flux droplets, making them more evenly cover the surface of the inner layer 4 of the copper substrate, and can accelerate the dripping of excess flux into the recycling tank 13. After being filtered by the filter screen 19, it flows back to the storage box 8 through the recycling pipe 20 to form a cycle for reuse.

[0042] The spraying assembly uses a multi-dimensional motion mode of "swinging + rotation" combined with airflow-assisted dispersion to ensure that the flux can cover the inner layer 4 of the copper substrate at the stripped wire 6 in all directions without dead angles. The precise targeted spraying design avoids flux contamination of the insulating, heat-resistant, and transparent outer layer 5, ensuring the removal of impurities and oxides while preventing insulation layer contamination from affecting the isolation performance. This significantly improves the wettability and conductivity stability of the solder joint, further reducing the risk of poor soldering and excessive contact resistance.

[0043] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

Claims

1. A method for connecting a back-contact battery in series, characterized in that, Includes the following steps: S1: Printing of solder paste (2) on the pads of the battery cell (1); S2: Reflow soldering of solder paste (2); S3: Slicing of the battery cell (1); S4: Pulling of transparent interconnect strips; S5: Laser stripping of transparent interconnect strips; S6: Spraying flux on the stripped area (6); S7: Cutting of transparent interconnect strips; S8: Placing and welding of transparent interconnect strips to form a battery string.

2. The method for connecting a back-contact battery in series according to claim 1, characterized in that, In step S1, the battery cell (1) is a back-contact battery cell, and the circuit of the battery cell (1) is arranged alternately along the back main grid. The battery cell (1) type includes TBC, IBC, and HBC; the number of positive and negative grid lines is 18 to 22. Solder paste (2) is a special solder paste for back contact batteries. Its components are tin, silver and copper, and the flux content is 10-11.5%. The melting point of solder paste (2) is 200-217℃. The solder paste (2) is printed automatically using a solder paste printer. The size of the solder paste (2) is consistent with the size of the pads of the battery cell (1), and the printing height is set in the range of 0.08 to 0.10 mm.

3. The method for connecting a back-contact battery in series according to claim 2, characterized in that, In step S2, the battery cell (1) with printed solder paste (2) is passed through the solder paste reflow equipment, heated to melt the solder paste (2) and reflow, and then cooled to form a permanent solder joint; In step S3, the battery cell (1) is cut into several segments (3).

4. The method for connecting a back-contact battery in series according to claim 3, characterized in that, In step S4, the transparent interconnecting strip includes a copper substrate inner layer (4) and an insulating and heat-resistant transparent outer layer (5). The thickness of the insulating and heat-resistant transparent outer layer (5) ranges from 0.02 to 0.06 mm; the temperature range is 220 to 260 °C; and the transmittance is 75% to 85%.

5. The method for connecting a back-contact battery in series according to claim 4, characterized in that, In step S5, laser wire stripping process is used for automatic wire stripping; in step S6, a spraying device is used to spray flux on the stripped area (6) to remove impurities and oxides from the surface of the inner layer (4) of the copper substrate.

6. The method for connecting a back-contact battery in series according to claim 5, characterized in that, In steps S7-S8, the transparent interconnect strip is cut to the length required for interconnection with the battery cells; Place the cut transparent interconnect strip at the designated electrode position on the back of the slice (3); align the stripped part (6) of the transparent interconnect strip with the position of the solder paste (2) on the battery cell pad; The transparent interconnecting strip is fixed and transported to the welding station by an automatic transfer device for automatic welding. After welding, a series connection of back-contact batteries is formed.

7. The method for connecting a back-contact battery in series according to claim 5, characterized in that, The spraying device includes a spraying box (7), a through channel (10) is provided inside the spraying box (7), a recovery tank (13) and a drying tank (11) are provided on the lower side wall of the spraying box (7), a guide rail (12) is provided on the lower side wall of the channel (10), a left-right symmetrical slide rail (9) is provided on the guide rail (12), a moving block (16) is provided on the slide rail (9), a mounting plate (17) is fixedly provided on the moving block (16), a drive motor (18) is installed on the mounting plate (17), a sleeve cover (14) is provided on the lower side of the mounting plate (17), and a spraying assembly is provided inside the sleeve cover (14); A filter screen (19) is installed inside the recycling tank (13), and a recycling pipe (20) is connected through the rear side of the recycling tank (13); an electric heating wire is installed inside the drying tank (11).

8. The method for connecting a back-contact battery in series according to claim 7, characterized in that, The injection assembly includes an air box (21), which is located inside the sleeve cover (14). The air box (21) is fixedly connected to the lower surface of the mounting plate (17). The lower output end of the drive motor (18) is fixedly connected to a rotating rod (28). The rotating rod (28) rotates through the air box (21). Several blades (35) are provided on the rotating rod (28). Several blades (35) are located inside the air box (21). Several evenly distributed air outlet pipes (27) are provided through the air box (21). A sphere (26) is fixedly provided at the lower end of the rotating rod (28). An arc plate (37) is assembled and connected on the sphere (26). A cross connecting rod (38) is fixedly provided at the lower end of the arc plate (37). A vertical rod (39) is fixedly provided at the other end of the cross connecting rod (38). The same rotating ring (40) is connected to the lower end of the vertical rod (39).

9. A method for connecting a back-contact battery in series according to claim 8, characterized in that, A rotating box (29) is fixedly installed at the lower end of the air blowing box (21). A rotating rod (28) rotates through the rotating box (29). A half-bevel gear (30) is fixedly installed on the rotating rod (28). A rotating rod (32) is symmetrically connected to the front and rear sides of the rotating box (29). A bevel gear (33) is fixedly installed on the rotating rod (32). The two bevel gears (33) are symmetrically arranged in front and behind. The bevel gear (33) meshes with the half-bevel gear (30). A gear (31) is fixedly installed on the side of the two rotating rods (32) that are close to each other. An arc-shaped through groove is opened on the rotating box (29). An arc-shaped rack (22) is slidably installed on the arc-shaped through groove. A through groove (34) is provided in the center of the arc-shaped rack (22). The rotating rod (28) passes through the through groove (34).

10. A method for connecting a back-contact battery in series according to claim 9, characterized in that, An arc-shaped connecting rod (23) is fixedly installed at the lower right end of the arc-shaped rack (22), and an arc box (24) is fixedly installed at the other end of the arc-shaped connecting rod (23). A circular groove is provided inside the arc box (24), and the rotating ring (40) is sealed and slidably connected to the circular groove. Several through holes are also provided on the rotating ring (40). Several arc-shaped protrusions (36) are fixedly installed on the sphere (26), and several arc-shaped grooves are provided inside the arc plate (37). Several arc-shaped protrusions (36) cooperate with several arc-shaped grooves. A storage box (8) is fixedly installed at the upper end of the spray box (7), and the recycling pipe (20) is connected to the storage box (8). A corrugated connecting pipe (15) is connected to the lower side of the storage box (8). The corrugated connecting pipe (15) passes through the sleeve cover (14) on the left side. A joint (25) is provided on the arc box (24), and the corrugated connecting pipe (15) is connected to the joint (25).

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