Welding method of solar cell module

Abstract

A welding method of a solar cell module belongs to the field of solar cell modules, and is characterized by comprising the following steps of: coating high-temperature alloy solder on a solder strip in the solar cell module or arranging high-temperature solder paste on a cell piece; secondary high-temperature heating is carried out on the solar cell module in the lamination process or after lamination treatment, and welding between the welding strip and the cell piece is achieved by melting the high-temperature alloy welding flux on the welding strip or the high-temperature solder paste on the cell piece. By adding a heating process on the lamination temperature, the problems that welding spots are not firm and are easy to fall off in the existing welding process can be effectively solved; meanwhile, the welding method can heat the whole string or the whole assembly at the same time, energy consumption is low, efficiency is high, and energy conservation and high efficiency are achieved; and tin-lead solder paste or tin-silver-copper high-melting-point solder paste can be compatible, solder paste with various melting points and components can be matched according to battery paste and solder strip surface materials, the design requirements of different assemblies are met, the application range is wide, and the method is suitable for application and popularization.

Description

Technical Field

[0001] The invention belongs to the field of solar cell components, and in particular relates to a welding method for solar cell components. Background Art

[0002] During the preparation of photovoltaic modules, the various layers of components that make up the photovoltaic modules need to be laminated by a laminator. In the production process of some IBC modules, insulating glue is printed on some of the grid lines of the battery, causing the main grid or auxiliary grid to be welded to be recessed in the gap of the insulating glue and unable to form a good contact with the welding strip. Therefore, solder paste is printed at the welding position to make the solder point protrude from the battery surface and easier to weld with the welding strip. The existing lamination welding process uses low-temperature alloy-coated welding strips or low-temperature alloy-component solder paste. During the lamination process, since the melting point of the alloy on the welding strip is lower than the lamination temperature, the alloy coating is fully dissolved during the lamination process and forms an intermetallic compound with the slurry on the battery. After cooling, the welding is completed.

[0003] Since the lamination process takes a long time, the internal temperature of the component exceeds the melting point of the alloy for more than 5-10 minutes, and a large amount of intermetallic compounds are generated, which affects the conductivity between the welding strip and the battery grid line. In addition, a large amount of intermetallic compounds are generated, and a large amount of slurry is required to combine with the solder at high temperature. If a large amount of slurry is combined, the slurry will fall off the battery silicon wafer and form over-welding; on the other hand, low-temperature solder generally uses Sn42Bi58 with a higher bismuth content (melting point 138°C) or Sn43Pb43BI14 with a slightly lower bismuth content (melting point 153°C). Since the alloy solder contains a high amount of bismuth, Bi is easily enriched in a long-term high-temperature melting environment to form a brittle structure, resulting in a weak solder joint. Even if a welding structure is formed, its peeling force is small, and it is easy to fall off the pad during the entire life cycle of the component. Summary of the invention

[0004] The present invention aims to solve the above problems and provides a welding method for a solar cell assembly.

[0005] The method for welding a solar cell module of the present invention comprises coating a high-temperature alloy solder on a welding strip in the solar cell module or placing a high-temperature solder paste on a cell sheet; performing secondary high-temperature heating on the solar cell module during or after lamination, and achieving welding between the welding strip and the cell sheet by melting the high-temperature alloy solder on the welding strip or the high-temperature solder paste on the cell sheet.

[0006] Furthermore, in the welding method of the solar cell module described in the present invention, the method of performing secondary high-temperature heating on the solar cell module during the lamination process is as follows: a secondary high-temperature heating chamber is added behind the heating chamber of the lamination equipment; first, the solar cell module is heated for the first time by the heating chamber of the lamination equipment to complete the lamination of the layers constituting the solar cell module; then, secondary heating is performed by the secondary high-temperature heating chamber of the lamination equipment to complete the welding between the welding ribbon and the battery cell.

[0007] By adding secondary high-temperature heating in the laminator, unlike the traditional stringer, welding is not done on the stringer. It is only necessary to stick the soldering ribbon and the battery together, and the welding process is placed in the laminator. This method can eliminate the battery warping caused by the large difference in thermal expansion coefficient between the soldering ribbon and the battery cell when the stringer is stringed, save energy consumption in the component manufacturing process, and complete the welding between the soldering ribbon and the battery cell at low cost and high efficiency.

[0008] Furthermore, in the welding method of the solar cell module described in the present invention, the method of performing secondary high-temperature heating on the solar cell module during the lamination process is as follows: one side of the heating chamber of the lamination equipment is set as transparent glass; an infrared heating lamp is set on the side of the heating chamber where the transparent glass is set; first, the solar cell module is heated for the first time by the heating chamber of the lamination equipment to complete the lamination of the layers constituting the solar cell module; then, a secondary heating is performed by the infrared heating lamp to complete the welding between the welding ribbon and the battery cell.

[0009] Furthermore, in the welding method of the solar cell module described in the present invention, the method of performing secondary high-temperature heating on the solar cell module after lamination is to set an infrared heating component at the discharge end of the lamination equipment; when the solar cell module completes the first heating in the lamination equipment and is transmitted to the external chain, it is heated for the second time by the infrared heating component to complete the welding between the welding ribbon and the battery cell.

[0010] Furthermore, in the soldering method of the solar cell module of the present invention, the melting point of the high temperature alloy solder or high temperature solder paste is between 150°C and 232°C; the composition of the high temperature alloy solder or high temperature solder paste includes one or more alloys of tin, lead, bismuth, silver, silver, and indium elements. Furthermore, in the welding method of the solar cell module of the present invention, the heating chamber of the laminating equipment heats the solar cell module to a temperature of 130-150°C; and the temperature of the secondary high-temperature heating is 200-250°C.

[0011] The welding method of the solar cell module of the present invention can be completed in a vacuum environment, with rapid heating and cooling, good welding quality, and is suitable for busbar-free / 0BB technology with many solder joints; the welding method of the present invention adds a heating process to the lamination temperature, which can effectively solve the problem that the solder joints are not firm and easy to fall off in the existing welding process; at the same time, the welding method can heat and heat the entire string or the entire block of components at the same time, with low energy consumption, high efficiency, energy saving and high efficiency; it can be compatible with tin-lead solder paste or tin-silver-copper high-melting point solder paste, and can be matched with various melting points and composition solder pastes according to the battery slurry and the surface material of the solder strip to meet the design requirements of different components, with a wide range of applications and suitable for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of a welding process device for a solar cell module according to the first embodiment of the present invention; Figure 2 This is a schematic diagram of a welding process device for a solar cell module according to the second embodiment of the present invention; Among them, 1-photovoltaic backplane, 2-photovoltaic film, 3-battery string, 4-photovoltaic glass, 5-transparent glass, 6-infrared heating lamp, 7-lower cavity inlet and outlet holes, 8-elastic film, 9-upper cavity inlet and outlet holes, and 10-heating plate. DETAILED DESCRIPTION

[0013] The welding method of the solar cell module of the present invention is described in detail below through the accompanying drawings and embodiments.

[0014] Embodiment 1 This embodiment discloses a method for welding a solar cell module, which includes coating a high-temperature alloy solder on a welding strip in the solar cell module; performing secondary high-temperature heating on the solar cell module during lamination to weld the welding strip to the cell sheet.

[0015] In the embodiments of the present disclosure, Figure 1 As shown, the specific method of performing secondary high-temperature heating on the solar cell assembly during the lamination process is: set one side of the heating chamber of the laminating equipment as transparent glass 5; set infrared heating lamp 6 on the side where the transparent glass 5 is set in the heating chamber; firstly, the solar cell assembly is heated for the first time by the heating chamber of the laminating equipment to complete the lamination of the layers constituting the solar cell assembly; then, secondary heating is performed by the infrared heating lamp 6 to complete the welding between the welding ribbon and the battery cell. The alloy composition of the high-temperature alloy solder in the embodiment of the present disclosure is Sn63Pb37. The heating chamber of the laminating equipment heats the solar cell assembly at a temperature between 130-150°C; the temperature of the secondary high-temperature heating is between 200-250°C.

[0016] The welding method of the solar cell assembly described in this embodiment specifically includes the following steps: Step 1, laying of stacked components; according to the composition of the solar cell component, the following steps are completed in sequence: laying of the bottom plate / photovoltaic glass 4 - laying of the lower surface photovoltaic film 2 (EVA / POE) - laying of the battery string 3 and welding with the welding strip - laying of the upper surface photovoltaic film 2 (EVA / POE) - laying of the photovoltaic back sheet 1; the welding strip is coated with high temperature alloy solder; an elastic film 8 (rubber mold) is arranged between the photovoltaic back sheet 1 and the upper chamber of the laminator; Step 2, vacuuming; transporting the solar cell assembly after the stacking assembly is completed to the laminator cavity, and vacuuming the upper and lower chambers of the laminator simultaneously through the upper cavity inlet and outlet holes 9 and the lower cavity inlet and outlet holes 7; Step 3, heating the stacked assembly; the upper and lower chambers of the laminator are kept in vacuum to heat the stacked assembly; Step 4, secondary heating: irradiate the stacked components to a higher set temperature by infrared heating lamps 6. For single-glass components, irradiate from the light-receiving side of the components; for double-glass components, irradiate from the back of the components; Step 5, pressurization: After the stacked components are heated for the second time, the upper chamber of the laminator gradually cancels the vacuum and returns to normal pressure; at this time, the lower chamber of the laminator is still in a vacuum state, so that the upper chamber exerts an atmospheric pressure on the laminated components in the lower chamber; Step 6, heat preservation and assimilation: constant temperature curing at the curing temperature; Step 7, cooling: After constant temperature curing, the laminator is evacuated from the heat source, and the lower chamber of the laminator is still in a vacuum state; cycle cooling is performed to cancel the vacuum in the lower chamber; Step 8, cooling: After lamination, the solar cell components are transported to the conveying mechanism and the fan is turned on to cool to room temperature to complete the component lamination process.

[0017] In a specific application, the inventor can arrange the infrared heating lamp tube 6 behind the heating chamber of the laminator, that is, add a secondary high-temperature heating chamber behind the heating chamber of the laminating equipment; firstly, the solar cell module is heated for the first time by the heating chamber of the laminating equipment to complete the lamination of the layers constituting the solar cell module; then, the secondary heating is performed by the secondary high-temperature heating chamber of the laminating equipment to complete the welding between the soldering ribbon and the battery cell.

[0018] By adding secondary high-temperature heating in the laminator, unlike the traditional stringer, welding is not done on the stringer. It is only necessary to stick the soldering ribbon and the battery together, and the welding process is placed in the laminator. This method can eliminate the battery warping caused by the large difference in thermal expansion coefficient between the soldering ribbon and the battery cell when the stringer is stringed, save energy consumption in the component manufacturing process, and complete the welding between the soldering ribbon and the battery cell at low cost and high efficiency.

[0019] Embodiment 2 This embodiment discloses a method for welding a solar cell module, which includes coating a high-temperature alloy solder on a welding strip in the solar cell module; performing secondary high-temperature heating on the solar cell module after lamination, and welding the welding strip to the cell sheet.

[0020] In the embodiments of the present disclosure, Figure 2 As shown, the specific method of performing secondary high-temperature heating on the solar cell assembly during the lamination process is: an infrared heating assembly is set at the discharge end of the laminating equipment; when the solar cell assembly completes the first heating through the heating plate 10 in the laminating equipment and is transmitted to the external chain, the infrared heating assembly is used for secondary heating to complete the welding between the high-temperature alloy welding strip and the battery cell. In the embodiment disclosed in the present invention, the alloy composition of the high-temperature alloy solder is Sn / Ag0.3 / Cu0.7. The heating chamber of the laminating equipment heats the solar cell assembly at a temperature between 130-150°C; the temperature of the secondary high-temperature heating is between 200-250°C; in this embodiment, the infrared heating assembly uses an infrared heating lamp 6.

[0021] The welding method of the solar cell assembly described in this embodiment specifically includes the following steps: Step 1, laying of stacked components; according to the composition of the solar cell component, the following steps are completed in sequence: laying of the bottom plate / photovoltaic glass 4 - laying of the lower surface photovoltaic film 2 (EVA / POE) - laying of the battery string 3 and welding with the welding strip - laying of the upper surface photovoltaic film 2 (EVA / POE) - laying of the photovoltaic back sheet 1; the welding strip is coated with high temperature alloy solder; an elastic film 8 (rubber mold) is arranged between the photovoltaic back sheet 1 and the upper chamber of the laminator; Step 2, vacuuming; transporting the solar cell components with completed stacking components to the laminator cavity, and vacuuming the upper and lower chambers of the laminator at the same time; Step 3, heating the stacked assembly; the upper and lower chambers of the laminator are kept in vacuum to heat the stacked assembly; Step 4, pressurization: the upper chamber of the laminator gradually cancels the vacuum and returns to normal pressure; at this time, the lower chamber of the laminator is still in a vacuum state, so that the upper chamber exerts an atmospheric pressure on the laminated parts in the lower chamber; Step 5, heat preservation and assimilation: constant temperature curing at the curing temperature; Step 6, secondary heating; when the solar cell assembly is transmitted from the laminator to the external chain, it is scanned by the infrared heating lamp 6 to achieve heating to the set temperature for secondary heating; Step 7, cooling: After constant temperature curing, the laminator is evacuated from the heat source, and the lower chamber of the laminator is still in a vacuum state; cycle cooling is performed to cancel the vacuum in the lower chamber; Step 8, cooling: After lamination, the solar cell components are transported to the conveying mechanism and the fan is turned on to cool to room temperature to complete the component lamination process.

[0022] The welding method described in this embodiment uses reliable high-temperature solder materials, and through short-term temperature increase welding, a thin layer of intermetallic compound is formed between the solder and the welded material "sintered photovoltaic silver paste" to form a good weld. It is a new component welding method with low power consumption and high efficiency.

[0023] In specific applications, technicians can also set the solder paste between the cell and the solder strip in the solar cell module to a high-temperature alloy solder paste with the same composition as the high-temperature alloy solder coated on the solder strip according to specific circumstances. The rest of the welding process is the same as the above embodiment, and the same welding effect can be obtained.

Claims

1. A method for welding a solar cell assembly, characterized in that: The soldering ribbon in the solar cell module is coated with high-temperature alloy solder or high-temperature solder paste is placed on the cell. The solar cell module is subjected to secondary high-temperature heating during the lamination process or after the lamination process, and the soldering ribbon and the cell are welded by melting the high-temperature alloy solder on the soldering ribbon or the high-temperature solder paste on the cell.

2. The method for welding a solar cell assembly according to claim 1, characterized in that: The method of performing secondary high-temperature heating on the solar cell assembly during the lamination process is to add a secondary high-temperature heating chamber behind the heating chamber of the lamination equipment; firstly, the solar cell assembly is heated for the first time by the heating chamber of the lamination equipment to complete the lamination of the layers constituting the solar cell assembly; then, secondary heating is performed by the secondary high-temperature heating chamber of the lamination equipment to complete the welding between the welding ribbon and the battery cell.

3. The method for welding a solar cell assembly according to claim 1, characterized in that: The method of performing secondary high-temperature heating on the solar cell assembly during the lamination process is as follows: one side of the heating chamber of the lamination equipment is set as transparent glass; an infrared heating lamp is set on the side of the heating chamber where the transparent glass is set; firstly, the solar cell assembly is heated for the first time by the heating chamber of the lamination equipment to complete the lamination of the layers constituting the solar cell assembly; then, secondary heating is performed by the infrared heating lamp to complete the welding between the welding ribbon and the battery cell.

4. The method for welding a solar cell assembly according to claim 1, characterized in that: The method of performing secondary high-temperature heating on the solar cell assembly after lamination is to set an infrared heating assembly at the discharge end of the lamination equipment; when the solar cell assembly completes the first heating in the lamination equipment and is transmitted to the external chain, it is heated for the second time by the infrared heating assembly to complete the welding between the welding ribbon and the battery cell.

5. The method for welding a solar cell module according to any one of claims 1 to 4, characterized in that: The melting point of the high temperature alloy solder or high temperature solder paste is between 150°C and 232°C; The components of the high-temperature alloy solder or high-temperature solder paste include one or more alloys of tin, lead, bismuth, silver, silver, and indium.

6. The method for welding a solar cell assembly according to claim 5, characterized in that: The heating chamber of the laminating equipment heats the solar cell components to a temperature of 130-150°C; The temperature of the secondary high-temperature heating is 200-250°C.

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