Preparation method of back contact battery assembly
By setting an insulating layer and conductive area on the busbar, and using solder paste to solder and copper-aluminum composite layers or aluminum busbars, the problems of exposed busbars and short circuits are solved, enabling high-efficiency power generation and low-cost production of back-contact battery modules.
Patent Information
- Application Number
- CN202511417705.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2026-01-13
AI Technical Summary
In traditional back-contact battery modules, exposed busbars reduce the power generation area, and the contact between the busbars and the solder strips makes them prone to short circuits. They are also prone to poor soldering and bubbles during welding, resulting in high material costs.
An insulating layer is set on the busbar, and conductive and adhesive areas are set in the areas where conductivity is required. Solder paste is used for soldering. Copper-aluminum composite layer or aluminum busbar is used. Circuit conductivity is achieved by laser welding or pre-fixing to avoid problems caused by pre-soldering.
Reduce material costs, avoid poor soldering and air bubbles, and hide the busbars on the back of the battery without taking up power generation area, thereby improving module power and aesthetics.
Smart Images
Figure CN121335262A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of solar cell preparation, and particularly relates to a preparation method of a back contact cell module. BACKGROUND
[0002] The back contact cell avoids shading on the front surface by moving all electrodes to the back surface, which can effectively improve the power generation efficiency of the module. However, the traditional back contact cell module still has the problem of exposed bus bars, that is, the bus bars need to be extended to the edge of the module for series connection, resulting in that the bus bars occupy the power generation area of the module and reduce the power generation power of the module, so that a full-screen scheme is needed to be developed to hide the bus bars on the back surface of the module.
[0003] In order to hide the bus bar, the bus bar needs to be directly fixed on the back surface of the cell string. Since the bus bar is perpendicular to the solder strip, directly contacting the bus bar with all solder strips will cause a short circuit problem, so the insulation problem of the bus bar needs to be solved. The existing scheme adopts a patterned adhesive film under the bus bar, and only the area needing conduction is exposed for welding.
[0004] However, the prior art has the following technical problems: (1) Since the bus bar is directly pressed on the solder strip and the cell, in order to avoid cell cracking, excessive pressure needs to be avoided, so that virtual welding problem is easily caused; (2) When the bus bar is welded, the surface temperature of the bus bar will be conducted to the cell, causing the adhesive film on the cell to be excessively melted before lamination, so that bubbles are easily generated in the area; (3) The bus bar needs to be tin-plated on the whole surface, which has a high material cost. SUMMARY
[0005] The present application aims to solve the above problems and provides a preparation method of a back contact cell module.
[0006] In a first aspect, the present application provides a preparation method of a back contact cell module, comprising: cutting the bus bar; the bus bar is provided with an insulating layer; the insulating layer can be provided on the bus bar by brushing, spraying, dipping or pasting and the like; The conductive area is provided on the bus bar, and the insulating layer of the conductive area is removed. A glue area is provided on the bus bar; and point-shaped or linear glue is sprayed on the glue area by spraying. Tin paste is provided on the conductive area of the bus bar; and the tin paste is dried or melted to obtain a pre-prepared bus bar; the melting point of the tin paste is less than the lamination temperature, so that the tin paste is welded during lamination.
[0007] The pre-prepared bus bar is vertically pre-fixed on the solder strip on the back surface of the back contact cell sheet. Laminate the back contact battery piece with pre-fixed busbar and the battery assembly auxiliary material, the battery assembly auxiliary material includes back adhesive film, glass or back plate and the like; the pre-fixed busbar is pressed on the solder strip and the battery piece on the back of the back contact battery string; the busbar and the solder strip surface of the back contact battery string need to be connected through tin paste welding to realize circuit conduction, and the back contact battery assembly is prepared.
[0008] Further, the preparation method of the back contact battery assembly, the material of the busbar is copper or copper-aluminum composite layer; when the material of the busbar is copper-aluminum composite layer, the copper is wrapped on one surface of the aluminum strip or wrapped on the surface of the aluminum strip, so that the busbar and the solder strip are contacted through the copper surface; the copper is used to realize the contact conduction of the busbar and the solder strip; by using the copper-aluminum composite layer structure, the material cost can be greatly reduced.
[0009] In the second aspect, the application provides another preparation method of the back contact battery assembly, comprising: The busbar is cut; the busbar is provided with an insulating layer; the insulating layer can be arranged on the busbar by brushing, spraying, dipping or pasting and the like; The conductive area is arranged on the busbar, which needs to be connected with the battery and the junction box, and the insulating layer of the conductive area is removed; The glue area is arranged on the busbar; the point-shaped or linear glue is sprayed on the glue area by spraying to prepare the pre-prepared busbar; The pre-prepared busbar is vertically pre-fixed on the solder strip on the back of the back contact battery piece; The back contact battery piece with pre-fixed busbar and the battery assembly auxiliary material are laminated; the pre-prepared busbar is pressed on the solder strip and the battery piece on the back of the back contact battery string; and the back contact battery assembly is prepared.
[0010] Further, the preparation method of the back contact battery assembly, the material of the busbar is aluminum; the solder strip adopts copper-aluminum composite layer, and the solder strip is contacted with the battery through the copper surface; the conductive area of the busbar is connected with the solder strip by laser welding.
[0011] Further, the preparation method of the back contact battery assembly in the first aspect and the second aspect, the busbar includes the access side busbar connected with the junction box; The two ends of the access side busbar are provided with lead-out wires through cutting; The access side busbar is in a triangular shape structure, wherein the part corresponding to no lead-out wire is the upper half, and the part corresponding to the lead-out wire is the lower half; The conductive area is arranged on the upper half part; and the glue area is arranged on the lower half part. By arranging the conductive area and the glue area separately, the glue does not affect the conductive area during the coating process, the electrical contact performance of the conductive area is effectively ensured, the pre-fixing effect is further improved by increasing the density of the dispensing or the length of the linear glue, and the preparation efficiency of the entire battery assembly is improved.
[0012] Further, the preparation method of the back contact battery assembly, the edge welding bus bar includes an edge welding bus bar connected with the welding strip at the edge of the battery; and the upper half part and the lower half part of the edge welding bus bar are arranged with a cutting slot. When the edge welding bus bar is connected with the welding strip at the edge of the battery, the connection part of the upper half part and the lower half part of the bus bar is disconnected due to the cutting slot, so that the lower half part of the bus bar does not exceed the edge of the battery after being bent.
[0013] Further, the preparation method of the back contact battery assembly, the insulating layer adopts insulating glue or insulating paint. By using insulating glue or insulating paint with an insulating level of H level and above, the insulating layer can not appear cracking, falling off and metamorphosis on the surface of the bus bar at ≥160℃, and can maintain good insulating effect.
[0014] Further, the preparation method of the back contact battery assembly, the conductive area is circular or rectangular; the diameter of the circular shape is 0.3-2mm; and the side length of the rectangular shape is 0.3-2mm. The thickness of the bus bar is 0.05-0.3mm, and the width is 8-50mm. The shape and size of the conductive area mainly consider the peeling force of the welding strip and the bus bar and the efficiency of laser removing the insulating paint. The larger the area of the conductive area, the higher the peeling force, and the reliability of the assembly is improved, but the corresponding laser removal area increases, and more peeling time is required.
[0015] Further, the preparation method of the back contact battery assembly, the glue area of the prefabricated bus bar adopts heat-sensitive glue or pressure-sensitive glue. By controlling the temperature or the applied pressure for glue bonding, the prefabricated bus bar is pre-fixed.
[0016] Further, the preparation method of the back contact battery assembly, the drying or melting of the tin paste is performed by one or more of electromagnetic heating, hot air heating, infrared heating, hot plate heating, microwave heating, and heating in a hot cavity.
[0017] The method for preparing a back-contact battery module according to the present invention involves prefabricating a busbar and pre-fixing it to the back of the battery cell, followed by lamination welding to achieve circuit conduction between the busbar and the battery cell. This method offers the following advantages: 1) The busbar uses a copper-aluminum composite material without tin plating, relying solely on solder paste in the conductive areas for lamination welding. This reduces material costs and eliminates the need for pre-lamination welding, avoiding issues such as microcracks, incomplete soldering, and air bubbles in the module caused by premature welding; 2) The busbar itself has an insulating layer, eliminating the need for pre-installed insulating materials and simplifying the production process; 3) Pre-fixing the busbar with tape or glue simplifies the production process; 4) The busbar is positioned on the back of the battery cell, not occupying the module's light-receiving area, thus improving module power and aesthetics; 5) Using aluminum busbars eliminates the need for tin plating and solder paste, and laser welding significantly reduces material costs. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the preparation method of the back contact battery assembly according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the back contact battery assembly structure according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the access-side busbar structure according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the edge-welded busbar structure according to an embodiment of the present invention; Figure 5 As in Embodiment 1 of the present invention Figure 2 The diagram shows the cross-section of the busbar AA. Figure 6 This is a schematic diagram of the access-side busbar structure according to Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the access-side busbar structure according to Embodiment 2 of the present invention; Figure 8 This is a schematic diagram of the bottom insulating layer structure of the access-side busbar according to Embodiment 2 of the present invention; Figure 9 As in Embodiment 3 of the present invention Figure 2 The diagram shows the cross-section of the busbar AA. Figure 10 This is a schematic diagram of the access-side busbar structure described in Embodiment 3 of the present invention; Figure 11 This is a schematic diagram of the preparation method of the back contact battery assembly according to Embodiment 3 of the present invention; Among them, 1-busbar, 2-back contact cell, 3-solder strip, 31-solder strip copper layer, 32-solder strip aluminum layer, 4-lead wire, 5-cut groove, 6-solder paste, 7-conductive area, 8-insulating layer, 9-pressure sensitive adhesive, 10-copper-aluminum composite layer, 11-aluminum strip, 12-copper strip. DETAILED DESCRIPTION
[0019] The preparation method of the back contact battery assembly is described in detail below with reference to the accompanying drawings and examples.
[0020] Example 1 The present example discloses a preparation method of a back contact battery assembly, as shown in the accompanying drawings, which specifically comprises the following steps: Figure 1 Step S1, cutting the bus bar 1 coated with an insulating layer 8 on one side; in the present example, the thickness of the bus bar 1 is 0.3 mm, and the width is 8 mm; the material of the insulating layer 8 is insulating glue of insulation grade H or above; the insulating layer 8 does not appear cracking, falling off, and metamorphic phenomena on the surface of the bus bar 1 at ≥160℃. In specific applications, the surface of the bus bar not provided with the insulating layer can be plated with tin to prevent oxidation of the bus bar. Step S2, setting a conductive area 7 on the bus bar 1 in the area where circuit conduction with the battery is required, and removing the insulating layer 8 of the conductive area 7; in the present example, the conductive area 7 is set as a rectangle with a length of 1 mm and a width of 1 mm; the insulating layer 8 is removed by laser etching.
[0021] Step S3, setting a glue area on the bus bar 1; spraying line-shaped pressure-sensitive adhesive 9 in the glue area by spraying.
[0022] Step S4, setting tin paste 6 on the conductive area 7 of the bus bar 1; and drying the tin paste 6 by electromagnetic heating to obtain a pre-prepared bus bar 1; the melting point of the tin paste 6 is less than the lamination temperature, so that it is welded during the lamination process. In the present example, the tin paste 6 is set in the form of point-shaped tin paste 6.
[0023] In the present example, the material of the bus bar 1 is a copper-aluminum composite layer 10; as shown in the accompanying drawings, the copper-aluminum composite layer 10 comprises a copper strip 12 and an aluminum strip 11 which are combined, and the insulating layer 8 is arranged on the copper strip 12; at present, such a composite layer can be prepared by cold rolling or hot rolling combination. The copper strip 12 is wrapped on one surface of the aluminum strip 11; the bus bar 1 is in contact with the solder strip 3 through the copper surface.
[0024] Figure 5 Step S5, as shown in the accompanying drawings, the pre-prepared bus bar 1 is vertically pre-fixed on the solder strip 3 on the back surface of the back contact battery piece 2; in the present example, the pressure-sensitive adhesive 9 is used for pre-fixing; the pre-prepared bus bar 1 is placed at a specific position on the back surface of the back contact battery piece 2, and the bus bar 1 is gently pressed to make the pressure-sensitive adhesive 9 generate adhesion, so that the pre-prepared bus bar 1 is pre-fixed on the back contact battery piece 2.
[0025] Figure 2
[0026] Step S6, laminating the back contact battery piece 2 pre-fixed with the bus bar 1 and the battery assembly auxiliary materials, including back adhesive film, glass or back plate, etc.; the pre-made bus bar 1 is pressed on the solder strip 3 on the back of the back contact battery string and the battery piece; the bus bar 1 and the surface of the solder strip 3 of the back contact battery string need to be conductive area through the tin paste 6 welding to realize the circuit conduction, and the back contact battery assembly is prepared.
[0027] In the embodiment of the present disclosure, for the access side bus bar 1 which needs to access the junction box, as shown in Figure 3 、 Figure 5 , when cutting, the two ends of the access side bus bar 1 are cut out to form the lead-out wire 4; the access side bus bar 1 is in a triangular shape, wherein the part corresponding to the lead-out wire 4 is the upper half, and the part corresponding to the lead-out wire 4 is the lower half; the conductive area 7 is arranged on the upper half; and the glue area is arranged on the lower half.
[0028] In the embodiment of the present disclosure, the edge welding bus bar 1 which is connected with the solder strip 3 at the edge of the battery, as shown in Figure 4 、 Figure 6 , cutting is performed on the upper half and the lower half to form the cutting groove 5. When the edge welding bus bar 1 is connected with the solder strip 3 at the edge of the battery, the upper half and the lower half of the bus bar 1 are partially disconnected due to the cutting groove 5, so that when the lower half of the bus bar 1 is bent, it will not exceed the edge of the battery.
[0029] In specific applications, for the drying or melting method of the tin paste 6, the implementer can select one or a combination of electromagnetic heating, hot air heating, infrared heating, hot plate heating, microwave heating, and heating in a hot cavity according to actual conditions.
[0030] Embodiment Two Based on the above embodiment one, the present embodiment discloses a preparation method of a back contact battery assembly, as shown in Figure 7 , which is different from the embodiment one in that both surfaces of the bus bar 1 in the present embodiment are coated with an insulating layer 8, and the preparation method comprises the following steps: Step S1, cutting the bus bar 1 coated with the insulating layer 8 on both surfaces; in the present embodiment, the thickness of the bus bar 1 is 0.15 mm, and the width is 25 mm; the insulating layer 8 is made of insulating glue of insulating grade H or above; and when the temperature is greater than or equal to 160 DEG C, the insulating layer 8 does not appear cracking, falling off, and metamorphism on the surface of the bus bar 1.
[0031] In specific applications, the bus bar 1 placed on the surface of the battery can reduce the thickness by increasing the width of the bus bar 1, while keeping the total resistance unchanged, which is also helpful to prevent the battery from cracking.
[0032] Step S2, as shown in Figure 7 ,Figure 8 As shown, conductive areas 7 are provided on the busbar 1 in the area where it needs to be connected to the battery and at the connection point with the junction box, and the insulating layer of the conductive areas 7 is removed; in this embodiment, the conductive areas 7 are set as rectangles, the rectangles are 1.5mm long and 1mm wide; the insulating layer 8 is removed by laser etching.
[0033] Step S3: Set an adhesive area on the busbar 1; spray linear pressure-sensitive adhesive 9 onto the adhesive area by spraying.
[0034] Step S4: Solder paste 6 is applied to the conductive area 7 of the busbar 1; and the solder paste 6 is dried by electromagnetic heating to obtain the prefabricated busbar 1; the melting point of the solder paste 6 is lower than the lamination temperature, so that it can be soldered during the lamination process. In this embodiment, the solder paste 6 is applied by coating dotted solder paste 6.
[0035] In this embodiment, the busbar 1 is made of a copper-aluminum composite layer 10. Similar to Embodiment 1, the copper-aluminum composite layer 10 comprises a composite-formed copper strip 12 and an aluminum strip 11, with the insulating layer 8 disposed on the copper strip 12. Currently, this composite layer can be manufactured by cold rolling or hot rolling. The copper strip 12 is wrapped around one side of the aluminum strip 11, allowing the busbar 1 and the solder strip 3 to contact each other through the copper surface.
[0036] Step S5, as follows Figure 2 As shown, the prefabricated busbar 1 is vertically pre-fixed to the solder strip 3 on the back of the back contact cell 2; in this embodiment, pressure-sensitive adhesive 9 is used for pre-fixation; the prefabricated busbar 1 is placed at a specific position on the back of the back contact cell 2, and the busbar 1 is lightly pressed to generate adhesive force in the pressure-sensitive adhesive 9, thereby pre-fixing the prefabricated busbar 1 to the back contact cell 2.
[0037] Step S6: Lamination is performed on the back contact battery cell 2 with the pre-fixed busbar 1 and the battery module auxiliary materials, including back adhesive film, glass or back plate, etc.; the pre-made busbar 1 is pressed onto the solder strip 3 on the back of the back contact battery string and the battery cell; the areas on the surface of the busbar 1 and the solder strip 3 of the back contact battery string that need to be conductive are soldered with solder paste 6 to achieve circuit conduction, thereby obtaining the back contact battery module.
[0038] In this embodiment of the disclosure, for the access-side busbar 1 that needs to be connected to the junction box, such as Figure 3 As shown, during the cutting process, the two ends of the access side busbar 1 are cut to produce lead wires 4; the access side busbar 1 has a triangular structure, wherein the part without lead wires 4 is the upper half, and the part corresponding to lead wires 4 is the lower half; the conductive area 7 is located in the upper half; and the adhesive area is located in the lower half.
[0039] In the embodiment of the present disclosure, the edge welding busbar 1 in communication with the solder strip 3 at the edge of the battery, as shown in Figure 4 、 Figure 7 is provided with a cutting groove 5 between the upper half and the lower half. When the edge welding busbar 1 is in communication with the solder strip 3 at the edge of the battery, the upper half and the lower half of the busbar 1 are partially disconnected at the cutting groove 5, so that the lower half of the busbar 1 will not exceed the edge of the battery after being bent.
[0040] In specific applications, the drying or melting method of the tin paste 6 can be selected by the implementer according to the actual situation, such as electromagnetic heating, hot air heating, infrared heating, hot plate heating, microwave heating, and heating in a hot cavity.
[0041] Embodiment three The present disclosure discloses another preparation method of a back contact battery assembly, as shown in Figure 11 , which specifically comprises the following steps: Step S1, cutting the busbar 1 coated with an insulating layer 8 on one side; in the embodiment, the thickness of the busbar 1 is 0.1 mm, and the width is 35 mm; the insulating layer 8 is an insulating adhesive with an insulating grade of H level or above; the insulating layer 8 does not appear cracking, falling off, and metamorphic phenomena on the surface of the busbar 1 at ≥160℃.
[0042] Step S2, setting a conductive area 7 on the busbar 1 in the area required for circuit conduction with the battery, and removing the insulating layer 8 of the conductive area 7; in the embodiment, the conductive area 7 is set as a rectangle with a length of 1.5 mm and a width of 0.5 mm; the insulating layer 8 is removed by laser etching.
[0043] Step S3, setting a glue area on the busbar 1; spraying point-shaped pressure-sensitive adhesive 9 on the glue area by spraying to obtain a pre-prepared busbar 1.
[0044] In the embodiment of the present disclosure, as shown in Figure 9 , the material of the busbar 1 is aluminum; the surface of the busbar 1 is not plated with tin; the solder strip 3 adopts a copper-aluminum composite layer 10, including a solder strip aluminum layer 32 and a solder strip copper layer 31, and the solder strip 3 is in contact with the battery through the solder strip copper layer 31; the conductive area 7 of the busbar 1 is connected with the solder strip 3 by laser welding.
[0045] Step S4, as shown in Figure 2 , the pre-prepared busbar 1 is vertically pre-fixed on the solder strip 3 at the back of the back contact battery piece 2; in the embodiment of the present disclosure, pressure-sensitive adhesive 9 is used for pre-fixing; the pre-prepared busbar 1 is placed at a specific position at the back of the back contact battery piece 2, and the busbar 1 is lightly pressed to make the pressure-sensitive adhesive 9 generate adhesion, so that the pre-prepared busbar 1 is pre-fixed on the back contact battery piece 2.
[0046] Step S5: The back contact battery cell 2 with the pre-fixed busbar 1 and the battery module auxiliary materials are laminated. The battery module auxiliary materials include back adhesive film, glass or back plate, etc. The pre-made busbar 1 is pressed onto the welding strip 3 on the back of the back contact battery string and the battery cell, and its conductive area 7 is welded with laser to obtain the back contact battery module.
[0047] In this embodiment of the disclosure, for the access-side busbar 1 that needs to be connected to the junction box, such as Figure 10 As shown, during the cutting process, the two ends of the access side busbar 1 are cut to produce lead wires 4; the access side busbar 1 has a triangular structure, wherein the part without lead wires 4 is the upper half, and the part corresponding to lead wires 4 is the lower half; the conductive area 7 is located in the upper half; and the adhesive area is located in the lower half.
[0048] In this embodiment, the edge-welded busbar 1, which is connected to the outermost edge of the battery, has a cutting groove 5 cut into its upper and lower halves. When the edge-welded busbar 1 is connected to the outermost edge of the battery, the connection between the upper and lower halves of the busbar 1 is partially broken by the cutting groove 5, so that the lower half of the busbar 1 will not extend beyond the edge of the battery after bending.
Claims
1. A method for preparing a back-contact battery assembly, characterized in that... include: The busbar is cut; an insulating layer is provided on the busbar; Conductive areas are provided on the busbar in the areas where it needs to be connected to the battery and at the connection points with the junction box, and the insulation layer of the conductive areas is removed. An adhesive area is provided on the busbar; dotted or linear adhesive is sprayed onto the adhesive area by spraying. Solder paste is applied to the conductive area of the busbar, and the solder paste is dried or melted to obtain a prefabricated busbar; The prefabricated busbar is vertically pre-fixed to the solder strip on the back of the back contact cell; The back contact battery cells with pre-fixed busbars and battery module auxiliary materials are laminated together; the pre-made busbars are pressed onto the solder strips and battery cells on the back of the back contact battery string; thus, a back contact battery module is obtained.
2. The method for preparing the back contact battery assembly according to claim 1, characterized in that: The busbar is made of copper or a copper-aluminum composite layer. When the busbar is made of a copper-aluminum composite layer, copper is wrapped around one or all of the aluminum strip surface, and the busbar and the solder strip make contact through the copper surface.
3. A method for preparing a back-contact battery assembly, characterized in that... include: The busbar is cut; an insulating layer is provided on the busbar; Conductive areas are provided on the busbar in the areas where it needs to be connected to the battery and at the connection points with the junction box, and the insulation layer of the conductive areas is removed. An adhesive area is provided on the busbar; dotted or linear adhesive is sprayed onto the adhesive area to obtain a prefabricated busbar. The prefabricated busbar is vertically pre-fixed to the solder strip on the back of the back contact cell; The back contact battery cells with pre-fixed busbars and battery module auxiliary materials are laminated together; the pre-made busbars are pressed onto the solder strips and battery cells on the back of the back contact battery string; thus, a back contact battery module is obtained.
4. The method for preparing the back contact battery assembly according to claim 3, characterized in that: The busbar is made of aluminum; the solder strip is a copper-aluminum composite layer, and the solder strip contacts the battery through the copper surface; the conductive area of the busbar is connected to the solder strip by laser welding.
5. The method for preparing the back contact battery assembly according to any one of claims 1-4, characterized in that: The busbar includes an access-side busbar connected to the junction box; Both ends of the access-side busbar are cut and have lead wires installed; The access-side busbar has a triangular structure, with the part without a lead wire being the upper half and the part with a lead wire being the lower half. The conductive area is located in the upper half; the adhesive area is located in the lower half.
6. The method for preparing the back contact battery assembly according to claim 5, characterized in that: The access-side busbar includes an edge-welded busbar that is connected to the solder strip at the outermost edge of the battery; the upper and lower halves of the edge-welded busbar are provided with a cutting groove by cutting.
7. The method for preparing the back contact battery assembly according to claim 6, characterized in that: The insulating layer is made of insulating adhesive or insulating varnish.
8. The method for preparing the back contact battery assembly according to claim 6, characterized in that: The conductive area is circular or rectangular; the diameter of the circle is 0.3-2mm; the side length of the rectangle is 0.3-2mm; the thickness of the busbar is 0.05-0.3mm and the width is 8-50mm.
9. The method for preparing the back contact battery assembly according to claim 6, characterized in that: The adhesive area of the prefabricated busbar is made of heat-sensitive adhesive or pressure-sensitive adhesive.
10. The method for preparing the back contact battery assembly according to claim 6, characterized in that: The method of drying or melting solder paste is one or more of the following mixed heating methods: electromagnetic heating, hot air heating, infrared heating, hot plate heating, microwave heating, and heating by sending it into a hot cavity.