A back contact solar cell interconnection method

Abstract

The present application relates to the technical field of solar cells, in particular to a back contact solar cell interconnection method, comprising: staggered arrangement of positive and negative fine grid lines on the back of a cell; printing a conical insulating glue on the negative fine grid line at the position corresponding to the positive solder strip, and printing a conductive glue on the positive fine grid line; printing a conical insulating glue on the positive fine grid line at the position corresponding to the negative solder strip, and printing a conductive glue on the negative fine grid line; printing a separation glue at the position corresponding to the positive and negative solder strips at the edge of the cell; staggered arrangement of positive and negative solder strips on the conductive glue; and then performing a lamination and soldering process. The present application realizes connection by printing a conductive glue between fine grid lines, removes the traditional main grid line connection, and reduces the amount of silver paste; and a solder strip of a specific shape can be directly laid on the conductive glue for pre-solidification, ensuring sufficient connection of the solder strip with the fine grid through the conductive glue, and effectively solving the problem of virtual soldering in the later lamination.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a back contact solar cell interconnection method. BACKGROUND

[0002] The improvement of photoelectric conversion efficiency is the focus of solar technology. The back contact solar technology is to print the positive and negative grids on the back surface of the cell through special technical means, forming a cross arrangement of positive and negative electrodes on the back surface of the cell. This technology can effectively improve the efficiency of solar cells and make solar cells more beautiful, while being compatible with PERC, TOPCON, HJT cells and other technologies.

[0003] The prior art back contact solar cell, as shown in the accompanying drawings, Fig. 1-2 The positive and negative fine grids are horizontally cross arranged on the back surface of the cell, and the positive and negative main grids are vertically cross arranged. Rectangular insulating glue is printed on the fine grids on both sides of the positive main grid, and rectangular insulating glue is printed on the fine grids on both sides of the negative main grid. After tin paste is printed on the positive and negative main grid PAD points, flat solder strips are laid and hot soldering is performed, or solidified glue is printed at the PAD point position to fix the solder strips, and then laminated soldering is performed. However, the above process has the problems of large silver paste consumption, gap between the solder strip and the grid line leading to insulation virtual welding, and direct pressure impact of the solder strip on the cell causing its rupture. Based on this, a back contact solar cell interconnection method is proposed. SUMMARY

[0004] To overcome the shortcomings of the prior art, the present application provides a back contact solar cell interconnection method, which removes the main grid to reduce the amount of silver paste used and ensures the full connection of the special-shaped solder strip with the fine grid through conductive glue, effectively solving the problem of virtual welding in the later laminating process.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a back contact solar cell interconnection method, comprising the following steps,

[0006] (1) performing printing and sintering treatment on the back surface of the cell to form intermittent positive and negative fine grid lines, the positive and negative fine grid lines being staggered distributed;

[0007] (2) printing conical insulating glue on the negative fine grid line at the position corresponding to the positive solder strip, and printing conductive glue on the positive fine grid line; printing conical insulating glue on the positive fine grid line at the position corresponding to the negative solder strip, and printing conductive glue on the negative fine grid line;

[0008] (3) printing isolation glue at the positions corresponding to the positive and negative solder strips at the edge of the cell;

[0009] (4) staggered laying the positive and negative solder strips on the conductive glue, and heating and curing to pre-fix the positive and negative solder strips on the cell;

[0010] (5) then carry out laminated welding treatment, realize the alloying connection of the positive electrode welding strip and the fine grid line, the negative electrode welding strip and the negative electrode fine grid line.

[0011] Preferably, in the step (2), the conical insulation glue is silica gel or epoxy glue, the hardness is 5-7H, the length is 2-3mm, and the thickness is 30-40μm.

[0012] Preferably, in the step (2), the conductive glue adopts silica gel, epoxy or acrylic system, and a circular plastic particle plated with conductive metal on the surface is used as a conductive carrier.

[0013] Preferably, the diameter of the circular plastic particle is 5-10μm, and the conductive metal is silver, nickel or copper.

[0014] Preferably, the length of the conductive glue is 1-3mm, and the width is 0.4-0.8mm.

[0015] Preferably, in the step (3), the isolation glue is silica gel or epoxy glue, the hardness is 3-5H, the length is 1-3mm, the width is 1-2mm, and the thickness is 10-30μm.

[0016] Preferably, in the step (4), the positive electrode welding strip and the negative electrode welding strip both adopt a special-shaped welding strip; the width of the special-shaped welding strip is 0.6-0.8mm, the thickness is 0.2-0.25mm, the cross section is trapezoidal, the upper surface is a plane, and a plurality of grooves are arranged at intervals on the lower surface.

[0017] Preferably, the width of the groove is 10-20μm, and the depth is 5-10μm.

[0018] Preferably, in the step (4), the temperature of the heating and curing is 130-140℃, and the time is 10-20s.

[0019] The application provides a back contact solar cell interconnection method, and has the following beneficial effects compared with the prior art:

[0020] The application realizes the connection by printing the conductive glue between the fine grid lines, removes the traditional main grid line connection, greatly reduces the amount of silver paste, and directly lays the welding strip with a specific shape on the conductive glue for pre-curing, so that the welding strip is fully connected with the fine grid through the conductive glue, and the problem of virtual welding in the later laminating process is effectively solved.

[0021] The application prints the isolation glue on the edge of the cell sheet, and in the laminated welding process, the direct pressure impact of the welding strip on the cell sheet can be slowed down, the buffering effect is achieved, and the risk of cell sheet breakage is reduced.

[0022] The present application uses a special-shaped solder strip, and when laminating, the adhesive film flows on the trapezoidal section, which can reduce the horizontal shear force and reduce the risk of solder strip deviation; meanwhile, a groove is arranged on the bottom surface of the special-shaped solder strip, which is combined with the conductive adhesive at the connection of the fine grid, so as to ensure the close connection of the solder strip and the conductive adhesive and avoid the flow of the adhesive film into the gap between the solder strip and the conductive adhesive during laminating, thereby causing insulation. BRIEF DESCRIPTION OF DRAWINGS

[0023] The drawings described herein are used to provide further understanding of the present application, constitute a part of the present application, and the illustrative embodiments of the present application and the description thereof are used to explain the present application and do not constitute improper limitations on the present application. In the drawings:

[0024] Fig. 1 It is a schematic diagram of the interconnection of the back contact battery in the prior art;

[0025] Fig. 2 It is a schematic diagram of the interconnection of the back contact battery in the prior art; Fig. 1 It is an enlarged schematic diagram of part A in the prior art;

[0026] Fig. 3 It is a schematic diagram of the interconnection of the back contact battery in the prior application;

[0027] Fig. 4 It is a schematic diagram of the interconnection of the back contact battery in the prior application; Fig. 3 It is an enlarged schematic diagram of part B in the prior application;

[0028] Fig. 5 It is a schematic diagram of the front and side of the special-shaped solder strip in the present application. DETAILED DESCRIPTION

[0029] The following embodiments are used to illustrate the implementation of the present application, so that the implementation process of how to apply technical means to solve technical problems and achieve technical effects can be fully understood and implemented.

[0030] Embodiment 1

[0031] A back contact solar cell interconnection method, comprising the following steps:

[0032] (1) performing printing and sintering treatment on the back surface of the cell piece to form discontinuous positive fine grid lines and negative fine grid lines, and the positive fine grid lines and the negative fine grid lines are distributed in a staggered manner.

[0033] (2) printing a conical insulating adhesive on the negative fine grid line at the position corresponding to the discontinuous port of the positive solder strip, and printing a conductive adhesive on the positive fine grid line; printing a conical insulating adhesive on the positive fine grid line at the position corresponding to the discontinuous port of the negative solder strip, and printing a conductive adhesive on the negative fine grid line.

[0034] The conical insulating adhesive is silicone, the hardness is 5H, the length is 2mm, and the thickness is 30μm.

[0035] The conductive glue has a length of 1 mm and a width of 0.4 mm. The conductive glue adopts a silicone adhesive system, and a silver-plated circular plastic particle (5-10 μm in diameter) is used as a conductive carrier. The conductive carrier accounts for 60% of the total mass of the conductive glue.

[0036] (3) Isolation glue is printed at positions corresponding to the positive and negative welding ribbons at the edges of the battery piece; the isolation glue is silicone with a hardness of 3H, a length of 1 mm, a width of 1 mm, and a thickness of 10 μm.

[0037] (4) The positive and negative welding ribbons are alternately laid on the conductive glue, and are heated and cured at 130°C for 20 s to pre-fix the positive and negative welding ribbons on the battery piece.

[0038] The positive and negative welding ribbons both adopt a special-shaped welding ribbon; the special-shaped welding ribbon has a width of 0.6 mm and a thickness of 0.2 mm, and its cross section is trapezoidal, with a flat upper surface and a lower surface provided with a plurality of grooves at intervals. The grooves have a width of 10 μm and a depth of 5 μm.

[0039] (5) Then, a lamination welding process is performed to realize alloying connection of the positive welding ribbon and the fine grid line and the negative welding ribbon and the negative fine grid line.

[0040] Embodiment 2

[0041] A back contact solar cell interconnection method, comprising the following steps:

[0042] (1) A printing and sintering process is performed on the back surface of the battery piece to form discontinuous positive and negative fine grid lines, which are distributed in an alternating manner.

[0043] (2) At positions corresponding to the positive welding ribbons at the discontinuous openings, conical insulating glue is printed on the negative fine grid lines, and conductive glue is printed on the positive fine grid lines; at positions corresponding to the negative welding ribbons at the discontinuous openings, conical insulating glue is printed on the positive fine grid lines, and conductive glue is printed on the negative fine grid lines.

[0044] The conical insulating glue is epoxy glue with a hardness of 6H, a length of 2.5 mm, and a thickness of 35 μm.

[0045] The conductive glue has a length of 2 mm and a width of 0.6 mm. The conductive glue adopts an epoxy adhesive system, and a nickel-plated circular plastic particle (5-10 μm in diameter) is used as a conductive carrier. The conductive carrier accounts for 70% of the total mass of the conductive glue.

[0046] (3) Isolation glue is printed at positions corresponding to the positive and negative welding ribbons at the edges of the battery piece; the isolation glue is epoxy glue with a hardness of 4H, a length of 2 mm, a width of 1.5 mm, and a thickness of 20 μm.

[0047] (4) The positive electrode solder strip and the negative electrode solder strip are laid alternately on the conductive adhesive and heated and cured at 135°C for 15s to pre-fix the positive electrode solder strip and the negative electrode solder strip on the battery cell.

[0048] Both the positive and negative electrode solder strips mentioned above are irregularly shaped solder strips; the irregularly shaped solder strips are 0.7 mm wide and 0.2 mm thick, with a trapezoidal cross-section, a flat upper surface, and several grooves spaced apart on the lower surface. The grooves are 15 μm wide and 8 μm deep.

[0049] (5) Then, lamination welding is performed to achieve alloying connection between the positive electrode solder strip and the fine grid line, and between the negative electrode solder strip and the negative electrode fine grid line.

[0050] Example 3

[0051] A back-contact solar cell interconnection method includes the following steps:

[0052] (1) Printing and sintering process is performed on the back of the battery cell to form intermittent positive and negative fine grid lines, which are staggered.

[0053] (2) At the position of the interruption corresponding to the positive electrode solder strip, a conical insulating adhesive is printed on the negative electrode fine grid line, and a conductive adhesive is printed on the positive electrode fine grid line; at the position of the interruption corresponding to the negative electrode solder strip, a conical insulating adhesive is printed on the positive electrode fine grid line, and a conductive adhesive is printed on the negative electrode fine grid line.

[0054] The aforementioned conical insulating adhesive is made of silicone, with a hardness of 7H, a length of 3mm, and a thickness of 40μm.

[0055] The conductive adhesive described above has a length of 3 mm and a width of 0.8 mm. It uses an acrylic resin adhesive system and copper-plated spherical plastic particles (5-10 μm in diameter) as the conductive carrier. The conductive carrier accounts for 65% of the total mass of the conductive adhesive.

[0056] (3) Print the separator at the position corresponding to the positive electrode solder strip and the negative electrode solder strip on the edge of the battery cell; the separator is silicone with a hardness of 5H, a length of 3mm, a width of 2mm and a thickness of 30μm.

[0057] (4) The positive electrode solder strip and the negative electrode solder strip are laid alternately on the conductive adhesive and heated and cured at 140°C for 10 seconds to pre-fix the positive electrode solder strip and the negative electrode solder strip on the battery cell.

[0058] Both the positive and negative electrode solder strips mentioned above are irregularly shaped solder strips; the irregularly shaped solder strips are 0.8 mm wide and 0.25 mm thick, with a trapezoidal cross-section, a flat upper surface, and several grooves spaced apart on the lower surface. The grooves are 20 μm wide and 10 μm deep.

[0059] (5) Then, lamination welding is performed to achieve alloying connection between the positive electrode solder strip and the fine grid line, and between the negative electrode solder strip and the negative electrode fine grid line.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for interconnecting back-contact solar cells, characterized by comprising the following steps: (1) Printing and sintering process is performed on the back of the battery cell to form intermittent positive and negative fine grid lines, which are staggered. (2) At the position of the interruption corresponding to the positive electrode solder strip, a conical insulating adhesive is printed on the negative electrode fine grid line, and a conductive adhesive is printed on the positive electrode fine grid line; at the position of the interruption corresponding to the negative electrode solder strip, a conical insulating adhesive is printed on the positive electrode fine grid line, and a conductive adhesive is printed on the negative electrode fine grid line. (3) Print separator adhesive at the positions corresponding to the positive and negative electrode solder strips on the edge of the battery cell; (4) The positive electrode solder strip and the negative electrode solder strip are laid alternately on the conductive adhesive and heated to cure, so that the positive electrode solder strip and the negative electrode solder strip are pre-fixed on the battery cell; (5) Then, lamination welding is performed to achieve alloying connection between the positive electrode solder strip and the positive electrode fine grid line, and between the negative electrode solder strip and the negative electrode fine grid line; In step (4), both the positive electrode solder strip and the negative electrode solder strip are made of irregularly shaped solder strips. The width of the irregularly shaped solder strip is 0.6-0.8 mm, the thickness is 0.2-0.25 mm, the cross-section is trapezoidal, the upper surface is flat, and the lower surface is provided with several grooves at intervals, so that it can be bonded to the conductive adhesive at the connection of the fine grid line.

2. The back-contact solar cell interconnection method according to claim 1, characterized in that, In step (2), the conical insulating adhesive is silicone or epoxy adhesive with a hardness of 5-7H, a length of 2-3mm, and a thickness of 30-40μm.

3. The back-contact solar cell interconnection method according to claim 1, characterized in that, In step (2), the conductive adhesive uses a silicone, epoxy, or acrylic system, and uses round plastic particles with conductive metal deposited on their surface as conductive carriers.

4. The back-contact solar cell interconnection method according to claim 3, characterized in that, The diameter of the spherical plastic particles is 5-10 μm; the conductive metal is silver, nickel or copper.

5. The back-contact solar cell interconnection method according to claim 3, characterized in that, The conductive adhesive has a length of 1-3 mm and a width of 0.4-0.8 mm.

6. The back-contact solar cell interconnection method according to claim 1, characterized in that, In step (3), the isolation adhesive is silicone or epoxy adhesive with a hardness of 3-5H, a length of 1-3mm, a width of 1-2mm, and a thickness of 10-30μm.

7. The back-contact solar cell interconnection method according to claim 1, characterized in that, The groove has a width of 10-20 μm and a depth of 5-10 μm.

8. The back-contact solar cell interconnection method according to claim 1, characterized in that, In step (4), the heating and curing temperature is 130-140℃ and the time is 10-20s.

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