Back contact solar cell interconnection method

Abstract

The invention relates to the technical field of solar cells, in particular to a back contact solar cell interconnection method, which comprises the following steps of: arranging positive fine grid lines and negative fine grid lines on the back surfaces of cells in a staggered manner; printing conical insulating glue on the negative electrode fine grid lines and printing conductive glue on the positive electrode fine grid lines at the positions, corresponding to the positive electrode welding strips, of the discontinuous openings; printing a conical insulating adhesive on the positive electrode fine grid line and printing a conductive adhesive on the negative electrode fine grid line at the position of the discontinuous opening corresponding to the negative electrode welding strip; printing isolation glue on the edge of the cell corresponding to the positive electrode solder strip and the negative electrode solder strip; laying a positive electrode welding strip and a negative electrode welding strip on the conductive adhesive in a staggered manner; and then carrying out lamination welding treatment. Connection is achieved by printing the conductive adhesive between the fine grid lines, traditional main grid line connection is removed, and the use amount of silver paste is reduced; and a welding strip in a specific shape can be directly laid on the conductive adhesive for pre-curing, so that the welding strip is ensured to be fully connected with the fine grid through the conductive adhesive, and the problem of insufficient welding in later lamination is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, in particular to a back contact solar cell interconnection method. Background Art

[0002] Against the backdrop of global warming and the increasing shortage of non-renewable energy such as oil and natural gas, the development of new energy is imminent. Solar energy, as an inexhaustible clean energy source, is the first to bear the brunt. Improving the efficiency of photoelectric conversion is the focus of solar technology. Back-contact solar technology is to print the front grid lines and electrodes of the battery to the back through special technical means, forming a cross arrangement of positive and negative electrodes on the back of the battery. This technology can effectively improve the efficiency of solar cells and make solar cells more beautiful. It is also compatible with multiple technologies such as PERC, TOPCON, and HJT cells.

[0003] The back contact solar cell in the prior art, such as the attached Figure 1-2 As shown, the positive and negative fine grids on the back of the battery are arranged horizontally and crosswise, the positive and negative main grids are arranged vertically and crosswise, the negative fine grids on both sides of the positive main grid are printed with rectangular insulating glue, and the positive fine grids on both sides of the negative main grid are printed with rectangular insulating glue; after printing solder paste above the PAD points of the positive and negative main grids, a flat solder strip is laid and hot welded, or curing glue is printed at the PAD point to fix the solder strip, and then lamination welding is performed. However, the above process has problems such as large consumption of silver paste, gaps between the solder strip and the grid line resulting in insulation cold solder joints, and direct pressure impact of the solder strip on the battery cell causing it to rupture. Based on this, a back contact solar cell interconnection method is proposed. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a back-contact solar cell interconnection method, which removes the main grid to reduce the use of silver paste and ensures that the special-shaped welding strip is fully connected with the fine grid through the conductive adhesive, effectively solving the problem of cold soldering in the later lamination.

[0005] To achieve the above object, the present invention provides the following technical solution: a back contact solar cell interconnection method, comprising the following steps:

[0006] (1) Printing and sintering the back of the battery cell to form intermittent positive electrode fine grid lines and negative electrode fine grid lines, and the positive electrode fine grid lines and the negative electrode fine grid lines are staggered;

[0007] (2) The discontinuity corresponds to the position of the positive electrode welding strip, and a conical insulating glue is printed on the negative electrode fine grid line, and a conductive glue is printed on the positive electrode fine grid line; The discontinuity corresponds to the position of the negative electrode welding strip, and a conical insulating glue is printed on the positive electrode fine grid line, and a conductive glue is printed on the negative electrode fine grid line;

[0008] (3) Printing isolation glue at the position of the positive electrode welding strip and the negative electrode welding strip at the edge of the battery cell;

[0009] (4) alternately laying positive electrode welding strips and negative electrode welding strips on the conductive adhesive, heating and curing, so that the positive electrode welding strips and negative electrode welding strips are pre-fixed on the battery cell;

[0010] (5) Subsequently, a lamination welding process is performed to achieve alloy connection between the positive electrode welding strip and the fine grid wire, and between the negative electrode welding strip and the negative electrode fine grid wire.

[0011] Preferably, in step (2), the conical insulating glue is silicone or epoxy glue, with a hardness of 5-7H, a length of 2-3mm, and a thickness of 30-40μm.

[0012] Preferably, in step (2), the conductive adhesive is made of a silicone, epoxy or acrylic system, and round plastic particles with a conductive metal plated on the surface are used as the conductive carrier.

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

[0014] Preferably, the conductive adhesive has a length of 1-3 mm and a width of 0.4-0.8 mm.

[0015] Preferably, 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.

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

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

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

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

[0020] The present invention realizes connection by printing conductive glue between fine grid lines, thereby eliminating the traditional main grid line connection and greatly reducing the amount of silver paste used; and a soldering strip of a specific shape can be directly laid on the conductive glue for pre-curing, ensuring that the soldering strip is fully connected to the fine grid through the conductive glue, effectively solving the problem of cold soldering in the later lamination stage.

[0021] The present invention prints an isolation adhesive on the edge of the battery cell, which can mitigate the direct pressure impact between the welding strip and the battery cell during the lamination welding process, play a buffering role, and reduce the risk of battery cell rupture.

[0022] The present invention uses a special-shaped welding ribbon, and the flow of the adhesive film acts on the trapezoidal cross-section during lamination, which can reduce the shear force in the horizontal direction and reduce the risk of welding ribbon deviation; at the same time, a groove is provided on the bottom surface of the special-shaped welding ribbon to combine with the conductive adhesive at the connection of the fine grid, thereby ensuring a close connection between the welding ribbon and the conductive adhesive and avoiding the situation in which the adhesive film flows into the gap between the welding ribbon and the conductive adhesive during lamination and causes insulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

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

[0025] Figure 2 for Figure 1 The enlarged schematic diagram of part A in the middle;

[0026] Figure 3 This is a schematic diagram of the back contact battery interconnection in the present invention;

[0027] Figure 4 for Figure 3 The enlarged schematic diagram of part B in the middle;

[0028] Figure 5 Schematic diagram of the front and side surfaces of the special-shaped welding strip in the present invention. DETAILED DESCRIPTION

[0029] The following examples are used to explain the implementation methods of the present application in detail, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0030] Example 1

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

[0032] (1) Printing and sintering treatment is performed on the back of the battery cell to form intermittent positive electrode fine grid lines and negative electrode fine grid lines, and the positive electrode fine grid lines and the negative electrode fine grid lines are staggered.

[0033] (2) The discontinuity corresponds to the position of the positive electrode welding strip, and a conical insulating glue is printed on the negative electrode fine grid line, and a conductive glue is printed on the positive electrode fine grid line; The discontinuity corresponds to the position of the negative electrode welding strip, and a conical insulating glue is printed on the positive electrode fine grid line, and a conductive glue is printed on the negative electrode fine grid line;

[0034] The above-mentioned cone-shaped insulating glue is silica gel, with a hardness of 5H, a length of 2mm and a thickness of 30μm.

[0035] The conductive adhesive has a length of 1 mm and a width of 0.4 mm. The conductive adhesive adopts a silicone adhesive system and uses silver-plated round plastic particles (with a diameter of 5-10 μm) as a conductive carrier. The conductive carrier accounts for 60% of the total mass of the conductive adhesive.

[0036] (3) Printing isolation glue at the position of the positive electrode welding strip and the negative electrode welding strip at the edge of the battery cell; the isolation glue is silicone with a hardness of 3H, a length of 1mm, a width of 1mm, and a thickness of 10μm.

[0037] (4) Alternately lay positive electrode welding strips and negative electrode welding strips on the conductive adhesive, heat and cure at 130° C. for 20 seconds, so that the positive electrode welding strips and negative electrode welding strips are pre-fixed on the battery cell;

[0038] The positive electrode welding strip and the negative electrode welding strip are both shaped welding strips; the shaped welding strip has a width of 0.6 mm, a thickness of 0.2 mm, a trapezoidal cross section, a flat upper surface, and a plurality of grooves arranged at intervals on the lower surface. The width of the grooves is 10 μm, and the depth is 5 μm.

[0039] (5) Subsequently, a lamination welding process is performed to achieve alloy connection between the positive electrode welding strip and the fine grid wire, and between the negative electrode welding strip and the negative electrode fine grid wire.

[0040] Example 2

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

[0042] (1) Printing and sintering treatment is performed on the back of the battery cell to form intermittent positive electrode fine grid lines and negative electrode fine grid lines, and the positive electrode fine grid lines and the negative electrode fine grid lines are staggered.

[0043] (2) The discontinuity corresponds to the position of the positive electrode welding strip, and a conical insulating glue is printed on the negative electrode fine grid line, and a conductive glue is printed on the positive electrode fine grid line; The discontinuity corresponds to the position of the negative electrode welding strip, and a conical insulating glue is printed on the positive electrode fine grid line, and a conductive glue is printed on the negative electrode fine grid line;

[0044] The above-mentioned cone-shaped insulating glue is epoxy glue, with a hardness of 6H, a length of 2.5mm and a thickness of 35μm.

[0045] The conductive adhesive has a length of 2 mm and a width of 0.6 mm. The conductive adhesive adopts an epoxy resin adhesive system and uses round plastic particles (with a diameter of 5-10 μm) with nickel plating on the surface as a conductive carrier. The conductive carrier accounts for 70% of the total mass of the conductive adhesive.

[0046] (3) Printing isolation glue at the position corresponding to the positive electrode welding strip and the negative electrode welding strip at the edge of the battery cell; the isolation glue is epoxy glue with a hardness of 4H, a length of 2mm, a width of 1.5mm, and a thickness of 20μm.

[0047] (4) alternately laying positive electrode welding strips and negative electrode welding strips on the conductive adhesive, heating and curing at 135° C. for 15 seconds, so that the positive electrode welding strips and negative electrode welding strips are pre-fixed on the battery cell;

[0048] The positive electrode welding strip and the negative electrode welding strip are both shaped welding strips; the shaped welding strip has a width of 0.7 mm, a thickness of 0.2 mm, a trapezoidal cross section, a flat upper surface, and a plurality of grooves arranged at intervals on the lower surface. The width of the grooves is 15 μm, and the depth is 8 μm.

[0049] (5) Subsequently, a lamination welding process is performed to achieve alloy connection between the positive electrode welding strip and the fine grid wire, and between the negative electrode welding strip and the negative electrode fine grid wire.

[0050] Example 3

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

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

[0053] (2) The discontinuity corresponds to the position of the positive electrode welding strip, and a conical insulating glue is printed on the negative electrode fine grid line, and a conductive glue is printed on the positive electrode fine grid line; The discontinuity corresponds to the position of the negative electrode welding strip, and a conical insulating glue is printed on the positive electrode fine grid line, and a conductive glue is printed on the negative electrode fine grid line;

[0054] The above-mentioned cone-shaped insulating glue is silica gel, with a hardness of 7H, a length of 3mm and a thickness of 40μm.

[0055] The conductive adhesive has a length of 3 mm and a width of 0.8 mm. The conductive adhesive adopts an acrylic resin adhesive system and uses round plastic particles (with a diameter of 5-10 μm) with copper-plated surfaces as conductive carriers. The conductive carriers account for 65% of the total mass of the conductive adhesive.

[0056] (3) Printing isolation glue at the position of the positive electrode welding strip and the negative electrode welding strip at the edge of the battery cell; the isolation glue is silicone with a hardness of 5H, a length of 3mm, a width of 2mm, and a thickness of 30μm.

[0057] (4) Alternately lay positive electrode welding strips and negative electrode welding strips on the conductive adhesive, heat and cure at 140° C. for 10 seconds, so that the positive electrode welding strips and negative electrode welding strips are pre-fixed on the battery cell;

[0058] The positive electrode welding strip and the negative electrode welding strip are both shaped welding strips; the shaped welding strip has a width of 0.8 mm and a thickness of 0.25 mm, and a trapezoidal cross section, with a flat upper surface and a plurality of grooves arranged at intervals on the lower surface. The width of the grooves is 20 μm and the depth is 10 μm.

[0059] (5) Subsequently, a lamination welding process is performed to achieve alloy connection between the positive electrode welding strip and the fine grid wire, and between the negative electrode welding strip and the negative electrode fine grid wire.

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

Claims

1. A back contact solar cell interconnection method, characterized in that it comprises the following steps: (1) Printing and sintering the back of the battery cell to form intermittent positive electrode fine grid lines and negative electrode fine grid lines, and the positive electrode fine grid lines and the negative electrode fine grid lines are staggered; (2) The discontinuity corresponds to the position of the positive electrode welding strip, and a conical insulating glue is printed on the negative electrode fine grid line, and a conductive glue is printed on the positive electrode fine grid line; The discontinuity corresponds to the position of the negative electrode welding strip, and a conical insulating glue is printed on the positive electrode fine grid line, and a conductive glue is printed on the negative electrode fine grid line; (3) Printing isolation glue at the position of the positive electrode welding strip and the negative electrode welding strip at the edge of the battery cell; (4) alternately laying positive electrode welding strips and negative electrode welding strips on the conductive adhesive, heating and curing, so that the positive electrode welding strips and negative electrode welding strips are pre-fixed on the battery cell; (5) Subsequently, a lamination welding process is performed to achieve alloy connection between the positive electrode welding strip and the fine grid wire, and between the negative electrode welding strip and the negative electrode fine grid wire.

2. The back contact solar cell interconnection method according to claim 1, characterized in that: In step (2), the conical insulating glue is silicone or epoxy glue, 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 is made of a silicone, epoxy or acrylic system, and round plastic particles with a conductive metal plated on the surface are used as the conductive carrier.

4. The back contact solar cell interconnection method according to claim 3, characterized in that: The diameter of the round 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 glue is silicone or epoxy glue, 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: In step (4), both the positive electrode welding strip and the negative electrode welding strip are shaped welding strips; the width of the shaped welding strip is 0.6-0.8mm, the thickness is 0.2-0.25mm, the cross-section is trapezoidal, the upper surface is flat, and the lower surface is provided with a plurality of grooves at intervals.

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

9. The back contact solar cell interconnection method according to claim 1, characterized in that: In step (4), the temperature of the heating and curing is 130-140° C. and the time is 10-20 seconds.

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