Series connection method of back contact solar cells

Abstract

The invention discloses a series connection method of back contact solar cells. The method comprises the following steps: printing a conductive adhesive at a position where a solar cell and a solder strip need to be conducted and contacted; the welding strip is pre-fixed on the surface of the battery piece through materials such as fixing glue or a glue film; and in the subsequent lamination link, the conductive adhesive is cured, and the welding strip is fixed on the surface of the battery piece to realize ohmic contact. The conductive adhesive is adopted to replace a traditional tin soldering technology, a bonding pad and solder paste are not needed, thick and thin grids do not need to be added, silver consumption can be remarkably reduced, and then the production cost is reduced; besides, a series connection method of low-temperature lamination and solidification is adopted, so that cell piece bending caused by high-temperature welding of the back contact solar cell is avoided, meanwhile, the risk of over-welding is reduced, and the product yield is effectively improved.

Description

Technical Field

[0001] The invention relates to the field of battery series connection, and in particular to a series connection method for back-contact solar cells. Background Art

[0002] The traditional method of connecting solar cells in series is mainly based on solder welding, which has the following problems: (1) In order to improve the welding effect, the traditional soldering process needs to print solder pads on the solar cells, and thicken the grid to ensure contact, which consumes a lot of silver and has high production costs; (2) Solder paste is needed in the welding process, and the solder paste will dissolve the silver grid line when heated, thus causing the risk of over-welding. At the same time, high-temperature welding can easily cause the solar cells to bend and damage the battery structure; (3) Since the insulating glue is applied to the adjacent positions of the solder joints, the insulating glue causes a certain height difference between the grid line and the solder strip. This height difference can easily cause cold soldering of adjacent solder joints, resulting in poor contact; (4) The solder joints formed after the soldering is cooled are relatively hard, which is not conducive to the dispersion of the battery stress and can easily cause hidden cracks in the battery. Therefore, a method for connecting back-contact solar cells in series that solves the above problems is needed. Summary of the invention

[0003] The object of the present invention is to provide a method for series connection of back-contact solar cells in view of the above problems.

[0004] To achieve the above object, the present invention provides the following technical methods:

[0005] The present invention comprises the following steps:

[0006] Print conductive glue at the locations where the solar cells and the solder strips need to be in contact;

[0007] The solder strip is pre-fixed on the surface of the cell by fixing glue or film material;

[0008] In the subsequent lamination process, the conductive adhesive is cured and the solder strip is fixed to the surface of the battery cell to achieve ohmic contact.

[0009] Furthermore, the conductive filler of the conductive adhesive is one or more of carbon, silver, nickel, tin, copper, silver-coated copper or tin-coated copper; the shape of the conductive filler is one or more of spherical, fibrous, flaky and dendritic.

[0010] Furthermore, the matrix of the conductive adhesive is one of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane, and acrylic resin.

[0011] Furthermore, the fixing glue is coated between two adjacent conductive glues; the ratio of the soldering tape width to the printing width of the fixing glue is 1:(0.1-3); the thickness of the fixing glue is set to 10 to 100 μm; the shape of the fixing glue is one of point, line, line segment, and curve.

[0012] Furthermore, the fixing glue is one of a photocuring glue or a pressure-sensitive adhesive; the battery cell printed with the photocuring glue needs to pass through a UV light box before lamination to cure the glue to fix the position of the solder strip; the battery cell printed with the pressure-sensitive adhesive needs to pass through a pressure device before lamination to slightly cure the glue to fix the position of the solder strip; the battery cell covered with the adhesive film material needs to be kept at 100±20℃ for a period of time before lamination to slightly melt the film to fix the position of the solder strip.

[0013] Furthermore, the adhesive film material is one of POE adhesive film, PVB adhesive film and EPE adhesive film; the adhesive film material needs to completely cover all welding strips.

[0014] Furthermore, the heating temperature of the lamination is 130° C.-160° C., so that the conductive adhesive can be completely cured to achieve adhesion and conduction between the gate line and the soldering tape.

[0015] Furthermore, the welding strip includes a positive electrode welding strip and a negative electrode welding strip, the positive electrode welding strip is connected to the positive electrode grid line through a conductive glue, and is isolated from the negative electrode grid line by an insulating glue; the negative electrode welding strip is connected to the negative electrode grid line through a conductive glue, and is isolated from the positive electrode grid line by an insulating glue; the positive electrode welding strip and the negative electrode welding strip are arranged alternately in sequence; the cross-sectional shape of the welding strip is one of a circle, a rectangle, and a triangle.

[0016] Compared with the prior art, the present invention provides a method for connecting back-contact solar cells in series, which has the following features:

[0017] Beneficial effects:

[0018] 1. Use conductive glue to replace traditional solder, no need for pads and fine grid thickening, effectively reduce silver consumption, and thus reduce production costs.

[0019] 2. Eliminate the risk of over-soldering and cell bending: Since solder paste is not used, the risk of over-soldering and cell bending caused by solder paste dissolving the silver grid line during high-temperature heating is eliminated.

[0020] 3. Eliminate the risk of cold soldering. Due to the presence of conductive glue, the height difference between the soldering strip and the soldering pad caused by the insulating glue is filled, solving the cold soldering problem commonly encountered in battery welding.

[0021] 4. The conductive adhesive realizes a micro-elastic connection between the battery cell and the soldering ribbon, so that the internal stress can be dispersed to each bonding position, reducing the risk of hidden cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a preparation method provided by an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the battery cell structure of an embodiment of the present invention;

[0024] Figure 3 It is a partial enlarged view of item A of the battery cell of an embodiment of the present invention;

[0025] Among them, 1-welding strip, 2-insulating glue, 3-fixing glue, 4-conductive glue, 5-grid line, 6-battery cell, 101-positive electrode welding strip, 102-negative electrode welding strip, 501-positive electrode grid line, 502-negative electrode grid line. DETAILED DESCRIPTION

[0026] The following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0027] like Figure 1-3 As shown, the present invention comprises the following steps:

[0028] Step S1: Printing conductive glue at the locations where the solar cells and the solder strips need to be in contact.

[0029] In this embodiment, the conductive adhesive 4 is arranged in such a manner that the conductive adhesive 4 and the insulating adhesive are evenly arranged above the gate line 5 and on both sides thereof near the gate line 5 , and the insulating adhesive 2 and the conductive adhesive 4 are alternately arranged in the first direction and the second direction.

[0030] In this embodiment, the matrix of the conductive adhesive 4 is one of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane, and acrylic resin; the conductive filler of the conductive adhesive is one or more of carbon, silver, nickel, tin, copper, silver-coated copper, or tin-coated copper; the shape of the conductive filler is one or more of spherical, fibrous, flaky, and dendritic.

[0031] Step S2: The soldering tape is pre-fixed on the surface of the battery cell by using materials such as fixing glue 3 or adhesive film.

[0032] In this embodiment, the welding strip 1 is divided into a positive electrode welding strip 101 and a negative electrode welding strip 102. The positive electrode welding strip 101 is connected to the positive electrode grid line 501 through the conductive glue 4, and is isolated from the negative electrode grid line 502 through the insulating glue 2; the negative electrode welding strip 102 is connected to the negative electrode grid line 502 through the conductive glue 4, and is isolated from the positive electrode grid line 501 through the insulating glue 2; the positive electrode welding strip 101 and the negative electrode welding strip 102 are arranged alternately in sequence; the cross-sectional shape of the welding strip 1 is circular, rectangular, or triangular.

[0033] In this embodiment, the fixing glue 3 is one of a light-curing glue or a pressure-sensitive glue; the position of applying the glue is: between two adjacent conductive glues 4 in the second direction; the printing width of the fixing glue 3 is: 0.5 times the width of the solder strip ≤ printing width ≤ 1.5 times the width of the solder strip; the thickness of the fixing glue 3 is set to: 10 to 100 μm; the shape of the fixing glue 3 is one of a dot shape, a line shape, a line segment shape, and a curve shape;

[0034] In this embodiment, the cell printed with the photocurable adhesive needs to pass through a UV light box before lamination to lightly cure the fixing adhesive to fix the position of the solder strip;

[0035] In another embodiment of the present invention, the battery cell printed with the pressure-sensitive adhesive needs to be passed through a pressure device before lamination to allow the glue to be slightly cured to fix the position of the soldering tape.

[0036] In another embodiment of the present invention, the adhesive film is one of POE adhesive film, PVB adhesive film and EPE adhesive film; the adhesive film needs to completely cover all welding strips; the battery cell covered with the adhesive film needs to be kept at 100±20℃ for a period of time before lamination to allow the film to melt slightly to fix the position of the welding strips.

[0037] Step S3: In the subsequent lamination process, the conductive adhesive 4 is cured and the soldering tape 1 is fixed to the surface of the battery cell 6 to achieve ohmic contact.

[0038] In this embodiment, the lamination heating temperature is 130° C.-160° C., so that the conductive adhesive 4 can be completely cured, and the grid line 5 and the soldering ribbon 1 are bonded and connected to obtain a back contact battery assembly.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for connecting back-contact solar cells in series, characterized in that: The following steps are involved: Print conductive glue at the locations where the solar cells and the solder strips need to be in contact; The solder strip is pre-fixed on the surface of the cell by fixing glue or film material; In the subsequent lamination process, the conductive adhesive is cured and the solder strip is fixed to the surface of the battery cell to achieve ohmic contact.

2. The method for connecting back-contact solar cells in series according to claim 1, characterized in that: The conductive filler of the conductive adhesive is one or more of carbon, silver, nickel, tin, copper, silver-coated copper or tin-coated copper; the shape of the conductive filler is one or more of spherical, fibrous, flaky and dendritic.

3. The method for connecting back-contact solar cells in series according to claim 1, characterized in that: The matrix of the conductive adhesive is one of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane and acrylic resin.

4. A back-contact solar cell series connection method according to claim 1, characterized in that: The fixing glue is coated between two adjacent conductive adhesives; the ratio of the width of the soldering tape to the printing width of the fixing glue is 1:(0.1-3); the thickness of the fixing glue is set to 10-100 μm; the shape of the fixing glue is one of point, line, line segment, and curve.

5. A method for connecting back-contact solar cells in series according to claim 4, characterized in that: The fixing glue is one of a photocuring glue or a pressure-sensitive adhesive; the battery cell printed with the photocuring glue needs to pass through a UV light box before lamination to cure the glue to fix the position of the soldering tape; the battery cell printed with the pressure-sensitive adhesive needs to pass through a pressure device before lamination to slightly cure the glue to fix the position of the soldering tape; the battery cell covered with the adhesive film material needs to be kept at 100±20℃ for a period of time before lamination to slightly melt the film to fix the position of the soldering tape.

6. The method for connecting back-contact solar cells in series according to claim 1, characterized in that: The adhesive film material is one of POE adhesive film, PVB adhesive film and EPE adhesive film; the adhesive film material needs to completely cover all welding strips.

7. The method for connecting back-contact solar cells in series according to claim 1, characterized in that: The heating temperature of the lamination is 130° C.-160° C., so that the conductive adhesive can be completely cured to achieve adhesion and conduction between the gate line and the welding strip.

8. The method for connecting back-contact solar cells in series according to claim 1, characterized in that: The welding strips include positive welding strips and negative welding strips. The positive welding strips are connected to the positive grid lines through conductive glue and isolated from the negative grid lines through insulating glue. The negative welding strips are connected to the negative grid lines through conductive glue and isolated from the positive grid lines through insulating glue. The positive welding strips and the negative welding strips are alternately arranged in sequence. The cross-sectional shape of the welding strips is one of circular, rectangular and triangular.

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