Laying method of back contact cell string

Abstract

The invention discloses a laying method of a back contact cell string, and belongs to the field of laying of cell strings of photovoltaic modules, and the method comprises a scheme I. The scheme I comprises the following steps: before thermal welding of back contact cells, the back surfaces of adjacent cells are pasted and interconnected through composite material small strips; the two sides of the composite material strip are coated with fluorine-containing film layers to resist ultraviolet attenuation, the fluorine-containing film layers on the bonding face of the composite material strip are covered with an EVA (polyethylene-polyvinyl acetate copolymer) adhesive film, and when the temperature of 125 DEG C is applied to the composite material strip, the EVA adhesive film is melted and crosslinked. According to the laying method of the back contact battery string, three technical schemes are provided, the first scheme can fix the sheet spacing and prevent welding warping and sheet spacing fluctuation caused during lamination, the second scheme can fix the sheet spacing and prevent sheet spacing fluctuation caused during lamination, and the third scheme can flatten warped batteries and the battery string. And the phenomenon of sheet combination in the laminating process can be effectively avoided, and the reject ratio is greatly reduced.

Description

Technical Field

[0001] The invention relates to the field of laying of cell strings of photovoltaic modules, and in particular to a method for laying a back-contact cell string. Background Art

[0002] BC cell is a back-contact cell, which is a solar cell technology. Its main feature is that the PN junction and metal contact are both located on the back of the solar cell, so that there is no electrode blocking the front of the cell, thereby increasing the area of ​​the cell absorbing sunlight, thereby improving the conversion efficiency and generating more electricity. The innovative design of the BC cell lies in its unobstructed structure on the front. This feature eliminates the light energy loss caused by traditional grid line obstruction, ensures the maximum utilization of incident photons, and makes the BC cell conversion efficiency higher. The structural advantages of BC cells are obvious and have multiple advantages. For example, benefiting from the front-side grid line-free structural design, the short-circuit current of the BC cell can be increased by about 7%. This significant gain is due to its unique back electrode layout.

[0003] At present, back-contact cells and modules have become an important development direction of the photovoltaic industry. However, due to single-sided welding and the different thermal expansion coefficients of the soldering ribbon and the silicon material, the cells and cell strings will produce obvious warping after the cells and the soldering ribbon alloy are welded, which will cause adverse effects in the laying, lamination and other processes. This is particularly serious in single-glass modules. After the current back-contact cells are strung together, conventional laying methods are still used, including cell string layout & convergence welding + film laying + backboard laying. Since all the strings are warped and the back of the single-glass module is a polymer backboard with a small weight, the warped cell strings cannot be flattened after laying. Therefore, it is easy to cause chipping during lamination, which in turn causes defects such as cracking, resulting in an increase in the defective rate. Summary of the invention

[0004] In order to solve the problem that the warped battery string cannot be flattened after laying, and the battery string is easily paralleled during lamination, which further causes defects such as chipping, the present invention provides a method for laying a back contact battery string, and the technical solution is as follows:

[0005] A method for laying a back-contact battery string includes a first solution, wherein the first solution includes the following steps:

[0006] S1: Before the back contact battery is thermally welded, the back sides of adjacent battery cells are first bonded and interconnected by small strips of composite material;

[0007] S2: A fluorine-containing film layer (polyvinylidene fluoride) is applied on both sides to resist UV attenuation, and a layer of EVA (polyethylene-polyvinyl acetate copolymer) film is covered outside the fluorine-containing film layer on the bonding surface. When a temperature of 125°C is applied to the composite material strip, the EVA film melts and cross-links;

[0008] S3: Use a tape sticking machine with a heating function to cut small strips of the composite material and stick them on the back surface of the battery, and heat and melt the small strips of EVA composite material to cross-link with the battery.

[0009] Preferably, the method for laying the back contact battery string also includes scheme 2, which includes the following steps:

[0010] S1: After the back contact cells are welded to form a battery string (there is a warping phenomenon), the battery string is laid out according to a certain circuit design;

[0011] S2: A small strip of composite material is pasted on the back of adjacent battery cells, and the small strip of composite material is located in a non-welding position.

[0012] Preferably, the method for laying the back contact battery string further includes scheme three, and the scheme three includes the following steps:

[0013] S1: After completing the battery string layout, adhesive film & backplane laying (called the laminated part), an additional layer of panel is added;

[0014] S2: Flatten the warped cells and cell strings in advance to prevent the lamination process from causing overlap. After the lamination is completed, remove the panel.

[0015] Preferably, the main body of the composite material strips in the scheme 1 and the scheme 2 is PET (polyethylene terephthalate) insulating material with a thickness of less than 300 microns.

[0016] Preferably, the coverage area of ​​the composite material strips in the scheme 1 is the edge position of adjacent batteries and the gap between the sheets, and does not occupy the welding position of the welding ribbon. For example, if n batteries are strung together, n-1 composite material strips are required, and then the welding ribbon is laid for hot welding to form a string.

[0017] Preferably, the composite material strips in step S2 of the second solution cover the edge positions of adjacent cells and the gaps between cells, but do not cover the interconnection strips between the cell sheets.

[0018] Preferably, the panel in step S1 of the third solution may be made of glass or metal material, and the panel serves to apply weight to the sample to be laminated.

[0019] Preferably, either the scheme 1 or the scheme 2 can be selected, the scheme 1 and the scheme 2 can be used in combination with the scheme 3, and the scheme 1, the scheme 2 and the scheme 3 can also be used independently of each other.

[0020] Solution 1 can fix the inter-cell spacing to prevent welding warping and inter-cell spacing fluctuations caused by lamination. Solution 2 can fix the inter-cell spacing to prevent inter-cell spacing fluctuations caused by lamination. Solution 3 can flatten the warped cells and battery strings, which can effectively avoid the phenomenon of cell paralleling during the lamination process and greatly reduce the defective rate.

[0021] Beneficial effects:

[0022] The beneficial effects produced by the technical solution of the present invention are as follows:

[0023] 1. The laying method of the back-contact battery string provides three technical solutions. Solution 1 can fix the sheet spacing to prevent welding warping and sheet spacing fluctuations caused by lamination. Solution 2 can fix the sheet spacing to prevent sheet spacing fluctuations caused by lamination. Solution 3 can flatten the warped batteries and battery strings, which can effectively avoid the phenomenon of parallel sheets during the lamination process and greatly reduce the defective rate.

[0024] 2. For the laying method of the back contact battery string, Scheme 1 and Scheme 2 can be used in a selective manner, and can also be used in combination with Scheme 3, or can be used independently, making the application scope wider and more practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 It is a structural schematic diagram of a first scheme of a method for laying a back-contact battery string of the present invention;

[0027] Figure 2 It is a structural schematic diagram of a second scheme of a method for laying a back-contact battery string of the present invention;

[0028] Figure 3 It is a structural schematic diagram of scheme 3 of a method for laying a back-contact battery string of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] like Figure 1 As shown, a method for laying a back contact battery string includes the following steps:

[0031] S1: Before the back contact battery is thermally welded, the backs of adjacent battery cells are first bonded and interconnected by a composite material strip. The main body of the composite material strip is PET (polyethylene terephthalate) insulating material with a thickness of less than 300 microns;

[0032] S2: A fluorine-containing film layer (polyvinylidene fluoride) is applied on both sides to resist UV attenuation, and a layer of EVA (polyethylene-polyvinyl acetate copolymer) film is covered outside the fluorine-containing film layer on the bonding surface. When a temperature of 125°C is applied to the composite material strip, the EVA film melts and cross-links;

[0033] S3: Use a tape sticking machine with a heating function to cut small strips of the composite material and stick them on the back surface of the battery, and heat and melt the small strips of EVA composite material to cross-link with the battery.

[0034] Specifically, the composite material strips cover the edge positions of adjacent batteries and the gaps between the sheets, and do not occupy the welding positions of the welding ribbons. For example, if n batteries are strung together, n-1 composite material strips are required, and then the welding ribbons are laid for thermal welding to form a string.

[0035] In this embodiment, the inter-sheet spacing can be fixed by this solution, thereby preventing welding warping and fluctuations in the inter-sheet spacing caused during lamination.

[0036] like Figure 2 As shown, the method for laying the back contact battery string also includes a second solution, and the second solution includes the following steps:

[0037] S1: After the back contact cells are welded to form a battery string (there is a warping phenomenon), the battery string is laid out according to a certain circuit design;

[0038] S2: A small strip of composite material is pasted on the back of adjacent battery cells. The main body of the small strip of composite material is PET (polyethylene terephthalate) insulating material with a thickness of less than 300 microns. The small strip of composite material is in a non-welding position. The small strip of composite material covers the edge of adjacent batteries and the gap between cells, but does not cover the interconnection strips between battery cells.

[0039] In this embodiment, the inter-sheet spacing can be fixed by this solution, thereby preventing the inter-sheet spacing from fluctuating during lamination.

[0040] like Figure 3 As shown, the method for laying the back contact battery string also includes a third solution, and the third solution includes the following steps:

[0041] S1: After the battery string layout, adhesive film & backplane laying are completed (called the laminated part), an additional layer of panel is added. The panel can be glass or metal material. The function of the panel is to apply weight on the laminated sample;

[0042] S2: Flatten the warped cells and cell strings in advance to prevent the lamination process from causing overlap. After the lamination is completed, remove the panel.

[0043] In this embodiment, the warped cells and cell strings can be flattened, and the phenomenon of paralleling cells during the lamination process can be effectively avoided.

[0044] Among the above solutions, you can choose either Solution 1 or Solution 2. Solution 1 and Solution 2 can be used in combination with Solution 3 at the same time. Solution 1, Solution 2 and Solution 3 can also be used independently of each other.

[0045] Embodiment 1:

[0046] Solution 1: Use alone:

[0047] S1: Before the back contact battery is thermally welded, the backs of adjacent battery cells are first bonded and interconnected by a composite material strip. The main body of the composite material strip is PET (polyethylene terephthalate) insulating material with a thickness of less than 300 microns;

[0048] S2: A fluorine-containing film layer (polyvinylidene fluoride) is applied on both sides to resist UV attenuation, and a layer of EVA (polyethylene-polyvinyl acetate copolymer) film is covered outside the fluorine-containing film layer on the bonding surface. When a temperature of 125°C is applied to the composite material strip, the EVA film melts and cross-links;

[0049] S3: Use a tape sticking machine with heating function to cut small strips of composite materials, stick them on the back surface of the battery, and heat and melt the EVA of the composite material strips to cross-link with the battery. The coverage area of ​​the composite material strips is the edge position of the adjacent battery and the gap between the sheets, and does not occupy the welding position of the welding ribbon. For example, if n batteries are strung together, n-1 composite material strips are required, and then the welding ribbon is laid for hot welding to form a string.

[0050] Embodiment 2:

[0051] Option 2 is used alone:

[0052] S1: After the back contact cells are welded to form a battery string (there is a warping phenomenon), the battery string is laid out according to a certain circuit design;

[0053] S2: A small strip of composite material is pasted on the back of adjacent battery cells. The main body of the small strip of composite material is PET (polyethylene terephthalate) insulating material with a thickness of less than 300 microns. The small strip of composite material is in a non-welding position. The small strip of composite material covers the edge of adjacent batteries and the gap between cells, but does not cover the interconnection strips between battery cells.

[0054] Embodiment three:

[0055] Solution 1 and Solution 3 are used together:

[0056] S1: Before the back contact battery is thermally welded, the backs of adjacent battery cells are first bonded and interconnected by a composite material strip. The main body of the composite material strip is PET (polyethylene terephthalate) insulating material with a thickness of less than 300 microns;

[0057] S2: A fluorine-containing film layer (polyvinylidene fluoride) is applied on both sides to resist UV attenuation, and a layer of EVA (polyethylene-polyvinyl acetate copolymer) film is covered outside the fluorine-containing film layer on the bonding surface. When a temperature of 125°C is applied to the composite material strip, the EVA film melts and cross-links;

[0058] S3: Use a tape sticking machine with heating function to cut the composite material strips, stick them on the back surface of the battery, and heat and melt the composite material strips EVA to cross-link with the battery. The composite material strips cover the edge positions of adjacent batteries and the gaps between the sheets, and do not occupy the welding position of the welding strip. For example, if n batteries are connected in a string, n-1 composite material strips are required, and then the welding strip is laid for thermal welding to form a string;

[0059] S4: After completing the battery string layout, adhesive film & back sheet laying (called the laminated part), an additional layer of panel is added;

[0060] S5: Flatten the warped cells and cell strings in advance to prevent the lamination process from causing overlap. After the lamination is completed, remove the panel.

[0061] Embodiment 4:

[0062] Solution 2 and Solution 3 are used together:

[0063] S1: After the back contact cells are welded to form a battery string (there is a warping phenomenon), the battery string is laid out according to a certain circuit design;

[0064] S2: A composite material strip is pasted on the back of adjacent battery cells. The main body of the composite material strip is PET (polyethylene terephthalate) insulating material with a thickness of less than 300 microns. The composite material strip is located in a non-welding position. The composite material strip covers the edge of the adjacent battery cells and the gap between the cells, but does not cover the interconnection strips between the battery cells.

[0065] S3: After completing the battery string layout, adhesive film & backplane laying (called the laminated part), an additional layer of panel is added;

[0066] S4: Flatten the warped cells and cell strings in advance to prevent the lamination process from causing overlap. After the lamination is completed, remove the panel.

[0067] The present invention provides three technical solutions. Solution 1 can fix the sheet spacing to prevent welding warping and sheet spacing fluctuations caused by lamination. Solution 2 can fix the sheet spacing to prevent sheet spacing fluctuations caused by lamination. Solution 3 can flatten the warped batteries and battery strings, and can effectively avoid the phenomenon of sheet paralleling during the lamination process, greatly reducing the defective rate. Solution 1 and Solution 2 can be used either separately, and can also be used in combination with Solution 3, or can be used independently, so that the scope of application is wider and the practicality is stronger.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for laying a back contact battery string, characterized in that: The method comprises the following steps: S1: Before the back contact battery is thermally welded, the back sides of adjacent battery cells are first bonded and interconnected by small strips of composite material; S2: A fluorine-containing film layer (polyvinylidene fluoride) is applied on both sides to resist UV attenuation, and a layer of EVA (polyethylene-polyvinyl acetate copolymer) film is covered outside the fluorine-containing film layer on the bonding surface. When a temperature of 125°C is applied to the composite material strip, the EVA film melts and cross-links; S3: Use a tape sticking machine with a heating function to cut small strips of the composite material and stick them on the back surface of the battery, and heat and melt the small strips of EVA composite material to cross-link with the battery.

2. A method for laying a back contact battery string according to claim 1, characterized in that: The method for laying the back contact battery string also includes a second solution, and the second solution includes the following steps: S1: After the back contact cells are welded to form a battery string (there is a warping phenomenon), the battery string is laid out according to a certain circuit design; S2: A small strip of composite material is pasted on the back of adjacent battery cells, and the small strip of composite material is located in a non-welding position.

3. A method for laying a back contact battery string according to claim 2, characterized in that: The method for laying the back contact battery string also includes a third solution, which includes the following steps: S1: After completing the battery string layout, adhesive film & backplane laying (called the laminated part), an additional layer of panel is added; S2: Flatten the warped cells and cell strings in advance to prevent the lamination process from causing overlap. After the lamination is completed, remove the panel.

4. A method for laying a back contact battery string according to claim 2, characterized in that: The main bodies of the composite material strips in the schemes 1 and 2 are both PET (polyethylene terephthalate) insulating materials with a thickness of less than 300 microns.

5. The method for laying a back contact battery string according to claim 1, characterized in that: In the first solution, the composite material strips cover the edge positions of adjacent batteries and the gaps between the sheets, and do not occupy the welding positions of the welding strips. For example, if n batteries are strung together, n-1 composite material strips are required, and then the welding strips are laid for thermal welding to form a string.

6. A method for laying a back contact battery string according to claim 2, characterized in that: The composite material strips in step S2 of the second solution cover the edge positions of adjacent cells and the gaps between cells, but do not cover the interconnection strips between the cells.

7. The method for laying a back contact battery string according to claim 3, characterized in that: The panel in step S1 of the third solution may be made of glass or metal material, and the panel is used to apply weight to the sample to be laminated.

8. The method for laying a back contact battery string according to claim 3, characterized in that: You can choose either solution 1 or solution 2. Solution 1 and solution 2 can be used in combination with solution 3. Solution 1, solution 2 and solution 3 can also be used independently of each other.

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