Solar cell busbar-free integrated film and preparation method therefor

Abstract

Disclosed in the present invention is a solar cell busbar-free integrated film. The integrated film comprises a conventional encapsulant film and a pretreated encapsulant film, wherein the grammage ratio of the pretreated encapsulant film to the conventional encapsulant film is (1-3):(3-1). In the present invention, a pretreated encapsulant film has a pre-crosslinking degree of 20%-40%, and uses the electron irradiation energy of 10-20 kGy, such that an encapsulant film with suitable fluidity can be obtained, without affecting the contact between a solder ribbon and a finger and causing cosmetic defects in modules. Moreover, the grammage percentage of the pretreated encapsulant film in the busbar-free integrated film is 40% to 70%, an electroluminescence image of a formed battery module is normal, and the battery module has no cosmetic defect. By means of an out-of-mold lamination technique combined with processes, such as dispensing and soldering dispensing, a skin film and a conventional photovoltaic encapsulant film are replaced, thereby implementing a solar cell busbar-free technique.

Description

A solar cell busbar-free integrated film and its preparation method Technical Field

[0001] The present invention relates to a solar cell busbar-free integrated film and a preparation method thereof, and relates to H01L, and in particular to the field of battery components for converting light energy into electrical energy. Background Art

[0002] Cost reduction and efficiency improvement is one of the main themes of the photovoltaic industry. The fine grid lines of traditional crystalline silicon solar cells are connected by main grid lines, and the solar cells are connected to each other by welding ribbons on the main grid to form a battery string. The main grid-free technology directly uses welding ribbons to connect the fine grids, thereby eliminating the main grid and achieving the purpose of cost reduction. The existing main grid-free solar cells have three processing technologies: dispensing, welding dispensing, and Smartwire. The Smartwire process is complex and costly. The dispensing and welding dispensing processes each have their own advantages and disadvantages. This application has developed an integrated adhesive film that can replace the existing skin film and conventional film with the dispensing or welding dispensing process, optimize the processing technology of main grid-free solar cells, reduce the precision technical indicators of the adhesive film, make the process simpler, and increase the processing speed.

[0003] Chinese invention patent CN202211492760.X discloses a segmented low-temperature solder ribbon, a main grid-free IBC battery string, a battery assembly and its packaging method, which integrates the segmented low-temperature solder ribbon with the insulating area, thereby removing the printing of the insulating area on the main grid-free IBC battery cell, so that it can effectively prevent the short circuit problem caused by the solder ribbon offset from the insulating area during the lamination process. However, there is no obvious improvement in the simplification of the process. Chinese invention patent CN202110133529.0 discloses a composite film for interconnecting a main grid-free heterojunction solar cell assembly and its preparation method. By using a hollow composite film, the transmittance after lamination can reach more than 90%, which improves the photoelectric conversion power of the battery assembly. However, the composite film will affect the contact between the solder ribbon and the fine grid during the lamination process, resulting in poor electroluminescent image.

[0004] Summary of the Invention

[0005] In order to optimize the fluidity of the main grid-free integrated film, make the EL electroluminescent image of the cell excellent, and make the appearance of the component free of defects such as bubbles and lines, the first aspect of the present invention provides a solar cell main grid-free integrated film, the integrated film includes a conventional adhesive film and a pre-treated adhesive film, and the gram weight ratio of the pre-treated adhesive film to the conventional adhesive film is (1-3): (3-1).

[0006] As a preferred embodiment, the raw materials for preparing the pre-treated adhesive film include, by weight: 100 parts of base resin, 0.5-2 parts of cross-linking agent, and 0.1-2 parts of auxiliary cross-linking agent.

[0007] As a preferred embodiment, the matrix resin is selected from one or a combination of EVA (ethylene-vinyl acetate copolymer) matrix resin, POE (polyethylene octene co-elastomer) matrix resin, and PVB (polyvinyl butyral) matrix resin.

[0008] As a preferred embodiment, the specific gravity of the EVA matrix resin is 0.8-1.0 g / cm 3 The melt index at 190°C and 2.16kg is 12-26g / 10min; the specific gravity of the POE matrix resin is 0.8-1.0g / cm 3 , the melt index at 190℃ and 2.16kg is 3-22g / 10min.

[0009] As a preferred embodiment, the specific gravity of the EVA matrix resin is 0.952 g / cm 3 The melt index at 190°C and 2.16 kg is 25 g / 10 min; the specific gravity of the POE matrix resin is 0.8-0.9 g / cm 3 , the melt index at 190℃ and 2.16kg is 4-14g / 10min.

[0010] As a preferred embodiment, the cross-linking agent is a peroxide cross-linking agent, and the peroxide cross-linking agent is a tert-butyl peroxide cross-linking agent.

[0011] As a preferred embodiment, the tert-butyl peroxide cross-linking agent includes but is not limited to one or a combination of tert-butyl peroxycarbonate-2-ethylhexyl ester and tert-amyl peroxycarbonate-2-ethylhexyl ester.

[0012] As a preferred embodiment, the auxiliary cross-linking agent includes but is not limited to triallyl isocyanurate, 2,4,6-triallyloxy-1,3,5-triazine, trimethylolpropane triacrylate, or a combination of several thereof.

[0013] As a preferred embodiment, the pre-crosslinking degree of the pre-treated adhesive film is 10%-50%, and the crosslinking energy used for the pre-treatment of the pre-treated adhesive film is 10-80 kGy.

[0014] As a preferred embodiment, the pre-crosslinking degree of the pre-treated adhesive film is 20%-40%, and the cross-linking energy used for the pre-treatment of the pre-treated adhesive film is 10-20 kGy.

[0015] During the experiment, the applicant found that the prepared solar cell adhesive film, combined with the dispensing or welding dispensing process, is applied to the busbar-free process of solar cells, which can optimize the processing technology of busbar-free solar cells and reduce the problem of virtual connection between the welding ribbon and the fine grid. The welding ribbon is connected to the cell by dispensing or welding dispensing, and there is a gap between the cell. When the fluidity of the adhesive film is too high, after lamination, the adhesive film will enter the gap between the welding ribbon and the cell, affecting the contact between the welding ribbon and the fine grid, and producing black lines in the electroluminescence test; when the fluidity of the adhesive film is too low, after lamination, it is easy to produce poor appearance of the component, bubbles, and lines. By controlling the electron irradiation energy of the pre-treated adhesive film, the pre-crosslinking degree of the pre-treated adhesive film can be controlled, so that the adhesive film has lower fluidity. The integrated film obtained by compounding the pre-treated adhesive film with the conventional adhesive film can have appropriate fluidity, which will neither affect the EL performance of the solar cell nor cause poor appearance such as bubbles and lines.

[0016] As a preferred embodiment, the pretreatment method of the pretreated adhesive film is selected from one or a combination of corona, electron irradiation, and ultraviolet irradiation.

[0017] As a preferred embodiment, the pre-treated adhesive film accounts for 25-75% of the total weight of the busbar-free integrated film.

[0018] As a preferred embodiment, the weight of the pre-treated adhesive film in the busbar-free integrated film accounts for 40-70%.

[0019] As a preferred embodiment, when the pre-crosslinking degree of the pre-treated film is 20-30%, the gram weight of the pre-treated film in the integrated film without main grid is 50-70%; when the pre-crosslinking degree of the pre-treated film is 30-40%, the gram weight of the pre-treated film in the integrated film without main grid is 40-50%.

[0020] During the experiment, the applicant found that when the pre-crosslinking degree is 20-40% and the weight ratio of the pre-treated film in the integrated film is 40-70%, the electroluminescent image of the cell formed is normal and the appearance of the cell has no defects.

[0021] A second aspect of the present invention provides a method for preparing a busbar-free integrated film for a solar cell, comprising the following steps:

[0022] S1 uses out-of-mold lamination technology to laminate pre-treated film and conventional film;

[0023] S2 laminates the pretreated adhesive film surface onto the cell sheet and laminates the conventional adhesive film surface onto the solar back panel or glass to obtain a cell module.

[0024] As a preferred embodiment, the technical parameters of the out-of-mold composite technology are as follows: mold temperature 80-100°C; rubber roller temperature 0-50°C; steel roller temperature 0-50°C; and pulling speed 5-20m / min.

[0025] As a preferred embodiment, in step 1, the pretreated film is loaded by contacting with a rubber roller, and the conventional film is loaded by contacting with a steel roller after being extruded from a die.

[0026] During the experiment, the applicant found that by controlling the processing parameters between the pretreated film and the conventional film, the overall composite performance of the integrated film can be optimized and the delamination of the integrated film can be avoided. The possible reason is speculated to be: the pretreated film adopts an optimized pre-crosslinking degree, which can maintain good bonding performance between the pretreated film and the conventional film. At the preferred temperature and pulling speed, the pretreated film and the conventional film have a certain flexibility, can fit tightly, have good bonding effect, and are not easy to delaminate.

[0027] As a preferred embodiment, the solar cell busbar-free integrated film is applied to battery components containing welding strips and grid lines, including but not limited to heterojunction, TOPCon, Perc, etc.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The solar cell of the present invention has no main grid integrated film, and the pre-treated adhesive film adopts a pre-crosslinking degree of 20%-40%, and the electron irradiation energy used is 10-20kGy, which can obtain an adhesive film with suitable fluidity, will not affect the contact between the welding strip and the fine grid, and will not cause poor appearance of the component.

[0030] (2) The solar cell of the present invention has no main grid integrated film, and the pre-treated adhesive film adopts a pre-crosslinking degree of 20%-40%, and the gram weight of the pre-treated adhesive film in the main grid integrated film accounts for 40-70%. The electroluminescent image of the formed cell is normal, and the appearance of the battery component has no defects.

[0031] (3) The solar cell of the present invention has no main grid integrated film and adopts an out-of-mold composite process with a mold temperature of 80-100°C, a rubber roller temperature of 0-50°C, a steel roller temperature of 0-50°C, and a traction speed of 5-20m / min. The thickness of the integrated adhesive film formed is uniform, and the composite bonding between the pretreated adhesive film and the conventional adhesive film is good and not easy to delaminate.

[0032] (4) The solar cell of the present invention has no main grid integrated film and can be applied to solar cell modules with adhesive films made of various resin materials, and has a wide range of applications.

[0033] (5) The solar cell busbar-free integrated film of the present invention replaces the skin film and conventional photovoltaic film through out-of-mold composite technology, combined with dispensing or welding dispensing processes, to achieve busbar-free technology for solar cells and achieve good EL and appearance performance of solar cell modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is an EL image of a solar cell prepared with a busbar-free integrated film and tested as Grade A in the embodiment;

[0035] FIG2 is an EL image of a solar cell prepared with a busbar-free integrated film and tested as Grade B in the embodiment;

[0036] FIG3 is a partial view of appearance defects at different positions of a solar cell module made of a solar cell without a busbar integrated film and tested as Grade C in the embodiment.

[0037] Figure 4 is a schematic diagram of an out-of-mold composite device;

[0038] In the figure: 1. Mold; 2. Steel rod; 3. Rubber roller; 4. Conventional rubber film; 5. Pre-treated rubber film. DETAILED DESCRIPTION

[0039] Example

[0040] A solar cell busbar-free integrated film comprises 4 conventional adhesive films and 5 pre-treated adhesive films. The raw materials for preparing the 5 pre-treated adhesive films include, by weight, 100 parts of base resin, 1.3 parts of cross-linking agent, and 1 part of auxiliary cross-linking agent.

[0041] The matrix resin is EVA resin with a specific gravity of 0.952 g / cm 3 The melt index at 190°C and 2.16kg is 25g / 10min. It is purchased from Sailbon, model V2825.

[0042] The cross-linking agent is tert-butyl peroxycarbonate-2-ethylhexyl ester, and the auxiliary cross-linking agent is trimethylolpropane triacrylate.

[0043] The cross-linking energy used in the 5 pre-treatment of the pre-treated film is 15±5 kGy.

[0044] The pretreatment method of the pretreated film 5 is electron irradiation.

[0045] The conventional films are EVA films. The raw materials used to prepare the conventional films are the same as those used for the pretreated films. The conventional films are placed in an extruder at 80° C. for 2 minutes and then extruded from a die head.

[0046] A diagram of the out-of-mold composite equipment is shown in Figure 4. A method for preparing a solar cell busbar-free integrated film comprises the following steps:

[0047] S1 adopts out-of-mold lamination technology, 5 pre-treated films are loaded in contact with 3 rubber rollers, 4 conventional films are extruded from the die and loaded in contact with 2 steel rollers, and the 5 pre-treated films and 4 conventional films are laminated by co-extrusion;

[0048] S2 is to laminate the 5 pre-treated film surfaces onto the solar cell and the 4 conventional film surfaces onto the solar back panel or glass to obtain a solar cell assembly.

[0049] The technical parameters of the out-of-mold composite technology are as follows: 1. Mold temperature 90° C.; 3. Rubber roller temperature 45° C.; 2. Steel roller temperature 45° C.; and pulling speed 10 m / min.

[0050] The pre-crosslinking degree and gram-to-weight ratio of the pretreated film are shown in Table 1-3.

[0051] Table 1

[0052] Table 2

[0053] Table 3

[0054] After testing, the performance test of the battery assemblies prepared in Examples 1-23 was B grade; the performance test of the battery assemblies prepared in Examples 24-30 was A grade; and the performance test of the battery assemblies prepared in Examples 31-45 was C grade.

[0055] Performance Testing

[0056] 1. EL image test: The EL images of the battery components prepared in Examples 1-45 were tested.

[0057] 2. Appearance of battery assembly: The appearance of the battery assembly prepared in Examples 1-45 was observed.

[0058] The test results are shown in Table 4.

[0059] Table 4

Claims

1. A main-grid-free integrated film for solar cells, characterized in that The integrated film includes a conventional film and a pretreated film, and the weight ratio of the pretreated film to the conventional film is (1-3):(3-1).

2. The integrated main-grid-free film for solar cells according to claim 1, wherein, The raw materials for preparing the pretreated film include, by weight: 100 parts of matrix resin, 0.5-2 parts of crosslinking agent, and 0.1-2 parts of co-crosslinking agent.

3. The integrated film without main grid for solar cells according to claim 2, wherein The matrix resin is selected from one or a combination of EVA matrix resin, POE matrix resin, and PVB matrix resin.

4. The main-grid-free integrated film for a solar cell according to claim 3, wherein, The specific gravity of the EVA matrix resin is 0.8 - 1.0 g / cm 3 , and its melt index at 190 °C under the condition of 2.16 kg is 12 - 26 g / 10 min; the specific gravity of the POE matrix resin is 0.8 - 1.0 g / cm 3 , and its melt index at 190 °C under the condition of 2.16 kg is 3 - 22 g / 10 min.

5. The integrated main-grid-free film for solar cells according to claim 2, wherein The crosslinking agent is a peroxide crosslinking agent, and the peroxide crosslinking agent is a tert-butyl peroxide-based crosslinking agent.

6. The integrated film without main grid for solar cells according to claim 1, characterized in that, The pre-crosslinking degree of the pretreated film is 10%-50%.

7. The integrated film without main grid for solar cells according to claim 6, wherein The pretreatment method of the pretreated film is selected from one or a combination of corona, electron irradiation, and ultraviolet irradiation; the crosslinking energy used for the electron irradiation pretreatment of the pretreated film is 10-80 kGy.

8. The integrated film without main grid for solar cell according to claim 1, characterized in that, The weight proportion of the pretreated film in the main-grid-free integrated film is 25%-75%.

9. A method for preparing the main-grid-free integrated film of a solar cell according to any one of claims 1-8, characterized in that, It includes the following steps: S1 Adopt an out-of-mold composite technology to composite the pretreated film and the conventional film; S2 Composite the cell on the surface of the pretreated film and composite the solar backplane or glass on the surface of the conventional film to obtain a cell module.

10. The preparation method of the main-grid-free integrated film for a solar cell according to claim 9, characterized in that, The technical parameters of the out-of-mold composite technology are as follows: mold temperature 80-100 °C; rubber roller temperature 0-50 °C; steel roller temperature 0-50 °C; traction speed 5-20 m / min.

Images