Method and device for testing thermal attenuation of photovoltaic cell

Abstract

The invention provides a photovoltaic cell thermal attenuation test method and device, and belongs to the technical field of solar cells, and the method comprises the steps: randomly selecting a plurality of to-be-tested cells, and carrying out the first performance test one by one; the method comprises the following steps of: simulating the environment temperature during lamination in a test box, placing a photovoltaic module to be laminated in the test box for simulating lamination to perform a thermal attenuation test, performing a second performance test, and determining the performance change of a battery piece to be tested according to a first performance test result and a second performance test result; if yes, the batch of battery pieces are judged to be qualified, and lamination production can be carried out; if the number of unqualified battery pieces exceeds 5% of the sampling inspection number, it is judged that the battery pieces in the batch are unqualified, and lamination production is not suitable for being carried out. Before the photovoltaic module enters the lamination process, unqualified batches of battery pieces are removed in time, loss is stopped in time, cost and resource waste are reduced, and a basis can be provided for improvement of the subsequent lamination process.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells, and in particular relates to a method and device for testing thermal attenuation of a photovoltaic cell. Background Art

[0002] Photovoltaic modules are devices that use solar radiation to convert light energy into electrical energy. Photovoltaic cells, as the most important component of photovoltaic modules, are semiconductor components that can effectively absorb sunlight and convert it into electrical energy. The performance of photovoltaic cells directly affects the power generation efficiency and economy of the photovoltaic system.

[0003] In the process of preparing photovoltaic modules, a lamination process is required. This process requires heating and pressurizing the photovoltaic modules. After the battery cells are exposed to high temperatures, thermal decay will occur. Tests are required to determine the performance of the battery cells after thermal decay to determine whether the photovoltaic modules meet the requirements after high-temperature lamination. If they do not meet the requirements, the photovoltaic modules need to be scrapped, and the raw materials of the battery cells and the EVA, backplane, solder ribbon, busbar, flux, etc. that encapsulate the battery cells are wasted, resulting in a waste of costs and resources.

[0004] How to prevent problems in the lamination process and reduce the cost and resource waste of photovoltaic production enterprises has become an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0005] The embodiments of the present invention provide a method and device for testing thermal attenuation of photovoltaic cells. By simulating the lamination process, thermal attenuation tests are performed on different batches of cells, and the performance of the batch of cells after thermal attenuation is pre-judged. Before the photovoltaic module enters the lamination process, unqualified batches of cells are promptly removed to stop losses in time, thereby reducing the waste of costs and resources caused by thermal attenuation detection after lamination, and providing a basis for improving subsequent lamination processes.

[0006] In the first aspect, in order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: to provide a photovoltaic cell thermal attenuation test method, the method comprising: A plurality of cells to be tested are randomly selected, and a first performance test is performed one by one on the cells. The first performance test includes an EL test and a power test under STC standard test conditions. The EL test results are recorded in sequence as: EL1-1, EL2-1...ELn-1, and the power test results are recorded in sequence as: P1-1, P2-1...Pn-1, where n is a positive integer representing the number and number of cells to be tested; According to the number of cells to be tested, a photovoltaic module to be laminated of corresponding area is formed; The test box simulates the ambient temperature during lamination, and the photovoltaic modules to be laminated are placed in the test box to simulate lamination and conduct thermal attenuation test; Take out the battery cell to be tested and conduct the second performance test. The EL test results are recorded in sequence as: EL1-2, EL2-2...ELn-2, ​​and the power test results are recorded in sequence as: P1-2, P2-2...Pn-2; According to the first performance test result and the second performance test result, the performance change of the battery cell to be tested is determined: When |P1-P2| / P1≤0.01, it indicates that the power of the cell to be tested is stable. At this time, it is considered that the cell to be tested is not sensitive to the preset temperature and the photovoltaic module can be laminated and generated; When 0.01<|P1-P2| / P1≤0.1, it means that the cell to be tested is sensitive to the preset temperature and the lamination temperature should be adjusted; When 0.1<|P1-P2| / P1, it means that the cell to be tested is very sensitive to the preset temperature and cannot be used for photovoltaic module lamination production; Compare the results before and after the EL test. Through image comparison, if there are cracks or fragments in the cell, the cell to be tested is judged to be unqualified and cannot be used for photovoltaic module lamination production; When the performance parameters of the sampled battery cells are consistent, the batch of battery cells is judged to be qualified and can be laminated for production; if the number of unqualified battery cells exceeds 5% of the sampled number, the batch of battery cells is judged to be unqualified and is not suitable for lamination production.

[0007] In combination with the first aspect, in one achievable manner, the test box simulates the ambient temperature during lamination, and the photovoltaic components to be laminated are placed in the test box to simulate lamination for a thermal attenuation test, including: preheating the test box to a lamination temperature of 135-145°C, keeping it warm for 20 minutes, and then naturally cooling it to 25°C.

[0008] In combination with the first aspect, in an achievable manner, the step of forming a photovoltaic assembly to be laminated of a corresponding area according to the number of cells to be tested selected includes: According to the area of ​​the photovoltaic modules to be laminated corresponding to the number of cells to be tested, the weight of the raw materials required for the corresponding photovoltaic modules to be laminated is calculated, and the required raw materials include EVA, back sheet, solder ribbon, busbar, and flux; Apply flux to the surface of the solder ribbon and the busbar, and then lay EVA, the solder ribbon and busbar with flux, EVA and the backplane on the non-light-receiving surface of the glass in turn.

[0009] In combination with the first aspect, in one achievable manner, the vacuum degree in the test chamber is less than or equal to 100 Pa.

[0010] In the second aspect, an embodiment of the present invention further provides a photovoltaic cell thermal attenuation testing device, the device comprising a test box, wherein the test box is provided with a heating unit, an air circulation unit and a laminating mechanism for laminating photovoltaic components to be laminated, and the test box is provided with a vacuum pipe for extracting a vacuum.

[0011] In combination with the second aspect, in one achievable manner, the heating unit includes a lower heating plate disposed at a lower portion of the test box and an upper heating plate disposed at an upper portion of the test box, and the laminating mechanism is disposed between the upper heating plate and the lower heating plate.

[0012] In combination with the second aspect, in one achievable manner, the lamination mechanism includes a substrate, a laminating plate, and a linear driving unit for driving the laminating plate toward the substrate, and the photovoltaic components to be laminated are laminated between the laminating plate and the substrate by the linear driving unit.

[0013] In combination with the second aspect, in one achievable manner, the inner walls opposite to the test box are provided with guide grooves for inserting the substrate, the linear drive unit is supported by beams fixed at both ends to the inner walls of the test box, and the laminate is mounted on the linear drive unit.

[0014] In combination with the second aspect, in one achievable manner, both the substrate and the laminate are stainless steel mesh plates.

[0015] In combination with the second aspect, in one achievable manner, the air circulation unit includes a fan, and the fan is disposed between the laminating mechanism and the upper heating plate.

[0016] The photovoltaic cell thermal attenuation testing method and device provided by the present invention have the following beneficial effects compared with the prior art: the photovoltaic cell thermal attenuation testing device of the present invention can simulate the degree of thermal attenuation of the cell under the temperature environment of a laminator, and the cell is taken out after the test for performance testing, so as to obtain the performance parameters of the cell before and after lamination, and determine whether the electrical performance of the cell after lamination is qualified and whether it can enter the lamination process through two performance tests before and after the test, and before the photovoltaic module enters the lamination process, and unqualified batches of cells are promptly removed to stop losses in time, thereby reducing the waste of costs and resources caused by thermal attenuation detection after lamination.

[0017] The testing method of the present invention is simple and quick, does not require the preparation of test samples of the packaging structure, can quickly and effectively simulate the performance attenuation of photovoltaic cells during temperature changes, can be well in line with reality, and provides parameter performance assistance for the improvement of subsequent lamination process technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1A schematic diagram of the structure of a photovoltaic cell thermal attenuation testing device provided by an embodiment of the present invention; Description of reference numerals: 1. Test chamber; 2. Upper heating plate; 3. Air circulation unit; 4. Vacuum tube; 5. Lower heating plate; 6. Substrate; 7. Photovoltaic module; 8. Laminate; 9. Linear drive unit; 10. Crossbeam. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] See also Figure 1 The photovoltaic cell thermal attenuation test method provided by the present invention is now described. The photovoltaic cell thermal attenuation test method comprises the following steps: Cell performance test Step 1, randomly select 10 battery cells to be tested, and perform the first performance test on the battery cells to be tested, including EL test and power test under STC standard test conditions, and record the EL test results in sequence as: EL1-1, EL2-1...EL10-1, and the power test results in sequence as: P1-1, P2-1...P10-1, where n is a positive integer, representing the number and number of battery cells to be tested.

[0021] Step 2: Calculate the weight of the raw materials used, including EVA, backplane, solder ribbon, busbar, flux, etc., based on the component area corresponding to the number of battery cells.

[0022] Step 3: Apply flux on the surface of the solder ribbon, and then lay EVA, the solder ribbon with flux (bus ribbon), EVA and the backplane on the non-light-receiving surface of the glass in turn.

[0023] Step 4, first raise the temperature in the test box 1 to 135-145°C, place the glass containing raw materials on the substrate 6, and drive the laminate 8 to press the glass and the materials laid on the glass through the linear drive unit 9. The operation process is controlled within 1-2 minutes.

[0024] Step 5: Evacuate the environmental test chamber 1 to a vacuum degree of less than or equal to 100 Pa.

[0025] Step 6: Maintain the temperature in the test chamber 1 at 135-145°C, and keep it warm for 20 minutes before naturally cooling it down to 25°C after thermal decay. Step seven, take out the processed battery cells to be tested, and perform a second performance test on the battery cells to be tested, including EL test and power test under STC standard test conditions. The EL test results are recorded as: EL1-2, EL2-2...EL10-2, and the power test results are recorded as: P1-2, P2-2...P10-2. Determine the change in electrical performance of the cell to be tested according to the first performance test result and the second performance test result: Step eight, when |P1-P2| / P1≤0.01, it indicates that the power of the tested cell is stable. At this time, it is considered that the tested cell is not sensitive to the preset temperature, and the photovoltaic module 7 can be laminated and generated; When 0.01<|P1-P2| / P1≤0.1, it means that the cell to be tested is sensitive to the preset temperature and the lamination temperature should be adjusted; When 0.1<|P1-P2| / P1, it means that the cell to be tested is very sensitive to the preset temperature and cannot be used for photovoltaic module 7 lamination production; Step nine, comparing the results before and after the EL test, through image comparison, if there are cracks or fragments in the cell, it is judged that the cell to be tested is unqualified and cannot be used for photovoltaic module 7 lamination production; Step 10: When the performance parameters of the sampled battery cells are consistent, the battery cells in this batch are judged to be qualified and can be laminated for production; if the number of unqualified battery cells exceeds 5% of the sampled number, the battery cells in this batch are judged to be unqualified and are not suitable for lamination production.

[0026] It is noted that the EL (electroluminescence) test of photovoltaic cells is mainly used to detect internal defects such as cracks, fragments and hidden cracks, and usually does not directly provide numerical results, but evaluates the quality of the cell through image analysis. Characteristics of EL test results: Image format: Results are presented as an image, with bright areas representing normal power generation and dark areas possibly indicating defects.

[0027] Qualitative analysis: By comparing images, determine whether there are any problems with the battery, such as cracks, fragments, etc.

[0028] No direct numerical value: The EL test itself does not generate specific numerical values, but relies more on image analysis.

[0029] The embodiment of the present invention also provides a photovoltaic cell thermal attenuation test device for testing the performance of the cell after thermal attenuation. Figure 1 As shown, the device includes a test box 1, in which a heating unit, an air circulation unit 3 and a laminating mechanism for laminating photovoltaic components 7 to be laminated are arranged, and a vacuum pipe 4 for extracting a vacuum is arranged on the test box 1.

[0030] The heating unit is used to simulate the temperature required for lamination in the test, and the vacuum environment required for lamination is provided for the test by vacuum extraction. The lamination mechanism is used to support the photovoltaic module 7, and the air circulation unit 3 is used for rapid circulation of the environment in the test box 1 to maintain temperature balance.

[0031] In some embodiments, see Figure 1 As shown, the heating unit includes a lower heating plate 5 arranged at the lower part of the test box 1 and an upper heating plate 2 arranged at the upper part of the test box 1, and the laminating mechanism is arranged between the upper heating plate 2 and the lower heating plate 5. By heating the photovoltaic module 7 from top to bottom, the battery cells are heated evenly. The lower heating plate 5 can be heated by electricity or oil; the upper heating plate 2 is in the form of an electric heating wire, an electric heating tube or an electric heating plate.

[0032] In some embodiments, see Figure 1 As shown, the laminating mechanism includes a substrate 6, a laminating plate 8, and a linear driving unit 9 for driving the laminating plate 8 to approach the substrate 6, and the photovoltaic module 7 to be laminated is laminated between the laminating plate 8 and the substrate 6 through the linear driving unit 9. Among them, the substrate 6 can be arranged horizontally or vertically, and the laminating plate 8 is parallel to the substrate 6. The laminating plate 8 is driven by the linear driving unit 9 to move linearly to adjust the distance between the laminating plate 8 and the substrate 6.

[0033] The linear drive unit 9 is an electric push rod, a pneumatic cylinder or a hydraulic cylinder.

[0034] In some embodiments, see Figure 1 As shown, the inner walls opposite to each other of the test box 1 are provided with guide grooves for plugging in the substrate 6, the linear drive unit 9 is supported by a beam 10 fixed to the inner wall of the test box 1 at both ends, and the laminate 8 is mounted on the linear drive unit 9. The linear drive unit 9 is located above the center of the laminate 8. The guide groove is provided to facilitate the insertion and removal of the substrate 6 and the assembly of the substrate 6. The laminate 8 is driven by the linear drive unit 9 to perform linear movement, and the length and width of the laminate 8 are consistent with the size of the substrate 6. A door is provided on the side of the test box 1 to facilitate the placement and removal of the photovoltaic module 7.

[0035] Optionally, a horizontal beam 10 and a longitudinal beam are arranged in the test box, and linear drive units 9 are symmetrically arranged on the horizontal beam and the longitudinal beam with the intersection of the horizontal beam and the longitudinal beam as the center. The linear drive units 9 are distributed at the four vertices of the rectangle, connecting the laminate 8 at four points, thereby improving the balance of the compression force on the laminated photovoltaic component 7.

[0036] In some embodiments, the substrate 6 and the laminate 8 are both stainless steel mesh plates, which can ensure temperature cycling and prevent wind damage to the solar cells.

[0037] In some embodiments, see Figure 1As shown, the air circulation unit 3 includes a fan, which is arranged between the laminating mechanism and the upper heating plate 2. Specifically, a pair of fans are arranged 20 cm below the upper heating plate 2, and the fans are fixed on the side wall of the test box 1.

[0038] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[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 and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for testing thermal attenuation of photovoltaic cells, characterized in that: The method comprises: A plurality of cells to be tested are randomly selected, and a first performance test is performed one by one on the cells. The first performance test includes an EL test and a power test under STC standard test conditions. The EL test results are recorded in sequence as: EL1-1, EL2-1...ELn-1, and the power test results are recorded in sequence as: P1-1, P2-1...Pn-1, where n is a positive integer representing the number and number of cells to be tested; According to the number of cells to be tested, a photovoltaic assembly (7) to be laminated with a corresponding area is formed; The test box (1) simulates the ambient temperature during lamination, and the photovoltaic module (7) to be laminated is placed in the test box (1) to simulate lamination and perform a thermal attenuation test; Take out the battery cell to be tested and conduct the second performance test. The EL test results are recorded in sequence as: EL1-2, EL2-2...ELn-2, ​​and the power test results are recorded in sequence as: P1-2, P2-2...Pn-2; According to the first performance test result and the second performance test result, the performance change of the battery cell to be tested is determined: When |P1-P2| / Pn1≤0.01, it indicates that the power of the cell to be tested is stable. At this time, it is considered that the cell to be tested is not sensitive to the preset temperature, and the photovoltaic module (7) can be laminated and generated; When 0.01<|P1-P2| / P1≤0.1, it means that the cell to be tested is sensitive to the preset temperature and the lamination temperature should be adjusted; When 0.1<|P1-P2| / P1, it means that the cell to be tested is very sensitive to the preset temperature and cannot be used for lamination production of photovoltaic modules (7); Comparing the results before and after the EL test, through image comparison, if there are cracks or fragments in the cell, the cell to be tested is judged to be unqualified and cannot be used for the lamination production of photovoltaic modules (7); When the performance parameters of the sampled battery cells are consistent, the batch of battery cells is judged to be qualified and can be laminated for production; if the number of unqualified battery cells exceeds 5% of the sampled number, the batch of battery cells is judged to be unqualified and is not suitable for lamination production.

2. The photovoltaic cell thermal attenuation test method according to claim 1, characterized in that: The test box (1) simulates the ambient temperature during lamination, and the photovoltaic module (7) to be laminated is placed in the test box (1) to simulate lamination and perform a thermal attenuation test, including: preheating the test box (1) to a lamination temperature of 135-145°C, keeping the temperature for 20 minutes, and then naturally cooling to 25°C.

3. The photovoltaic cell thermal attenuation test method according to claim 1, characterized in that: The photovoltaic assembly (7) to be laminated with a corresponding area formed according to the number of cells to be tested selected comprises: According to the selected photovoltaic assemblies (7) to be laminated with an area corresponding to the number of cells to be tested, the weight of the raw materials required for the corresponding photovoltaic assemblies (7) to be laminated is calculated, and the required raw materials include EVA, back sheet, solder strip, busbar, and flux; Apply flux to the surface of the solder ribbon and the busbar, and then lay EVA, the solder ribbon and busbar with flux, EVA and the backplane on the non-light-receiving surface of the glass in turn.

4. The photovoltaic cell thermal attenuation test method according to claim 1, characterized in that: The vacuum degree in the test box (1) is less than or equal to 100 Pa.

5. A photovoltaic cell thermal attenuation testing device, used in the photovoltaic cell thermal attenuation testing method according to any one of claims 1 to 4, characterized in that: The device comprises a test box (1), wherein a heating unit, an air circulation unit (3) and a laminating mechanism for laminating photovoltaic components (7) to be laminated are arranged inside the test box (1), and a vacuum pipe (4) for extracting a vacuum is arranged on the test box (1).

6. The photovoltaic cell thermal attenuation testing device according to claim 5, characterized in that: The heating unit comprises a lower heating plate (5) arranged at the lower part of the test box (1) and an upper heating plate (2) arranged at the upper part of the test box (1), and the laminating mechanism is arranged between the upper heating plate (2) and the lower heating plate (5).

7. The photovoltaic cell thermal attenuation testing device according to claim 6, characterized in that: The laminating mechanism comprises a substrate (6), a laminating plate (8), and a linear driving unit (9) for driving the laminating plate (8) to move toward the substrate (6); the photovoltaic component (7) to be laminated is laminated between the laminating plate (8) and the substrate (6) by the linear driving unit (9).

8. The photovoltaic cell thermal attenuation testing device according to claim 7, characterized in that: The inner walls opposite to the test box (1) are provided with guide grooves for inserting the base plate (6); the linear drive unit (9) is supported by a crossbeam (10) fixed at both ends to the inner wall of the test box (1); and the laminate (8) is mounted on the linear drive unit (9).

9. The photovoltaic cell thermal attenuation testing device according to claim 7, characterized in that: The substrate (6) and the laminate (8) are both stainless steel mesh plates.

10. The photovoltaic cell thermal attenuation testing device according to claim 6, characterized in that: The air circulation unit (3) comprises a fan, which is arranged between the laminating mechanism and the upper heating plate (2).

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