Optimization method for reliability test of photovoltaic cell

Abstract

The invention discloses a photovoltaic cell reliability test optimization method, and belongs to a photovoltaic cell test method in the technical field of solar photovoltaic power generation, the technical scheme is as follows: S1, warping degree test, S2, adhesive force test, S3, boiling experiment: putting the photovoltaic cell after the step S2 into deionized water for boiling operation, the boiling temperature is 70 DEG C, and the boiling time is 2-3 hours; the boiling time is 12-20 min, observing whether the surface of the photovoltaic cell generates bubbles with the deionized water or not, observing whether the appearance has obvious change or not, and recording; s4, a four-point bending test is carried out, specifically, the photovoltaic cell is horizontally placed in a four-point bending testing machine, and the bending test is carried out under the operation that the four-point bending testing machine is pressed down and moves at the speed of 0.05 mm / min to 0.1 mm / min; according to the optimization method for the reliability test of the photovoltaic cell, the accuracy of the test result is ensured, the use efficiency of the cell is improved, the test cost is reduced, and the economic benefit of the whole test work is improved.

Description

Technical Field

[0001] This invention belongs to the field of solar photovoltaic power generation technology, and specifically relates to an optimized method for reliability testing of photovoltaic cells. Background Technology

[0002] In recent years, photovoltaic (PV) roof tiles have gradually entered the photovoltaic (PV) market and are occupying an increasingly important position with an increasingly rapid development trend. PV roof tiles not only provide shelter from wind and rain but also absorb solar energy and convert it into electricity for people's daily lives and production. Furthermore, they can be perfectly integrated with the building itself, achieving true building-integrated photovoltaics (BIPV). Solar panels absorb sunlight and convert solar radiation energy directly or indirectly into electrical energy through the photoelectric effect or photochemical effect. Most solar panels are primarily made of silicon, and compared to ordinary batteries and rechargeable batteries, solar cells are more energy-efficient and environmentally friendly green products.

[0003] In the field of photovoltaic power generation technology, the stability of photovoltaic power generation largely depends on the performance of solar cells. Therefore, in existing technologies, performance testing is generally conducted on solar cells before they are put into use. However, existing testing methods for photovoltaic cell reliability testing suffer from resource waste and low efficiency. Conventional tensile testing uses Grade A cells, which is costly; simultaneously, multiple tests such as adhesion, warpage, four-point bending, and boiling water tests require a large number of cells, and the testing sequence is not always optimal, leading to excessive cell consumption, increased testing costs, and a negative impact on the efficiency of the testing process. Summary of the Invention

[0004] The purpose of this invention is to provide an optimized method for reliability testing of photovoltaic cells. This optimization improves the efficiency of cell utilization, reduces testing costs, and enhances the overall economic benefits of the testing work while ensuring the accuracy of test results.

[0005] The objective of this invention is achieved by providing an optimized method for reliability testing of photovoltaic cells, comprising the following steps: S1. Warpage test: Using C-grade photovoltaic cells with missing corners, the warpage is detected by a cell warpage detection device to make a preliminary judgment on the physical morphology of the photovoltaic cells. S2. Adhesion test: After completing the warpage test in S1, the photovoltaic cell is deformed and the deformation and electrical performance parameters of the cell are tested. The electrical performance parameters include voltage, resistance or current. S3. Boiling test: Put the photovoltaic cell sheets that have completed S2 into deionized water for boiling. The boiling temperature is 70°C, and the boiling time is 12 - 20 minutes. Observe whether there are bubbles generated between the surface of the photovoltaic cell sheets and the deionized water, and observe whether there are obvious changes in appearance, and record them. S4. Four-point bending test: Conduct a four-point bending test on the photovoltaic cell sheets after completing S3. Place the photovoltaic cell sheets horizontally in a four-point bending testing machine, and conduct a bending test under the operation of the four-point bending testing machine with a downward movement speed of 0.05 mm / min - 0.1 mm / min.

[0006] Furthermore, scan the surface of the photovoltaic cell sheets with a three-dimensional laser scanner, obtain point cloud data, construct a three-dimensional model of the photovoltaic cell sheets based on the point cloud data, and then calculate the height differences at different positions to determine the warpage degree of the photovoltaic cell sheets, with an accuracy of 0.01 mm.

[0007] Furthermore, place points A and B of the photovoltaic cell sheets in an electrical performance parameter testing device, perform a deformation operation on the photovoltaic cell sheets, and record the electrical performance parameters, deformation amounts, and corresponding adhesion strengths of the photovoltaic cell sheets.

[0008] Furthermore, in the boiling test, when bubbles are generated in the deionized water by the photovoltaic cell sheets, take out the photovoltaic cell sheets from the deionized water, dry them, and then observe and record the colors of the photovoltaic cell sheets.

[0009] Furthermore, conduct a conventional tensile test on the photovoltaic cell sheets before the warpage degree test. For the tensile test of N-type photovoltaic cell sheets, the tensile strength of the front side ≥ 1.25 N, the back side ≥ 1.5 N, and the single point ≥ 0.8 N are considered qualified.

[0010] Furthermore, in the warpage degree test, if the warpage degree of the photovoltaic cell sheets ≤ 1.00 mm, it is considered qualified.

[0011] Furthermore, in the four-point bending test, if the four-point bending strength value of the photovoltaic cell sheets ≥ 140 Mpa, it is considered qualified.

[0012] Furthermore, the C-grade corner-defective photovoltaic cell sheets are photovoltaic cell sheets with certain appearance defects but meeting the basic performance requirements.

[0013] The beneficial effects of the present invention are as follows: In the present invention, the test sequence is readjusted to "warpage degree - adhesion - boiling - four-point bending". After the test sequence is optimized, it is expected that about 8 pieces of cell sheets can be saved per shift, and about 240 pieces of cell sheets can be saved per month. Through this optimization, while ensuring the accuracy of the test results, the utilization efficiency of the cell sheets is improved, the test cost is reduced, and the economic benefits of the overall test work are enhanced. Detailed Implementation

[0014] The embodiments of the technical solution of the present invention will be described in detail below. These embodiments are only used to illustrate the technical solution of the present invention more clearly, and are therefore merely examples and should not be used to limit the scope of protection of the present invention.

[0015] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0016] An optimized method for reliability testing of photovoltaic cells includes the following steps: S1. Warpage Test: Using C-grade photovoltaic cells with missing corners, the warpage of the photovoltaic cells is detected by a cell warpage detection device to make a preliminary judgment on the physical morphology of the photovoltaic cells. The warpage test is performed first because it is relatively simple and causes less damage to the cells. By detecting the degree of warpage of the cells, it is possible to make a preliminary judgment on whether the physical morphology of the cells meets the requirements. Valid data can be obtained using a small number of cell samples. S2. Adhesion Test: After completing the warpage test in S1, the photovoltaic cell is deformed, and the deformation and electrical performance parameters of the cell are tested, including voltage, resistance, or current. Following the warpage test, an adhesion test is performed. At this point, the cell remains largely intact, allowing for a relatively accurate test of the adhesion between the cell's surface coating and the substrate. This test will not cause irreversible damage to the cell and it can be used for subsequent tests. S3. Boiling Test: The photovoltaic cells from S2 are immersed in deionized water at 70℃ for 12-20 minutes. Observe whether bubbles form on the surface of the photovoltaic cells with the deionized water, and record any significant changes in appearance. This simulates the performance changes of the cells under a specific temperature environment. Cells that have passed the previous two tests still effectively demonstrate their performance in the boiling test, and even after boiling, their remaining strength and other properties still support the final test. S4. Four-point bending test: After completing S3, perform a four-point bending test on the photovoltaic cell. Place the photovoltaic cell horizontally in a four-point bending testing machine and conduct a bending test under the condition that the downward moving speed of the four-point bending testing machine is 0.05 mm / min - 0.1 mm / min. Finally, perform a four-point bending test. This test has relatively high requirements for the mechanical strength of the cell. For the cells after the previous tests, if they can pass the four-point bending test, the comprehensive performance of the cells under various conditions can be fully reflected. After optimization, the 4 tests that originally required 4 cells can now be completed with 1 - 2 cells.

[0017] Preferably, scan the surface of the photovoltaic cell with a three-dimensional laser scanner, obtain point cloud data, construct a three-dimensional model of the photovoltaic cell based on the point cloud data, and then calculate the height differences at different positions to determine the warpage degree of the photovoltaic cell with an accuracy of 0.01 mm.

[0018] Preferably, place two points A and B of the photovoltaic cell in an electrical performance parameter testing device, perform deformation operations on the photovoltaic cell, and record the electrical performance parameters, deformation amounts, and corresponding adhesion strengths of the photovoltaic cell.

[0019] Preferably, in the boiling water experiment, when bubbles are generated in the deionized water for the photovoltaic cell, take the photovoltaic cell out of the deionized water, dry it, and then observe and record the color of the photovoltaic cell.

[0020] Preferably, conduct a conventional tensile test on the photovoltaic cell before the warpage degree test. For the tensile test of N-type photovoltaic cells, the requirements are as follows: the front side ≥ 1.25 N, the back side ≥ 1.5 N, and a single point ≥ 0.8 N, which is considered qualified.

[0021] Preferably, in the warpage degree test, if the warpage degree of the photovoltaic cell ≤ 1.00 mm, it is considered qualified.

[0022] Preferably, in the four-point bending test, if the four-point bending strength value of the photovoltaic cell ≥ 140 Mpa, it is considered qualified.

[0023] Preferably, the C-level chipped photovoltaic cells are photovoltaic cells with certain appearance defects but meeting the basic performance requirements; by replacing the cell types, about 20 pcs of cells can be saved per shift, and about 600 pcs of cells can be saved per month. After optimizing the test sequence, about 8 pcs of cells can be saved per shift, and about 240 pcs of cells can be saved per month. In 2024, a total of about 10080 pcs of cells were saved for the company, effectively reducing the test cost, improving the utilization efficiency of the cells, and enhancing the economic benefits of the overall test work while ensuring the accuracy of the test results.

[0024] Before optimization The photovoltaic cells are tested by five test steps: conventional tensile force, boiling water test, warpage, four-point bending and adhesion. At the same time, A-grade photovoltaic cells are used for welding test. During the boiling water test, warpage, four-point bending and adhesion tests, 1 A-grade photovoltaic cell is required. Current situation analysis: For multiple test items such as original adhesion, warpage, four-point bending, and boiling water test, the demand for cells is large, and the test sequence is not reasonable. For example, previously, after some tests, the cells may have been severely damaged, but some relatively more suitable tests were not carried out first, resulting in the need for additional cells to complete subsequent tests, consuming too many cells.

[0025] Example 1 An optimization method for the reliability test of photovoltaic cells includes the following steps: First, conduct a conventional tensile force test on the photovoltaic cells. For the tensile force test of N-type photovoltaic cells, the requirements are: the front side ≥ 1.35 N, the back side ≥ 1.6 N, and a single point ≥ 0.8 N, which is considered qualified. S1. Warpage test: Use C-grade corner-deficient photovoltaic cells to detect the warpage through a cell warpage detection device. Scan the surface of the photovoltaic cell with a three-dimensional laser scanner to obtain point cloud data. Based on the point cloud data, construct a three-dimensional model of the photovoltaic cell, and then calculate the height differences at different positions to determine the warpage of the photovoltaic cell with an accuracy of 0.01 mm. In the warpage test, the warpage of the photovoltaic cell ≤ 1.00 mm to make a preliminary physical form judgment of the photovoltaic cell. Conduct the warpage test first because this test is relatively simple and causes less damage to the cells. By detecting the warpage degree of the cells, the physical form of the cells can be preliminarily judged whether it meets the requirements, and effective data can be obtained with fewer cell samples; S2. Adhesion test: After completing the warpage test of S1, perform a deformation operation on the photovoltaic cell. Place two points A and B of the photovoltaic cell in an electrical performance parameter test device, perform a deformation operation on the photovoltaic cell, and record the electrical performance parameters, deformation amount, and corresponding adhesion force of the photovoltaic cell, and test the deformation amount and electrical performance parameters of the cell. The electrical performance parameters include voltage, resistance, or current. After completing the warpage test, conduct the adhesion test. At this time, the cell is basically in a complete state, and the adhesion ability between the surface coating of the cell and the substrate can be accurately tested. This test will not cause irreparable damage to the cell and can be continued for subsequent tests; S3. Boiling water test: Put the photovoltaic cell sheets that have completed S2 into deionized water for boiling. The boiling temperature is 70°C and the boiling time is 12 minutes. Observe whether bubbles are generated between the surface of the photovoltaic cell sheets and the deionized water, and observe whether there are obvious changes in the appearance, and make records. Then conduct the boiling water test to simulate the performance change of the cell sheets under a certain temperature environment. The cell sheets that have passed the previous two tests can still effectively reflect the relevant performance in the boiling water test, and even after boiling, the remaining strength of the cell sheets can still support the last test; S4. Four-point bending test: Conduct a four-point bending test on the photovoltaic cell sheets that have completed S3. Place the photovoltaic cell sheets horizontally in a four-point bending testing machine and conduct a bending test under the condition that the downward moving speed of the four-point bending testing machine is 0.05 mm / min. In the four-point bending test, if the four-point bending strength value of the photovoltaic cell sheets ≥ 140 Mpa, it is considered qualified. Finally, conduct the four-point bending test. This test has relatively high requirements for the mechanical strength of the cell sheets. If the cell sheets can pass the four-point bending test after the previous tests, it can comprehensively reflect the comprehensive performance of the cell sheets under various conditions. After optimization, the 4 tests that originally required 4 cell sheets can now be completed with 2 cell sheets.

[0026] Example 2 An optimization method for the reliability test of photovoltaic cell sheets includes the following steps: First, conduct a conventional tensile test on the photovoltaic cell sheets. For the tensile test of N-type photovoltaic cell sheets, if the front side ≥ 1.55 N, the back side ≥ 1.8 N, and the single point ≥ 0.8 N, it is considered qualified. S1. Warpage test: Use photovoltaic cell sheets with C-level chamfers and detect the warpage through a cell sheet warpage detection device. Scan the surface of the photovoltaic cell sheets with a three-dimensional laser scanner to obtain point cloud data, construct a three-dimensional model of the photovoltaic cell sheets based on the point cloud data, and then calculate the height differences at different positions to determine the warpage of the photovoltaic cell sheets with an accuracy of 0.01 mm. In the warpage test, if the warpage of the photovoltaic cell sheets ≤ 1.00 mm, conduct a preliminary physical form judgment on the photovoltaic cell sheets. Conduct the warpage test first because this test is relatively simple and causes less damage to the cell sheets. By detecting the warpage degree of the cell sheets, it can be preliminarily judged whether the physical form of the cell sheets meets the requirements, and effective data can be obtained with fewer cell sheet samples; S2. Adhesion Test: After completing the warpage test in S1, the photovoltaic cell is deformed. Points A and B of the photovoltaic cell are placed in the electrical performance parameter testing device, and the photovoltaic cell is deformed. The electrical performance parameters, deformation amount, and corresponding adhesion force of the photovoltaic cell are recorded. The deformation amount and electrical performance parameters of the cell are tested, including voltage, resistance, or current. After completing the warpage test, the adhesion test is performed. At this time, the cell is basically intact, which can accurately test the adhesion ability between the coating on the cell surface and the substrate. This test will not cause irreversible damage to the cell and can be used for subsequent tests. S3. Boiling Test: The photovoltaic cells from S2 were immersed in deionized water at 70℃ for 16 minutes. Observation was conducted to check for bubble formation on the surface of the cells and any noticeable changes in appearance, which were recorded. This simulated the performance changes of the cells under specific temperature conditions. Cells that passed the first two tests still exhibited good performance in the boiling test, and even after boiling, their remaining strength and other properties supported the final test. S4, Four-point Bending Test: After completing S3, the photovoltaic cells undergo a four-point bending test. The photovoltaic cells are placed horizontally in a four-point bending tester, and the bending test is performed while the machine is running at a downward moving speed of 0.08 mm / min. In the four-point bending test, the photovoltaic cell is considered qualified if the four-point bending strength value is ≥140 MPa. This final four-point bending test places high demands on the mechanical strength of the cells. If the cells pass the four-point bending test after the previous tests, it can comprehensively reflect the overall performance of the cells under various conditions. After optimization, the four tests that originally required four cells can now be completed with only two cells.

[0027] Example 3 An optimized method for reliability testing of photovoltaic cells includes the following steps: First, conduct a conventional tensile test on the photovoltaic cell. For the tensile test of N-type photovoltaic cells, the requirements are as follows: the front side ≥ 1.65 N, the back side ≥ 1.6 N, and a single point ≥ 0.8 N, which is considered qualified. S1, warpage test: Use photovoltaic cells with C-level corner defects. Detect the warpage of the photovoltaic cells through a cell warpage detection device. Scan the surface of the photovoltaic cells using a three-dimensional laser scanner and obtain point cloud data. Based on the point cloud data, construct a three-dimensional model of the photovoltaic cells, and then calculate the height differences at different positions to determine the warpage of the photovoltaic cells with an accuracy of 0.01 mm. In the warpage test, the warpage of the photovoltaic cells ≤ 1.00 mm, and a preliminary physical form judgment of the photovoltaic cells is carried out. Conducting the warpage test first is because this test is relatively simple and causes less damage to the cells. By detecting the warpage degree of the cells, it can be preliminarily judged whether the physical form of the cells meets the requirements, and effective data can be obtained using fewer cell samples. S2, adhesion test: After completing the warpage test in S1, perform a deformation operation on the photovoltaic cell. Place two points A and B of the photovoltaic cell in an electrical performance parameter test device, perform a deformation operation on the photovoltaic cell, and record the electrical performance parameters, deformation amount, and corresponding adhesion force of the photovoltaic cell, and test the deformation amount and electrical performance parameters of the cell. The electrical performance parameters include voltage, resistance, or current. After completing the warpage test, conduct the adhesion test. At this time, the cell is basically in a complete state, and the adhesion ability between the surface coating of the cell and the substrate can be accurately measured. This test will not cause irreparable damage to the cell and can be continued for subsequent tests. S3, boiling water experiment: Place the photovoltaic cell that has completed S2 into deionized water for boiling. The boiling temperature is 70 °C, and the boiling time is 20 min. Observe whether there are bubbles generated between the surface of the photovoltaic cell and the deionized water, and observe whether there are obvious changes in the appearance and record them. Then conduct the boiling water experiment to simulate the performance change of the cell under a certain temperature environment. The cells that have undergone the previous two tests can still effectively reflect the relevant performance in the boiling water experiment, and even after boiling, the remaining strength of the cells can still support the last test. S4, Four-point Bending Test: After completing S3, the photovoltaic cells undergo a four-point bending test. The photovoltaic cells are placed horizontally in a four-point bending test machine, and the bending test is performed while the machine is running at a downward moving speed of 0.1 mm / min. In the four-point bending test, the photovoltaic cell is considered qualified if the four-point bending strength value is ≥140 MPa. This final four-point bending test requires high mechanical strength from the cells. If the cells pass the four-point bending test after the previous tests, it can comprehensively reflect the overall performance of the cells under various conditions. After optimization, the four tests that originally required four cells can now be completed with only two cells.

[0028] By replacing the type of solar cell, approximately 20 cells can be saved per shift, resulting in a monthly saving of approximately 600 cells. After optimizing the testing sequence, approximately 8 cells can be saved per shift, resulting in a monthly saving of approximately 240 cells. In 2024, this resulted in a total cost saving of approximately 10,080 cells for the company, effectively reducing testing costs, improving cell utilization efficiency, and enhancing the overall economic benefits of testing operations while ensuring the accuracy of test results.

[0029] The average electrical performance data for the three batches of solar cells are obtained below.

[0030] Table 1 ; Where Eta is the conversion efficiency (%), Uoc is the open-circuit voltage (mV), Isc is the short-circuit current (A), FF is the fill factor, Rs is the series resistance (Ω), and Rsh is the parallel resistance (Ω).

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. An optimized method for reliability testing of photovoltaic cells, characterized in that, It includes the following steps: S1. Warpage test: Use photovoltaic cells with C-level corner defects to detect the warpage through a warpage detection device for photovoltaic cells, and make a preliminary judgment on the physical form of the photovoltaic cells. S2. Adhesion test: After completing the warpage test in S1, perform deformation operations on the photovoltaic cells, and test the deformation amount and electrical performance parameters of the cells. The electrical performance parameters include voltage, resistance or current. S3. Boiling test: Put the photovoltaic cells that have completed S2 into deionized water for boiling. The boiling temperature is 70°C, and the boiling time is 12 - 20 min. Observe whether bubbles are generated between the surface of the photovoltaic cells and the deionized water, and observe whether there are obvious changes in appearance, and record them. S4. Four-point bending test: Perform a four-point bending test on the photovoltaic cells after completing S3. Place the photovoltaic cells horizontally in a four-point bending testing machine, and conduct a bending test under the operation of the four-point bending testing machine with a downward movement speed of 0.05 mm / min - 0.1 mm / min.

2. The optimized method for photovoltaic cell reliability testing according to claim 1, characterized in that, Scan the surface of the photovoltaic cells through a three-dimensional laser scanner, obtain point cloud data, construct a three-dimensional model of the photovoltaic cells based on the point cloud data, and then calculate the height differences at different positions to determine the warpage of the photovoltaic cells, with an accuracy of 0.01 mm.

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