A test method for detecting the acid resistance of double-sided solar cells

Abstract

The present invention provides a test method for detecting the acid resistance of double-sided solar cells, comprising the following steps: (1) performing EL image and electrical performance tests on the solar cells, placing a partition in a container containing an acetic acid solution with a certain concentration, placing the solar cells on the partition, sealing the container and placing it in a constant temperature device; (2) dividing the solar cells into groups according to the placement time, taking out the solar cells placed for different times and testing the EL images, testing the electrical performance of the solar cells with no abnormal appearance in the EL images, and calculating the attenuation value; (3) performing contact resistance tests on the solar cells with an attenuation value > 15%, and judging the acid corrosion resistance of the front and back sides of the solar cells through the resistance. In the test method for detecting the acid resistance of double-sided solar cells of the invention, contact resistance tests are performed on the solar cells with a large attenuation value after acetic acid testing. By testing the magnitudes of the front and back contact resistances, it can be determined which side has a large contact resistance, and then which side is more affected by acetic acid corrosion, thus shortening the detection time at the battery end.

Description

Technical Field

[0001] The present invention relates to the field of manufacturing crystalline silicon solar cells, and particularly to a test method for detecting the acid resistance of double-sided battery wafers. Background Art

[0002] Currently, to detect the long-term ability of components to resist moisture erosion, a damp heat test needs to be conducted, which generally takes at least 1000 hours (about 42 days). This test takes too long, and if the experimental results show a large attenuation, it is impossible to determine which side of the double-sided battery wafer causes it; on rainy days and days with high air humidity, the pH value in the air is < 7, showing acidity, that is, the ability of the component to resist moisture erosion mainly depends on the acid corrosion resistance of the component, and the acid corrosion resistance is mainly related to the paste on the battery wafer and the backplane of the component. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a test method for detecting the acid resistance of double-sided battery wafers. At the battery end, in order to shorten the detection time, the acetic acid test can be carried out on the battery wafer to shorten the time, and through the contact resistance test, it can be confirmed which side of the double-sided battery has problems, so as to carry out targeted improvement. The technical solution adopted by the present invention is:

[0004] A test method for detecting the acid resistance of double-sided battery wafers, which includes the following steps:

[0005] (1) Perform EL image and electrical performance tests on the battery wafer. Place a partition in a container filled with acetic acid solution, and place the battery wafer after the EL image and electrical performance tests on the partition. Then seal the container and place it in a constant temperature device;

[0006] (2) Group the battery wafers according to the placement time. Take out the battery wafers placed for different times and test their EL images, and compare them with the EL image in step (1). Test the electrical performance of the battery wafers with no abnormal appearance after the EL image comparison, and then compare the electrical performance of the battery wafers with the electrical performance in step (1) to calculate the attenuation value; (3) Perform contact resistance tests on the battery wafers with an attenuation value > 15%. Determine the acid corrosion resistance of the front and back sides of the battery wafer through the resistance. If the contact resistance of the front side of the battery wafer > 3 ohm, it is determined that the paste on the front side is not acid corrosion resistant. If the contact resistance of the back side of the battery wafer > 2 ohm, it is determined that the paste on the back side is not acid corrosion resistant.

[0007] Preferably, in the test method for detecting the acid resistance of double-sided battery wafers, the concentration of the acetic acid solution in step (1) is 0.6%.

[0008] Preferably, in the test method for detecting the acid resistance of double-sided battery wafers, the temperature of the constant temperature device in step (1) is controlled at 60 - 85°C.

[0009] Preferably, in the test method for detecting the acid resistance of double-sided solar cells, wherein: the contact resistance test of the solar cells with a decay value > 15% in step (3) is specifically as follows:

[0010] Cut the solar cell into strip-shaped pieces, place the strip-shaped pieces on the platform of the contact resistance tester, adjust the position of the probe on the tester to ensure that each probe presses on the sub-grid line of the strip-shaped piece, and perform the contact resistance test.

[0011] Preferably, in the test method for detecting the acid resistance of double-sided solar cells, wherein: the width W of the strip-shaped piece < the distance between the main grid and the auxiliary line; for the strip-shaped piece without the auxiliary line, the width W < the distance between two main grids, 6 × the sub-grid pitch < the length L of the strip-shaped piece ≤ the length of the cell frame; 0.903 mm ≤ the sub-grid pitch ≤ 2.286 mm.

[0012] The advantages of the present invention are as follows:

[0013] In the test method for detecting the acid resistance of double-sided solar cells of the invention, the double-sided solar cell is tested by acetic acid, and it can only determine whether the cell is acid-resistant, but cannot determine which side has problems. By performing the contact resistance test on the solar cells with a large decay value after the acetic acid test, by testing the magnitude of the contact resistance of the front and back sides, it can be determined which side has a large contact resistance, and then which side is more affected by acetic acid corrosion, shortening the detection time at the battery end, and through the contact resistance test, confirming which side of the double-sided solar cell has problems, so as to carry out targeted improvement. Description of the Drawings

[0014] Figure 1 It is the EL test comparison diagram of the embodiment of the present invention.

[0015] Figure 2 It is the attenuation trend diagram of various electrical properties of the embodiment of the present invention.

[0016] Figure 3 It is the cutting diagram of the strip-shaped piece of the present invention. Detailed Embodiments

[0017] The present invention will be further described below in conjunction with specific embodiments.

[0018] Embodiment

[0019] EVA backsheet will produce acetic acid after being eroded by moisture for a long time. In the experiment, a 0.6% concentration acetic acid solution is used to simulate the situation of the module in a humid environment.

[0020] (1) Perform EL image and electrical performance tests on the solar cells, then place the solar cells in a container containing a 0.6% concentration acetic acid solution, place a hollow partition on the solution, place the flower basket carrying the solar cells on the partition, and seal the container containing the solar cells and the acetic acid solution and put it into a constant temperature container, with the temperature set at 85°C;

[0021] (2) Take out the solar cells placed for different times and test their EL images, and compare them with the EL before acetic acid test. For example, Figure 1 , and test the electrical performance of the solar cells with no abnormal appearance in the EL images. Then compare the electrical performance of the solar cells with that in step (1) and calculate the attenuation value;

[0022] Figure 1 For the solar cells corroded by acetic acid in , there is no obvious abnormality in appearance, but from the EL images, the darker the EL edge of the solar cells becomes with the longer acetic acid test time, and the acetic acid mist first corrodes the edge of the solar cells.

[0023] The test results of the electrical performance of the solar cells are shown in Table 1. It can be seen from Table 1 that the longer the acid corrosion time, the less acid corrosion resistant the solar cells are; the attenuation of each electrical performance of the solar cells is as Figure 2 , from Figure 2 it can be seen that the acetic acid test mainly affects the series resistance Rs, fill factor FF and conversion efficiency Ncell. The trend of the conversion efficiency Ncell is opposite to that of the series resistance Rs. Therefore, the attenuation of the test efficiency by acetic acid can be indirectly characterized by testing the series resistance Rs.

[0024] Table 1

[0025] Acetic acid test time 18H 24H 30H Range 0.24％ 0.54％ 1.88％ Mean 0.33％ 0.54％ 1.63％ Variance 1.10E-06 4.50E-06 4.77E-05 Standard deviation 0.00105 0.00212101 0.0069038

[0026] (3) Conduct contact resistance tests on the solar cells with attenuation value > 15%. Determine which side of the solar cell has a larger contact resistance through the resistance, so as to judge the acid corrosion resistance of the front and back sides of the solar cell. If the front contact resistance > 3 ohm, it is determined that the paste on this side is not acid corrosion resistant; if the back contact resistance > 2 ohm, it is determined that the paste on this side is not acid corrosion resistant.

[0027] Cut the solar cells into strip-shaped pieces, place the strip-shaped pieces on the platform of the contact resistance tester, and adjust the position of the probes on the tester to ensure that each probe presses on the sub-grid lines of the strip-shaped pieces for contact resistance testing; there should only be sub-grid lines on the strip-shaped pieces to be tested for contact resistance, and no auxiliary lines or main grid lines, that is, the pattern cannot form a loop)

[0028] The width W of the strip-shaped piece < the distance between the main grid and the auxiliary line. For the strip-shaped piece without auxiliary line, the width W < the distance between two main grids, 6 × the sub-grid spacing < the length L of the strip-shaped piece ≤ the frame length; 0.903 mm ≤ the sub-grid spacing ≤ 2.286 mm.

[0029] According to the EL images, divide the EL blackened area and the normal area of the solar cells according to Figure 3Cut it into strips. Place the strip-shaped parts on the platform of the contact resistance tester, and adjust the position of the probes on the tester to ensure that each probe presses on the strip-shaped secondary grid lines. For patterns with different secondary grid spacings, probe rows with different spacings need to be used for testing. Determine the acid resistance of the bifacial cell based on the measured values of the front and back contact resistances. The side with a larger contact resistance has poorer acid resistance. The test results are shown in Table 2.

[0030] Table 2

[0031]

[0032] From Table 2, it can be seen that the EL blackening area corresponds to a larger front contact resistance, that is, the front has poorer acid resistance.

[0033] Finally, it should be noted that the above specific implementation manners are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A test method for detecting the acid resistance of double-sided solar cells, characterized in that: It includes the following steps: (1) Perform EL image and electrical performance tests on the solar cells. Place a partition in a container filled with acetic acid solution, and place the solar cells after testing the EL image and electrical performance on the partition. Then seal the container and place it in a constant temperature device; (2) Group the solar cells according to the placement time. Take out the solar cells placed for different times and test the EL image, and compare it with the EL image in step (1). Test the electrical performance of the solar cells with no abnormal appearance after EL image comparison. Then compare the electrical performance of the solar cells with the electrical performance in step (1) and calculate the attenuation value; (3) Perform contact resistance tests on the solar cells with an attenuation value > 15%. Judge the acid corrosion resistance of the front and back sides of the solar cells through the resistance. If the front contact resistance of the solar cell > 3 ohm, it is determined that the front paste is not acid corrosion resistant. If the back contact resistance of the solar cell > 2 ohm, it is determined that the back paste is not acid corrosion resistant; The contact resistance test of the solar cells with an attenuation value > 15% in step (3) is specifically: Cut the solar cells into strip-shaped pieces, place the strip-shaped pieces on the platform of the contact resistance tester, adjust the position of the probes on the tester to ensure that each probe presses on the sub-grid line of the strip-shaped piece, and perform the contact resistance test.

2. The test method for detecting the acid resistance of double-sided solar cells according to claim 1, characterized in that: The concentration of the acetic acid solution in step (1) is 0.6%.

3. The test method for detecting the acid resistance of double-sided solar cells according to claim 1, characterized in that: Control the temperature of the constant temperature device in step (1) to be 60 - 85 °C.

4. The test method for detecting the acid resistance of double-sided solar cells according to claim 1, characterized in that: The width W of the strip-shaped piece < the distance between the main grid and the auxiliary line. For the strip-shaped piece without the auxiliary line, the width W < the distance between two main grids, 6 × the sub-grid distance < the length L of the strip-shaped piece ≤ the length of the cell frame; 0.903 mm ≤ the sub-grid distance ≤ 2.286 mm.

Images