A testing method for a copper grid solar cell

Abstract

The present invention discloses a testing method for copper grid solar cells, and the method is as follows: Clamp the battery to be tested with a conventional NBB solar cell test probe row tooling, perform irradiation testing under simulated standard solar conditions, and extract the I-V electrical data of the solar cell; Set a test quantity constant C. When the number of continuously tested copper grid batteries reaches the set test quantity constant C, use a set of monitoring battery wafers with calibrated data to verify the test stability; If the deviation of the verification value of the monitoring battery wafer from the original calibrated value is greater than the control test error requirement, feedback an alarm message, execute the probe tin adhesion cleaning step, and after completion, continue with mass production testing and clear the test quantity count; If the deviation of the verification value of the monitoring battery wafer from the original calibrated value is within the control test error requirement, then continue with mass production testing and clear the test quantity count. The present invention can significantly reduce the tin adhesion problem on the surface of the copper grid battery test probe, reduce the test error, and improve the testing accuracy of solar cells.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly to a testing method for copper grid solar cells. Background Art

[0002] Photovoltaic solar energy, as a clean and renewable energy source, has always been a concern for people. Copper grid solar cells have gradually emerged in the market because the cost of their electrodes is significantly lower than that of the current mainstream silver paste electrodes. The manufacturing process of copper grid cells requires a tin coating to be covered on the surface of the copper electrode to reduce the oxidation of the copper electrode. Due to the soft texture of the surface tin layer, it is easy to adhere to the test probe during the battery IV test process. As the number of tests increases, the contact resistance between the probe and the main grid line electrode of the battery increases sharply, seriously affecting the accuracy of the battery IV curve test.

[0003] Currently, the mainstream photovoltaic cell IV testing method is applied to silver paste cells, without considering the influence of adhesion on the test probe surface and the problem of monitoring the stability during the test process. There are no special requirements for the probe tip type. However, if it is directly applied to the test of copper grid cells, there will be obvious tin adhesion problems on the test probe, and the contact resistance between the probe and the main grid will increase significantly, seriously affecting the consistency and accuracy of the battery IV test.

[0004] The electrode of the copper grid cell is composed of a conductive copper grid at the bottom and an extremely thin anti-oxidation tin coating on the surface of the copper grid line. The tin coating has a soft texture. During the conventional probe test process, the tin coating is easily adhered to the contact surface between the probe and the battery. As the number of tests increases, the tin adhesion problem becomes significantly more serious, resulting in a sharp increase in the contact resistance between the probe and the battery chip, thus significantly affecting the accuracy of the battery IV curve test. Summary of the Invention

[0005] In view of the above problems, the present invention provides a testing method for copper grid solar cells that can significantly reduce the tin adhesion problem on the surface of the test probe of copper grid cells, reduce test errors, and improve the testing accuracy of solar cells.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a testing method for copper grid solar cells, the method comprising the following steps:

[0007] Clamp the battery to be tested with a conventional NBB solar cell test probe row tooling, and perform irradiation test under simulated standard solar conditions to extract the I-V electrical data of the solar cell;

[0008] Set a test quantity constant C. When the number of continuously tested copper grid cells reaches the set test quantity constant C, use a set of monitoring cell sheets with calibrated data to verify the test stability;

[0009] If the deviation between the verification value of the monitored solar cell and the original calibration value is greater than the control test error requirement, an alarm message is fed back, the probe tin adhesion cleaning step is executed, and after completion, the mass production test operation is continued and the test quantity count is cleared;

[0010] If the deviation between the verification value of the monitored solar cell and the original calibration value is within the control test error requirement, the mass production test operation is continued and the test quantity count is cleared.

[0011] Furthermore, the test probe row tooling needs to be used in combination with test probes with sharp head shapes that have a self-cleaning effect. The probe head penetrates the tin oxide anti-oxidation coating on the surface of the copper grid battery electrode and directly contacts the underlying copper grid line of the electrode, which can significantly reduce the contact resistance between the probe and the battery surface electrode, thereby slowing down the influence of tin adhesion.

[0012] Furthermore, the range of the test quantity constant C is 5000 - 50000.

[0013] Furthermore, for the verification test stability, a monitored solar cell with a set of calibration data is used, and the IV monitoring items are selected from one or a combination of fill factor FF, conversion efficiency Eta, and series resistance Rs.

[0014] Furthermore, for the probe tin adhesion cleaning step, a fine grinding block made of EVA material with a surface roughness greater than 10000 mesh is used for micro-grinding. The fine grinding block can achieve the purpose of removing tin adhesion on the probe surface without causing excessive damage to the original coating on the probe surface.

[0015] From the above description of the structure of the present invention, compared with the prior art, the present invention has the following advantages:

[0016] Compared with the existing solar cell I-V test technology, the present invention can significantly reduce the problem of tin adhesion on the surface of the test probe of the copper grid battery, reduce the error of the solar cell I-V test, and improve the accuracy of the solar cell test; at the same time, this test method can significantly eliminate the influence of the surface protective film of the electrode, be compatible with the testing of solar cells with different electrode materials such as copper grid, silver paste, and aluminum paste, and the test results are stable and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0018] Figure 1 It is a schematic diagram of the test flow for one test cycle of an embodiment of the present invention;

[0019] Figure 2Schematic diagram of the contact situation between the test probe and the battery electrode in the embodiment of the present invention;

[0020] Figure 3 It is a comparative chart of the tracking tests of the same group of batteries with the same efficiency by the traditional test technology and the technical solution of the present invention in the embodiment of the present invention. Detailed implementation manners

[0021] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to 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.

[0022] Embodiment 1

[0023] A testing method for a copper grid solar cell, the method comprising the following steps:

[0024] 1. Clamp the copper grid battery to be tested with a conventional main grid solar cell test probe row tooling, and the test probe row tooling is used in combination with a test probe in the shape of a circular ring needle head with a certain self-cleaning effect. As Figure 2 shown, the probe head 1 penetrates the anti-oxidation tin coating 2 on the surface of the copper grid battery electrode and directly contacts the underlying copper grid line 3 of the electrode, and irradiance treatment is carried out under simulated standard test conditions to extract the I-V electrical data of the solar cell;

[0025] 2. Start the continuous test mode, set a test quantity constant to 5000. When the number of continuously tested copper grid batteries reaches 5000, use a group of 10 calibration data monitoring battery slices to verify the test stability. Take the Eta mean value of this group of monitoring battery slices as the monitoring item, and take that the deviation of the conversion efficiency Eta mean value of the monitoring battery slice from the initial calibration value is greater than 0.05% as the warning signal. The initial calibration conversion efficiency Eta mean value of the monitoring battery slice is 24.00%;

[0026] 3. As Figure 1 shown, when the test quantity reaches the preset test quantity constant 5000, use the monitoring battery slices to verify the stability. If the deviation of the conversion efficiency Eta mean value of the monitoring battery slices reaches the warning signal, perform the probe tin adhesion cleaning action. If the deviation of the Eta mean value of the monitoring battery slices does not reach the warning signal, re-count and continue the test until the test quantity reaches the preset test quantity constant 5000 again; the measured conversion efficiency Eta mean value of the monitoring battery slices is 24.01%, and the deviation from the initial calibration conversion efficiency Eta mean value of 24.00% is only 0.01%, which does not reach the warning signal, so re-count and continue the test to the next test quantity constant 5000;

[0027] 4. Repeat step 3 until the data measured from the monitored cell deviates from the initial calibration value to reach the warning signal. When it is measured that at the fifth time of the test quantity reaching the preset test quantity constant of 5000, the average value of the conversion efficiency Eta of the monitored cell is 23.93%, deviating from the initial calibrated Eta average value by 0.07%, reaching the warning signal, perform the probe tin adhesion cleaning action;

[0028] 5. Use a fine grinding block made of EVA material with a surface roughness greater than 10000 mesh to wipe the contact surface between the probe and the battery electrode. After wiping, clear the test quantity, continue the test and re - count;

[0029] 6. Repeat steps 3, 4, and 5 until all the copper grid batteries to be tested are completely tested.

[0030] Embodiment 2

[0031] A test method for a copper grid solar cell, the method comprising the following steps:

[0032] 1. Clamp the copper grid battery to be tested with a conventional main grid solar cell test probe row tooling. The test probe row tooling is used in combination with test probes in the shape of sharp - claw needles with a certain self - cleaning function. The head of the probe penetrates the anti - oxidation tin coating on the surface of the copper grid battery electrode and directly contacts the underlying copper grid line of the electrode. Under simulated standard test conditions, perform irradiation treatment and extract the I - V electrical data of the solar cell;

[0033] 2. Start the continuous test mode, set a test quantity constant of 10000. When the number of continuously tested copper grid batteries reaches 10000, use a group of 10 calibrated data monitoring cells to verify the test stability. Take the average value of Eta of this group of monitoring cells as the monitoring item, and take the deviation of the average value of the conversion efficiency Eta of the monitoring cells from the initial calibration value being greater than 0.05% as the warning signal. The initial calibrated conversion efficiency Eta average value of the monitoring cells is 24.00%;

[0034] 3. As Figure 1 shown, when the test quantity reaches the preset test quantity constant of 10000, use the monitoring cells to verify the stability. If the deviation of the average value of the conversion efficiency Eta of the monitoring cells reaches the warning signal, perform the probe tin adhesion cleaning action. If the deviation of the average value of Eta of the monitoring cells does not reach the warning signal, re - count and continue the test until the test quantity reaches the preset test quantity constant of 10000 again; it is measured that the average value of the conversion efficiency Eta of the monitoring cells is 23.97%, deviating from the initial calibrated conversion efficiency Eta average value of 24.00% by 0.03%, not reaching the warning signal;

[0035] 4. Re - count, continue the test until the next test volume constant of 10,000. The measured average value of the conversion efficiency Eta of the monitored solar cell is 23.94%, and the measured data deviates from the initial calibration value by 0.06%, reaching the warning signal. Perform the cleaning action for the tin adhesion on the probe.

[0036] 5. Use a fine grinding block made of EVA material with a surface roughness greater than 10,000 mesh to wipe the contact surface between the probe and the battery electrode. After wiping, clear the test quantity and continue the test and re - count.

[0037] 6. Repeat steps 3, 4, and 5 until all the copper - grid batteries to be tested are completely tested.

[0038] Reference Figure 3 , in this Example 1 and Example 2, the test tracking situations of the circular - needle - shaped test probe with a preset test volume constant of 5000 and the 9 - claw - needle - shaped test probe with a preset test volume constant of 10,000 are compared. The monitored data during the test process of the monitored solar cell is shown in Table 1. It can be seen from Table 1 that as the test quantity of the copper - grid battery increases, the deviation of the measured average value of the conversion efficiency Eta of the monitored solar cell from the initial calibration average value shows a slow increase. After performing the cleaning action for the tin adhesion on the probe, the measured average value of the conversion efficiency Eta of the monitored solar cell returns to be equivalent to the initial calibration Eta average value of 24.00%.

[0039] Compared with the existing solar cell I - V test technology, the present invention can significantly reduce the problem of tin adhesion on the surface of the test probe for copper - grid batteries, reduce the error of the solar cell I - V test, and improve the accuracy of the solar cell test. At the same time, this test method can significantly eliminate the influence of the surface protective film of the electrode, be compatible with the tests of solar cells with different electrode materials such as copper - grid, silver - paste, and aluminum - paste, and the test results are stable and reliable.

[0040] Table 1 Comparison data of the electrical performance parameters of the monitored solar cell before and after the electro - injection treatment using the technical solution of the present invention

[0041]

[0042] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A testing method for copper grid solar cells, characterized in that: the method comprises the following steps: clamp the battery to be tested with a conventional NBB solar cell test probe row tooling, perform irradiation test under simulated standard solar conditions, and extract the I-V electrical data of the solar cell; the test probe row tooling needs to be used in combination with sharp-tipped test probes with self-cleaning function, and the probe head penetrates the anti-oxidation tin coating on the surface of the copper grid battery electrode and directly contacts the copper grid line at the bottom layer of the electrode; set a test quantity constant C, and when the number of continuously tested copper grid batteries reaches the set test quantity constant C, use a set of calibration data monitoring battery slices to verify the test stability; if the deviation of the verification value of the monitoring battery slice from the original calibration value is greater than the control test error requirement, feedback an alarm message, execute the probe tin adhesion cleaning link, and after completion, continue the mass production test action and clear the test quantity count; if the deviation of the verification value of the monitoring battery slice from the original calibration value is within the control test error requirement, then continue to execute the mass production test action and clear the test quantity count; the range of the test quantity constant C is 5000-50000.

2. The testing method for a copper grid solar cell according to claim 1, characterized in that: the verification of the test stability uses a set of calibration data monitoring battery slices, and the IV monitoring items are selected from one or a combination of fill factor FF, conversion efficiency Eta, and series resistance Rs.

3. The testing method for a copper grid solar cell according to claim 1, characterized in that: in the probe tin adhesion cleaning link, a fine grinding block made of EVA material with a surface roughness greater than 10000 mesh is used for micro-grinding.

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