阿特斯&协鑫-晶硅电池LeTID衰减测试方法v6

Measurement of light and elevated temperature induced degradation LeTID of crystalline Si photovoltaic solar cells 2018.10.25 Participants NO. Company/Institute Participants 1 GCL System IntegrationTechnology Co., LTD Sheng Jian, Wang Wei, Wu Yanrong 2 Canadian Solar Inc. Jiang Fangdan, Zhang Daqi, Guo Suqin 3 Gsolar Power Co., Ltd Zhang Hexian 1. Background of LeTID 2. Alternative methods for LID/LeTID 3. Proposal for measurement of cell LeTID 4. Plan of next step Klaus Ramspeck et. al., “Light induced degradation of rear passivated mc-Si solar cells”, in the proceeding of 27th EUPVSEC 1. Background of LeTID ➢ mc-Si PERC solar cells exhibited a big light induced degradation at 75 ℃ ➢ The degradation does not take place at room temperature during illumination, but observed at a temperature of at least 50℃ The defects caused LeTID is neither BO complex nor FeB complex. Remain unknown yet. 1. Background of LeTID Klaus Ramspeck et. al., “Light induced degradation of rear passivated mc-Si solar cells”, in the proceeding of 27th EUPVSEC 1. Background of LeTID 2. Alternative methods for LID/LeTID 3. Proposal for measurement of cell LeTID 4. Plan of next step 2. Alternative methods for cell LID/LeTID measurement Standard Sample Method Procedures Conditions IEC 61215-1 ED2 Modules 2-step 1st step MQT 19.1 Initial stabilization, light soaking 2nd step MQT 23.1 LeTID degradation, current injection 1st step 1 sun, 5 2. Alternative methods for cell LID/LeTID measurement Module LeTID test in IEC 61215-1 ED2 1-step measurement ✓ Detection of mixed LID and LeTID ✓ How to define LeTID ✓ Difference between LID and LeTID 2-step measurement ✓ Compatible with module LeTID measurement IEC 61215-1 ED2 ✓ Get separate LID and LeTID data 2-step measurement preferred. Considerations 1-step or 2-step LeTID Light and Elevated Temperature Induced Degradation is a misleading terminology proposed by Hanwha Q-cells. Fundamental principle The LID and LeTID degradation is caused by defects formation during excess minority carrier injection, either by light soaking or current injection. Light soaking ✓ More relevant to module’s outdoor operation in practice ✓ Suitable for all kinds of crystalline solar cells ✓ Last for long time to feedback results but easy to control and measure Current injection ✓ Compatible with module LeTID measurement IEC 61215-1 ED2 ✓ Precise temperature control, large volume, rapid feedback, small footprint Both light soaking and current injection can be used. Considerations light soaking or current injection LeTID test conditions injection intensity, temperature, time During the excess minority carrier injection at certain temperature, the degradation process and regeneration process happen simultaneously. Either higher injection intensity or higher temperature will speed up both the degradation and regeneration processes. In order to expose the maximum degradation risk, it is essential to choose proper conditions to exhibit degradation process and inhibit regeneration process. Typically, the degradation process dominates at low injection intensity and low temperature. However, certain degradation modes will not exhibit at low temperature, resulting in underestimation of degradation risk. This is why LeTID was brought up. Considerations LeTID test conditions CID test results on multi-PERC cells Dependence of degradation rate on test conditions injection intensity, temperature Considerations LeTID test conditions CID test results on mono-PERC cells LeTID test results of mono-PERC cells are more sensitive to injection intensity than multi-PERC cells. CID test is better than light soaking in exposing degradation risk of mono-PERC cells. Considerations LeTID test conditions 1. Background of LeTID 2. Alternative methods for LID/LeTID 3. Proposal for measurement of cell LeTID 4. Plan of next step 3. Proposal for measurement of cell LeTID At least 20 pcs of cells Procedure a I-V measurement b 1st step light soaking for 20kWh/m2 at 45℃ c I-V measurement d calculate LID by difference in efficiency between a c e Light soaking for 10kWh/m2 at 805℃ f I-V measurement g Light exposure for another 5kWh/m2 in conditions of e h I-V measurement i Repeat g h till stabilized or reach 20kWh/m2 termination criteria j Calculate LeTID difference in efficiency between c i Option 1 Light Soaking IV measurement Light exposure 10kWh/m280 5℃ IV measurement Light exposure 5kWh/m280 5℃ IV measurement Stable or 20kWh/m2 N Y End Light exposure 20kWh/m245℃ IV measurement 1st step 2nd step Procedure a I-V measurement b 1st step light soaking for 20kWh/m2 at 45℃ c I-V measurement d calculate LID by difference in efficiency between a c e 2nd step current injection Isc - Impp, 85℃ , 12 hours f I-V measurement g Current injection for another 12 hours in conditions of e h I-V measurement i Repeat g h till stabilized or reach 96 hours termination criteria j Calculate LeTID difference in efficiency between c i Option 2 Current Injection I-V measurement Current injection Isc-Impp, 85℃ , 12 hours At least 20pcs of cells I-V measurement Current injection Isc-Impp, 85℃ , 12 hours I-V measurement Stabilized or 96 hours Yes End Light soaking 20kWh/m2 45℃ No 1st step 2nd step Termination criteria I-V measurement 3. Proposal for measurement of cell LeTID Report should include at least Test information Date, name, tool, et al. Sample information Number of cells, type, manufacturer, sampling criteria, et al. Test conditions 1st step LID condition, 2nd step LeTID condition, et al. Test results LID rate, LeTID rate, whether stabilized during 2nd step, et al. 3. Proposal for measurement of cell LeTID 1. Background of LeTID 2. Alternative methods for LID/LeTID 3. Proposal for measurement of cell LeTID 4. Plan of next step 4. Plan of next step Feedback from Busan IEC TC82 WG8 meeting - Agree to pass NP - Agree on 2-step measurement - Suggest to collect data on equivalent between light soaking and current injection - Suggest to collect more data to determine LeTID test conditions Next step - To form Project Team - To write draft NP before end of 2018 Thanks QA