硼镓共掺高效多晶PERC电池的光衰研究-孙菁-阿特斯.pdf

Canadian Solar Inc. System technology center, Jing Sun, October 2018 CSIQ NASDAQ Listed LeTID PERFORMANCE RESEARCH OF MULTI-PERC MODULE 2 CSI P4 LeTID introduction01 LeTID vs LID results02 Conclusion Discussion04 LeTID vs Dark annealing + LID results03 3 Front Rear • State of the art MCCE (Metal Catalyzed Chemical Etching) • PERC structure using ALD Al2 O3 passivation • 5 busbar design / MBB multi-busbar (9) • Controlled LID/LeTiD • Excellent low light response • Lower temperature coefficient • Enables Bifacial cells Main Characteristics CSI P4 introduction – Poly PERC technology 4 CSI P4 introduction - Higher output power • P4 has higher output power than standard mono • P4 Ku module wattage is comparable to mono PERC 6K-P4 3K-P4 + MBB 0% 10% 20% 30% 40% Poly• Similar findings from UNSW 9 Proposed LeTID Mechanism – UNSW • LeTID defect is hydrogen activated. The amount of H released during firing has correlated to degradation extent. • Defects is more apparent in PERC and high efficiency structures as H concentrations increase and these structures are more sensitive to degradation. • Innovative hydrogen charge state control has large impact on both diffusivity reactivity of H in silicon. 10 Proposed LeTID Mechanism – Bredemeier et al. MiX complex After high firing temperature Metal precipitates Mi impurities Cooling Phase Temperature + Light MiX* recombination centers (fast degradation) Temperature + Light (long time) Metal crystal defects (regeneration) 11 CSI P4 LeTID introduction01 LeTID vs LID results02 Conclusion Discussion04 LeTID vs Dark annealing + LID results03 12 98.38% 97.58% 98.47% 98.07% 95% 96% 97% 98% 99% 100% 101% 102% 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 • Initial fast degradation, followed by slow degradation. • After thousands of hours, power degradation stabilizes, below 2%. • No recovery observed through all the testing period. LeTID vs LID results – Power degradation analysis CSI COMP#1 COMP#2 Control 99.73% 98.70% 98.25% 98.06% Relativ e Pm ax LeTID LID LeTID test conditions (IEC61215 draft): 75°C, (Isc-Impp) current 162h+162h x N N cycles, ΔPmpp1% 13 Initial After LeTID Initial LID After LID • EL image after LeTID showing no significant changes through the complete testing period LeTID vs LID results – EL images analysis LeTID LID 14 S T C P e r f o r m an ce T es t 1st cy cl e Li g ht soa k ( 60 k W h / m 2 ) 2nd cy cl e Li g ht soa k ( 60 k W h / m 2 ) S T C P e r f o r m an ce T es t 3th cy cl e Li g ht soa k ( 60 k W h / m 2 ) S T C P e r f o r m an ce T es t 4 th cy cl e Li g ht soa k ( 60 k W h / m 2 ) S T C P e r f o r m an ce T es t S T C P e r f o r m an ce T es t 5th cy cl e Li g ht soa k ( 60 k W h / m 2 ) S T C P e r f o r m an ce T es t LeTID vs LID results – Long term outdoor exposure 3rd party data • IEC61215:2016 LID testing at TUV SUD, long term average degradation rates 1.2%. Test flowchart Accumulative light soak (kWh/m2) Pma x degra da tio n (%) CS3U-350PB-FG P4 15 CSI P4 LeTID introduction01 LeTID vs LID results02 Conclusion Discussion04 LeTID vs Dark annealing/LID results03 16 Dark annealing + LID test procedure (UNSW) Dark annealing treatment: Accelerated by 150 °C dark anneal for 10 hours prior to LID. Dark annealing (150 °C) LID (1000W/m2, ~70 °C) 17 95% 96% 97% 98% 99% 100% 101% 0 100 200 300 400 500 600 95% 96% 97% 98% 99% 100% 101% 0 10 20 30 40 50 60 70 80 LeTID LeTID vs dark annealing + LID results – Power degradation analysis • Power degradation of P4 PERC module after process optimization Non-optimized process. • LeTID 400h = dark annealing + LID72kwh/m2 Dark annealing + LID Test time (h) Test time (h) Rel at ive Pm ax Optimized process Control module Non-optimized process 18 Initial After dark annealing After dark annealing + LID LeTID vs dark annealing + LID results – EL images analysis • EL image of Dark annealing + LID does not show any cell patchwork for P4 PERC modules after process optimization. 19 CSI P4 LeTID introduction01 LeTID vs LID results02 Conclusion Discussion04 LeTID vs Dark annealing + LID results03 20 Conclusions  CSI applies state-of-the-art processes to mitigate LID and LeTID in POLY PERC cells, including patented, unique CSI process steps  CSI has extensive and documented control points during production to ensure homogeneity in the reliability results  CSI collaborates with research institutes (included UNSW) to stay at the head of innovations in the field of PERC technology  No significant degradation observed for CSI P4 modules with any of the industry recognized LeTID test protocols: IEC61215 draft method (CID), UNSW (dark annealing + LID).  Good correlation between long term outdoor exposure and laboratory test data. 21 22 LeTID – Dark annealing as an accelerated preconditioning Dark annealing can accelerate the evolution of the Type 1 defect degradation • Each identical sister mc-Si PERC cells dark annealed at a different temperature for 2.5 hours, then light soaked at standard 75 °C 1kWh/m2. • Dark annealing first accelerates type 1 defect forming and recovering. • Eventually, the dark annealing eliminates the type 1 defect, and only the type 2 defect remains.