9 Botest Systems GmbH-Maurice Lion

Botest Systems GmbH High Speed Solar Cell Testing At Cycle Times of 1000ms and Less 04.06.2019 Maurice Lion Page 217.06.2019 High Speed SC Testing ◼ solar cells have matured ◼ low production cost ◼ efficient use of equipment → high throughput with cycle times of 1s Page 317.06.2019 High Speed SC Testing ◼ solar cells have matured ◼ low production cost ◼ efficient use of equipment → high throughput with cycle times of 1s ◼ solar cell tester ◼ together with sorting last step of production line ◼ Xe Flashers ◼traditionally with 2s cycle time ◼Illumination ◼ charging and lamp driving electronics ◼ flash lamp unit ◼ light guidance ◼measurement electronics ◼ cell driving and IV measurement ◼ additional EL, hot spot, grid resistance Page 417.06.2019 Illumination Requirements ◼ state-of-the-art ◼ homogeneity ◼ spectrum ◼ temporal stability ◼ low angle of incidence desirable → minimize shadowing due to contacting multi bus bar cells etc. ◼ possibility to integrate secondary measurements, e.g. ◼ electroluminescence camera angle ◼ hot spot camera angle ◼ temperature sensors from top → sufficient distance flash lamp unit to solar cell Page 517.06.2019 Illumination Electronics ◼ Charging of capacitors ◼ faster ◼ higher efficiency → ready for next flash in time ◼ Lamp driving ◼ higher average current Page 617.06.2019 Illumination Light Guidance ◼ system design either for light tunnel or for no light tunnel ◼ with light tunnel ◼ reflection on walls even for tunnel with black walls 20 easily possible ◼ good → more light at cell level ◼ bad → high angle of incidence → difficult to access → volume inside tunnel heats up Page 717.06.2019 Illumination Light Guidance ◼ system design either for light tunnel or for no light tunnel ◼ with light tunnel ◼ reflection on walls even for tunnel with black walls 20 easily possible ◼ good → more light at cell level ◼ bad → high angle of incidence → difficult to access → volume inside tunnel heats up → no light tunnel is desired solution ◼ loss in irradiance level at cell to be compensated Page 817.06.2019 Illumination Flash Unit - Efficiency ◼ maximum utilization of light output → reduced requirements on electronics → increased lamp lifetime ◼ minimize absorbing elements ◼ reflectors only ◼ parabolic reflector behind lamp ◼reflected light parallelized Page 917.06.2019 Illumination Flash Unit - Efficiency ◼ maximum utilization of light output → reduced requirements on electronics → increased lamp lifetime ◼ minimize absorbing elements ◼ reflectors only ◼ parabolic reflector behind lamp ◼reflected light parallelized ◼direct light not parallelized Page 1017.06.2019 Illumination Flash Unit - Efficiency ◼ maximum utilization of light output → reduced requirements on electronics → increased lamp lifetime ◼ minimize absorbing elements ◼ reflectors only ◼ parabolic reflector behind lamp ◼reflected light parallelized ◼direct light not parallelized ◼mixture, average angle of incidence reduced → with unchanged driving parameters nearly doubled irradiance Page 1117.06.2019 Illumination LED Flash Unit ◼ Xe Flash unit works for 1000ms ◼ proven and well-known technology ◼ advanced engineering for shorter cycle times ◼ possible switch to LED flash unit ◼ relatively new technology in cell testing ◼ LEDs are mature technology ◼ short cycle times 100ms ◼ times 100ms challenging for high speed flashers ◼ 0V to open open circuit voltage ◼ efficiency too low, even lower with shorter pulse time Page 1217.06.2019 Measurement of HJT cells Hysteresis ◼ HJT and other high efficiency cells ◼ accurate value requires very long flash times 100ms ◼ times 100ms challenging for high speed flashers ◼ 0V to open open circuit voltage ◼ efficiency too low, even lower with shorter pulse time ◼ open circuit voltage to 0V ◼ efficiency too high, even higher with shorter pulse time Page 1317.06.2019 Measurement of HJT cells Hysteresis ◼ HJT and other high efficiency cells ◼ accurate value requires very long flash times 100ms ◼ times 100ms challenging for high speed flashers ◼ 0V to open open circuit voltage ◼ efficiency too low, even lower with shorter pulse time ◼ open circuit voltage to 0V ◼ efficiency too high, even higher with shorter pulse time ◼ hysteresis calculation ◼ between both curves but not mean value ◼ stable value even below 20ms flash time → measurement of high efficiency cells with low cycle time Page 1417.06.2019 Page 1517.06.2019 Software ◼ with lower cycle time even short delays become important ◼ user interface design providing all relevant information ◼ module spanning view and control ◼ e.g. calibration and verification ◼relatively complex interaction cell transport system ↔ tester ◼extended software interface for complete control from single system and simplified, reproducible handling Page 1617.06.2019 Botest Systems GmbH Unterwittbacher Strae 28 97892 Kreuzwertheim GERMANY www.botest.com Maurice Lion Phone 49 9342 93551-0 Fax 49 9342 93551-19 Email infobotest.com