Voltage loss analysis of CdSeTe solar cells at maximum power point

Much of the research effort in CdSeTe photovoltaics is aimed at improving cell voltage at open-circuit. However, solar cells operate at their maximum power point (mppt), where the breakdown of voltage losses will be different to at open-circuit. We have developed a camera-based PL system that can measure the implied JV curve of CdSeTe solar cells, enabling voltage loss analysis at mppt. An implied JV curve is produced at each pixel, with a resolution of tens of microns. We use the system to map the implied efficiency and implied fill factor across a CdSeTe substrate. JV and suns JV measurements can also be performed in the system, so that the implied JV curves can be compared to actual JV and pseudo JV curves to provide more detailed loss analysis. We use the system to compare the breakdown of voltage losses at mppt to those at open circuit for a >19% efficient CdSeTe cell.