Quantitative Study of the Effect of Non-Uniform Irradiance on Module Performance Combining EL and DLIT Imaging with Circuit Modeling

This paper presents a quantitative study of how the non-uniform irradiance from solar simulators and the often overlooked non-uniformities in modules (e.g. mismatched cell performance in a module, connection of cell strings, bypass diodes) affect the measurement accuracy in Si module power calibrations. By implementing spatial non-uniformity maps of solar simulators and experimental diode parameters of individual cells in a module to our circuit model, it enables a better understanding of the interaction of simulator irradiance non-uniformity with module imperfections in module power measurements. The comparison between simulation and experiment shows that with a nonuniform irradiance of 3%, the P
_MAX
deviations could be as low as ~0.5 % for good-quality Si modules, and ~2% for poor-quality Si modules, confirming the sensitivity of module power calibrations to module properties.