I-V-curve analysis using evolutionary algorithms: Hysteresis compensation in fast sun simulator measurements of HJT cells

State-of-the-art solar cell technologies, such as hetero-junction cells or PERC cells, exhibit a time-dependent deformation of their current-voltage characteristics in fast solar simulator measurements. This hysteresis effect is due to an increased internal capacitance. It manifests itself as a pronounced difference between I–V-curves depending on the measurement direction, i.e. Isc→Voc or Voc→Isc. Thus, it leads to an imprecise determination of the cell performance parameters in particular at the maximum power point. In this study, an algorithm-based correction procedure for these capacitance-induced effects is presented. Using evolutionary optimization algorithms, our correction approach allows the determination of a steady-state curve together with the extraction of all cell parameters featured in a time-dependent equivalent circuit model. It can be implemented without any hardware upgrades and applied to measurement times as low as a few milliseconds. As our basic approach is entirely independent of the underlying model, it is applicable to any solar cell technology by adapting the model under consideration.