Effects of dynamic parameters on measurements of IV curve

In current-voltage characteristic measurements of a PV module, distortions of curves can often be observed when measurements are done under flash tester with different sweeping rates of curve tracing, direction of tracing from short circuit to open circuit (SCOC)or from open circuit to short circuit (OCSC). In our recent work, we observed that dissimilarities of IV curves of a PV module, maximum power and fill factor, can be explained in terms of charging or discharging capacitive current due to voltage dependence of solar cells. This paper describes that measured maximum powers of a PV module are deviated around 2% when measurements are done with varying sweeping rates from 2 ms to 10 ms and directions of tracing of SCOC and OCSC conditions. The results are comparable with time constants of a module obtained by using dynamic characterization. Our methods using square wave inputting signal, both in the dark and in the illumination conditions, can determine not only time constants, but also determine dynamic parameters of a module. We found that the overestimation or underestimation of output powers are obtained when the sweeping rates are not more than time constants, and each time constant is depend on each operating voltage.