INTERNAL SERIES RESISTANCE DETERMINATED OF ONLY ONE IV-CURVE UNDER ILLUMINATION

ABSTRACT: For the measurement of the internal series resistance (which desribes internal losses and losses due to bad contacts as well) two IV-curves of different irradiance but of the same spectrum and at the same temperature are necessary according to IEC 60891. For single cells and single modules the second IV-curve can be obtained by covering the cell or module with an insect-screen. For large PV-generators (several kW) this method could not be applied. A new method will be presented which allows to determinate the internal series resistance out of only one IV-curve under illumination. With a new method for the simulation of the second IV-curve, using the effective solar cell equation-method, now it is possible to obtain the internal series resistance out of only one IV-curve measured under illumination. The method will be presented as well as some experimental results to show the accuracy of the method.