Parasitic resistance calculation of PV module at various irradiance based on three condition Lambert-W

Abstract

Serial and parallel parasitic resistances of the photovoltaic (PV) module are needed to determine the characteristics and performance of the module. Its values are constant for a long period operation. Characterization of PV modules using direct irradiation of sunlight is rather difficult to obtain constant radiation under a clear sky condition and the measurement should be taken in a short time period less than 5 minutes. In this work, Rs and Rsh values were determined by characterizing PV module at various levels of sunlight intensity and modeled after Lambert-W function. A Solarland SLP100S-12 monocrystalline 100Wp photovoltaic module was illuminated at different intensity 100%, 75%, 50%, and 25 % using filters covered the PV module surface. Based on the measured I-U curves, three important parameters are generated for the Lambert-W calculation: short-circuit current (Isc), open-circuit voltage (Uoc), and also the current-voltage at the Maximum Power Point (Imp, Ump). The calculated values were 0.63Q + 0.027 for Rs and 93.2Q + 0.588 for Rsh and relative constant for filter variation which are not influenced by the intensity of the sun.