Models of PV Arrays under Non¿¿¿homogeneous Conditions

This chapter presents an approach that can be implemented in any simulation environment, including power???electronics simulation software such as PSIM, in which the user can take advantage of the functional blocks or the definition of new devices through a dynamic linked library. This approach gives a clear advantage, especially in terms of simulation time, over the photovoltaic (PV) models that are already embedded in many commercial software packages and simulation environments. The calculation of the whole current???voltage (I???V) curve of a given string of an assigned set of PV modules subject to a number of different irradiance levels is illustrated. The approach proposed by Petrone and Ramos???Paja aims at calculating the inflection points occurring in the I???V curve when the PV string is subjected to mismatching phenomena. The inflection point appears at each voltage value where at least one bypass diode in the string changes its status.