A model of photovoltaic fields in mismatching conditions featuring an improved calculation speed

The model of photovoltaic (PV) fields in mismatching conditions presented in this paper is a tradeoff between accuracy and calculation time. The detailed single diode model, including series and parallel resistances, is considered for the PV modules, while the bypass and blocking diodes are represented with a piecewise linear model. The model profits from the possibility to express each PV module voltage as an explicit function of the current by using the Lambert-W function. The balancing of the string voltage with those ones of the active and inactive modules, as well as of the blocking diode, allows to construct only one non-linear equation depending on the string current. Consequently, the solution of only one equation allows to calculate the string current for a given string voltage, and the current of the whole field is calculated by adding the currents of all parallel strings. The advantages of the proposed model are illustrated by comparing it with two approaches recently published in literature. The model accuracy is evaluated with small, medium and large PV fields, and its usefulness for performing energetic analysis and dynamical simulations is also illustrated. Finally, experimental validation of the model on a small scale PV array is provided. (C) 2012 Elsevier B.V. All rights reserved.