A simple approach to extract the unknown parameters of PV modules

Abstract

A simple and accurate technique to compute essential parameters needed for electrical characterization ofphotovoltaic (PV) modules is proposed. A single-diode model of PV modules, including those with series and shuntresistances, is considered accurate and simple. However, PV module datasheets provided by manufacturers providecurrent{voltage (I-V) characteristics as well as the values of selected parameters at standard test conditions (STC), i.e.solar radiation of 1000 W/m2, air temperature of 25◦C, and air mass AM = 1.5. Consequently, important parameterssuch as series resistance (Rs), shunt resistance (Rsh), photocurrent (Iph), and diode reverse-saturation current (Io)are not provided by most manufacturers. Since these parameters are crucial for PV module characterization, our studypresents an exact, closed-form expression forRsthat is solvable numerically while increasing the value of the idealityfactor (a) in small increments, so that four equations are formulated to compute the unknown parameters. To validatethe proposed approach, a set ofIVcurves were computed for different values ofa, and these results were comparedalongside corresponding reference data for the BP SX150 and MSX60 PV modules. Average RMS errors of 0.035 for BPSX150 and 0.014 for MSX60 between the reference data and the computed data suggest that proposed approach couldbe used as an alternative method to quantify important missing parameters required for characterization of PV modules.