Parameters estimation of photovoltaic module using nonlinear least square algorithm: A comparative study

Abstract

This paper compares different methods for extraction of photovoltaic (PV) module parameters. Nonlinear least-square method based on trust-region algorithm is proposed here to extract five unknown parameters such as series resistance (Rs), shunt resistance (Rp), diode ideality factor (a), dark saturation current (I0) and photo-generated current (Ipv) under standard test conditions (STC) of PV module. Comparative analysis has been drawn between the proposed method and two other popular methods such as Villalva's iterative method and modified Newton-Raphson method. The principle of trust-region algorithm is briefly reviewed. Two parameters Rs and Rp are only extracted by Villalva's iterative method whereas all five unknown parameters can be extracted by the proposed method and by modified Newton-Raphson method. The accuracy of estimated parameters depends on tolerance band and initial conditions. The time of computation for parameter extraction of different methods has been compared.