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

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 (R_s), shunt resistance (R_p), diode ideality factor (a), dark saturation current (I₀) and photo-generated current (I_pv) 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 R_s and R_p 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.