An accurate method for parameters determination of current voltage characteristics of photovoltaic modules

Abstract

The solar power conversion capacity and the output performance of photovoltaic devices, depend mainly on the electrical characteristics of the cell, the module or the array. Therefore, knowing precisely the current versus voltage characteristics remains essential to perform the productivity as well as the solar efficiency of these devices. Researchers presented several methods, but the precise determination of the PV cell parameters remains a challenge. In this paper, we describe with rigorous way an analytical and simple method giving directly the expression of the photocurrent, the diode reverse saturation current, the shunt resistance, the series resistance and the ideality factor for a one exponential model. The three points usually used, at short circuit current, the maximum power and at open circuit, give four equations for the determination of unknown parameters. The fifth equation is at the point corresponding to half of the short circuit current. These equations are reduced to two nonlinear equations with two unknown parameters easily solved by the MathCAD software. The test of a polycrystalline Pv module is performed in a laboratory, the numerical values obtained give the best results compared to some previous methods and show a minimal error. A study about temperature effect on the all parameters was also made and shows a good conformity with the theoretical models, which proof the accuracy of the method.