In this paper, the unknown parameters of the photovoltaic (PV)
Keywords: genetic algorithm, photovoltaic, unknown parametersCopyright © 2016 Institute of Advanced Engineering and Science. All rights reserved.
IntroductionThe basic device of a photovoltaic (PV) system is the PV cell. PV cell is a semiconductor diode whose p-n junction is effected by light [1]. Cells may be grouped in series and parallel to form a module. For large power applications, modules are grouped in series and parallel to form an array.Manufacturer datasheets of the PV modules does not give all the required parameters to obtain the current-voltage (I-V) characteristics of the module analytically. These unknown parameters are the module intrinsic series resistance, R s , parallel resistance, R sh , the ideality factor, a, the diode reverse-bias saturation current, I o , and the module photo current, I ph . These parameters were obtained, in many previous studies by minimizing the absolute error between the PV module characteristics datasheet and the mathematical model of the PV module [2][3][4][5][6][7]. This minimizing technique was processed by different methods.Curve fitting method was used to obtain these unknown parameters [2]. This method proposed more sophisticated model using an extra diode (double-exponential model) [3]. The parameters Rs and Rsh were obtained using the iterative solution to minimize the error between the experimental maximum power given in the data sheet and that obtained from the mathematical model [3][4]. The accuracy of this method depends on the proper assumption of Rs and Rsh. The parameters "R s , R sh and a" for the module were obtained by using NewtonRaphson method [5]. The solution obtained from this method depended on the correct assumption of the initial values of the unknown parameters to insure convergence of the solution. A trial and error algorithm was performed to obtain these unknown parameters [6]. In [7][8], the unknown parameters of the PV module were obtained using differential evolution (DE) algorithm. The values for I o , I Ph and R sh are analytically computed while a and R s are computed by using DE.In this paper, the unknown parameters, Rs, Rsh, a, Io and Iph are determined using GA method at standard test condition (STC) [3]. Also, I-V and power-voltage (P-V) characteristics are obtained at various cell temperature and sunlight irradiance conditions. The characteristics obtained from this proposed method are compared with those given in the module datasheet.