Exact analytical expressions modelling effects of incident irradiance and temperature on physical parameters of photovoltaic solar module

In this paper, we present three methods for extracting physical parameters of single diode electronic circuit modeling a photovoltaic solar module. The physical parameters we are seeking are photocurrent I-ph, saturation current I-s, ideality factor eta, series resistance R-s and shunt conductance G(p). The first approach uses exact solution of the characteristic equation, the second is based on exact expression of dynamic conductance and the third utilizes exact expression of the integral of translated current-voltage characteristics (I-I-sc,). In all these methods, we perform numerical fitting of experimental data of current, dynamic conductance and area under translated characteristics with appropriate mathematical expressions to reach the values of model physical parameters under standard test conditions (STC). We consider these numerical values as initial conditions and use them to derive mathematical expressions describing effects of incident solar irradiance and module temperature on physical parameters, via temperature coefficients available as well as irradiance coefficients extracted from module datasheet. The mathematical expressions derived are tested on Kyocera KC175GT photovoltaic solar module under different conditions of incident irradiance and temperature, good agreement between experimental and predictive characteristics is found.