A Modified Approach for Parameter Estimation of Photovoltaic (PV) Module under Varying Climatic Conditions

Abstract

This paper presents the five extracted unknown parameters $(R_{s}, R_{sh}, I_{ph}, I_{sat}$, and $\textit{a})$ of a single diode model under the standard test condition (STC) and analyzes their effect on the performance of PV cell with a realistic data of varying irradiation and temperature. The proposed modified equations are capable of accurately extracting the unknown parameters as well as the values at the three remarkable points for every increase in temperature is also presented. These were all programmed in a Matlab using the iterative Newton-Raphson method. Results of the study are consistent with the experimental I-V and P-V characteristics for the modules under study. Nevertheless, the datasheet of the photovoltaic module provided contains current-voltage characteristics by various manufacturers with all the parameters selected at the standard test condition (STC). Furthermore, this paper ventures to point out that the resistance in series and parallel, vary significantly with variation in temperature and irradiance, and these parameters amongst others determine the durability of PV cells and are very important for the electrical characterization of a photovoltaic module. Hence, the model parameters of any PV cell operates depending on the irradiance intensity level and temperature of the environment, the reliance on the electrical parameters of these cells are discussed under the effect of various temperature and irradiation, at the short-circuit current, open-circuit voltage and maximum power slopes of the I-V curve.