Improvements in methods for analysis of partially shaded PV modules

Abstract

Several methods for analyzing photovoltaic (PV) systems under partial shading conditions (PSC) can be found in the literature. However, the simplest methods are not very accurate. This article presents (1) a simple and accurate method to model I–V curves for PSC and (2) an improvement of a simplified method, without calculating the I–V curves, to accurately estimate the energy generated by PV systems under PSC. The I–V curves of two PV modules under PSC were measured. The measured curves were compared with modeled curves using two methods from the literature and a new proposed method. Four simplified methods from the literature for estimating the energy generated by PV systems were analyzed. The accuracy of these methods was investigated by comparing the calculated values with measured data from a PV system. For modeling the I–V curves, the new method showed a mean absolute percentage error of 1.5% and proved to be accurate. For the evaluated PV system, using a monthly database and the proposed diffuse shading factor resulted in differences between the measured and modeled results of up to 10% per month and 5% for the entire measurement period. The two proposed methods are simple and accurate.