Performance estimation of photovoltaic module under partial shading based on explicit analytical model

Abstract

The conventional approach to modeling a typical photovoltaic (PV) module under partial shading conditions is based on the equivalent circuit model, which provides the current–voltage (I–V) relationship in an implicit form. In this study, a novel method based on an explicit analytical model is proposed for estimating the performance of a PV module under partial shading conditions. An explicit expression of voltage in terms of current is derived from the implicit I–V expression of the single-diode model for a single PV cell under different environmental conditions. The model is then extrapolated to a submodule under partial shading conditions, and finally, to a PV module. Using the proposed method, the I–V curve and maximum power of a PV module are calculated analytically and accurately under different partial shading conditions. Owing to the explicitness of the proposed method, the computational complexity and time required are significantly less than Newton’s method and Lambert W function method with similar accuracy. The proposed method is verified via outdoor experiments under different partial shading conditions. The results show satisfactory agreement between the estimated and measured I–V curves and between the P–V curves and the maximum power. The proposed method is accurate and particularly effective for determining the actual performance of PV modules under partial shading conditions, and is thus scalable for direct online applications.