A novel technique to extract the maximum power of photovoltaic array in partial shading conditions

Abstract

Photovoltaic (PV) arrays are composed of PV cells which have a nonlinear power-voltage characteristic. To extract maximum amount of energy from a PV array, it is essential to track maximum power point (MPP). When all PV cells are subject to the same solar energy, MPP is found easily. However, in some ambient conditions, PV cells are partially or completely shadowed. Under partial shading conditions (PSCs), overall power-voltage curve will have several peaks. This paper presents a novel approach for MPP tracking, utilizing configuration of PV cells in series and parallel that may deliver maximum power in shading conditions. As such, instead of blindly searching for the global MPP among local MPPs, the proposed method limits the search space by calculating the required combination of series and parallel PV cells that can deliver global MPP. This efficient technique leads to a faster dynamic response when partial shadowing is encountered, while maintaining the conventional MPP tracking in normal condition. Moreover, the method does not require any additional hardware. Rather, the existing MPP tracking algorithm should be modified to accommodate PSCs. The efficiency of proposed technique is investigated via time-domain studies, where results verify the superiority of proposed method compared to other approaches.