Overview the Approaches for Maximum Power Point of Photovoltaic Arrays in partially Shaded Environment*

Due to the partial shade condition,the photovoltaic (PV) array output characteristics are different from normal condition.As shown in this paper,the output P-V characteristic curve will show multiple power peaks and the position of the maximum power point(MPP) appears uncertainly.In this case, the tradition methods such as constant voltage, perturb & observe algorithms, incremental conductance are difficult to accurately track the MPP in partially shaded environment.This paper summarizes and analyzes the research status of maximum power point tracking (MPPT) technology.Then on the base of these, the current literature about MPPT technology are divided into three categories:optimizing the PV array structure,traditional twostage improved algorithm and the intelligent control strategy such as swarm intelligence, artificial neural network technique,fuzzy-MPPT control method.Comparatively, the intelligent algorithms show excellent tracking performance. As the research on MPPT techniques is ongoing work.Finally,the issues that need to be further concerned with MPPT under the shadow condition in the future are discussed.