An Improved 0.8 VOC Model Based GMPPT Technique for Module Level Photovoltaic Power Optimizers

Photovoltaic modules may experience some mismatching conditions that affect their available power capacity, causing inefficient maximum power point tracking (MPPT). Furthermore, their power-voltage (P-V) characteristic curve becomes a multi-peak structure in such conditions owing to the presence of bypass diodes included since every part of the modules may receive different solar irradiance. By taking into account these facts, this paper introduces an improved global MPPT technique comprising 0.8 V-OC model and the limited and adaptive scan approach. The proposed technique eliminates the requirement of some threshold value, leading to unreliable operation which the classical 0.8 V-OC model based studies suffer from. Furthermore, the tracking time has been reduced substantially with the proposed technique by limiting scanning interval. Performance of the proposed technique has been verified by experimental studies and compared with classical 0.8 V-OC model and a full scanning technique, which have been already presented in the literature. Experimental results show that the proposed technique is simple to be implemented and it has better performance than classical 0.8 V-OC model, full scanning, and perturb and observe algorithms. Therefore, the proposed technique is feasible and it can be used technically in module level distributed MPPT (DMPPT) applications.