Minimizing the impact of losses on MPP tracking of PVs under shading conditions

Certain PV system parameters such as residual losses, are either neglected or assumed as trivial when their dynamics are studied. Even though this may be the case in some approaches, it is proven that residual losses heavily influence the system operation, especially when tackling the problem of locating the maximum power point (MPP) under normal and partial shading irradiance conditions. Particularly, analytic formulas pertaining the mentioned losses are derived in this paper and their effect on MPP tracking is investigated. As losses are greatly affected by the current flowing through the respective element, they can be minimized through optimization techniques. However, both, the issue of minimizing the residual losses and that of tracking the operating condition at MPP, is proposed to be combined into a unique optimization problem. It is important that the combined optimization approach is especially efficient in the case when more than one local maximum exist as happens in partial shading irradiance conditions. The whole analysis and the proposed optimization technique is evaluated under normal and adverse irradiation conditions whereas the simulation results totally verify the validity of the method.