Minimization of Electrical Losses in Two-Axis Tracking PV Systems

In this paper, approximate analytical expressions for the power duration curve, the optimum inverter size, the annual energy losses in dc and ac cables, the annual energy losses in the step-up transformer, and the optimum transformer size have been derived for photovoltaic plants mounted on two-axis tracking systems in any European location and of any size. The derived analytical expressions contain only a few unknown parameters, which can be easily estimated from freely available climate data or data provided by the equipment (inverters or transformer) manufacturer. The analytical expressions can be a valuable tool for the design engineers for comparing-from the energetic point of view-different inverter types, cable cross sections, and transformer sizes without having to perform multiple detailed simulations, as the current practice is. The accuracy of the results obtained by the derived analytical expressions was tested against results obtained by detailed mathematical calculations. Furthermore, the model for the PDC and the expression for the annual energy losses on the three-phase cables are verified by comparison with measurements taken from a real photovoltaic installation during the past entire year.