Hardware Modeling of Photovoltaic Panels

Abstract – A hardware model of photovoltaic modules is proposed in this paper. The model consists in the hardware implementation of a power circuit derived from the basic circuit model of a photovoltaic cell. The current source is implemented by a current-controlled chopper, fed by a dc voltage source. The nonlinear I-V characteristic is obtained by a series array of diodes. The chopper current, smoothed by an inductive filter, represents the solar irradiance, whereas variable resistors are introduced to account for the temperature variations. The proposed model is useful for testing both the hardware and the control strate-gies of the link converters employed to connect the photovoltaic panels to the grid or to a storage unit, re-ducing the size and shooting down the cost of the whole system prototype. In this way, the laboratory tests are unaffected by the external weather conditions, and arbitrary transients or steady-state conditions can be reproduced, corresponding to the different environmental cases of interest. The current regulator of the chopper is tuned by a transfer function analysis and the behavior of the hardware model is verified by numerical simulations