Identification of Model Parameters of the Photovoltaic Solar Cells

Presently, many equivalent circuit models have been developed and proposed to describe the photovoltaic (PV) cell's characteristics, and the most commonly used are single and double diode models. In a single diode model, a complete characteristic of a PV cell's can be described by five model parameters i.e.: light generated current, leakage or reverse saturation current, diode quality factor, series resistance and shunt resistance. Light generated current and reverse saturation current can be said as external influences meanwhile the others are internal influences. Accuracy of the PV system modelling is depending on the correct calculation of the internal influences. A research preliminary in order to identify internal influences have been performed and will be presented in this paper. As a research subject, polycrystalline silicon (wafer based crystalline silicon technology) and amorphous silicon (thin film technology) modules, as components of grid-connected PV array system at Szent István University (SZIU), were used under Gödöllő climatic conditions. As an initial step, simulation results based on software packages (associated with the PV characteristics) and some calculation methods to identify internal influences are shown here. As a long term outcome of this research, internal parameters of both modules can be predicted, and furthermore PV cell's model for both modules can be developed.