Thevenin´s equivalent of photovoltaic source models for MPPT and power grid studies

The model of a photovoltaic (PV) source is needed for Maximum Power Point Tracking (MPPT) and power grid studies. The single diode model can fairly emulate PV´s characteristic. The only nonlinear element in this model is the single diode. This paper proposes Thevenin´s equivalent model for a PV source by piecewise linearization of the diode characteristic. The variation of the parameters with the change in temperature and irradiance is also studied. It is shown that Thevenin´s equivalent model of PV produces a voltage-current characteristic which represents the PV source operation fairly well.