As large scale photovoltaic power plants are increasing their capacity, the new grid codes are requiring that these power plants have similar performance as conventional power plants do. Because of this, it is essential to study the performance of these power plants under different solar irradiance, temperature and electrical characteristics. As the basic unit of these type of power plants are the PV generators, the present study explains in detail the model of a PV generator: PV array, the DC bus, the PV inverter, the filter and the transformer. The control method for active and reactive power is also explained and considers the variation of ambient conditions plus the capability curves of PV generators. Finally, some simulations are developed to validate the model. © 2018 IEEE.