Modeling and simulation of a grid-connected photovoltaic system (GCPS) is addressed in this paper to analyze its control performance and dynamics under changing irradiation. A circuit model of solar array considering irradiation is used to simulate its inherent characteristics and realized by a controlled current source. The controls of the GCPS and its electrical circuits are represented by user-defined and built-in components. The dynamic of the system in normal and fault conditions are dominated by its power controller and a method to set PI controller’s parameters is proposed in this paper. The model has been implemented on DIgSILENT. Simulation results are presented and compared with experiment waves to validate that proposed simulation model is effective for evaluation of the GCPS.