Dynamic simulation modeling is so important to predict the energy production of Photovoltaic (PV) systems. It is needed to make informed technical and economical decisions. The simulation models of PV systems in literature are good enough for steady state analysis, but they are not suitable for dynamic analysis of grid operating and control conditions. This paper proposes a dynamic PV model suitable for Decentralized Generation (DG) applications. The proposed model relates the electrical output of the PV system to various input and environmental parameters. The model is developed in Matlab-Simulink environment, and it is validated comparing the developed PV performance characteristic curves with those of the manufacturer's data sheet and those developed by a commercial software package for a Solarex-MSX 60W PV type.