The paper focused on the operating characteristics of a smart-grid scheme. The power system was equipped with Distributed Energy Resources (DER) consisting of storage-integrated photovoltaic (PV) power systems. A realistic simulation scheme aiming to evaluate the DER power system behaviour under varying grid requirements was implemented in ® Matlab. The operating performance were observed in steady state and transient conditions. The action of the storage buffer was pointed out, aiming to focus on the advantages offered to the grid interactive control by using storage integrated DER units. Some discussions about the behaviour of the components and system operating characteristics were reported.Index Terms-Distributed energy resources, photovoltaic power systems, smart-grid, time-varying power flows.