In this paper the integration between the Vehicle to Grid technology and a stationary energy storage system in a Virtual Power Plant (VPP) has been investigated. In order to evaluate the effects of such energy storage systems in an autonomous VPP, an Energy Management System (EMS), oriented to improve the local matching between electrical energy demand and production, has been proposed. To achieve this target and optimize the local energy production exploitation, an energy system design procedure, based on the minimization of the VPP total cost through an annual emulation of the VPP's EMS strategy, has been applied. The proposed methodology, tested on a benchmark VPP, considers the contribution of both electric vehicles and stationary battery in different possible configurations. The comparison among three different cases of study has finally presented at the aim of pointing out the technical and economic benefits.