The aim of this project is the development of an energy management technique for a Sea Water Reverse Osmosis (SWRO) desalination plant in the small village of Ginostra in Sicily. The desalination plant has not been realised yet and only a preliminary project is available from ENEA, the Italian Agency for Energy, Environment and New Technologies [ENEA (Italian Agency for New Technologies, Energy and Environment), Impianto di Dissalazione a Ginostra, Isola di Stromboli - Progetto preliminare. Internal Project Docurnentation]. The energy needed to perform the desalination process will come from the 100 kWp PV-Diesel hybrid system that supplies the islanders whose installed power will be expanded to 125 kWp. This system has been sized for the energy demand of the summer months when the population is much higher. This results in the production of a large amount of excess PV energy that remains unused from October to May. The desalination system has to provide a local source of fresh water (at the moment water is periodically supplied by a tank ship) through the use of as much excess PV energy as possible. Thus, the aim of the energy managernent system is to run the desalinator with the smallest possible amount of diesel produced energy, and with the largest possible amount of PV excess energy. An energy management technique is here proposed and an hourly simulation of the combination of the hybrid system with the desalination plant is performed. Results for energy consumption with and without the proposed energy management technique are presented and the number of diesel operational hours has been taken as the discriminating parameter.