This paper addresses the functional design of an energy management system (EMS) applicable to hybrid energy systems (HES) formed by the power grid, photovoltaic (PV) generators, diesel generators, and energy storage systems (ESS). The implementation of these HES and their EMS is related to the MED-Solar Project which main objective is the construction of four pilot plants in three countries of the Mashreq area (Lebanon, Palestine and Jordan), in order to show that the utilization of these systems can reduce some energy problems present in these countries and, therefore, becoming attractive for different economic sectors.