In this work an Energy Management System (EMS) prototype for an isolated renewable-based microgrid is presented. The proposed management model not only considers the management of energy sources (generation) but also includes the possibility of flexible timing of energy consumptions (demand management) by modelling controllable and uncontrollable loads. The EMS consists of two stages: first a deterministic management model is formulated and subsequently is integrated into a rolling horizon control strategy, in which the actions on microgrid devices respond to an optimization criterion related to the estimation of the future system behaviour that is continually predicted by updatable forecasts in order to reduce uncertainty in both, production capacity and energy demand. Finally, this contribution presents and discusses a case study where the results of the operation with and without optimal demand management for the same group of loads are evaluated.