In this paper a Model Predictive Control (MPC) logic, based on weather forecasts, has been applied to the analysis of power management in a domestic off-grid system composed by: Photovoltaic panel (PV), Fuel Cells (FC) and a battery pack. The controller has the simultaneous objectives of maintaining environmental comfort in the house and minimizing costs, thus optimizing the use of primary energy sources. A theoretical model of the system has been developed and simulations have been carried out for winter and summer seasons. MPC performances have been evaluated in comparison with a standard Ruled Based Control (RBC) logic.