In this paper, an electrical energy system comprising three energy sources, namely PV, fuel cells, and batteries is proposed to provide the power requirement for an Eco-House. A systematic system sizing was used to determine the minimum capacity of the system components to assure reliable electricity supply to the Eco-House. Actual load data for a typical Omani house with similar size as the eco-house was considered as the stand-alone load with an average energy consumption of 41 kWh/day and 4.7 kW peak power demand. Dynamic modeling and simulation for each renewable energy sources was done by MATLAB. Transient responses of the system for a step change in electrical load is presented.