The intermittent characteristic of a solar-alone or a wind-alone power generation system prevents the standalone renewable energy system from being fully reliable without suitable energy storage capability. In this study, the most traditional and mature storage technology, pumped hydro storage (PHS), is introduced to support the standalone microgrid hybrid solar-wind system. This paper explores a new solution for the challenging task about energy storage. A mathematical model of the hybrid system is developed and the operating principle is introduced. The proposed system is applied in a case study to power a remote island in Hong Kong, and its technical feasibility is then examined. The hour-by-hour simulation results indicate that the intermittent nature of the renewables can be compensated by introducing the PHS technology. Therefore, a reliable and environmentally friendly power supply can be provided. The results demonstrate that technically the PHS based renewable energy system is an ideal solution to achieve 100% energy autonomy in remote communities.