Study on Stand-Alone Hybrid Solar Pumped Storage Systems

Currently the most promising power supply solution for remote rural areas and isolated islands far away from national utility grids is likely to be renewable energy systems (RESs), usually in the form of solar, wind, micro hydro, or hybrid systems. However, how to store the electricity harnessed from the weather and time dependent solar and wind energy sources becomes a crucial issue to utilizing RES more widely. In this study, a stand-alone hybrid photovoltaic and pumped-storage system (PVPS), based on traditional PV plant and employing a pumped hydro storage system, is proposed. The mathematical model is reported for describing the performance of the main components in such hybrid systems. The criteria for evaluating the PVPS, in terms of loss of power supply probability (LPSP) and energy utilization rate are discussed. A case study, based on a research project on a remote island off the coast of Hong Kong, is investigated using the newly developed model. The simulation results indicate that this model can help size the PV and upper reservoir (UR) optimally. The results also demonstrate that a pumped hydro storage subsystem can efficiently compensate for the intermittent nature of solar energy power generation and balance the production and demand in a remote area, thereby making the stand-alone solar energy supply more reliable and economical.