Optimal Sizing of Hybrid Utility-Scale Photovoltaics and Pumped Hydro Storage Plants

A model that allows the user to optimally size a stand-alone utility-scale hybrid power supply system is presented in this paper. The system consists of two renewable energy resources: solar photovoltaics and pumped hydro storage. A brief introduction to the model's methodology is provided as an overview of the system's operations. The optimal sizing is performed using a custom-built genetic algorithm to minimise the levelised cost of energy while optimising the size of the reservoirs, reversible pumps, the static head, and the number (and type) of photovoltaics modules as well as their inverters. The model is verified using a case study in HOMER Pro, where a 2MW peak load located in Stellenbosch, South Africa, had to be supplied. The model's performance and its minimum levelised cost are presented. Additionally, a visual representation of the levelised cost of energy, the loss of power supply probability, and the influencing factors are provided to aid in system design choices. The proposed model provides more information regarding the performance of a photovoltaic and pumped hydro storage system than industry standard software and other previous studies.