Increasing the value of solar: the opportunity for bulk energy storage with pumped hydro in the United States

Good solar photovoltaic generation facilities are now the lowest cost source of electricity generation. However, solar generation is highly self-correlated and not well correlated to peak demand, leading to lower prices for solar generation relative to average value in markets. Energy storage provides the opportunity to shift generation from the middle of the day to meet evening and early morning peaks. Pumped hydro energy storage is the largest and cheapest source of electricity. Sites searching indicates that there are vastly more sites in the United States than could be needed for 100% renewable electricity. Levelised cost of storage for good pumped hydro sites is low. Continued installation of solar is enhancing the ‘duck curve’ effect, increasing the viability of bulk energy storage.