Techno-economic analysis of utility-scale photovoltaic plants with hydraulic hydro gravity storage for self-sufficient cities

• The potential of solar photovoltaic-gravity storage is explored at 936 US sites. • The system excels in states with high insolation and purchase power prices. • The storage cost is lower than that of utility‑scale batteries at most sites. The decarbonization of the power sector necessitates reliable utility-scale storage to bridge the intermittency of renewable energy. While batteries and pumped hydro are established, they face capacity, cost, and geographical constraints. Hydraulic hydro storage offers a scalable, site-flexible gravity storage alternative, yet its deployment potential with photovoltaic systems remains unexplored. This study assesses the techno-economic viability of hybrid utility-scale photovoltaic-gravity storage plants designed to power large commercial districts. A multi-objective capacity optimization was performed across 936 locations in the United States, utilizing hourly load profiles from reference buildings and local climate data to minimize the levelized cost of electricity and loss of load probability. Results indicate that optimal balanced designs require photovoltaic capacities of 0.63–2.31 GW and storage capacities of 1.01–4.23 GWh. The system achieves high self-sufficiency (mostly < 3.2% loss of load probability) with asset-level levelized costs ranging between −0.022 and 0.198 USD/kWh, with 75% of sites falling below 0.093 USD/kWh. The levelized cost of storage is largely below 0.166 USD/kWh, proving cost-competitive against utility-scale battery systems. The proposed system outcompetes conventional grid electricity in regions including the Southwest, New England, and California. These findings demonstrate that photovoltaic-gravity storage systems provide a reliable, cost-effective pathway for deep decarbonization and bulk storage, offering substantial economic advantages over grid-only supply in favorable regulatory and climatic environments.