The article discusses the need to use pumped storage power plants (PSPP) to increase the reliability, stability, maneuverability and energy-economic efficiency of the electric power system (EPS) with power plants based on renewable energy sources (RES), which make it possible to cover the minimum and maximum daily load schedules, and also regulating the capacities of solar-wind power plants, for which the tasks of equalizing power fluctuations and energy storage are especially important. For a technical and economic assessment and determination of the optimal parameters of a PSPP, a mathematical model is proposed under the conditions of its construction with existing structures, taking into account its water-use purpose - low-pressure, daily and seasonal operating modes, with the criterion of minimum investment, payback period, annual costs for PSPP and environmental factors with the maximum generated peak power and fuel savings. On the basis of the proposed mathematical model, a methodology and program have been developed to determine the optimal energy and economic indicators of a PSPP.The schemes of using pumped storage power plants at four energy and water facilities, that is, the Tuyamuyun hydroelectric complex, Arnasai, Talimarjan and Khodjikent reservoirs, were considered, and for these facilities, on the basis of the developed methodology and program, their energy and economic parameters of the PSPP were determined.