This paper presents the model for optimal sizing of a Solar Thermal (ST) power plant with parabolic collectors, which operates with Pump Storage Hydroelectric (PSH), all for the purpose of providing full energy independence of an isolated consumer. The sustainability of such system is based exclusively on solar energy input (without hybridization with any fossil fuel), as a renewable and pure energy resource, and the use of hydro energy, due to the possibility of its continuous production of energy. The feasibility and characteristics of the ST-PSH power plant were tested on power supply of the Island of Vis in Croatia, and the results show that the proposed model describes the operation of the power plant very well. For average solar irradiation of about 1500 kW h/m(2)/a, precipitation 644 mm/a, evaporation 1444 mm/a, volume of PSH upper reservoir of 20 h m(3), electric energy consumption of 18 GV A h/a and reserve in the system for 3-4 months, the obtained power of the ST power plant is 22 MW, which can produce unit value of the annual thermal energy of 459 kW h/m(2)/a and electric energy of 160 kW h/m(2)/a, while the total collector aperture in the observed case is about 16 ha. These results show that ST-PSH plants can be successfully applied on locations with relatively low irradiation, wherein the key element that ensures continuous production of energy is precisely the PSH technology that can in the best way, in economic-technical, and especially in ecological sense, balance the relatively large summer surpluses and winter energy shortages. (C) 2011 Elsevier Ltd. All rights reserved.