This paper analyzes the reality of sustainable energy supply (SEPS) from renewable energy sources (RES) as a totally green strategy of electric energy production. The paper is based on the Advanced International Policies (AIP) scenario of the European Renewable Energy Council agency forecast by the year 2040, which foresees the share of 82% of RES, extended to 100% of RES. The key element that creates conditions for achieving this ambitious scenario is an innovative solution of the so-called solar hydroelectric power plant (SHE) which is basically combined photovoltaic (PV) power plant and pump storage hydro (PSH) which can provide continuous supply of electric power and energy to consumers. Therefore, SHE is presented in this paper as the main building element of the future SEPS. For covering unit consumption of electric energy of 1 GWh in a power system, the paper calculates unit values of the SHE system: 0.73 MW of PV generator; 4,545 m(2) of PV generator; 0.36 hm(3) of reservoir volume, 0.21 GWh of PSH energy and 0.24 MW of PSH. In the case of the power system in Croatia, which is rich in solar and hydroenergy and whose climate conditions are very similar to those in the European countries, it has been shown that implementation of the green strategy of energy balance fulfilling can be realized with present day technology. Precisely, this fact shows that further increase of efficiency of SHE and other RES and their combining into RES+PHS power plants, along with increase in the cost of classic power fuels and the growing needs for environment protection, the proposed solution of SEPS realization could be widely important and thus become a serious alternative to the existing energy strategies and a guideline to decision makers in many countries.