The paper analyses the opportunity of 100% RES scenario promotion for R. Moldova. In this respect economic simulations are used. The paper shows that only 70% of the demand could be covered directly from wind farms and photovoltaic energy sources (WPES), the installed power of which should be 2.44 higher than the maximum power of annual demand. The remained 30% of energy (RE) - by energy storage system (ESS) with a capacity (kWh) of 32% from RE and a power (MW) of 87% from maximum power demand. As country doesn't have its own hydro reserves, Li-ion batteries are considered for ESS. The investment in such SSE would exceed 3-52 times national GDP and that makes unrealistic 100% RES scenario for R. Moldova. As analysis showed, there are more than 1400 cases/episodes within the year when energy to cover daily demand cannot be accumulated during 1 to 4 days. By reducing SSE capacity to a value equal to the daily energy demand and maintaining ESS power, it was found that the levelised tariff of WPES+ESS scenario exceeds, however, those of traditional scenarios. Only 5% of energy produced by WPES can be accumulated in such ESS, the remaining 25% - by importing electricity during the night when the price for electricity is the lowest, in the calculations above taken at negligible level. Subsequent improvement WPES+ESS scenario is seen by modifying WPES installed power, involving gas turbines, using ESS for system services.