This paper proposes methodological approaches to assessing the impact of renewable energy and energy efficiency development on emerging economies’ energy security. It is suggested to supplement the current methodology for assessing energy security with the decoupling index of the renewable energy financial burden on the state budget, the energy efficiency decoupling index, the households’ energy poverty indicator, the index of capacity development for balancing electricity generation volumes, and the energy fluctuations indicator. These indices provide a comprehensive assessment of energy security under the latest challenges. Thus, the COVID-19 pandemic in the Ukrainian energy sector led to the “green and coal paradox”, when the government decided to keep green electricity generation but limit nuclear generation. It required increased flexible capacities (thermal generation) and led to a rise in electricity prices and environmental pollution. Forecasting energy fluctuations with Butterworth filters allows minimizing the risks of maximum peak loads on the grid and timely prevention of emergencies. The energy fluctuations within the 20% range guarantee energy security and optimal energy companies’ operation. It is proposed to smooth out energy consumption fluctuations through green energy development, smart grids formation, energy efficiency improvements, and energy capacities balancing to ensure energy and economic sustainability.

This paper deals with improving the feed-in tariff policy for green energy advancement in Ukraine’s households based on assessing the economic efficiency of investment project implementation under the current state support mechanisms. This study was conducted for solar and wind power plants with different installed capacities. The Levelized Cost of Electricity and the payback period for such power plants were calculated considering the ongoing feed-in tariffs and discount rates determined by various equity and debt capital ratios. The results showed that the state support provides attractive payback periods for solar and wind power plants with an installed capacity of ≥30 kW. In comparison, 5 kW solar power plants and wind power plants with a capacity of up to 10 kW are not paid off during the power plants’ lifecycle. It confirmed that the ongoing energy policy in Ukraine’s residential sector is still designed to obtain profits by the owners of generating facilities by selling the excess electricity. In the meantime, its main goal—providing households energy independence—has been levelled. To resolve the issues caused by such a state support model, a methodical approach to improve the feed-in tariff calculation is proposed. In addition, recommendations for reconsidering other policy measures to ensure effective renewable energy development in the residential sector have been made.

On-grid hybrid wind–solar systems are one of the best sustainable solutions for developing distributed generation, as they can provide a stable and reliable electricity supply, effectively using the potential of the two most common renewable energy resources. In Ukraine, promoting the development of on-grid hybrid wind–solar power plants takes on particular importance under conditions of electricity shortages caused by the large-scale destruction of the energy infrastructure due to the ongoing hostilities. This article examines the economic efficiency of installing such power plants in the residential sector of Ukraine under different state support schemes. This study was conducted for on-grid hybrid wind–solar systems of various configurations and installed capacities with different equity and debt capital proportions involved in implementing investment projects. This study’s results highlight the economic efficiency of the feed-in tariff compared to the net billing for households investing in such facilities and emphasize the need to improve policy measures to increase their investment attractiveness.