OPTIMUM ENERGY GENERATION MIX IN BULGARIA

Abstract

Bulgaria’s energy generation mix has been changing rapidly in the last decade. Solar photovoltaic power (PV) has grown from 3% share of electricity generation to 16% in 2025, while coal generation has fallen from 49% to 24%. This paper explores how Bulgaria can reduce its carbon dioxide (CO₂) emissions from coal generation while keeping electricity supply affordable and dependable. Using a simplified model based on actual Bulgarian data, I determine the maximum economically viable PV penetration to be 7.8 GW, supported by energy storage of 13.2 GWh. PV generation is 10.9 GWh of which 55% is fed to the grid, 43% used to charge battery energy storage systems (BESS) and 2% is curtailed. Consumers experience a benefit of €588 million per year or a 14% reduction in electric utility bills. Return on invested capital falls to the weighted average cost of capital for PV and is above the cost of capital for BESS. The share of CO2 emissions from coal generation falls by 44% relative to 2019, which exceeds the EU guideline for the green energy transition in Bulgaria. Coal will continue to be used in the winter months but at lower levels than today, only in the four coldest months of the year, for a total generation of 6 GWh or 17% of demand. The analysis suggests there is no space for new gas capacity, while new nuclear power should be considered as replacement of existing reactors instead of capacity additions.