Bulgaria sold a net 3.5 terawatt hours (TWh) of electricity abroad between the start of the year and early October, data from the Electricity System Operator (ESO) show. Net exports were 2.16 TWh over the same period last year, so they are now 62% higher. Net exports mean Bulgaria sold more power abroad than it bought. The rise comes mostly from renewable energy and batteries.
Power output in Bulgaria rose by 12.24%, while use rose by 8.45%. Renewable plants produced 11.5 TWh, almost 34% more than a year ago, and account for nearly 80% of the rise in total output.
Batteries store cheap power during the day and release it when demand and prices are higher. From the start of the year to 4 October, they fed 1,720 gigawatt hours back into the grid, against just 190 gigawatt hours a year earlier. That is more than nine times as much.
The low Danube has forced Unit 5 of the Kozloduy nuclear plant to run at reduced power, and Unit 6 went into planned maintenance on 8 October. In the early afternoon that day, solar plants were producing almost 4,300 megawatts, while the whole country used 4,100 megawatts. Batteries were charging with more than 4,000 megawatts for the evening hours.
In summer, long heat waves and the low Danube cut nuclear and hydro output in the region. Bulgaria stayed a net exporter, and at times its prices were lower than in neighbouring markets. Nikola Gazdov, chair of the APSTE industry group, says prices in neighbouring countries were high and power was short. He blames limits on their nuclear plants and costly natural gas. Bulgaria, however, is making and storing more of its own power.
"The sun and batteries have greatly improved Bulgaria's energy security during one of the toughest energy crises," Gazdov said. He says this makes prices for households and business more competitive and gives Bulgaria a stronger position in the regional market.
The success rests on solar plants, batteries and the Kozloduy nuclear plant. Solar capacity has grown by about 600% since 2020 and is now close to 7 gigawatts. Storage systems are nearing 6 gigawatts and 17 gigawatt hours. APSTE estimates that about €7bn has gone into solar plants, batteries and related equipment since 2020.
Wind power has all but stalled. Bulgaria has built no large wind farm since 2013. Its wind capacity is only 716 megawatts, against more than 3.5 gigawatts in Romania and more than 6 gigawatts in Greece.
In winter, solar output falls while demand rises. Wind follows a different daily and seasonal pattern from the sun, adds to it, and can supply a lot of power in the winter months too. Gazdov says the success is not enough, and Bulgaria must also attract investment in wind farms so it has cheap local power in winter.
APSTE says private investment in wind farms and storage could top €4bn by 2030. This is possible if the authorities set clear rules and remove needless red tape, including for projects outside the zones set for faster renewable development. "This does not need new subsidies, but clear rules and a real easing of the procedures for building new capacity," Gazdov said.
The association expects the result to be more local power, more competition and cheaper prices for households and business.