Bulgaria’s Battery Boom Shields Power Sector From Drought Shock

Bulgaria is benefiting from a rapid expansion of battery energy storage systems as record drought hits electricity generation across Eastern Europe, according to an Agence France-Presse (AFP) analysis from Sofia.

Around 100 battery energy storage sites are currently operating in Bulgaria, most of them constructed during the past two years.

The large-scale facilities have been developed on former industrial sites and airfields, as well as alongside existing power plants, including coal-fired facilities.

“The scale and speed at which energy storage systems are being built in Bulgaria are unprecedented in a European context,” Stavros Papathanasiou, a professor at the National Technical University of Athens, told AFP.

Experts attribute Bulgaria’s prominent position in the region to relatively limited administrative hurdles, an energy market open to clean power and funding from the European Union.

The batteries store excess electricity produced by solar plants and return it to the grid when demand increases.

That capacity became particularly valuable after exceptionally low water levels in the Danube disrupted electricity production from nuclear and hydroelectric plants across Eastern Europe and increased demand for imported power.

Bulgaria, one of the EU’s poorest nations, registered monthly net electricity exports of about 830 gigawatt-hours in July and August. The figure was more than twice the average recorded in May and June.

Romania received almost half of Bulgaria’s electricity exports in July, worth approximately €74 million ( million).

At Maritsa East 3, once Bulgaria’s second-largest coal-fired power plant, the move away from coal is already apparent.

The facility was constructed during the communist era with four generating units and sharply reduced its coal use in 2024, while its existing grid infrastructure was adapted for a battery energy storage system.

“We were able to utilize the existing major connection to the power grid. We decided to take one coal unit offline and connect batteries instead,” said Vasil Shtonov, ContourGlobal’s head of operations in Bulgaria.

“Coal out, batteries in. It was the right place at the right time,” Shtonov told AFP. He also stressed that Bulgaria needs to retain a minimum level of coal-fired capacity to cope with severe winters or possible interruptions to gas supplies.

Bulgaria represented about 9% of newly installed battery energy storage capacity in Europe in 2025, while accounting for around 2% of new solar capacity.

Lennart Herrmann of the Munich-based research and consultancy firm FfE said Bulgaria could “serve as a positive example for other European nations.”

“The right incentives can enable a rapid energy transition,” he told AFP.

Bulgaria’s Ministry of Energy said that the country has about 5.7 gigawatts of operational battery energy storage capacity as of this month.

That capacity represents almost one-quarter of Bulgaria’s total installed electricity generation capacity and exceeds the operational battery storage capacity of neighboring Romania by more than five times.

Bulgarian companies have already contracted nearly 14 gigawatt-hours of large-scale storage capacity, with some of those systems already in operation.

“The goal is for storage systems to find a sustainable place in the market,” the Energy Ministry said, adding that this “must go hand in hand with other investments, such as in the transmission and distribution networks.”

Nikola Gazdov, chairman of the Bulgarian Association for Electricity Production, Storage, and Trade, said the expansion of battery storage resulted from several factors rather than a deliberately designed strategy.

“It all happened almost by accident,” he said.

Solar and wind generation capacity is growing quickly across the region, but Bulgaria’s renewable energy expansion is concentrated heavily on solar power, creating increasingly large electricity surpluses during daylight hours.

Gazdov said large-scale battery projects in Bulgaria can be constructed and brought into operation within nine to 18 months, considerably faster than many solar or wind projects.

Battery storage, however, also has limitations.

Cross-border electricity connections with neighboring countries have restricted capacity for transmitting power.

Modern batteries also hold electricity for relatively short periods. Herrmann of FfE said this is “usually between one and six, and sometimes up to eight hours.” As a result, batteries can help the grid during temporary supply shortages but cannot substitute for a nuclear reactor taken offline because of drought.

The growing success of battery storage could eventually hurt the profitability of the systems themselves, as an increase in operators buying electricity when prices are low and selling it during peak periods would narrow the price difference between those periods.