Bulgaria commissions 500 MWh BESS at thermal power plant site

Bulgaria is continuing its big battery rollout with the government announcing the commissioning yesterday (8 January) of one of Eastern Europe’s biggest battery energy storage systems to date.

The Maritsa BESS uses the existing electricity infrastructure in the Stara Zagora region. It is already active in the national electricity market, including the day-ahead and intraday markets.

It is owned by London-based independent power producer CountourGlobal, which owns and operates the Maritsa East 3 Thermal Power Plant site where the BESS is based. According to the company’s website it is leveraging existing grid infrastructure to fast-track new clean energy projects within the complex such as the Maritsa BESS.

The energy storage system is located on an area of 25, 000 square meters and is equipped with state-of-the-art technology, including 110 battery skids supplied by BYD and 28 combined power conversion systems and transformers.

“The commercial operation of our 202 MW/500 MWh BESS plant represents a significant step forward for battery storage development in Bulgaria and underscores ContourGlobal’s ability to deliver large-scale storage solutions across different markets and technologies. We have built a sizeable presence in battery energy storage, with this project in Bulgaria representing a key contribution to our 3 GWh portfolio of operating BESS projects,” commented Antonio Cammisecra, CEO of ContourGlobal.

Cammisecra added that the commissioning of the plant took place in “record time, led by local teams and supported by re-skilled personnel from the coal power plant.”

The project progressed from Final Investment Decision to COD in less than nine months, with construction and commissioning completed in just seven months and installation finalized in October 2025. More than 15 contractors and suppliers were involved in its development.

The BESS is funded by the European Union through the NextGeneration EU mechanism under Bulgaria’s National Recovery and Resilience Plan.

“The commissioning of this independent energy storage system is a guarantee for the energy security of Bulgaria,” said the country’s Energy Minister Zhecho Stankov. “The project is a vivid example of how, with the support of the state, innovation and modern technologies can be successfully combined with the existing industrial infrastructure in order to achieve a stable and reliable network.”

“Bulgaria occupies a leading place in innovation and balancing the electricity system in Southeast Europe,” added Stankov, highlighting its battery energy storage efforts. In December 2025, Bulgaria allocated more than 4 GWh of energy storage capacity across 31 projects as part of its second standalone storage procurement exercise of 2025.

Stankov claimed that Bulgaria’s total storage capacity is expected to increase “to at least 15,000 MWh” by the middle of 2026. “This means more secure supplies, better integration of renewable sources and lower prices not only for Bulgaria, but also for the entire southeastern region of Europe,” he said.