Greenvolt commissions Hungary’s largest battery storage system

Greenvolt Power, the Polish unit of Portugal’s Greenvolt Group, has commissioned the Buj battery energy storage system in Szabolcs-Szatmár-Bereg County, northeastern Hungary, replacing the 40 MW/80 MWh facility commissioned by MET Group in mid-2025 as the country’s largest operational storage asset.

The project, which reached full operations in June 2026 following construction that began in 2024, has a duration of about 2.9 hours and will provide frequency and voltage regulation, grid flexibility services, and renewables integration support to Hungary’s transmission system operator, MAVIR (Magyar Villamosenergia-ipari Átviteli Rendszerirányító).

Financing was provided by UniCredit Bank Hungary, which supplied EUR 58.9 million in project finance with a tenor of more than 10 years. The project also received HUF 11.3 billion, approximately EUR 29 million, in grant support. Revenue is underpinned by a 10-year cap-and-floor contract awarded through a Hungarian government auction, with merchant market exposure thereafter. BYD supplied the battery units.

The Buj BESS arrives as Hungary scales its grid storage ambitions rapidly. Grid-connected capacity stood at 35.3 MW at end-2024 and reached 73.2 MW by May 2025. Analysts forecast more than 500 MW of operational capacity by end-2026, with the market reaching an estimated 3,300 MWh by 2030. Hungary’s National Recovery and Resilience Plan targets 440 MW/880 MWh of new grid storage by mid-2026, supported by a capital grant program covering up to 45% of project investment costs across a EUR 160 million budget.

Greenvolt has a 4.7 GW European battery storage pipeline, including a significant presence in Poland.