IN Brief:
- Greenvolt Power has commissioned a 99.8MW/288.6MWh BESS in north-eastern Hungary.
- The Buj project will support frequency regulation, voltage regulation, renewable integration, and grid flexibility.
- Hungary’s storage market is moving quickly from early deployment toward larger grid-service assets.
Greenvolt Power has commissioned a 99.8MW/288.6MWh battery energy storage system in Buj, north-eastern Hungary, creating the country’s largest operational grid-scale battery asset.
Delivered after construction began in 2024, the system has a duration of roughly 2.9 hours and is designed to provide frequency regulation, voltage regulation, renewable integration support, and wider flexibility services for the Hungarian power system. Its scale places it well above Hungary’s earlier operating battery projects and gives the market a larger reference asset for grid-connected storage.
The battery is located in Szabolcs-Szatmár-Bereg County and surpasses a 40MW/80MWh system commissioned by MET Group in 2025. BYD supplied the battery units for the Buj installation, while UniCredit Bank Hungary provided project finance through a €58.9m long-tenor package.
Grant funding has also supported the scheme, with around HUF 11.3bn, equivalent to roughly €29m, contributing to the project’s capital structure. Revenue is supported by a 10-year cap-and-floor contract awarded through a Hungarian government auction, followed by merchant exposure after the contracted period.
That structure places Buj in the expanding class of European storage projects designed to combine more stable contracted income with exposure to market optimisation. Rather than depending on a single ancillary-service revenue stream, larger assets increasingly require a layered commercial model covering balancing, grid services, arbitrage, and system flexibility.
Hungary’s storage market has moved quickly from a small operational base. Grid-connected storage capacity stood at 35.3MW at the end of 2024 and rose to 73.2MW by May 2025. Forecasts point to more than 500MW of operational capacity by the end of 2026, with the market potentially reaching around 3,300MWh by 2030.
Under Hungary’s Recovery and Resilience Plan, the national target is 440MW/880MWh of new grid storage by mid-2026. Capital grants covering up to 45% of eligible project costs have helped support development, although larger deployment now places greater pressure on permitting, grid connection, equipment procurement, safety assessment, optimisation, and market registration.
Buj reflects a wider Central European shift from early battery deployment toward storage as a system asset. Frequency and voltage regulation are particularly important in grids where renewable generation is increasing, demand is changing, and balancing requirements are becoming more dynamic. Batteries can respond quickly to those conditions, provided their inverters, controls, telemetry, and settlement arrangements are properly integrated.
The project also sits within a broader European debate over how storage should be planned, consented, and operated. Safety, cybersecurity, noise, emergency response, and local planning concerns have become more prominent in battery development, with the Electricity Storage Network’s BESS planning guidance setting out many of the issues now shaping project delivery.
Installed capacity alone does not define the technical value of an asset such as Buj. A grid-scale battery depends on power conversion systems, transformers, switchgear, thermal management, fire detection, supervisory control, metering, dispatch software, and remote monitoring. Weaknesses across any of those interfaces can reduce availability, create compliance risks, or limit the asset’s ability to respond to grid events.
Storage also changes how renewable capacity is used. Wind and solar generation can create periods of surplus, congestion, or low prices, while electrification increases demand in less predictable ways. Batteries create a controllable buffer, but their value depends on location, connection strength, dispatch strategy, and market design.
Greenvolt has a 4.7GW European battery storage pipeline, including a significant presence in Poland. The Buj commissioning gives that pipeline an operational reference point in a market where storage is moving beyond demonstration projects and into the core architecture of grid flexibility.
Further project information is available through Greenvolt Power.
