NextGrid Energy commissioned BESS Sibenik, a 60 MW / 120 MWh standalone battery energy storage facility in Croatia, with HOPS contracting its full capacity for automatic frequency restoration reserve (aFRR) services since September. The services help Croatia’s transmission system operator restore the balance between generation and consumption after system conditions change.
Located at the IMPOL-TLM industrial complex in Sibenik, the facility uses Tesla Megapack XL equipment and connects to the 110 kV network. Its 120 MWh of energy capacity provides two hours of storage at full output. The battery is designed to respond rapidly to system imbalances, rather than operate solely alongside a solar or wind farm.
The project cost approximately 60 million euros. The European Bank for Reconstruction and Development (EBRD) invested 16.8 million euros in equity, and Raiffeisen pension funds invested the same amount. IE-Energy also invested in the project. It was approved for grants of up to 19.8 million euros from the EU Modernisation Fund, but approximately 15 million euros of that funding is expected to be used because construction costs were below initial estimates.
BESS Sibenik is intended to earn market-based revenue from storage and ancillary services, rather than rely on fixed power-purchase arrangements. That model leaves commercial exposure with investors while adding fast-response flexibility to the transmission grid. NGEN worked with NextGrid Energy as a technology and operations specialist.
Development required solutions for a direct transmission connection, balancing-market participation and operating arrangements. The commissioning provides an example of battery investment moving beyond concept-stage development in Southeast Europe. The project’s performance will be watched for evidence of how balancing demand, contracting terms and market prices affect the economics of merchant-oriented storage.
