France’s largest battery goes online
France’s largest battery storage project, a 240 MW/480 MWh system in Cernay-lès-Reims, has begun operations, marking a milestone for the country’s energy transition.
TagEnergy has commissioned a 240 MW/480 MWh battery energy storage system (BESS) at Cernay-lès-Reims in northeastern France, now the country’s largest operational battery project. The facility was inaugurated on Oct. 1 after four months of testing and is TagEnergy’s first operational storage asset in France. The Portuguese developer has built a global portfolio exceeding 10 GW across solar, wind and storage, with over 2 GW currently operational.
Connected to RTE’s 225 kV grid, the project spans just over 3 hectares and consists of 140 Tesla Megapack containers. It provides frequency containment reserve, automatic frequency restoration reserve and voltage regulation services following required simulations, tests and certifications. Civil and electrical works were carried out by Eiffage, while Tewa Solar provided project management from development through commissioning.
TagEnergy CEO Franck Woitiez stated the project demonstrates large-scale electricity storage as an industrial reality in France. During its first four months, the facility fed 70.5 GWh back into the grid and completed 145 full cycles over 125 days, according to the company.
Financing was provided by a banking consortium including ABN AMRO, NORD/LB and Caisse d’Épargne CEPAC. TagEnergy retains majority ownership after Banque des Territoires acquired a 49% stake in 2025 under a three-year partnership to finance multiple large-scale battery projects in France.