France’s largest operational BESS reaches 240 MW/480 MWh

TagEnergy has inaugurated a 240 MW/480 MWh battery energy storage system (BESS) at Cernay-lès-Reims in northeastern France, making it the country’s largest operational battery storage project.

The project, inaugurated on Oct. 1 after four months of operation, is TagEnergy’s first operational storage asset in France. Since its founding in 2019, the Portuguese group has built a portfolio of more than 10 GW of solar, wind and battery storage capacity across the United Kingdom, France, Germany, Japan and Australia, with more than 2 GW currently operational.

Connected to transmission system operator RTE’s grid at 225 kV, the project comprises 140 Tesla Megapack battery containers spread across just over 3 hectares. It entered operation after completing the simulations, tests and certifications required to provide frequency containment and automatic frequency restoration reserve services, as well as voltage regulation, supporting grid stability.

In addition to Tesla, the project involved French construction and engineering group Eiffage for civil and electrical works. Alsace-based photovoltaic and high-voltage electrical engineering firm Tewa Solar provided project management assistance from development through commissioning.

TagEnergy CEO Franck Woitiez said the Cernay-lès-Reims project demonstrates that large-scale electricity storage has become an industrial reality in France. The company said the site fed 70.5 GWh back into the grid during its first four months of operation and completed 145 full cycles over 125 days.

Financing for the Cernay-lès-Reims BESS was provided by a banking consortium comprising ABN AMRO, NORD/LB and Caisse d’Épargne CEPAC. The project is jointly owned by TagEnergy and Banque des Territoires, which acquired a stake in 2025. Banque des Territoires holds 49%, leaving TagEnergy as the majority shareholder.

It is the first joint investment under a three-year partnership intended to finance several large-scale battery projects in France. Banque des Territoires has been active in electricity storage since 2021 and currently has more than 250 MW of batteries in operation, 150 MW under construction and several hundred megawatts in development.

The institution said it plans to increase its involvement in the sector, which is expected to play a role in France’s decarbonized energy mix but still faces challenges in securing bank financing because of the relative maturity of its business model.

From pv magazine France