Image:TagEnergy

French renewable energy developer TagEnergy has successfully put into commercial operation its 240 MW/480 MWh battery energy storage system (BESS) in Cernay-lès-Reims, now the largest operational energy storage asset in France.

Located in the Marne department, Grand Est region, the flagship project uses Tesla Megapack technology. It was developed in cooperation with French transmission system operator RTE, the SICAE de la Somme et du Cambraisis cooperative, and local authorities including the municipality of Cernay-lès-Reims and the Grand Reims urban community. The project is co-owned with Banque des Territoires, a key supporter of French BESS infrastructure.

The Cernay-lès-Reims facility more than doubles the capacity of France’s second-largest operational storage system. It also marks a major milestone for the country’s energy transition: French installed battery storage capacity has surged from below 50 MW five years ago to around 1.5 GW at the start of 2026.