Neoen launches construction plan for France’s largest battery, a 496 MWh grid asset near Paris

Neoen has unveiled plans for a 248 MW/496 MWh battery in Vernou-la-Celle-sur-Seine, east of Paris, that it says will become France’s largest storage asset and the first connected to RTE’s 400 kV transmission network. Construction is scheduled to begin in the summer of 2026, with operations expected in 2028.

Neoen’s Vernou-la-Celle-sur-Seine project reaches a new phase

The French renewable developer said it has signed a contract with Nidec ASI for the battery’s construction. The project will sit about 90 kilometers southeast of Paris and is designed to support the electricity network in the Île-de-France region, where grid congestion has become a practical constraint on power delivery.

At the point of connection, the battery is rated at 200 MW. Neoen said the system will provide frequency and voltage regulation services, two of the core functions that allow storage to stabilize a grid with rising shares of renewable generation.

French assembly and long-term maintenance are part of the package

Nidec ASI will supply the battery modules, which are to be assembled in France at a new facility near Saint-Étienne. The company will also handle maintenance for 20 years, giving the project a long operational support window that goes beyond commissioning.

Neoen said the order also supports Nidec’s plans to expand production capacity in France. That domestic assembly step matters in a market where grid-scale storage projects increasingly depend on local manufacturing content, system integration expertise and long-term service commitments.

Why this battery matters for France’s grid

The project’s scale and connection point make it more than a routine utility battery. Neoen said the system should help relieve congestion in the Paris region while enabling higher penetration of renewable energy, a reminder that storage is becoming a grid infrastructure tool as much as a clean-energy add-on.

The company said the site will also include further environmental studies before construction begins and a local engagement process with officials and community representatives. Neoen described the battery as part of its wider storage portfolio in France, where it says the company now has 2.2 GW under construction, in operation or under management across solar, wind and battery assets.