Neoen’s battery will pioneer network-building services on the French transmission network – SPE

By ESS news

Renewable energy developer and operator Neoen has signed a contract with French transmission system operator RTE to improve the stability of the French electricity grid. The 92 MW/183 MWh Breizh Big Battery, currently under construction, will provide grid-building services as part of a trial conducted with Réseau de Transport d’Electricité (RTE) to retrofit inverters.

The grid-forming technology has passed the experimental phase and is now deployed to support energy systems with a high penetration of renewable energy sources. However, in France, all existing battery storage facilities are currently operating in grid-following mode. These systems are ‘follower’ by design and are slower to respond and provide limited support for fluctuations in electricity supply and demand.

Unlike traditional grid-following inverters that rely on existing grid voltage and frequency references, grid-shaping inverters actively replicate the key behaviors of synchronous generators – such as inertia, frequency regulation and voltage regulation – using advanced control architectures. This capability allows inverter-based resources – such as batteries and solar plus storage systems – to provide essential stability services to the grid, making them critical to reliable grid operation, with deployments already proving effective in real-world projects around the world.

To assess the benefits of this approach, RTE and Neoen have started an experiment to convert an inverter from grid-following to grid-forming mode, which will last at least a year. Once deployed, the Breizh Big Battery will become the first battery in France to offer these enhanced capabilities.

The project in the village of Pleyber-Christ in Finistère will be one of the largest batteries in France and the largest in the Brittany region. It is expected to be operational in the summer of 2026.

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