Harmony Energy has completed the sale of its 100 MW / 200 MWh Cheviré battery energy storage system (BESS) in France to Alpiq, a Swiss electricity producer and energy services provider.

The transaction marks the second Harmony Energy project in France acquired by Alpiq and the first to be fully developed, constructed and brought into commercial operation by Harmony Energy prior to sale.

Located at the Port of Nantes Saint-Nazaire Harbour, the Cheviré project is France’s first operational large-scale, two-hour-duration battery storage facility. The project uses Tesla Megapack technology alongside Autobidder software. It was energized in August and officially inaugurated in December.

“The development, construction, grid connection and commissioning of France’s largest battery storage facility took just three years, a remarkably short timeframe for a project of this scale,” said Andy Symonds, CEO of Harmony Energy France.

Construction began in summer 2024, with the project achieving energisation within a year. The facility is built on the site of the former Cheviré fossil-fuel power plant, which operated for more than three decades.

Under the terms of the sale, Harmony Energy will continue as asset manager, overseeing performance and operational optimisation of the site.

Cheviré becomes Alpiq’s second asset in France. A further 100 MW / 200 MWh BESS project in La Corne-en-Vexin, also acquired from Harmony Energy in 2024, is currently under construction and is expected to become operational by 2027.