Harmony Energy has brought online France’s largest battery energy storage system (BESS), marking a significant step in the country’s energy transition. The 100MW/200MWh Cheviré project, located at the port of Nantes Saint-Nazaire Harbour, is the first large-scale, two-hour duration BESS in France, according to the developer. Built on the site of the former Cheviré fossil fuel power station, which operated between 1954 and 1986, the project replaces a legacy of coal, oil, and gas with a facility designed to stabilise the grid and integrate more renewable power. Using Tesla’s Megapack and Autobidder technologies, the system will provide balancing services to support the shift away from fossil-fuel peaking plants. Harmony also highlighted biodiversity and community benefits, including a fund dedicated to local social and environmental initiatives.

The energisation comes as Harmony broadens its international footprint beyond the UK, where it developed some of Europe’s largest operational BESS projects. The company previously served as investment adviser to the Harmony Energy Income Trust (HEIT), a London-listed fund that held a large UK battery portfolio. With revenues in the UK market under pressure, Harmony has focused on projects across France, Germany, and Poland. Speaking at the Energy Storage Summit in London last year, its chief investment officer described a ready-to-build pipeline in these markets. Meanwhile, HEIT itself underwent a major change in ownership. In July, energy investment firm Foresight Group acquired the trust through its Foresight Energy Infrastructure Partners II fund, taking a 49% stake directly and securing the remaining 51% via its portfolio company Blackmead Infrastructure Limited, according to Solar Power Portal reporting.

The Cheviré project reflects both France’s growing storage ambitions and the broader reshaping of Europe’s battery investment landscape.