Harmony Energy energises France’s largest BESS

August 15, 2025
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Developer Harmony Energy has successfully energised the 100MW/200MWh Cheviré battery energy storage system (BESS) project in France, at the port of Nantes Saint-Nazaire Harbour.

According to Harmony, the project is the first large-scale two-hour duration BESS in France.

Energy-Storage.news previously reported on Harmony’s announcement of the project in 2024.

The Cheviré BESS was built on the site of the former Cheviré fossil fuel power plant, which used coal, gas, and oil from 1954 to 1986. It is also situated adjacent to the grid operator’s substation.

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Utilising Tesla’s Megapack and Autobidder technologies, the Cheviré energy storage system will deliver vital balancing services to the national grid, supporting the replacement of fossil fuel peaking plants with renewable energy sources.

The project also includes biodiversity initiatives and provides commitments to supporting local social and environmental causes through a community benefit fund.

Harmony is a developer and former investment advisor for the Harmony Energy Income Trust (HEIT), a UK-listed fund that owns and manages BESS projects across the UK/GB market. These include what were at one time the two largest operational units in Europe, comparable in size to the Cheviré project.

Similar to other UK BESS owner-operators, it expanded internationally as domestic revenues declined. Paul Mason, the chief investment officer of Harmony Energy, stated at Solar Media’s Energy Storage Summit 2024 in London that the company had a ready-to-build portfolio in France, Germany, and Poland.

In the same year, HEIT said it was considering selling its entire portfolio. In July of this year, as reported by our colleagues at Solar Power Portal, the energy investment firm Foresight Group acquired HEIT. Via its Foresight Energy Infrastructure Partners II fund, the company acquired a 49% stake in HEIT. The remaining 51% was obtained through Blackmead Infrastructure Limited, one of its portfolio companies.

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