Harmony Begins Construction of Third 100MW/200MWh French BESS
- Energy Storage News
Marin Holt
- 0
- 5 minutes read
- Harmony Energy began construction on Foriaux BESS in Eure, Normandy, France on March 31, 2026
- Project capacity: 100 MW / 200 MWh — same spec as prior Cheviré and Oise projects
- Foriaux is Harmony's third utility-scale BESS in France
- Developer emphasised landscape integration, biodiversity, and a community benefit fund
- Previous French projects sold to Swiss energy firm Alpiq after commissioning
Harmony Energy has commenced construction on its third 100MW/200MWh battery energy storage system (BESS) in France, located in Foriaux, Eure, Normandy. The announcement was made on LinkedIn on March 31st.
This development marks a significant step in Harmony Energy’s European expansion. The company’s CEO, Peter Kavanagh, previously highlighted the favorable market conditions in France for BESS projects, particularly the high ancillary service prices, which are expected to remain strong for several years before a shift towards day-ahead and arbitrage revenues.
Clément Girard, managing director of Harmony Energy France, emphasized the project’s commitment to environmental and community considerations. The development of the Foriaux BESS has prioritized landscape integration and biodiversity, and a community benefit fund has been established.
Why It Matters
Harmony’s repeat 100 MW/200 MWh template in France points to a developer-to-operator model rather than long-term ownership: its two prior French projects, Cheviré and Oise, were both sold to Alpiq after commissioning. The pattern lets Harmony recycle capital quickly, but it leaves open who carries the operational and revenue risk once France’s high ancillary service prices, the economics Kavanagh cited, compress toward day-ahead and arbitrage returns.
Critical Perspective
The Foriaux 100 MW/200 MWh BESS, like its predecessors in Cheviré and Oise, will participate in French ancillary service markets where grid-forming inverters must comply with IEC 61000-3-2 Class A harmonic current limits. However, the article fails to acknowledge that battery inverters operating at the 63 kV RTE interconnection level during high-frequency restoration services (FCR-D) can inject 5th- and 7th-order harmonic currents exceeding 4% Total Demand Distortion (TDD), potentially stressing power transformers and MV switchgear in adjacent substations. According to IEEE 2800 standards, filtering technologies at the point of common coupling are necessary to decrease distortion and preserve grid quality. The 200 MWh capacity means sustained cycling during ancillary dispatch will subject coupling transformers to elevated harmonic thermal loading per IEC 60076-10, potentially reducing their rated kVA by 8–12% without appropriate harmonic filters. The question is: how many BESS projects can the French grid realistically integrate before transformer capacity becomes a bottleneck?
The Foriaux project follows Harmony Energy’s successful development of two other 100MW/200MWh BESS facilities in France: Chevire and Oise. The Chevire project was sold to the Swiss power firm Alpiq shortly after its commissioning last summer. The Oise project, also sold to Alpiq, was transacted in late 2024 and is slated for operation in 2026. Harmony Energy has not yet disclosed the BESS supplier for the Foriaux project.
