Two large-scale battery energy storage projects have broken ground in Western Europe within the same reporting period, signaling continued momentum in grid-scale storage deployment across the continent.

RWE Moves Forward in Germany

German energy company RWE has begun construction on a 236 MW / 470 MWh battery energy storage system located in Germany. The project represents one of the larger grid-scale storage installations currently under development in the country, and reflects RWE's ongoing effort to expand its flexible generation and storage portfolio as the German grid continues its transition away from fossil fuels.

No completion date for the RWE facility was specified in available reports, though the scale of the project places it among the more substantial standalone storage builds underway in Central Europe.

Kallista and Envision Break Ground in France

Simultaneously, French independent power producer Kallista Energy and China-based Envision Energy have commenced construction on a 193 MW / 386 MWh battery storage facility at Neuilly-en-Thelle, France. The project marks the second battery storage collaboration between the two companies in France, suggesting a deepening commercial relationship between the French developer and the Chinese equipment supplier.

According to available reports, the Neuilly-en-Thelle system is expected to begin providing frequency-regulation services to the French national grid by 2028. Frequency regulation is among the most technically demanding grid services that battery systems can perform, requiring rapid charge and discharge cycles to help balance real-time supply and demand fluctuations across the transmission network.

Envision Energy is supplying the storage technology for the French project. The company has been active in European storage markets as Chinese battery and energy equipment manufacturers seek to expand their presence beyond domestic deployments.

Scale and Context

Together, the two projects account for roughly 856 MWh of new storage capacity entering active construction in Europe, spanning two of the continent's largest electricity markets. Both Germany and France have been expanding grid support mechanisms for battery storage as their respective grids absorb higher shares of variable renewable generation from wind and solar.

The German project, developed by RWE, is approximately 22 percent larger in energy capacity than the French facility. RWE has previously developed battery storage assets in multiple European markets as part of a broader portfolio diversification strategy following its exit from coal generation.

The Kallista-Envision partnership at Neuilly-en-Thelle underscores the role that bilateral developer-supplier relationships play in accelerating project pipelines. By working with the same supplier on successive projects, developers can streamline procurement, permitting preparation, and technical integration processes.

Outlook

The near-simultaneous construction starts in Germany and France reflect a broader European pattern in which grid operators and regulators are increasingly structuring market rules to compensate large batteries for the ancillary services—such as frequency response—that were historically provided by thermal power plants. As those plants retire, storage systems are being positioned to fill part of the resulting flexibility gap.

The French project's 2028 target for entering frequency-regulation service indicates a construction and commissioning timeline of approximately three to four years, consistent with the permitting and build-out schedules seen on comparable projects elsewhere in Europe. No operational timeline was reported for the RWE installation in Germany.