The Hertz 2 battery energy storage system has officially begun operation in Aruküla, Harju County, adding a 100MW/200MWh facility to Estonia’s rapidly expanding storage landscape.
The project is the second major installation delivered by Baltic Storage Platform, the joint venture formed by Evecon, Corsica Sole and Mirova. Together with Hertz 1, launched earlier this year in Kiisa, the two sites now form one of Continental Europe’s most powerful battery storage complexes.
With Hertz 2 completed, the combined output of the two parks reaches 200MW and 400MWh, covering a significant share of Estonia’s national storage requirements. The Aruküla installation is connected to the Elering transmission grid and will participate in fast‑responding frequency regulation markets, which have become essential since the Baltic States synchronised with the Continental European frequency area in February 2025. It will also operate in day‑ahead and intraday markets.
Estonia’s Minister of Energy and the Environment, Andres Sutt, said the projects demonstrate strong international confidence in the country’s energy sector. Karl‑Joonatan Kvell, CEO of Evecon, highlighted that “Together, Hertz 1 and Hertz 2 represent the largest private-sector investment in Estonia’s energy sector — €170 million in total.” Michael Coudyser of Corsica Sole emphasised the importance of predictable market conditions, while Raphaël Lance of Mirova noted the role of Hertz 2 in supporting Estonia’s clean‑energy transition.
The Aruküla site mirrors the technical design of Hertz 1, using 54 containerised units housing 2,328 battery modules with integrated cooling, fire protection and monitoring. Technology partners included Yuso, Connecto and Energel, with Nidec Conversion supplying the battery systems. Financing for both Hertz projects totalled €85.6 million from the EBRD, NIB and Edmond de Rothschild Asset Management.
