en.Wedoany.com Reported - Baltic Storage Platform, a joint venture established by Evecon, French electricity producer Corsica Sole, and international investment fund Mirova, has officially commenced commercial operations for the 100 MW battery energy storage project Hertz 2 in Aruküla, Estonia. Together with its sister project Hertz 1, which was commissioned in February 2026 in Kisa, the two battery parks have a combined capacity of 200 MW and an energy storage capacity of 400 MWh, forming one of the largest battery energy storage system complexes in continental Europe.
Hertz 2 is connected to the transmission grid operated by Elering and will participate in a range of electricity market transactions. Since Estonia's grid synchronized with the Continental European frequency zone in February 2025, this battery energy storage system can provide fast-response frequency regulation services, which are critical for the stability of the Baltic power system. Additionally, the BESS will participate in conventional day-ahead and intraday electricity markets.
Minister of Energy and Environment Andres Sutt stated that foreign investment is of immeasurable importance to Estonia's economic development, and the Hertz 1 and Hertz 2 projects are crucial for balancing the entire power system and introducing more renewable electricity to the market—exactly the kind of flexible capacity Estonia increasingly needs as it maintains its own frequency among the Baltic states.
Evecon CEO Karl-Joonatan Kvell added that Hertz 1 and Hertz 2 together represent the largest private sector investment in Estonia's energy sector, totaling €170 million. The investment decision was made at the end of 2023, entirely against market trends, without any subsidies, with all risks borne by the companies themselves. With Hertz 2 now operational, the BESS complex, along with Hertz 1 in Kisa, is fully running, helping the Baltic power system maintain frequency and reduce price spikes.
Corsica Sole CEO Michael Coudyser noted that Hertz 2 was built quickly and smoothly based on the same technical solution as Hertz 1. Given the limited capacity of the Baltic frequency market, it is crucial for the state to ensure a level playing field for all market participants; a predictable and fair market allows private investment to deliver maximum value to the system.
Mirova Head of Private Assets Raphaël Lance concluded that the completion of Hertz 2 is a new milestone in Mirova's commitment to investing in clean energy in Estonia. With the batteries now operational, the stability of the legal environment and the transparency in operating these batteries are essential for investors to maintain confidence in funding new companies and infrastructure.
After disconnecting from the Russian grid, the Baltic states have had to maintain the frequency of their power systems independently since February 2025. Hertz 2 responds to frequency fluctuations and unexpected disturbances within milliseconds, helping to maintain the balance between production and consumption in the grid. Large-scale battery storage plays an increasingly important role in integrating renewable energy into the market and mitigating electricity price volatility. Hertz 2 stores electricity when market prices are low—which typically means a large amount of renewable electricity is being produced at that time—and feeds the stored energy back into the grid when prices and demand are high, both capturing surplus renewable energy that would otherwise be wasted and reducing extreme price spikes experienced by consumers.
Located in Aruküla near Tallinn, Hertz 2 is technically a complete replica of Hertz 1. The park is based on a containerized solution, with 54 containers housing a total of 2,328 battery modules. Each container is equipped with battery racks, as well as cooling, fire protection, and monitoring systems, forming a safe and independent unit. The project was completed in collaboration with transmission system operator Elering and technical and engineering partners including Yuso, Connecto, and Energel.
The battery energy storage system used in the park is supplied by Nidec Conversion, and its subcontractor responsible for the construction and electrical engineering of both Hertz battery parks in Estonia is WiSo Engineering. The construction of Hertz 1 and Hertz 2 was financed by an €85.6 million loan from the European Bank for Reconstruction and Development, the Nordic Investment Bank, and Edmond de Rothschild Asset Management, with legal matters advised by law firms Rask and Cobalt.
