The battery park has been built in Kiisa, south of Tallinn, by the Estonian company Evecon, French solar energy producer Corsica Sole, and Mirova, a sustainable finance-focused asset manager.

The facility cost €100 million and has 54 battery containers with a total capacity of 200 MWh, Evecon said.

TSO Elering said the electricity system will need storage capacity in the future to ensure supply security.

"It is connected to Elering's grid, and right now the final approval process and prequalification for all markets is underway. On the day-ahead electricity market, the battery park has already been fully operated; we have successfully charged and fed electricity back into the grid. On the reserve market, the battery park is planned to participate already in the first months of next year," said Evecon CEO Karl-Joonatan Kvell.

Once operational, the battery park will help regulate electricity frequencies to balance the grid and "ensure a balanced and stable power system across the Baltics," the company said.

Work is already underway on a second complex in Aruküla, Harju County, which will have 400 MWh capacity.  

In October, Evecon announced that the companies had secured €85.6 million in financing from the European Bank for Reconstruction and Development, Edmond de Rothschild Asset Management, and the Nordic Investment Bank for its two battery energy storage projects, known as Hertz 1 and Hertz 2.  

More storage needed

Eesti Energia is already operating Estonia's previous largest battery storage unit in Auvere, Ida-Viru County, with a capacity of 26 megawatts.

Elering's recent report highlights that by 2035, Estonia will need thermal power plants with a capacity of 1,700 megawatts and storage of 400 megawatts to ensure supply security.

"This forecast is based on grid connection requests. It's a realistic volume that can be built by that time. I believe it will actually be higher by then, because if we look at the interest in storage solutions in the Baltics today — Lithuania, for example, has 4,000 megawatts — then that ten times more. I believe Estonia will also be somewhat higher. But of course, to avoid repeating what happened with solar panels, where overinvestment made things difficult for all investors, we have to be cautious," said Eesti Energia board chair Andrus Durejko.

Elering board member Erkki Sapp said interest in building batteries and storage units is high because storage helps reduce price spikes.

"The strengths of storage units are that they respond quickly and are highly flexible, which is why they play an important role in providing frequency reserves, where fast response is needed to maintain balance in the power system. At the same time, storage also works successfully against the day-ahead electricity market, shifting electricity from zero-price hours to higher-priced hours and thereby smoothing peak prices," Sapp said. 

This article was updated to add additional context.

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