A key milestone has been reached in the construction of the largest battery park complex in continental Europe. In mid June, a 126-ton transformer was successfully delivered to the Kiisa site in Estonia by the Baltic Storage Platform, marking a major step toward commissioning this strategic energy infrastructure.
The Baltic Storage Platform is a joint venture between Estonian energy company Evecon, French solar energy producer Corsica Sole, and Mirova, a sustainable finance-focused asset manager affiliate of Natixis Investment Managers. Together, they are constructing a large-scale battery storage park in Harju County with a total capacity of 100 MW and 200 MWh. The park is expected to be commissioned in the fall of 2025.
The project involves four key partners: Connecto, responsible for building the high voltage substation; Energel, supplying the high voltage transformer; NIDEC, providing the battery technology; and WiSo Engineering, carrying out general construction works on the battery site, including installation and electrical work.
This massive transformer—transported from Turkey in a complex logistical operation—will play a central role in providing grid frequency regulation and strengthening the energy security of the Baltic states. The transformer will weigh, after being filled with oil, over 200 tons and will be approximately 10 meters high, 10 meters long, and about 6 meters wide. Its rated power is 115 MVA, operating at 330/33 kV.
In addition to the transformer, 39 out of 54 battery containers have already arrived at the Kiisa site and are being installed. These 41-ton containers, which resemble standard shipping units, are equipped with advanced cooling, heating, and fire safety systems.
“Our partners and the entire team have done a great job. Transporting a massive transformer weighing over 125 tons was undoubtedly a complex and extremely rare task for all parties involved. The challenge this time was to maximise ground pressure in connection with the underground infrastructure on site. I am happy and grateful that the transformer arrived at its destination on time. We can look forward to the future and the completion of the battery park with confidence,” said Karl Kull, CEO of Evecon.
“This type of project requires to anticipate the procurement of long-lead items from the earliest stages of development. It is a great success of our team and partner to be on schedule for this delivery, which is a complex technical equipment and a key component to be installed towards commissioning. At Corsica Sole, we are committed to high standards and our collective expertise enables us to build, a little bit more each day, a strategic energy infrastructure for Europe,” said Michael Coudyser, CEO of Corsica Sole.
The battery park substation will be the first in Estonia to connect to the electricity transmission network using a 330 kV AC underground cable, showcasing both innovation and sustainability in infrastructure development.
Once operational, the battery park will enable advanced frequency regulation for the grid. In the event of deviations in grid frequency, the batteries will rapidly respond by either absorbing or releasing electricity—ensuring a balanced and stable power system across the Baltics.
