The foundation of the most powerful battery park in Continental Europe is being installed at Kiisa 

WiSo Engineering, a company specialising in the construction of energy installations, is constructing the first part of the largest battery park in Continental Europe at Kiisa as ordered by Baltic Storage Platform, with completion already scheduled for this autumn. The park, with an output capacity of 100 MW and a storage capacity of 200 MWh, will provide a significant contribution to the stability of the Estonian power grid. 

“Kiisa Battery Park will reinforce and stabilise the Estonian power grid by providing frequency reserve and smoothing out fluctuations in prices. It has a noteworthy connection capacity and it will allow for rapidly and efficiently responding to any changes in the frequency of the power grid once it commences operation in the autumn. Therefore, the solution supports the security of the supply of the entire region and allows for more efficient integration of various types of renewable energy sources,” said Risto Virveste, Head of High Voltage and Grid Integration of WiSo Engineering OÜ. 

Cutting edge battery technology by the Japanese company Nidec is used for the construction of the battery park. “We will soon receive the first battery modules with thousands of battery elements installed in them. These large battery modules resemble shipping containers to the untrained eye,” noted Virveste. 

As an integrated system, the battery park will be capable of rapidly responding to any fluctuations in the power grid, if necessary. Ensuring the stability of frequency is one of the most essential components of the operation of the national power grid. 

“The construction of such an innovative and large-scale complex is extraordinary for WiSo Engineering, as a storage system of this size has not been built before in the energy sector,” Virveste added. 

According to Karl Kull, representative of Evecon, the project serves as a major step towards ensuring Estonian storage goals. “While building the biggest battery farm in Continental Europe together with the Estonian company WiSo Engineering, we need to bear in mind that this is a historic moment for the entire Estonian energy sector, but also for our region with respect to synchronisation with the European grid,” said Kull. “In addition to the unprecedented capacity of the storage system, the site boasts the already installed underground cable operating at 330 kV voltage – unique in Estonia – for connecting the battery park and the Estonian transmission network. Usually, 330 kV overhead transmission lines are used for such solutions,” Kull added. 

Baltic Storage Platform – the largest battery energy storage system in Continental Europe 

WiSo Engineering OÜ, the Estonian company responsible for general construction and electricity work for the Kiisa Battery Park project, has emerged from the local energy company Evecon. The latter company founded the joint venture Baltic Storage Platform along with the French solar energy producer Corsica Sole and the French investment fund Mirova. 

The joint venture will construct two battery energy storage systems in Harju County with a total output capacity of 200 MW and a total storage capacity of 400 MWh. The battery energy storage system at Kiisa will be completed this autumn, while the system at Aruküla will be completed in spring 2026. These battery parks will play a key role in the Estonian energy system after the desynchronisation of the Baltic countries from the Russian grid. 

WiSo Engineering is growing rapidly and the portfolio of the company already comprises 13 renewable energy projects, including the largest solar farm in the Baltics. The company additionally entered into a contract last spring with TEK Transformatör, the leading Turkish transformer manufacturer, which will create additional possibilities for the construction and modernisation of energy parks in the entirety of the Nordic and Baltic regions.