One of the Baltic states' largest solar parks is located in Kirikmäe and construction work now underway will expand it into a hybrid power plant.

French investment firm Mirova and Estonian energy company Evecon are adding a 55-megawatt battery storage system with a capacity of 250 megawatt-hours to the already operational 77.5-megawatt solar park.

Their joint venture, Baltic Renewable Energy Platform (BREP), began construction of the battery storage system in January. The main contractor is WiSo Engineering and equipment is being supplied by Huawei. The battery facility is expected to become operational in the third or fourth quarter of this year.

According to the company, the hybrid system will enable it to store solar energy and provide services essential to grid stability, including frequency containment reserve, automatic frequency restoration reserve and manual frequency restoration reserve.

BREP has signed a 10-year flexibility and power purchase agreement with German energy company Pure Energy, covering output from the Kirikmäe, Imavere and Lohu Metsa parks. The company said it is the first agreement of its kind in the Baltic states.

The project is being supported by a financing package of nearly €85 million from Swedbank. In addition to the construction of the battery park, the sum includes other financial instruments.

Later this month, construction will also begin on a second battery storage facility. Diotech OÜ and Transcom AS will build a battery power plant in Tsirguliina with a capacity of 100 megawatts and storage capacity of 200 megawatt-hours.

According to its developers, Project Zirgu will be the largest battery industry park based entirely on Estonian capital, aimed at helping balance the electricity market in Estonia and the Baltic region and mitigating price volatility.

Zirgu has secured a high-voltage grid connection from Elering, the necessary properties and building permits and has completed the required procedures to begin construction in February. The initial investment capital has been raised from the shareholders of Diotech and Transcom.

"The project can already be implemented using our own funds. At the same time, we are analyzing additional financing options to optimize the capital structure and develop subsequent projects in parallel," said Paul-Kristian Padrik, one of Diotech's shareholders.

In the first phase of construction, the high-voltage grid connection and substation infrastructure will be built to allow the complex to be expanded within six to nine months — if market demand and price volatility persist — to 200 megawatts and 800 megawatt-hours of capacity. That would make it the largest battery power plant in the Baltic states.

The Zirgu battery power plant is scheduled for completion in March 2027. The first phase of the project involves an investment of approximately €35 million.

Kätlin Klemmer, communications specialist at Elering, told ERR that 245 megawatts of battery capacity have so far been connected to the grid in Estonia.

Asked how much room remains for additional capacity, she noted that since amendments to the Electricity Market Act entered into force last year, Elering has been required to develop the electricity grid to ensure that all viable generation capacity is guaranteed a production-oriented grid connection.

"As a rule, there is capacity in Elering's 330-kilovolt network to connect large production units and our long-term plans also foresee additional generation volumes being added," Klemmer said.

She added that any additional project-based grid reinforcements, which depend on the specific location and are generally more localized in nature, would be initiated by Elering after a grid connection agreement is signed and the connection fee is paid.

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