Eesti Energia and Emsys VPP Reach Milestone: Baltic Solar Park Approved for Frequency Control Markets
Tallinn, Estonia / Oldenburg, Germany – The Estonian energy utility Eesti Energia and the Oldenburg-based company Emsys VPP have successfully prequalified one of the largest solar parks in the Baltics for participation in frequency markets. This milestone represents a significant step forward and highlights that solar power plants can function as flexible elements in the electricity system and contribute to grid stability.
Sopi Solar Park in Estonia: Largest Solar Facility in the Baltics Approved for Frequency Control Markets
Scheduled for completion in 2025, the Sopi solar park will have a capacity of 74 MW and an expected annual generation of 75 GWh (75 million kWh), enough to power approximately 22,500 Estonian households. Now, it also actively contributes to frequency stability. The technical integration was carried out in close cooperation with the Estonian transmission system operator Elering and the German company Emsys VPP, a specialist in virtual power plants.
With a capacity of 30 MW for the aFRR (automatic Frequency Restoration Reserve) down-regulation market and a capacity of 45 MW for the mFRR (manual Frequency Restoration Reserve) down-regulation market with, Sopi is the first solar park of its size in the Baltics to be fully approved for both frequency control markets. Sopi thus takes on a pioneering role in integrating photovoltaics into grid-stabilizing markets. This development is seen as a paradigm shift in the role of renewable energy within the power system.
“Renewable energy sources like wind and solar need to play a vital role in ensuring grid stability. Enabling the provision of aFRR and mFRR with our Virtual Power Plant (VPP) in partnership with Eesti Energia represents a major step forward in our dynamically growing presence in the Baltics,” said Timo Buschmann, Head of Key Account Management at Emsys VPP.
Grid Synchronization: Baltic States Take Responsibility for Frequency Control
With the synchronization of the Baltic and continental European electricity networks, Estonia, Latvia, and Lithuania are jointly assuming responsibility for balancing electricity supply and demand in the region. This process is supported by dispatchable power plants operated by Enefit Power in Estonia, renewable energy facilities such as wind and solar parks by Enefit Green in Estonia and Lithuania, and Estonia’s first large-scale battery storage system in Auvere.
In addition, digital solutions like the Emsys VPP Virtual Power Plant enable the diversified generation portfolio of Eesti Energia to actively participate in frequency control markets. Participation in these markets means that renewable energy sources are not only environmentally friendly, but also contribute to grid frequency stability, energy security, and price stability.
The more flexible and fast-responding generating units are available on the market, the fewer expensive reserve capacities are required. This ultimately helps reduce electricity prices. Moreover, it enhances energy security in the Baltic region by increasing the use of local renewable resources, thereby reducing dependence on energy imports.
According to Kristjan Kuhi, Management Board Member of Eesti Energia, this achievement represents a major step toward integrating renewable energy into frequency control markets and strengthening the stability of the Baltic electricity grid. “The prequalification of large-scale renewable energy production units for frequency markets proves that wind and solar power plants can also provide frequency reserves – something that has traditionally been the domain of dispatchable power plants,” Kuhi explained. “ The Sopi Solar Park is part of our Virtual Power Plant, which integrates various production and consumption assets and enables real-time frequency control.”
Source: IWR Online, 24 Jun 2025
