Sunly successfully passed Elering’s pre-qualification and connected Estonia’s first large battery storage system to the manual Frequency Restoration Reserve (mFRR), a prerequisite for joining the pan-European MARI (Manually Activated Reserves Initiative) system. The battery storage system at the Pikkori solar park near Kilingi-Nõmme can deliver 1.7 MW to the grid and has a nominal capacity of 2 MWh. It is the largest battery storage system currently operating in Estonia.
While renewable energy developments have gained momentum, less attention has been paid to storage as an important system component. Without storage capacity, the future electricity market will remain volatile. Supply and price fluctuations do not please anyone and will not support a sustainable business environment. The importance of storage will increase further upon decoupling the Baltic systems from the Russian grid and joining the continental European frequency area in 2025. A prerequisite for connecting to the area is the creation of frequency reserves, which will step in during longer fluctuations in the grid that cannot be covered by the usual energy supply.
Batteries are not the sole reserve solution, but have clear advantages both today and in the future. Firstly, this technology is the most responsive in terms of reserve operation. While the mFRR market assumes a 12.5 minute response time, the Sunly battery can be activated within a few seconds. This speed meets the needs of more demanding markets, which can be joined after decoupling from the Russian grid. For example, aFRR requires a 30-second response, while FCR is the most stringent with 5 seconds. Elering has already begun cooperation with the Finnish grid operator Fingrid to test the faster markets. Sunly is prepared to contribute to this and other pilot projects at the earliest opportunity, so as to support the smoothest possible transition to the European frequency area. Ultimately, the security of the future energy market will be determined the ability to respond quickly and to sell cheaply stored energy at times of peak demand. Batteries are good for both. Given that the sustainability of frequency management is ensured by speed and year-round responsiveness, battery solutions deserve much more focus and commitment.
Estonia has set a target to reach 100% renewable energy consumption by 2030. This is a major and realistic milestone, but also necessitates the creation of an energy system that is sustainable in the long term. To achieve this, we need to support innovation and new technologies, thereby contributing to continuous system development based on smart processes, with renewables and storage as clear priorities.
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