The largest battery storage deal with a privately owned company in the Baltics, with Estonia in the pipeline, reaching 790 MWh in total.
Sunly, one of the Baltics' fastest-growing renewable energy platforms, and Rolls-Royce Power Systems have signed contracts to build four utility-scale battery energy storage systems (BESS) in Latvia with a combined capacity of 490 MWh. The agreement was announced at the opening of Sunly's new solar park in Valmiera, which is set to become one of Latvia's first hybrid energy parks. The Valmiera battery system will be commissioned in Q1 2027, with the remaining three sites following through 2027.
One-stop-shop Solution
Sunly selected Rolls-Royce to deliver the entire project under one roof, from design and equipment supply through to construction and handover. Having a single partner responsible for all four sites gives Sunly the confidence that the systems will be delivered on time, to specification, and ready to operate from day one.
“Our strength lies in supplying integrated, high-performance battery energy storage systems. As main contractor, we provide a single point of responsibility towards our customers, which helps them reduce risks and complexity, secure bankable performance and maximize long-term asset value”, said Andreas Görtz, President Business Unit Mobile & Sustainable at Rolls-Royce Power Systems.
Rolls-Royce will use their proven mtu EnergyPack and software platform, which manages when to store and when to release energy, keeping the grid stable and supply and demand in balance.
A European Partner for Critical Infrastructure
Following the Baltic states' disconnection from the Russian electricity grid and synchronisation with the European network, balancing markets have opened to all market participants. Battery storage is the most effective way to meet the growing need to maintain grid frequency and stability.
"As a provider of vital services, we must meet strict cybersecurity requirements. For us it was essential to find a European partner who could take full responsibility for the entire project and had already proven their capability in Latvia. Rolls-Royce had delivered for the Latvian grid operator AST in 2025 and the same team will now build all four of our sites,"says Priit Lepasepp, CEO of Sunly.
“Together with Sunly, we are delivering large-scale battery storage systems that will play a critical role in strengthening grid stability and energy security in the Baltics. By providing fast, flexible and reliable capacity, our BESS solutions support the integration of renewable energy, improve system resilience and contribute to a more secure and sustainable energy infrastructure,” said Andreas Görtz, President Business Unit Mobile & Sustainable at Rolls-Royce Power Systems.
Looking Ahead: a Baltic-Wide Partnership
Latvia is the first chapter of a broader collaboration.Sunly and Rolls-Royce have signed a Memorandum of Understanding to extend the partnership to Estonia with an additional 300 MWh project at Risti, bringing the total pipeline to approximately 790 MWh across the Baltic states.
"Our aim is to build an energy system that works for people, not just when the sun shines. By combining solar generation and battery storage, we can produce energy when conditions are right and deliver it when it is needed, making renewable energy more reliable and less dependent on weather conditions. Co-locating generation, storage, and consumers like data centres in one place is how renewable energy becomes truly efficient. Latvia is the start. Estonia is next. And we have the right partner to get there," says Priit Lepasepp, CEO of Sunly.
Sunly was advised by Sorainen and Rolls-Royce by Eversheds Sutherland as legal counsel on the transaction.