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.
Project Details in Latvia
Latvian Solar Parks by Sunly
- Valmiera (Matīši): 54 MW
- Dagda: 90 MW
- Barkava: 81 MW
- Zirni (Saldus): 104 MW
Phase 1 with Rolls-Royce
- Barkava: 59.4 MW / 120 MWh, commissioning Q1 2027
- Valmiera: 40.5 MW / 80 MWh, commissioning Q1 2027
Phase 2 with Rolls-Royce
- Zirni: 99.9 MW / 200 MWh, commissioning Q2 2027
- Dagda: 45.9 MW / 90 MWh, commissioning Q2 2027
Total: approximately 246 MW / 490 MWh
About Sunly
Sunly is an integrated energy infrastructure platform that combines renewable generation, storage and large-scale electricity demand, turning clean power into a competitive advantage for electrified industry and digital infrastructure. Sunly operates in the Baltics and Poland. Sunly employs nearly 200 people and is backed by investors including Mirova, Vardar, EBRD and junior and senior lenders Rivage Investments, CIP, KLP, EIB, EBRD, SEB, mBank, Luminor and Swedbank.
About Rolls-Royce Power Systems
Rolls-Royce Power Systems is headquartered in southern Germany and employs around 11,000 people. The product portfolio includes mtu-brand high-speed engines and propulsion systems for ships, heavy land, rail and defence vehicles and for the oil and gas industry. The portfolio also includes diesel and gas systems and battery solutions for mission critical, standby and continuous power, combined generation of heat and power, and microgrids.
Rolls-Royce supplies turnkey large battery solutions consisting of modular units for capacity and power that can be flexibly configured to any size. The components of the mtu EnergyPack include integrated battery cabinets and the intelligent mtu EnergetIQ control system. They are primarily used for grid services, energy trading and the integration of renewable energies. Rolls-Royce Power Systems has now delivered mtu battery storage solutions for over 200 projects worldwide.
