Battery Energy Storage System co-operating with Electric Boiler

Complete 7 MW / 7.4 MWh BESS system delivery

At the core of the project are two Merus^® Power Conversion Systems (PCS), designed and manufactured in Finland by Merus Power. Engineered for demanding grid applications, the PCS units provide fast dynamic response, precise power control, and reliable performance in electricity markets.

The delivery forms a 7 MW / 7.4 MWh lithium iron phosphate (LFP) Battery Energy Storage System (BESS) consisting of two 20-foot battery containers with a one-hour rating. The system also includes a 7 MVA PCS transformer and a Merus-developed EMS controller, creating a fully integrated and optimized solution built for high-performance grid support.

Finnish power electronics expertise ensuring reliability

Built on strong expertise in power electronics and grid solutions, Merus Power ensures seamless integration between batteries, PCS, transformer, and control systems.

The entire system is engineered and rated to operate in ambient temperatures down to –40°C, which is a critical requirement in Nordic conditions. This extreme-weather capability ensures high availability and dependable operation even during the coldest winter periods, when grid stability is most essential.

The architecture is optimized for efficiency, availability, and long-term performance, ensuring consistent value creation in electricity markets.

Sector coupling: Intelligent aggregation of BESS and Electric Boiler

A key differentiator of this project is the coordinated aggregation of the BESS and an Electric Boiler (EB). While a stand-alone battery is classified as a Limited Energy Reservoir (LER) with bid-size limitations in FCR markets, and a standalone EB’s regulation capacity is dependent on its operating power setpoint, the combined system significantly reduces these constraints. In other words, the available capacity of the electric boiler depends on the heat demand of the district heating network.

Individually, the Electric Boiler’s upward and downward regulation capability is inherently asymmetric and limited by its current operating level. Through intelligent aggregation with the BESS, symmetric reserve delivery can be achieved more effectively and with greater operational flexibility.

By leveraging the large thermal energy capacity of the boiler alongside battery storage, the solution increases available bid capacity and mitigates the impact of LER-related limitations. Intelligent EMS control optimizes state-of-charge management, while the Electric Boiler covers most of the energy activation, reducing battery degradation.

This integrated control strategy maximizes asset utilization, enhances operational flexibility, and delivers a true “1 + 1 = 3” outcome, combining electrical and thermal resources into a higher-performing, revenue-optimized energy solution that strengthens national grid stability.