Vattenfall and Return sign deal for 800 MWh battery park in Groningen

Vattenfall and energy storage company Return have signed a long-term agreement for Sirius, a large-scale battery park in the province of Groningen, Netherlands. The project, located near Winschoten, features a capacity of 200 megawatts and a total storage capacity of 800 megawatt-hours.

With an estimated investment of approximately 180 million euros, Sirius is one of the largest battery storage projects currently under development in the Netherlands. Under the tolling agreement, Vattenfall will have access to the full storage capacity, allowing the company to manage fluctuations in wind and solar energy production and support TenneT in maintaining grid stability.

The facility will connect to the TenneT substation in Meeden using a Time-Dependent Transmission Rights (TDTR) model. This approach allows the battery to synchronize its charging and discharging cycles with available grid capacity, optimizing existing infrastructure and helping to mitigate grid congestion. Commercial operations are scheduled to begin in the fourth quarter of 2027.

Financing for the project is part of a broader 400 million euro portfolio financing provided by a consortium of five banks: ING, NatWest, Deutsche Bank, ABN AMRO, and Rabobank. Huawei will supply the batteries, while Hanab and Omexom serve as construction partners.