Sumitomo Corporation, through Summit Transition Partners (STP), has agreed to invest in multiple large-scale battery energy storage system (BESS) projects in the UK. The projects are being developed by Gresham House Energy Storage Fund plc. Additionally, Sumitomo Corporation has also entered into a battery storage partnership with Gresham House Limited.

The portfolio includes five utility-scale BESS projects with a combined planned capacity of around 694 MW. Construction of the first three projects, totaling 397 MW, is expected to commence within the current fiscal year. STP has also secured exclusivity rights for the remaining two projects with a combined capacity of 297 MW.

In May 2026, Sumitomo Corporation and its partners, including Ocean Winds, Allianz Global Investors, Caisse des Dépôts et Consignations, and Vendée Energie, commenced commercial operations of the 500 MW Noirmoutier Offshore Wind Farm in France. The project began construction in April 2023 and is expected to generate enough electricity to power around 800,000 people annually. The project will operate for approximately 25 years, with electricity supplied under a long-term fixed-price agreement with Électricité de France.