Dong will be providing operation and maintenance services to Gunfleet Sands under a long-term arrangement. The two firms have also agreed a long-term purchase agreement for the power production and green certificates arising from Marubeni's share of the project.
The acquisition does not include a stake in the transmission assets, which have been sold as part of the general tender process initiated by the UK regulator, Ofgem.
Marubeni has a worldwide renewable-energy portfolio, dominated by onshore wind, with a total capacity of 450MW. However, this transaction represents the first investment by any Japanese company in an offshore wind project.
The firm's other main commitment in the offshore wind sector to date has been as part of the Google-led consortium developing the Atlantic Grid Connection 6GW offshore transmission line, planned to run from New Jersey to Norfolk, Virginia.