Trianel and EWE have formed a joint venture (JV) to develop the 200MW phase two of the Trianel wind farm Borkum (TWB II) in the German North Sea.
Phase two of the offshore wind farm will require an investment of about €800m, with the offshore substation already in place.
The on-site transformer platform, which secured a licence from the German Federal Maritime and Hydrographic Agency, is now ready.
EWE will have a 40% share in the development of the project and the companies expect a final investment decision in 2016.
Located 45km off the island of Borkum, the €1bn first phase of the offshore wind farm that was inaugurated last month reached full commercial operation in July.
Phase one, with 40 Areva / Adwen turbines, will generate more than 800GWh of clean energy a year; sufficient to power 200,000 homes.
Areva started installing the wind turbines at the first phase of Trianel wind farm Borkum in September 2013.
During the initial expansion, Trianel created conditions to increase the project’s capacity to 400MW.
EWE chief technology officer Ines Kolmsee said: "EWE can call upon its expertise from the development and operation of the first German offshore wind farm, alpha ventus, and the first commercial offshore wind farm, Riffgat.
"Trianel will contribute the knowledge it gained during the development of the Trianel wind farm Borkum, the first municipal offshore wind farm."
Trianel management spokesman Sven Becker said: "The joint venture with EWE provides the foundation for the planned decision to build during the next year."