The deal is for 80 SWT-3.6-120 turbines. They will go to the Meerwind East and West projects, located 23km north of Heligoland.
Siemens will also be responsible for installing the Meerwind turbines, which it aims to complete by 2013. On completion, the project will cover 42 square kilometres in water depths of 22 to 26 metres.
WindMW is owned by private-equity firm Blackstone and developer Windland Energieerzeugungs.
This is Siemens' sixth German offshore project. The others include EnBW Baltic 1 (48.3MW), EnBW Baltic 2 (288MW), Borkum Riffgat (108MW), Dan-Tysk (288MW) and Borkum Riffgrund 1 (320MW).