The order is for 10 MM82 2.05MW turbines. They will be installed on a project near Bradwell-on-Sea, Essex in the latter half of the year. It has been in development since 2005.
The land earmarked for the wind farm is currently occupied by a nuclear power station that closed in 2002. The station's grid connection is likely to be used by the project.
Speaking about the deal, Michael Williams, project manager from RWE npower renewables, said: "RWE Npower renewables are now finalising contracts for the associated Civil and Electrical Balance of Plant works.
"We aim to start construction of the wind farm before Easter 2012, which is likely to present opportunities for economic benefit and employment in the region."