The Gwynt y Môr wind farm is being built by RWE npower renewables and comprises of 160 wind turbines
The project is being funded by RWE Innogy, in partnership with Stadtwerke München GmbH and Siemens.
Balfour Beatty CEO, Andrew McNaughton, said: “Gwynt y Môr is a significant step in the development of our investment business in non-PPP infrastructure markets, as well as our wider strategy of developing our delivery capability in the offshore renewables industry.
“It firmly places Balfour Beatty in a leading position within the fast growing and potentially very large offshore transmission markets.”