The development is owned by RWE Innogy (60%), Stadtwerke München (30%) and Siemens (10%). Installation of the 160 3.6MW Siemens turbines will begin late next year. These are expected to start producing electricity by 2013. Overall completion is set for 2014.
The project will cost €2billion with €1.2billion of this going to Siemens, which has a five-year O&M contract. The budget also includes grid connections and two transformer platforms.
Permission to build Gwynt n Môr was agreed in late 2008. The project will significantly aid Wales ambition to supply a third of its electricity through wind.
RWE's go-ahead for the project follows its decision to pull out of its partnership with SeaEnergy Renewables (SERL) to develop Scotland's 905MW Inch Cape offshore wind farm. The company said at the time that it needed to rationalise its renewables committments.
Speaking about the Gwynt n Môr project, Prof. Fritz Vahrenholt, CEO of RWE Innogy, said: "In 2008 we started making RWE greener. With an output of almost 580 MW and an annual saving in CO2 production of around 1.7 million tonnes, Gwynt y Môr will contribute significantly to this. This is the fifth offshore wind farm which RWE is not only developing but also building - a balance to be proud of."
Gwynt n Môr will the second biggest wind farm in the world, however it falls some way short of the 1GW London Array project that is currently being build in the Thames Estuary.