The two 2,900-tonne substations, comprising topsides and jacket foundations, were built by a consortium of Engie Fabricom and Iemants and were shipped out from Hoboken, Belgium, in March.
Located next to the 367.2MW Walney 1 & 2 offshore wind farms off Cumbria, Walney Extension will be the largest wind farm in the world when built and commissioned in 2019.
The wind farm will consist of 40 8MW MHI Vestas and 47 7MW Siemens wind turbines.