Sofia Offshore Wind Farm, North Sea, United Kingdom
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Sofia Offshore Wind Farm

Sofia offshore wind farm is a 1.4GW wind farm being developed offshore UK. The wind farm will supply power to approximately 1.2 million UK households at a rate of 5.4 terawatt-hours per annum.

Project Type

Offshore wind farm


Offshore UK, North Sea



Estimated Investment

£3bn ($3.7bn)


Sofia offshore wind farm is a 1.4GW wind farm being developed offshore UK. The wind farm will supply power to approximately 1.2 million UK households at a rate of 5.4 terawatt-hours per annum, contributing nearly half of the annual electricity requirements of north-eastern UK.

The project is being developed with an estimated investment of £3bn ($3.7bn). It is 100% owned by Innogy and is the largest in its development portfolio.

Onshore construction for the project is expected to begin in early 2021, while offshore work will commence in 2023. The wind farm is expected to begin operations in 2024.

Sofia offshore wind farm location

Sofia offshore wind farm will be located on Dogger Bank, 195km off the UK coast in the central North Sea.

The 593km² site provides excellent wind conditions with relatively low water depths of 21m to 36m.

Sofia wind farm details

Sofia wind farm will include 100 turbines, an offshore converter station, onshore electrical infrastructure and inter-array and export cables.

The wind farm will employ Siemens Gamesa Renewable Energy’s SG 14-222 DD offshore wind turbines. The 14MW and 262m-tall turbine provides 25% more power than its next largest model.

"The project is being developed with an estimated investment of £3bn ($3.7bn)."

The turbine’s 108m-long carbon and fibreglass IntegralBlade is cast in one piece, using Siemens Gamesa’s blade technologies. Its 222m-diameter rotor sweeps an area of 39,000m², equivalent to approximately 5.5 standard football pitches.

The SG 14-222 turbine uses the Siemens Gamesa Direct Drive technology, which provides operational stability and high availability with minimal associated costs and risks.

Each turbine will be installed on a monopile and transition piece foundation where the monopile is securely driven into the seabed.

Power transmission details

The power will be transported from the turbines to the wind farm’s offshore converter platform by a network of 370km of inter-array cables. The electricity is then converted from 66kV alternating current (AC) to 320kV direct current (DC).

The electricity will be transported to the shore via two 220km export cables, which will form a single high-voltage direct-current circuit and make landfall between Redcar and Marske-by-the-Sea.

Two 7km DC onshore cables, forming a single high-voltage direct-current circuit will then transport the electricity to an onshore converter station to be constructed near Lazenby. Thereafter, the power is transmitted to the existing national grid substation at Lackenby via six 2km AC cables.

Sofia wind farm construction details

The wind farm site was undergoing the final phase of a six-month pre-construction site investigation in June 2020.

Site investigation will be completed by a multi-purpose vessel called Despina and Fugro Scout survey vessel. Coastal survey vessels Fugro Seeker and Fugro Mercator will carry out geophysical surveys along the nearshore export cable corridor, off the coast of Redcar in Teesside.

Fugro Pioneer and Despina already concluded export cable route surveys. Fugro Seeker and Fugro Mercator will gather data to inform the design of the export cable and the installation methodology. The vessels will complete the works by July 2020 with the support of a local guard vessel.

The information from the investigation will be used to calibrate the array design and verify the installation of the turbine foundations, offshore converter platform and the array cables.

A 29m-long jack-up vessel named Haven Seariser 2 is also employed for a six-month offshore site investigation in the nearshore area between Redcar and Marske-by-the-Sea.

The boreholes from the investigation coupled with earlier surveys will collect data to determine the final design and installation methodology for the landfall location of the main transmission cable.

The full site investigation will be completed by August 2020.

Contractors involved

Siemens Gamesa was selected to manufacture, install and commission the turbines for the wind farm. The conditional order also includes a comprehensive service and maintenance contract.

Fugro is providing geophysical and geotechnical services along with works on the wind farm array.

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