Iberdrola has announced the completion of the installation of the offshore substation topside (OSS) of its 476MW Baltic Eagle offshore wind farm in the German waters of the Baltic Sea.

The installation has been executed by the Netherlands-based Heerema Marine Contractors by utilising the Thialf installation vessel.

Iberdrola and transmission system operator 50Hertz forged an agreement to collaborate on the construction, installation, and commissioning of the OSS for the German offshore wind farm in May 2021.

The OSS’ role is to collect the clean energy produced by the wind turbines and convert the supply voltage before feeding it into the onshore power grid at the Lubmin grid interconnection point.

It is expected to collect and export the entire electricity produced, which is anticipated to be around 1.9TWh per year.

The substation has a foundation and a topside that features a closed multi-storey module of five decks for housing the transformers and electrical equipment.

Iberdrola Deutschland offshore division managing director and deputy CEO Iris Stempfle said: “The offshore substation is a key piece of technology for supplying sustainable energy to hundreds of thousands of households and for the decarbonisation of German industry. We are very pleased to have achieved this central milestone in close cooperation with 50Hertz as planned.”

With the completion of the substation installation, Iberdrola expects to begin the offshore phase to prepare the OSS for energisation. Following the energisation, installation of monopiles will take place to which the wind turbines are attached with transition pieces.

Once connected to the grid, the clean energy produced by the wind turbines will be transmitted to the offshore substation through inter-array cables.

The substation will then transform it from 66kV to 220kV and transmit through two high voltage subsea cables across a distance of 90km to the Lubmin landing point into the 50Hertz transmission grid.

Iberdrola expects to commence operations at the Baltic Eagle offshore wind farm in 2024.