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DolWin1 is the first offshore project that TenneT has realised off the bay of Dollart - in the so-called DolWin cluster. Since 2015, up to 800 megawatts (MW) of electricity have been transported over a distance of 165 kilometres through the North Sea and across the mainland using the powerful DolWin1 high-voltage direct current connection.

Lower Saxony, North Sea
  • DolWin1

About the project

1165 kilometre long and 800 megawatt strong direct current connection


The network connection runs 75 kilometres at sea and another 90 kilometres over land to the converter station in Dörpen West (Heede). Here, the wind power generated at sea is converted from direct current into three-phase alternating current and fed into the grid.

Connecting concept

The electricity generated at sea is collected in the wind farm's own transformer station. From there the energy is transported to TenneT’s offshore converter platform via a 155 kilovolts three-phase alternating current (AC) cables. The conversion of AC to direct current (DC) takes place in the offshore converter station. The electricity is then transported by submarine and underground cable to the corresponding land station. Here, the electricity is converted back into AC and fed into the TenneT extra-high voltage grid.


  • DolWin1 Seekabelverlegung Lewek

    Submarine cables are polymer sheathed and consist of a copper conductor and an insulation made of cross-linked polyethylene.

  • DolWin1 cable laying

    The cable laying vessel installs several kilometres of submarine cable in the North Sea. Usually, the submarine cable is laid as a whole or in a few sections.

  • DolWin1 convertion Dörpen West

    In Dörpen/West, the direct current is converted back into three-phase alternating current.

  • DolWin1 convertion Dörpen West

    The land station of DolWin1 is located in Dörpen/West.

  • C

    With the help of a so-called vibrating sword, the cable are laid in the Wadden Sea.

  • DolWin1 Anlandung Norderney

    The cable route of DolWin1 runs across the East Frisian island of Norderney.

  • DolWin alpha Installation

    The DolWin alpha offshore platform has a length of 57 metres above the sea surface.

  • DolWin alpha Installation

    The substructure of the DolWin alpha offshore platform was installed in 2012, followed by the installation of the upper part in 2013. In the process, the platform was placed on its substructure using the world's largest floating crane.



cornelia junge.jpg

Cornelia Junge

Spokesperson - Project Communication Offshore

Further information