Our key tasks

We are primarily tasked with providing power transmission services, system services and facilitating the energy market. Our core tasks follow from our appointment as grid operator under the Dutch 'Elektriciteitswet' (E-wet) and the German 'Energiewirtschaftsgesetz' (EnWG).


Explore our key tasks


TenneT presents Hub and Spoke concept for large scale wind energy on the North Sea.

Read more
Our grid

TenneT manages the high-voltage grid in the Netherlands and large parts of Germany. TenneT transmits electricity at 110,000 volts (110 kV) and higher. With over 22,500 kilometres of high-voltage lines, we cross borders and connect countries.

Explore our grid

Grid maps

Maps of our onshore and offshore high-voltage grid.

To grid maps
Electricity market

The energy sector is developing rapidly. The process of European market integration began some years ago. Its purpose is to create a single European market that enables market parties to trade gas and electricity across national borders easily and efficiently.

Explore the electricity market

Transparency data

We provide transparency data on our operations on our Dutch and German transparency page and on ENTSO-E. 

To transparency pages

Our vision is to be one of the most transparent Transmission System Operators (TSO) in Europe and thereby creating value for society. In this Energy Insights section we present selected energy related topics and show data, information and valuable insights. 


Energy transition

Wind turbines and solar panels are the physical signs of consumers’ growing desire for clean, renewable energy.

Read more

TenneT is a leading European electricity transmission system operator (TSO), with activities in the Netherlands and in Germany. We strive to ensure a reliable and uninterrupted supply of electricity in our high-voltage grid for some 41 million people.

Explore our company

We are TenneT

Meet us


160 kilometer long subsea cable for the connection of wind farms off the coast of Sylt



  • 205 km long and 864 MW capacity
  • 45 km onshore cable
  • 160 km offshore cable

Grid connection point

  • converterstation Büttel Germany

Status of project

  • online since april 2015

About the project


SylWin1 is a 864 megawatt (MW) grid connection in DC technology. In order to connect the wind farms DanTysk, Sandbank and Butendiek in the Eastern North Sea region, it is necessary to bridge a distance of about 205 kilometres to the transmission system.

The wind farms are located up to 70 kilometres west of Sylt. Via SylWin1 they can feed in large quantities of wind power into the German power grid. On the offshore converter platform SylWin alpha the three-phase alternating current generated by the connected offshore wind farms is converted into DC power. The grid connection comprises about 160 kilometres of subsea cable and 45 kilometers of land cable. The subsea cable route in the coastal waters as well as the land cable are running parallel to the line for the projects HelWin1 and HelWin2.

In the onshore converter station in Büttel the DC power is re-converted into AC power and fed into the transmission system through the local substation. The jacket, the subconstruction of the offshore converter station, was put up in April 2014. In summer 2014, the further erection of the converter platform SylWin alpha took place with the placing of the topside. The converter station as well as the laying of the DC cables is completed. The laying of the AC cables to the offshore wind farms Dan Tysk, Butendiek and Sandbank and the appropriate cable entry works have been completed.

The grid connection has been taken into operation on 15 April 2015.


Henrike Lau

Pressereferentin - Projektkommunikation Offshore

0049 (0)5132 89-2265

SylWin1 project

205 km long and 864 MW strong DC-Connection (HGÜ)

Project downloads

Fastsheet SylWin1 (german) (288 KB, pdf, 05/19/2016)

160 Kilometer langes Seekabel zum Anschluss von Windparks vor Sylt

Category: Brochures
Fastsheet SylWin1 (german) Download Download
Die Naturschutzprojekte von TenneT (german) (785 KB, pdf, 08/02/2016)

Aufwertung der Lebensräume von zahlreichen Pflanzen- und Tierarten

Category: Brochures
Die Naturschutzprojekte von TenneT (german) Download Download

Also interesting

TenneT Offshore brochure

"Energie von See an Land" brochure about TenneT offshore projects and technology (german only)

Offshore projects in Germany

Our other german offshore projects.

Read more

Media footage

Your way to our pressfootage about SylWin1.

Read more