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).


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

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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.

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Grid maps

Maps of our onshore and offshore high-voltage grid.

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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.

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Transparency data

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

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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.

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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.

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First grid connection for offshore wind farms in the eastern section of the North Sea.



  • 130 km long and 576 MW capacity
  • 45 km onshore cable
  • 85 km offshore cable

Grid connection point

  • converterstation Büttel Germany

Status of project

  • online since february 2015

About the project


HelWin1 is a 576 megawatt (MW) direct current (DC) grid connection for offshore wind farms near Helgoland. The length of the subsea cable between the mainland coast and the offshore converter platform HelWin alpha is about 85 kilometers. The grid connection lands at Büsum. From there, the grid connection runs another 45 kilometres via land cable to the new converter station and substation in Büttel.

In 2011, horizontal drillings have been carried out below the dyke and the Kiel Canal in order to pull the land cable into the respective ductworks. Afterwards, the subsea and land cables have been laid. In summer 2013, the offshore converter platform HelWin alpha has been installed offshore. In winter 2014/2015 the remaining installations and test programmes have been carried out on HelWin alpha.

In February 2015, HelWin alpha has been taken into Operation.


Henrike Lau

Pressereferentin - Projektkommunikation Offshore

0049 (0)5132 89-2265

HelWin1 project

130 kilometres of cable for a grid connection with a capacity of 576 MW.

Project downloads

Factsheet HelWin1 (german) (289 KB, pdf, 05/17/2016)

576 MW starker Gleichstrom-Netzanschluss für Windparks auf See nahe Helgoland

Category: Brochures
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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.

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media footage

Your way to our pressfootage about HelWin1