DolWin6
OperationalOffshore GridDE900 MW320 kV90 km2023
Basic information
9 fieldsAlso Known As
DolWin 6 · NOR-3-3
Status
operational
Capacity
900 MW
Owners
Project Company
Type
offshore grid
Transmission Model
TSO Build & Own
Expected Life
30 years
Website
Supply Chain (17)
Project Timeline (11)
~Mar 2026System TestingStale
For the DolWin6 network connection, Jan De Nul and Hellenic Cables plan to carry out the final connection and testing works in spring 2026 on three 155 kV HVAC grid connection cables between the Nordseecluster 1 and 2 offshore wind farms and the DolWin kappa platform, following completion of the Nordseecluster offshore substations.
15 Dec 2025Cable Installation Complete
Jan De Nul, together with partner Hellenic Cables, completed the 2025 transport and installation campaign for three 155 kV HVAC grid connection cables totalling 37 km that link the Nordseecluster 1 and 2 offshore wind farm sites to TenneT’s DolWin kappa offshore converter platform for the DolWin6 project. Using the cable-laying vessel Isaac Newton, the multi-purpose vessel Adhémar de Saint-Venant, and the rock installation vessel Simon Stevin, the contractors installed, buried, and protected the cables, which will transmit almost 660 MW of power from Nordseecluster 1 and 2 into the DolWin6 HVDC grid connection, with the campaign reported as finished in mid-December 2025.
11 Nov 2023Cable Installation Complete
Pfisterer completed installation and high-voltage testing of a 155 kV Feltoflex bridge cable between the DolWin kappa offshore converter platform (part of TenneT’s 900 MW DolWin6 grid connection) and the existing DolWin beta platform in the German North Sea. Around 2 km of cable were pulled between the two platforms and jointed with CONNEX plug connectors and epoxy resin joints, creating a redundant inter-platform link to enhance network security, with final offshore installation and testing reported in a 11 November 2023 press release.
Sept 2023Commercial Operations Full Power
DolWin6 grid connection system commissioned and operational.
26 Sept 2023System Testing
In the weeks leading up to commissioning of DolWin6, Siemens Energy conducted trial operation of the 900 MW HVDC offshore grid connection for TenneT. These several weeks of system-level testing of the DolWin kappa offshore converter platform, subsea and land cables, and the onshore converter infrastructure preceded the handover of the connection for regular operation.
4 Sept 2022Construction Other
The DolWin kappa offshore converter station for TenneT’s 900 MW DolWin6 grid connection was installed at its offshore site in the German North Sea. After transport from Cádiz via Rotterdam on Allseas’ barge Iron Lady and transfer to the construction vessel Pioneering Spirit, Allseas completed a 12-day offshore campaign by 4 September 2022, installing the approximately 5,000-tonne jacket foundation and 11,000-tonne topsides and driving ten piles up to 68 metres into the seabed about 45 kilometres off the coast.
Mar 2022Manufacturing Update
Within TenneT’s DolWin6 project, fabrication and high-voltage outfitting of the DolWin kappa offshore converter platform in Cádiz, Spain, were completed and the platform was formally handed over in March 2022, following final high-voltage testing of the 155 kV and 362 kV systems and installation of PFISTERER’s CONNEX high-voltage fittings and cabling.
3 Jul 2019Tyndp Listed
Authority: ENTSO-E · Licence: Ten-Year Network Development Plan (TYNDP) project listing
By July 2019, the 900 MW DolWin 6 offshore DC grid connection in Germany, owned by TenneT, was listed in a WindEurope policy paper drawing on ENTSO-E’s Ten-Year Network Development Plan data, which detailed DolWin 6 as a DC transmission project with an estimated CAPEX of €1,180 million and an average distance of 90 km to shore.
2017Other Permit Awarded
Licence: Transmission asset licence (type unspecified)
According to WindEurope’s offshore grid cost database, the DolWin6 offshore HVDC grid connection in Germany is shown as having its transmission asset licensed in 2017, indicating that the necessary regulatory authorisation to develop and/or operate the DolWin6 platform and associated grid connection was in place by that year.
17 Jul 2017Converter Supplier Selected
On 17 July 2017, TenneT awarded Siemens a contract to build and install the 900 MW DolWin6 offshore grid hub in the German North Sea, including the HVDC converter infrastructure that will connect the offshore wind farms to the onshore grid at Emden/Ost. Siemens will deploy its direct current compact switchgear technology, enabling a more compact 900 MW platform compared to previous designs.