In Q1 2026, offshore construction for BorWin6 commenced with the installation of the BorWin kappa converter platform jacket at the project site in the German North Sea (Cluster 7). The 5,461-tonne jacket foundation, fabricated at McDermott's Jebel Ali yard in the UAE, was loaded out by Mammoet in February 2026 and sailed to the installation site. Per Heerema/Mammoet Q1 2026 social media updates (including Hallam Knight's LinkedIn posts ~March 2026), the jacket was successfully installed offshore with pin piles in place, marking the first offshore works at the project site. Topside float-over is expected later in 2026. This is the genuine offshore_construction_start for BorWin6 — distinct from the earlier factory fabrication milestones (first steel cut July 2023, topside staging Jan 2025, jacket loadout Feb 2026) which are recorded as manufacturing_update events.
By 6 February 2026, a major fabrication milestone for BorWin6 was reached at Jebel Ali, UAE, where Mammoet completed the transport, loadout, and mooring of the 5,461‑tonne offshore jacket foundation that will support the BorWin kappa offshore converter platform for TenneT’s 980 MW BorWin6 HVDC grid connection in the German North Sea.
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BorWin6 is a 980 MW high-voltage direct current (HVDC) offshore grid connection developed and owned by the transmission system operator TenneT to link North Sea offshore wind to the German onshore grid. The system collects three‑phase AC from offshore wind turbines via 66 kV inter‑array connectio...
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Social media and case study material from OEG Energy Group, dated 18 December 2025, describe a completed pre-lay grapnel run (PLGR) campaign on the nearshore cable system for TenneT Germany's BorWin6 project on behalf of Nexans. The PLGR is a debris clearance step that typically follows UXO survey and clearance work and is carried out once the route has been prepared. Combined with personnel CVs indicating UXO survey work in late 2023, this implies that the UXO survey, identification and clearance campaign for BorWin6's export cable route was complete by late 2025, somewhat later than the originally projected 31 October 2024 date.
In 2025, Mammoet completed moving the BorWin6 offshore HVDC converter platform topside module from its construction position to an interim staging area at the fabrication yard in Jebel Ali, United Arab Emirates, marking an earlier fabrication and handling milestone for the platform topside.
On 14 August 2024, TenneT held the formal groundbreaking ceremony (Spatenstich) for the BorWin6 onshore converter station at Büttel in Schleswig-Holstein, Germany, marking the official start of onshore construction works for the land-side of the 980 MW 320 kV HVDC grid connection. The ceremony was hosted on the grounds of the existing Umspannwerk Büttel, where three HVDC converters are already in operation and the BorWin6 converter will be built as the fourth adjacent converter, together with the EPC consortium of McDermott International (lead contractor), GEIRI, and C-EPRI Electric Power Engineering, and attended by regional political and industry representatives. The ceremony is the canonical starting signal for the Landkonverter build; substantive civil works (excavation, piling, foundations) are understood to have ramped up in the weeks following, with the onshore converter targeted for readiness in 2027 ahead of the project's planned commercial operation in October 2027. Onshore cable trenching along the 45 km Büsum–Büttel route is a separate workstream being delivered by Friedrich Vorwerk Group / Bohlen & Doyen for Nexans, continuing into 2026.
BNetzA confirmed BorWin6 in Netzentwicklungsplan (NEP) 2037/2045 (2023) on 1 March 2024. This confirmation under §12c EnWG creates the legal basis for the responsible TSO to plan, procure, and construct the offshore grid connection system.
BNetzA confirmed the Netzentwicklungsplan Strom 2037/2045 (2023 edition) on 1 March 2024 under section 12c of the German Energy Industry Act (EnWG). This confirmation creates the legal basis and obligation for the responsible TSO to plan, procure, and construct this offshore grid connection system. For regulated German TSO offshore grid connections, the BNetzA NEP confirmation functions as the de facto Final Investment Decision: unlike merchant or developer-led projects that require a separate board-level investment decision and financial close, the NEP confirmation simultaneously authorises and obligates the TSO to invest. Costs are recovered through the offshore grid levy (Offshore-Netzumlage). The NEP 2037/2045 (2023) schedules 25,980 MW of offshore transmission capacity across 16 grid connection systems for commissioning between 2026 and 2032.
LinkedIn profile of an Ocean Infinity survey professional lists work on the "TenneT-BorWin6 UXO survey, German Bight" with offshore UXO survey activities dated November–December 2023. This indicates that the marine UXO survey campaign for BorWin6 started offshore in November 2023, later than the previously projected March 2023 date.
On 6 July 2023, submarine cable contractor Asso.subsea signed a contract with Nexans to transport, install, and protect the nearshore section of the 320 kV DC connection for TenneT’s BorWin6 HVDC project, including work in very shallow waters and assistance on the Waddenzee work package using the DP2 cable‑laying vessel Atalanti and its Hydroplough burial tool, with marine operations scheduled for 2025.
McDermott held first steel-cutting ceremony at Jebel Ali fabrication yard in Dubai for BorWin6 980 MW HVDC converter platform.
On 6 July 2022, Dutch‑German grid operator TenneT awarded Nexans the contract for production and laying of the approximately 235‑kilometre cable system for the BorWin6 offshore grid connection, securing the supplier and installer for the 320 kV HVDC export cables that will transmit 980 MW from the German North Sea to the mainland.
On 30 June 2022, TenneT began a tendering process to procure a contractor for marine geophysical UXO survey, identification, and clearance along the BorWin6 HVDC export cable route (with BorWin5 as an option), requiring full survey, disposal activities, and final route and target clearance certification under Section 7 of the German Explosive Act in the German Bight and EEZ.
On 15 February 2022, TenneT awarded a consortium of McDermott and GEIRI/C‑EPRI a contract for the offshore and onshore converter stations for the 980 MW BorWin6 offshore grid connection, covering engineering, procurement, fabrication, transport, installation and commissioning of the BorWin kappa offshore topside and jacket, as well as EPC and commissioning of the onshore converter station and HVDC system.
By February 2022, TenneT had increased the planned connection capacity of the BorWin6 offshore grid link from 930 MW to 980 MW during technical planning, enhancing the amount of offshore wind power that the 320 kV HVDC system will be able to transmit to the German grid.
In June 2021, TenneT launched the export cable tender for the BorWin6 offshore grid connection, seeking a contractor to design, supply, install, and commission the export cable system for the approximately 235‑kilometre route between the BorWin kappa offshore converter platform and the onshore station at Büttel, with contract award indicated for the following summer.
In December 2020, transmission system operator TenneT issued a tender notice for the design, manufacture, installation, and commissioning of the offshore and onshore converter stations for the BorWin6 HVDC grid link in the German North Sea, formally opening procurement for this key system component.
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