SK Oceanplant has secured an approximately $110.7 million contract from Seatrium to supply the jacket foundation and piles for TenneT’s BalWin5 high-voltage direct current offshore converter platform in the German North Sea.
The agreement, valued at around EUR 96 million, covers construction engineering, procurement, fabrication and load-out. SK Oceanplant will deliver one jacket foundation and 20 piles for the offshore substation.
The jacket will weigh approximately 15,000 tonnes. SK Oceanplant said the contract is the first full jacket supply agreement awarded to a Korean company for a European HVDC offshore substation.
SK Oceanplant entered the European offshore wind market through the DolWin4 and BorWin4 projects. The company signed contracts for those projects in April 2025 and delivered key components in May 2026.
BalWin5 is planned as a 2.2 GW-class HVDC offshore converter platform. It forms part of TenneT’s next-generation offshore transmission infrastructure in Germany, which will connect large offshore wind farms in the North Sea to the German electricity grid.
The GE Vernova–Seatrium consortium received the offshore converter platform contract in December 2025. GE Vernova’s Electrification Systems business will supply the HVDC technology and the onshore and offshore converter stations.
Seatrium will design, build, transport and install the offshore converter platform.
BalWin5 is scheduled for commissioning in 2033. The project comprises an offshore converter platform in the North Sea and an onshore converter in Bremen. The two facilities will be connected by approximately 210 km of subsea cable and around 115 km of land cable.
At the offshore platform, alternating current generated by offshore wind farms will be converted into direct current. The electricity will then travel through the cable system beneath the island of Langeoog to the mainland.
From the Lower Saxon coast, the underground cable will continue to the onshore converter in Bremen. The direct current will be converted back into alternating current before entering the high-voltage grid through the adjacent substation.
