Solid-State Transformers for Direct Offshore Wind Turbine Grid

The conventional architecture of an offshore wind farm uses an iron-core step-up transformer at each wind turbine, an inter-array AC collection cable network, an offshore substation with another iron-core transformer, and a high-voltage AC or HVDC transmission link to shore. Total power-conversion losses across the chain run 4 to 8 percent depending on water depth, distance to shore, and specific equipment choices. Solid-state transformer (SST) architectures applied at the turbine and at the offshore substation can reduce these losses by 2 to 4 percentage points and substantially compress the offshore substation footprint.

Academic research has produced detailed designs for offshore-wind SST applications. One representative reference uses 3.3 kilovolt silicon carbide MOSFETs in a DC-DC SST topology designed to interface a direct-drive permanent-magnet synchronous generator (PMSG) wind turbine to a series-DC collection network. The reported peak efficiency is 98.1 percent, with converter material cost of approximately 46,500 euros per megawatt at the turbine rating. The series-DC collection architecture eliminates the offshore AC substation entirely; the inter-turbine DC link feeds directly into an onshore HVDC converter station.

The series-DC architecture requires galvanic isolation between turbines to prevent fault propagation across the collection network. The SST at each turbine provides that isolation through its medium-frequency transformer. The combination is a key enabler of an entirely DC-based offshore wind farm collection system, which has been a research goal in the European wind industry for over a decade but has been blocked by the lack of commercial DC-DC converters at the required voltage and power class.

Commercial deployment of offshore-wind SST architectures is still in pre-production stage. Siemens Gamesa, GE Vernova, and Vestas — the three dominant Western offshore-wind turbine OEMs — have each disclosed research-stage work on next-generation turbines with integrated power-electronics that displace the conventional step-up transformer. None has committed to a commercial product timeline. The supply-chain readiness for 3.3 kilovolt and higher SiC MOSFETs from Wolfspeed and Infineon is the gating factor through 2027.

The economic case for offshore-wind SST adoption is particularly strong because the offshore substation footprint cost is significant — typically 10 to 15 percent of a project’s total capex. Eliminating or substantially shrinking that footprint reduces both initial capex and the operational and maintenance burden of a remote offshore substation that must be serviced by sea or helicopter. SST adoption in offshore wind is therefore not merely an efficiency optimization but a fundamental project-economics shift.

Why It Matters

The development of solid-state transformers (SSTs) for direct offshore wind turbine grid connection has significant implications for the US utilities and grid operators, including ERCOT, PJM, and CAISO. By reducing power-conversion losses and compressing the offshore substation footprint, SSTs can substantially improve the economics of offshore wind projects. This is particularly important as data-center demand and other emerging loads drive growth in renewable energy capacity. The use of 3.3 kilovolt silicon carbide MOSFETs in SST architectures also highlights the importance of advancements in power electronics and semiconductor technology. As the industry continues to evolve, we can expect to see further innovations in battery energy storage systems (BESS) economics and other areas. FERC orders and IEEE/NERC standards will also play a crucial role in shaping the integration of SSTs into the grid. The potential for SSTs to enable entirely DC-based offshore wind farm collection systems is a key trend to watch, with major OEMs like Siemens Gamesa, GE Vernova, and Vestas already exploring this technology. As the supply chain for high-voltage SiC MOSFETs matures, we can expect to see commercial deployment of SSTs in offshore wind projects, driving a fundamental shift in project economics and efficiency.

Critical Perspective

Editorial correction: This post is part of MGRID’s Solid-State Transformer industry coverage. As of May 2026, that body of work systematically framed manufacturer announcements, funding rounds, and laboratory demonstrations as commercial deployments. The reality is that field-deployed commercial-class SST in revenue service globally is measured in single digits, and almost every product cited in this series is at “announced” or “funded” stage, not “operational.” Readers should treat the specific claims in this post against the standards documented in our SST Industry Reality Check (the per-claim audit table maps marketing language to verifiable deployment status). The corrective article is the canonical reference for SST industry reality; this post remains published with its original framing so the editorial drift is traceable.

Related Coverage

• Wolfspeed’s 200mm Silicon Carbide Wafer Capacity Is the Single Biggest 2026 Bottleneck on Solid-State Transformer Production: Wolfspeed’s SiC capacity bottleneck impacts SST production for wind
• onsemi EliteSiC Is the Third Silicon Carbide MOSFET Supplier the Solid-State Transformer Industry Depends On Behind Wolfspeed and Infineon: onsemi’s SiC MOSFETs are key for SSTs, like in wind
• Mitsubishi Electric’s Quieter Solid-State Transformer Strategy: SiC Power Modules for Japanese Rail and Selected US Industrial Customers: Mitsubishi Electric’s SiC SST strategy for rail and industrial
• Silicon Carbide vs Gallium Nitride: Why Every Medium-Voltage Solid-State Transformer Uses SiC and Where GaN Might Still Win: SiC is preferred for medium-voltage SSTs, including wind