40 years of experience
Our 40 years of experience in offshore energy give you proven methods, supply-chain insight, and credible governance from early feasibility to handover.
Offshore substation consulting and design
Building an offshore substation is no small task, it requires careful planning, detailed engineering, and precise execution from concept to commissioning. We are your reliable partner in bringing these pieces together with expertise and confidence.
Your partner for offshore substation design solutions
Ramboll is a global engineering, architecture and consultancy company with more than 18,000 experts that create sustainable solutions for governments and companies all over the world. We are leaders in the offshore substation market for designing offshore substation platforms from early feasibility to commissioning. We integrate electrical, structural and marine disciplines to optimise topside layout, weight and interfaces, and oversee offshore substation installation and grid compliance for large offshore wind farms.
55+ projects
Our portfolio covers HVAC and HVDC offshore substation designs ranging from 60MW to 1260MW, in addition to offshore switchyards and other critical facilities supporting offshore electrical infrastructure.1000+ experts
We are a diverse team delivering multidisciplinary services from advisory to deep engineering.Why partner with Ramboll for offshore substation consulting
As the world shifts toward cleaner energy and demand keeps rising, offshore wind farms are getting bigger than ever. Building at this scale comes with its own set of challenges, including the need to minimise electrical transmission losses, reduce cable costs, and ensuring safety-by-design alongside efficient operational strategies. Ramboll’s multidisciplinary team supports you through all these challenges.
Optimised offshore substation design
Ramboll designs offshore substations that are safe and cost-effective. Taking basis in our standard design catalogue enables efficient execution and the flexibility to frame our solutions to match your project specific needs. We shape the concept, run the electrical studies, and integrate the topsides and foundations, so the design you approve can be procured, installed, and commissioned on time. You get one partner accountable for performance, compliance and feasibility.
Multidisciplinary services across all phases
We provide comprehensive engineering and design services, spanning from initial feasibility studies to detailed design stages. We also optimise for your project economics to cut CAPEX and reduce OPEX. Additionally, our team possesses expertise as technical reviewers and owner’s engineers, with extensive experience in managing authorities and ensuring regulatory compliance. With successful projects delivered in the US, UK, South Korea, and beyond, we’ve proven ourselves as a trusted partner worldwide.
Global offshore substation platforms and installations
Key projects
From concept to detailed design, Ramboll has been involved in major offshore substation projects across the globe.
South Fork offshore wind farm
New York’s first wind farm will power 70,000 homes
Location: New York State, USA
Completion: 2023
Client: Ørsted/Eversource
Services provided: Ramboll worked with EPC contractor Kiewit, responsible for the FEED and complete detailed design of the HVAC offshore substation topside. Ramboll played a pivotal role in tailoring the design to the US market, accounting for local regulatory compliance and permitting standards.
Read more about the project
Outer Dowsing Offshore Wind
One of UK's largest, it will power 1.6 million homes
Location: Lincolnshire, UK
Completion: 2025
Client: Outer Dowsing Offshore Wind
Services provided: We delivered the FEED design for the transmission system of the wind farm, including the power systems design, onshore and offshore substations, reactive compensation platform, and cost estimates, all within an 11-month timeframe.
Shinan-Ui offshore wind farm
Leading the path towards carbon neutrality
Location: South Korea
Completion: 2026
Client: Hanwha Ocean
Services we provided: Ramboll conducted the engineering detailed design of the HVAC offshore substation, including design basis preparations, LV/HV system specifications, electrical calculations, equipment layouts, interconnection drawings, and 3D model layouts.
Read more about the project
Ramboll’s deep expertise and collaborative approach have been instrumental in developing a robust transmission system design for Outer Dowsing Offshore Wind. Their ability to integrate complex engineering disciplines while maintaining a clear focus on safety, constructability, and long-term performance has set a solid foundation for the project’s success
Marko Istenic
Electrical Systems Lead,
Outer Dowsing Offshore Wind
Beyond engineering excellence
Successful offshore substations require more than strong engineering, they need designs that cut costs, simplify maintenance, and respect the environment.
Standardised designs
Standardisation ensures every offshore substation we deliver is efficient, reliable, and ready for certification. By aligning with international codes and working with trusted suppliers, we create designs that cut costs, simplify integration, and make maintenance easier.
Modular designs
Modular concepts allow us to build offshore substations faster and smarter. From topside to auxiliary systems, our modular approach streamlines construction, reduces risks, and ensures long-term operational efficiency.
Responsible designs
We design offshore substations that cut carbon, support biodiversity, and deliver reliable performance using low-carbon materials, regenerative features, and nature-inclusive solutions.
FAQ: offshore substation topsides, HVDC/HVAC and installation
What is an offshore substation topside?
It’s the electrical production facility housing the main electrical (transformers, switchgear, protection/SCADA) and auxiliary systems that step up and export power to shore; it sits on a fixed steel jacket/monopile or (in deeper water) a floater. Typical HVAC topsides are approximately 2,000-4,000 tonnes; HVDC converter topsides are significantly larger and can be approximately 9,000–18,000 tonnes, depending on complexity and production capacity.
When should a developer choose HVDC vs. HVAC?
Use HVAC for shorter export distances and moderate capacities; HVDC becomes attractive as distance to shore and production capacity increases. Hence the HVDC offshore substation reduces electrical loss in cables and extends the feasible distance from the windfarm. The preferred option shall be validated by proper techno-commercial studies.
Can offshore substations be floating?
Yes. Floating offshore substations (FOSS) are emerging for deep water sites. Floating offshore substation design is typically more complex than bottom-fixed, requiring a larger design space and adding to the equipment complexity and performance. The projects involve additional interfaces and less mature supply chain.
How are offshore substations installed?
The predominant installation methodology is by heavy lift vessels that lift and positions the offshore substation components in sequence, Jacket & piles followed by the topside structure. Following all HV electrical cables from the turbines and to shore are carefully pulled in and connected before final hook-up and commissioning.
Why bring in a consultancy?
Projects slip on interfaces, compliance, and transport and installation, “not on steel”. A multidisciplinary partner coordinates electrical, structural, and marine disciplines, runs HVAC/HVDC trade-offs, manages weight/layout, ensures grid/protection compliance, and aligns the design with realistic installation windows and applicable codes and standards such as DNV-ST-0145.
What risks should be managed early?
Early concept or FEED design phases to establish the project basis and boundaries significantly reduces the project risks and possibly later rework. Weight growth/layout complexity (affects lift and cost), grid code/protection studies, installation logistics (vessels/ports/weather), and HSE/standards.