# Offshore wind and Underground, submarine and superconducting cables

Every megawatt-hour from an offshore wind farm reaches land through subsea export cables, so a few cable makers with factories booked into the late 2020s, and the risk of a single cable fault, set how fast and how reliably offshore wind can grow.

Source page: https://www.materialinsights.org/links/offshore-wind-and-underground-submarine-and-superconducting-cables/

[Offshore wind](https://www.materialinsights.org/energy/e_offshore_wind/) (energy) and [Underground, submarine and superconducting cables](https://www.materialinsights.org/energy/e_cables/) (energy): 4 relationships.

## How they are linked

### 1. Export link to shore

*Physical flow · Strong · Offshore wind power flows to shore through subsea cables*

A farm's turbines feed array cables to an offshore substation, and export cables carry all of its output to the onshore grid, so no cable means no sales.

- **100%** of offshore wind output passes through subsea cables
- **about 80 to 100 km** cable route length beyond which HVDC export saves cost over AC
- **about £270 million** export cable cost for a 1 GW floating offshore wind farm

HVDC links need converter stations at each end and pay off only on longer routes, so distant farms rely on the few firms that make HVDC cable. Export cable is a large single item: about £270 million for a 1 GW floating farm in a UK industry guide.

Sources: [BVG Associates for ORE Catapult and The Crown Estate](https://guidetofloatingoffshorewind.com/guide/b-balance-of-plant/b-1-cables/b-1-2-export-cable/); [Material Insights (World Bank, FRED, IMF data)](https://www.materialinsights.org/energy/e_offshore_wind/correlation/)

### 2. Cable factory bottleneck

*Shared risk · Strong · Cable supply limits offshore wind build-out*

Only a handful of firms make high-voltage subsea cable at scale, and their factories and laying ships are booked years ahead, so cable delivery slots often decide when a farm can be finished.

- **about 75%** HVDC cable market reportedly held by NKT, Prysmian and Nexans, 2024
- **about 50%** UK HVDC cable supply used by offshore wind, the rest by interconnectors and grid
- **a little over 60** cable-laying ships worldwide, 2024

In 2024 most submarine cable makers were reported fully booked until the late 2020s, with Nexans's Halden plant sold out to at least 2028. The UK's 2026 supply chain study still expects a severe HVDC shortfall in 2025 to 2026 and rates export cables a medium-high risk, even though new plants in Europe and Asia have eased constraints slightly; grid operators such as TenneT, buying in bulk, compete for the same slots.

Sources: [Offshore Magazine](https://offshore-mag.com/renewable-energy/article/55240474/shortage-of-submarine-power-cables-poses-threat-to-offshore-wind-market); [UK Government (GOV.UK)](https://assets.publishing.service.gov.uk/media/69ef36b020a498c16734afcc/UK-renewables-deployment-supply-chain-readiness-study-2026-update.pdf)

### 3. Single point of failure

*Shared risk · Strong · A cable fault cuts farm output*

An export cable carries the output of the whole farm or a large part of it, so one fault can stop sales until a repair ship and spare cable are found.

- **about 83%** offshore wind losses and insurance claims linked to cable failures
- **$10 to 30 million** typical loss from an export cable failure, repair plus lost output
- **about 60 days** average export cable repair downtime

Array cable faults cost less, $1.2 to 12 million, and take about 40 days to fix, because they cut only a string of turbines. DNV traces many failures to poor interface design and designs not matched to site conditions, so cable engineering and spare holdings feed straight into insurance cost and farm availability.

Sources: [DNV](https://www.dnv.com/article/80-percent-of-insurance-claims-in-offshore-wind-are-related-to-subsea-cable-failures-how-can-the-industry-manage-these-risks/)

### 4. Price link: main input

*Cost and price · Weak · Both ways*

Export cables are a large cost and a supply bottleneck, yet the US cable price index and the offshore turbine cost proxy show no monthly link and only a weak yearly one.

- **0.00** monthly change correlation
- **0.23** 12-month change correlation
- **0.38** fitted elasticity

Cables are bought on multi-year contracts, often years before installation, so spot cable prices reach farm costs slowly; the site finds a lag of about 2 months and only a weak yearly link. Over the longer run the pressure is clear: power wire and cable prices rose more than fivefold from 2004 to 2022.

Sources: [Material Insights (World Bank, FRED, IMF data)](https://www.materialinsights.org/energy/e_offshore_wind/correlation/); [Offshore Magazine](https://offshore-mag.com/renewable-energy/article/55240474/shortage-of-submarine-power-cables-poses-threat-to-offshore-wind-market)

## For investors

### Key learnings

1. Cable slots as much as turbines set completion dates, with most subsea cable plants reported booked into the late 2020s.
2. Cable failures account for about 83% of offshore wind losses and insurance claims, so cable design and spares belong at the centre of due diligence.
3. Cable and offshore wind cost indexes barely move together month to month (0.00), so cable risk shows up through contracts and delays rather than spot prices.

### What to track

- **Order backlogs at Prysmian, NKT and Nexans**: Longer backlogs mean later slots for new farms and firmer cable pricing (Quarterly · company results)
- **Cable failures and repairs at operating farms**: More faults raise insurance costs and cut availability (As reported · operator and insurer notices)
- **New HVDC cable factory openings**: Added capacity eases the bottleneck (As announced · company and government releases)

## For policymakers

### Key learnings

1. Offshore wind targets depend on reserving cable factory capacity and laying ships early; the UK study finds half of HVDC supply already goes to offshore wind.
2. India plans to auction 37 GW of offshore wind by 2030 but cancelled 4.5 GW of tenders in August 2025 for lack of bidders, so a clear grid and export cable plan is part of making tenders bankable.
3. Protecting subsea cables from faults and damage is a reliability and security issue as well as a commercial one.

### What to track

- **SECI offshore wind tender results**: Shows whether developers return to India's offshore auctions (Per tender · SECI and MNRE)
- **Cable and vessel capacity against planned offshore wind and interconnector demand**: A widening gap signals delayed targets (Yearly · government supply chain studies)

## India

India plans to auction 37 GW of offshore wind by 2030, starting with 1 GW split between Gujarat and Tamil Nadu and backed by ₹7,453 crore of viability gap funding, but SECI cancelled 4.5 GW of tenders in August 2025 after they drew no developer interest.

## Sources

1. [Guide to a floating offshore wind farm: export cable](https://guidetofloatingoffshorewind.com/guide/b-balance-of-plant/b-1-cables/b-1-2-export-cable/), BVG Associates for ORE Catapult and The Crown Estate
2. [Shortage of submarine power cables poses threat to offshore wind market](https://offshore-mag.com/renewable-energy/article/55240474/shortage-of-submarine-power-cables-poses-threat-to-offshore-wind-market), Offshore Magazine (2024)
3. [UK renewables deployment supply chain readiness study: 2026 update](https://assets.publishing.service.gov.uk/media/69ef36b020a498c16734afcc/UK-renewables-deployment-supply-chain-readiness-study-2026-update.pdf), UK Government (GOV.UK) (2026)
4. [80% of insurance claims in offshore wind are related to subsea cable failures](https://www.dnv.com/article/80-percent-of-insurance-claims-in-offshore-wind-are-related-to-subsea-cable-failures-how-can-the-industry-manage-these-risks/), DNV (2024)
5. [India reconsiders 1 GW offshore wind tender after earlier auctions fail to attract bidders](https://www.downtoearth.org.in/energy/india-reconsiders-1-gw-offshore-wind-tender-after-earlier-auctions-fail-to-attract-bidders-official-tells-dte), Down To Earth (2026)
6. [Price correlation, Material Insights](https://www.materialinsights.org/energy/e_offshore_wind/correlation/), Material Insights (World Bank, FRED, IMF data)