Interconnector
A transmission link, AC or HVDC, that connects the grids of two countries, regions or market zones and allows electricity to be traded between them.
An interconnector is a high-voltage line or cable joining separate transmission systems or bidding zones. Overland links between synchronous neighbours are usually AC; subsea cables, long distances and links between asynchronous grids use HVDC.
Interconnectors let regions share reserves, smooth weather-driven variability across larger areas and import cheaper power. In Europe, flows are allocated through market coupling on the day-ahead market, so power moves from low-price to high-price zones until the link is full or prices converge. The congestion income equals the price spread multiplied by the flow.
The EU has a target of at least 15% interconnection capacity relative to installed generation by 2030. Notable projects include NordLink (Norway–Germany, 1.4 GW, 623 km), North Sea Link (Norway–UK, 1.4 GW, 720 km, the longest subsea interconnector when commissioned in 2021) and Viking Link (UK–Denmark, 1.4 GW, 765 km, 2023). Great Britain had around 10 GW of interconnection by 2025.
Studies by ENTSO-E and ACER estimate that full market integration yields EU welfare gains of several billion euros per year, and that more cross-border capacity reduces curtailment and required backup capacity.
Related terms
All terms →- HVDC (High-Voltage Direct Current)
Transmission technology that carries bulk power as direct current, with lower losses over long distances and the ability to link asynchronous grids.
- Day-ahead market
A wholesale electricity auction held the day before delivery that sets hourly or quarter-hourly prices and schedules for the following day.
- Curtailment
Deliberate reduction of a generator’s output below what it could produce, usually wind or solar, because of grid, market or system constraints.
- Transmission and distribution losses
Electricity lost as heat and through non-technical causes between power plants and end users, usually expressed as a share of energy supplied.
- Variable renewable energy (VRE)
Renewable generation whose output varies with weather and time of day, mainly wind and solar PV, and cannot be fully dispatched.
- Capacity credit
The fraction of a resource’s nameplate capacity that can be counted on to meet peak demand, used in adequacy planning and capacity markets.