Questions people ask
about the UK grid
Plain answers, with the current numbers from this site. Every figure links to how it was worked out.
Why are wind farms paid to switch off in the UK?
Because the wires cannot carry the power. Most British wind is built in Scotland and off the coast; most demand is in the south. When more power wants to flow south than the network can carry, the grid operator pays wind farms behind the bottleneck to stop, and pays gas plants beyond it to start.
In the last year that was £410m paid to switch off wind farms — about 11.8 TWh of clean electricity thrown away. See which constituencies.
What is wind curtailment?
Curtailment is the industry word for switching off generation that could otherwise run — in Britain, usually wind farms told to reduce output because the network cannot move their power to where it is needed. The generator is compensated and the cost lands on bills.
This site says switched off rather than curtailed throughout, because the jargon hides what is happening.
How much do grid constraints add to my electricity bill?
About £92 a year for a typical household. Britain's constraint bill over the last year was £2.5bn, spread across roughly 27.3 million GB households. That covers switch-off payments, paying gas plants to turn up instead, and keeping the strained grid stable.
It is a national figure — the same in every constituency. Only the total for a seat varies, with how many households it has.
How much approved renewable energy is not being built in the UK?
About 23 GW has held planning permission for two years or more without being built — enough to supply a year's electricity to roughly 11.8 million homes. The obstacle is usually the grid connection queue, not planning. See the worst-affected constituencies.
What is the B6 boundary and why does it matter?
B6 is the transmission boundary between Scotland and England — the wires crossing the border, and the biggest bottleneck in the British grid. About 4 GW fits through; on windy days up to 11.6 GW wants to. Last year the wanted flow met or beat the limit about 37% of the time.
Two new subsea links, Eastern Green Link 1 and 2, are due in 2029. See the whole picture.
Do batteries stop wind farms being switched off?
They help, and much sooner than new wires — a battery takes about eighteen months, a transmission link takes a decade. A battery behind the bottleneck charges on power that would be switched off and releases it when the wires have room; one near a city discharges instead of a gas plant turning up.
Britain has 72.1 GW approved and not built, and 5.7 GW refused in five years. They shift power in time, not distance — the wires still need building. The full explainer.
How do I find out what this costs in my constituency?
Enter your postcode on the front page, or open the map and click your seat. All 650 Westminster constituencies have a page with the switch-off payments, the approved-but-unbuilt projects, the bill impact and the local battery projects.
Why doesn't Britain just build more transmission lines?
It is, slowly. Big transmission projects take a decade to consent and build. Eastern Green Link 1 and 2 — two subsea cables carrying 2 GW each between Scotland and England — are due in 2029. Until then, the fastest ways to cut the bill are batteries behind the bottleneck and putting demand nearer to where the power is made.
Where the numbers come from
Switch-off payments come from Elexon settlement data for the balancing mechanism; planning figures from the government's Renewable Energy Planning Database; the bill impact from NESO's balancing cost reporting; household counts from the 2021/22 censuses. Everything is open data and the full method is public, including our reconciliation against NESO's own published volumes.