The latest National Audit Office (NAO) report has prompted renewed debate about wind farms being paid to switch off and the cost of upgrading Britain's electricity network. Some have suggested this proves there is too much renewable energy on the system, or that vital grid upgrades should be cancelled to save money.
The report actually highlights a different problem: Britain has built renewable generation faster than it has expanded the electricity network needed to transport that power around the country. The result is a grid bottleneck and by accelerating – not cancelling – grid upgrades, consumers could be £30 better off overall. Not upgrading the grid would cost consumers more.
Key facts
Renewables generated a record 52.5% of UK electricity in 2025.
Wind farms are sometimes paid to switch off because the grid cannot move electricity efficiently around the country.
The National Audit Office says network upgrades are needed to reduce these costs.
Ofgem estimates households will be £30 better off overall if those upgrades are delivered on time.
Delaying grid investment would increase costs and could slow economic growth.
SSEN Transmission, SSE’s transmission business, is investing £29bn upgrading the grid in the north of Scotland.
What does the National Audit Office (NAO) report say about the grid?
The NAO report does not conclude that Britain has too much renewable energy. It concludes that the electricity network needs to catch up with the renewable generation already built. Upgrading the grid will reduce constraints, make better use of renewable power and save consumers money compared with delaying investment.
Does Britain have too much renewable energy?
No. Britain's challenge is not having too much renewable power. It is having an electricity network that has not expanded quickly enough to keep pace with new renewable generation.
Over the last decade, Britain has built renewables where the resource is strongest – and with great success. Renewables generated a record 52.5% of UK electricity in 2025, marking the second year in a row they supplied more than half of total generation.
How do renewable energy projects affect UK energy bills?
When global gas prices rise because of international events, renewable energy helps reduce Britain's exposure to those price shocks. Every unit of electricity generated from UK wind power reduces the amount of gas Britain needs to import. That helps shield households and businesses from volatile international energy markets.
At a time when gas prices are rocketing thanks to global conflicts - forward prices for winter have topped 200p/therm recently - there is an obvious advantage to using renewables. We reckon wholesale electricity costs during this latest conflict have been around 30% lower than they would have been if we didn’t have these renewables.
Most renewables are on fixed-price contracts, which means when prices soar, they pay the difference back to consumers. And they push the most expensive gas stations off the system, suppressing market prices too.
Of course, ‘it could have been even worse’ isn’t the most compelling argument when families are dealing with painful bill increases, but it happens to be true. And it’s important to acknowledge this because it highlights the often unseen protection renewables give us.
Why does Britain need more electricity generation?
Britain will need significantly more electricity over the coming decades as transport, heating, industry and digital infrastructure increasingly rely on power.
Whether it’s EVs, data centres or simply to fuel a growing economy, electricity demand is increasing. And this is happening at a time when the nuclear and gas power stations we currently rely on are due to start shutting down.
Nuclear has for decades been plagued by delays and cost overruns. Gas generation is an option, but global supply chains are struggling to keep pace with demand. The cost of new turbines has more than trebled since the UK's last gas power station was built. Even if Britain wanted to build a new gas station today, turbine availability remains limited well into the 2030s. And, to make an obvious point, relying more on gas would increase our vulnerability to global events.
There are things we can and should do to make better use of the assets we have by building more flexibility into the system, but whichever way you look at it we’re going to need more generation and renewables is the only technology that will turn up on time at a competitive price.
Why are wind farms paid to switch off?
Wind farms are sometimes paid to reduce generation because electricity cannot always be transported to where it is needed. These payments, known as constraint payments, are largely the result of network bottlenecks rather than excess renewable generation.
As the National Audit Office points out, the problem is that the electricity network hasn’t kept pace with renewables build, meaning the grid is often too overloaded. It means we can’t harness the full potential of the renewables the UK has built.
That's finally being addressed through a huge national grid upgrade programme that will see around £70bn of transmission investment in Great Britain between 2025 and 2031. For SSE’s part, our transmission business is investing £29bn rewiring the north of Scotland.
Despite the size of that investment, the NAO’s report is clear that consumers will save money because these upgrades will enable pent-up renewables to be more fully used. Ofgem's assessment is that households will be around £30 better off by 2030 than if the upgrades are delayed.
What happens when wind farms are paid to switch off?
When we pay wind farms to switch off, we often have to pay gas generators to switch on. And because gas plants are running less often, they need higher prices when they do run to cover their costs.
Consumers end up paying twice, once for the bottleneck and again for the substitute power. It adds to the bill, weakens our energy security, and underlines why fixing grid constraints must be a priority.
What needs to happen next?
The NAO's biggest concern isn't the scale of investment needed. It's the pace of delivery.
Too many critical projects still face delivery risks or remain tied up in the planning system. Every delay means higher constraint costs, longer waits for new connections, slower economic growth and a more expensive energy system overall.
What we're seeing today is not evidence that wind power is driving up costs. It's evidence of what happens when the network fails to keep pace with the power being generated.
Britain has one of the best renewable energy resources in Europe and a clear plan to upgrade the grid so we can make full use of it. The challenge now is delivery.
As the NAO makes clear, the question is no longer whether these upgrades should happen, but how quickly we can get them built.