Negative electricity prices UK: why they keep rising
Negative electricity prices in the UK are rising because Britain keeps adding wind and solar faster than demand grows. Solar has also changed when they happen: on Agile Octopus, plunges have moved from the middle of the night to the middle of the day. 2026 has already had more negative half-hours than any full year since at least 2019.
The record, in brief
A negative price means you are paid for each unit of electricity you use. Octopus calls this Plunge Pricing, and it happens when Britain generates more power than it needs.
Wattly's price history has the counts for every month, region and year. See the Agile price history for 2026, with negative half-hours by month, or go back to Agile prices in 2019 for comparison. This post looks at why the numbers keep climbing.
More wind and solar than ever
Official figures from the Department for Energy Security and Net Zero (DESNZ) show steady growth in both. Capacity means the most a technology can produce at full output.
| UK installed capacity | End of 2019 | End of June 2026 | Change |
|---|---|---|---|
| Wind (onshore and offshore) | 23.9GW | 33.6GW | +40% |
| Solar | 13.3GW | 22.4GW | +68% |
More capacity means more hours when wind and sun together produce more than the country is using. When supply outstrips demand, wholesale prices can drop below zero, and Agile follows them down.
Solar has moved plunges to midday
The clearest sign of solar's role is the time of day. The table shows when Agile's negative half-hours fell in London (region C) each year.
| Year | Between 10am and 4pm | Between 10pm and 7am |
|---|---|---|
| 2019 | 0% | 100% |
| 2020 | 31% | 58% |
| 2021 | 0% | 100% |
| 2022 | 10% | 83% |
| 2023 | 22% | 70% |
| 2024 | 40% | 51% |
| 2025 | 50% | 39% |
| 2026 (to 11 October) | 68% | 19% |
Early plunges were a wind story: blustery nights when hardly anyone was using power. Wind still drives the overnight ones. But solar output peaks around midday, and with 68% more solar capacity than in 2019, sunny days now tip the grid into surplus too.
Weekends matter as well, because offices and factories use less. In 2026, 78% of London's negative half-hours fell on a Saturday or Sunday.
Why the rise is bumpy
Capacity sets the long-term direction, but weather and demand decide each year.
- 2020 was an early spike. Elexon, which runs the electricity settlement system, found demand in April and May 2020 was 19% lower than a year earlier, as Covid lockdowns shut offices and factories.
- 2021 almost had none. It was a weak year for wind: UK wind farms generated 64.9TWh, down from 75.6TWh in 2020, according to DESNZ.
- 2025 ended slightly below 2024, mainly because November and December 2025 had almost no plunges.
One caution: Octopus has changed how Agile prices are worked out from wholesale prices since 2019. Treat the early years as a guide to the trend rather than an exact like-for-like comparison.
What it means for Agile customers
Midday plunges are easier to use than 3am ones for many households. A washing machine, dishwasher or hot water cylinder can be timed for lunchtime at the weekend. Electric car owners who are home during the day gain most.
The cheapest hours are no longer only overnight. Wattly's cheapest time to use electricity finder picks the cheapest block for any task length. Check today's and tomorrow's Agile prices once they are published, usually around 4pm.
Plunges happen in every region on the same days, but how deep they go differs slightly. You can compare Agile prices across all 14 regions.
FAQ
Why are negative electricity prices rising in the UK? Wind and solar capacity keep growing, so there are more hours when generation is higher than demand. Weather and demand still cause big swings from year to year.
Why are electricity prices negative? Prices fall below zero when generation, mostly from wind and solar, is higher than demand. Agile follows wholesale prices, so it goes negative too.
What time of day are Agile prices negative? In 2026, 68% of negative half-hours in London fell between 10am and 4pm, mostly at weekends. As recently as 2024, about half were overnight.
Is it wind or solar causing negative prices? Both. Wind drives the overnight plunges, while solar is behind the growing number around midday.
Will negative prices keep increasing? More wind and solar is being built, which makes surpluses more likely. Weather and demand still decide how many plunges each year brings.