UK solar power hits record levels amid sunniest spring on record

5 June 2025

Solar panels on British rooftops and in solar farms generated more electricity than ever before during the first five months of 2025, according to new analysis by Carbon Brief.

A total of 7.6 terawatt hours (TWh) of electricity was produced between January and May, up 42% compared to the same period last year. This marks a 260% increase over the past decade, driven by both an expansion in installed capacity and an exceptionally sunny spring. The Met Office reported 653 hours of sunshine between March and May, the highest for any UK spring since records began in 1910.

Solar generation reached an all-time half-hourly high of 13.2 gigawatts (GW) on 6 April, while monthly averages topped 3GW in April and May. In both months, solar accounted for more than 10% of all electricity produced—a milestone achieved only four times previously.

The surge in solar output has helped reduce reliance on imported gas. Carbon Brief analysts estimate that the electricity generated by solar so far this year has displaced the need for around 16TWh of gas imports, saving an estimated £600 million and preventing 6 million tonnes of carbon dioxide emissions.

Despite the growth, solar power remains the UK’s sixth-largest electricity source in 2025 to date, behind gas, wind, imports, nuclear and biomass. However, capacity is expanding quickly. After years of stagnation, total installed solar capacity rose to 20.2GW at the end of 2024 and is projected to reach at least 45GW by 2030 as part of government targets.

Energy Secretary Ed Miliband has approved several large-scale solar projects since taking office, while rooftop solar installations are also on the rise. The UK added 2.3GW of solar capacity in 2024 and is on track to add up to 3.5GW in 2025.

The UK’s electricity system is being prepared for a zero-carbon future, with the National Energy System Operator aiming to run without fossil fuels for short periods as early as this year. Challenges posed by variable sources like solar and wind—including grid stability and energy pricing—are being addressed through technologies such as battery storage, grid interconnectors, and alternative sources of inertia.

The data used in the analysis covers Great Britain, excluding Northern Ireland, which operates as part of the all-Ireland electricity market.