Renewable electricity generation in the UK hit a new record in the third quarter of 2025, with wind and solar combined providing the country’s cleanest electricity mix ever, according to the latest data from Montel Analytics.
In the three months to the end of September, total renewable energy production – including wind, solar, hydro and biomass – reached 31.9 terawatt hours (TWh), the highest third quarter figure since records began in 2014. Renewables accounted for 51% of total UK electricity generation, surpassing all fossil fuel sources combined.
Wind power led the way with 17.7 TWh, up 6% year-on-year and the highest third-quarter output ever recorded by Montel. The increase came despite several periods of cuts, particularly in September, when strong winds coupled with weak demand pushed electricity prices into negative territory for several hours.
Solar energy also posted exceptional gains, producing 6.2 TWh – the second-highest quarterly total on record, behind only the second quarter of 2025. This marked a 32% increase over the total of 4.7 TWh in the third quarter of 2024, driven by persistent sunshine and intense summer heatwaves in early July and mid-August that sent temperatures soaring and increased cooling demand across the UK.
Phil Hewitt, director at Montel Analytics, said the figures reflect the UK’s accelerating transition to renewable energy and the growing influence of clean power generation across the overall electricity mix.
“High levels of renewable energy production are symptomatic of our long-term commitment to producing more electricity from clean sources,” said Hewitt. “Wind output would have been even higher if there had not been several cuts during the quarter. Due to the high proportion of renewable energy, the need for gas-fired electricity was significantly reduced.”
The rise of renewable energy has continued to displace gas-fired electricity. Combined cycle (CCGT) plants produced 15.4 TWh in the third quarter – up slightly from last year’s record low of 13.8 TWh, but still 25% below 2023 levels, when gas generation totaled 20.5 TWh.
Meanwhile, production from the UK’s nuclear power fleet fell to 7.8 TWh, the lowest level in the third quarter since 2014. Several reactors, including Hartlepool 2, Heysham 1 and 2 and Torness 1 and 2, were out of service for maintenance and refueling during the period.
As a result, the UK’s electricity mix in the third quarter was dominated by renewables (51%), followed by gas (24%), imports (13%) and nuclear (12%).
Hewitt noted that the high share of renewable energy combined with lower demand in the summer helped stabilize wholesale electricity prices in the third quarter.
“The quarter followed the expected seasonal trend, with warmer weather easing system demand and contributing to lower gas and electricity prices than in the second quarter,” he said. “We expect this stability to continue in the fourth quarter unless geopolitical tensions – particularly in the Middle East – drive gas prices higher.”
Gas storage facilities across Europe are now almost full ahead of winter, but analysts warn that emerging La Niña conditions could bring colder than normal weather in Britain and northern Europe later in the year.
“A La Niña event typically occurs every three to five years and can bring a colder winter,” Hewitt said. “This could increase demand, accelerate destocking and add upward pressure on wholesale prices. However, this appears to be a weak La Niña event and could fizzle out.”
The new data highlights the resilience and importance of renewable energy in the UK energy system – even amid market volatility and infrastructure constraints.
Analysts said the record-breaking quarter strengthens the UK’s position as a global leader in clean energy production, while underlining the need for greater grid flexibility and storage to prevent performance degradation during periods of high demand.
As the UK enters the winter months, the balance between renewable energy production, system demand and gas market stability will be crucial to maintaining energy security – and maintaining the downward trend in wholesale prices that consumers and businesses hope will continue.
