UK Solar Power Soars 42% After Record Sunniest Spring

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In a remarkable display of renewable energy potential, the UK’s solar farms and rooftops have achieved unprecedented electricity generation in the first five months of 2025. This achievement comes on the heels of the country experiencing its sunniest spring on record, a rare climatic phenomenon that has illuminated the path toward a greener energy future.

Recent analysis from Carbon Brief reveals that the UK’s solar installations produced an astonishing 7.6 terawatt hours (TWh) of electricity from January to May 2025. This figure represents a staggering 42% increase from the 5.4 TWh generated during the same period last year and signifies an impressive 160% rise over the past decade. Such growth not only highlights the increasing efficiency and capacity of solar technologies but also underscores their pivotal role in the nation’s energy landscape.

On 6 April, solar energy production reached a new half-hourly record of 13.2 gigawatts (GW), a remarkable achievement that saw solar power providing more than 10% of the country’s electricity generation for two consecutive months—April and May. This remarkable performance has effectively negated the need for importing gas worth approximately £600 million, which would have released around 6 million tonnes of carbon dioxide (MtCO2) into the atmosphere.

Despite these impressive numbers, solar energy remains the UK’s sixth-largest source of electricity so far in 2025, following gas (37 TWh), wind (33 TWh), imports (18 TWh), nuclear (15 TWh), and biomass (8.0 TWh). The surge in solar output this year can be attributed not only to the record-breaking sunshine but also to an increase in solar capacity, which rose to 20.2 GW in 2024, up from 17.9 GW the previous year. Looking ahead, solar capacity is projected to reach at least 45 GW by 2030, as part of the government’s ambitious goal to decarbonise the power sector and establish the UK as a “clean-energy superpower.”

Solar Record: A Deep Dive

The leap in solar output this year saw generation soar to a record 7.6 TWh in the first five months, a remarkable 42% increase year-on-year. Notably, March saw an average solar output of 2,320 megawatts (MW), a staggering 66% rise compared to the same month in the previous year. April followed suit with an average of 3,189 MW, a 53% increase, culminating in May’s noteworthy performance of 3,383 MW—making it the second-sunniest May on record.

May 2025 alone accounted for a staggering 2.5 TWh of solar-generated electricity, surpassing April’s output of 2.3 TWh and breaking the previous record of 2.1 TWh set in June 2024. To put this into perspective, the electricity generated from solar in the first five months of 2025 has effectively offset the need for an estimated 16 TWh of imported gas. The financial implications are significant; importing this gas would have cost approximately £600 million and, when burned, would have emitted about 6 MtCO2, contributing nearly 2% to the UK’s total emissions for that period.

To contextualise the scale of this achievement, the 16 TWh of avoided gas imports equates to 10% of the UK’s net gas imports for the same period last year, or approximately 10 individual Q-Max liquefied natural gas (LNG) tankers, the largest currently available. Such a substantial reduction in gas imports not only bolsters energy security but also demonstrates the growing importance of renewable sources in stabilising the UK’s energy grid.

Solar power accounted for 11.6% of the UK’s electricity generation in May 2025, marking only the fourth time in history that solar energy has breached the 10% threshold—previously achieved in June 2023, June 2024, and April 2025. Interestingly, solar energy has also made its mark globally, topping 10% of monthly global electricity generation for the first time in April this year.

The Impact of Weather and Capacity

The weather has played a pivotal role in this solar surge, with the UK enjoying 653 hours of sunshine from 1 March to 31 May 2025, making it the sunniest spring since records began in 1910. This total represents a 43% increase over the average for the period between 1961 and 1990. Prior to this year, the benchmark for the sunniest spring was set in 2020, with 626 sunshine hours.

According to the Met Office, sunshine hours in the UK have been on an upward trend, particularly since the 1980s. On average, spring months have been 15% sunnier over the past decade compared to the reference period from 1961-90. Met Office scientist Emily Carlisle has noted, “Seven of the top ten sunniest springs on record for the UK since 1910 have occurred since the year 2000.” This increasing trend in sunshine not only boosts solar energy generation but also enhances the capacity factor of solar installations—an important metric that measures actual electricity generation against the maximum theoretical output.

In early 2025, capacity factors for solar installations reached record highs, exceeding previous figures set in spring 2020, which was also characterised by unusually sunny weather. This increase in solar output per unit of installed capacity is a testament to the growing efficiency of solar technologies and the potential for further advancements in the sector.

The Path to Clean Power

While the sunny weather has significantly contributed to the record-breaking solar output this spring, the UK’s expanding solar capacity has also played a critical role. Following a period of stagnation after subsidies for solar were ended in 2015, the UK’s installed capacity surged to 20.2 GW by the end of 2024, driven by falling prices and the introduction of new projects under “contracts for difference.”

The beginning of 2025 has marked the strongest start for new rooftop solar capacity since 2012, with projections indicating that the UK is set to add between 3 to 3.5 GW of new solar capacity throughout the year, compared to 2.3 GW added in 2024. Under the leadership of Energy Secretary Ed Miliband, approximately 3 GW of new solar capacity has been approved at major sites, including the 500 MW Heckington Fen and 500 MW Gate Burton schemes.

The government is aiming for 45-47 GW of solar capacity by 2030, as part of its mission to ensure that low-carbon sources meet 100% of the UK’s electricity demand and at least 95% of generation capacity. In pursuit of this ambitious goal, the National Energy System Operator (NESO) is working towards operating the electricity system without fossil fuels for a brief period this year. Since setting this target in 2019, NESO has been preparing by contracting for zero-carbon sources of grid stability services, including “inertia” and voltage control.

Addressing Challenges in the Transition

As the UK continues its transition towards renewable energy, the increase in electricity generation from variable sources such as solar and wind presents new technical and market-related challenges. These challenges include rising instances of “negative pricing” in the electricity market, where prices drop below zero when supply exceeds demand.

However, the solutions to these challenges are well understood and are already being implemented in the UK. The buildout of battery storage systems, increased interconnector capacity linking the national grid to neighbouring countries, and the introduction of new sources of grid stability—such as flywheels—are all part of the strategy to ensure a reliable and resilient energy system.

As we move forward, it is clear that the UK is making significant strides toward a sustainable energy future. With record-breaking solar generation, ambitious government targets, and a commitment to clean energy, the nation is well on its way to becoming a global leader in renewable energy. The achievements of 2025 serve as a beacon of hope and a roadmap for other countries aspiring to meet their own net-zero goals.

As champions of net zero, let us continue to support and advocate for the transition to renewable energy, ensuring a sustainable and prosperous future for generations to come.