PVTIME – Clean energy think tank Ember has named 2025 as the strongest year on record for UK solar power. Its latest report reveals that the country generated 9.91TWh of solar electricity in the first half of the year. This figure is 32% higher than in the same period in 2024.
Solar generation has broken records consistently since the beginning of the year, with monthly peaks being surpassed for the last five consecutive months starting in March. On 8 July, the UK grid achieved an all-time high for instantaneous solar supply, delivering 14GW of solar power to the national network simultaneously. This was 44% higher than the average annual peak over the past five years.
Two main factors have driven this surge: record levels of sunlight during the summer and a significant increase in new solar installations. According to Josh Cornes, a market research analyst at Solar Media, the UK added over 2GW of new solar capacity in the first half of 2025. This nearly equalled the total new installations for the whole of 2024, marking the strongest start to a year in a decade. The UK’s total operational solar capacity now exceeds 22GW.
According to Ember, residential solar adoption is also at its highest level in a decade. Data from MCS, a low-carbon technology accreditor, confirms that 120,000 certified solar installations were completed across the UK in the first half of 2025. This represents a 37% year-on-year increase, breaking the previous record set in the first half of 2012.
Ember has identified two key drivers of this growth in residential solar: a 10% year-on-year increase in energy prices, equivalent to £152, and falling installation costs. According to MCS data, the average cost per kilowatt for residential solar systems has steadily decreased since summer 2023, dropping from £2,009/kW in 2023 to £1,590/kW in 2025.
The think tank also notes that the average size of residential solar systems has grown significantly since the feed-in tariff scheme for systems under 4kW ended in 2019. Over the past decade, the proportion of systems in the 4–10kW range has increased tenfold, rising from 5% in 2015 to 50% in 2025.
Ember emphasises that the UK’s renewable energy mix, combining wind and solar power, effectively balances fluctuations in energy demand caused by the country’s variable climate. While the first half of 2025 saw far more sunny days, wind power generation declined, a reversal of the trend in early 2024.
Ember’s calculations show that days with both low sunlight and low wind accounted for just 2% of recent periods. This helped push the share of gas-fired power in the grid to a record low of 21% in June. Ember analyst Frankie Mayo describes 2025 as a golden year for solar, adding that the UK is benefiting from new solar projects completed in recent years, which are reducing the country’s reliance on expensive gas when wind speeds are below average. He adds that this demonstrates the need for the UK to develop solar and wind power in tandem in order to build a strong, stable and clean electricity system that can operate year-round.
Scan the QR code to follow PVTIME official account on Wechat for latest news on PV+ES
