Western Europe solar irradiance increased by 50% in Spring – Solargis

In March 2025, parts of Belgium, Germany, and the UK saw levels of Global Horizontal Irradiation (GHI) increase up to 50% above long-term averages, according to data from Solargis. In April, most of North-Western Europe registered levels 35% above average, while Southern Europe countries—Spain, Portugal, and Italy—experienced the opposite, with up to 25% lower irradiance. Scotland registered a 35% increase in GHI compared to average figures.

Helped by the surge in solar irradiance between March and May, the UK has seen its power output rise by 42% from the same period in 2024, with solar PV generating 7.6TWh of electricity in the first five months of 2025. For the first time, the country also saw solar PV account for more than 10% of its electricity generation in April and May.

Moreover, the increased availability of solar resources has created opportunities for higher-than-expected energy yields and “underscores the growing need for precise forecasting and project evaluation solutions”, according to Solargis.

Due to the difference between regions – with Western Europe irradiance above average this Spring and Southern Europe below – Solargis said that high-resolution time series data is becoming essential for PV developers and operators. “As solar stakeholders increasingly prioritise precision, adopting time series as the industry standard will support more resilient and optimised energy generation,” added Solargis.