Insights
2 minutes
30/06/2026
Record temperatures are testing solar – but not in the way many people think
Higher temperatures reduce panel efficiency but intense sunshine boosts performance
· Solar panels generate electricity from sunlight. While higher temperatures may reduce panel efficiency, bright, sunny conditions are the main contributors to electricity generation.
· Solar projects are incorporating the likelihood of more extreme heat events into development protocols to insulate plants from a warmer future.
· Foresight Solar is investing in selecting panels with stronger temperature performance to monitoring operating conditions in real time, adapting its portfolio for a changing climate.
The current spell of extreme heat in Europe is the most severe and widespread ever recorded across the region, according to researchers at World Weather Attribution.
As temperatures climb above seasonal norms, attention naturally turns to the resilience of critical infrastructure – from transport networks and cooling techniques to power grids and the renewable energy assets that power them.
For solar power, a common assumption is also one of the biggest misconceptions. Many people believe that hotter weather means more solar generation. Solar panels thrive, however, on sunlight, not heat.
Hotter isn't always better
Solar panels convert sunlight into electricity using semiconductor cells. As these cells become hotter, their electrical properties change, making it less efficient for electricity to flow through the material.
The result is a reduction in power output.
Most manufacturers test solar panels under Standard Test Conditions, which assume a cell temperature of 25°C. In practice, panels operating during a UK heatwave can reach surface temperatures as high as 65°C, even when air temperatures are considerably lower.
The tests indicate that modern utility-scale solar panels typically lose around 0.3% to 0.4% of their power output for every degree Celsius above the 25°C reference point.
That does not mean generation collapses during hot weather. Far from it.
The abundant sunshine accompanying a heatwave tends to outweigh the efficiency losses caused by higher temperatures. Solar farms continue producing large volumes of electricity, although each panel generates slightly less than it would under cooler conditions with the same level of sunlight.
Summer temperatures build gradually throughout the day. Solar panels are much cooler during the morning and evening, while longer daylight hours mean solar farms continue generating electricity well before and after the hottest part of the afternoon.
For comparison, a cloud passing over an array can reduce the sunlight reaching a panel by 50% or more. That is why clear, hot summer days remain among the most productive days of the year for solar generation.
For investors, this is an important distinction. Annual solar production depends far more on the amount of available sunshine than on air temperature. A warm, sunny summer generally delivers significantly higher output than a cool, overcast one, even after accounting for temperature-related efficiency losses.
How will climate change affect solar generation?
Climate change is affecting the frequency with which solar assets experience extreme temperature conditions.
Climate projections consistently indicate that Europe will experience more frequent, longer-lasting and more intense heatwaves over coming decades. The latest event follows another exceptional early-summer heatwave just a few weeks earlier, highlighting a trend towards increasingly persistent higher temperatures.
For solar operators, that means panels are likely to spend more time producing electricity at elevated temperatures.
While the efficiency impact on any individual day remains relatively modest, prolonged periods of high temperatures become an increasingly important consideration in long-term asset management, performance modelling and investment decisions.
At the same time, solar generation becomes even more valuable during these periods.
Heatwaves often coincide with increased electricity demand as businesses and households require additional cooling, from fans to air conditioning. Even operating slightly below peak efficiency, solar farms can provide substantial volumes of cheap, homegrown, low-carbon electricity precisely when power systems need it most.
How is Foresight Solar adapting?
Preparing for a warmer climate is becoming an increasingly important part of asset management. Operational excellence is at the core of Foresight Solar’s business model, and the UK portfolio has outperformed budget in nine of the last 12 years.
The Company views climate resilience as an integral component of long-term infrastructure investment rather than a response to isolated weather events.
· Technology selection. One of the first considerations begins with technology selection. Modern modules lose less performance as operating temperatures rise. The new modules being installed across the UK portfolio as part of the enhancement programme are newer, more efficient equipment that will help insulate the portfolio.
· Procurement and development. Supporting equipment is also designed for increasingly demanding operating conditions. Inverters, transformers and other electrical components need to operate reliably during periods of elevated ambient temperatures, helping maintain overall system performance throughout heatwaves.
· Engineering. Engineering design also plays a significant role. Solar panels are mounted with sufficient clearance above the ground to promote natural airflow, helping dissipate heat. The spacing between panel rows, mounting structures and site layouts are carefully planned to maximise cooling and maintain energy yield.
· Real time monitoring. Continuous monitoring is the other important element. Foresight Solar’s operating teams monitor asset performance in real time, tracking panel temperatures, weather conditions and electricity output. This allows operators to distinguish between expected temperature-related performance changes and potential equipment issues requiring intervention.
Adaptation is an operational requirement
The evidence suggests that while hotter temperatures do reduce the efficiency of individual solar panels, the overall picture is considerably more nuanced than the headline assumption that "heat is bad for solar".
Solar panels continue generating significant amounts of electricity during heatwaves because the sunlight that drives production remains abundant. The challenge for operators is ensuring that assets are designed, monitored and maintained to perform efficiently as extreme heat becomes more common.
As climate change reshapes weather patterns across the UK and Europe, resilience will become just as important as generation capacity itself.
For long-term infrastructure investors like Foresight Solar, adapting to that reality is already part of the job.
