Coal pollution is significantly reducing the output of solar panels, major study finds

A new study has revealed that coal pollution is significantly reducing the energy output of solar PV installations, particularly where they are located side by side, in yet another of the never-ending cascade of problems with coal-fired power.

The new research, led by the University of Oxford and University College London (UCL) and published in the journal Nature Sustainability, mapped and assessed more than 140,000 solar PV installations across the globe using satellite data – data that is now available for all to see in a new data visualisation tool at https://pvfacilitymap.uk/.

The researchers combined atmospheric data on air pollution with the satellite data of solar PV installations to calculate how much sunlight is lost, and how this lost sunlight results in reduced electricity generation.

The data reveals that aerosols in the atmosphere reduced global solar electricity output by 5.8 per cent in 2023 – equivalent to 111 terawatt-hours (TWh) of lost electricity, or the amount generated by 18 medium-sized coal-fired power plants.

Tracing the origins of these aerosol particles back to their original source revealed coal-fired power generation to be a major contributor.

Coal plants emit a fine layer of pollution particles that scatter and absorb sunlight, reducing the amount that reaches nearby solar panels, causing them to generate less electricity than they otherwise would.

This effect was particularly evident in China, where solar and coal capacity have been expanding in parallel and are often co-located. According to the researchers, regions in China with high coal capacity closely aligned with areas experiencing the greatest solar PV loss.

That meant that the world’s largest solar producer – generating 793.5 TWh of solar electricity in 2023, or 41.5 per cent of the global total – also experienced the largest losses from aerosols, with total solar output reduced by 7.7 per cent.

The researchers estimated that approximately 29 per cent of aerosol-related solar PV losses in China came specifically from coal-fired power plants.  

The study also highlights the fact that these solar power losses due to coal pollution are a significant and often overlooked constraint on the clean energy transition.

For example, between 2017 and 2023, new solar PV installations across the globe added an average of 246.6 TWh of electricity each year. However, aerosol-related losses from existing systems reached 74 TWh – equivalent to nearly one-third of the gains from the newly added capacity.

“We are seeing rapid global expansion of renewable energy, but the effectiveness of that transition is lower than often assumed,” said Dr Rui Song, of the department of physics at the University of Oxford, and also the Mullard Space Science Laboratory at UCL, who was also the lead author of the paper.

“As coal and solar expand in parallel, emissions alter the radiation environment, directly undermining the performance of solar generation.

Ironically, while this effect was particularly evident in China, China is also the only major region showing a sustained improvement in aerosol-related solar PV losses, with losses declining by an average of 0.96 TWh per year, or 1.4 per cent annually, between 2013 and 2023.

According to the researchers, this is likely due to China’s stricter emissions standards and widespread adoption of ultra-low-emission technologies within its coal-fired power plants.

But even the findings from this latest research may not tell the whole story.

“Air pollution doesn’t just block sunlight – it also changes clouds, which can cut solar power even further,” added Dr Song.

“That means the real impact is likely to be bigger than we’ve measured, so we may be overestimating how much solar power can contribute to reducing emissions if we do not get pollution from coal power under control.”

The methods used to assess the impact of coal pollutants on solar panels will also eventually be able to expand to cover other pollutants in our atmosphere.

“Global satellite imaging enabled us to map the inexorable rise of cheap non-polluting solar power during daylight hours,” said Professor Jan-Peter Muller, from the Mullard Space Science Laboratory at UCL and a corresponding author of the report.

“In the near future, we will be able to observe the impacts of dust and smoke particles on reducing solar energy at the Earth’s surface in real-time every 10 minutes from geostationary satellites spanning the Earth.”

If you would like to join more than 29,000 others and get the latest clean energy news delivered straight to your inbox, for free, please click here to subscribe to our free daily newsletter.

If you wish to support independent media, and accurate information, please consider making a one off donation or becoming a regular supporter of Renew Economy. Please click here. Your support is invaluable.