Air pollution is holding solar back

 By Benjamin Plackett

Worldwide solar energy production is taking a beating from air pollution and dust…

A new study from Duke University in North Carolina shows how airborne particles can accumulate on solar panels to reduce their output by more than a 25 percent in some especially dusty and polluted corners of the globe.
Ironically, the worst hit regions are also those countries with the highest solar investment and potential: China, India and the Arabian Peninsula.
The research project began because when a Duke University professor was in India where a collaborating colleague showed him some rooftop solar panels coated in dust and sand.
“I thought the dirt had to affect their efficiencies, but there weren’t any studies out there estimating the losses. So we put together a comprehensive model to do just that,” said Michael Bergin, professor of civil and environmental engineering at Duke University and lead author of the study, in a statement.
Bergin, along with partners at the Indian Institute of Technology-Gandhinagar and the University of Wisconsin at Madison, decided to produce one of the first studies to find out how pollution hampers solar energy’s potential.
The researchers measured the variances in solar energy gathered by solar panels in India as they became dirtier over time. The data showed a 50 percent hike in efficiency after each time the panels were cleaned having previously being left alone for several weeks.
The scientists also took samples of the dirt coatings to analyze its makeup. They found that 92 percent of it was composed of dust and sand. The remaining eight percent came from human-made pollutants.

Shanghai at sunset. The sun has not actually dropped below the horizon yet, rather it has reached the smog line (Suicup, Wikimedia)

While the pollutants are only a small portion of the grime, they are much more efficient at blocking light from penetrating the solar panels. Bergin’s calculations showed that this meant the human contribution to solar energy reduction was approximately the same as the “natural” dust and sand.
“The manmade particles are also small and sticky, making them much more difficult to clean off,” he said. “You might think you could just clean the solar panels more often, but the more you clean them, the higher your risk of damaging them.”
In addition to the solar surface buildup, airborne particles also prevent sunlight from reaching the panels.
Bergin used data from NASA that estimates the global distribution of airborne pollutants and the amount of particles that sticks to surfaces. This allowed him to estimate the total loss of solar energy production around the world. The Arabian Peninsula, Northern India and Eastern China seem to suffer the most with 17 to 25 percent loss if you assume monthly cleanings. But if cleanings take place every two months, then those numbers rise to 25 or 35 percent.
In the Arabian Peninsula the biggest culprit is dust and sand. In China and India it is human pollution that is more to blame.
“We always knew these pollutants were bad for human health and climate change, but now we’ve shown how bad they are for solar energy as well,” said Bergin. “It’s yet another reason for policymakers worldwide to adopt emissions controls.”

SEE MORE: The carbon climate solution by Michelle Leslie

about the author
Benjamin Plackett
I’m a journalist based in London. I report on all things science, tech, and health for a number of different publications. My work has been published by The Daily Dot, Inside Science and CNN among others. I earned my M.A. in Journalism at New York University and my B.Sci in Biology from Imperial College, London.