Solar energy revolution hits barrier: Air pollution

Researchers from Duke University found that air pollution, specifically airborne particles, which accumulate on solar cells, is cutting solar energy output by more than 25 percent in certain areas of the world, causing billions of dollars of losses. The research was published this week in the journal Environmental Science & Technology Letters. 
The hardest hit regions happen to be those currently investing the most in solar energy infrastructure: China, India and the Arabian Peninsula, according to researchers.
Duke University professor Michael Bergin set out to explore the link between air pollution and solar panel efficiency after a visit to India. 
"My colleagues in India were showing off some of their rooftop solar installations, and I was blown away by how dirty the panels were," Bergin said in a statement. 
Working with researchers at the Indian Institute of Technology-Gandhinagar and the University of Wisconsin at Madison, Bergin confirmed that solar panels become significantly less efficient as they become dirtier over time. 
Maintenance is key: the panels he examined showed a 50 percent uptick in in efficiency from being cleaned after several weeks. Cleaning solar panels is somewhat complex, and there’s a risk that cleaning them incorrectly could damage the expensive structures. 
Analyzing the panels at the Indian Institute of Technology-Gandhinagar, Bergin found they were covered in about 92 percent dust and 8 percent carbon and ion pollutants, particles from manmade pollution. 
That 8 percent is particularly dangerous, researchers said, as small particles from human-made pollution are extremely effective at blocking out light. 
In polluted environments, ambient particles in the surrounding air also block out sunlight and undercut solar panel efficiency.