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Sun Block: How Pollution Is A Drain On Solar Energy Production

Courtesy of Mike Bergin
Duke Professor Mike Bergin (left), Chinmay Ghoroi (right), a professor at IIT Gandhinagar, and a member of the ITT staff stand near solar panels in Ahmedabad, India. The writing on the panel shows how dirty they are.

Solar power is one of the fastest growing energy sources in the world. Whether from massive utility-scale solar farms or residential rooftop panels, you can expect to see more solar in the future.

But scientists have identified something that can really hurt the performance of those panels: air pollution.

The story of this discovery could start a lot of different places; the Taj Mahal in India is as good a place as any. That’s where, seven years ago, Mike Bergin, a professor at Duke, noticed something a little off.

“We’re looking at the Taj Mahal and there’s a clean white section … and then a bunch of scaffolding up and a section that’s really brown,” he says. “I asked [my companions] what’s going on and they said, 'Oh, we have to clean the Taj Mahal once every few years.'”

Since Bergin is an environmental engineer, he decided to figure out what was discoloring the mausoleum.

“We did a study and we measured what was depositing. We measured what was in the air," he says. “We showed how sun gets blocked when particles get deposited on  the surface.”

Not surprisingly, dust and pollution particles covered the surface. Fast forward to a more recent visit to India, and Bergin and his colleagues noticed the same thing on solar panels.

That got him wondering what kind of impact pollution was having on power generation.

“We did a study in Northwest India, where every few weeks they’d clean the solar panels," Bergin says. "And, of course, the power generation would almost double instantly when they cleaned them."

Using that information, and environmental data from around the world, Bergin now thinks researchers can show how much solar is being lost to air pollution. In extreme cases, he thinks it can cut electricity production by 25 percent.

He says one of the things that most surprises him is how little research has been done about it.

“The people who are in the solar industry say, ‘Oh, of course that’s happening,’” Bergin says. “People who have solar panels at their houses or anywhere say, ‘Oh yeah, of course, I know that. Doesn’t everybody know that this is what's going on?’”

A quick call to a solar panel installation company confirmed that sentiment.

“Absolutely, I think this one falls under common sense,” says JP Novak, owner of 512 Solar, a solar-panel installation company in Austin.

One of the services his company offers is cleaning panels, especially in the spring when they get coated with a thick layer of pollen.

“We want to get that off so we can fully utilize the maximum amount of sunlight that we have here in Austin, Texas,” Novak says.

Bergin says of all the particles that can hurt solar production, manmade pollution seems to do the most damage. It’s harder to clean and absorbs more solar energy than dust particles.

He thinks his research could help us understand the wider economic effects of air pollution.  

“The main thing we have to do is figure out how to lower the emissions of these key pollutants,” he says.

One suggestion for doing that: install solar panels on your house.

Mose Buchele focuses on energy and environmental reporting at KUT. Got a tip? Email him at Follow him on Twitter @mosebuchele.
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