Air pollution takes a toll on solar energy

Haze and pollution can filter out sunlight and cut electricity production


By blocking sunlight and dirtying solar panels, air pollution — as seen here, in Shanghai, China in 2015 — can lower the production of electricity.


Air pollution can be a drag for solar energy. That pollution can cut the output of solar panels. And the energy losses from this are quite costly, a new study finds.

Dust and other air pollutants can produce a haze that darkens the sky. That haze then acts as a light filter. It cuts how much sunlight reaches solar-energy panels. Its effect on the electricity production by those solar collectors can be huge, the new study finds. It estimates that across parts of India, China and the Arabian Peninsula alone, pollution can slash electricity from solar energy by 17 to 25 percent.

Andhaze in the air isn’t the only factor that can limit how well solar panels work. If pollutant particles land on a panel’s flat surface, they will further block how much light gets through to the solar cells below. Dust can come from natural sources, such as windswept soils. But human activities produce much of these pollutants. Those activities include driving cars, powering factories and converting coal to electricity.

Michael Bergin works for the Pratt School of Engineering. It’s at Duke University in Durham, N.C. Bergin led a team that collected dust and pollution from solar panels in India. Then his group calculated how much this pollution could cut the solar energy output there, in China and in Mideast nations.

In India, polluted air appears to cut solar electricity by roughly 1 gigawatt (or billion watts). Natural dust and human-generated pollution contribute about equally here.

In eastern China, fossil-fuel use contributes far more than does natural dust. China also generates more solar energy than any other country. So there, air pollution’s toll is much bigger. It likely cuts electricity production by close to 11 gigawatts, the researchers calculate. That’s the full power output of 50.6 million photovoltaic solar panels. It’s also equal to 5,500 large-scale wind turbines or 1,100 coal-fired power plants. And it’s the amount of energy needed to power 1.1 billion LED lightbulbs. Clearly, that’s a lot of energy being lost.

It’s also costly. Making up for that lost energy is costing China the equivalent of about $10 billion per year, Bergin notes. Regular cleaning of solar panels can help. Cleaning the air, he notes, will prove a lot harder.

His team describes how it came to these numbers August 8 in Environmental Science & Technology Letters.

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