According to a new study led by a team at Duke University, airborne particulate matter and dust are cutting solar photovoltaic energy output by more than 25% in certain parts of the world, with roughly equal contributions from ambient PM and PM deposited on photovoltaic surfaces. The regions hardest hit are also those investing the most in solar energy installations: China, India and the Arabian Peninsula. An open-access paper on the study appears in the ACS journal Environmental Science & Technology Letters.
With colleagues at the Indian Institute of Technology-Gandhinagar (IITGN) and the University of Wisconsin at Madison, Michael Bergin, professor of civil and environmental engineering at Duke University and lead author of the study, measured the decrease in solar energy gathered by the IITGN’s solar panels as they became dirtier over time. The data showed a 50% jump in efficiency each time the panels were cleaned after being left alone for several weeks.
The researchers also sampled the grime to analyze its composition, revealing that 92% was dust while the remaining fraction was composed of carbon and ion pollutants from human activity. While this may sound like a small amount, light is blocked more efficiently by smaller man-made particles than by natural dust. As a result, the human contributions to energy loss are much greater than those from dust, making the two sources roughly equal antagonists in this case. . . .
The resulting calculations estimate the total loss of solar energy production in every part of the world. While the United States has relatively little migratory dust, more arid regions such as the Arabian Peninsula, Northern India and Eastern China are looking at heavy losses—17 to 25% or more, assuming monthly cleanings. If cleanings take place every two months, those numbers jump to 25 or 35%. . . .
The Arabian Peninsula loses much more solar power to dust than it does manmade pollutants, Bergin said. But the reverse is true for regions of China, and regions of India are not far behind. . . .