When it comes to solar power, no one does it bigger and better than China. In 2016 alone, it doubled its solar energy production and there are no signs of this slowing down anytime soon. Unfortunately for China, along with some other Asian countries jumping on the solar bandwagon, they are getting haunted by their own recent past.
A new study published in Environmental Science & Technology Letters has found that air pollution is cutting solar energy output by up to 25 percent in certain parts of the world, particular in the smoggy and dusty lands of China, India, and the Arabian Peninsula. In Eastern US and Western Europe, air pollution could still cause a 3 to 15 percent reduction in efficiency depending on the exact locality.
The problem is tiny airborne pollutants and natural dust creating a grimy glaze on the solar panels, making it harder for the visible solar energy to transmit to the photovoltaic cells.
“The human-made particles are also small and sticky, making them much more difficult to clean off," Michael Bergin, professor of civil and environmental engineering at Duke University and lead author of the study, said in a statement. "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.”
Energy output is sliced in these Asian countries by 17 to 25 percent because of this grime, in spite of monthly cleaning of the panels. If the cleaning takes place only every two months, those numbers jump to 25 or 35 percent. The costs and manpower needed to carry out this spring cleaning are also a pretty big deal, considering China’s biggest solar farm – the 850-megawatt Longyangxia Dam Solar Park – is 27 square kilometers (10 square miles).
The grime is mainly made of natural dust (an average of 92 percent) along with carbon and ion pollutants from human activity. These smaller human-made particles are, however, more efficient at blocking out the light.
In a catch-22, this problem mainly affects areas that need to transition to green energy the most. Over the coming years, solar energy production is expected to boom even more rapidly in regions that experience high levels of dust and human-made particulate pollutants, notably the new industrial powerhouses of China and India. For the Arabian Peninsula, the problem is largely natural dust as opposed to human pollutants.
"China is already looking at tens of billions of dollars being lost each year, with more than 80 percent of that coming from losses due to pollution," said Bergin. "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."