Are Solar panels still effective in places like China with very bad ‘brown’ air pollution? [Ray M.]

From inefficient grids, shortfalls in policy, and even the occasional eclipse, solar-energy collection faces no shortage of hurdles. Scientists have discovered another stumbling block: air pollution. In certain parts of the globe, the accumulation of particulate matter on solar panels can curtail energy output by more than 25 percent, according to a new study.

Published last week in the journal Environmental Science & Technology Letters, the study revealed that the regions most susceptible to this challenge also have the heaviest solar investments. These regions include China, India and the Arabian Peninsula.

Working with his counterparts at the Indian Institute of Technology-Gandhinagar, Bergin measured the efficiency of the school’s photovoltaic solar panels as they thickened with grime over several months. Although this latter group contributed a smaller percentage of the overall grime on the solar panels, it can result in greater energy loss, Bergin said. “The man-made particles are also small and sticky, making them much more difficult to clean off,” he said. In addition, smaller particles block sunlight more efficiently than natural dust does, he added.

In certain swaths of China, where pollution has a stranglehold, human-made particles can spell losses of tens of billions of dollars every year due to solar-energy-collection dips, Bergin said.