Solar power production undercut by coal pollution
Regional differences
The researchers note that aerosols can also contribute to cloud formation, which also leads to additional losses. But the degree of this contribution is much harder to estimate, which is why researchers focus on aerosols for much of the analysis. Some of these aerosols occur naturally, usually from wind-blown dust in desert regions. However, despite deserts’ reputation as sunny paradises, the world as a whole has yet to build much desert solar infrastructure, so it’s not as big a factor as one might expect.
Coal appears to be a major contributor. Sulfur dioxide aerosols, mainly produced by coal combustion, are estimated to account for almost half of the aerosols analyzed here. Carbon-rich materials, which also typically come from fossil fuels, make up another 18%.
The impact of aerosols, however, is not uniformly distributed. In China, researchers estimated that aerosols reduced solar output overall by 7.7 percent and offset between a third and half of its annual growth. The researchers note that “the spatial distribution of China’s photovoltaic losses mirrors that of its coal-fired power capacity,” and an analysis of pollution data from China shows that 30% of aerosol losses can be attributed to coal burning.
In contrast, most solar generation in the United States takes place in the South and West, while coal-fired plants are more common in the East and Northeast. As a result, annual losses in the United States were less than half those recorded in China (3%).
The good news is that things are improving in China. In response to serious pollution problems, the country has built a new generation of high-efficiency coal-fired power plants and decommissioned some of the biggest polluters. And data shows it also benefits solar power, with the impact of aerosols declining in recent years.
Even with these improvements, it is striking that coal appears to be the only energy source that actively reduces the productivity of what is shaping up to be its main competitor. This should also incentivize a quicker shift away from coal, as at least part of the loss of coal generation will be offset by increased productivity from solar power.
Nature sustainability, 2026. DOI: 10.1038/s41893-026-01836-5
