Coal Pollution Reduces Global Solar Output by 5.8%, Study Finds

A new study published in Nature Sustainability reveals that aerosols from burning fossil fuels, particularly coal, reduced global solar power generation by 5.8 percent in 2023. This loss equates to approximately 111 terawatt-hours of electricity, comparable to the annual output of 18 medium-sized coal plants. Researchers from the University of Oxford and University College London highlight that the impact is most severe when solar facilities are located near coal-fired power plants, a common practice for grid access. In China, the world's largest solar and coal producer, aerosols cut photovoltaic output by 7.7 percent, with coal pollution responsible for nearly one-third of this decline. Significant reductions were also observed in India, the US, Japan, and Pakistan, where solar output dropped by 15.1 percent. The findings suggest that current climate progress models may overestimate the benefits of solar energy if coal pollution remains unchecked. While renewables surpassed coal in global electricity share in 2025, the study warns that co-locating solar farms with coal plants undermines their efficiency. Lead author Rui Song emphasizes the need to control coal emissions to accurately realize the climate advantages of the energy transition.