Coal Emissions Cut Global Solar Output by 5.8%, Equal to 18 Coal Plants' Yearly Generation

TL;DR: Atmospheric aerosols from coal pollution cut global solar electricity output by 5.8% in 2023, equal to the yearly generation of 18 medium‑sized coal plants. China’s solar output fell 7.7% due to the same effect.

A new study published in Nature Sustainability shows that particulate matter from coal‑fired plants acts as a hidden drag on solar panels by scattering and absorbing sunlight. Researchers from the University of Oxford and University College London used satellite imagery to track more than 140,000 solar installations worldwide and combined those images with ground‑based aerosol measurements to estimate how much light is lost before it reaches photovoltaic cells.

The team mapped the spatial distribution of fine particles over a six‑year period (2017‑2023) and calculated the reduction in solar irradiance for each installation. By converting irradiance loss into electricity loss using typical panel efficiencies, they derived a global figure for 2023.

The analysis found that atmospheric aerosols reduced global solar electricity generation by 5.8% in 2023, a loss of 111 terawatt‑hours. That amount matches the annual output of about 18 medium‑sized coal‑fired power plants. In China, the world’s largest solar producer, output dropped by 7.7% because of pollution, with roughly 29% of that decline traced directly to coal‑related emissions.

These pollution‑induced losses offset nearly one‑third of the yearly gains from new solar capacity added between 2017 and 2023, suggesting that the effectiveness of the energy transition may be overstated if air quality is ignored. While China’s solar clarity has improved by about 1.4% per year over the last decade thanks to tighter emission rules, the global trend shows that coal‑related aerosols remain a significant barrier to maximizing renewable output.

Ignoring this hidden drag could lead governments to overestimate progress toward climate targets and misallocate investment in renewable infrastructure. Policymakers should therefore consider joint strategies that curb coal emissions while expanding solar farms, ensuring that gains in installed capacity translate into actual electricity generation.

Watch for upcoming policy shifts that target coal subsidies and for updated satellite‑based aerosol monitoring, which will determine whether air‑quality measures can close the gap between installed solar capacity and actual electricity generation.