Coal plants persist as a large barrier to the global solar energy transition

Abstract The global energy transition depends on solar photovoltaic (PV) power displacing fossil fuels to deliver projected climate and air quality benefits. However, aerosol pollution from co-located coal plants actively suppresses PV energy production. Here a global, facility-level dataset shows that aerosols reduced global PV generation by 5.8% in 2023 (111 TWh). From 2017 to 2023, annual aerosol-induced PV energy losses from existing systems were, on average, equivalent to one-third of the energy added by new PV installations. In China, aerosols caused the largest PV energy losses worldwide, reducing national PV generation by 7.7% in 2023. The corresponding annual loss-to-growth ratio averaged 38% and frequently exceeded 50%. Despite continued coal expansion, PV energy losses have declined by 1.4% yr −1 since 2017 owing to stricter emission controls. By contrast, the USA, where co-location of solar and coal plants is limited, experienced only 3.1% aerosol-induced PV loss. Given the slow pace of global coal phase-out, these results reveal a constraint on solar performance that, if unaccounted for, could lead to a systematic overestimation of the transition’s contribution to climate and air quality goals.