In a recent research article published in the journal Nature Sustainability, researchers reveal how aerosol pollution from coal-fired power plants significantly reduces solar photovoltaic energy generation, posing a critical barrier to the clean energy transition.
Study: Coal plants persist as a large barrier to the global solar energy transition. Image Credit: Sina Ettmer Photography/Shutterstock.com
Coal-Aerosol Impact on Solar Energy Generation
Solar photovoltaic (PV) systems have expanded dramatically in the last decade, becoming the most economically attractive source of new electricity generation. Development has been fueled by improvements in module materials and manufacturing, combined with supportive policies that ensure competitive pricing.
While hydropower and other renewable sources face geographic and environmental limits, solar energy generally offers scalable deployment with fewer constraints. These advancements have transformed solar into a leading solution for decarbonizing electric grids and reducing air pollutants such as sulfur dioxide and nitrogen oxides.
However, the co-location of PV installations with coal plants presents a paradox. Coal plants emit sulfur dioxide (SO2), nitrogen oxides (NOx), and large quantities of particulate matter, which form aerosols that scatter and absorb sunlight before it can reach solar panels. This "solar dimming" effect suppresses the overall solar energy productivity. In some countries, especially China, the severity of air pollution exacerbates these losses. Previous studies have hinted at this issue but lacked a global, facility-level assessment that integrates detailed solar installation data with atmospheric conditions, which this paper addresses.
Global PV Loss Quantification
To evaluate aerosol impacts on solar power generation, the authors constructed a global database of over 140,000 PV facilities by integrating multiple datasets, including satellite imagery, crowdsourced geographic information, and machine-learning-based PV detection algorithms.
They deployed a three-step approach:
- Identifying candidate solar sites
- Using advanced image segmentation techniques to delineate the exact location and extent of solar panels
- Integrating this data with atmospheric reanalysis products
High-resolution satellite imagery was used to accurately map solar panel arrays, avoiding overestimation by excluding non-panel areas. Aerosol and cloud optical properties were derived from reanalysis datasets to simulate the solar irradiance attenuated by atmospheric particles.
This enabled facility-level simulations of hourly PV electricity output, both with and without aerosol impacts, isolating the portion of energy loss attributable to pollutant aerosols.
Chemical transport modeling was applied to attribute aerosol concentrations specifically to coal-fired power emissions. The study also incorporated time-series analyses to assess trends over a decade, alongside cross-referencing emission control policies and coal fleet modernization efforts, particularly in China, to contextualize observed changes.
Coal-Solar Spatial Interaction
The study reveals that aerosols from coal plants reduced global solar PV generation by approximately 5.8% (about 111 TWh) in 2023. This loss equates to roughly one-third of the energy gained from new solar installations annually, indicating that pollution is negating a significant fraction of solar growth potential worldwide.
China experiences the most pronounced effect, with a 7.7% decrease in solar output, primarily driven by coal-related sulfur and carbonaceous aerosols, while losses are notably lower in countries like the US, where coal and solar facilities are less co-located.
Despite China's increased coal electricity production, stringent emission standards and retrofit programs have led to consistent reductions in harmful atmospheric pollutants affecting solar sites, resulting in a year-over-year decline of about 1.4% in aerosol-induced PV losses since 2017.
This paradoxical trend highlights how technological improvements and regulatory enforcement can partially mitigate pollution-related solar losses, even without a coal power phase-out. In contrast, other regions, including India, show stagnation or slight increases in aerosol impacts because of less stringent controls.
Geospatial analysis confirms the strong correlation between solar generation losses and proximity to coal-fired power plants. Although dust and natural sources contribute in desert regions, their overall impact is smaller compared to coal-related aerosols.
The results highlight a complex dynamic in which the growth of solar capacity is partially offset by pollution from fossil-fuel infrastructure, suggesting that co-optimization of energy expansion and pollution control is essential to maximize sustainable electricity output.
Moreover, the findings caution against overestimating the climate and health benefits of solar growth without considering pollution-induced efficiency losses.
Implications for Clean Energy
The research highlights a critical interface between fossil fuel pollution and renewable energy performance, demonstrating that aerosols emitted by coal-fired power generation significantly curtail solar PV productivity on a global scale.
China's experience illustrates that emission controls and modernization of coal infrastructure can reduce but not eliminate this effect. The persistence of coal plants worldwide indicates that environmental gains from solar energy may be systematically overvalued if aerosol losses are ignored.
Effective strategies for accelerating the clean energy transition must therefore incorporate rigorous pollution mitigation, especially targeting coal emissions, alongside expanded solar deployment. This integrated approach can ensure that the full benefits of solar energy are realized, supporting the achievement of international climate and air quality goals.
Future policies should recognize the interdependence between fossil fuel phase-down efforts and the efficiency of renewable energy systems to avoid undermining progress toward a low-carbon energy future.
Journal Reference
Song R., Yin F., et al. (2026). Coal plants persist as a large barrier to the global solar energy transition. Nature Sustainability. DOI: 10.1038/s41893-026-01836-5, https://www.nature.com/articles/s41893-026-01836-5