Beyond aerosol extinction: dominant indirect effects of Saharan dust on photovoltaic energy production in Central Europe

Saharan dust outbreaks are increasingly affecting Europe, yet their impact on photovoltaic (PV) energy production is still predominantly interpreted through the lens of direct aerosol radiative attenuation. This study demonstrates that such an approach substantially underestimates the other influence of dust on solar energy generation, as the dominant mechanism operates indirectly through dust-induced modifications of cirrus clouds.

We analyse six years (2019-2024) of national-scale PV generation data from Hungary, a Central European country where solar power accounted for approximately 25% of total electricity generation by 2024. PV production data are combined with reanalysis- and satellite-based atmospheric datasets, including dust column mass density from MERRA-2, cirrus cloud properties from MODIS, and surface irradiance from the CAMS Radiation Service. PV performance is quantified using a dynamically fitted production envelope, allowing generation losses to be assessed independently of capacity growth and seasonal variability.

Our results reveal that the largest PV yield reductions occur not during high-dust conditions alone, but when elevated dust loads coincide with enhanced cirrus cloud coverage and reflectance. Under such combined conditions, PV performance ratios fall to approximately 46%, compared to values exceeding 75% during low-dust, low-cirrus periods. During high-dust episodes, cirrus reflectance increases by about 55%, while cirrus coverage rises by 60-85%, providing clear observational evidence of strong aerosol-cloud interactions. Seasonal analysis shows that these indirect effects peak during the transitional seasons (spring and autumn), when thermodynamic conditions favour heterogeneous ice nucleation on mineral dust particles.

To disentangle direct and indirect pathways, we apply both linear and non-linear (quadratic) mediation frameworks, supported by block bootstrap resampling to ensure robust statistical inference. The bootstrap analysis consistently demonstrates that the indirect, cirrus-mediated pathway is statistically significant and more stable than the direct dust effect. While direct aerosol extinction can be strong during extreme dust events, its influence is episodic and highly state-dependent. In contrast, dust-induced cirrus enhancement represents a persistent and dominant mechanism governing PV efficiency losses across dust regimes.

These findings indicate that the radiative impact of Saharan dust on solar energy production is fundamentally a coupled dust-cirrus phenomenon rather than a simple aerosol-extinction problem. As the frequency and intensity of transcontinental dust intrusions are projected to increase under future climate conditions, explicitly accounting for aerosol-cloud interactions is essential for reliable PV performance assessment, energy planning, and the stability of increasingly solar-dominated power systems.

The research was supported by the Sustainable Development and Technologies National Programme of the Hungarian Academy of Sciences (FFT NP FTA) and NRDI projects TKP2021-NKTA-21 and RRF-2.3.1-21-2021.