Microbial Contribution to Soiling and Its Impact on Photovoltaic Module Soiling in Arid Zones of the Atacama Desert

Abstract

Soiling is one of the main challenges that affect the long-term performance of photovoltaic systems, especially in hyper-arid environments. Although the impact of mineral dust and atmospheric aerosols is well understood, the contribution of microbial communities to soiling accumulation and optical losses is not. This study investigates the biological mechanisms underlying the formation of biofilms on photovoltaic glass surfaces in the Atacama desert, one of the most irradiated regions. Using a combination of microbiological, metagenomic, morphological and chromatographic analyses, we demonstrate that bacterial strains isolated from the genera Arthrobacter, Dietzia, and Kocuria within soiling layers exhibit remarkable tolerance to high UV radiation and desiccation. Biofilm-forming taxa are identified, including Bacillus, Sporosarcina, Bhargavaea, Mesobacillus, Cytobacillus, Planococcus, Peribacillus, and Kocuria. Dietzia maris and D. kunjamensis subsp. schimae, are found to synthesize photoprotective carotenoids, with spectral features consistent with lutein-like compounds or related xanthophylls, which may interfere with photovoltaic performance optically. Field emission scanning electron microscopy imaging confirmed the formation of extracellular polymeric matrices capable of encapsulating cells and mineral particles, thereby enhancing surface adhesion and reducing the efficiency of cleaning processes. Current–voltage curve measurements revealed short-circuit current losses of up to 30.66% in colonized samples, highlighting the significant impact of microbial biofilms on energy output. These findings emphasize the importance of incorporating biological variables into soiling models and mitigation strategies, especially in regions with high solar potential.