Soiling in the Atacama Desert: Impacts on solar performance and evaluation of cleaning techniques

Cemented soiling on photovoltaic modules poses a critical challenge to energy yield in arid and hyper-arid climates. Unlike loose dust, these hardened deposits form cohesive crusts that impair optical transmittance and accelerate surface degradation. This study combines outdoor exposure in the Atacama Desert with controlled laboratory replication to investigate the formation, evolution, and impact of cemented soiling on PV systems. Moving beyond previous research focused on loose particles, we highlight the role of gypsum recrystallization, quantify associated energy losses, and evaluate cleaning strategies in terms of recovery efficiency and long-term prevention. The dual methodology, real-world exposure and accelerated testing with desert dust, enables reproducible insights into cementation kinetics and cleaning effectiveness. Cementation began as early as day two, forming structured gypsum crystals by day seven. Transmittance losses stabilized at –0.827% per month, resulting in estimated annual losses of ∼98 MWh per 10 MW plant (∼9.8%). Cleaning tests showed that water-based methods restored 99.9% of the initial performance after one application, while dry methods restored 98.8% but left residues that promoted recrystallization. These findings offer actionable insights to optimize cleaning frequency and methods, supporting more efficient and sustainable PV operations in desert environments.