Researchers studying PV panels in Chile’s extremely dry Atacama Desert found that cemented pollution can cause up to 9.8% annual energy loss. Their combined field and laboratory work shows that dry cleaning leaves behind residue that accelerates future cementation, making wet cleaning the more effective long-term strategy, despite higher costs and scarce water.
An international research team has investigated the formation of cemented pollution on PV panels operating in the hyper-arid conditions of the region with the world’s highest solar radiation levels, the Atacama Desert in northern Chile, and found that annual energy losses, if left unchecked, could be as high as 9.8%.
The novelty of the research work consisted in shifting the focus from analyzing the impact of uncemented dust on PV performance to cemented pollution, which the scientists described as a factor of increasing relevance in hyper-arid environments.
The difference between the two types of contamination is determined by the stronger or weaker bond with the module surface. Cemented dirt adheres to moisture, organic matter or chemical reactions and is difficult to remove with simple rain or light cleaning, while non-cemented dirt is usually formed by dust, sand or light dirt and is easily washed away by rain or mild cleaning.
“The novelty of this study lies in its integrated approach: it combines long-term real-field monitoring in the Atacama Desert, one of the most extreme PV exposure environments in the world, with accelerated laboratory experiments that replicate cementation processes under controlled conditions,” the research team explained.
The outdoor tests were carried out on the Atacama Desert Solar Platform (PSDA) run by the Antofagasta Center for Energetic Development (CDEA) at the University of Antofagasta (UA), while the indoor pollution tests were carried out in a laboratory of the French National Institute of Solar Energy (INES) – a department of the French Commission for Alternative Energy and Atomic Energy (CEA).
Image: Universidad de Antofagasta, Renewable Energy, CC BY 4.0
For the outdoor tests, the scientists used north-oriented PV glass coupons measuring 4 cm x 6 cm, mounted in triplicate on active PV modules with a tilt angle of 20°. Several samples were removed and analyzed after 2 days, 1 week, 1, 2 and 3 months, with contamination characteristics assessed through morphological, elemental and structural analyses.
The PV performance was measured with two calibrated Si reference photocells (Si-V-10TC-T) installed at the same tilt angle and orientation as the benchmark modules. One reference cell was cleaned daily, while the other remained uncleaned.
They also conducted a techno-economic analysis to estimate pollution-related losses and the cost-effectiveness of cleaning, assuming the operation of a 1 MW PV plant using monofacial crystalline silicon technology.
For the indoor tests, the researchers used a modified climate chamber to monitor temperature and relative humidity, as well as data loggers for monitoring the PV system. Artificial pollution was generated via a dust dispenser, where the PV glass samples and mini modules were mounted on a tilting plate that was heated and cooled to reproduce realistic slopes.
Image: Universidad de Antofagasta, Renewable Energy, CC BY 4.0
The outdoor analysis showed that, under a linear accumulation model, pollution can reduce energy output in the simulated power plant by as much as 9.8% or $93,800 per MW per year.
The indoor tests have shown that dry cleaning is effective in restoring the original performance of the PV module, although the cemented particles are not completely removed, leaving residues that act as crystallization nuclei.
“These residual traces promote new cementation cycles under favorable environmental conditions, increasing material adhesion in subsequent events,” the scientists explained. “This cumulative effect complicates future maintenance tasks and reinforces the need to select cleaning strategies that restore optical performance and minimize nucleation and deposit evolution over time.”
They also emphasized that wet cleaning is preferable despite higher operational costs and low water availability in the region.
Their findings are available in the study “Pollution in the Atacama Desert: impact on solar performance and evaluation of cleaning techniques”, published in Renewable energy. The research group consisted of scientists from the Chilean Corporación Atamostec, the Spanish University of Granada and the Université Grenoble Alpes in France.
“These findings extend beyond the Atacama context and provide a transferable methodology for studying and reducing cementation-induced pollution in other arid and semiarid areas,” they concluded.
Atacama has become the largest solar energy hub in Chile and Latin America, with dozens of large-scale solar power plants coming online there in the past decade. The country has exceptional conditions for solar energy production, and in fact the installed solar energy capacity in this region represents more than 90% of the total installed capacity in Chile.
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