Researchers led an international collaborative effort to identify and quantify the impact of microbes as an underappreciated potential threat to solar energy production in the world's driest (non-polar) desert. Recent results show an overall decrease of up to 30.66% in short-circuit current under the influence of the biofilm-forming microorganisms found colonizing photovoltaic panel surfaces in the Atacama Desert. This has implications that solar installations may be reducing their expected energy yield by nearly one-third because they have reduced their current yield at short-circuit points.
Evaluation of microbial contributions to solar panel "soiling" and their subsequent effect on energy yield through decreased operational efficiency (as discussed in "Microbial Contribution to Soiling and Its Impact On Photovoltaic Module Soiling Within Extreme Environments in Arid Regions of the Atacama Desert") is the first study of its kind to assess the impact of microbial communities on the adhesion and persistence of dust coatings on solar panels in extreme environments.
From Inorganic Dust to Living Crusts
Conventional understanding of solar panel soiling has long focused on the accumulation of inorganic mineral dust particles. However, this study shifts the paradigm by demonstrating that microbial life - particularly bacteria from the genera Arthrobacter, Dietzia, and Kocuria - actively colonize panel surfaces and produce robust biofilms that dramatically alter the properties of dust deposits.
These microorganisms produce extracellular polymeric substances, or EPS - a sticky matrix composed of approximately 65 percent polysaccharides, 25 percent peptides and 10 percent lipids. Over a 72-hour growth period, researchers observed EPS thickness expanding from 0.2 to 0.8 micrometers. Under field-emission scanning electron microscopy, these biofilms appear as dense, three-dimensional networks that encapsulate both microbial cells and mineral particles, effectively cementing dust layers onto panel surfaces and making them far more resistant to removal.
Photoprotective Pigments That Interfere With Light Capture
In a striking evolutionary twist, the study also identified carotenoid pigments - specifically lutein-like compounds and related xanthophylls - produced by Dietzia strains. These pigments help the bacteria survive the Atacama Desert's extreme ultraviolet radiation, which reaches daily intensities of approximately 3.5 kilowatts per square meter.
Crucially, these photoprotective compounds absorb light across spectral ranges that overlap with the conversion window of monocrystalline silicon photovoltaic modules. This overlap suggests an additional mechanism of optical interference, wherein the very pigments that help bacteria endure the desert sun also compete with solar cells for incoming photons.
Laboratory Tests Reveal Substantial Electrical Losses
To quantify the performance impact of microbial biofilms, the researchers conducted accelerated colonization tests on photovoltaic glass samples under controlled laboratory conditions. The results were striking: after just seven days of biofilm development, samples from the University of Antofagasta showed short-circuit current losses ranging from 15.20 percent to 30.66 percent. Samples from the Atacama Desert Solar Platform exhibited losses between 11.01 percent and 20.12 percent.
However, the study's corresponding author, Aitor Marzo of the University of Granada, was careful to contextualize these figures. "These tests were designed as accelerated experiments to reproduce the initial stages of biofilm adhesion and consolidation within a limited laboratory timeframe," he explained. "The maximum losses observed represent an upper bound of biological impact and should not be directly interpreted as typical field values." Under real-world conditions, Marzo noted, colonization occurs more gradually and is influenced by environmental factors such as irradiance, humidity, dust deposition and nutrient availability.
A Challenge for Conventional Cleaning Protocols
Perhaps even more concerning than the immediate performance losses is the discovery that conventional cleaning methods may be ineffective against mature biofilms. The study found that increased EPS deposition enhances cohesion within the biofilm structure, reducing the efficacy of standard cleaning techniques such as dry brushing and water rinsing.
"Microorganisms are not a passive component of soiling, but active agents that contribute to deposit consolidation, reduce optical transmittance and decrease the effectiveness of conventional cleaning methods," the authors wrote.
Global Solar Expansion Amplifies the Issue
The findings come at a critical juncture for the global solar industry. According to the International Energy Agency, renewable electricity generation is expected to rise by roughly 1,050 terawatt-hours annually through 2030, with solar photovoltaics accounting for more than 600 terawatt-hours of that growth each year. In 2025 alone, growth in global electricity generation from solar photovoltaics reached a record 620 terawatt-hours, the largest year-on-year increase ever recorded.
Much of this expansion is occurring in high-irradiation regions, including the world's deserts. The Atacama Desert, where this study was conducted, receives approximately 6,800 hours of equivalent solar irradiation annually, making it one of the most promising locations for solar energy development anywhere on Earth - but also one of the most challenging in terms of panel maintenance.
Future Research and Potential Solutions
The research team emphasized that their findings underscore the urgent need to incorporate biological factors into soiling prediction models and photovoltaic system mitigation strategies for arid regions. "Our work shows that microbial communities isolated from photovoltaic modules in the Atacama Desert exhibit a high tolerance to desiccation and extreme irradiance," Marzo told pv magazine.
At the same time, the pigmented Dietzia strains identified in the study may open unexpected avenues for technological innovation. "These pigments present potential biotechnological applications in coatings and self-cleaning technologies," the authors noted, suggesting that the very organisms causing the problem might also inform the development of its solution.
Industry efforts are already underway to address microbial soiling through advanced materials. Australian nanotechnology company Nanoveu, for instance, has developed a hydrophilic self-cleaning nano-coating designed to inhibit biofilm formation and algae growth on solar panels, while other research groups are exploring superhydrophobic coatings that could provide both self-cleaning properties and optical transparency.
The study was conducted by researchers from the University of Granada in Spain and the University of Atacama in Chile, with findings accessible in the July 2025 issue of Advanced Sustainable Systems.
