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Photovoltaic solar plants are key to the energy transition, but the accumulation of dust, pollen, and other debris on panels seriously threatens their performance. New cleaning and maintenance technologies are emerging as solutions to this operational challenge.
Across the vast fields where solar parks stretch for kilometers, cleanliness might seem like a minor concern compared to the visual impact of thousands of gleaming panels. But the reality is more complex. Dirt in the form of dust, sand, bird droppings, pollen, or even industrial residues can cause energy production losses ranging from 2% to 40%, depending on the environment. Added to this is the unavoidable phenomenon of material degradation, which gradually reduces the efficiency of installations year after year.
At a time when every kilowatt counts toward meeting global climate goals, the impact of soiling has become a critical issue for companies responsible for operating and maintaining these infrastructures.
Silent Enemy: Soiling
The term soiling refers to the accumulation of particles on the surface of solar panels, partially blocking sunlight and decreasing photovoltaic conversion efficiency. Despite seeming like a simple issue, its complexity is enormous.
According to a study by the U.S. National Renewable Energy Laboratory (NREL), losses due to soiling represent one of the main causes of unplanned underperformance in solar plants—especially in arid, agricultural, or industrial regions.
“In areas like southern Spain, northern Chile, or the Middle East, dust can reduce efficiency by up to 30% if panels aren’t cleaned regularly,” says Nuria López, an O&M engineer working for an operator in Andalusia. “But even in humid regions, pollen or industrial pollution can form opaque layers that are difficult to remove.”
Degradation: A Persistent Threat
Unlike soiling, which can be resolved with proper cleaning, photovoltaic module degradation is irreversible. Panels lose performance over time—a typical degradation rate ranges from 0.5% to 0.8% annually—though this varies depending on material quality, installation practices, and environmental conditions.
The issue becomes more serious when degradation affects critical components such as inverters, cables, or connectors, which can cause partial or complete failures in specific module strings.
“A modern O&M strategy cannot be limited to just panel cleaning. It must include detailed degradation analysis using thermal inspections, electroluminescence techniques, or drones equipped with advanced sensors,” explains Santiago Morales, technical director at a solar maintenance company.
Technology to the Rescue
To combat efficiency loss caused by soiling, recent years have seen the emergence of technologies that automate and optimize cleaning. Among them are autonomous cleaning robots, dry-cleaning systems, and even dust-repellent nanocoatings.
One of the pioneers in solar robotics, Israeli company Ecoppia, has deployed more than 10 million automated cleanings in desert climates using robots that require neither water nor human intervention. “The future of solar O&M is autonomy. Robots that clean every night, without interrupting production, increase efficiency without raising operating costs,” says a company spokesperson.
In Spain, some firms are already integrating drones with computer vision to detect areas with higher dirt accumulation, optimizing the cleaning frequency by zones and reducing resource use.
How Much Does Not Cleaning Cost?
Frequent cleaning also has a financial angle: not cleaning may be more expensive than cleaning. According to SolarPower Europe, economic losses due to soiling in a 50 MW solar park can reach €500,000 annually if proper maintenance practices are not implemented.
“Even a short delay in cleaning after a sandstorm can lead to days of production loss. When multiplied across hundreds of installations, the impact is enormous,” says Irene García, a planning manager at a solar O&M services company in Extremadura.
This has led to a more data-driven maintenance approach, where technical teams use predictive models based on weather, humidity, soil type, and historical performance to plan “smart” cleanings only when necessary, instead of sticking to fixed schedules.
Toward Smart and Sustainable Maintenance
Efficiency should not come at the expense of the environment. In an increasingly water-scarce world—particularly in regions such as North Africa or southern Spain—cleaning methods must adapt to responsible water use.
As a result, many companies are adopting dry-cleaning solutions or implementing closed-loop water filtration and reuse systems when water is necessary.
Additionally, data analytics is becoming an essential tool for extending the lifespan of components. Machine learning algorithms can predict when a panel is beginning to degrade faster than expected, alerting technicians to intervene before the damage becomes irreparable.
The Key Is Prevention
Experience shows that a comprehensive O&M strategy—combining constant monitoring, preventive maintenance, optimized cleaning, and degradation analysis—can significantly improve a solar plant’s performance.
“The industry can no longer afford to see maintenance as a cost. It’s an investment that guarantees the energy and financial return of the project over the long term,” Morales concludes.
Ultimately, as long as the sun continues to shine, solar plants will keep producing energy. But ensuring that energy is generated as efficiently as possible depends largely on how well two silent threats—dirt and degradation—are managed. .