Dust accumulation, often referred to as dust accumulation or soiling, is one of the major problems affecting the performance of solar power plants, whether they use photovoltaic (PV) technologies or concentrated solar power (CSP) systems. This phenomenon is particularly critical in arid and semi-arid regions, where climatic conditions favor the continuous deposition of fine particles, sand, and dust on optical surfaces. In the context of the energy transition, where these plants are increasingly integrated into green hydrogen production systems, yield losses linked to soiling are not limited to a simple drop in electricity production, but directly affect the entire downstream energy chain, particularly electrolysis systems.
In monofacial photovoltaic technologies, the impact of dust is particularly direct and significant. These panels capture light only on their front face, meaning that any obstruction of this surface immediately reduces incoming light flux and therefore the generated current. Progressive dust accumulation can lead to a significant drop in energy yield, potentially reaching critical levels in desert environments if regular cleaning is not performed. This high sensitivity makes monofacial installations heavily dependent on effective maintenance strategies, particularly regarding cleaning frequency and methods.
Bifacial photovoltaic systems exhibit a different dynamic with respect to soiling. In addition to capturing light on their front side, they also harness reflected light on their rear side, which in theory allows them to partially compensate for losses due to soiling. However, dust affects not only the panel surface but also the surrounding ground, reducing albedo and thus the amount of light reflected toward the rear side. Consequently, even though bifacial panels offer greater overall resilience, their performance remains strongly dependent on soiling conditions and the cleanliness of their immediate environment.
In the case of concentrated solar power (CSP) plants, the impact of soiling is even more critical due to the very nature of the technology. CSP systems rely on mirrors or reflective surfaces that concentrate solar radiation onto a thermal receiver. Any reduction in reflectivity, even slight, leads to a significant drop in energy concentration, thereby reducing the temperature of the heat transfer fluid and the overall efficiency of the thermodynamic cycle. Unlike PV systems, where the loss is mainly electrical, CSP systems suffer a cascading degradation that directly affects heat production and therefore electricity conversion. This makes CSP extremely sensitive to dust deposition and requires regular and rigorous maintenance.
Cleaning strategies therefore play a central role in mitigating soiling-related losses. Several approaches exist, ranging from traditional manual cleaning to mechanized or robotic systems, as well as dry-cleaning techniques adapted to water-scarce environments. Manual cleaning, while simple and relatively low-cost in terms of investment, has important limitations in water consumption and labor requirements. Automated solutions, on the other hand, enable more precise optimization of cleaning frequency and reduced long-term operational costs, particularly in large-scale installations. In addition, anti-soiling coatings designed to reduce particle adhesion on surfaces represent a complementary solution, although they cannot completely eliminate the need for cleaning.
The impact of these phenomena on green hydrogen production is fundamental. In Power-to-Hydrogen systems, electricity generated by solar plants is used to power electrolyzers that split water into hydrogen and oxygen. Any reduction in solar power output therefore directly translates into a reduction in the amount of electricity available for electrolysis, leading to a proportional decrease in hydrogen production. Moreover, variability caused by soiling can affect the stability of energy supply, which may reduce the operational efficiency of electrolyzers, often designed to operate optimally under stable loads.
Overall, different solar technologies exhibit varying levels of sensitivity to dust accumulation. Monofacial PV systems are the most vulnerable, followed by bifacial PV systems, which benefit from some advantage due to their dual-sided design, while CSP systems, although highly efficient thermodynamically, remain very sensitive to any reduction in reflectivity. In all cases, soiling management appears to be a determining factor not only for the energy performance of solar plants but also for the economic and technical viability of green hydrogen production pathways.
Thus, optimizing cleaning strategies, combined with technological innovations such as anti-adhesive surfaces, automated cleaning systems, and artificial intelligence for maintenance scheduling, constitutes an essential lever for improving the overall performance of solar systems and maximizing their contribution to the global energy transition.