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Scientific Reports volume 16, Article number: 7615 (2026) Cite this article
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This study investigates the effectiveness of oleic acid-functionalized Al₂O₃ nanoparticle thin-film coatings in reducing dust-induced performance losses in photovoltaic (PV) systems. Coating performance was evaluated using spraying durations of 20, 40, and 80 s and oleic acid concentrations between 0.5% and 4.5%. Characterization results indicated that the optimal coating was obtained using a 40-second spraying time and a 1.5% oleic acid concentration, resulting in a 231 nm film thickness and a water contact angle of 75.47°, confirming improved surface properties. Laboratory experiments showed that the coated surfaces accumulated, on average, 6.9 mg/cm² less dust than uncoated ones, preventing 0.6–3.0% efficiency loss. A central composite design (CCD) approach was applied by considering temperature, relative humidity, wind speed, and initial dust load as environmental variables. Field tests performed under real outdoor conditions demonstrated that coated Mini-PV modules produced 0.5–0.8 W more daily energy compared to uncoated panels. However, environmental factors such as temperatures above 35 °C and the presence of hydrophobic pollutants reduced long-term coating effectiveness. Overall, the findings indicate that oleic acid-modified Al₂O₃ coatings may serve as a passive strategy for mitigating dust accumulation and enhancing PV panel performance under certain conditions.
Solar energy, a form of renewable energy, possesses significant potential due to its global accessibility and sustainability. Each year, the Earth receives approximately 1.5 quadrillion megawatts of solar energy. If just 0.1% of this energy were converted into electricity at 10% efficiency, it would supply nearly four times the current global electricity demand^1,2.
Driven by increasing energy demands and environmental commitments such as the Paris Climate Agreement, the adoption of renewable energy systems to replace fossil fuels has gained significant momentum. Photovoltaic (PV) systems, in particular, have emerged as a promising clean energy solution³. The rapid decline in PV installation costs has accelerated their deployment; for instance, Türkiye’s installed solar capacity doubled from 9.7 GW in July 2022 to over 19 GW by the end of 2024⁴. Nevertheless, despite technological advancements, the energy conversion efficiency of PV panels remains highly sensitive to environmental conditions⁵. The efficiency of PV modules is influenced by numerous factors, both controllable and uncontrollable. Dust is an uncontrollable environmental factor that varies with geographical location. Its accumulation on PV panel surfaces can cause physical degradation, reduce incident solar radiation, and increase panel temperature, leading to thermal stress and altered electrical characteristics that significantly decrease energy conversion efficiency⁶. Soiling has been identified as a major contributor to energy losses in PV systems, with airborne particles obstructing solar radiation absorption and transmission, resulting in average annual losses of about 7%^7,8,9,10. Notably, certain anti-reflective coatings have been shown to reduce surface soiling by up to 60%, depending on the installation site’s geographical conditions¹¹.
Recent research has increasingly focused on developing and evaluating anti-soiling strategies to enhance the performance and reliability of photovoltaic systems under real-world conditions¹². Consequently, many manufacturers are exploring the addition of anti-fouling or self-cleaning properties to PV module coatings¹³. The extent of soiling is influenced by factors such as the chemical and physical composition of dust, climatic conditions, panel tilt angle, and geographical location¹⁴. In particular, arid summers, intensive agricultural activities, and low precipitation contribute to elevated dust emissions and surface soiling¹⁵. Additionally, the structure, size, and concentration of dust particles play a significant role in determining the magnitude of energy loss in PV panels¹⁶. Traditionally, solar panels are cleaned with water; however, this method is often impractical in regions with limited water resources. Additionally, dew formation can cause dust particles to adhere more strongly to panel surfaces, reducing the effectiveness of conventional cleaning. Efficiency losses due to dust accumulation are particularly severe in desert and arid climates. Hossain et al.¹⁷ noted, dust composition varies significantly by region, highlighting the need to optimize antifouling coatings for specific geographical and climatic conditions. Huang et al.¹⁸ examined the comparative performance of coatings on surfaces with varying wettability, emphasizing the critical role of surface energy in dust retention. Wang et al.¹⁹ developed a bioinspired three-layer coating, modeled after the structure of human hair, which exhibited superhydrophobic properties, effectively reducing reflectance and increasing power output by up to 2.6%. Abdrabo et al.²⁰ demonstrated that nanoceramic sprays based on TiO₂ and SnO₂ offer a practical solution, enhancing photovoltaic efficiency by up to 5.4% under outdoor conditions. Shahzad et al.²¹ provided a comprehensive review of the effects of soiling on PV performance and evaluated both conventional and advanced cleaning strategies, including hydrophobic coating approaches. In a separate experimental study, Tayel et al.²² applied a PDMS/SiO₂-based hydrophobic nanocoating to PV panels and tested their performance under outdoor conditions for 40 days. Their results demonstrated that the nanocoated panel achieved a 30.7% higher efficiency compared to the uncoated reference panel. Shuhua et al.²³ demonstrated that PDMS coatings infused with inert silicone oil exhibit enhanced icephobic and anti-soiling behavior, maintaining reduced dust adhesion even after prolonged outdoor exposure. Abhinav et al.²⁴ developed HMDS-modified silica–zirconia composite coatings that showed high mechanical durability, stable hydrophobicity, and consistent anti-soiling performance under repeated abrasion cycles. These studies underscore that coating-based passive methods offer significant promise as cost-effective, durable, and high-performance alternatives to active cleaning systems.
Surface coatings used on PV cover glass are generally categorized as hydrophobic, hydrophilic, antireflective, or multifunctional anti-soiling layers. These coatings aim to reduce particle adhesion by lowering surface energy, modifying wetting behavior, or introducing micro/nanostructured textures on the glass surface²⁵. Recent studies have demonstrated that both hydrophobic and hydrophilic coating strategies can significantly reduce dust adhesion on PV surfaces. Hydrophobic approaches such as silicone-oil-infused PDMS coatings and HMDS-modified silica-zirconia hybrids have shown enhanced dust repellency and mechanical robustness under outdoor exposure²⁴. In contrast, hydrophilic strategies, including quantum-sized TiO₂ coatings, promote rapid water spreading and photoinduced self-cleaning, enabling effective removal of adhered particles during dew or rain events²⁶. Nature-inspired surfaces like the lotus leaf further illustrate how hierarchical structures contribute to long-term dust-repellent behavior²⁷. Recent studies have increasingly emphasized the importance of advanced coating technologies in mitigating dust accumulation and enhancing the optical performance of photovoltaic (PV) modules, particularly in arid and desert climates where soiling losses are most severe. Comprehensive reviews have highlighted the role of anti-soiling and anti-reflective coatings in improving long-term durability and energy yield under harsh environmental conditions²⁸, while emerging research on polymer-based functional coatings demonstrates the potential of superhydrophobic and antistatic surfaces for improved self-cleaning and dust mitigation²⁹. Field evaluations of hydrophobic and nanostructured coatings in dusty regions, including Oman, consistently report measurable gains in transmittance and electrical output, confirming their practical relevance^30,31. Furthermore, comparative studies examining superhydrophobic and superhydrophilic coatings provide valuable insights into how surface chemistry and wetting behavior influence dust adhesion mechanisms³². Collectively, this growing body of literature underscores the critical need for robust, multifunctional coatings capable of maintaining PV performance by reducing soiling effects and enhancing surface durability in real-world operating conditions³³.
In this study, we propose a novel approach to mitigating soiling-induced energy losses in PV panels by applying an oleic acid-modified Al₂O₃ nanoparticle thin film onto the outer glass surface using a spray-coating technique. The coated surfaces were characterized using SEM, AFM, and XRD analyses, and their anti-soiling performance was evaluated under both laboratory and real-world environmental conditions. This work aims to enhance sustainable and efficient energy production, particularly in arid regions where soiling presents a significant challenge. To the best of our knowledge, this study provides a new and distinctive contribution by exploring oleic acid-modified Al₂O₃ coatings for anti-soiling applications in PV technologies.
This section outlines the materials, synthesis procedures, surface characterization techniques, and performance testing protocols used to evaluate the effectiveness of oleic acid-functionalized Al₂O₃ nanoparticle coatings for anti-soiling applications in PV panels. The experimental workflow is summarized in Fig. 1.
Experimental workflow for evaluation of anti-soiling performance of oleic acid-Modified Al₂O₃ coatings in photovoltaic applications.
All chemicals utilised in this study were of analytical grade and were employed without further purification. The following reagents were procured from Sigma-Aldrich (USA) and Merck (Germany): aluminium isopropoxide (98%), nitric acid (≥ 65%), acetylacetone (≥ 99%), oleic acid (≥ 99%), hexane (≥ 95%), toluene (≥ 99.5%), and isopropyl alcohol (≥ 99.7%).
The alumina sol was prepared with minor modifications based on the procedure outlined by Wang et al.³⁴. The initial step involved the dissolution of 2.04 g of aluminum isopropoxide (C₃H₇O₃Al) in 100 mL of anhydrous isopropyl alcohol. Subsequently, 2 mL of concentrated nitric acid and 1.25 mL of acetylacetone were added. The mixture was stirred for 60 min at a temperature of 70–80 °C within an oil bath. The resultant solution was transparent and exhibited stability at ambient temperature over an extended duration. The Al₂O₃ thin films were deposited onto glass substrates via spray coating. During the deposition, the substrates were maintained at a constant temperature of 250 °C. After deposition, the films were cured at 500 °C for 1 h to enhance adhesion and film integrity. The thickness of the coatings was investigated parametrically by varying the spray time. Oleic acid functionalization was carried out following the method by Soleimani and Zamani³⁵, with some modifications. Oleic acid solutions at various concentrations (0.5 g/100 mL, 1.5 g/100 mL, and 5 g/100 mL) were prepared using hexane as the solvent. The coated glass samples were immersed in the solutions at 50 °C for 1 h. After immersion, the samples were removed, rinsed three times with toluene, and dried at 60 °C for 24 h. The effect of oleic acid concentration on the hydrophobicity of the surface was examined.
The morphology of the functionalized glass surfaces was characterized by scanning electron microscopy (SEM, JEOL JEM-2100). Additionally, atomic force microscopy (TT-2 AFM) was employed to evaluate surface roughness and topography. The crystalline structure of the films was investigated using X-ray diffraction (EUROPE 600 Benchtop XRD). Water contact angle measurements (DATAPHYSICS / OCA 50Micro) were performed to assess the hydrophobic or hydrophilic nature of the surfaces. Optical transmittance of the samples was measured using UV-Vis spectroscopy (Jenway 72 Series) and compared to that of untreated glass. Based on these characterizations, the samples exhibiting the highest hydrophobicity and light transmittance were selected for further soil (dust) accumulation tests.
Selected wettability-tuned glass samples were integrated into miniature photovoltaic modules using a conventional lamination process. The sandwich structure consisted of wettability-tuned glass / EVA (ethylene vinyl acetate) / solar cell / EVA / TPT (Tedlar polyester). Lamination was carried out using a custom-built laboratory laminator at a constant temperature of 135 ± 5 °C.
The fabricated test panels and two reference panels were subjected to both laboratory and outdoor performance evaluations. Laboratory tests involved controlled variation of temperature, relative humidity, soil concentration, and wind speed. A central composite design (CCD) approach was employed using Minitab statistical software to structure the experimental design. In this study, the CCD method was selected to optimize the coating parameters because it provides an efficient and statistically rigorous framework for modeling nonlinear relationships among continuous variables such as oleic acid concentration, spraying duration, and nanoparticle loading. Unlike simpler factorial or Taguchi designs, CCD incorporates axial points that enable the estimation of curvature effects and second-order interactions, allowing the construction of an accurate quadratic response surface with fewer experimental trials than a full-factorial design³⁶. The mini-PV-modules electrical output (current-voltage characteristics), surface soil accumulation, and optical transmittance were measured in each case. The obtained data were analyzed statistically using Minitab^® version 21.4 (Minitab LLC, State College, PA, USA, https://www.minitab.com). The parameters used in the experimental design are presented in the following sections.
The performance of surface-modified glass samples and laminated test panels was evaluated in a laboratory-scale test chamber with controlled temperature, humidity, and airflow. The dimensions of the chamber were 100 cm × 100 cm × 100 cm. The experimental setup is illustrated in Fig. 2a. For the electrical performance testing of the laminated PV mini modules, the platform was tilted at an angle of 32.08°, which corresponds to the optimal inclination angle recommended for Konya based on regional solar irradiance studies³⁷. The quantity of soil accumulated on the surface was determined by measuring the weight difference before and after the experiments. The soil (dust) samples used in the experiments were collected from the vicinity of the small-scale solar power plant at Konya Technical University Technical Sciences Vocational School, where the outdoor tests were conducted. The samples were then saved to obtain particles smaller than 200 microns for use in the experiments. A 1000 W halogen light source was used to simulate sunlight during the laboratory testing of the laminated Mini-PV modules. To ensure compliance with AM1.5G irradiance standards, a calibrated pyranometer with a sensitivity of 7.99 mV/(kW/m²) was employed. The distance between the halogen lamp and the PV module was adjusted to obtain an irradiance level of 1000 W/m² on the module surface, and the light source was verified accordingly. The current and voltage outputs of the mini-PV modules were recorded over time under varying environmental conditions, including temperature, humidity, airflow rate, and dust concentration. This test chamber facilitated the precise evaluation of mini-PV modules performance under controlled conditions that are difficult to regulate in real-world environments, such as irradiance, soil (dust) load, temperature, and humidity. The data obtained from this setup serves as a baseline for modeling the real-world performance of the developed surface coatings. A schematic diagram of the experimental setup and a view of the constructed test system are presented in Figs. 2a, b, respectively.
(a) Schematic representation of the indoor dust deposition simulator used for controlled laboratory testing. (b) Photograph of the laboratory-scale experimental setup. (c) Block diagram of the monitoring system, including computer interface, TM4C1294 microcontroller, temperature, voltage, and current sensors, and tested PV modules. (d) 3D model illustrating the outdoor PV panel mounting structure equipped with a temperature sensor. (e) Actual photograph of the outdoor dust-accumulation experiment conducted on the coated and uncoated Mini-PV modules.
Based on the findings from laboratory-scale experiments, additional testing was carried out under real-world environmental conditions. In this context, the laminated mini-PV modules were installed at the small-scale solar power plant located within the campus of Konya Technical University Vocational School of Technical Sciences, as shown in Figs. 2(d) and 2(e). As illustrated in Fig. 2(c), the current, voltage, and temperature of the mini-PV modules were measured using sensors and recorded via a data acquisition system built around the TM4C1294 microcontroller. A custom interface program was developed to facilitate communication between the microcontroller and a computer via Ethernet, enabling real-time data collection. Measurements were acquired and logged at one-minute intervals using this user interface. The custom-designed system and the integrated data acquisition setup enabled accurate monitoring of the electrical output of each panel, providing a reliable basis for comparing the real-world performance of mini-PV modules with appropriate surface coatings. The experimental setup employed in this study was designed to simulate summer dust-loading conditions. Winter-specific environmental parameters such as low temperatures, increased humidity, and snow deposition could not be reproduced within the available laboratory infrastructure.
To determine the optimal coating conditions, glass lamellae were coated with an aluminum oxide (Al₂O₃) sol solution using spray pyrolysis at 250 °C for 20, 40, and 80 s. The glass lamellae were cleaned in succession with pure water, ethanol, acetone, and hexane, and then dried with an air gun prior to spray pyrolysis. Following deposition, the samples were cured at 500 °C to promote film formation. Surface analysis was performed using SEM, AFM, XRD, profilometry, and contact angle measurement. XRD patterns, SEM, and AFM images of the sample coated with Al₂O₃ sol for 20, 40, and 80 s are seen in Fig. 3. The sample coated for 20 s had a rough surface, as several large pores were visible in the SEM and AFM images (Fig. 3a1, a2). The corresponding XRD pattern (Fig. 3a3) lacked sharp peaks, indicating the amorphous nature of the coating. SEM and AFM micrographs of the 40-second deposition (Fig. 3b1, b2) revealed regularly spaced, droplet-shaped aggregations with a diameter of 186–434 nm. ImageJ measurements provided an average diameter of 284.3 ± 63.8 nm. No significant change in elevation was detected in the AFM scans, which presented a relatively flat surface. XRD data again confirmed the amorphous nature of the thin film (Fig. 3b3). The 80-second coated sample exhibited clearly defined signs of delamination in specific locations (Fig. 3c1, c2). SEM images indicated excessive Al₂O₃ deposition, which may have been responsible for the poor adhesion and peeling observed following thermal treatment. The coating thickness was estimated to be 1.238 ± 0.385 μm. AFM images also showed non-uniform height distribution. As with previous samples, the XRD pattern (Fig. 3c3) showed no crystallinity, confirming the amorphous structure. Profilometry analysis (using a Nanomap profilometer) quantified the coating thickness as 27 nm, 231 nm, and 1159 nm for 20,40, and 80 s sprayed samples, respectively. These results indicate that coating thickness increases with spray time, though not linearly, but rather in an exponential manner.
AFM (a1–c1), SEM (a2–c2), and XRD (a3–c3) results of Al₂O₃-sol-coated samples at coating durations of 20 s (a), 40 s (b), and 80 s (c).
To enhance surface hydrophobicity, the coated lamellae were functionalized with an oleic acid/n-hexane solution at 50 °C for 1 h. For clarity and brevity, sample names are abbreviated as CLx_OAy, where CL stands for “coated lamellae,” x is the coating duration in seconds, and y is the oleic acid concentration in percent (w/w) in hexane. For instance, CL40_OA1.5 refers to a lamella coated with Alumina sol for 40 s and treated with 1.5% oleic acid. In the functionalization process, three defined oleic acid concentrations (0.5%, 1.5%, and 4.5% w/w) were applied to the coated lamellae to evaluate the effect of surface modification level. For comparison, CL20_OA1.5 and CL80_OA1.5 samples were also prepared. Figure 4 presents the results of both AFM and SEM analyses of coated lamellae samples treated with varying concentrations of oleic acid (0.5%, 1.5%, and 4.5% w/w) and coating durations (20, 40, and 80s). Spherical aggregations were clearly observed in CL40_OA0.5 and CL40_OA1.5, whereas no such structures appeared in CL40_OA4.5, likely due to reduced aggregation under more acidic conditions. Aggregate diameters in CL40_OA0.5 ranged from 469 nm to 1.09 μm, while the average diameter in CL40_OA1.5 was 290 ± 116 nm. Both CL20_OA1.5 and CL80_OA1.5 also exhibited aggregation), with a lower degree in the CL20_OA1.5 sample. It is noteworthy that CL40_OA0.5 and CL40_OA1.5 exhibited significant spherical aggregations. CL40_OA0.5 demonstrated larger and more scattered clusters, while CL40_OA1.5 exhibited smaller, more uniform structures. These observations suggest that moderate oleic acid concentrations (1.5%) facilitate controlled self-assembly, whereas lower concentrations promote larger aggregate formation. Conversely, CL40_OA4.5 exhibited a smooth and homogenous surface devoid of visible aggregates, suggesting that the presence of excessive oleic acid may impede clustering, potentially due to surface saturation or heightened acidity. Samples with different coating durations, designated CL20_OA1.5 and CL80_OA1.5, also exhibited notable differences: CL20_OA1.5 exhibited irregular, rough topography and a paucity of aggregates, likely due to insufficient material deposition, whereas CL80_OA1.5 exhibited limited aggregation and flatter surfaces, possibly resulting from denser surface coverage that restricted oleic acid interaction. These results emphasize the combined effects of oleic acid concentration and coating time on surface morphology and aggregate formation.
AFM 3D surface topographies (a1–e1) and SEM micrographs (a2–e2) of oleic acid–functionalized Al₂O₃-sol-coated lamellae prepared under different coating durations and oleic acid concentrations. Panels (a1, a2), (b1, b2), and (c1, c2) correspond to CL40_OA0.5, CL40_OA1.5, and CL40_OA4.5, respectively, while panels (d1, d2) and (e1, e2) represent CL20_OA1.5 and CL80_OA1.5.
The primary aim of this study was to develop surface-modified Al₂O₃-based lamellae capable of reducing dust adhesion, thereby contributing to anti-soiling performance on PV surfaces. In this context, wettability characteristics provide an indirect but highly informative indicator of surface behavior, as they are closely related to adhesion energy, particle surface interactions, and the ease with which dust particles can be removed. The quantitative contact angle data presented in Table 1, together with the sessile-drop images in Supplementary Figure S1–S4, therefore offer valuable insights into how coating duration and oleic acid functionalization modulate the surface characteristics relevant to dust mitigation. The uncoated glass substrate exhibited a baseline contact angle of 38.04°, indicating a high surface energy that typically favors strong particle adhesion. Following the deposition of the Al₂O₃ sol–gel layer, the contact angle increased to 37.60° at 20 s, 55.43° at 40 s, and 55.98° at 80 s, showing that the evolving morphology of the oxide layer alters the wetting properties and potentially reduces dust–surface adhesion. Although these values remain within the wettable regime (< 90°), the increase suggests a reduction in surface energy that may contribute to lowering dust accumulation. Oleic acid functionalization further modified the surface behavior, producing systematic increases in contact angles across all samples. For the CL40 series, the measured angles were 63.79° (0.5%), 72.75° (1.5%), and 75.47° (4.5%), demonstrating that higher concentrations of the fatty acid enhance the organic surface coverage and influence surface particle interactions. Likewise, the samples functionalized at 1.5% oleic acid after 20 s and 80 s of coating produced contact angles of 66.12° and 79.59°, respectively. While none of these values exceed the hydrophobic threshold of 90°, the consistent upward trend confirms that both coating duration and oleic acid concentration contribute to modifying the surface in ways that are relevant for anti-soiling applications. It is important to emphasize that anti-soiling performance does not require hydrophobic or superhydrophobic behavior; instead, reduced surface energy, modified chemical functionality, and changes in micro/nanoscale morphology can meaningfully influence dust adherence and removal dynamics. The low standard deviations observed for all samples indicate that the functionalization process yields reproducible surface characteristics, further supporting its applicability in surface engineering for PV systems. Overall, the observed modifications in wettability though remaining below the hydrophobic regime demonstrate that the combination of Al₂O₃ sol–gel deposition and oleic acid functionalization effectively tunes the surface energy and interfacial behavior of the lamellae. These tunable characteristics are highly relevant for reducing dust adhesion and improving the anti-soiling potential of PV surfaces in real-world conditions.
UV-Vis transmission spectra of uncoated glass slides and Al₂O₃ sol-coated samples (CL20, CL40, CL80), including the sample functionalized with 1.5 wt% oleic acid (CL40_OA1.5), are seen in Fig. 5. The results demonstrate that optical transmission in the visible range (400–800 nm) improves with increasing coating duration. The CL20 sample exhibited the highest transmittance (> 80%). However, a slight reduction in transmittance was observed at longer coating durations and following oleic acid (OA) functionalization. Functionalization with OA appears to introduce additional absorption or scattering, reducing optical clarity compared to non-functionalized CL40.
UV spectra of lamellae treated with Al₂O₃ sol for 20 s, 40 s, and 80 s and a sample treated with Al₂O₃ sol for 40 s after functionalization with a solution containing 1.5% oleic acid by mass.
Based on the characterization results, the sample coated with Al₂O₃ sol for 40 s and subsequently functionalized with a 1.5 wt% oleic acid solution was identified as the most suitable. This configuration was selected as the key parameter for the development of test panels used in both laboratory-scale and outdoor environment experiments.
The amount of soil (dust) that accumulates on the surface of PV panels varies depending on environmental conditions. The rate at which soil (dust) is deposited depends on various factors, such as particle size, temperature, relative humidity, ambient soil (dust) concentration and wind speed. Geographical location, proximity to industrial areas and distance from the sea also significantly affect soil (dust) deposition levels in solar power plants. In this study, key parameters (temperature, humidity, ambient soil (dust) concentration and wind speed) were varied under controlled laboratory conditions to assess their effects. Untreated glass samples were compared with test panels that had been coated for 40 s using a functional solution containing 1.5 wt% oleic acid. A CCD was employed to plan a four-factor, three-level experimental design. The results of these experiments were analyzed using response surface methodology (RSM). The experimental parameters are given in Table 2. In the test setup detailed in previous sections, target conditions for temperature, humidity, and wind speed were first established and stabilized. Once equilibrium was reached, a certain amount of soil (dust) was introduced into the system. The installation was then maintained under these conditions for one hour. At the conclusion of this period, the quantity of soil (dust) deposited on the untreated glass and the functionally coated panels were quantified. In all experiments, consistently lower levels of soil (dust) accumulation were observed on functionally coated panels. Therefore, instead of data obtained for untreated and treated glass separately, the differences in soil (dust) accumulation were considered.
RSM is a set of mathematical and statistical techniques that are useful for modelling and analyzing the influence of various independent variables on a dependent variable. In this study, RSM was employed to investigate the impact of environmental factors on the difference in dust deposition between coated and functionalized samples and untreated glass in a controlled laboratory environment. In RSM, quadratic models are commonly used because they capture not only linear relationships between the variables and the response but also account for curvature and interaction effects. This provides a more accurate and flexible representation of complex systems. Equation (1) shows the model equations that represent the interactions of the variables.
where Y is response variable (e.g., soil (dust) accumulation), βo, β_i, β_ii and β_ij are intercept term, coefficients for linear effects, coefficients for quadratic (squared) effects and coefficients for interaction effects between variables, respectively. Also, X_i, X_j are independent variables, ε is random error term and k is number of factors in the model. The data collected were analyzed using Minitab version 22.3 and the following regression model was derived according to quadratic models:
where: a = temperature (°C); b = relative humidity (%); c = initial soil (dust) load (g); d = wind speed (km/h).
The regression model explains a high proportion of the variability in soil (dust) deposition differences on glass and treated glass, with an R² value of 91.40%. An adjusted R-square value of 83.87% indicated that the predictors included contribute significantly. Furthermore, a predicted R-squared value of 64.69% confirmed that the model has good predictive ability without overfitting. Analysis of variance (ANOVA) results are shown in Table 3. ANOVA results showed that the overall model is statistically significant (p = 0.000007). The linear terms for temperature (p = 0.000081), initial soil (dust) load (p = 0.000003) and wind speed (P = 0.000001) make a significant contribution to the model. However, relative humidity does not demonstrate significant individual effects, and none of the square terms are significant (p > 0.9). Also, only initial soil (dust) load (g)*wind speed (km/h) has significant individual effects on response in 2-way interaction terms.
Figure 6 presents six contour plots illustrating the interactive effects of diverse environmental factors, including temperature, relative humidity, initial soil (dust) load, and wind speed, on the ” soil (dust) Accumulation Difference.” Each plot is intended to illustrate the relationship between two independent variables, whilst ensuring that all other factors remain constant. This approach is intended to provide significant information regarding their combined effects on the effectiveness of the treatment in relation to soil (dust) accumulation. The color gradients in each plot are indicative of the magnitude of the soil (dust) accumulation difference; lighter shades indicate a lower difference, and darker shades indicate a higher difference.
Interaction contour plots of the effects of environmental parameters on the soil accumulation difference: temperature and relative humidity (a), temperature and initial soil (dust) load (b), temperature and wind speed (c), relative humidity and initial soil (dust) load (d), relative humidity and wind speed (e), and initial soil (dust) load and wind speed (f).
The response variable in this analysis is the difference in soil (dust) accumulation obtained by subtracting the amount of soil (dust) retained on an uncoated (unmodified) surface from the amount retained on a surface modified with wettability-tuned Al₂O₃-based coatings. This difference is an indicator of the antifouling effectiveness of the coating under changing environmental conditions. Figure 6a shows the interaction between temperature, relative humidity, and the response variable. Under constant initial soil (dust) load (2.75 g) and wind speed (17.5 km/h), the soil (dust) accumulation difference decreases as temperature increases. The effect of relative humidity is relatively limited, but a slight increase in soil (dust) accumulation difference is observed with increasing humidity. This trend can be attributed to the decreased soil (dust) adhesion at higher temperatures due to drier surface conditions, which may increase the self-cleaning effect of the coating. Figure 6b shows the interaction between temperature, initial soil (dust) load, and soil (dust) accumulation difference. With constant relative humidity and wind speed, the soil accumulation difference decreases significantly with increasing temperature, while it increases with higher initial soil (dust) load. The highest soil (dust) accumulation difference occurs at low temperature and high soil (dust) load, indicating that the coating is particularly effective under intense soil (dust) exposure when the temperature is low. Figure 6c investigates the interaction between temperature, wind speed, and soil (dust) accumulation difference. At constant relative humidity and initial soil (dust) load, both increasing temperature and wind speed contribute to the reduction in soil (dust) accumulation difference. The effect of wind speed is particularly pronounced because lower wind speeds result in higher soil (dust) accumulation differences. This indicates that the contribution of the coating to soil (dust) reduction becomes more critical when there is insufficient airflow. Figure 6d shows the interaction between relative humidity, initial soil (dust) load, and soil (dust) accumulation difference. While temperature and wind speed are kept constant, an increase in initial soil (dust) load led to a significant increase in soil (dust) accumulation difference. In this case, the effect of relative humidity is relatively limited. These results indicate that the effectiveness of the coating becomes more pronounced under higher soil (dust) load conditions. Figure 6e shows the combined effects of relative humidity and wind speed. With constant temperature and soil (dust) load, the soil (dust) deposition difference decreases with increasing wind speed, while relative humidity has a relatively small effect. This finding reinforces the importance of wind in helping to remove soil (dust) from both surfaces, although the coating helps to a limited extent in maintaining lower deposition under calm conditions. Finally, Fig. 6f examines the interaction between the initial soil (dust) load and wind speed. As expected, the soil (dust) deposition difference increases with higher soil (dust) load and decreases with increasing wind speed. The maximum difference is observed under conditions of low wind speed and high soil (dust) load, clearly showing the opposing effects of these two parameters. This indicates that under harsh environmental conditions such as low wind speeds and high soil (dust) loads the application of a wettability-tuned coating surface treatment significantly mitigates soil (dust) deposition. When all effects are considered, the parameters where coating effectiveness stand out are high initial soil (dust) load and low wind speed. Conversely, higher wind speed and higher temperature reduce this difference, probably due to the natural cleaning effects acting on both surfaces. Relative humidity shows a less pronounced effect compared to the other factors. Overall, these findings provide valuable insights into how surface coating performance varies under different environmental conditions and highlight the potential to reduce soil (dust) accumulation on solar panels.
In this study, two types of Mini-PV modules were prepared: the Reference Panel, incorporating standard glass without any surface treatment, and the Sample Panel, featuring glass coated with aluminum oxide (Al₂O₃) and functionalized with oleic acid. Both panels were positioned within a specialized experimental setup that enabled precise control of environmental parameters, including temperature, relative humidity, initial soil (dust) concentration, and wind speed.
Prior to the initiation of each experiment, the system was allowed to reach thermal and environmental equilibrium. At the start of the experiment (t = 0 min), the power output of both the reference and sample panels was precisely measured and recorded by acquiring voltage and current data. To account for temporal variations in instantaneous power (calculated as Current × Voltage), the total energy produced over a fixed interval (1 min) was determined by integrating the area under the power–time curve. Following this initial measurement, a predetermined amount of soil (dust) defined by the experimental design was uniformly applied to the panel surfaces under equilibrium conditions. The system was then held under these conditions for a duration of 1 h (60 min). At the end of this period, the power output of both panels was re-measured using the same procedure. The percentage loss in power generation efficiency for each panel was subsequently calculated based on the initial and final measurements, using Eq. (3).
where E _initial represents the total energy produced at the beginning, and E _final represents the total energy produced after 1 h. Unlike the previous section, where treated and untreated glass surfaces were evaluated separately, a four-factor, three-level RSM was employed in this section. The response variable was defined as the difference in percentage efficiency loss between the untreated and surface-functionalized panels. The results obtained are summarized in Table 2. To investigate the influence of environmental parameters on this response, a quadratic polynomial regression model was developed using the Minitab statistical analysis software. The independent variables included temperature (°C), relative humidity (%), initial soil (dust) load (g) and wind speed (km/s). To simplify the model presentation, these variables were coded as follows: temperature = a, relative humidity = b, soil (dust) load = c and wind speed = d. The resulting regression model is expressed as follows:
The model yielded a coefficient of determination (R²) of 0.837, indicating that approximately 83.7% of the variation in the difference in efficiency loss between panels was explained by the fitted regression model. However, the adjusted R² value was significantly lower at 0.694, indicating that although the model fits the available data well, some terms may not contribute significantly to the explanatory power of the model after accounting for the number of terms included. Moreover, the predicted R² was markedly lower at 25.1%, indicating potential limitations in the model’s ability to generalize to new data. This discrepancy may be attributed to factors such as multicollinearity, overfitting, or insufficient representation of the experimental space.
The results of ANOVA, summarized in Table 4, provide important data with which to evaluate the statistical significance of the model components. The obtained regression model was found to be statistically significant (F = 5.86, p = 0.00059), confirming that the independent variables have a significant collective effect on the difference in efficiency loss. This indicates that the effectiveness of the coating varies under different environmental conditions. Among the linear terms, initial soil (dust) load (p = 0.03234) and wind speed (p = 0.02366) were statistically significant. Among the square terms, (temperature)², relative (humidity)² and (wind speed)² was significant, indicating nonlinear effects. Several interaction terms exhibited highly significant effects, particularly temperature × wind speed (p = 0.00167) and relative humidity × soil (dust) load (p = 0.00083). The lack of fit test was insignificant (p = 0.62921), indicating a good fit between the model and the experimental data.
Interaction contour plots of the effects of environmental parameters on the Efficiency loss difference: temperature and relative humidity (a), temperature and initial soil (dust) load (b), temperature and wind speed (c), relative humidity and initial soil (dust) load (d), relative humidity and wind speed (e), and initial soil (dust) load and wind speed (f).
This study investigates the differential efficiency loss in Mini-PV modules fabricated with untreated glass versus those incorporating surface-functionalized glass (Al₂O₃-coated and oleic acid-functionalized), based on energy measurements collected over a one-hour period. The percentage efficiency loss was calculated using the initial and final energy output values for each panel type, and the difference between them served as an indicator of the effectiveness of the surface modification. Response surface contour plots were employed to visualize the influence of interactions among temperature, relative humidity, initial soil (dust) load, and wind speed on this efficiency loss difference (Fig. 7a–f). Figure 7a illustrates that the greatest performance enhancement resulting from surface functionalization occurs under two distinct environmental conditions: at moderate relative humidity (~ 60%) combined with high temperatures (> 35 °C), and at low temperatures (~ 25 °C) with elevated humidity levels (> 57%). This behavior is attributed to the functionalized panels’ superior ability to maintain optical clarity under such conditions, thereby resulting in a more pronounced efficiency difference compared to untreated panels. Similarly, Fig. 7b shows that the efficiency loss difference increases as the initial soil (dust) load increases above 1.5 g, especially at high temperatures. This may mean that the surface treatments are particularly effective in conditions of heavy fouling and prevent soil (dust) from adhering strongly to the panel. The reducing effect of wind speed on the efficiency loss differences is clearly reflected in Fig. 7c and f. Figure 7c shows that at high temperatures and low wind speeds, functionalized panels provide an efficiency advantage over untreated panels. However, when the wind speed increases above 15 km/h, this advantage decreases, probably because the wind helps soil (dust) removal on both types of surfaces. Figure 7d highlights that the combination of high humidity and high soil (dust) load results in the highest difference in efficiency loss, with humidity worsening the fouling on untreated panels, while functional coatings resist such effects. In Fig. 7e, increasing wind speed in humid conditions narrows the performance gap again, showing that airflow effectively reduces moisture-related sticking. Finally, the influence of wind speed and initial dust load under stagnant and dust-prone environmental conditions was demonstrated in Fig. 7f. The contour distribution indicated that the efficiency-loss difference was maximized when the dust load was high and the wind speed was low, showing that limited airflow allowed greater retention and accumulation of dust on the panel surface. As wind speed increased, a gradual reduction in the efficiency-loss difference was observed, which was attributed to the partial removal or redistribution of loosely attached particles. Overall, these trends indicated that measurable resistance to dust-induced performance degradation was provided by the functionalized glass surfaces, resulting in enhanced stability and reduced efficiency loss under hot, humid, and dust-rich environmental conditions.
In this section, it is aimed to assess the real-world operational performance of PV mini-modules equipped with the functionalized coatings, thereby determining the practical relevance and field effectiveness of the proposed anti-soiling surface.
A total of six laminated PV mini modules were employed in the outdoor experiments conducted under real-world conditions. Four of these mini-modules (PV1, PV2, PV3, and PV4) were laminated with functionalized glass surfaces, whereas the remaining two (PV5 and PV6) were laminated with standard uncoated glass. However, no reliable data were obtained from PV4 due to an electrical connection failure that occurred during the lamination and installation stage. The malfunction resulted in intermittent current transmission and ultimately prevented stable measurements, indicating that the PV cell was likely damaged or electrically disconnected. Consequently, PV4 was excluded from all graphical evaluations and statistical analyses.
Data collection was performed between July 15 and August 12, with measurements recorded daily between 07:00 and 18:00. During this period, current, voltage, and panel temperature were monitored at 20-second intervals. Each mini PV module consisted of a single 8 × 16 cm PV cell laminated with a 10 × 18 cm glass cover prepared with either functionalized or unfunctionalized surfaces. The experimentally measured operating parameters of the laminated PV mini modules are summarized in Table 5.
Tempered glass differs from regular (annealed) glass in its significantly higher mechanical strength, impact resistance, and thermal shock tolerance, which are achieved through controlled heat-treatment processes. Tempered glass also exhibits a characteristic residual compressive stress on its surface, which is introduced during the rapid quenching stage of heat treatment. This compressive stress layer not only increases fracture resistance but also ensures that, in the event of breakage, the glass fragments into small granular pieces rather than sharp shards, providing enhanced safety and durability under outdoor environmental loads. Although both glasses exhibit similar optical transmittance, their mechanical and thermal properties can influence coating adhesion, durability, and surface stress distribution. For this reason, both tempered and regular glass substrates were included in the preparation of the laminated PV mini-modules to evaluate whether the functionalized surfaces provide consistent anti-soiling performance across different glass types.
For performance evaluation, four representative days were randomly selected: July 17, July 21, July 30, and August 6. On these dates, the power outputs of the coated and uncoated Mini-PV modules were compared. Hourly average power values and total daily energy production were calculated and are graphically presented in Fig. 8. The corresponding numerical results are summarized in Table 6.
Average power output of coated (PV1, PV2, PV3) and uncoated (PV5, PV6) Mini-PV modules. The values represent hourly-averaged power measurements recorded during the outdoor tests. Hourly average power on July 17 (a), July 21 (b), July 30 (c), and August 6 (d).
According to the results, the coated mini-PV modules generated higher power output on July 17 and 21. On July 30, no significant performance difference was observed between the coated and uncoated mini-PV modules. Conversely, on August 6, the uncoated modules exhibited higher power output. This behaviour can be attributed to several environmental factors that are known to influence outdoor PV system performance. Several environmental and operational mechanisms are known to amplify power losses in PV modules under real-world outdoor exposure. First, dust accumulation not only obstructs incoming irradiance but also increases the operating temperature of PV modules by forming a thermally insulating layer. This dual mechanism has been experimentally shown to reduce PV output at increasing dust mass, particularly under high ambient temperatures. Second, high relative humidity promotes the cementation of dust particles, forming hardened or mud-like deposits that persist on the glass surface and cause more severe optical attenuation than dry dust alone³⁸. Third, long-term exposure to wind-driven particulates gradually abrades the glass surface; this abrasion increases surface roughness and decreases optical transmittance, resulting in irreversible efficiency degradation³⁹. Furthermore, non-uniform dust deposition can induce electrical mismatch and partial shading losses, which lead to highly non-linear reductions in power output. As summarized in the mismatch-loss literature, localized shading or soiling may produce disproportionately large power losses even when only a small portion of the surface is affected⁴⁰. Collectively, these factors indicate that the observed variations in power output during outdoor testing arise from the combined effects of soiling behavior, humidity-driven cementation, thermal impacts, surface abrasion, and mismatch phenomena rather than dust deposition alone.
Figure 9 presents the daily total power output of the mini-PV modules alongside the corresponding daily total solar irradiation measured between July 15 and August 12. Examination of the graph reveals a noticeable decline in the power output of the coated PV1, PV2, and PV3 mini-PV modules starting in early August, whereas the power output of the uncoated PV5 and PV6 mini-PV modules remained relatively stable throughout the same period.
Total power generated between July 15 and August 12.
This performance degradation is attributed to the interaction between elevated ambient temperatures and the oleic acid-based hydrophobic coating. It is hypothesized that airborne dust and organic particulates accumulated on the functionalized surface, increasing contamination, reducing light transmittance, and thereby negatively impacting overall energy efficiency.
To verify this hypothesis, the experimental setup was cleaned with water, and follow-up measurements were conducted on August 18, 2023. As shown in Fig. 10b, the hourly average current values indicate that, post-cleaning, the coated mini-PV modules produced higher current outputs than the uncoated ones. This confirms that surface contamination had a substantial adverse effect on the performance of coated mini-PV modules. Additionally, Fig. 10a, which presents current data recorded on July 17 under initially clean conditions, further supports this conclusion, demonstrating that the coated PV mini-PV modules initially outperformed the uncoated counterparts.
Hourly average current values. Average current on July 17 (mA) (a), average current on August 18 (mA) (b).
This study compared the performance of mini-PV modules with coated and uncoated glass surfaces under real outdoor conditions. Coated mini-PV modules generally produce higher power and current outputs, especially when they were clean. However, from early August, the performance of coated cells declined, likely due to environmental factors such as high temperatures, airborne dust, and organic particulates interacting with the coating. After cleaning, the coated cells regained their superior performance, highlighting the importance of surface cleanliness for maintaining efficiency. These results underscore the need to consider both environmental sensitivity and maintenance requirements when evaluating surface coating technologies for photovoltaic systems.
The comparative findings presented in Table 7 demonstrate clear differences among anti-soiling (AS) and surface-modified coating technologies in terms of wettability control, optical behaviour, environmental durability, and their resulting impact on outdoor PV performance. The hybrid Al₂O₃–oleic acid (OA) coating developed in this study exhibits a balanced performance profile, characterized by enhanced surface wettability rather than strong hydrophobicity combined with low optical loss and measurable outdoor power improvement. As shown in Table 1, the Al₂O₃–OA coating provides a moderate contact angle (~ 75°), effectively lowers dust accumulation in indoor soiling-chamber tests, and maintains optical transmittance above 80%, leading to a stable and reproducible outdoor power gain. This wettability-enhanced behavior distinguishes it from superhydrophobic fluoropolymer coatings, which achieve WCA values exceeding 150° but degrade rapidly under abrasion, UV exposure, and repeated environmental cycles. Table 7 additionally shows that PDMS/TiO₂–SnO₂ nano-ceramic coatings deliver strong short-term benefits, reporting efficiency gains above 5%, largely due to photocatalytic self-cleaning. Nevertheless, their long-term durability under combined stressors such as humidity, UV radiation, and abrasive forces remains uncertain. Likewise, commercial hydrophobic AS coatings demonstrate significant cleaning gains during wind and rain events but quickly lose performance in humid regions, where their water-repellent properties diminish. In contrast, silica-based AR/AS coatings maintain excellent long-term optical stability throughout multi-year outdoor testing, although their limited wettability control results in only moderate anti-soiling behavior. Chemically etched micro/nano-textured glass, based purely on morphological modification rather than surface chemistry, exhibits reduced dust adhesion and stable performance; however, the absence of controlled wettability limits their self-cleaning potential.
This study presents a novel approach for enhancing photovoltaic (PV) panel performance by employing oleic acid-functionalized Al₂O₃ nanoparticle coatings as a passive anti- soil (dust) strategy. Unlike conventional methods, the study explores multiple coating conditions by varying both the application duration (20, 40, and 80 s) and oleic acid concentration (0.5%, 1.5%, and 4.5%). The optimal combination was identified as a 40-second spray duration with a 1.5% oleic acid solution. Laboratory experiments demonstrated that the coated surfaces accumulated, on average, 6.9 mg/cm² less dust compared to uncoated surfaces, translating into a 0.6%–3.0% reduction in energy efficiency losses. Field tests conducted under real environmental conditions revealed that coated panels initially delivered higher daily energy output, producing 0.5–0.8 W more power per day than their uncoated counterparts during certain periods.
However, a decline in performance was observed in the coated panels starting in early August, attributed to environmental stressors such as elevated temperatures (> 35 °C), low wind speeds (< 10 km/h), and the presence of airborne hydrophobic pollutants (e.g., vehicle exhaust, industrial emissions, and agricultural particles). These contaminants adhered to the hydrophobic surface, impairing optical transmittance and reducing power output. Notably, cleaning the panel surfaces restored their performance, confirming the reversible nature of the degradation caused by surface contamination.
In conclusion, oleic acid-modified Al₂O₃ coatings show potential as a passive anti-soiling solution, especially in arid and dust-prone regions with limited water resources. However, their long-term effectiveness is affected by both particulate dust and hydrophobic atmospheric pollutants. Thus, while these coatings are promising, sustainable and consistent performance will require periodic cleaning, enhanced coating durability, and the development of alternative or hybrid protective strategies.
In future studies, the performance of the proposed coating technique will be benchmarked against established nanoparticle-based coatings, including lotus-leaf-inspired hierarchical textured surfaces, grain-structured coatings, and systems modified with suitable surface-active agents, in order to more comprehensively evaluate its comparative advantages and potential application areas. It should be noted that this study was conducted under conditions representative of summer dust-loading, and winter-related environmental factors, including reduced temperatures, elevated humidity, and snow accumulation, were not assessed due to laboratory limitations. Future studies incorporating multi-seasonal and multi-location evaluations would provide a more comprehensive understanding of the coating’s environmental robustness.
No datasets were generated or used in this study. All analyses were performed using experimentally obtained measurements.
The original online version of this Article was revised: In the original version of this Article the Funding section was omitted. The Funding section now reads: “The present study received financial assistance from the Scientific and Technological Research Council of Turkey (TUBITAK) under Grant No. 122E197. The authors express their gratitude to TUBITAK for financial support.”
Franjić, S. & Unleashing Sustainable Energy. The Sun, earth’s largest and most powerfu source. J. Sustainable Dev. 4 (2), 1–9. https://doi.org/10.56388/susd230615 (2023).
Article  Google Scholar 
Özbeyaz, A. Estimating solar power generation with RF, GB, and SVR algorithms based on meteorological data and orientation angles: Adıyaman case study, Electrical Eng. Energy, 4, 2, 1–14, (2025). https://doi.org/10.64470/elene.2025.1006
Yorulmaz, M. & Taş, T. İ. Carbon footprint reduction and strategic benefits of energy efficiency: a case study in the healthcare sector. Electrical Eng. Energy, (2025). https://doi.org/10.64470/0.2025.11
B. S. Gumus. Türkiye surpasses 2025 solar target as capacity doubles in 2.5 years. https://ember-energy.org/app/uploads/2025/01/EN-Report_-Turkiye-surpasses-2025-solar-target-as-capacity-doubled.pdf (accessed: Semptember 10, 2025).
Lopez-Lorente, J. et al. Characterizing soiling losses for photovoltaic systems in dry climates: a case study in cyprus. Sol. Energy. 255, 243–256. https://doi.org/10.1016/j.solener.2023.03.034 (2023).
Article  ADS  Google Scholar 
Zaihidee, F. M., Mekhilef, S., Seyedmahmoudian, M. & Horan, B. Dust as an unalterable deteriorative factor affecting PV panel’s efficiency: why and how. Renew. Sustain. Energy Rev. 65, 1267–1278. https://doi.org/10.1016/j.rser.2016.06.068 (2016).
Article  Google Scholar 
Fouad, M., Shihata, L. A. & Morgan, E. I. An integrated review of factors influencing the perfomance of photovoltaic panels. Renew. Sustain. Energy Rev. 80, 1499–1511. https://doi.org/10.1016/j.rser.2017.05.141 (2017).
Article  Google Scholar 
Kayri, I. & Bayar, M. T. Investigation of dust effect on the efficiency of photovoltaic panels: the case of Batman, In: International Symposium on Engineering, Natural and Social Sciences ISENS-21, 88–96. (2021).
Cordero, R. et al. Effects of soiling on photovoltaic (PV) modules in the Atacama desert. Sci. Rep. 8 (1), 13943. https://doi.org/10.1038/s41598-018-32291-8 (2018).
Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 
Herrmann, W., Schweiger, M., Tamizhmani, G., Shisler, B. & Kamalaksha, C. Soiling and self-cleaning of PV modules under the weather conditions of two locations in Arizona and South-East India, In: 2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC) 1–5, (IEEE, 2015). https://doi.org/10.1109/PVSC.2015.7356131
Grammatico, M. A. & Littmann, B. W. Quantifying the anti-soiling benefits of anti-reflective coatings on first solar cadmium telluride PV modules, In: 2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), 1697–1701, (IEEE, 2016). https://doi.org/10.1109/PVSC.2016.7749913
Redekar, A., Dhiman, H. S., Deb, D. & Muyeen, S. On reliability enhancement of solar PV arrays using hybrid SVR for soiling forecasting based on WT and EMD decomposition methods. Ain Shams Eng. J. 15 (6), 102716. https://doi.org/10.1016/j.asej.2024.102716 (2024).
Article  Google Scholar 
Gostein, M. et al. Soiling measurement station to evaluate anti-soiling properties of PV module coatings, In: 2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), : 3129–3131, (IEEE, 2016). https://doi.org/10.1109/PVSC.2016.7750242
Borah, P., Micheli, L. & Sarmah, N. Analysis of soiling loss in photovoltaic modules: a review of the impact of atmospheric parameters, soil properties, and mitigation approaches, Sustainability, 15, 24, 16669, (2023). https://doi.org/10.3390/su152416669
Adekanbi, M. L., Alaba, E. S., John, T. J., Tundealao, T. D. & Banji, T. I. Soiling loss in solar systems: A review of its effect on solar energy efficiency and mitigation techniques. Clean. Energy Syst. 7, 100094. https://doi.org/10.1016/j.cles.2023.100094 (2024).
Article  Google Scholar 
Abderrezek, M. & Fathi, M. Experimental study of the dust effect on photovoltaic panels’ energy yield. Sol. Energy. 142, 308–320. https://doi.org/10.1016/j.solener.2016.12.040 (2017).
Article  ADS  Google Scholar 
Hossain, M. I., Ali, A., Bermudez Benito, V., Figgis, B. & Aïssa, B. Anti-soiling coatings for enhancement of PV panel performance in desert environment: a critical review and market overview, Materials, 15, 20,7139, (2022). https://doi.org/10.3390/ma15207139
Huang, Z. S. et al. Experimental investigation of the anti-soiling performances of different wettability of transparent coatings: Superhydrophilic, hydrophilic, hydrophobic and superhydrophobic coatings. Sol. Energy Mater. Sol. Cells. 225, 111053. https://doi.org/10.1016/j.solmat.2021.111053 (2021).
Article  CAS  Google Scholar 
Wang, W. et al. Compact nanopillar array with enhanced anti-accumulation of multiphase matter on transparent superhydrophobic glass. J. Mater. Chem. A. 11 (35), 18679–18688. https://doi.org/10.1039/D3TA03090C (2023).
Article  CAS  Google Scholar 
Abdrabo, M., Elkaseer, A., Elshazly, E., El-Deab, M. S. & El-Mahallawi, I. Experimental examination of enhanced nanoceramic-based self-cleaning sprays for high-efficiency hydrophobic photovoltaic panels, Coatings,14, 10, 1239, (2024). https://doi.org/10.3390/coatings14101239
Shahzad, N. et al. Impacts of soiling on solar panel performance and state-of-the-art effective cleaning methods: A recent review. J. Clean. Prod. 145119. https://doi.org/10.1016/j.jclepro.2025.145119 (2025).
Tayel, S. A., Abu El-Maaty, A. E., Mostafa, E. M. & Elsaadawi, Y. F. Enhance the performance of photovoltaic solar panels by a self-cleaning and hydrophobic nanocoating, Sci. Rep., 12, 1, 21236, (2022). https://doi.org/10.1038/s41598-022-25667-4
Shuhua, T., Qinwen, Z., Jing, Z. & Jie, F. Icephobic and antisoiling performance of PDMS coating filling with inert silicon oil after prolonged outdoor exposure. J. Coat. Technol. Res. 22 (2), 791–802. https://doi.org/10.1007/s11998-024-01009-z (2025).
Article  CAS  Google Scholar 
Abhinav, A., Banavath, R. & Mallick, S. Development of mechanically robust antisoiling coatings for photovoltaic module efficiency retention. ACS Appl. Eng. Mater. 1 (8), 2050–2061 (2023).
Article  CAS  Google Scholar 
Schmidt, H. Multifunctional inorganic-organic composite sol-gel coatings for glass surfaces. J. Non-cryst. Solids. 178, 302–312. https://doi.org/10.1016/0022-3093(94)90299-2 (1994).
Article  ADS  CAS  Google Scholar 
Chundi, N. et al. Quantum-sized TiO2 particles as highly stable super-hydrophilic and self-cleaning antisoiling coating for photovoltaic application. Sol. Energy. 258, 194–202. https://doi.org/10.1016/j.solener.2023.04.062 (2023).
Article  ADS  CAS  Google Scholar 
Zhu, C. et al. Antisoiling performance of Lotus leaf and other leaves after prolonged outdoor exposure. ACS Appl. Mater. Interfaces. 12, 53394–53402. https://doi.org/10.1021/acsami.0c13477 (2020).
Article  CAS  PubMed  Google Scholar 
Elsafi, A., Aïssa, B., Ilse, K. & Abdallah, A. Performance and durability of anti-soiling and anti-reflective coatings for photovoltaic systems in desert climates. Sol. Energy. 293 (11344, 6, ). https://doi.org/10.1016/j.solener.2025.113446 (2025).
Rehman, M. A. et al. Development of novel robust polymer-based functional coatings for enhanced self-cleaning and dust mitigation on glass surfaces: implications for photovoltaic efficiency optimization. Surf. Interfaces. 107197. https://doi.org/10.1016/j.surfin.2025.107197 (2025).
Chala, G. T., Sulaiman, S. A., Chen, X. & Al Shamsi, S. S. Effects of nanocoating on the performance of photovoltaic solar panels in Al Seeb, Oman, Energies,17, 12, 2871, (2024). https://doi.org/10.3390/en17122871
Aljdaeh, E. et al. Performance enhancement of self-cleaning hydrophobic nanocoated photovoltaic panels in a dusty environment, Energies, 14,. 20, 6800, (2021). https://doi.org/10.3390/en14206800
Tuo, H. et al. A comparative study of the effects of superhydrophobic and superhydrophilic coatings on dust deposition Mitigation for photovoltaic module surfaces, Coatings,15, 5, 614, (2025). https://doi.org/10.3390/coatings15050614
Guo, R. et al. Micron-smooth, robust hydrophobic coating for photovoltaic panel surfaces in arid and dusty areas, Coatings, 14, 2, 239, (2024). https://doi.org/10.3390/coatings14020239
Wang, J., Yang, S., Chen, M. & Xue, Q. Preparation and characterization of arachidic acid self-assembled monolayers on glass substrate coated with sol–gel Al2O3 thin film. Surf. Coat. Technol. 176 (2), 229–235. https://doi.org/10.1016/S0257-8972(03)00632-7 (2004).
Article  CAS  Google Scholar 
Soleimani, E. & Zamani, N. Surface modification of alumina nanoparticles: A dispersion study in organic media. Acta Chim. Slov. 64 (3), 644–653. https://doi.org/10.17344/acsi.2017.3459 (2017).
Article  CAS  PubMed  Google Scholar 
Ferreira, S. L. C. et al. Statistical designs and response surface techniques for the optimization of chromatographic systems. J. Chromatogr. A. 1158, 1–2. https://doi.org/10.1016/j.chroma.2007.03.051 (2007).
Article  CAS  Google Scholar 
Arslan, M. & Çunkaş, M. An experimental study on determination of optimal Tilt and orientation angles in photovoltaic systems. J. Eng. Res. 13 (3), 2689–2701. https://doi.org/10.1016/j.jer.2024.07.015 (2024).
Article  Google Scholar 
Sher, A. A., Ahmad, N., Sattar, M., Ghafoor, U. & Shah, U. H. Effect of various dusts and humidity on the performance of renewable energy modules, Energies 16,13, 4857, (2023). https://doi.org/10.3390/en16134857
Agea-Blanco, B., Meyer, C., Müller, R. & Günster, J. Sand erosion of solar glass: specific energy uptake, total transmittance, and module efficiency. Int. J. Energy Res. 42 (3), 1298–1307. https://doi.org/10.1002/er.3930 (2018).
Article  CAS  Google Scholar 
Dhass, A., Beemkumar, N., Harikrishnan, S. & Ali, H. M. A review on factors influencing the mismatch losses in solar photovoltaic system. Int. J. Photoenergy. 2022 (1), 2986004. https://doi.org/10.1155/2022/2986004 (2022).
Article  CAS  Google Scholar 
Nishioka, K., Moe, S. P. & Ota, Y. Long-term reliability evaluation of silica-based coating with antireflection effect for photovoltaic modules, Coatings, 9, 1, 49, (2019). https://doi.org/10.3390/coatings9010049
Ravi, P. M., Simpson, L. J., Choudhary & Mathew and and Darshan and Mantha, Shanmukha and Subramanian, Sai and Virkar, Shalaim and Curtis, Telia and Tamizhmani, Govindasamy, indoor soil deposition chamber: evaluating effectiveness of antisoiling coatings. IEEE J. Photovolt. 9, 227–232. https://doi.org/10.1109/JPHOTOV.2018.2877021 (2019).
Article  Google Scholar 
Bhaduri, A. A. S., Mallick, S., Shiradkar, N. S. & Kottantharayil, A. Identification of stressors leading to degradation of antisoiling coating in warm and humid climate zones. IEEE J. Photovolt. 10, 166–172. https://doi.org/10.1109/JPHOTOV.2019.2946709 (2020).
Article  Google Scholar 
Bhaduri, R. B. S., Farkade, M., Mallick, S., Shiradkar, N. & Kottantharayil, A. Nderstanding multiple stressors which degrade antisoiling coatings: combined effect of Rain, Abrasion, and UV radiation. IEEE J. Photovolt. 13, 603–609. https://doi.org/10.1109/JPHOTOV.2023.3273812 (2023).
Article  Google Scholar 
Tobosque, P., Núñez, J., Elgueda, A., Morán, L. & Carrasco, C. Modifying the surface roughness of solar glass: A passive mitigation method of soiling. Sustain. Energy Technol. Assess. 81, 104447. https://doi.org/10.1016/j.seta.2025.104447 (2025).
Article  Google Scholar 
Lange, K. et al. Abrasion testing of anti-reflective coatings under various conditions. Sol. Energy Mater. Sol. Cells. 240, 111732. https://doi.org/10.1016/j.solmat.2022.111732 (2022).
Article  CAS  Google Scholar 
Nayshevsky, I., Xu, Q., Barahman, G. & Lyons, A. Anti-reflective and anti-soiling properties of a KleanBoost™, a superhydrophobic nano-textured coating for solar glass, In: IEEE 44th Photovoltaic Specialist Conference (PVSC), 2285–2290,(IEEE, 2017)https://doi.org/10.1109/PVSC.2017.8366777
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The present study received financial assistance from the Scientific and Technological Research Council of Turkey (TUBITAK) under Grant No. 122E197. The authors express their gratitude to TUBITAK for financial support.
Vocational School of Technical Sciences, Department of Electricity and Energy Technologies, Konya Technical University, Konya, Türkiye
Mustafa Arslan
Vocational School of Technical Sciences, Department of Chemistry and Chemical Processing Technologies, Konya Technical University, Konya, Türkiye
İlyas Deveci
Vocational School of Technical Sciences, Department of Electronics and Automation Technologies, Konya Technical University, Konya, Türkiye
Cemile Arslan
Department of Electrical and Electronics Engineering, Selçuk University, Konya, Türkiye
Mehmet Çunkaş
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MA, CA, and ID performed the computational work, prepared figures and/or tables, and contributed to writing the main manuscript. MA and ID conceived and designed the experiments, performed the experiments, and analyzed the data. MÇ contributed to writing, reviewing, and editing the manuscript. All authors read and approved the final version of the manuscript.
Correspondence to Mehmet Çunkaş.
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Arslan, M., Deveci, İ., Arslan, C. et al. A new anti-soiling approach based on oleic acid-modified Al₂O₃ nanocoatings for photovoltaic panels. Sci Rep 16, 7615 (2026). https://doi.org/10.1038/s41598-026-38041-5
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Received: 30 September 2025
Accepted: 28 January 2026
Published: 06 February 2026
Version of record: 25 February 2026
DOI: https://doi.org/10.1038/s41598-026-38041-5
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