Evaluation of the adhesion forces between dust particles and photovoltaic module surfaces

Isaifan, Rima J.; Johnson, Daniel J.; Ackermann, Luis; Figgis, Benjamin; Ayoub, M.

doi:10.1016/j.solmat.2018.11.031

Cited by 118 publications

(52 citation statements)

References 43 publications

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“…High humidity causes water (including soluble particles) to condense between the insoluble particles and the surface. Capillary adhesion forces are most dominant at high humidity [25], which are caused by surface tension at the liquid-solid interface and the Laplace pressure (pressure between the atmosphere and liquid meniscus) [24]. When the liquid evaporates, particles compact together due to surface tension.…”

Section: Cementationmentioning

confidence: 99%

Testing the Durability of Anti-Soiling Coatings for Solar Cover Glass by Outdoor Exposure in Denmark

et al. 2020

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The presence of soiling on photovoltaic modules reduces light transmission through the front cover glass to the active absorber, thereby reducing efficiency and performance. Current soiling mitigation techniques are expensive and/or ineffective. However, anti-soiling coatings applied to the solar cover glass have the potential to reduce soiling for long periods of time without continuous maintenance. This paper reports the performance of two transparent hydrophobic coatings (A and B) exposed to the outdoor environment of coastal Denmark for 24 weeks. A comparison was made between the performance of coated and uncoated glass coupons, periodically cleaned coupons, and accelerated laboratory tests. Although initial results were promising, water contact angle and transmittance values were found to decline continuously for all coated and uncoated coupons. Surface blisters, film thickness reduction, changes in surface chemistry (fluorine loss), and abrasion damage following cleaning were observed. Coupons cleaned every 4 weeks showed a restoration in transmittance. Cycles of light rainfall and evaporation combined with a humid and salty environment led to cementation occurring on all coupons. The development of an abrasion-resistant, super-hydrophobic coating with a low roll-off angle and high water contact angle is more likely to provide an anti-soiling solution by reducing the build-up of cementation.

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Section: Cementationmentioning

confidence: 99%

Testing the Durability of Anti-Soiling Coatings for Solar Cover Glass by Outdoor Exposure in Denmark

et al. 2020

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“…However, Valerino et al (Valerino et al, 2020) reported that, even if large particles are dominant in terms of deposited mass, the soiling losses are mainly caused by the small particles. Nonetheless, Isaifan et al (Isaifan et al, 2019) showed that only a fraction of the suspended PM 10 deposits on the PV module surface and the so-called PM 10 sticky-fraction is correlated to the relative humidity through a modified sigmoid function with an inflection point at 70% RH. Above this value most of the PM is deposited, due to the action of capillary forces.…”

Section: Estimation Of Soiling From Environmental Parametersmentioning

confidence: 99%

“…Field tests showed that the dust accumulation lowers for surfaces facing toward the wind, compared with facing downwind at the same tilt angle. Isaifan et al., 2019 2019 Doha, Qatar Tropical and subtropical desert climate PM, relative humidity Showed that the fraction of the PM 10 depositing on a PV panel surface changes depending on the relative humidity. The correlation between PM and the performance ratio have an R 2 = 0.94 when using only the sticky-fraction of the airborne particulate matter concentration.…”

Section: Estimation Of Soiling From Environmental Parametersmentioning

confidence: 99%

“…Nonetheless, Isaifan et al. ( Isaifan et al., 2019 ) showed that only a fraction of the suspended PM 10 deposits on the PV module surface and the so-called PM 10 sticky-fraction is correlated to the relative humidity through a modified sigmoid function with an inflection point at 70% RH. Above this value most of the PM is deposited, due to the action of capillary forces.…”

Section: Estimation Of Soiling From Environmental Parametersmentioning

confidence: 99%

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Monitoring photovoltaic soiling: assessment, challenges, and perspectives of current and potential strategies

et al. 2021

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Soiling is the process whereby dirt, dust, and organic/inorganic contaminants deposit on the surface of a photovoltaic (PV) module. It causes significant economic losses and can have a substantial impact on the expansion of photovoltaic technologies for energy generation. The first step to address soiling adequately is monitoring, as soiling mitigation has to be tailored to the specific conditions of each PV system and no universally valid strategy exists. The main focus of this study is to assess the current state of the art in soiling monitoring, in order to help the community better understand the needs and the challenges in this area. The potentials and the limitations of each monitoring method are discussed thoroughly in the paper, with the support of original experimental data. An estimation of the future soiling monitoring market trends is also presented, with a forecasted need for tens of thousands of new soiling monitors every year.

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“…The forces mainly include adhesion forces and detachment forces (surface tension force and hydrodynamic force). For small dust particles (diameter < 500 µm), the adhesion forces are mainly van der Waals forces and the electrostatic force in dry environments, as well as the capillary force in humid environments 3,37 . The adhesion force for a single particle on a surface can be in the range of 100~300 nN, as characterized by an AFM tip 3 .…”

Section: Dust Particle Adhesion Force and Water Droplet Cleaning Forcementioning

confidence: 99%

An active self-cleaning surface system for photovoltaic modules using anisotropic ratchet conveyors and mechanical vibration

Sun

Böhringer

2020

Microsyst Nanoeng

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The purpose of this work is to develop an active self-cleaning system that removes contaminants from a solar module surface by means of an automatic, water-saving, and labor-free process. The output efficiency of a solar module can be degraded over time by dust accumulation on top of the cover glass, which is often referred to as “soiling”. This paper focuses on creating an active self-cleaning surface system using a combination of microsized features and mechanical vibration. The features, which are termed anisotropic ratchet conveyors (ARCs), consist of hydrophilic curved rungs on a hydrophobic background. Two different ARC systems have been designed and fabricated with self-assembled monolayer (SAM) silane and fluoropolymer thin film (Cytop). Fabrication processes were established to fabricate these two systems, including patterning Cytop without degrading the original Cytop hydrophobicity. Water droplet transport characteristics, including anisotropic driving force, droplet resonance mode, cleaning mechanisms, and system power consumption, were studied with the help of a high-speed camera and custom-made test benches. The droplet can be transported on the ARC surface at a speed of 27 mm/s and can clean a variety of dust particles, either water-soluble or insoluble. Optical transmission was measured to show that Cytop can improve transmittance by 2.5~3.5% across the entire visible wavelength range. Real-time demonstrations of droplet transport and surface cleaning were performed, in which the solar modules achieved a 23 percentage-point gain after cleaning.

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Evaluation of the adhesion forces between dust particles and photovoltaic module surfaces

Cited by 118 publications

References 43 publications

Testing the Durability of Anti-Soiling Coatings for Solar Cover Glass by Outdoor Exposure in Denmark

Testing the Durability of Anti-Soiling Coatings for Solar Cover Glass by Outdoor Exposure in Denmark

Monitoring photovoltaic soiling: assessment, challenges, and perspectives of current and potential strategies

An active self-cleaning surface system for photovoltaic modules using anisotropic ratchet conveyors and mechanical vibration

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