Adhesion mechanisms on solar glass: Effects of relative humidity, surface roughness, and particle shape and size

Journal Article · Thu Jul 27 00:00:00 EDT 2017 · Solar Energy Materials and Solar Cells

DOI:https://doi.org/10.1016/j.solmat.2017.07.026· OSTI ID:1375106

Moutinho, Helio R. ^[1]; Jiang, Cun -Sheng ^[1]; To, Bobby ^[1]; Perkins, Craig ^[1]; Muller, Matthew ^[1]; Al-Jassim, Mowafak M. ^[1]; Simpson, Lin J. ^[1]

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1. National Renewable Energy Lab. (NREL), Golden, CO (United States)

To better understand and quantify soiling rates on solar panels, we are investigating the adhesion mechanisms between dust particles and solar glass. In this work, we report on two of the fundamental adhesion mechanisms: van der Waals and capillary adhesion forces. The adhesion was determined using force versus distance (F-z) measurements performed with an atomic force microscope (AFM). To emulate dust interacting with the front surface of a solar panel, we measured how oxidized AFM tips, SiO₂ glass spheres, and real dust particles adhered to actual solar glass. The van der Waals forces were evaluated by measurements performed with zero relative humidity in a glove box, and the capillary forces were measured in a stable environment created inside the AFM enclosure with relative humidity values ranging from 18% to 80%. To simulate topographic features of the solar panels caused by factors such as cleaning and abrasion, we induced different degrees of surface roughness in the solar glass. As a result, we were able to 1) identify and quantify both the van der Waals and capillary forces, 2) establish the effects of surface roughness, relative humidity, and particle size on the adhesion mechanisms, and 3) compare adhesion forces between well-controlled particles (AFM tips and glass spheres) and real dust particles.

• Research Organization: National Renewable Energy Lab. (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1375106
• Alternate ID(s): OSTI ID: 1549659
• Report Number(s): NREL/JA-5K00-67734
• Journal Information: Solar Energy Materials and Solar Cells, Vol. 172, Issue C; ISSN 0927-0248
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
soiling mechanisms
Van der Waals forces
capillary forces
relative humidity
surface roughness
dust particles