Aresearch team in China has developed a bilayer transparent conductive film for non-contact electrostatic dust removal from solar panels.
The approach combines single-walled carbon nanotubes (SWCNTs) with magnesium fluoride (MgF2). SWCNTs provide electrical conductivity while maintaining high optical transparency, but their relatively rough surface can promote dust adhesion. The researchers said that adding an MgF2 layer smooths the surface and facilitates dust removal.
“This study investigates the effects of MgF2-layer thickness on the optical, electrical, surface, and electrostatic dust-removal properties of SWCNT/MgF2 bilayer films deposited on photovoltaic glass,” the group said. “The films were fabricated by first forming a conductive SWCNT network through bar coating and then depositing MgF2 layers of controlled thicknesses by electron-beam deposition.”
The researchers fabricated the bilayer films on 50 mm × 50 mm × 0.7 mm glass substrates. They dispersed the SWCNTs in water with a dispersant and film-forming aid, applied the mixture to the glass via bar coating, and then annealed and rinsed the films.
They subsequently deposited MgF2 via electron-beam evaporation at thicknesses of 40 nm, 80 nm, 120 nm and 160 nm. An SWCNT film without an MgF2 layer served as the control sample.
After characterising the films’ surface, optical and electrical properties, the scientists placed the coated glass over a PV cell for cleaning tests. They used natural sand collected from the Kubuqi and Tengger deserts in Inner Mongolia and the Taklamakan Desert in Xinjiang.
The researchers then used an external DC power supply and a metal plate positioned 1 cm above the grounded coating to generate an electric field. They measured the proportion of sand removed and the PV cell’s power output following cleaning.
The results showed that an MgF2 thickness of 80 nm to 120 nm provided an effective balance between optical, surface and electrostatic cleaning performance. According to the researchers, moderate MgF2 deposition preserved the continuous SWCNT network while improving surface uniformity, reducing root-mean-square roughness from 5.316 nm to 3.747 nm.
“With increasing MgF2 coverage, the water contact angle increased to 111°, while the total surface energy decreased to 19.68 mN/m,” the group said. “As a result, the self-cleaning rate increased from 65.01% to 78.68%, showing that MgF2 helped reduce dust-particle adhesion and promoted dust removal under water rinsing.”
MgF2 deposition also improved the films’ optical properties, although thicker layers resulted in greater losses in electrical conductivity.
“The highest transmittance was 91.4%, while the haze was reduced to a minimum of 0.12%,” the researchers said. “The electrostatic dust-removal rate rose from approximately 84.08% for the uncoated SWCNT film to 96.36% after MgF2 deposition, and the normalized photovoltaic power-generation efficiency measured after cleaning reached 91.97%.”
The researchers concluded that the 80 nm coating offered the best compromise between optoelectronic properties and dust-removal performance. They said the 120 nm coating was preferable when higher transmittance and PV power-output recovery were prioritized.
The research, “Thickness-engineered SWCNT/MgF2 bilayer transparent conductive films for coupled antireflection and electrostatic dust removal on photovoltaic panels,” was published in Materials & Design.
The research team included scientists from North China Electric Power University, State Grid Sichuan Electric Power Research Institute, Yingli Energy Development and Hebei University.
From pv magazine Global
This content is protected by copyright and may not be reused. If you want to cooperate with us and would like to reuse some of our content, please contact: [email protected].
Comments
Please login to comment
The new issue of pv magazine Global is out now!
Available in print and digital – get your copy today!
You have no items in your basket.
