Solar energy harvesting and a water droplet cleaning of micropost arrays surfaces

Abstract

Summary Solar energy harvesting in dusty environments initiates many challenges for sustainable operation of photovoltaic panels. Environmental dust reduces photovoltaic device performance and requires regular cleaning of active surfaces. Self‐cleaning of surfaces by water droplets offers advantages in terms of reduced cost and sustainable operation. The present study investigates dust removal from hydrophobic and optically transparent micropost arrays surfaces in relation to solar energy applications. The micropost arrays are replicated using polydimethylsiloxane (PDMS) casting on textured silicon wafers. The replicated micropost arrays result in hydrophobic surface with contact angle of about 147.6° ± 5° and the hysteresis of 16° ± 2°. In relation to self‐cleaning, water droplet behavior on the inclined replicated micropost arrays is simulated and droplet movement is examined experimentally. The optical transmittance of micropost arrays is tested in outdoor dusty environments. It is found that droplet slides on the inclined micropost surface and expanding droplet size enhances the sliding velocity. Alkaline dust compounds dissolve in droplet while increasing pH from 4.35 to 7.94 and surface tension from 0.072 to 0.120 N/m. This alters droplet pinning and lowers the sliding velocity from 0.2 to 0.15 m/s. Optical transmittance of the samples was tested in outdoor dusty environments improve considerably by sliding water droplet cleaning on daily bases (transmittance reduces only 3% or less as reference to surface being kept indoor environments). Hence, introducing micropost arrays on photovoltaic panel protective cover surface can provide self‐cleaning effect, via droplet rolling, while slightly reducing optical transmittance of cover glass (approximately 2.5%‐3%) in outdoor environments.

Avalanche effect for chemically modified dust mitigation from surfaces

“…Prevention of dust scaling and its mitigation from surfaces become one of the recent challenges, particularly in the renewable energy sector. Although several techniques have been adopted for improved mitigation dust from energy harnessing surfaces such as electrostatic shielding 9 and droplet rolling/sliding 10 ; however, cost effective mitigation method(s) is still under research. Introducing public tariff shearing the cost of dust scaling is under study 11 .…”

Liquid droplet impact on a sonically excited thin membrane

“…A liquid droplet behavior on hydrophobic surfaces remains important in various applications including self-cleaning, 1,2,3 drug delivery, 4 painting, 5 combustions, 6 and similar. Depending on the surface wetting state, liquid droplets can slide, roll, and roll/slide over the surface.…”

Water droplet can mitigate dust from hydrophobized micro-post array surfaces

“…The micro-post arrays can easily be produced on solid surfaces such as silicon wafers. In addition, the micro-post array topology created on silicon wafers can be replicated over soft material surfaces such as polydimethylsiloxane (PDMS), which can be used for self-cleaning applications 5 . The micro-post pillar spacing and maintaining hydrophobicity over the surface become critically important for self-cleaning applications.…”