Enhancing solar photovoltaic efficiency with porous silica coatings
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Date
2025
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University of Namibia
Abstract
Solar surface glass is known to exhibit reflectance loss of no less than 4%, depending
on the angle of the incident light. Furthermore, the high operating temperature of the
solar photovoltaic (PV) module also reduces the solar PV module efficiency by
approximately 0.45 − 0.50 %/℃ depending on the temperature coefficient and the
type of the solar modules[1]. The study investigated porous silica which is known to
have high transmittance in the solar spectrum range (0.3-1.1μm) and high emissivity
in the mid-infrared range (8-13μm) due to its bonding structure. The research
employed the base/acid double catalysis technique of the sol-gel method, using
Pluronic F127 as a surfactant, Tetraethylorthoxysilicate (TEOS), ethanol, hydrochloric
acid, ammonium hydroxide, hexamethyldisilazane (HMDS) and distilled water to
synthesise silicon dioxide sol. The sol was afterwards spin-coated on a glass substrate,
resulting in a porous silica layer approximately 200 nm thick. Scanning Electron
Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR),
and Ultraviolet-Visible-Near Infrared Spectroscopy (UV-Vis-NIR) spectrophotometer
were employed to investigate the optical characteristics of the coatings. The study
achieved an approximate 2% increase in transmittance within the solar spectrum (0.3-
1.1μm) with a single porous silica layer with 8% emissivity in the mid-infrared range
(8-13μm). In addition, it observed a nearly 20% enhancement in emissivity with three
layers in the mid-infrared range (8-13μm), while transmittance in the solar spectrum
(0.3-1.1μm) decreased almost linearly by 8% from 0.3-0.55μm with three layers
Description
A thesis submitted in partial fulfillment of the requirements for the Degree of Master of Science in Renewable Energy
Keywords
Porous silica, Sol-gel method, Anti-reflective coating, Radiative cooling, Transmittance, Emissivity, Namibia, University of Namibia