Investigation of solar cell cover glass surfaces after long-term exposure to desert climate in Southern Algeria

During long-term operation, solar cell cover glasses are exposed to harsh environmental conditions, potentially causing significant surface damage and modification. Against this background, the main objective of the present study is to investigate and characterise the chemical and physical alterations occurring on solar cell cover glass surfaces after prolonged exposure to desert climates. For this purpose, complementary spectroscopic techniques, namely laser-induced breakdown spectroscopy (LIBS) and X-ray photoelectron spectroscopy (XPS), were employed to provide detailed insights into surface modifications and contaminations. Specifically, cover glasses installed for 25 years in the Southern Algerian desert were examined using scanning electron microscopy (SEM), LIBS, and XPS. Apart from mechanical damage such as chipping, adhesion of (hydro) carbonaceous dirt and sand grains, and accumulation of organic herbaceous structures at the outermost surface, significant changes in the chemical composition of the near-surface glass layer were observed. These changes include carbon penetration into the surface and noticeable leaching of key glass constituents such as calcium and magnesium, both effects attributable to prolonged exposure to desert climate. Additionally, notable surface contamination by tin and lead was identified, likely resulting from impurities introduced via the liquid metal bath used during the float glass manufacturing process. It turns out that both influencing factors, manufacturing and exposure, cause an accumulated modification of the investigated glass surfaces, subsequently affecting their optical properties. Such modifications ultimately have implications for the overall efficiency of the embedded actual photovoltaic cell.