High transmission float glass for solar applications

Abstract

Antireflective quarter-wave single layers with an improved abrasion resistance were prepared from sols by dip coating of float glasses, which can be used for covering solar cells and collectors. The coating sols are based on tetraalkoxysilane hydrolyzed in the presence of different organic additives, eg. polymers. This kind of sols lead to a stable pore structure in the pre-annealed film, which allows to treat it even at temperatures neccessary for glass strengthening. A heat treatment above 600 °C improved the abrasion resistance, but was not accompained by a reduction of the pore volume as would commonly be expected. The resulting porous film therefore showed the required effective refractive index of < 1.3, and increased the transmission of such coated low-iron glass up to 99.6 % in the visible spectral range and 97.0 % in the solar spectral range.