High transmission float glass for solar applications

Antireflective quarter-wave single layers with an improved abrasion resista nce were prepared from sols by dip coating of float glasses, which can be u sed 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 pr e-annealed film, which allows to treat it even at temperatures neccessary f or glass strengthening. A heat treatment above 600 degrees C improved the a brasion resistance, but was not accompained by a reduction of the pore volu me as would commonly be expected. The resulting porous film therefore showe d the required effective refractive index of < 1.3, and increased the trans mission of such coated low-iron glass up to 99.6% in the visible spectral r ange and 97.0% in the solar spectral range.