Glass composition of photovoltaic modules

The remaining 20 –25% encompassed fiberglass (including reinforcement, insulation, and mineral wool fibers) and specialty glass manufacturing . Flat glass transparency, low-iron glass improves photovoltaic (PV) panel efficiency. This seg- emphasis on energy efficiency and sustainability. Refs. [35, 36].

Glass is used in photovoltaic modules as layer of protection against the elements. In thin-film technology, glass also serves as the substrate upon which the photovoltaic material and other chemicals (such as TCO) are deposited. Glass is also the basis for mirrors used to concentrate sunlight, although new technologies avoiding glass are emerging.

For solar applications the main attributes of glass are transmission, mechanical strength and specific weight. Transmission factors measure the ratio of energy of the transmitted to the incoming light for a specific glass and glass width. Ratio of the total energy from an AM1-5 source over whole solar spectrum from 300 - 2,500nm wavelength.

We begin with a discussion of glass requirements, specifically composition, that enable increased solar energy transmission, which is critical for solar applications. Next we discuss anti-reflective surface treatments of glass for further enhancement of solar energy transmission, primarily for crystalline silicon photovoltaics.

Typical dimensions of a domestic PV module are 1.4–1.7 m 2, with >90% covered by soda–lime–silica (SLS) float glass. 9 The glass alone weighs ~20–25 kg since the density of SLS glass is ~2520 kg/m 3. This presents engineering challenges as current solar panels are rigid and need strong, heavy support structures.

Solar applications require flat glass. So-called Pattern Glass is mostly used as front glass in crystalline modules, whilst float glass is used for both substrate and back glass in thin-film modules. Molten glass is slowly cooled and fed off from the motlen tin.