Most solar energy based applications used to generate electricity or heat use specialized glass with greater transmittance than ordinary soda lime glass (window glass).
Glass manufacturers increase transmittance by changing the chemical composition of the glass, in particular by reducing the iron content of the glass.
There are two main types of plate glass; float glass and rolled glass.
Float glass is made by floating molten glass on a bed of molten metal. The process creates a perfectly smooth and even surface. It is however difficult to achieve transmittance values over 90% using this method of production.
Float glass is used where light needs to be transmitted without changing the angle of the light beam. This is necessary when building concentrating PV modules.
For greenhouse applications float glass is predominant.
Rolled glass is used increasingly in PV modules and thermal collectors because of its higher transmittance. There is little cost difference between rolled and float glass.
Rolled glass is characterized by its macroscopic structure. This production process is designed to produce high performance low iron glass resulting in a transmittance that is typically slightly above 91%.
The rollers can imprint a surface structure on the surface of the glass. Different surface structures are chosen depending on the intended application. A burred surface structure is often used to enhance adhesive strength between EVA and glass in PV applications.
Structured glass is used in both PV and thermo solar applications.
Sunarc can produce an AR surface on both tempered and untempered glass. This process does not affect the properties of the tempered glass.
Sunarc prefers to use tempered glass for safety reasons. Almost all glass that Sunarc processes is tempered (99%).
All tempered glass is produced to meet the international standard EN 12150-1:2000.
Sunarc is not a glass producer but works closely together with a number of glass manufacturers in Europe and China. We have built up good relations with them over the years. All our glass suppliers produce high quality low iron solar glass that meets the most demanding criteria for solar energy applications.