All glass companies that produce low iron glass for solar energy applications strive to optimize process related parameters in the furnace.

A high performance low iron glass exhibits absorptance of less then 1% and a reflectance of 4% on both sides of the glass, resulting in a maximum transmittance value of 91.5% for the best quality glass.

The maximum transmittance is therefore limited to 91.5%. The only way of increasing the transmittance is by reducing the reflectance. This can be done by modifying the surface of the glass, which should have a refractive index of 1.22 after modification.

Sunarc AR process

The Sunarc AR process is unique since it is a subtractive process that removes material from the glass surface. It uses the glass itself and introduces the anti reflective layer into the glass.

This surface is produced by subjecting the glass to a series of mild chemicals that produces a layer 100 nanometers thick (100 nanometer is 1/10.000 mm) on both sides of the glass. This layer has a refraction index of 1.24 and reduces the reflectance of the glass to 1.5%. The resulting increase in transmittance is 5-6%. The resulting transmittance is 96% to 97% (measured according to ISO 9050 with solar spectrum ISO9845). Sunarc Technology guarantees that its AR glass will have a minimum transmittance improvement of 5% compared to unmodified glass, and guarantees the AR surface for 10 years (see Sunarc warranty for details).

Transmittance of glass as a function of wavelength in the range 300 to 2500 nm before and after treatment. The effective wavelength regions for greenhouse (GH), PV module (PV), and thermal collector (TM) applications are illustrated in the graph.

The average transmittance for the three applications; greenhouse, PV module, and thermal collector is:





AR glass












The Sunarc AR process is environmentally friendly, since the chemicals are not consumed, and only require minimal replenishment. The production is a closed loop process, where process water is cleaned in the waste treatment system and can be released into nature with no environmental impact. The chemicals used are low in toxicity and used at low concentrations. The production process uses little energy.



Sunarc Technology A/S Industrivej 44
DK-4683 Rønnede

Phone: +45 5621 3000
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

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Sunarc Technology A/S :: Industrivej 44 :: DK-4683 Rønnede :: Phone +45 5621 3000 :: Fax +45 5621 3300 :: E-mail info@sunarc.net