Silicon modules

The most common type of photovoltaic modules is made of silicon cells laminated to solar glass. These PV modules are normally marketed based on their performance rating under Standard Test Conditions (STC). This is done by flashing the modules according to STC norms. For a high quality low iron solar glass 4% of the light is reflected by the front surface and 1% is absorbed by the glass. The glass is laminated to the silicon cells with EVA that has a refractive index of 1.5 which is similar to glass. This means that no light will be reflected by the inner surface of the glass.

Transmittance of glass as a function of the wavelength range 300 to 1150 nm before and after AR treatment for PV applications. A solar spectrum is also illustrated in the same graph. The integrated PV transmittance before and after AR treatment is:



AR glass






The improvement in the transmittance after AR treatment is 5.7%. The performance improvement for a PV module where the glass is exchanged with Sunarc AR glass is:
5.7% / 2 = 2.85%. 

If Sunarc AR glass is used the reflectance from the outer surface is reduced by 2.5 to 3.0%. As a consequence of this the transmittance increases by 2.5 to 3.0%. Based on STC conditions that use an irradiance of 1000 W/m², 25 to 30 W more light per m² will reach the cells. Depending on the conversion efficiency of the module the increase in the power is 3.5 to 4.5 peak Watts. The advantages of AR glass depend to a large degree on the conversion efficiency of the PV module. The higher the PV module conversion efficiency the greater the benefit.

The AR treatment of the inner glass surface has the added benefit of improving the bonding between the glass and the EVA. This reduces the risk of delamination during the lifetime of the module.

Concentrating PV modules

For concentrating PV modules both surfaces of the AR glass contribute to the increase in the performance. The transmittance increases by 5 to 6% with a corresponding increase in power. The performance improvement for the glass exemplified above would be 5.7%.



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DK-4683 Rønnede

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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