Anti-reflective coating

The wavelenght of energetically usable light ranges between 400 and 2.500 nm. Only 90% of the incident light passing through glas without anti-reflective coating arrives at the solar cells.

Photovoltaic modules suffer from reduced conversion efficiency before the sun's light even reaches the solar cells. The protective front glass cover of a solar module reflects some of the incident sunlight. For a typical glass panel, depending on the time of day 4% to 15+% of the incoming light is lost due to reflection. With light travelling through the glas another 2% gets lost due to absorbtion and diffusion.

High quality photovoltaic-modules are surfaced with diaphanous glass and an anti-reflective coating on the outside.

The application of an anti-reflective coating can deliver an additional 0.3%-0.6% power conversion.

Optical reflectance - Improving transmission

Optical reflectance is a phenomenon when light propagates across a boundary between two media with different refractive indexes.

Anti-reflective layers help to minimize the differences in these indexes.

The coating is made of silicon dioxide and titanium dioxide nanorods positioned at an oblique angle. Tiny layers of altogether 50 to 100 nanometers in height, result in an anti-reflective glass with a transmission of 98% or higher and a low level of rest reflection.

Light Transmission vs. Solar Inclination

Throughout the day - morning, evening - and the through the year - summer, winter - the incident angle of sunlight changes.

In Europe for example the solar altitute during summer reaches 60°-65° whereas in winter solar angles are as low as 13° - 18°.

At an incident angle of 70° anti-reflective coated glass allows up to 85% of the incoming light to passe through to the solar cells.

Find out the sun path and solar altitude for your U.S. location. 

Click here » Sun path