SPF Testing – Optical Properties
The performance of thermal collectors and PV modules depends significantly on the glass used. The measurement and certification procedure developed at SPF is internationally recognized as a reference and evaluates the specific properties required for good solar glass.
- Optical transmission
Transmission measurement for wave-lengths in the range 0,29 µm to 2,5 µm. For PV applications the transmission measurement can be corrected for the reflection at the glass rear surface.
- Weighted transmission
Calculation based on the optical transmission measurement and different weighting spectra result in specific rating numbers; for example the solar transmission from a weighted integration with the AM1.5 solar Spectrum (ISO 9845-1).
- Incident angle modifier
Determination of transmission in relation to the angle of incidence.
Specific measurement equipment is used for solar thermal or pv applications.
Absorptance measurement for wave-lengths in the range 0,3 µm – 18 µm and determination of solar absorptance (absorptance α) through weighted integration with the AM1.5 spectrum (ISO 9845-1).
Emittance measurement for wave-lengths in the range 0,3 µm – 18 µm and calculation of thermal emittance through weighted integration with the spectrum of a black body at a temperature of 100 °C (emittance ε).