Hi Mark,
No, I haven't done any more research/measurements (it's been winter here) but I believe that most commercial sensors use PTFE (Teflon). Having just examined the apalling state of some of the plastic fittings on my conservatory roof, I'm satisfied that something "special" like Teflon is necessary for resistance to weather/sun.
So my recommendation (still) is to use Teflon sheet as both protection and as a diffusing window (for the correct cosine response). To determine the effective attenuation/transmission of the Teflon, just point the surface of the PV panel/sensor directly at the sun, with and without the sheet inbetween and compare the reported values.
Cheers, Alan.
No, I haven't done any more research/measurements (it's been winter here) but I believe that most commercial sensors use PTFE (Teflon). Having just examined the apalling state of some of the plastic fittings on my conservatory roof, I'm satisfied that something "special" like Teflon is necessary for resistance to weather/sun.
So my recommendation (still) is to use Teflon sheet as both protection and as a diffusing window (for the correct cosine response). To determine the effective attenuation/transmission of the Teflon, just point the surface of the PV panel/sensor directly at the sun, with and without the sheet inbetween and compare the reported values.
Cheers, Alan.