best low light performance

harold1946 wrote:

HiTech wrote:

harold1946 wrote:
One of the main reasons for early failure with all PV made by Unisolar is that the protective coating for both their rigid and flexable panels is plastic. UV destroys plastics, and it has to pass through that before reaching the cells.

Actually I think it's the other way around. I believe the plastic lense on the front of Unisolar units is heavily UV stabilized, resulting in the lower efficiency rating per square meter, because some of the light energy is absorbed by the stabilizing additive in the polymer coating.

UV stabilizer

Jim

That is one of the points I have been trying to make. The stabelizers used, reduce the efficiency at all times.
I do not know whether the stabelizers are applied as a topcoat or as an ingredient in the polymer.
Another possibility for reduced efficiency may be refraction caused by the stabelizing agent. Interesting.

Yes the UV stabilizer which stops UV degradation does make the efficiency per unit area (which is not positively correlated to efficiency at low light levels per nominal watt of power) less. We all agree poly and Unisolar panels take more space for a given wattage. The UV protection specifically absorbs UV frequency radiation, which is minimal at low light levels. So Unisolar panels have a huge surface area per watt to collect non UV light, much the way that a larger camera lense does better in low light. So possibly their low efficiency per unit and consequent large size per watt, may be exactly the specific reason they do better at low light levels. Huge light collection area per watt, and a non-clouded transparent coating that passes the frequencies of light that are most abundant in low light situations.

Jim