I am with the National Electrical Manufacturers Association in Rosslyn, VA. Our approximately 450 member companies manufacture products used in the generation, transmission and distribution, control, and end-use of electricity.
A significant cross-section of our members supply electrical equipment for wind, solar and other installations that expose their products to sunlight. They receive many inquiries from customers who desire to know the expected life of products exposed to continual sunlight.
Currently, the most common laboratory exposure test methods are ISO 4892-2, Plastics – Methods of exposure to laboratory light sources – Part 2: Xenon-arc lamps, and ASTM G155, Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials, with exposure time of 1000 hours.
In Underwriters Laboratories standard UL 746C, Polymeric Materials - Use in Electrical Equipment Evaluations, the test procedure states:
The samples are to be exposed to 1000 h to xenon-arc, Method A, in accordance with ISO 4892-2. There shall be continuous exposure to light and intermittent exposure to water spray. The cycle shall consist of 102 min without water spray and 18 min with water spray. The apparatus shall operate with a water-cooled xenon-arc lamp, borosilicate glass inner and outer optical fibers, a spectral irradiance of 0.35 W/m²/nm at 340 nm and a blackpanel temperature of 65 ± 3º C. The temperature of the chamber shall be 45 ± 3º C. The relative humidity in the chamber shall be 50 ±5 %.
In light of the complexity of this subject, I would like to know if anyone is aware of any models that have been investigated or developed to correlate real life exposure to UV radiation from terrestrial sunlight with common accelerated laboratory test exposure methods, and if there any industry groups, professional experts or other resources who might be knowledgeable of such models?