Did you ever come across questions like: Will the transparent cover of the LED modules colorize because of sunlight? Is this electrical housing build of the right materials to withstand the effects of changing weather? Will this painted surface withstand the impact of UV light and rain?
The impact could exist of colorization (see image below of a partly exposed plate), fading, chalking, cracking, crazing, hazing, blistering, gloss loss, strength loss and embrittlement. Therefore, it should be considered to execute a solar test for any material that is exposed to natural or artificial sunlight during lifetime. With solar/ weathering tests it is possible to produce the impact of sunlight on materials in several days, weeks where testing under environmental conditions takes years.