Will,
Sunlight is more often than not, not the issue, it's the surface temperature of the panel.
Surface temperature rather than sunlight is the culprit at how it effects our detailing products.
Here's an article I found on how color affects surface temperature...
"The outside air temperature was approximately 80 degrees F. At 2:15pm just after measuring the cars, the pavement in the sun measured 111 degrees, shaded pavement was 72 degrees, a shaded white cinder block wall was 68 degrees, and a shaded metal wall was 73 degrees.
So this is a typical warm but not unreasonably hot day."
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Now, I always knew that a black finish was much hotter than white but personally had no idea the temperature extremes were so great.
Mid 90's is about as warm I'm comfortable to work in both personally and where I feel it affects the products performance.
If you find yourself doing a lot of work in direct sun during the heat of the day then it might be a good idea to invest in a canopy as sot of portable shade. They're portable, set up easily, and cost is minimal. May here use them and make a lot of sense to me....
This about it but in parallel investigate some of the products that can be used in direct sunlight...