I wash mine (and machine polished yesterday) in direct sunlight and had no issues with getting high quality results. Just don't let the panels dry so the moment you finish the final rinse drop everything like your balls are on fire and start drying with your MF and detailing lube spray 
Also at this point, a damp MF works best for streak free windows, no need for window cleaners at all.

Also at this point, a damp MF works best for streak free windows, no need for window cleaners at all.
Mine shine and I only use cleaners on the inside every few months.
. Plenty at the Cribbs store if anyones interested.

and it kept dropping its crap on the car, so it might help a bit in that respect