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.