I used to work in Sydney, we worked from 5 a.m. till 9 a.m. end of shift! The problems were sun & wind.
I never did any domestic, but windows stay cleaner for the fly screens. I have the same problems here in Spain. My clients are mainly English, as I can't compete against the spray on cleaners for €5 an hour.
You can clean windows in the sun, you just section areas off & do a couple of square metres at a time. I always take a note which clients are morning or afternoon cleans, depending which way they face!