You can get windows 'cleaner' by spraying water on them, but you can't get them clean without manual agitation and some method of removing all the dirt and the water. Rinsing with tap water eventually causes water spots.
The cheapest way to get windows clean is with a strip washer or brush, a six inch scraper, and a squeegee.
A water fed pole and pure water setup works great, too. A lot easier but a lot more expensive to get into.
The only alternative I have found that gives decent 'chargeable' results is to brush with a strong Simple Cherry solution and rinse, rinse, rinse. Simple Cherry is the only soap I have used that will sheet off and not leave (much) spotting.