Mini Power Washer
A garden sprayer can be a mini power washer for cleaning windowsills and other hard-to-reach spots. Before you fill the tank with water, be sure to rinse it repeatedly to flush out any chemical residue.
Mix Your Own Window Cleaner
You know, most professional window washers don't buy window cleaner. They mix a teaspoon of dishwashing liquid with a few gallons of water. That's it. You can just pour it in a spray bottle for in-house work. For outside windows, get yourself a sponge/squeegee combination window cleaner and dip it right in the bucket.
See how pros get windows squeaky clean fast.