Ahh, apart from being a newbie at window washing, I'm an expert at vehicle cleaning equipment and chemicals.
I'd say, be very careful with TFR type products, most will stain glass, and will definitely stain if it dries on anywhere at all in the sun.
A very very good and great value cleaner that works well is Autosmart G101. If you know any car valeters or garages that buy from the local Autosmart rep (goes round in a truck) ask them to get you some - around £14 for 5Ltrs. To be diluted 30:1 so goes a LONG way.
Same as with TFR though, don't be tempted to mix too strong, it can easily stain glass.