Cleaning Alum. Panels
You can get a coil cleaner for aircond. coils at a heating and cooling supplier. You mix it 50/50 with water and spray it on with a yard sprayer or a spray bottle and then just rinse it off with water and it will take alll the dirt and discolor off and make it look new again. I use it on all my alum. parts and wheels. But you want to mix it weak for anything that has a polished finish on it or it will take the shine off.