Than you have to keep the panels clean so they can use what sunlight
falls upon them. Many homeowners don't like washing windows so I doubt
you will see many on there roofs washing the solar panels.
In A Popular Science I read recently there was A wind generator for
the home. It cost around 20K installed as I remember. It seems A more
viable alternative than solar panels in the generation of electricity
and at least you don't have to clean it!

H.R.
"Where, exactly, am I going and why am I in this hand basket?"