It depends on how much roof space (or yard space) you have, and how many panels you install. A good average system size is 24 panels, which in most cases is a PALLET of panels, which gets you the best pricing. My home has 24 panels on it. 20 of them are 230 watt panels and 4 are 240 watts, added at a later date.
My house faces South West, and I have two large hills on the East and West side that shade my roof for an hour and a half in the morning and an hour before sunset. All that considered, here’s what I just got from the electric company on my most recent bill. It tells the story. I have gas heat, so this is just for my electric usage, but that includes AC in the summer months!