Well that's the catch...getting the right sized system...that pays you back...in your lifetime!
I've been reading about these systems: http://www.solarmarket.com/frontier.html
But honestly, I don't know my needs. I need to research that. And have someone do a site survey to make sure this is workable for my location. My garage roof faces south and we get a ton of sunlight, so much so that we have to shut the blinds or cook during the warmer months.
With oil skyrocketing, and my state refusing to allow a nuclear power plant to be here, I just want to put a dent in the power bill. Then use whatever savings into what I'll get screwed buying heating oil

I see there are two on grid systems...one simply feeds straight out to the grid and builds a credit. The other uses an inverter to power your usage...if you arent using it, it goes out to the grid, generating a credit. I like the sounds of #2 but its obviously going to be a more expensive system.
My home is a ranch, 1-story home with a full basement. Not huge by any means, so possibly a good candidate for savings.