I've talked with Mt Hardware Mike a few times about his return on investment and he indicated that the current system will pay for itself in about 10 years.
If you're thinking about putting in a system to generate an income it isn't going to work. To be cost effective it needs to be looked at long range. To pay for Mike's system in a 10 year period seems like a smart move in my books.
I'm seeing plenty of uses for solar power popping up everywhere. Go into any garden center and look at how many walkway lights are now solar powered. There's outside night lights, house number lights, remote cell phone booths and the list goes on.
Could you completely get off the grid? Probably not at this point as we have too many modern conveniences that require large current demand. As technology continues to develop and prices drop it might be possible.
Speaking about new uses for solar energy: This summer we developed the first of it's kind solar powered wildlife live cam. The infrared camera and radio transmitter are located in a remote forest area where Edison power just wasn't an option. The camera is being used in the Bighorn Sheep Restoration project taking place in our San Gabriel Mountains.
Solar energy has allowed us to study daily habits of bighorn sheep without disturbing the environment. If you'd like to see more about our Wrightwood solar power project:
http://www.wrightwoodcalif.com/bighorn/
This remote camera technology has been proposed for use on the Highway 39 Bighorn Sheep Study by Caltrans.