The company I work for is interested in using solar panels. What are the best resources on the web for info?

I think it is a great idea and would love for this company to get these panels. I am the sole person in charge of retrieving info though, and want to make a convincing argument. The owner wants a realistic number of how much it would cost to go solar powered. Also, we are located north of Chicago if that makes a difference. Any info would be appreciated!