The In My Backyard (IMBY) tool from NREL enables anyone to estimate how much electricity could be produced through solar and wind power in their own backyard. This tool uses Google Earth and all you need is an address to get started!
Once you specify the area on the map that will be devoted to solar and confirm system specifications such as tilt angle, the tool calculates: 1) the amount of electricity (kWh) generated by this system each month and the value of that electricity, 2) the estimated cost and payback period, 3) the estimated solar electricity production compared with average electricity consumption for your region (or you can upload your own electricity consumption data).
Your students would have fun with a homework assignment where they analyze their home or a local farm or business for its solar potential.
Also try the PVwatts Calculator which will phase out the IMBY tool at the end of 2013.