Are you sure that $ 0.07 is your total electricity cost or is it your shopping price? Where I live electricity is advertised @ $ 0.079 per kilowatt but that does not include distribution, transmission and other  charges. So while it is listed @ $0.079 it is more around $0.14. That's almost double the quoted price. Just look at your power bill real close and deconstruct it with math. Otherwise you are going to be setting yourself up for a disappointment.