I'm generally good at physics, but electricity has always been one area that confuses the crap out of me. I'm on summer vacation right now and I wanted something to do so I was thinking of building some home made wind turbines and solar panels for generating electricity. I wanted to compare the cost of building these things and how much power they produce versus what the electric company charges, just so I can find out exactly how long I would have to run the things to see if I would ever repay the costs of them based on electricity savings. So if I have some solar panels that run at 18 volts and 3 amps, that's 54 watts. The power company sells energy in terms of "kilowatt-hours" so how exactly do I determine watt-hours from just watts? If it runs at 54 watts for 1 hour straight is that 54 watt hours?