For those in Colorado (and other states with Xcel), there is now a time-of-use rate plan available to enroll in. I think it's been available for a couple months, but I hadn't noticed until paying my electric bill online this week. Since Tesla allows scheduled charging, I went ahead and enrolled for TOU billing and should be converted sometime in the next 6 weeks (they have to install a smart meter at my house). The rates for CO are below. Has anyone else switched over? 8 cents per kWh overnight to charge the S seems like a no-brainer, but I suppose it depends on your overall usage. Of course, solar would be most ideal.