The Tesla Roadster is already prowling the streets while the 2011 Chevy Volt and 2011 Nissan LEAF EV are preparing to launch later this year.  That's familiar news to most, but what might be a little more hazy is how the growing ranks of EVs are getting their power.

Amid all the EV excitement, charging has been one topic that has been decidedly undercovered -- largely due to lack of available information.  However, the Michigan Public Service Commission this week announced that it had approved the state's first experimental rate for residential customers to recharge their EVs.  

Utility DTE Energy Co.'s Detroit Edison unit filed the application.  By having a regimented payment infrastructure and usage monitoring, the utility will be able to better cope with demand and presumably provide customers with more competitive rates than if it left them on their own to install home charging stations and charge off their current connections.

DTE Energy is offering EV customers two options -- either pay a flat rate of $40 per vehicle per month, or sign up for a lower, variable off-peak rate.  The big expense will be the installation of a specialized meter circuit and charging station -- DTE Energy says that customers may be charged up to $2,500 for that.  It's unclear whether automaker-provided chargers will be compatible with DTE's system.

The trial program will run through December 31, 2012 and can cover up to 2,500 consumers.

For moderately heavy drivers (40-100 miles per day), assuming $40/week in gas expenses and the full charging station cost, it looks like customers will start to see savings in about 2 years.  While those savings have a long way to go towards justifying the large cost premiums on the Volt and Leaf, they're a start, at least.