Savings Will Vary
Anair recently took a stab at analyzing special EV rate plans from major urban utilities and found that such plans exist in at least 14 states. His benchmark was $100 a year in savings versus the utilities' standard household plans.
The plug-in car charging rate comparison on page 25 of the Union of Concerned Scientists' recent "State of Charge" report assumed that the EV or PHEV was driven 30 miles a day at an efficiency level of 3 miles per kWh and was recharged at 240 volts.
The biggest savings were in California, where electricity rates are among the highest in the nation.
Topping the list was the separately metered EV time-of-use plan offered by Pacific Gas and Electric Co., which serves the San Francisco and Silicon Valley region. Owners there could realize savings from $1,006 to $1,068 a year by switching from PG&E's standard rates to the EV time-of-use rate.
The biggest savings outside California were for New York City customers of Con Edison: $342 a year using either a whole-house time-of-use plan or a separately metered EV time-of-use plan.
At the bottom of the list, Boston-area customers of NSTAR Electric could save $100 a year using either the utility's whole-house time-of-use plan or its separately metered time-of-use plan.
As cars with plugs become more common, utilities, automakers and electric-drive proponents are likely to get their acts together and make charging rate information a lot easier to find.
Meanwhile, the best advice is to call your local utility and ask for help in figuring out the best plan for your circumstances. And remember that just as with fuel efficiency, your savings may vary.