Last year, before the first of a new group of electric vehicles hit the Chicago market, regulators expressed concerns about the impact gas-free cars could have on an aging electrical grid. If electric car owners were to plug in at the wrong time of day, when energy is at its peak demand, the added burden on the electrical grid could spike energy prices and force higher-polluting generating plants to work overtime, they opined.
Industry watchers say 80 to 90 percent of plug-in vehicle charges are likely to occur at home and high-tech home chargers are outfitted with technology that can detect the cheapest time to switch on. Both ComEd and Ameren have long included so-called "realtime pricing" as an option for homeowners who prefer to pay a variable rate for electricity — creating the potential for rock bottom prices at certain times of day — rather than the standard flat rate. But many consumers still don’t know the program exists.