Utilities are keeping a close eye on power demand—via smart meters—to identify neighborhoods that need an upgrade. They’re also working with automakers to get customers to tell them when they buy an electric vehicle—an approach that’s identifying about 40 percent of new electric cars for Southern California Edison.
Utilities say that the upgrades they’ve performed so far would have been made anyway as part of routine grid modernization. But telling the utility that you are buying an electric vehicle essentially brings your neighborhood to the top of the list. The upgrades are paid for by all rate payers, not the electric car owners.
Both PG&E and Southern California Edison are also working to avoid grid problems by offering special rate plans for EV owners. These give customers discounts for charging at night, during off-peak hours.
Electric cars can typically be programmed to charge at certain times, rather than just charging as soon as they’re plugged in. If car owners set their cars to be completely charged by a certain time, say 6 a.m., this has the effect of staggering when cars start charging. The start time depends on how depleted the battery is—to finish at 6 a.m. might require starting at 2 a.m. or 4 a.m., depending on how much charging is needed. So instead of a surge of power demand when people get home from work, the charging is spread out through the night.
It’s technically possible for utilities to communicate with cars to have them start charging when there’s excess power being produced, and stop when there’s a peak in demand. That way, utilities could use electric cars to help stabilize the grid, and avoid the need to use inefficient “peaker” power plants. Utilities could pay electric car owners to let them do this.
But such an approach depends on the choices that electric car owners make. If everyone decides to charge at home right away, and to charge at the fastest rate possible, that could strain the grid.
So far, it looks like most electric vehicle owners are often choosing to charge their vehicles slowly and at night, according to a study of electric vehicle owners by Southern California Edison. But as fast-charging, all-electric cars like the Model S sell in larger numbers, and as automakers seek to differentiate their electric cars by how fast they charge, that story could change.