SAN FRANCISCO — A California utility is paying drivers of BMW electric cars to delay charging their vehicles when the power grid is under pressure.

One hundred owners of BMW’s i3 hatchback receive $1,000 upfront to participate in Pacific Gas & Electric Co.’s 18-month trial, which is confined to the San Francisco Bay Area. Peter Berman, a 70-year-old, semi-retired Los Altos psychologist, was selected from about 400 applicants.

“My understanding is that we’ll get a text message that says ‘Hey, you’re charging your car right now, can you back off for an hour?'” said Berman, who began leasing his $40,000-plus i3 in October. “This is the wave of the future. We can’t continue to be dependent on gas and oil and coal for our energy use. I’m really curious as to how this is all going to unfold.”

The PG&E-BMW pilot is one of myriad experiments under way worldwide as utilities try to anticipate what will happen if (or when) millions of electric vehicles pour onto city streets and highways.

Power companies see both challenge and promise. Yes, electric cars could put more pressure on the grid if everyone plugs them in at the same time. But utilities could also tap batteries for backup power when the grid is under strain or temporarily knocked out in an emergency, paying drivers for the electricity harvested from their parked cars.

PG&E estimates that there are 65,000 electric vehicles in its vast northern California service territory, more than any other utility in the U.S. The iChargeForward pilot with BMW is an extension of PG&E’s so-called demand response program: asking industrial customers and large building owners to cut back on electricity use when demand exceeds available supply.