Good news for drivers of electric vehicles. Hawaiian Electric Co., with the approval of state regulators, has extended discount charging rates for another year. 

Oahu EV drivers can charge their car for 6 cents per kilowatt-hour below standard rates during the off-peak hours of 9 p.m. to 7 a.m. For the neighbor islands, off-peak charging is 7 cents to 9 cents per kwh lower. 

HECO’s EV charging program is designed to encourage electricity use during the nighttime hours. Members of the program are charged more to plug in their car during the day — 3 cents to 5 cents per kwh above standard rates.

The “time of use” rates add to the savings that EV drivers are already reaping from using electricity rather than gasoline to power their cars.

“Using normal rates, the cost per mile of a plug-in EV is about half of the cost per mile of a typical (internal combustion engine) sedan,” said HECO spokesman Peter Rosegg by email. “Charging with discount rates increases the savings.”

There are other perks. EV drivers can park for free at municipal meters and garages and use rush-hour, high-occupany lanes with only one passenger. 

The adoption of electric vehicles has gotten off to a relatively slow start, despite Hawaii’s ideal environment for the cars. There are less than 2,000 EVs on the road. 

But that could change as more charging stations crop up throughout the islands and drivers become more comfortable with the technology. A recently released infographic from the Union of Concerned Scientists predicts electricity could power 40 percent of all new vehicles nationwide by 2035. 

The below data is based on average, nationwide electricity rates. Hawaii’s rates are about three times the national average, so savings are less. But Hawaii’s EV owners can reduce their charging costs even more by switching to solar panels to power their homes or charging stations. 

(Graphic: Union of Concerned Scientists)

— Sophie Cocke