The main impediment to increasing the purchase of electric vehicles (EVs) across the state is the sticker shock — most models are still costlier than cars with combustion engines — but it’s not the only one. The early adopters of EVs, even those with a fairly short commuting distance, increasingly have problems finding charging stations on their regular routes.

And potential buyers, hearing that, hang back from buying into the technology, worried that operating the cars won’t be practical for their transportation needs and routines.

Overcoming that hurdle is the reason lawmakers should pass House Bill 1585, a measure that would authorize the state Public Utilities Commission (PUC) to issue rebates as incentives to businesses and other entities that add to the state’s EV charging infrastructure.

Two other worthy measures are moving toward conference. One, Senate Bill 409, would establish a vehicle registration surcharge for EVs and other alternative-fuel vehicles to pay into the State Highway Fund. And SB 1000 would compel new apartment and commercial buildings of a minimum size to include stalls that are ready for chargers.

But it’s HB 1585 that offers the best prospect for progress, with rebates to be underwritten by an unspecified amount in a special fund. The duration of this finite offer is what will need to be settled, assuming the bill moves, as it should, to a conference committee.

Drawing these limits is an uncertain business. At some point the private sector should take over, fulfilling customer demand. Given the current shortage of EV chargers, though, it’s plain that this point has not been reached.

There are three levels of installations that would qualify for a rebate: installing a new charging system where none previously existed; upgrading an existing system to a “Level 2” station that serves two or more EVs at a time; or building a direct-current, fast-charging system.

The bill rightly would give priority to systems that are “publicly available, serve multiple tenants, employees, or customers, or serve electric vehicle fleets.”

It would be a wise course for the state to include a good share of fast-charging systems in the mix. Although there is typically a customer cost for recharging at such stations, they would be able to serve more vehicles in a day.

The down side? They are much more expensive to install, and some advocates say too many of this type would drain the funding source quickly. Ulupono Initiative, the impact investment firm, recommends rebate percentages of 30%, capped at $2,000, for a single-port station, 50% ($6,000) for a Level 2 station and 70% ($35,000) for a fast charger.

The conference committees that will settle all of this will need to enable the right mix of rebates; conferees should see to it that there be a report back to the Legislature in a year or two to evaluate the response and possibly make adjustments.

James Griffin, chairman of the PUC, has testified in support of the bill and recommends an appropriation of $1.2 million for each of the next two fiscal years. The commission also recommends authorization of an ongoing funding source, but perhaps that could wait until lawmakers can review this pilot program.

The state has a groundbreaking clean-energy policy, but it does not cover transportation, which represents more than two-thirds of the fossil fuels imported. An advance on this front is needed.

HB 1585 would move Hawaii forward in an area in which it is lagging. According to a study by the nonprofit Center for American Progress, 16 states have various incentives to promote EV chargers.

Hawaii is not among them. It should be.