State utility regulators, sorting out how to manage the low-emissions value of electricity used in residential electric-vehicle charging, have ordered Portland General Electric and PacifiCorp to sign up as Clean Fuels Program credit generators.

It’s the first step in a process that could lead to annual rebates for EV drivers through the emissions-reduction program.

Clean Fuels launched at the beginning of 2016, but utilities have held off on jumping in as credit generators, awaiting guidance from…