The Illinois Commerce Commission has asked the state’s three major electric utilities to assess the impact that plug-in vehicles could have on ratepayers.

With the first major plug-in vehicle rollouts scheduled for next month, it is still unclear how much ratepayers in Illinois will pay to charge those vehicles or what upgrades will be needed to the state’s electrical infrastructure. The ICC said Wednesday that utilities have been asked to report back by December about the vehicles’ potential impact in a white paper that will guide a new statewide committee established to prepare for the vehicles.

Acting ICC Chairman Manuel Flores said The Plug-In Vehicle Initiative, co-chaired by Flores and Commissioner Erin O’Connell-Diaz, will establish stakeholder working groups to develop best practices for Plug-in Vehicle deployment. Following the utilities’ reports in December, Flores said, the committee will look at everything from how plug-in vehicles will affect gas stations to how much drivers should pay for a charge, issuing a final report to the ICC by Spring 2011.

“We want to make sure that we are developing the right kinds of policies, especially if our policies are going to have an effect on the kinds of infrastructure people are investing in,” said Flores. “We’re not just looking at the regulatory component, but there’s also taking an interest in how this affects economic development in the state of Illinois.”

In Chicago – where about 100 public charging stations are expected to be deployed through a U.S. Department of Energy Clean Cities grant by 2012 – an Electric Vehicle Consortium includes Commonwealth Edison, government officials, alternative-fuel makers, i-Go and Zipcar. The metro area is the third-largest U.S. auto market, and Illinois ranks in the top 10 states for hybrid vehicle registrations, according to the Environmental Law & Policy Center.

ComEd is investigating the potential impact that electric vehicles could have on the grid and may consider transformer upgrades in certain neighborhoods where multiple vehicles are charging at once.

Illinois is not among the first states that companies like Nissan and Chevy have chosen for their initial rollouts of electric vehicles, but policymakers say they are hoping that their efforts will “encourage manufacturers and distributors of these new products to focus on the Illinois economy” and position the state to take advantage of federal incentives designed to spur adoption of “green” transportation.

“We think this will bode well for us in that it will get the attention of the private sector,” Flores said.