Naperville homeowners on the city's municipal electric grid could see their utility rates change every three months if the City Council ultimately decides to leave its current power provider and buy electricity on the open wholesale market.

The council's next presentation on the topic is scheduled for Tuesday, Aug. 18, the fourth in a summer-long series exploring what happens after Naperville's contract with the Illinois Municipal Electric Agency expires in 2035.

The price of entry keeps getting clearer. As we reported Aug. 6, City Manager Doug Krieger told the council at its July 21 meeting that joining the PJM Wholesale Market as a direct buyer would require roughly $24 million in deposits, based on two months of peak electric use, plus a $15 million rate stabilization fund. Combined, that's up to $39 million the city would need to set aside before buying its first megawatt on the open market.

"The $12 million figure was for one month, but typically they would require two months of your highest electric use. So for us it would be about $24 million," Krieger said at the July 21 meeting, according to NCTV17.

The tradeoff for that upfront cost: potential savings. An analysis by advocacy group Sustain Naperville found IMEA costs were 43% above market rates through November 2025, a finding the group says aligns with conclusions from the city's own consultants.

But cheaper power comes with a catch. Under the open-market model, wholesale prices fluctuate with demand, weather and fuel costs. Krieger warned at the July 21 meeting that the council would "likely need to review and evaluate rates on a quarterly basis with this option, just due to the volatility."

That means Naperville electric customers, who currently see rate adjustments on a longer cycle under IMEA, could face bill changes four times a year.

Councilman Patrick Kelly, who is not seeking re-election after eight years on the council, pressed staff for details on how other communities protect against price spikes. "I would hope nobody's just thinking about straight market purchase with no hedge at all," Kelly said at the same meeting. "That would not seem to make sense."

Councilwoman Mary Gibson noted the city already pays for energy management through its IMEA membership fees. Under the open-market model, Naperville would need to staff or outsource its own energy management office, but Gibson argued the cost would shift rather than appear from nowhere.

Councilman Josh McBroom, a financial advisor first elected in 2023, pressed Krieger on an anticipated 2028 rate increase that would help build the stabilization fund.

Only one U.S. city, South Sioux City, Nebraska, has closely adopted the straight-market model Krieger described, hiring a private firm as its market manager.

The council voted 6-3 on Feb. 3 to pause negotiations on extending the IMEA contract beyond 2035, launching the current review series. The presentations are expected to culminate in a strategic workshop later this year.

No per-household dollar estimate of what quarterly rate changes would mean for a typical Naperville electric bill has been released by the city.

Residents who want to weigh in can attend the Tuesday, Aug. 18 council meeting or submit public comment at naperville.il.us/speakersignup.