Naperville runs its own municipal electric utility. That affects your net metering terms, how you should size a system, and how quickly it pays back.
Almost every guide to solar in Illinois assumes you are a ComEd customer. In Naperville that assumption is simply wrong, and the difference is large enough to change how you should size your system.
The City of Naperville buys and distributes its own electricity through a municipal utility. It sets its own net metering policy. Cross the boundary into Aurora, Lisle, Wheaton or Downers Grove and you are on ComEd, under Illinois’ statutory rules instead.
How Naperville credits your exported power
Naperville credits energy you export one kilowatt-hour for one kilowatt-hour against the electric-utility portion of your bill. Credits accumulate month to month, which lets summer production offset winter consumption.
The catch is what happens at the end of the cycle. Unused credits expire every March 31. Whatever is left is paid out in April at the avoided-cost rate — around 4.9 cents per kilowatt-hour, a fraction of what you pay for retail power.
The practical consequence
Over-sizing a system is penalized in Naperville. A system built to bank a large annual surplus will have that surplus cashed out cheaply each spring rather than carried forward. Size to your actual annual usage.
In ComEd territory, surplus keeps its value
Under Illinois’ statutory net metering, ComEd credits exported energy at the full retail rate. A kilowatt-hour you export in July offsets a kilowatt-hour you import in January at equal value. For surplus production, that is a materially better arrangement than the municipal terms next door.
The counterintuitive part: cheaper power, slower payback
Here is the twist most homeowners do not expect. Naperville’s municipal electricity is cheaper than ComEd’s — the average residential bill runs around $122 a month for roughly 844 kilowatt-hours, meaningfully below surrounding communities.
That is excellent for your monthly bill and awkward for solar economics, because solar earns its return by avoiding retail power. When power is cheaper, every kilowatt-hour your panels produce is worth less. Combined with the credit expiry above, the same system genuinely pays back more slowly in Naperville than in the ComEd towns a few miles away.
We would rather say that plainly than pretend otherwise. It does not mean solar is a poor decision in Naperville — large homes with high usage still do well, and Naperville has many of them — but it does mean your bill matters more than your roof when deciding.
Permits are a City process too
- Your solar permit comes from the City’s Transportation, Engineering & Development (TED) Business Group, filed through the City’s online permitting portal.
- A signed City interconnection agreement is required before the system can be energized — separate from the building permit, and a common cause of delay when it is missed.
- Illinois Shines REC payments are unaffected: municipal utility territories are eligible to participate alongside ComEd customers.
General information, not tax or financial advice. Incentive programs and utility rules change — confirm current terms with your installer and the relevant program before making a decision. See our 2026 Illinois incentives breakdown for the current figures.