Do Data Centers Increase Electricity Bills?

By Naperville Guide · Published October 7, 2026

Short version: do data centers increase electricity bills? They can — mostly through wholesale power markets, not your meter. But Illinois has spent the last year building guardrails, and Naperville has a local twist most national articles miss. Let's walk through it.

How data centers can push your bill up

Your electric bill has two big parts: supply (the electricity itself) and delivery (the wires that bring it to you), plus taxes and fees. Data centers mostly threaten the supply side.

The grid operator for our region, PJM Interconnection, runs the power system for more than 67 million people across 13 states and D.C., including northern Illinois. Every year PJM holds a "capacity auction" — essentially paying power plants to promise they'll be ready when demand peaks a few years out. Those costs land in the supply portion of customer bills.

And those auctions have exploded. The auction for the 2024–2025 delivery year cleared at $28.92 per megawatt-day. Two cycles later, the December 2025 auction for 2027–2028 cleared at $333.44 — the maximum price federal regulators allow — for the third year running, totaling $16.4 billion. PJM's own independent market monitor attributed about 40% of that cost, $6.5 billion, to data center demand — and $6.2 billion of that was for data centers that haven't been built yet. A company can reserve a huge block of future power before pouring a foundation, and everyone on the grid helps pay for the reservation.

The second channel is transmission: new substations and high-voltage lines to serve giant loads. Traditionally those grid investments get spread across all customers — which is exactly what has regulators and utilities scrambling.

Data centers aren't the only new load hitting the grid — if you're weighing an EV, see what a home EV charger adds to your electric bill, with the per-mile math at current ComEd rates.

The Naperville wrinkle: your utility may not be ComEd

Here's the local twist: most of Naperville isn't served by ComEd at all. The City of Naperville runs its own municipal electric utility — in business for over 120 years, serving 60,000+ customers — and buys its wholesale power through the Illinois Municipal Electric Agency. A few outlying addresses with Naperville mailing addresses do fall in ComEd territory, so check whose name is on your bill.

Why it matters: wholesale capacity costs still flow through to a municipal utility that buys power in regional markets — but your rates are set by the city, not by state regulators, and the city's power-buying strategy is its own. ComEd's much-publicized customer protections, below, apply to ComEd customers specifically.

The guardrails Illinois has put up

This isn't going unchecked. Three verified developments:

• ComEd's transmission security agreements. Starting in January 2026, ComEd began signing 10-year take-or-pay contracts with big new power users — mostly data centers — requiring them to guarantee a decade of transmission payments, backed by letters of credit. The first batch covered eight customers and more than 6.5 gigawatts of planned load, shielding existing customers from over $2 billion in transmission costs over ten years. Federal regulators approved the first agreements in March 2026, and by September 2026 ComEd had six active agreements backed by more than $1 billion in letters of credit. The idea, in ComEd's words: customers who impose very large demands pay their fair share — if a data center uses less power than promised, or never gets built, the developer pays the difference, not you.
• The tax-break pause. Illinois' data-center incentive program — sales-tax exemptions for projects investing $250 million+ and creating 20+ jobs — drew 27 projects and an estimated $983 million in exemptions from 2020–2024. After a reform push failed in spring 2026, the governor directed the state to stop accepting new applications as of July 1, 2026. Existing deals keep their benefits; no new ones are being signed.
• Bill relief in the meantime. ComEd has pointed to over $800 million returning to customers as bill credits in early 2026 under the state's Climate and Equitable Jobs Act, plus a new income-based discount program.

None of this erases the underlying pressure — data centers are still coming, including a planned 1-gigawatt campus in Morris, roughly 50 miles southwest of Naperville. But the "who pays" question is being actively renegotiated in customers' favor.

What to actually watch on your own bill

• Know your provider. A City of Naperville electric bill and a ComEd bill have different line items and different protections. Start there.
• Watch the supply line. Capacity costs show up in supply charges, not delivery. If your supply rate climbs while delivery stays flat, wholesale markets are the reason.
• Compare year over year. The city publishes its municipal rates — look at the trend, not a single month.
• Efficiency still wins. Whatever the grid does, the cheapest kilowatt-hour is the one you don't use. (Our winterizing guide is the practical starting point as heating season approaches.)

Good to know