Illinois Hourly Pricing, With or Without a Battery
ComEd Hourly Pricing and Ameren Power Smart Pricing bill the actual wholesale price, which changes every hour and is published the afternoon before, on June 29, 2026 ComEd ran about 2¢/kWh overnight and passed 60¢ between 7 and 8 p.m., roughly a 30× swing. That's worth reacting to whether or not you have a battery: an EV charger or a battery captures the most of it, but pre-cooling alone captures savings too. Hungry Machines reads tomorrow's published curve, times the cheap hours against your devices, and now also watches for the real-time spikes the forecast sometimes misses.
Who this is for
- ComEd customers enrolled in, or considering, Hourly Pricing in Chicago, Cook County or the rest of northern Illinois
- Ameren customers enrolled in, or considering, Power Smart Pricing in central or southern Illinois
- Households with a home battery, EV charger or central AC they want dispatched against the live price curve, not a fixed timer
- ComEd customers also on Delivery Time-of-Day or enrolled in Peak Time Savings, stacking on top of Hourly Pricing
Not for you if you're on the standard fixed supply rate with no flexible load to move, there's no curve yet to react to, and no automation changes a flat price.
What Hungry Machines does in this situation
In your account settings you pick Dynamic pricing and your region, ComEd or Ameren, plus a delivery-charge estimate, and ComEd customers can layer on Delivery Time-of-Day's four period prices if they've enrolled. For a battery, you set the target charge, the minimum you'll accept, and a deadline; HVAC and water heater get their own comfort limits the same way.
Each night, Hungry Machines pulls the next day's published hourly prices, tomorrow's forecast, and a thermal model of your home, then builds a 24-hour schedule: the battery and EV charge in the genuine overnight trough, HVAC pre-cools just enough to skate past the expensive stretch, and the water heater times itself to the day's cheapest energy. It does this again tomorrow against tomorrow's new prices, because the cheap hour moves.
You see the plan and its reasoning before it runs, and today's estimated savings against a flat baseline. Override any slot, or pause one appliance's optimization without touching the rest.
The arithmetic
- ComEd, June 29, 2026. about 2¢/kWh overnight to over 60¢/kWh between 7 and 8 p.m., roughly a 30× swing in a single day.
- Day-ahead vs. real-time. across 84 summer days, the median gap between ComEd's published forecast and the billed real-time price was 0.7¢/kWh. On July 3, 2026, the forecast priced 5 p.m. at about 25¢/kWh; the billed real-time price that hour was about 120¢/kWh.
- Both utilities. the shape is the same on ComEd's PJM market and Ameren's MISO market: demand-driven troughs overnight, an air-conditioning-driven peak in late afternoon, and a curve that's different tomorrow than it was today.
These are published wholesale prices and the measured gap between ComEd's forecast and its billed price, not measured results from Hungry Machines customers. Your own saving depends on how much load you can move and how steep a given day's curve turns out to be.
How to set it up
If you already run Home Assistant, the Home Assistant integration reads your battery, EV charger and climate entities directly, install via HACS, sign in, and pick Dynamic pricing plus your region in Settings. No Home Assistant instance yet? The Home Hub runs the same dynamic-pricing optimizer on its own hardware, coordinating everything from one box. Either route runs the free tier on one device with no payment method required; see pricing for what Premium adds.
Read the full guides
- ComEd Hourly Pricing: Turning Daily Wholesale Rates Into Savings
- We Measured a Summer of ComEd's Day-Ahead Prices Against the Real-Time Prices You're Billed
- Ameren Power Smart Pricing: Turning Hourly Rates Into Savings
- ComEd Peak Time Savings: A Free Bill Credit for Cutting Load on Hot Days
- ComEd Delivery Time-of-Day: A Variable Delivery Charge That Stacks With Hourly Pricing
Frequently asked questions
Is ComEd Hourly Pricing or Ameren Power Smart Pricing risky?
Your price follows the wholesale market, so a rare spike costs more in that hour, on June 29, 2026, ComEd ran near 2¢/kWh overnight and passed 60¢ between 7 and 8 p.m., a roughly 30x swing in one day. The exposure is smaller than that number suggests, for two reasons: spikes concentrate in a handful of summer evening hours, and you collect every cheap hour in between, which is most of them. Ameren's Power Smart Pricing has run on the same mechanism since 2007, which is one reason to treat it as a mature program rather than an experiment. The honest caveat: on a fixed rate you can't lose to a spike, and a household with no flexible load and no automation has little to gain from either program.
Does ComEd bill the day-ahead price I planned against, or something else?
The real-time price, the average of that hour's twelve 5-minute market prices, not the day-ahead forecast published the afternoon before. Across 84 summer days in 2026 the two were close most of the time, a median gap of 0.7¢/kWh, but the forecast underpriced the worst hours: of 92 hours that settled at 14¢/kWh or more, it had priced almost half of them below that line. The single biggest miss was July 3, 2026, when the day-ahead forecast had 5 p.m. at about 25¢/kWh and the real-time price that hour billed at about 120¢. Planning on the forecast is still the right default, it ranked cheap and expensive hours well on 76 of the 84 days, but it's not a guarantee on the handful of days it misses.
Do I need a battery or EV to benefit from hourly pricing?
No, though they help the most, because they're large loads that do not care when they run. Moving a 40 kWh EV charge or a battery's overnight charge from a 60¢ hour to a 2¢ hour is the largest single saving on the rate. Pre-cooling a home with central AC captures savings on its own, with no hardware purchase required, your house is already a thermal battery, and cooling it while power is cheap lets it coast through the expensive hours. A water heater does the same trick with hot water. What actually decides the benefit is how much of your consumption is time-flexible, not which specific appliance is in the garage or the utility closet.
About Hungry Machines
Outsmart your electric bill - Hungry Machines Energy provides an energy management system that shifts HVAC, EV charging, home batteries, and other electric loads to cheaper hours for homes and buildings with solar power or variable electricity rates.