Real-Time Electricity Pricing (RTP) for Homes: kWh, Hourly Rates, and Load Shifts That Matter

Most bill tutorials assume a single effective rate: multiply kWh by one number, add a fixed charge, and you are done. Real-time (or closely related hourly) retail products break that story on purpose: the supply side of the bill can follow wholesale or index-style conditions over the day, so when you use energy becomes part of the price—not just how many kWh you used.

WattSizing’s job is not to sell you a tariff with a name and a color graphic. It is to give you kWh and watt logic you can use if you are shopping programs or already enrolled.

If you are still learning the relationship between your meter’s kWh and the invoice, read How to calculate electricity bill from kWh first, then return here for time-varying structures.

Tools: WattSizing Calculator for load lists; How to reduce electricity bill in the United States for a broader, non-RTP view of U.S. bill mechanics.

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1) What this article calls “RTP” (a practical definition)

Strict “real time” in energy markets can mean “price determined close to the moment of use,” sometimes tied to a regional wholesale market. What you see as a customer can still differ:

• The utility may use PJM real-time (or a similar) hourly pattern for supply charges, then add distribution, riders, and policy lines the way the tariff says.
• Some programs set day-ahead hourly prices the night before (useful for planning) rather than a pure five-minute world.

Because naming varies, treat “RTP” in marketing as a label you verify against your tariff PDF: What hour marks count? What line items are included in the “energy” you are trying to time-shift? Is there a capacity demand charge, monthly minimum, or pass-through for distribution that weakens the benefit of small shifts?

A neutral policy overview of one state’s “Utility Real Time Pricing” concept for Illinois residents, including a comparison of ComEd (real time hourly through the day) and day-ahead hourly styles for a different large Illinois provider, is published by the state’s public guidance site: Illinois: Utility Real Time Pricing. Use it as a structural example of how “two big utilities, two clock philosophies” can coexist in one state—not as your personal bill guarantee.

If you are outside Illinois, do not import their numbers to your home; import the questions: clock definition, which charges move hourly, and which charges are “there no matter what you do at noon.”

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2) The kWh math in one honest paragraph

For any hour h where a supply-related rate is P(h) in dollars per kWh, and you consume kWh(h) in that same hour, the variable portion contributed by that piece is a sum across hours, not a single product:

• Variable energy ≈ Σ kWh(h) × P(h) + (other lines the tariff says)

Why that matters to WattSizing readers

• Shifting 1 kWh from an expensive hour to a cheap hour saves about (P(expensive) − P(cheap)) for that kWh on the time-varying part—if your home can actually move the load, and if the rest of the bill does not cap your upside.

• If a large share of the bill is fixed monthly or a volumetric minimum, tiny shifts still help only the moving slice.

This is a different headspace than a flat rate. If you are still thinking in a single $/kWh, convert your thinking one step: a week of hourly kWh and a week of effective hourly all-in “energy you care to shift” (from your own statements once enrolled).

For baseline appliance watt ranges before you time-shift, our library of how many watts does a … use articles is a useful cross-check—dishwasher, dryer, and cooking loads are common “move candidates.”

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3) What kinds of home loads are worth moving in principle

Good candidates (often)

• EV charging when you can schedule it, subject to your charger and home wiring—see How many watts does an EV charger use? for power magnitudes
• Dishwasher / laundry if delay timers align with the hours you are trying to target
• Storage water heating if you can heat in cheap hours without hurting comfort
• Pool pumps in climates where a schedule change is safe and allowed

Frequently overestimated

• “Unplugging the router” in a high-price hour while leaving 1.5 kW of resistive heat on—your router is not the driver.
• AC comfort in a heat wave: you may choose a higher setpoint, but the human limits are real. Treat cooling shifts as a comfort trade, not a spreadsheet fantasy.

Still hard to time-shift in practice

• Television and desktop gaming that track human schedules more than the wholesale clock
• Refrigeration and many always-on devices—small in hourly timing leverage unless your tariff has extreme spreads

To judge cycle-dependent loads, cross-read How to estimate appliance duty cycle.

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4) A two-week self-audit (no new gadgets required)

1. If you are already on a time-varying product, print interval data (hourly) for 14 days that include a weekday block and a weekend.
2. Tag your top three kWh contributors by hour: EV, HVAC, water heat, and cooking are usual suspects; your data will name yours.
3. Re-run a simulated schedule in a spreadsheet: move only loads you would move in real life.
4. If the model shows tiny savings, your house may be inelastic to hourly prices without hardware changes—or your tariff’s “movable” slice is small.

Why two weeks? A single spiky day makes dramatic stories; billing is about patterns.

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5) Where RTP fits next to time-of-use (TOU) and plain tiered rates

Idea	You think about…	Best when…
Flat volumetric	One effective $/kWh	You like simplicity and cannot shift much load
TOU (peak/off-peak)	A few rate bands + clock windows	You can run large loads in clearly cheaper bands
Hourly / RTP-style	Many hours with different $/kWh	You will track price signals and you can move load safely

None of these replace the physics: W × hours = Wh, and Wh/1000 = kWh. The tariff only prices those kWh.

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6) A conservative external reference set (U.S. readers)

• Illinois structure comparison (two major Illinois approaches): plugin.illinois.gov — Utility Real Time Pricing — public guidance page describing real-time vs day-ahead program shapes at a high level.
• PJM + customer education (example utility interface): ComEd’s hourly materials show how some utilities surface hourly market pricing to customers for programs built around it—use as a pattern, not a promise that your state copies the same rules.

WattSizing does not archive third-party live price tables in this article; those numbers go stale the same week they are published. Use your own utility’s current tariff PDF for anything involving money.

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FAQs

Is RTP always cheaper?

No. It can be cheaper for households that can avoid a few very expensive hours or shift large loads, and more expensive for households whose usage is stuck in expensive hours (cooling load in late afternoon) or that dislike tracking signals.

Do I need a smart meter for hourly billing?

Usually yes for any credible hourly true-up; verify with your program’s terms (sometimes legacy metering is not eligible).

Can solar + RTP be combined intelligently?

Sometimes exports and import rates interact in nontrivial ways depending on NEM or successor tariffs in your state; treat “I export at noon, buy at 8 p.m.” as a full tariff question, not a slogan. If you are hybrid or backup-curious, start with Off-grid vs grid-tied vs hybrid solar.

Is shifting the same as “saving a planet”?

Energy shifting can help local network peaks; your bill savings are the part you can bank. Keep claims proportional.

I rent. Is RTP even my decision?

Often no; tenant meter accounts and landlord equipment (water heat, mini-splits) may block changes. The math still helps you choose among offers if you pay the bill directly in competitive retail markets with eligible meters.

Why does WattSizing keep repeating “kWh, not slogans”?

Because a rate name does not run your dishwasher; kWh in an hour does, priced by that hour under an hourly product.