How Time-of-Use Electricity Rates Change Your Power Bill

Running the dishwasher at 8 p.m. can cost more than running it at 10 p.m., even if it uses exactly the same electricity. That is the basic idea behind time-of-use rates: your utility changes the price of power according to when you use it.

The tricky part is that “peak” does not mean the same hour everywhere, and a cheaper energy rate does not automatically make the whole bill cheaper. The schedule, charges, and your household’s habits all matter.

What time-of-use rates mean

With a flat-rate plan, each kilowatt-hour (kWh), a measure of electricity use, has roughly the same energy price throughout the day. A time-of-use (TOU) plan divides the day into periods, commonly peak, off-peak, and sometimes mid-peak. The utility charges a different rate in each period.

Peak periods often fall in late afternoon or evening, when people return home and demand rises. Off-peak periods may include overnight hours. But the exact windows depend on the utility, season, and plan. Some utilities also set a super-off-peak period during sunny hours, when solar generation is abundant.

TOU pricing generally requires a meter that records when electricity is used, not just the total amount. Many digital meters can do this, though customers may need to opt into a TOU plan. The meter measures consumption; it does not decide which appliances to blame. Fortunately, it does not have opinions about laundry.

Why utilities charge different prices

Electricity supply has to match demand continuously. When demand climbs, the grid may need more expensive generators, imports, or other resources. Moving flexible use to quieter hours can reduce pressure during the most expensive periods.

The price signal can also reflect generation patterns. Solar panels produce most during daylight, so a region with substantial solar may have low midday wholesale prices and a sharper evening peak after solar output falls. That mismatch is one reason grids use batteries to move electricity between hours. Greadly's explanation of why four-hour batteries can compete with gas peakers covers one way the grid responds to that timing problem.

Fact: The U.S. Energy Information Administration reported an average residential electricity price of 16.48 cents per kWh in 2024. That is a national average, not a TOU rate or a promise about any particular utility’s prices. Local tariffs can differ substantially, and the price shown on a bill may combine energy, delivery, taxes, and fixed charges.

A worked example with real arithmetic

Consider a household that uses 900 kWh in a month. For a simple comparison, assume its flat energy rate is 16 cents per kWh. The energy portion costs 900 × $0.16, or $144.

Now assume a TOU plan charges 30 cents per kWh during peak hours and 10 cents off-peak. These are illustrative rates, not a real utility tariff. If the household uses 300 kWh at peak and 600 off-peak, its energy charge is (300 × $0.30) + (600 × $0.10), or $150. With the same total use, that is $6 more than the flat-rate example.

If the household shifts 100 kWh from peak to off-peak, the calculation becomes (200 × $0.30) + (700 × $0.10), or $130. The shift saves $20 on the energy charge compared with its original TOU pattern. It does not necessarily save $14 compared with the flat-rate plan: the plans could have different monthly fees, delivery charges, or seasonal terms. The example isolates the energy price to show the arithmetic, not to forecast a bill.

What can realistically be shifted

Flexible loads are the easiest candidates: laundry, dishwashing, electric-vehicle charging, and some water heating. A programmable appliance or charger can run overnight or during a designated low-price window without requiring anyone to stay awake and supervise the washing machine.

Heating and cooling are more complicated. Pre-cooling a home before a peak period may help, but it depends on the building, the weather, and the thermostat settings. The same approach can be uncomfortable or ineffective in a poorly insulated home. Greadly's guide to lowering cooling costs during a heatwave looks at measures that affect the amount of electricity used, not just the hour it is used.

Some loads are hard to move. Cooking dinner, caring for an infant, or charging a medical device is not always negotiable. A rate plan should fit the household rather than turn ordinary routines into a dispatch center.

Interpretation: a lower price is not the same as lower use

TOU rates reward timing, but they do not guarantee savings. A household that uses a lot of electricity during peak hours can pay more than it would on a flat plan. A household that shifts use may lower its energy charge, but fixed monthly fees still apply and can dilute the reduction.

There can also be a rebound effect: a low overnight rate may encourage someone to charge a car or run equipment longer than needed. The meter sees the extra kWh, not the good intentions behind them. Compare plans using your own hourly or interval usage data where available, and check the full tariff rather than comparing one headline rate.

Prediction: more schedules, not one universal peak

Prediction: As solar generation, batteries, electric vehicles, and air-conditioning loads change local demand, utilities are likely to keep adjusting the hours that are cheapest and most expensive. Some plans may make midday electricity cheaper; others may focus on summer evenings or use different schedules in different seasons.

Interpretation: That makes the label “off-peak” less useful than the actual clock times and prices on a particular tariff. A schedule designed for one region may not suit another, even if both utilities use the same name for their plans. Treat published rate windows as local rules, not universal facts.

How to check whether a plan fits

Find the current tariff and note its peak hours, seasonal changes, energy rates, monthly fees, and any minimum bill. Then review a few months of usage, especially the hours when large appliances or cooling systems run. If the utility offers a bill comparison using your historical data, it can provide a more grounded estimate than a generic calculator.

Finally, ask what happens if the plan is a poor fit: some utilities allow customers to switch back, while others set limits or apply a transition period. Time-of-use pricing is a tool for matching consumption to the grid’s daily rhythm. Its value depends on whether that rhythm has room in your household’s schedule.