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EV · Pillar · Updated May 2026

Time-of-use EV plans: when they save and when they backfire.

Bruno de Madrazo
Bruno de Madrazo
Updated May 12, 2026·How we calculate this

Every EV-friendly utility page tells you to switch to a time-of-use plan. About 30 % of EV owners who do end up paying more than on the standard rate. Here is the math behind both outcomes — and the 4-step test to know which side of the line your household falls on.

TL;DR: TOU only wins if you can shift ≥ 70 % of your household kWh to off-peak. That's easy if you're a low-load EV-only household; very hard if you have central AC, electric resistance heat, a pool pump or you work from home. Always run the math on 12 months of your actual usage, not the utility's marketing example.

Anatomy of a TOU plan

The structure varies but most TOU plans break the day into three bands:

Band Typical hours Typical ¢/kWh
Peak4 PM–9 PM weekdays (summer); 5–9 PM weekdays (winter)$0.35–$0.55
Off-peak9 AM–4 PM weekdays, 9 PM–midnight$0.18–$0.28
Super-off-peakMidnight–6 AM, often plus midday weekends$0.04–$0.17

The savings opportunity is in the super-off-peak band — that's where Level 2 home charging belongs. The risk is the peak band, where running cooling/heating/cooking adds up fast.

When TOU works (4 scenarios)

  1. Low-load EV household. Single or couple, ~600 kWh/month, EV does 60 % of usage. Shifting that EV usage to super-off-peak slashes 40-60 % of the bill.
  2. Solar + EV pairing. Solar covers your daytime peak/off-peak baseline; the only meaningful kWh you import from the utility is overnight Level 2 charging at super-off-peak. Best-case economics.
  3. Heat pump + EV in NEM 3.0 California. Run the heat pump during super-off-peak (or solar production hours) and the EV at super-off-peak; the heat pump uses 4× less electricity than gas resistance heating at the same time. Compounds the TOU advantage.
  4. "Free nights" plans in Texas. Deregulated retail providers offering $0.00/kWh from 8 PM-6 AM. Even if the day rate is ~25 % higher than standard, the math works as long as ≥50 % of your usage is overnight.

When TOU backfires (5 scenarios)

  1. Summer AC during peak hours. Central AC in Phoenix runs 6-10 hours/day, much of it during the 4-9 PM peak window. The peak surcharge can be $400/season — eating most of the EV savings.
  2. Electric resistance heat (baseboard or whole-house). Heat can't be shifted to overnight. Peak heating hours match peak utility hours. Don't enroll in TOU until you switch to a heat pump.
  3. Work-from-home household. Cooking, laptops, lighting and HVAC running during the day = high off-peak and peak usage. The savings on EV charging get cancelled by the surcharge on everything else.
  4. Pool pump. Most pool pumps default to running 8 hours/day, often spanning peak hours. Reschedule to overnight before enrolling in TOU.
  5. Day-rate surcharge > EV savings. Some utilities (e.g. SCE TOU-D vs standard) charge ~$0.04/kWh more on peak hours than the standard rate would charge for the same kWh. If you can't shift enough load, you're paying more, not less.

The 4-step test to know your answer in 7 minutes

  1. Download 12 months of hourly kWh data from your utility (PG&E "Download My Data", Con Ed "Green Button", FPL "Energy Dashboard"). Most US utilities offer it as CSV.
  2. Bucket each hour into peak / off-peak / super-off-peak using the TOU plan's schedule. A simple spreadsheet pivot does it.
  3. Calculate "annual bill under each plan": sum(kWh × rate) for each band on the new plan; sum(kWh × $standard_rate) for the standard plan.
  4. Add your projected EV charging entirely in super-off-peak (assuming you'll use Level 2 scheduling). Compare totals.

If TOU wins by <5 %, the gains are within noise and not worth the rate-change hassle. If it wins by >10 %, switch immediately. Most utilities let you switch back once per 12 months without penalty.

Level 2 home charging: scheduling matters more than the plan

If your Level 2 charger has scheduling built in (most do — Tesla Wall Connector, Wallbox Pulsar Plus, ChargePoint Home Flex, Emporia EV), the savings come automatically. If it doesn't, every modern EV (Model 3/Y/3-Performance, Mach-E, Ioniq 5/6, Bolt, F-150 Lightning) has scheduling in the dashboard. Set the start time to 30 minutes after super-off-peak begins (gives the utility a buffer for slightly off-clock meters) and the stop time as 30 minutes before super-off-peak ends.

Worked example · reproduce it in the calculator

Model Y, 12,500 mi/yr: flat rate vs TOU super-off-peak

Inputs: a Tesla Model Y at ~3.5 mi/kWh covers 12,500 mi/yr ≈ 3,570 kWh/yr ≈ 300 kWh/month of home charging. Flat rate is the 2026 US average of $0.18/kWh. On TOU, all charging is scheduled overnight in the super-off-peak band — we use $0.08/kWh, mid-range of the $0.04–$0.17 band shown above.

Flat rate — 300 kWh × $0.18$54.00 / month
TOU super-off-peak — 300 kWh × $0.08$24.00 / month
Saved on EV charging — 300 kWh × ($0.18 − $0.08)$30.00 / month
EV-charging savings: $30/month = $360/year — squarely inside the $300–$900/yr range a TOU-aware utility typically delivers. But that's only the charging line. The catch: TOU re-prices every other kWh in the house too. If your peak-hour load can't move (next section), the surcharge on the rest of the home can wipe this $360 out.

Different car, mileage or off-peak rate? Override the home rate in the EV charging calculator to model both plans side by side and get your own number.

The verdict: switch or stay on flat rate?

TOU is not a free win — it re-prices your whole bill, not just the EV. Use the $30/month EV-charging gain above as your budget: if your un-shiftable peak load costs more than that in surcharge, you lose. Here's the clean split.

Switch to a TOU plan if…

  • You can shift ≥ 70 % of household kWh off-peak — an EV-only or low-load home, ~600 kWh/month.
  • Your EV charging alone is 250–350 kWh/month, banked at super-off-peak ($0.04–$0.17) — that's the $360/yr above.
  • You have solar, or a heat pump you can run during super-off-peak / solar hours.
  • A Texas "free nights" plan covers ≥ 50 % of your usage overnight.

Stay on flat rate if…

  • Central AC runs through the 4–9 PM peak. A ~$400/season summer peak surcharge dwarfs the $360/yr EV win.
  • You have electric resistance heat that can't be shifted off the peak window.
  • You work from home — daytime cooking, HVAC and devices push load into peak/off-peak hours.
  • Your peak premium is high: even +$0.04/kWh on ~400 un-shiftable peak kWh/month ≈ $16/month, over half the EV gain — and most homes can't move that little.

Rule of thumb: TOU pays only when the kWh you can't move out of peak cost you less in surcharge than the kWh you can move to super-off-peak save you. Run the 4-step test above on 12 months of your real data before enrolling.

Frequently asked questions

What is a time-of-use (TOU) electricity plan?

A residential rate where the price per kWh varies by time of day. Typical: high peak ($0.30-0.55/kWh, 4-9 PM), medium off-peak ($0.15-0.25/kWh), low super-off-peak ($0.04-0.17/kWh overnight). Designed to incentivize moving usage off-peak.

When does TOU save EV owners money?

When ≥70-80% of total household kWh shifts to off-peak, and the savings on EV charging exceed any peak surcharge on the rest of the home. Typically saves $300-900/yr for a Model Y on 12,500 mi/yr.

When does TOU backfire on EV owners?

(1) AC-heavy summer cooling on peak, (2) electric resistance heat, (3) work-from-home with high daytime usage, (4) pool pump scheduled during peak, (5) utility's day-rate surcharge exceeds the EV-charging savings.

Sources: PG&E, SCE, SDG&E, Con Edison, Eversource, Duke Energy, TXU, Reliant rate cards (Q1 2026), EPA fueleconomy.gov for EV efficiency, EIA national price index May 2026. Last reviewed May 12, 2026.