If your utility bills you the same rate whether you charge at 5pm or 5am, none of this applies to you. But an increasing number of utilities — and in some states, all new residential customers by default — now charge different prices depending on the hour. On those plans, when you charge often matters more than which charger you bought.
Key Numbers
- SDG&E’s EV-TOU-5 plan (effective August 2026) charges 13.1¢/kWh in its super-off-peak window versus 80.2¢/kWh during the 4–9pm on-peak window — roughly a 6x difference for identical electricity.
- Southern California Edison customers face peak rates up to 71¢/kWh versus off-peak around 36¢/kWh — close to a 2x spread.
- Xcel Energy’s Colorado TOU plan (effective October 2025) prices peak hours (5–9pm weekdays) at 2.7x the off-peak rate, and TOU is now the default rate structure there.
- PECO in Pennsylvania publishes $0.32/kWh on-peak versus as low as $0.053/kWh in its deepest off-peak window.
- Over 75% of U.S. electricity meters are now smart meters, which is what makes hour-by-hour TOU billing practical at scale.
- California mandated TOU as the default rate structure for new residential customers starting in 2024 — meaning “check if you’re on a flat rate” is no longer a safe assumption there.
Short Answer
If your utility offers a time-of-use plan, shifting EV charging to the cheapest window can cut your charging cost by half to six times less, depending on the utility — the spread is real and it’s specific to your provider, not a national constant. The mechanism is genuinely a car’s dashboard-and-app setting or the charger’s own scheduling feature, not extra hardware. Whether it’s worth switching plans at all depends on how much of your total household usage, not just EV charging, you can reliably shift out of the peak window.
Why Utilities Price Electricity by the Hour
Grid demand isn’t flat through the day. Late afternoon into evening — when people get home, turn on AC or heat, cook dinner, and plug in the car — is typically the highest-demand window, and meeting that spike sometimes requires firing up expensive “peaker” plants that only run during high-demand hours. In states with heavy solar adoption, there’s an added wrinkle known as the “duck curve”: solar makes midday power abundant and cheap, then evening demand hits right as solar output drops off, creating a sharp price swing utilities want to smooth out by giving customers a reason to shift usage. TOU pricing is the price signal utilities use to spread that load — cheap when the grid has spare capacity, expensive when it’s under strain.
What the Gap Actually Looks Like, By Utility
| Utility | Off-peak rate | On-peak rate | Ratio |
|---|---|---|---|
| SDG&E (EV-TOU-5, Aug 2026) | 13.1¢/kWh (super off-peak) | 80.2¢/kWh | ~6.1x |
| Xcel Energy Colorado (Oct 2025 plan) | — | — | 2.7x |
| Southern California Edison | ~36¢/kWh | ~71¢/kWh | ~2.0x |
| PECO (Pennsylvania) | $0.053–0.076/kWh | $0.32/kWh | ~4.2–6.0x |
Rates and windows change through utility rate filings, sometimes more than once a year — SDG&E’s own EV-TOU-5 schedule shifted between April and August 2026 alone. Always confirm current numbers on your utility’s own rate page before making a decision, rather than relying on any article, including this one, as the live figure.
Our Own Worked Example, Applied to Three Real Rate Schedules
To make this concrete, we ran the same standardized usage assumption — a 40-amp Level 2 charger drawing roughly 7.7 kW, charging about 9 hours a week, for a rough annual total of 3,600 kWh — against three utilities’ actual published rates, to see what the peak-vs-off-peak gap is worth in dollars rather than just percentages.
| Utility | All off-peak (3,600 kWh/yr) | All on-peak (3,600 kWh/yr) | Annual gap |
|---|---|---|---|
| SDG&E EV-TOU-5 | 3,600 × $0.131 = $472 | 3,600 × $0.802 = $2,887 | ~$2,415 |
| Southern California Edison | 3,600 × $0.36 = $1,296 | 3,600 × $0.71 = $2,556 | ~$1,260 |
| PECO | 3,600 × $0.076 = $274 | 3,600 × $0.32 = $1,152 | ~$878 |
These are our own calculations, run independently against each utility’s published rate — not copied from a single source’s conclusion. The pattern holds across all three: the annual swing between “always charge at peak” and “always charge off-peak” runs well into four figures at this usage level, even though the underlying rate structures and window definitions are completely different state to state.
See Your Own Number
How to Actually Shift Your Charging
- Use your car’s built-in charge schedule — nearly every EV lets you set a charging window in the app or touchscreen; this is the simplest method and needs no extra hardware.
- Use your Level 2 charger’s own scheduling feature if it has one — useful if you want scheduling to persist regardless of which vehicle is plugged in, for a household with more than one EV.
- Check whether your utility has an EV-specific TOU plan separate from its general TOU plan — these sometimes have a deeper super-off-peak window built specifically around overnight charging, as with SDG&E’s EV-TOU-5.
- Confirm you’re not accidentally on the general TOU plan when an EV-specific one exists — the rate structures and windows can differ meaningfully between the two, as PG&E’s own EV2-A versus general E-TOU-C comparison shows.
When TOU Charging Isn’t a Clear Win
- If you can’t reliably charge only off-peak — irregular schedules, unpredictable trips, or needing a top-up mid-day — some of your charging inevitably falls at the more expensive rate, cutting into the savings shown above.
- If switching to TOU raises your rate on everything else you use at peak hours — cooking, AC, laundry — the EV savings can be partly offset by higher costs on the rest of your household’s peak-hour usage, depending on your overall consumption pattern.
- If you’re on a low-usage flat rate that’s already cheap — worth running the actual comparison for your specific household rather than assuming TOU is automatically better, since some flat-rate plans remain competitive for lower-usage homes.
This ties directly into sizing your home charging setup in the first place — our home charger sizing guide covers how charging window length interacts with breaker size, which matters more once you’re deliberately charging in a narrow off-peak window rather than whenever convenient.
FAQ
Do I need a smart charger to take advantage of TOU rates?
No — most EVs can schedule charging directly from the car’s own app or touchscreen without any special charger hardware. A smart/scheduling-capable charger is a convenience, not a requirement.
Is TOU charging worth it if I only drive a short daily commute?
Possibly less so in absolute dollars, since your total annual kWh is lower, but the percentage savings still apply — run your own numbers through the calculator above with your realistic annual kWh.
Can my utility force me onto a TOU plan?
In some states, yes for new customers by default — California mandated this for new residential customers starting in 2024. Existing customers and other states vary; check your utility’s own enrollment policy rather than assuming.
Why do TOU windows differ so much between utilities?
Peak timing reflects each grid’s own local demand pattern and generation mix — solar-heavy grids tend to have a sharper evening peak (the “duck curve”), while others peak differently. There’s no single national TOU schedule.
Does charging off-peak also help the grid, not just my bill?
Off-peak hours generally coincide with lower overall grid strain and, in many regions, with wind or solar generation being more available — so shifting demand off-peak can reduce the need for peaker plants, though the exact environmental benefit depends on your local grid’s generation mix.
The Short Version
Time-of-use electricity rates turn “when you charge” into a real financial decision, not a minor convenience. The gap between peak and off-peak rates varies enormously by utility — anywhere from roughly 2x to 6x in the examples here — which means the national headline number matters far less than your own utility’s actual published rates. The mechanism to capture the savings already exists in your car’s app; the real question is how much of your charging (and household usage generally) you can reliably shift, and whether an EV-specific TOU plan exists and beats your utility’s general one. Check your own current rate schedule directly with your utility before switching plans, since these numbers change through rate filings more often than most people expect.
About the author: Written by Shurah, who researches and writes independently on the real cost of EV ownership — charging, maintenance, and total cost of ownership — backed by primary data and original calculations rather than recycled lists.
