Quick Answer
Time-of-use EV charging reduces the bill when most charging happens during off-peak hours. Drivers who can keep charging inside the overnight window generally see cleaner savings than drivers who regularly plug in during high-demand evening periods.
A TOU plan is not a guaranteed discount. The EV side can improve while the rest of the home gets more expensive during peak hours. Run the EV math first, then check the whole bill.
Monthly savings = EV kWh per month x (standard rate - off-peak rate)Treat that formula as a screening tool. An actual utility bill may also include seasonal schedules, weekday and weekend windows, customer charges, supply charges, second-meter costs, or managed-charging rules.
What Time-of-Use Electricity Rates Actually Mean
Time-of-use rates are utility plans that change the electricity price by hour or period. Utilities use them because electricity demand is not flat. EIA describes off-peak periods as lower-demand periods, and those periods differ by utility.
Why TOU Rates Matter for EV Owners
EV charging is one of the largest flexible electric loads in a typical household. Refrigerators, routers, and medical devices have limited scheduling flexibility. An EV often has more room to wait until the low-cost window opens.
DOE managed-charging guidance describes scheduling charging sessions around utility TOU periods to reduce operating costs. AFDC consumer guidance also notes that many EV owners charge at home, which is why home TOU savings matter most for drivers who do most of their charging at their residence.
If you mostly charge at work or at public DC fast chargers, home TOU rates will have less effect on your total vehicle energy spend.
The Basic Formula for TOU EV Charging Savings
The calculation starts with monthly miles, converts those miles into wall energy, then applies the rate difference.
Monthly EV kWh = Monthly miles driven / Miles per kWh / Charging efficiency
Monthly charging cost = Monthly EV kWh x Electricity rate per kWh
Monthly savings = Monthly EV kWh x (standard rate - off-peak rate)For planning, a 90% charging-efficiency assumption is a reasonable AC charging estimate. The exact number can vary by charger, vehicle, temperature, and session behavior.
Step-by-Step Example
Use these assumptions:
| Step | Calculation | Result |
|---|---|---|
| Energy used by the car | 1,000 / 3.5 | 285.7 kWh |
| Energy pulled from the wall | 285.7 / 0.90 | 317.4 kWh |
| Standard charging cost | 317.4 x $0.18 | $57.13 |
| Off-peak charging cost | 317.4 x $0.11 | $34.91 |
| Monthly savings | $57.13 - $34.91 | $22.22 |
| Annual savings | $22.22 x 12 | $266.64 |
This driver saves a little over $22 per month by moving charging from a flat $0.18 rate to an $0.11 off-peak rate. The savings only hold if most charging actually stays inside the cheap window.
TOU Savings by Monthly Mileage
The table below uses 3.5 miles/kWh, 90% charging efficiency, a $0.18/kWh standard rate, and a $0.11/kWh off-peak rate.
| Monthly miles | Estimated wall kWh | Standard cost | Off-peak cost | Monthly savings | Annual savings |
|---|---|---|---|---|---|
| 500 | 158.7 | $28.57 | $17.46 | $11.11 | $133.33 |
| 1,000 | 317.5 | $57.14 | $34.92 | $22.22 | $266.67 |
| 1,500 | 476.2 | $85.71 | $52.38 | $33.33 | $400.00 |
| 2,000 | 634.9 | $114.29 | $69.84 | $44.44 | $533.33 |
TOU Savings by Rate Difference
Now hold monthly wall energy at 317 kWh and the standard rate at $0.18/kWh. The size of the off-peak discount drives the result.
| Off-peak rate | Monthly charging cost | Monthly savings vs. standard | Annual savings |
|---|---|---|---|
| $0.08/kWh | $25.36 | $31.70 | $380.40 |
| $0.10/kWh | $31.70 | $25.36 | $304.32 |
| $0.12/kWh | $38.04 | $19.02 | $228.24 |
| $0.14/kWh | $44.38 | $12.68 | $152.16 |
| $0.16/kWh | $50.72 | $6.34 | $76.08 |
A large gap between the standard rate and the off-peak EV charging rate can produce noticeable savings. A small gap may not justify changing the household schedule.
When Time-of-Use Charging Saves the Most
TOU savings are strongest when the off-peak discount is meaningful, monthly charging volume is high, and the household can reliably shift charging into the cheap window.
Hardware affects whether the schedule holds. A Level 2 charger can finish more of the session inside the off-peak period. The bill still depends on kWh and rate, but faster charging can keep more of those kWh in the right time bucket.
When a TOU Plan May Not Save Money
TOU may not help when the off-peak discount is small, peak rates are very high, the home uses a lot of electricity during the evening peak, or most actual charging happens away from home.
| Bill impact | Monthly amount |
|---|---|
| EV savings from off-peak charging | $20 |
| Extra peak-hour household cost from HVAC, cooking, and laundry | $25 |
| Net household result | $5 worse off |
That is why whole-home TOU plans need more than EV math. If the plan applies to the full home, compare the total bill, not just the car.
Best Time to Charge an EV
Start with the utility's off-peak window, often overnight. "Overnight" is still not a complete answer. Some plans include a super-off-peak period, some use a long off-peak block, and some add summer peak or super-peak pricing in the afternoon.
| Utility example | Structure | What it shows |
|---|---|---|
| PG&E | Whole-home EV2-A and separately metered EV-B options | One utility can offer multiple EV rate paths with different billing structures. |
| Con Edison | Whole-home TOU and EV-only second meter options | EV-specific rates can isolate charging, but added meter charges may apply. |
| Duke Energy | Territory-specific TOU or managed-charging programs | Some utilities use credits and managed charging instead of one standard EV tariff. |
The decision is local: check your actual rate schedule, then set the vehicle or charger to that window.
How to Schedule EV Charging
Start with the controls you already have: the vehicle app, the charger app, or a smart charger schedule. If your utility offers managed charging, review the enrollment rules before joining.
- Set the charging start time well inside the off-peak window.
- Leave a buffer before the off-peak window closes.
- Check the first few sessions in the vehicle or charger log.
- Keep a manual override for days when you need peak-hour charging.
Check the logs after the first few sessions. A failed schedule can quietly move charging into peak hours.
Level 1 vs. Level 2 on TOU Plans
Level 2 can work better on TOU plans because it delivers more energy during a shorter cheap window.
| Charging setup | 8-hour off-peak window | Energy before losses |
|---|---|---|
| Level 1 at 1.4 kW | 1.4 x 8 | 11.2 kWh |
| Level 2 at 7.2 kW | 7.2 x 8 | 57.6 kWh |
Low-mileage drivers may still be fine on Level 1. A full EV with a longer commute may need Level 2 to finish inside the off-peak window. For a broader comparison, see the Level 1 vs. Level 2 charging guide.
Public Charging, Renters, and Apartment Residents
TOU savings primarily belong to home charging. Public charging networks use their own pricing structures, including session, time, membership, or energy-based pricing. AFDC consumer guidance says drivers should normally expect public charging, especially DC fast charging, to cost more than home electricity.
Renters and apartment residents still have options, but the first question is access. Multifamily charging can involve parking, electrical service, billing, and legal constraints. In some buildings, the better first step is a dedicated outlet, shared charger, workplace charging routine, or EV-only metering path.
Common Mistakes With TOU EV Charging
How to Decide If a TOU Plan Is Worth It
Before switching, answer these questions with your own utility bill and rate sheet.
Before You Switch Plans
The goal is not to fill out a worksheet. The goal is to avoid choosing a cheaper EV charging window that raises the rest of the household bill. Check these items before moving to a TOU plan.
| What to check | Why it matters |
|---|---|
| Monthly EV kWh | This tells you how much energy is actually available for TOU savings. |
| Off-peak rate vs. current rate | A small discount may not be worth schedule changes or fixed fees. |
| Peak rate and peak hours | High evening prices can offset the EV savings through HVAC, cooking, laundry, or water heating. |
| Charging window length | A short off-peak window may require Level 2 charging to finish before peak pricing starts. |
| Fixed fees or second-meter costs | EV-only rates can look attractive until added monthly charges are included. |
| One full billing cycle | Projected savings should be checked against the first real bill before treating the plan as a win. |
For a faster estimate, use the CostToCharge.com EV Charging Cost Calculator, then compare the baseline result with your utility's TOU windows. The existing home charging cost by time-of-use plan guide gives a second framework for blended-rate checks.
Conclusion
TOU electricity rates reduce EV charging cost only when charging behavior matches the plan. The savings depend on the off-peak discount, miles driven, vehicle efficiency, charging losses, and whether the rest of the household can avoid expensive peak periods.
Before switching, compare your current bill structure with the utility's TOU tariff. Estimate your wall kWh, schedule charging inside the cheap window, and verify the result over at least one full billing cycle.
Frequently asked questions
What are time-of-use rates for EV charging?
Time-of-use rates are electricity plans that charge different prices depending on the hour. For EV owners, the same 30 kWh session may be cheaper off-peak and more expensive during peak periods.
Is it cheaper to charge an EV at night?
In many utility plans, yes. Overnight hours frequently fall into an off-peak window, but the exact hours vary by utility, season, weekday or weekend schedule, and plan design.
How much can I save with off-peak EV charging?
Savings depend on monthly charging kWh and the gap between the standard rate and off-peak rate. In the 1,000-mile example in this guide, the savings are about $22.22 per month or $266.64 per year.
Are TOU rates worth it for every EV owner?
No. Lower EV charging cost can be offset by higher peak charges elsewhere in the home. The best choice depends on EV charging behavior and whole-home electricity use.
Does Level 2 charging save more money on TOU rates?
Level 2 does not create a lower per-kWh price by itself. Its advantage is speed: more energy can fit inside a limited off-peak window before peak pricing starts.
What is the best time to charge an electric car?
Start with your utility's off-peak period, which is often overnight. There is no universal U.S. charging time that is cheapest everywhere.
Can a TOU plan increase my electric bill?
Yes. If your household uses a lot of electricity during expensive peak periods, a TOU plan can raise your total bill even if your EV charging cost goes down.
Do all utilities offer EV charging rates?
No. Utility offerings vary. Some provide whole-home TOU plans, some offer EV-only meters, some offer managed-charging credits, and some do not offer a standard EV-specific tariff in every service area.
Should I choose an EV-only utility rate?
An EV-only rate can make sense when EV charging can be isolated from the rest of the home, but compare added meter fees, installation costs, and plan restrictions before choosing it.
How do I calculate off-peak charging savings?
Start with monthly wall kWh, then multiply by the difference between the standard rate and the off-peak rate: Monthly savings = EV kWh per month x (standard rate - off-peak rate).
Source notes
This guide uses official federal energy references for TOU and EV charging behavior, plus utility examples to show how plan design can differ by service territory. Utility rates and windows can change; verify the live tariff before switching plans.