Time-of-use (TOU) plans charge different prices at different hours - cheap overnight, expensive late afternoon. An EV is the largest flexible load in your house, which makes TOU either the best deal in home energy or a quiet way to pay more. Here is how to tell which side you land on.
Why EVs and TOU are made for each other
Your car needs energy, not a schedule. A 60 kWh battery refilling overnight at 7 kW needs about 9 hours - it does not care whether those hours start at 11 PM or 1 AM. Meanwhile the grid's cheapest, cleanest hours are exactly the ones you are asleep in. Typical TOU windows in 2026:
| Plan style | Peak | Off-peak | Spread |
|---|---|---|---|
| Standard TOU (many US utilities) | $0.30-$0.50/kWh, 4-9 PM | $0.10-$0.18/kWh, 11 PM-6 AM | 2-4x |
| Dedicated EV overnight plan | Standard rates by day | $0.05-$0.12/kWh, midnight-6 AM | 3-5x vs day rate |
| UK smart tariff (Octopus Intelligent etc.) | £0.25-£0.30/kWh | £0.07-£0.10/kWh, 6+ night hours | 3-4x |
| AU controlled-load / EV plans | A$0.40-A$0.55/kWh peak | A$0.08-A$0.20/kWh off-peak | 3-5x |
Representative published rates from major US, UK and Australian utilities, November 2026. Your utility's exact windows and prices decide everything - find them before switching.
The break-even math
The question is never "is off-peak cheaper" - it is whether the EV's off-peak savings outweigh the higher peak prices the rest of your house will pay. Worked example, US household using 900 kWh/month of which 300 kWh is EV charging:
| Flat rate $0.17 | TOU (EV 100% off-peak) | TOU (household drifts into peak) | |
|---|---|---|---|
| EV charging, 300 kWh | $51.00 | 300 x $0.11 = $33.00 | $33.00 |
| Rest of house, 600 kWh | $102.00 | 600 x $0.20 avg = $120.00 | 600 x $0.24 avg = $144.00 |
| Monthly total | $153.00 | $153.00 - wash | $177.00 - you lose |
Notice the trap: at a modest peak/off-peak spread, TOU only breaks even even when every EV kWh lands off-peak. TOU wins decisively when the spread is wide (dedicated EV plans), when the EV share of your usage is large (high-mileage drivers), or when you can also shift the dishwasher, laundry and water heating out of peak hours.
Who should switch
- High-mileage drivers (12,000+ miles/year): the EV is a third or more of your usage; wide-spread plans save $25-60/month.
- Households that can automate. Charger scheduling or the car's own timer makes off-peak charging automatic. If it relies on remembering, it will fail.
- Anyone on a dedicated EV tariff (UK Octopus-style, US utility EV plans, AU controlled load): these are designed so you essentially cannot lose, and some guarantee a minimum cheap window.
Who should stay on a flat rate
- Low-mileage drivers. Charging 100 kWh/month cannot offset pricier peak hours for the whole house.
- Homes with heavy 4-9 PM loads - electric cooking plus AC plus kids' screen time right in the peak window, with no appetite to shift them.
- Solar households already self-consuming midday surplus: their "off-peak" is noon. (AU owners: see the solar note below.)
Before you switch: a 20-minute check
- Pull 12 months of usage from your utility account - most show hourly data if you have a smart meter.
- Estimate your EV kWh: annual miles / 3.5 (miles per kWh) / 12.
- Run both tariffs on your real data. Several utilities have online TOU comparison tools; use them.
- Check exit terms - most TOU plans let you switch back, but some EV plans have 12-month commitments.
What to read next
- Off-peak EV tariffs explained: US, UK and Australia
- What home charging costs per month, by state and country
- Dynamic tariffs: the next step beyond time-of-use
Sources: published residential tariffs from US investor-owned utilities, UK Ofgem-regulated suppliers, Australian default market offers. Worked example uses representative rates, November 2026.