Time-of-use (TOU) electricity rates charge different prices depending on when you use power: more at busy times of day, less overnight and on weekends. An ultra-low overnight (ULO) plan, offered in Ontario, takes that further with a very cheap overnight price and a very expensive late-afternoon peak. Whether either saves you money depends on how much of your usage you can shift into the cheap hours.
Key takeaways
- TOU pricing reflects how demand, and the cost of supplying power, changes through the day.
- Ontario households can choose between time-of-use, tiered and ultra-low overnight pricing on regulated rates.
- ULO rewards households that can move large loads, like EV charging or water heating, to between 11 p.m. and 7 a.m.
- The ULO on-peak price is high, so households with heavy weekday late-afternoon use can end up paying more.
- Several other provinces and utilities offer or are testing time-varying rates; check with your utility.
Why electricity prices vary by time
Electricity demand peaks when people get home, cook, run laundry and heat or cool their homes. To meet those peaks, grids need extra generation and wire capacity that sits idle much of the day. Overnight, demand drops and there is often surplus low-cost and low-emission power available.
Time-varying rates send that signal to customers. If enough households shift flexible loads off-peak, the grid needs less peak capacity over time, which helps hold down system costs for everyone. You can learn more about how grids balance supply and demand on our future of energy page.
How Ontario's plans compare
The Ontario Energy Board (OEB) sets regulated prices for most households and typically updates them each November 1. The prices below are the ones set for November 1, 2025, rounded, and are shown to illustrate the structure. Check the OEB or your utility for the current figures before deciding.
Time-of-use (winter hours)
| Period | Hours | Approx. price |
|---|---|---|
| Off-peak | Weekdays 7 p.m.–7 a.m., all day weekends and holidays | 9.8¢/kWh |
| Mid-peak | Weekdays 11 a.m.–5 p.m. | 15.7¢/kWh |
| On-peak | Weekdays 7–11 a.m. and 5–7 p.m. | 20.3¢/kWh |
In summer, the mid-peak and on-peak blocks swap, because air conditioning pushes peak demand into the afternoon.
Ultra-low overnight (year-round)
| Period | Hours | Approx. price |
|---|---|---|
| Ultra-low overnight | Every day 11 p.m.–7 a.m. | 3.9¢/kWh |
| Weekend off-peak | Weekends and holidays 7 a.m.–11 p.m. | 9.8¢/kWh |
| Mid-peak | Weekdays 7 a.m.–4 p.m. and 9–11 p.m. | 15.7¢/kWh |
| On-peak | Weekdays 4–9 p.m. | 39.1¢/kWh |
Tiered
Tiered pricing charges one price for the first block of electricity each month and a higher price above it, regardless of time. The winter residential threshold is 1,000 kWh per month and the summer threshold is 600 kWh. It can suit households that use a lot of power during the day and cannot shift it.
Remember: these prices cover only the electricity itself. Delivery, regulatory charges and taxes still apply, and the Ontario Electricity Rebate is credited on top. Our guide on how to read your electricity bill walks through those lines.
Who benefits from ultra-low overnight
ULO tends to work well if you:
- Drive an EV. Charging overnight at the ULO price can make home charging very inexpensive. Most EVs and Level 2 chargers let you schedule charging; our electric vehicles page explains the options.
- Have an electric water heater on a timer, especially a large tank that can heat overnight and coast through the day.
- Can run laundry, dishwashers and dehumidifiers late at night.
- Have a home battery that can charge overnight and discharge during the 4–9 p.m. peak.
- Are often away weekday afternoons and evenings, or can pre-heat or pre-cool before 4 p.m.
ULO may not suit you if:
- Someone is home all weekday afternoon running heating or cooling with little flexibility.
- You cook, do laundry and use electric heat mostly between 4 and 9 p.m.
- You cannot easily automate or shift loads.
Working out whether to switch
- Download your hourly data from your utility's online portal.
- Total your weekday 4–9 p.m. usage and your 11 p.m.–7 a.m. usage.
- Estimate what you could shift. EV charging and water heating are the easiest.
- Use a calculator. The OEB and many utilities offer bill comparison tools.
- Try it for a season. In Ontario you can generally switch between plans, so you are not locked in, though check timing rules with your utility.
Heat pumps and time-varying rates
Heat pumps add significant winter electricity use, much of it in the morning and evening. On ULO, a 4–9 p.m. peak during a cold snap can be costly. Strategies include pre-heating slightly before 4 p.m., keeping temperatures steady rather than using deep setbacks, and improving insulation so the house holds heat longer. Some smart thermostats can automate this; see our post on whether smart thermostats really save money. For heat pump basics, visit our heat pumps and geothermal page.
Beyond Ontario
Time-varying rates are spreading. Some utilities in other provinces have introduced optional time-of-use plans, EV-specific rates or overnight discounts, while others are running pilots. In Alberta's competitive retail market, some retailers have offered plans with time-based pricing. Programs and prices change, so check your utility's website or our province guides.
Frequently asked questions
Is ultra-low overnight worth it without an EV?
Sometimes. If you can shift water heating, laundry and dishwashing to overnight and keep 4–9 p.m. weekday use low, you may still save. Without big shiftable loads, the high on-peak price often cancels out the benefit.
Do I need a new meter to switch?
In Ontario, smart meters are already installed in nearly all homes, so switching plans is usually just a request to your utility.
Can solar panels help on time-of-use?
They can offset daytime usage, but most solar output happens around midday, and production fades during the 4–9 p.m. ULO on-peak window, especially in winter. Pairing solar with a battery that discharges during peak hours makes better use of time-varying prices.
The bottom line
Time-of-use rates reward flexibility. If you can move big loads like EV charging and water heating into the overnight hours, plans like ultra-low overnight can noticeably cut your energy costs; if most of your usage is fixed in the late afternoon, standard TOU or tiered pricing may be the safer choice. Let your own hourly data decide.
Sundamentals is an independent, non-profit education platform. Program details and prices change often — check current programs for your address in our rebate finder.