Ontario’s Ultra-Low Overnight (ULO) Electricity Rate Plan
Last updated: July 2026 · Reviewed by Xolar
Ultra-Low Overnight (ULO) is one of three electricity price plans available to Ontario residential and small business customers, alongside Time-of-Use and Tiered. It pairs the cheapest overnight power in the province with the most expensive weekday evening rate — which makes it excellent for some households and a costly mistake for others. Here’s how it works, what it currently costs, and who it actually suits.
Current ULO rates and hours
These are the Ontario Energy Board (OEB) Regulated Price Plan ULO rates in effect from November 1, 2025 through October 31, 2026. Unlike Time-of-Use, ULO windows do not change seasonally:
| Period | Hours (all year) | Rate |
|---|---|---|
| Ultra-low overnight | Every day 11 p.m.–7 a.m. | 3.9¢/kWh |
| Weekend off-peak | Weekends & 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 |
Energy (supply) rates only — your bill also includes delivery, regulatory and other charges. The OEB resets these rates every November 1.
The spread is the whole point: 39.1¢ on-peak is exactly ten times the 3.9¢ overnight rate. ULO rewards households that can move consumption into the overnight window and punishes those that can’t avoid the 4–9 p.m. block.
ULO vs Time-of-Use vs Tiered
All three plans are available province-wide, and you can switch by contacting your utility.
- Ultra-Low Overnight: 3.9¢ overnight, up to 39.1¢ weekday 4–9 p.m. Best for overnight EV charging and homes with battery storage.
- Time-of-Use: 9.8¢ off-peak / 15.7¢ mid-peak / 20.3¢ on-peak, with windows that shift seasonally. Best if you can shift some load to evenings and weekends but can’t concentrate it overnight.
- Tiered: 12.0¢ up to the monthly threshold (1,000 kWh in winter, 600 kWh in summer for residential), 14.2¢ above it, at any hour. Best for steady usage that’s hard to time-shift.
For the full breakdown of all three plans and their peak hours, see our guide to current Ontario electricity rates.
Who ULO actually suits
ULO is a good fit if you can answer yes to at least one of these:
- You charge an EV at home overnight. Charging between 11 p.m. and 7 a.m. at 3.9¢/kWh is the cheapest way to fuel a vehicle in Ontario.
- You have home battery storage. A battery can charge overnight at 3.9¢ and discharge through the 4–9 p.m. on-peak block, avoiding 39.1¢ power — a spread of more than 35¢/kWh.
- Your household is genuinely out during weekday evenings, so the 4–9 p.m. window is naturally low-usage.
It’s a poor fit for households that cook, run laundry and heat or cool heavily between 4 p.m. and 9 p.m. on weekdays — the on-peak rate is roughly double the equivalent Time-of-Use on-peak rate.
How ULO works with solar
Solar and ULO complement each other well. Your panels generate through the middle of the day, covering the mid-peak window and the start of the on-peak block, while the grid power you still buy comes largely from the overnight ultra-low window at 3.9¢. You offset your most expensive hours with your own generation and buy your cheapest hours from the grid.
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Pairing solar with home battery storage takes it further: the battery charges overnight at the ultra-low rate or from surplus solar during the day, then carries the house through the 4–9 p.m. peak. That’s load shifting, and ULO’s ten-to-one spread makes it more worthwhile in Ontario than under either other plan.
Worth knowing: net-metering customers were historically moved onto the Tiered plan by default after installing solar. You are entitled to choose your plan — so it’s worth checking which one you’re actually on and whether it still suits your usage.
How to switch to ULO
ULO is available to residential and small business customers across Ontario — contact your utility (Toronto Hydro, Hydro One, Hydro Ottawa, Alectra, London Hydro or whichever serves your address) to change plans. The OEB also publishes guidance on choosing your electricity price plan.
Frequently asked questions
What is Ontario’s ultra-low overnight rate?
3.9¢/kWh, every day from 11 p.m. to 7 a.m., under the OEB rates in effect to October 31, 2026. It is the lowest regulated electricity rate available in Ontario.
What are ULO peak hours?
Weekdays 4 p.m. to 9 p.m., year-round, at 39.1¢/kWh. Unlike Time-of-Use, ULO windows do not shift between summer and winter.
Is ULO cheaper than Time-of-Use?
Only if you can concentrate usage overnight. ULO’s overnight rate is far cheaper than TOU off-peak (3.9¢ vs 9.8¢), but its on-peak rate is nearly double (39.1¢ vs 20.3¢). Households that use a lot of power on weekday evenings usually pay more on ULO.
Is ULO good for EV charging?
Yes — overnight charging at 3.9¢/kWh is the cheapest regulated rate in Ontario, which is what makes ULO attractive to EV owners.
Can I switch plans?
Yes. Residential and small business customers can switch between ULO, Time-of-Use and Tiered by contacting their utility.
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For incentive details, see our guide to the Canada Greener Homes programs and what replaced them.