Ontario hydro explained: TOU vs Tiered vs Ultra-Low Overnight (and when to switch)

Ontario households treat the hydro bill as one number and then pick a price plan from a forum anecdote. The Ontario Energy Board’s Regulated Price Plan (RPP) is three different clocks — Time-of-Use, Ultra-Low Overnight, and Tiered — and they only price the Electricity line. Delivery is still delivery. The Ontario Electricity Rebate is still 23.5% of the eligible base, as of 1 November 2025.

This is an OEB Customer Choice worksheet with the prices in force through 31 October 2026, not a U.S. time-of-use primer and not a retailer-contract pitch. If you rent, decode the lease first in heat included vs hydro. If you already know the house leaks, start with air sealing — a plan switch will not fix a patio door.

What the OEB Regulated Price Plan actually bills (commodity vs delivery)

Your local distribution company (Toronto Hydro, Hydro One, Alectra, Hydro Ottawa, and the rest) prints several blocks. The one Customer Choice edits is the Electricity commodity: TOU periods, ULO periods, or two Tiered prices. That line already includes the Global Adjustment for RPP customers. Delivery, regulatory charges, and HST are separate. The Ontario Electricity Rebate is a pre-HST credit — 23.5% of the eligible base as of 1 November 2025 (O. Reg. 363/16; Hydro One and the OEB RPP backgrounder describe the same change from 13.1%).

Two lessons that save more arguments than they save dollars:

• You cannot elect your way out of poles, wires, and the monthly service charge. A “cheap ¢/kWh” plan that does not match your hours still rides the same delivery.
• Fewer than one in ten Ontario customers buy from an electricity retailer. A retailer contract is not RPP. The OEB does not set that price, and Global Adjustment usually appears as its own line on top. Cancel the contract first if you want TOU / ULO / Tiered back — your first RPP bill may still open on TOU.

Pull twelve months of bills or the utility’s usage download. You want kWh by period (or by hour if you have interval data), not just the amount owing after OER.

Time-of-Use: periods, seasonal hour flips, and who it fits

TOU is the default most people already sit on. Three prices, two seasonal calendars. Prices from 1 November 2025: off-peak 9.8 ¢, mid-peak 15.7 ¢, on-peak 20.3 ¢ per kWh.

The OEB notes that Ontario households already use nearly two-thirds of their electricity in off-peak hours. TOU fits you if laundry, dishwasher, and the dryer can wait until evening or the weekend, and if nobody is home blasting air conditioning through a summer afternoon. It is a weak fit for a work-from-home house that cooks and launders at 5:30 p.m. on weekdays — that is on-peak in winter and mid-peak in summer.

The hour flip on 1 May and 1 Nov is the trap people forget. A “I run the dryer at 2 p.m.” habit is mid-peak in January and on-peak in July.

Ultra-Low Overnight: overnight wins vs weekday 4–9 p.m. pain

ULO has four prices and does not flip hours with the season. From 1 November 2025: overnight 3.9 ¢ (every day 11 p.m.–7 a.m.), weekend/holiday off-peak 9.8 ¢ (7 a.m.–11 p.m.), mid-peak 15.7 ¢ (weekdays 7 a.m.–4 p.m. and 9–11 p.m.), and weekday 4–9 p.m. at 39.1 ¢.

That 39.1 ¢ line is the whole decision. Dinner, screens, the oven, and a heat-pump or baseboard recovery after work all sit in the most expensive five hours of the Ontario RPP. Overnight EV charging, a delayed dishwasher, and a night-shift household can more than pay for it. A family that is home and cooking from 4:30 p.m. usually should not.

ULO is not a retailer gimmick. It is still RPP. You still get OER. You still pay delivery. You just agreed to a steeper clock.

Tiered: summer 600 vs winter 1,000 kWh thresholds and steady users

Tiered ignores the clock. You pay 12.0 ¢ up to the seasonal threshold and 14.2 ¢ after that (1 Nov 2025 prices). Residential thresholds: 600 kWh per month in summer (1 May–31 Oct) and 1,000 kWh in winter (1 Nov–30 Apr). Small-business threshold is 750 kWh all year.

Tiered fits a household that cannot move load — medical equipment, a home office with daytime computing, a caregiver who has to cook at 5 p.m. — and that usually stays under the threshold. It is a poor fit for electric heat, a pool pump, or an EV that charges whenever, because those kWh stack into Tier 2 regardless of the hour.

Labelled sketch, not your bill: 800 kWh in a summer month on Tiered is 600 × 12.0 ¢ + 200 × 14.2 ¢ = $100.40 commodity. The same 800 kWh on TOU depends entirely on when those kilowatt-hours landed. Do not average 12.0 and 14.2 and call it research.

How to run the OEB bill calculator with real usage data

The OEB bill calculator is the official comparison, not a blog spreadsheet. The full workflow — two seasons, Green Button, OER, and the election checklist — is in how to use the OEB bill calculator. Use it like this:

1. Identify your utility / LDC so delivery matches your territory, not a provincial fiction.
2. Enter a recent month you understand, then a January and a July. One shoulder month is not a year.
3. If you have Green Button or interval data, split kWh into the TOU and ULO buckets yourself and sanity-check the calculator. An EV that charges at 1 a.m. will lie if you type “typical” residential percentages.
4. Compare the Electricity line across the three plans, then look at the all-in estimate. OER should apply to all three RPP options.
5. Write the annual difference in dollars — not ¢/kWh — and decide if the lifestyle change is real. A $40 year is not a project.

If the calculator and your last bill disagree by a lot, you have the wrong LDC, the wrong season, or a retailer contract. Fix that before you file anything.

How to file an election form with your local utility

Customer Choice is an OEB rule; the paperwork is your LDC’s. Toronto Hydro’s version is typical (verified 20 Sep 2026):

• Eligible: residential or small commercial under 50 kW peak, buying from the utility, no retailer contract.
• Fastest path: the utility’s self-serve portal. Fallback: a Customer Choice Request Form (PDF) or a phone request.
• If the utility has your request at least 10 calendar days before the next billing period, the new plan starts on that period. Inside 10 days, it may wait until the period after that.
• You can change again later. Nothing is permanent. Doing nothing leaves you on the current plan.
• New-move accounts: pick the plan on the move-in form if the LDC offers it. Transfers after a move may still need a second request.

Hydro One, Alectra, and Hydro Ottawa publish the same idea with their own portals. Search “[your utility] customer choice.” Do not mail a Toronto Hydro PDF to Thunder Bay.

Special cases: EV overnight charging, work-from-home, electric heat

EV overnight. ULO’s 3.9 ¢ overnight commodity is the reason the plan exists. Pair it with a charger on a timer (see Level 2 install cost) so the car is not finishing at 7:15 a.m. on mid-peak. If you also cook and launder from 4–9 p.m., run the calculator with real hours — the 39.1 ¢ block can eat the charging win.

Work-from-home. Daytime computing and a kettle every hour are mid-peak or on-peak on TOU, mid-peak on ULO, and just “kWh” on Tiered. Tiered or TOU with disciplined laundry often beats ULO. A smart thermostat that pre-heats before 4 p.m. on ULO is a behaviour tool, not magic.

Electric heat or a heat pump. Winter kWh explode. Tiered’s 1,000 kWh winter block helps a little; ULO’s 4–9 p.m. recovery after a workday can hurt a lot. Compare in gas vs electric heat and heat pump vs furnace before you elect a clock you cannot live on. Peak Perks is a summer air-conditioning program — it does not change RPP prices; see Peak Perks.

If the honest annual gap is smaller than one dinner out, stay put and seal the attic. If it is a few hundred dollars and the lifestyle is already true (the car charges at 1 a.m.; nobody cooks at 6 p.m.), file the form and calendar the 10-day cut-off.