Ontario Hydro Bills Shift to Summer Time-of-Use Rates on May 1 — Here's How to Adjust Your Usage and Save

The Summer TOU Schedule, Hour by Hour

Ontario's seasonal TOU framework is built around a simple premise. Weekday electricity demand peaks at different hours in summer than in winter, and the price calendar follows. In winter, demand concentrates at the mornings-and-evenings bookends of a workday, when people are heating homes, cooking, and getting ready. In summer, demand shifts to the middle of the day, when air conditioners run hardest. The schedule reflects that.

Under the summer TOU periods that take effect May 1, the Ontario Energy Board sets on-peak at weekdays 11 a.m. to 5 p.m., mid-peak at weekdays 7 a.m. to 11 a.m. and 5 p.m. to 7 p.m., and off-peak at weekdays 7 p.m. to 7 a.m. Weekends and statutory holidays stay off-peak around the clock — that rule does not change between seasons.

The on-peak rate is more than twice the off-peak rate. That spread is the whole reason the schedule matters. A kilowatt-hour consumed at 2 p.m. on a weekday in July costs 107% more than the same kilowatt-hour consumed at 9 p.m. the same day. Behaviour that was neutral in winter — running a load of laundry after lunch, for example — becomes the single most expensive time of the week.

Hours Move, Prices Don't

This is the subtlety buried under most headlines. The OEB sets TOU prices once a year, on November 1, and they remain in effect until the following October 31. The current prices — 9.8¢ off-peak, 15.7¢ mid-peak, 20.3¢ on-peak — were set November 1, 2025, and apply through October 31, 2026. The May 1 transition does not adjust the rates themselves. It only reassigns which hours fall into which bucket.

The practical takeaway: if you paid attention to last November's rate adjustment, you already know what summer will cost. The question on May 1 is purely behavioural — where do the expensive hours land, and what's running inside them?

TOU vs. Tiered vs. Ultra-Low Overnight

Not every Ontario customer is on a time-based plan. The province's Regulated Price Plan offers three options — Time-of-Use, Tiered, and Ultra-Low Overnight (ULO) — and the May 1 transition hits each one differently. The OEB's guide to choosing an electricity price plan confirms that most residential and small-business customers pay TOU prices by default.

TOU customers are directly affected by the hour shift. If your bill shows on-peak, mid-peak, and off-peak line items, the summer schedule governs which of your weekday hours are expensive for the next six months.

Tiered customers aren't affected by the hour change, because their price depends on total monthly consumption rather than time of day. But there's a seasonal twist that often gets missed: the Tier 1 threshold drops from 1,000 kWh per month in winter to 600 kWh per month in summer for residential customers, while Tier 1 sits at 12.0¢ and Tier 2 at 14.2¢. More of your summer usage spills into the higher-priced bucket than it would in winter. The small-business threshold of 750 kWh per month does not change seasonally.

ULO customers are also unaffected by the May 1 transition, since ULO periods are the same year-round. ULO concentrates the lowest rate (3.9¢/kWh) into the overnight 11 p.m. to 7 a.m. window every day, with an on-peak window of 4 p.m. to 9 p.m. on weekdays at 39.1¢/kWh. That's the highest on-peak rate of any RPP plan, which is why ULO tends to make sense only for households with large overnight loads — typically EV charging.

How to Verify Your Plan

Your rate plan is disclosed on your bill, usually in the detail portion of the Electricity line. The phrase to look for is literal: "Time-of-Use," "Tiered," or "Ultra-Low Overnight." If you've never actively chosen a plan, you're most likely on TOU — that's the default across the province.

Switching between the three RPP plans is free and can be done by contacting your local distributor. The OEB also runs a bill calculator that lets you plug in a month of usage and compare what you'd pay under each plan. Five minutes with it, using a recent bill, settles the question. It's worth the check before summer, especially if your household has added anything meaningful to its load in the past year — an EV, a heat pump, a home office with heavy daytime electronics use.

Cooling Is the New Priority Load

Air conditioning is the single largest reason the summer on-peak window sits in the middle of the day. When temperatures climb, cooling loads climb with them, and that demand pattern is exactly what the TOU schedule is priced against. A home running central AC through a July heat wave consumes the most electricity at precisely the hours those kilowatt-hours cost the most.

The best lever here is pre-cooling. A smart or programmable thermostat can bring the home to a cooler setpoint during the off-peak or mid-peak morning — say, 6 to 10 a.m. — and then let the temperature drift up a few degrees across the on-peak block. The envelope of the house acts as thermal storage. You're not skipping cooling, you're timing it. Households without smart thermostats can achieve a coarser version of the same thing by manually bumping the setpoint two or three degrees at 11 a.m. and dropping it again at 5 p.m.

A handful of envelope moves compound this. Closing blinds on west- and south-facing windows during peak sun reduces solar gain. Sealing gaps around doors and windows limits the cool air that leaks out. Ceiling fans let you raise the thermostat setpoint without feeling warmer — fans cool people, not rooms, so turn them off when you leave.

Flexible Loads: Laundry, Dishwashing, EV Charging

These are the easiest wins, because the timing is fully under your control. Laundry, dishwashing, and EV charging run on schedules you set, not schedules the weather sets.

For laundry and dishwashing, the summer target is simple: after 7 p.m. on weekdays, or anytime on weekends and holidays. Most modern machines have delay-start timers that will launch a load at a set hour. Washing clothes in cold water reduces the kilowatt-hour load per cycle regardless of when you run it, so that habit stacks cleanly with the timing shift.

EV charging has the biggest absolute dollar impact, because a typical overnight charge pulls 30 to 60 kWh — enough that a single on-peak session can cost more than a week of off-peak sessions. Level 2 home chargers almost universally support scheduled charging (the full setup is covered in our home EV charging guide). Set the charger, or the vehicle itself, to begin drawing power at 7 p.m. or later. Households with meaningful daily EV miles should also run the OEB bill calculator on ULO versus TOU — the overnight 3.9¢ ULO rate often beats off-peak TOU on charging cost alone, though the 39.1¢ weekday on-peak penalty has to be weighed against it.

Loads That Don't Move

Some loads run around the clock and can't meaningfully be shifted: refrigerators, freezers, networking equipment, standby electronics, and anything plugged in for comfort or safety. The lever here isn't timing — it's reducing consumption. Replacing older bulbs with LEDs, unplugging idle electronics, and switching off the "always-on" standby modes on entertainment systems all help. According to the OEB's consumer bill brochure, Ontario households already consume nearly two-thirds of their electricity during off-peak hours. The remaining third — split between mid-peak and on-peak — is where optimization lives.

Think of this as a one-hour, one-time setup that pays out for the next six months.

Start with the thermostat. If you have a smart thermostat, program two summer schedules. The weekday schedule pre-cools the home between 6 and 10 a.m., allows a modest drift (2 to 4 degrees warmer) from 11 a.m. to 5 p.m., and returns to comfort settings at 5 p.m. The weekend schedule runs at comfort settings all day, since weekends are off-peak. Households considering a bigger cooling upgrade can also work through the case for a heat pump alternative in our guide to switching from an air conditioner to a heat pump, since heat pump systems have their own TOU-friendly operating profiles.

Move to appliances. Set the dishwasher to delay-start after 7 p.m. every weekday. Plan laundry days for weekends, or use the machine's timer for late-evening weekday runs. Unplug phone chargers, small appliances, and standby electronics that draw power when idle.

If you have an EV, update the charge schedule on the vehicle or the charger to start at 7 p.m. or later on weekdays, with a full-power window through the overnight hours. If you have other schedulable equipment — pool pumps, electric water heaters with timer controls, dehumidifiers — move their run windows into off-peak.

Finally, verify your plan. Pull your most recent bill, confirm whether you're on TOU, Tiered, or ULO, and run one comparison in the OEB bill calculator. A household that added an EV last winter may find ULO now pencils out. A low-consumption household with most of its use already concentrated overnight may prefer Tiered. Most households will stay on TOU — but the five-minute check is worth doing once.

The first summer TOU bill will land in June. A few things to cross-check. The Electricity line should show separate entries for on-peak, mid-peak, and off-peak consumption, with the summer hour definitions in effect. Off-peak should remain the largest bucket — if it isn't, the timing shifts haven't fully landed yet. The Ontario Electricity Rebate continues to apply to the electricity portion of the bill regardless of rate plan, so the net cost per kilowatt-hour looks lower than the headline TOU rates once the rebate line is applied; for the broader context of how provincial electricity charges have moved recently, our coverage of the rare credit on Ontario bills as the Global Adjustment went negative lays out the underlying math.

The May 1 transition doesn't reward dramatic lifestyle changes. It rewards small, durable habits — pre-cool, delay-start, charge overnight, confirm the plan. Done once at the start of summer, those habits capture most of what's available to capture.