Time-of-Use Battery Savings Estimator

A battery charged in the cheapest hours and used in the on-peak hours moves that electricity to the lower price. The estimate takes the plan's cheapest price and its on-peak price: on Time-of-Use, off-peak at 9.8 and on-peak at 20.3 cents per kWh; on Ultra-Low Overnight, ultra-low overnight at 3.9 and on-peak at 39.1 cents per kWh.

Charging costs the kilowatt-hours moved, divided by the round-trip efficiency, at the cheap price, because some energy is lost on the way in and out. The on-peak electricity it replaces is the kilowatt-hours moved at the on-peak price. The saving per weekday is the difference, and the saving per year is that times the weekdays you enter. Weekends and holidays have no on-peak period.

The prices are the Ontario Energy Board's Regulated Price Plan prices, effective 2025-11-01 and checked 2026-09-25; the hours of each period, which change with the season on Time-of-Use, were checked 2026-10-01. These prices already include an estimate of the Global Adjustment and exclude delivery, regulatory charges and tax. The Ontario Energy Board sets these prices once a year on November 1, so check the current prices before you decide anything. Ontario Energy Board electricity rates →

A battery that has discharged at the peak to shift your usage cannot also be full for an outage at that moment. Keeping a reserve for outages leaves less to shift. A licensed electrician sets up the backup and charging settings with you when the system is installed.