Time-of-Use Tariff

An electricity tariff with different unit rates at different times of day, designed to reward off-peak usage and penalise peak demand.

A Time-of-Use (ToU) tariff charges different unit rates depending on the time of day. The simplest version is Economy 7 (cheap overnight, expensive day) which has been around for decades. Modern smart-meter ToU tariffs are far more granular: Octopus Agile changes price every 30 minutes based on wholesale market conditions, sometimes going negative on windy nights.

For Cornwall households with a heat pump, EV and battery, ToU tariffs are transformative. Charge the battery and EV at 7p/kWh overnight, pre-heat the hot water cylinder when prices are low, and avoid drawing from the grid during the 16:00-19:00 peak. Done well, this can cut annual electricity bills by 40-60% versus a flat tariff.

To use a ToU tariff effectively, you need a SMETS2 smart meter and ideally an automation layer (Octopus Intelligent Flux for batteries, Intelligent Octopus Go for EVs, or Home Assistant for fully custom setups). See our battery storage and EV charging pages.