What is a time-of-use electricity tariff and should I switch?

Standard electricity tariffs charge you the same price per kWh all day. Time-of-use (TOU) tariffs charge different prices depending on when you use electricity. The most popular in the UK: Octopus Go (cheap rate ~7–9p/kWh between midnight and 5am, standard rate ~25p during the day). Octopus Agile (prices vary every 30 minutes based on wholesale market — can be negative in windy periods). Economy 7 (cheap overnight rate for 7 hours — older system, mostly for storage heaters). Who benefits: if you have an electric vehicle and charge overnight, a TOU tariff can save £500–1,000 per year. If you have a battery, you charge it cheaply overnight and use it during peak hours. If you have solar and a battery, combine solar self-consumption with cheap overnight top-up. You need a smart meter to access TOU tariffs. The savings depend entirely on whether you can shift your electricity use to cheaper periods.