Economy 7

Economy 7 is the name of a differential tariff provided by United Kingdom electricity suppliers that uses base load generation to provide cheap off-peak electricity during the night.

Houses using the Economy 7 tariff require a special electricity meter which provides two different readings - one for electricity used during the day, priced higher, and the other for the night, priced lower. The night (off-peak) period lasts for a total of seven hours, hence the name; however it may or may not be a continuous period, as it may alternate between the two prices during the night.