Single Rate: you’re charged at a flat rate for the electricity you use no matter what time of day.

Time of Use: you’re charged different rates at different times of day, which may include peak, off-peak and shoulder periods. Peak times are generally when electricity is being used the most (and are therefore the most expensive), and off-peak periods are the quieter times, when electricity is the cheapest. Shoulder rates are periods between peak and off-peak periods, and are usually a bit cheaper than peak rates. These rates may also change by season throughout the year.

Controlled Load: you may also be charged for electricity supplied to a specific stand-alone appliance, such as an electric hot water system or underfloor heating, at a different rate to your other electricity usage. This tariff is usually only used for appliances that run overnight or in off-peak times. So controlled load rates are usually lower than other rates.

Demand: Instead of measuring your usage over time, demand (measured in kWh) is a measure of how intensely you use electricity at a point in time. Therefore, your demand will be high when you have many appliances on at the same time. Different retailers have different ways of applying demand charges, for example, you may be charged for your highest demand in a period of time, an average of peak demand over a period of time or different demand rates in different seasons.