Smart Meter Tariff & Peak vs Off-Peak Savings Calculator
Calculate potential savings from a smart time-of-use electricity tariff. See how shifting appliances and EV charging to off-peak periods could cut your electricity bill.
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Smart Tariff Guide
What should I know about Time-of-Use Tariffs in the UK?
Smart time-of-use tariffs charge different rates at different times of day, incentivising shifting demand away from peak periods. Popular options in 2024: Octopus Agile: half-hourly variable rates linked to wholesale prices. Very cheap or even negative overnight (October-March). Best for flexible users with smart appliances. Octopus Go: fixed cheap rate at night (typically 7p-9p/kWh midnight-5am or 11.30pm-5.30am) with a standard daytime rate. Excellent for EV owners. Economy 7: old overnight tariff structure predating smart meters, still available on many suppliers' books — 7 hours of cheap overnight electricity (roughly midnight-7am, timing varies by region) with a higher day rate for the rest. Less flexible than newer smart tariffs since the cheap window is fixed rather than tracking actual demand or wholesale prices, but still worthwhile for households with storage heaters or immersion heaters that can be timed to run overnight.
What You Can Shift to Off-Peak?
Easily shiftable loads: EV charging (timer on charge points — biggest opportunity). Dishwasher (set delay start). Washing machine (set delay start). Tumble dryer (set delay start). Battery storage (charge overnight, discharge in peak periods). Immersion heater (timer to heat water overnight). Less flexible: cooking (mostly peak time). Heating (thermostat can be scheduled but thermal comfort limits). Lighting (mostly evening peak). The biggest single opportunity for most households: EV charging.
What do I need to know about Smart Meters and Agile Tariffs?
Smart tariffs require a smart meter (SMETS2). Contact your supplier if you do not have one — installation is free and suppliers are required to offer them. Smart meter does NOT change your tariff automatically — you must switch to a smart tariff after installation. Octopus Agile rates: published 4-5pm daily for the following day. Cheapest periods typically 2am-6am (grid demand lowest) and during high renewable generation (windy days). Plunge pricing: during very high wind output, rates sometimes drop below zero, meaning Agile customers are effectively paid to use electricity during those windows — running a washing machine, dishwasher, or EV charge during a plunge-pricing period can turn an ordinary chore into a small credit on the bill. The Octopus app sends alerts when plunge pricing is forecast.
Is a Smart Tariff Right for You?
Smart tariffs are best for: EV owners (large overnight charging demand). Houses with battery storage. Households with smart appliances (connected washing machine, dishwasher). People who work from home and can be flexible about when to run appliances. Smart tariffs are less suitable for: households that cannot shift any load (elderly residents who need heating/hot water during the day, no EV). Those with prepayment meters (limited compatibility). The key question: how much of your electricity usage can realistically be shifted to off-peak hours. A household that can move EV charging, laundry, dishwashing, and battery charging overnight stands to save significantly; one that mostly uses electricity during the day for cooking and general appliances, with no flexible loads, will see little benefit and may be better off on a simple fixed-rate tariff.