Smart Meter & Time-of-Use Tariff Savings Calculator
Calculate potential savings from smart meter time-of-use tariffs like Octopus Agile, Intelligent Octopus, and Economy 7.
As an Amazon Associate and CJ Affiliate publisher we earn from qualifying purchases. Prices and availability may vary.
Smart Tariff Guide
How Time-of-Use Tariffs Work?
Smart meters enable electricity suppliers to offer time-varying rates — charging less when grid demand is low (overnight) and more during peak hours. This benefits both consumers (savings) and the grid (demand shifting). Economy 7: the original time-of-use tariff. 7 hours cheap rate overnight (typically midnight-7am or 1am-8am). Standard day rate for remaining 17 hours. Best for: storage heaters, hot water immersion heaters, overnight EV charging. Intelligent Octopus: links to your EV charger or heat pump directly, automatically scheduling charging and heating into the cheapest overnight window without you needing to manually time appliances — the tariff and the smart control work together rather than requiring separate manual timers.
What's the key thing to understand about Octopus Agile?
Octopus Agile: half-hourly rates based on wholesale electricity prices. Rates can go negative during windy/sunny periods — you get paid to use electricity. Rates can be very high during peak demand. Requires: smart meter with half-hourly data enabled. App to check rates in advance. Ability to schedule appliances, EV, heating. Best for: tech-savvy users, EV owners, homes with battery storage. Average savings: 10-25% vs standard tariff for engaged users. Requires active participation — passively following the standard usage pattern without shifting load to cheap periods gains little over a flat-rate tariff, and on the rare days when wholesale prices spike, Agile can be more expensive than a standard tariff during peak hours. Best suited to households genuinely willing to check the app and shift usage, not a "set and forget" choice.
What should I know about EV Charging and Smart Tariffs?
An EV fundamentally changes the economics of smart tariffs. Typical EV consumption: 3,000-6,000 kWh/year for average mileage. At 24p/kWh standard tariff: £720-1440/year. At 7.5p/kWh Intelligent Octopus overnight: £225-450/year. Annual saving: £495-990/year just on EV charging. With an annual electricity tariff standing charge saving of £100-200: a smart tariff can save EV owners £600-1,200/year vs standard. Heat pumps: similar logic. Heat pumps typically use 3,000-8,000 kWh/year for space heating, so shifting even a portion of that consumption to a cheap overnight or off-peak rate — where the heat pump's thermal store or the building's own thermal mass can carry the saved heat through the day — produces savings on a similar scale to EV charging, making combined EV-plus-heat-pump households the biggest beneficiaries of time-of-use tariffs.
What do I need to know about Battery Storage and Solar?
Battery storage unlocks further smart tariff savings: charge battery cheaply overnight. Use stored cheap electricity during expensive peak hours. Solar and battery: sell solar to grid during peak (high export rate). Charge battery from grid overnight at cheap rate when solar insufficient. Octopus Flux tariff: designed for solar + battery households. Import rate overnight ~8p/kWh. Export rate midday ~15p/kWh. Payback on battery (Powerwall ~£9,000): approximately 10-15 years at current rates without solar to charge it for free — pairing a battery with solar generation, so it charges from free daytime export instead of the grid, meaningfully shortens the payback period and is the more common configuration for new installations.