Smart Meter & Time-of-Use Tariff Savings Calculator

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.

What's the key thing to understand about How Smart Meters Enable (But Don't Guarantee) Savings?

A smart meter itself doesn't reduce energy usage or cost directly — it's a measurement and communication device, not an energy-saving device — but it enables several genuine opportunities for savings that are difficult or impossible to achieve with an older mechanical meter. Accurate, automatic billing based on genuine usage (rather than estimated bills that can over- or under-charge for extended periods between manual readings) ensures households pay for what they actually use rather than an estimate that might be wrong in either direction for months at a time. Access to a connected in-home display or smartphone app showing real-time or near-real-time usage helps households identify which appliances or habits are driving the biggest share of their bill, since seeing usage spike visibly when a particular appliance switches on (an immersion heater, an electric shower, a tumble dryer) makes the cost of specific habits far more tangible than an abstract total on a quarterly bill. Smart meters are also the technical prerequisite for accessing more sophisticated tariff options like time-of-use pricing, which can offer genuine savings for households able to shift usage to cheaper periods. None of these benefits are automatic, though — a smart meter installed but never checked, with no behaviour change and no switch to a tariff that suits the household's usage pattern, delivers essentially the same bill as the old mechanical meter would have, just measured and billed more accurately rather than genuinely reduced.

What should I know about Realistic Savings from Behaviour Change Prompted by Smart Meter Data?

The actual savings many households achieve purely from having better visibility of their usage through a smart meter and in-home display tend to be modest but genuine — various studies and energy supplier data have generally found that simply having visible, real-time usage information prompts most households to make small behavioural adjustments (turning things off rather than leaving them on standby, noticing and addressing a few particularly costly habits, being more conscious about heating and hot water use) that collectively produce a measurable but not dramatic reduction in overall usage, commonly in the low single-digit percentage range for many households, though this varies considerably depending on how actively a household engages with the available data. Larger savings typically require more deliberate action beyond simply having the data available — actually switching to a time-of-use tariff and genuinely shifting usage patterns to take advantage of it, identifying and replacing an unusually inefficient appliance that the visible data reveals is costing more than expected, or addressing a previously undetected issue like a faulty appliance drawing power continuously that the household wasn't aware of before seeing detailed usage data. Setting realistic expectations about the scale of savings available purely from the meter itself, while recognising its real value as a tool that makes further, more deliberate savings measures both possible and easier to identify, gives a more accurate picture than expecting a smart meter installation alone to produce dramatic bill reductions.

Reference: Realistic Savings From Smart Meter-Driven Behaviour Change

The most consistently documented effect across UK smart meter rollout studies is the smallest one on this list — the 2-5% saving from simple awareness and feedback — because it requires no tariff switch, no new equipment and no behaviour beyond occasionally checking the in-home display or app; the larger savings all depend on taking an additional active step, like switching tariff or fixing a faulty appliance, not from the meter itself.

Worked Example: Annual Saving From Combined Smart Meter Benefits

A household with an annual electricity bill of £900 experiences three separate, stackable effects after getting a smart meter: a 3% saving from general awareness (£27), discovers via the app's usage graphs that an old fridge-freezer is drawing power unusually consistently overnight and replaces it, cutting roughly £70 a year, and switches to a time-of-use tariff that saves a further 6% on the remaining usage after the fridge fix (roughly £48). Total estimated saving = £27 + £70 + £48 = £145/year, or about 16% of the original £900 bill This combined figure is higher than any single effect in isolation, which is the realistic way to think about smart meter savings: the meter itself is an enabling tool, not a savings mechanism on its own, and the actual pound figure saved depends on how many of the available follow-up actions — tariff switching, appliance monitoring, behaviour change — a household actually takes, which is why claimed "average smart meter savings" vary so widely between different sources.

Is Your Smart Meter Actually Working in 'Smart Mode'?

A meter that was installed as a smart meter but has lost its wireless connection to the national Data Communications Company network — often because of poor signal in rural areas, thick walls, or a change of broadband provider — quietly falls back to working like a traditional dumb meter. It still records usage, but it stops sending automatic readings, the in-home display may show nothing useful, and time-of-use tariffs that depend on half-hourly data can't be billed accurately, sometimes defaulting the household to estimated bills again.

If savings from a time-of-use tariff seem to have stalled or bills have reverted to 'estimated', it's worth checking the in-home display is still receiving live data, or asking the supplier for a signal strength check, before assuming the tariff itself isn't delivering.