The default tariff is the expensive one
A standard flat tariff charges the same ~25–27p/kWh whether the grid is drowning in midnight wind power or straining at teatime. Time-of-use tariffs price honestly instead: cheap windows (typically 7–12p/kWh overnight) and dearer peaks. If any of your usage can move — a dishwasher with a delay button counts — you’re leaving money on the table at a flat rate. The only prerequisite is a working smart meter, which your supplier fits free. That makes the smart meter the rare genuinely free upgrade in home energy: it costs nothing and unlocks everything on this page.
EV charging: the headline act
This is often the single biggest saving in the entire home-energy subject. A dedicated EV tariff at ~7p/kWh overnight, in a car doing 3.5–4 miles per kWh, works out around 2p per mile. Petrol is 12–16p per mile; public rapid chargers at 60–85p/kWh are 16–24p per mile. Over a 10,000-mile year, home off-peak charging saves £1,000–£1,400 versus petrol — and needs no panels, no battery and no building work.
The practicalities: a home charge point costs roughly £800–£1,200 installed (7kW, fine for overnight full charges), and the car or charger schedules charging into the cheap window automatically. One caution: some EV tariffs charge a slightly higher peak rate to fund the cheap window — the deal still wins comfortably for anyone charging a car, but do the arithmetic on your own day/night split rather than assuming.
The tariff menu
- EV tariffs — a fixed cheap window (often 5–7 hours overnight) at ~7p. Crucially, the whole house gets the cheap rate in the window, not just the car: run the washing, dishwasher and immersion heater then too.
- Agile / dynamic tariffs — prices change half-hourly with the wholesale market, occasionally going negative (paid to consume) and occasionally spiking. Rewarding for engaged users, home batteries and automation; wrong for set-and-forget households.
- Heat-pump tariffs — cheap rates shaped around heat-pump running patterns; these can tip the heat pump vs gas running-cost comparison decisively.
- Export tariffs (SEG) — the other side of the meter. Rates for exported solar range from ~4p to 15p+/kWh, and shopping the export rate matters as much as the import rate — the solar guide covers it.
What pairs with what
Smart tariffs are the multiplier on everything else in this section. A home battery charged at 7p overnight and discharged at 26p peak earns the spread every day of the year, sunshine optional. Solar pairs with a good export rate. A heat pump turns cheap electricity into 3–4× cheap heat. And an EV is the biggest movable load most households will ever own. The more of these you have, the more a smart tariff is worth — which is why tariff choice belongs in the ROI simulator’s sums, not as an afterthought.
The no-hardware version
No EV, no battery, no solar? Load-shifting still pays: dishwashers, washing machines and tumble dryers have timers, and on an off-peak tariff each shifted cycle costs roughly a third of its peak price. Whether that beats a flat tariff depends on how much of your usage can move — as a rule of thumb, if you can shift a quarter or more of your consumption into the cheap window, a time-of-use tariff wins; if nothing can move, stay flat and just shop the flat rate.
The one-line summary
If you have an EV, a heat pump, a battery — or just a dishwasher with a delay button — a smart tariff is the highest-return, zero-hardware move in home energy: get the smart meter working, do the sums on your own usage split, and shop the export rate as hard as the import rate.
Related guides & tools
- Solar, batteries and smart tariffs — how tariffs interact with panels and storage
- Heat pumps vs gas boilers — the running costs a tariff can transform
- Heating controls — controlling when you use heat pairs with when you buy it
- Solar & Battery ROI Simulator — run tariff scenarios against your own numbers
Last reviewed: July 2026.