Economy 7 and Smart Tariffs Explained: Shift the Big Loads, Cut the Bill

The simplest way to cut an electricity bill isn't new kit — it's paying less per unit for the energy you already use. Time-of-use tariffs give you cheap electricity in an overnight window in exchange for a dearer daytime rate. If you can move your heaviest loads — hot water, an EV, the washing — into that window, you win. If you can't, you can easily end up paying more. This guide explains how it works and, honestly, when it won't pay.

What Economy 7 and smart tariffs actually are

Economy 7 is the legacy version: you get roughly seven cheap overnight hours and pay a higher rate the rest of the day. It's been around for decades and is widely available — good for storage heaters, a home battery and heating your hot water cylinder overnight.

Smart tariffs are the modern cousins, and they need a smart meter (SMETS2). The shapes vary:

• Intelligent Octopus Go — a cheap overnight window aimed at EV and battery charging (verify the current rate and hours before relying on them).
• Cosy Octopus — cheap windows tuned around heat-pump running costs.
• Agile Octopus — half-hourly pricing linked to the wholesale market; it can even go negative on windy or sunny days, but only suits engaged users who can shift load on the day.

These are indicative examples, not recommendations — and rates change with 30 days' notice, so always check the live figure on the supplier's page.

Which loads are worth shifting

The whole game is moving kWh out of the expensive daytime and into the cheap window. The big, shiftable loads are:

• EV charging — the single biggest prize. A car drinking tens of kWh a week in the cheap window transforms the maths.
• Hot water — an immersion on a timer heats the cylinder overnight; a solar diverter can top it up with surplus PV in daylight.
• Home battery charging — charge cheap overnight, use it during the pricey daytime peak.
• Washing machine and dishwasher — run on a delay timer into the window (mind noise and fire-safety guidance on unattended appliances).

The more of your total consumption you can park in the cheap hours, the better these tariffs work.

Here's the catch — it might not pay for you

The daytime rate on a time-of-use tariff is higher than a standard single-rate deal. The saving depends entirely on what share of your usage you can genuinely move overnight.

Watch for these:

• No EV, no battery, no electric heating? There may be little to shift — the daytime premium can outweigh the overnight discount.
• Daytime-heavy households — if someone's home all day using power, Economy 7 often works against you.
• Standing charges still apply on top of unit rates, and they vary by region. Don't compare tariffs on the overnight p/kWh alone.
• The cheap window is finite — around seven hours on Economy 7. Over-stuff it and some load spills into the dear rate anyway.

The only way to know is to read your actual bill: your unit rate (p/kWh), standing charge (p/day), supplier and whether you're already on a time-of-use plan — then estimate how many kWh you could realistically move.

A note on numbers, and on Northern Ireland

We don't quote a single "typical" smart-tariff rate here on purpose. The Ofgem price cap resets every quarter, and supplier smart-tariff rates change with 30 days' notice — any figure printed in a guide dates fast. As at October 2026, the cap sets a reference point for standard single-rate electricity, but smart and fixed tariffs sit outside it, so your bill is the only reliable source. Confirm the current rate and window directly with the supplier before you switch.

Northern Ireland runs a separate energy market with different suppliers and tariff structures — if you're in NI, the specific tariffs named above may not apply, so check your local options.

How to decide

• Add up your shiftable load: EV miles, hot-water needs, battery capacity, appliance runs.
• Compare your current flat rate against a time-of-use deal's overnight and daytime rates, plus standing charge.
• Model the split: the proportion of kWh you'd move versus what stays on the daytime rate.
• If you have solar, remember your export tariff can come from a different supplier than your import tariff — so you can optimise both separately.

Done honestly, that calculation tells you whether to switch, stay put, or add a controllable load (like an EV charger or battery) first to make a smart tariff worthwhile.

We sell no tariff, take no referral fee from any supplier, and install nothing. Even the "free" comparison sites are paid by whoever they sign you up with — we aren't. Our only job is to tell you whether shifting your load actually pays, or whether you're better off leaving your current tariff exactly where it is.

Figures in this guide are current at the date of publication and indicative only — SEG/export rates change with 30 days' notice, the Ofgem price cap resets quarterly, and grant terms change. Confirm the current numbers for your situation before you commit. This is general information, not personal financial advice.