Economy 7 gives you seven hours of cheaper electricity overnight and charges you more than a normal single rate for the other seventeen. It was designed for storage heaters, which charge up overnight and release heat during the day. Whether it's worth it comes down to one number: how much of your electricity you use in those seven hours.
How Economy 7 works
- Seven cheap hours overnight. Usually about midnight to 7am, but the exact window depends on your region's grid operator and your meter. Some older meters don't change for British Summer Time, so in summer the cheap hours run an hour later by the clock.
- A day rate for the rest. It's higher than the single rate you'd pay on a standard tariff, and that's the catch.
- A two-rate meter. Your meter records day and night use separately. Smart meters can do this too.
Octopus publishes its price-capped Economy 7 rates for every region:
Current rates for Economy 7 on Flexible Octopus, from Octopus's published tariff data: 13.5p–14.7p per kWh at night and 30.7p–33.8p per kWh during the day. The range is across Octopus's 14 regions (direct debit, including VAT), checked 27 September 2026.
For comparison, the same supplier's single-rate tariff:
Current rates for Flexible Octopus, single rate, from Octopus's published tariff data: 25.1p–27.7p per kWh at any time of day. The range is across Octopus's 14 regions (direct debit, including VAT), checked 27 September 2026.
The break-even: about a third of your use at night
Because the day rate is higher than the single rate, Economy 7 only saves money if enough of your use is at night to make up for it. On Octopus's price-capped rates, the break-even was between 32% and 35% of your electricity at night in every one of the 14 regions, both before and after the price cap change on 1 October 2026.
If you have storage heaters or an immersion heater on a night timer, you'll usually clear that easily. If you have gas heating and use electricity mainly in the evening, you probably won't, and a single rate is likely cheaper.
Economy 7 with solar panels
Solar panels generate in daylight, all within Economy 7's day hours. So every kWh of solar you use yourself replaces day-rate electricity, which is worth more than on a single-rate tariff. That makes self-use more valuable, not less.
What changes is the value of diverting surplus solar into hot water. If your immersion heater already runs on the night rate, a kWh of solar sent into the tank only saves you a night-rate kWh. Compare that with your export rate:
Current rates for Outgoing Octopus, from Octopus's published tariff data: 12.0p per kWh exported. The same in all 14 of Octopus's regions, checked 27 September 2026.
With a night rate around 14p, a 12p export rate, and a little heat lost from the tank, diverting and exporting come out close. On a basic export tariff of about 4p, diverting wins clearly. Our diverter vs export comparison works through it, and the diversion method guide explains the rule.
Economy 7 with a home battery
Economy 7 is one of the simplest tariffs for a battery. It charges overnight at the night rate and covers your daytime use at the day rate. Each kWh it moves saves roughly the gap between the two rates, less about 10% lost in charging and discharging. At Octopus's current price-capped rates that's about 15p to 18p per kWh, depending on region. With solar as well, the battery can also store your daytime surplus for the evening. The calculator works out which is worth more for each month.
Storage heaters and heat pumps
Storage heaters are what Economy 7 was built for: they charge in the seven cheap hours and give out heat through the day. Modern high-heat-retention storage heaters hold their charge better than older ones, but they still run almost entirely on the night rate, which is where the savings come from.
Heat pumps fit Economy 7 less well. A heat pump runs through the day, especially in cold weather, and a single overnight window only lets you shift part of that running onto cheap electricity. Tariffs with cheap windows spread through the day, such as Octopus Cosy, let more of it run cheaply.
Checking your own numbers
Look at a recent bill: it shows your day and night units separately. Divide the night units by the total. If it's well above a third, Economy 7 is probably working for you. If it's below, a single rate is probably cheaper, unless you're about to add something that runs at night, such as a battery or storage heaters.
In the calculator, choose Peak and off-peak as your tariff type on the first step, enter your day and night rates, and set how much of your electricity you use at night (from your bill; it starts at 35%). It prices solar self-use against the day rate and battery charging against the night rate, and sizes the battery against the day-rate use it can replace.