Tariffs like Octopus Go give you cheap overnight electricity at 7–8.5p/kWh, but your peak rate goes up. Whether you save depends on how much usage you can shift — EV charging, battery cycling, smart appliance timers. This calculator models your actual load-shifting potential.
Without any load-shifting, roughly 15% of a household's usage naturally falls in the off-peak window (00:30–05:30 on Go). That's not enough to overcome the higher peak rate — you'd actually pay more.
With an EV, you shift an additional ~20% of your total usage (all overnight charging). With a battery, another ~25% shifts. Smart appliance timers add a further ~8%.
Stack them all and you can shift 60–70% of your usage to off-peak — at which point Go saves £300–£600 a year versus a flat rate, even accounting for the higher peak price.
Real-world shifting depends on your household pattern. These percentages are estimates based on typical UK usage profiles.
Night shift workers who are home during the day and asleep at night can't take advantage of off-peak windows.
Low-usage households (under 2,500 kWh/yr) save smaller absolute amounts — sometimes under £100/year, which may not be worth the hassle of managing timers.
Standing charge differences sometimes wipe out unit-rate savings — always check the standing charge, not just the headline rate.
Octopus Go's peak rate is higher than the cap (currently 27.5p vs 24.5p). If you can't shift much usage, you'll pay more.