Octopus Energy - Worth Changing

Ildhund

la531983 said:
Economy 7 is generally only really worth doing if you can shift at least 40% of usage to night
... possible on some tariffs you can get away with as low as 35%

If you can identify two comparable tariffs for the same supply, one single-rate and the other dual-rate, then this is a rule of thumb: dual-rate will be cheaper if night usage is more than 

• [Day rate ‒ Night rate] / [Day rate ‒ Single rate]

of the total usage. This doesn't take account of any difference in standing charges, which are often similar in the two cases. 

The 40% figure was once a standard. Ofgem mandated that a dual-rate tariff for prepayment customers would be compliant if it would lead to lower bills if the offpeak usage was more than 42% of the total. In my experience, suppliers have been much more generous in the past couple of years.