If you’re reading you electricity costs from an In Home Display they don’t read both peak and off peak tariffs. I’m on Octopus Intelligent Go so 7.5p/kWh from 23:30 – 05:30 and about 28p during the rest of the time. (actualy my tariffs changed today so 7p off peak and 22.41p peak)
My IHD was reading £7 or more after a charge but it was basing it on the wrong price per kW, about 28p instead of 7.5p
It then started reading it the other way round! so while it now reads £2 – £3 for an overnight charge it still reads the peak use during the day at the same rate!. I asked Octopus about resetting or hitting it with a hammer but they said IHD’s are basically useless and not to bother with it!!!
Please excuse spelling/typos. Apart from being a clot it turns out I had one on my cerebellum that's now causing various problems!