Last year, I decided to get a home battery system. According to Octopus Energy, my supplier, I use about 7-13kWh of electricity a day, excluding the electricity used to charge my car.
I am on the Intelligent Octopus Go Tariff. My day-time electricity costs just under 30p/kWh, but between 11:30pm and 5:30pm it drops to just 7.5p/kWh (Intelligent also includes some bonus charging, but let’s ignore that).