Does anyone know what time the tariff switch occurs?
It differs depending on where you live, time of year, type of two rate meter you have and who your supplier is. I would ask Bulb customer service as your current supplier. Sorry that is not much more help.
The switching time doesn’t vary by supplier, since it is a fixed configuration of the meter and nothing changes when you switch supplier. This only applies to traditional meters of course, not smart meters.
Best way to know for sure what time the switch occurs is simply to watch which rate register is incrementing around about the time the switch should happen, and see when it changes.
E7 tariff gives you 7 hours at lower ‘night rate’ and 17 hours normal rate. The 7 hours are generally between 2300 and 0800 hrs GMT . They can be split into two periods with a gap, but total will always (should be 7 hours) Ask Bulb what your times are, they may need to check with the meter operator or DNO (distribution network operator)