The electricity usage of any geyser depends on various factors.
- The geyser’s storage capacity
- The number of people using the water heater
- The rated power of the appliance
- The standing loss depends on the geyser’s star rating and the capacity
This example should explain things better.
A 5-star 15L water heater with a 3Kw rated power can heat the entire tank in 15 minutes. So, if you use the geyser for one hour daily, it should consume three power units. A 15L 5-star geyser has a standing loss factor of around 0.4.
Since you use the appliance for one hour, the appliance consumes around 3.4 units of power (after accounting for the standing loss factor). We presume you do not keep the appliance running for more than an hour daily because every hour it remains idle while remaining connected to the power source, the standing loss is 0.4 units.
Accordingly, you can calculate the monthly and annual power consumption.