Electricity Used in Heating Water and Replacing by Solar
Heating water using an electrical resistance element is extraordinarily energy intensive.
The graph below shows how much electricity is consumed heating water per person per day based on the number of minutes they spend in the shower
Kwh's Used in Heating Water with Electric Geyser
Although showering is more efficient from both an electrical and water saving perspective many people (particularly ladies) prefer to bath.
A full bath at 40 C will typically be between 150 litres and 180 litres, using over 4kWh in electricity.
|Volume||1 Person||2 Person||3 Person||4 Person||5 Person||6 Person|
|130 litres per person per day||3.61||7.22||10.83||14.44||18.06||21.67|
|150 litres per person per day||4.17||8.33||12.50||16.67||20.83||25.00|
|200 litres per person per day||5.56||11.11||16.67||22.22||27.78||33.33|
When going solar not only does the solar system and tank need to heat the water used in the shower or bath, it needs to be of sufficient size to cater for the next morning as well.
As a general rule, size does matter, bigger is better, as long as the power of the solar system is adequate to heat the volume of water.