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Calculation: Appliance Watts × Hours used per day = daily watt hours consumption
|Electric Blanket (double)||100||200|
Hair curler or straightener
Mobile Phone charger
|Portable electric fan||10||50|
Portable electric heater
Water Pressure Pump (shower)
Water Pressure Pump (sink only)
When we are calculating what size solar power system to install in a caravan/RV we consider how many watts your appliances use and how long you use them for.
If you have already read our power v energy pageyou will know that a watt (W) is a measure of how much electrical energy is being used. 1000W equals one kilowatt (kW).
A Watt hour (Wh) represent the estimated amount of energy an electrical appliance consumes in one hour.
To work out the Wh take the watts (W) of the appliance and multiply this with the hours used on the average day.
This will give you the Wh consumed in your caravan/RV per day.
An appliance usually has the wattage it uses written on the label. This label is often at the back or bottom of the appliance. The list below shows some common appliances used in caravans and RVs and the typical watts they use.
How much electricity do the appliances in your caravan/RV use?
Red circle indicates watts displayed on label underneath toaster
Some items are used only for a fraction of an hour or minute per day, for example a kettle. The calculation for this scenario is:
Watts × minutes used per day ÷ 60 minutes = daily watt hours (Wh)
A 1100 watt kettle used for 10 minute per day will therefore only consume 183 watt hours per day or 0.18 kWh:
1100W x 10 ÷ 60 = 183.3 Wh
This is relevant if you have a compressor fridge in your caravan/RV (rather than a 3way fridge)
Even though a fridge is “turned on" all the time, the actually cycle goes on and off as needed to maintain its temperature. This is dependent on how hot a day it is. Nevertheless, to estimate the number of hours that a refrigerator actually operates at its maximum wattage you can divide the total time the refrigerator is plugged in by three to give you an average estimate.
For a typical caravan/RV fridge let’s do the calculation:
80 watts ÷ 3 = 27 watts
27 watts x 24 hours = 648 Wh
If you use a portable fan that uses 20 watts for 4 hours per day then the calculation is:
20W x 4 hours = 80 daily watt hours (Wh) consumption
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