How to calculate power ratings and capacity of an Inverter.

In this chapter you would find out how to calculate power ratings and capacity of an inverter. Subsequently we have discussed best inverters, types of inverter and functions of an inverter. The next step is to calculate your power need and decide accordingly the power rating of the inverter you want.

This can be achieved by simply adding the total power of the load which you want to run off the inverter. Below is an example of power ratings of different everyday use equipment that would guide you when making your own calculation.

Fan25 – 80 0.1 – 0.4
washing machine800 – 10004 – 4.5
energy bulb200.01
Music system20 – 400.09 – 0.17
1HP AC1000 – 15004.3 – 6.5

When you have taken down every detail like the table above, you then sum them up. To find your inverter capacity, you would need to divide the total power rating by the power factor. What you get should be the range of your inverter capacity.

The next line of action would be to calculate the capacity of your battery. You can achieve that by applying the following formular:

If you know the watts instead of the amps, follow the following procedure:

Convert watts to amps. Actually, watt is the fundamental unit of power and watt-hour is the energy stored. The key is to use the watts you know to calculate the battery voltage.

For example, say you want to run 250watt 110VAC television from an inverter for 5 hours.

watt-hours = watts x hours = 250w x 5hours = 1250watts-hours

where efficiency of the inverter is 85%

Therefore, watts-hours = watts x hours / efficiency = 1250 / 0.85 = 1470 watt-hours.

Since watt = amps x volts, divide the watt hour by the voltage of the battery to get the battery to get amp-hours of the battery storage.

So amp-hours (at 12volts) = watt-hours / 12volts = 1470 / 12 = 122.5AH

Since you have learnt how to calculate power ratings and capacity of an Inverter. You are free to go and choose the inverter, whose values and ratings are the nearest to your required values.

So I hope now selecting the right type of inverter is an easy task and will help you make the right choice. So keep visiting us for some more information and guidance, as we I will be moving to Inverter batteries next.