How to calculate the size of inverter needed for your home


A lot of people want a power backup or solar system but don’t know how to calculate the energy requirement of their homes. As a side note, you should know that Inverters supply peak /surge power and typical (continuous rating) power. What do these mean? 

ALSO READ: How to calculate the energy consumption of your home 

Appliances such as those with electric motors need high startup surge. This can be referred to as surge power which is the maximum power an inverter can supply for a short time.

When a refrigerator is turned on, the power it ‘pulls’ at first is referred to as SURGE POWER. The power that is supplied on a steady basis afterwards is called CONTINUOUS RATING or typical power.

Moving ahead, let’s calculate the inverter size you need for your home in the following steps:



First, what load do you intend to power? Let’s say 1TV (125W), 8 bulbs (6W each), 2 Fans (65W each), 1 Decoder (25W) and 1 Laptop (85W).

The total power needed will be calculated as “Power = Wattage of appliance x Quantity.” Therefore, you’ll need a total power of (125×1) + (6×8) bulbs + (65×2) fans + (25×1) decoder + (85×1) = 410W. (0.41kW)

Putting into consideration, the power factor of these individual components. Power factor is an expression of energy efficiency. It is usually expressed as a percentage, and the lower the percentage, the less efficient power usage is. Power factor (PF) is the ratio of working power, measured in kilowatts (kW), to apparent power, measured in kilovolt amperes (kVA)

From our example, to get the KVA value, the KW value is multiplied by the power factor value.

(130×0.9) Television + (50×0.9) bulbs + (130×0.9) fans + (30×0.9) decoder + (90×0.9) Laptop = 460W. (0.46kVA)



Now, let’s calculate the inverter’s required capacity, i.e., the Volt-Ampere rating. In an ideal condition, an inverter would operate with 100% efficiency. Most inverters have an efficiency of between 60% and 80%. This efficiency can also be referred to as the power factor of an inverter. For our calculations, we would use a power factor of 0.8. Hence,

The required VA of an inverter is the total wattage of a system divided by power factorPower supplied (or VA rating of the inverter) = Power consumed by equipment in watts / Power factor

Recall, the total power consumed by your home (total wattage) – 460W.
Power factor = 0.8

Therefore, required VA rating of inverter = (460/0.8) = 575VA.

This is approximately a 0.6kVA (600VA).

Using a 0.6kVA inverter will be inappropriate considering surge power and the probability of adding a few small appliances to the system. A 1.0kVA inverter will be suitable for your home. ?

ALSO READ: What is the best type of Inverter for my home?

Are you having any difficulty in calculating the size of inverter needed for your home? Do you have any questions? Please comment or Contact us!

Do you need an inverter/solar system? We are just the solution you need.


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