Want to Buy a Small Inverter? Keep These Important Factors in Mind


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In India, one of the biggest problems that people face during the summer season is power cuts. The worst-hit are those who live in Tier 2 and Tier 3 cities where there are frequent and long power cuts. In a scenario like this, the only way to tackle this is to bring home a small inverter that can provide the required power back-up to run the basic home appliances such as fans, tube lights, bulbs, TV, refrigerator, etc.

For those, who want to run heavy loads like AC, microwave, washing machine, there are heavy capacity inverters, too, available in the market. So if you too are facing power cuts in your area and are planning to buy a small inverter for your home, here is a list of factors that one should take into account. Let’s take a look.

There are two main components of a small inverter – the inverter and the battery. Here are tips to help you make the right choice!

Choosing the Right Small Inverter

To choose the right inverter you need to consider

  1. VA Rating of the inverter
  2. Inverter Technology

What is VA Rating and how is it calculated?

VA Rating of an inverter is the voltage and current it can supply. It is measured in VA (Volt Ampere). To find out what is the right VA Rating of the inverter you should buy, you need to know your power requirement.

Here’s how to calculate your power requirement

Calculating your power requirement is very easy. All you have to do is make a list of equipment that you would require when there’s a power cut. Let’s say you require 3 Fans, 2 Tube Lights, 8 LEDs, 1 LED TV. And let’s say the power consumed by each is as follows.

  • 1 Fan – 70 Watts
  • 1 Tube light – 40 watts
  • 1 LED light – 7 watts
  • 1 LED television – 70 watts

On multiplying each of these with the number of appliances required, we will get the total power required. 

Total Power Requirement = (3*70)+(2*40)+(8*7)+(1*70)+(1*140)= 556 Watts

Formula for VA Rating

VA Rating = Load Requirement / Power Factor of the Inverter

(Note – Usually, the Power Factor lies between 0.65-0.8. We will assume it to be 0.7 in this case).

So for a household with 556 Watts of power requirement, 

One should buy an inverter with the following VA Rating = 556/0.7 = 795 VA (rounded off)

But we recommend you to go with an inverter with a 10-20% higher VA Rating which means in this case you buy an inverter with a VA Rating of 900 VA.

Note – Always buy an inverter with a higher VA rating. That’s because your power requirement may increase with time, and therefore, an inverter with a higher VA Rating will be able to cope with that increase in power requirement. Typically, buying an inverter with a 10-20% VA rating should suffice.

Inverter Technology

The next factor you need to consider is Inverter technology. Home UPS inverters are available in two technologies

  • Sine Wave
  • Square Wave

Difference between a Sine Wave Inverter and a Square Wave Inverter

As we know the primary function of an inverter is to convert DC (Direct Current) to AC (Alternating Current). Higher the conversion efficiency, better the inverter.

Current Conversion Efficiency

A Sine Wave Inverter is more efficient as compared to a Square Wave inverter as it has a higher conversion efficiency. The square wave, on the other hand, does not produce Alternating Current as pure as the current produced by Sine Wave inverters Another drawback with square wave inverters is that the devices when to run on square wave technology, get heated up and produce a humming noise.

Device Safety

In terms of appliance safety, Sine Wave technology again has an edge over square wave technology. It is safer to run appliances that are connected to sine wave inverter technology.  It is therefore recommended that one should run devices like refrigerators, microwaves, laptops, etc on sine wave. The square wave technology is more suited for running devices like motors.


Inverters with square wave technology are comparatively cheaper as compared to inverters with sine wave technology. And that’s rightly so, as inverters with sine wave technology are more efficient. Also, we would recommend you not to choose an inverter based on its price. Rather, choose an inverter based on your requirement. 

Choosing the Right Inverter Battery

To choose the right small inverter battery you need to consider

  1. Battery Capacity
  2. Battery Type

What is Battery Capacity and how is it calculated?

The unit of battery capacity is Ampere Hours and it is a measure of the charge a battery can hold. Usually, the inverter batteries used in a residential setup range anywhere between 60 Ah – 220 Ah.

Formula for battery capacity

Battery capacity = (power requirement in watts * backup-time * aging factor) / (battery voltage * battery efficiency * inverter efficiency)

As calculated in the previous example Power Requirement = 556 watts

The following values are constant

  • Inverter aging factor=1.25
  • Battery efficiency=0.8
  • Inverter efficiency = 0.8

And let us assume

  • Back up hours = 2 hrs
  • BAttery voltage = 12 V (As battery voltage for lead acid battery = 12 V)

To reach the final value of battery capacity, insert values in the above mentioned formula

Battery capacity = ((556*2*1.25) / (12*0.8*0.8) = 181 Ah

Note – Just like it is advisable to go for an inverter with a higher VA Rating, similarly it is advisable to go with a higher capacity. So, in this scenario where the calculated battery capacity is 181 Ah, you can go with a battery with a battery capacity of around 200 Ah.

Types of Battery for Small Inverter

There are two main types of batteries – Flat Plate and Tubular Battery.

Flat Plate Battery

A flat plate battery is a good option for those who are looking to buy a battery that’s light on the pocket. It is a type of lead-acid battery. Flat plate batteries have a faster rate of charging and are therefore recommended for areas that experience frequent power cuts. However, they are not suited for areas that undergo longer durations of continuous power cuts because flat plate batteries have low battery capacities.

Tubular Battery

Tubular batteries, too, are a type of lead acid battery. They are more efficient and can hold more charge as compared to flat plate batteries, and are therefore more expensive. There are two types of tubular batteries – short tubular and long tubular.

Long tubular batteries have a higher battery capacity as compared to short tubular batteries. Tubular batteries are best suited for areas that experience long power cuts. If you are looking for a battery with a high battery capacity, minimal maintenance, and a longer life expectancy, you should go with a tubular battery.

Want to buy a small inverter?

If you are looking to buy a small inverter we recommend you to check out the wide range of inverter battery combos that Luminous has to offer. You can also go to their official website and use their Load calculator to determine the right VA Rating and Battery capacity for your small inverter.

Sushant Gupta
Sushant Gupta
More than just Gadgets and Gaming enthusiast, a die-hard techy, interested in anything tech be it PCs, gaming consoles, gadgets, sports, just pop it up. Bottom line is I am a technology purist at heart


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