How to buy Inverter?

Overview

Many people are often confused whence buying an inverter. To answer some queries and make you more aware of inverters, here we have assembled all the basic information and inverter-jargons that will help you choose an inverter according to your needs.

What are Inverters?

An inverter is a device that converts DC (direct current) into in AC (alternating current) in the case of power cuts and allows you to use electrical appliances. These are powered by chemical batteries, wind turbines or solar panels.

How do Inverters differ from UPS?

A UPS (Uninterrupted Power Service), provides backup during a power outage. It also converts DC into AC, but switching time is instantaneous. An inverter will take about 100 milliseconds to switch from grid to battery power. This works for appliances like a fan, tube lights, etc. but can be critical if a desktop is connected to the inverter, then data may be lost until backup kicks in. Whereas, a UPS starts within 3-5 milliseconds, preventing any critical damage and impressive support to your sensitive electronics. Nowadays in the market, home UPSs which are a combination of UPS and inverter are available. So you do not need to buy separate UPS for your electronic machines.

Types of Inverters

Inverters are essentially based on two technologies.

1. Pure Sine Wave Inverters – These are an ideal choice if you intend to use the inverter for your electronic devices like computers and TVs. Any mentions of ‘Micro-Controller Based’ or ‘Digital Signal Processing’ means it is a Sine Wave Inverter.
2. Modified Sine Wave or Square-Sine Wave – They have more harmonic disruptions than Pure Sine Wave inverters. They are efficient if you want to use them for your non-sensitive appliances such as fans, tube lights. They are quite cheaper and popular, but a little outdated as well.

Understand your power requirement

To finalize as to which Inverter will be best for your home, you need to start with estimating your power requirement during a power outage.

Calculate the total load in watts that needs back-up, add the wattage of each appliance that you would like to use even when powered by the inverter. Below is the list of appliances that are typically used on inverters.

This is just an approximate list. You should base your final calculation after verifying the consumption of respective appliances.

To assume, your total wattage comes to about 500 watts.

How to find out your VA rating

VA rating stands for Volt-ampere rating. It is, basically, voltage and current supplied by an inverter to the appliances. VA is power in watts, plus any expected losses. For this, you need to multiply the calculated watts with a factor called Power Factor, it indicates the efficiency of the equipment.

Watts = VA x Efficiency

As no inverter gives 100% efficiency even under ideal situations, it is around 60-80%

Watts = VA x 0.8

VA = 500/0.8

So for supporting 500 watts, you require an inverter of a minimum of 625 VA.

Things to consider while calculating power requirement

• Do not add up the wattage of those appliances which you do not plan on using.
• While considering heavy appliances like pumps, motors or compressors (refrigerators), do not cogitate their energy consumption in running state, but add the initial high power they require to get started.
• These days few large appliances come with special inverter technology, which is designed not to take up too much load of electricity while starting up.
• Inverters come with ‘Surge’ rating, it is when an inverter runs on a high continuous power rating, temporarily, to start heavy loads. This rating is based on the time duration and maximum amperage that the inverter can function at the high power levels before cutting off or getting damaged. We suggest you find out your shortlisted inverter’s surge rating if possible and measure to see if it’s suitable for your VA calculations.

Types of batteries

1. Lead Acid Batteries – These require regular maintenance. Electrolyte level needs to be kept under the tab and refilled quite often.
2. Tubular Batteries – They require less maintenance, highly efficient and have longer lives. Hence, quite on the expensive side.
3. Maintenance Free Batteries – As the name suggests, they have sealed lead-acid batteries, require little or no maintenance. These are also quite expensive and have no scrap value.

Solar power based

You can also opt for of inverters with the Solar Panel input option. These inverters switch to solar energy, whenever available. Even if the electricity is running properly, and the load is less or equal to the solar energy available, it may get switched to solar and thus saving on electricity power consumption.

Specifications to look on for

1. Battery Voltage – The battery of inverter depends on how long you want it to run. How long it can run, in return, depends on the duration of power cuts in your area. The unit of measurement is volts or V, e.g. 12V, 24V, 48V etc. The voltage of the battery must match with the inverter’s specifications you want to buy.
2. Battery Charging Time – Check how long it takes for the battery to charge 100%
3. Safety Features – Many safety features such as short circuit protection, audio alarm, overvolt protection, overload protection, and auto reset features are good to have in your inverter.
4. Warranty – Always check for the warranty on the inverter you plan on purchasing. You can conveniently buy inverter and battery of the same brand, so for servicing of either, you need to call on one number. Batteries require more regular maintenance compared to inverters.
5. Other Features – New age inverters come with LCD display and indicators that enable you to monitor charging time require, available battery, overload, etc.