What you need to look for when buying an inverter
Summer or winter, power outages can hit you anytime. Don’t find yourself in the dark; instead pick up a handy inverter for your home. In this guide, Conzumr has assembled all the basic information that will help you understand inverter-jargon and ensure that you make an informed choice about which inverter will serve your needs best.
What does an Inverter do?
In simple terms, an inverter is a device that converts DC (direct current) power from an attached battery to AC (alternating current), in order to run appliances in your home or office in case of a power cut.
Inverter or UPS?
A UPS (Uninterrupted Power Service) also converts DC to AC, but the switching over time in such devices is much faster. An inverter, for example, will take at least 100 milli seconds to switch from grid power to battery power, when power fails. This is acceptable in case of basic simple appliances like lights and fans, but if a desktop is connected to the inverter, you will lose data until the backup kicks in. A UPS, on the other hand, takes mere 3-5 milli seconds, thus ensuring critical support and minimum damage to your sensitive electronic devices.
These days home UPSs, which are a combination of inverter and UPS, are also available in the market. So you need not pick up a separate UPS for your electronic devices.
Types of Inverter
There are essentially two technologies that inverters are based on these days.
Pure Sine Wave inverters are ideal if you intend to use the inverter for electronic appliances like TVs and computers because of fast transfer times. Any terminology that says ‘Digital Signal Processing’ or ‘Micro-Controller Based’ means it is a Sine Wave inverter.
Modified Sine Wave or Square Wave inverters have more harmonic distortion than Pure Sine Wave inverters, which is acceptable only if you’re seeking backup for non-sensitive appliances like fans and lights. Modified Sine Wave inverters are less expensive, but also a little outdated.
Your choice, however, will ultimately be determined by your intended usage.
These are the broad specs that you would see on any inverter.
VA (volt-ampere) Rating– This rating determines the load an inverter can take. For example, an inverter may be of 1500VA, 2000VA etc. Later in this guide, we will explain how you can choose the ideal VA rating by calculating your power requirement.
Battery Voltage – The battery determines how long an inverter can run. How long you plan to run your inverter will depend on the duration of power cuts in your area. The unit to measure is V or volts, for example, 12V, 24V, 48V etc. The voltage of your battery must match the specification on the inverter you purchase.
Battery Charging Time – Many models of inverters indicate the time it takes for the accompanying battery to charge completely.
Safety Features– Various safety features like audio alarm, short circuit protection, overload protection, over volt protection and auto reset feature are available and good to have in your inverter.
Warranty– Always check warranty period on the inverter you plan to purchase. You may find it convenient to pick up the inverter and battery of the same brand, so that you only have to call one number for servicing either. Keep in mind though, that regular maintenance is not so much required for inverters, as it is for batteries.
Other Features– Inverters, these days, come equipped with LCD display and indicators that help you monitor available battery, charging time required, over load etc.
Understand Your Power Requirement
In order to zero in on an inverter that works best for your home, you would need to begin by determining your power requirement during an outage.
To know the total load (in watts) that you would need a back-up for, add the wattage of each appliance you plan to use on the inverter. Here is an indicative list for some typical home appliances. You will find more detailed lists online, in case an appliance you plan to use is not listed below.
|60 W light bulb||60 W|
|100 W light bulb||100 W|
|Tube light||40 W|
|Table Fan||25 W|
|Ceiling Fan||50 W|
|CFL||As per indication on cover|
|Desktop Computer||150 W|
|Television (32”)||150 W|
(This list is merely indicative. We suggest you base your final calculations after verifying the power consumption of each appliance you intend to use.)
Let’s say, when you add the wattage of each appliance you plan to use, you get a total of 500 watts.
Now, to get the VA rating of your inverter, we will perform a small calculation. VA is actually the power in watts (as calculated), plus any expected losses. So, you would need to multiply the total watts calculated with a factor called Power Factor (which indicates the efficiency of the equipment).
Watts = VA*Efficiency
If we take 80% as a typical efficiency level,
Watts = VA*0.8
VA = 500/0.8
So for supporting 500 watts, you need an inverter of at least 625 VA.
Things to Note While Calculating Power Requirement:
- If you don’t plan to use all the appliances on your list simultaneously, you can lower the estimate of electricity requirement accordingly.
- If considering big appliances like motors, pumps and compressors (eg fridge, washing machine), don’t just consider their electricity consumption in running state, but the high initial power they consume to get started.
- Some large appliances these days come with special inverter technology. These are designed not to consume a great load of electricity while starting up.
- Inverters come with surge ratings. ‘Surge’ is when an inverter will run on a higher continuous power rating temporarily to start heavy loads. This rating is based on the maximum amperage and time duration that the inverter can run at the higher power level before cutting off or getting damaged. Find out your shortlisted inverter’s surge rating if possible, and accommodate it in your VA calculations.
Types of Batteries
- Lead Acid Batteries require regular maintenance. Electrolyte levels need to be checked and refilled every now and then.
- Tubular Batteries are more expensive, but require lesser maintenance, offer higher efficiency and have longer lives.
- Maintenance Free Batteries are sealed lead acid batteries that, as the name indicate, require little or no care. They are also high in cost and tend to have very little scrap value.
Solar Power Based
You may also choose to opt for an inverter with a Solar Panel Input option. Such inverters will switch to charging the battery from solar energy whenever it is available. Even when electricity is running as usual, if the load is equal to or less than the solar energy available, the load may be operated on solar, thus saving on your electricity bills.
We hope you are now feeling well-informed and raring to start your inverter-purchase spree. If you have determined your budget, you can also look at our articles, Top Five Inverters in India under Rs 5000, Top Five Inverters in India between Rs 5000 and Rs 10000 and Top Five Inverters in India above Rs 10000.
- Article by Piyushi Dhir