Inverter or Generator for Home: The Arithmetic Nobody Does Before Buying

Before comparing any product, write down two numbers: the average daily outage duration in your area, and whether that outage is predictable or random. These two facts alone split most households into their correct category before price enters the conversation.

An inverter with a lead-acid battery is designed for gaps of two to six hours. It charges during supply, stores enough to run lights, fans, a router, and a television, then recharges when power returns. If your colony has scheduled cuts of three to four hours a day, an inverter is almost certainly the right answer. It runs silently, requires no fuel, and the running cost after purchase is close to zero except for the electricity used to charge it.


A generator becomes the correct answer when outages are long, unpredictable, or both, eight hours or more, or cuts that arrive without warning and stretch through the night. It produces power as long as petrol or diesel is in the tank. It does not need grid supply to recharge. For areas with genuinely poor grid infrastructure, particularly in smaller towns and rural districts, this is not a luxury choice; it is the only one that works.


Every inverter and generator is rated in VA or watts. Most buyers pick a number that sounds safe and overpay. The calculation takes ten minutes.


List every appliance you intend to run during a cut. For each, note the wattage from the back panel or the manual. A ceiling fan runs at roughly 70 to 75 watts. A tube light or LED batten is 20 to 36 watts. A desktop router is 10 to 15 watts. A 32-inch LED television is 40 to 60 watts. A refrigerator compressor draws between 150 and 200 watts when the compressor kicks in, though its average consumption is lower.

Add those numbers. That is your load in watts. Divide by 0.8 to get the VA rating you need, because most inverters operate at a power factor of 0.8. If your load totals 600 watts, you need a 750 VA inverter at minimum; a 900 VA unit gives you headroom.

Now the critical question most buyers skip: what is the battery capacity you actually need? A 150 Ah tubular battery paired with a 900 VA inverter gives roughly six to seven hours of backup at a 300-watt load. At 600 watts, that drops to three hours. The battery is not an afterthought. It is half the system and, over ten years, the more expensive half.

A 1 kVA inverter with a 150 Ah tubular battery costs somewhere between ₹18,000 and ₹25,000 installed, depending on brand and city. That looks cheap against a 2 kVA generator at ₹30,000 to ₹45,000. But the inverter battery needs replacement every three to five years. A tubular battery replacement costs ₹12,000 to ₹18,000. Add that in and the five-year cost of the inverter system is ₹30,000 to ₹43,000.

Now run the generator numbers. A 2 kVA petrol generator consumes roughly 0.8 to 1 litre of petrol per hour at half load. If you run it four hours a day for ten months of the year, the rough outage season across most of north and central India, that is around 1,200 litres over five years. At current petrol prices, that is ₹1,08,000 in fuel alone, before oil changes, servicing, and spark plug replacements. The generator that looked expensive at ₹40,000 costs ₹1.5 lakh over five years.

This arithmetic does not mean generators are wrong. It means they are expensive to run and should only be bought when the inverter genuinely cannot do the job. If your outages are four hours or less and predictable, the generator math rarely works in your favour.

Inverter salesmen tend to undersell battery capacity. A 600 VA inverter with a 100 Ah battery is cheaper to sell; it also runs out in ninety minutes under real household load. Ask for the backup hours in writing at your actual load, not the theoretical maximum the spec sheet quotes.

Generator salesmen tend to understate fuel consumption. The figure quoted is usually at rated load. Most home generators run at 40 to 60 percent of rated load, where efficiency is lower and consumption per unit of output is higher than the brochure implies. Ask for the consumption figure at half load, which is the number that matches how you will actually use it.

There is a third option that has become genuinely viable in the last few years: a lithium iron phosphate battery paired with a hybrid inverter. The battery lasts eight to twelve years, charges faster, handles deeper discharge without damage, and takes up less space. The upfront cost is higher, ₹40,000 to ₹80,000 depending on capacity, but the five-year cost of ownership, with no mid-cycle battery replacement, is often lower than a tubular lead-acid system. If your outages are moderate and you plan to stay in the same home for a decade, the lithium option deserves a column in your calculation.

Outage under four hours daily, predictable, urban grid: inverter with tubular battery, 150 Ah minimum. Outage four to eight hours, mixed predictability: inverter with 200 Ah battery or lithium hybrid. Outage over eight hours, or genuinely unpredictable grid with no supply for long stretches: generator, diesel preferred over petrol for running cost, with the five-year fuel budget written down before you buy. Outage moderate but you want a long-horizon solution with minimal maintenance: lithium hybrid inverter.

Chanakya wrote in the Arthashastra that a resource poorly matched to its purpose wastes both the resource and the purpose. The inverter sitting in a house with twelve-hour cuts, dead by 10 pm every night, is that waste made concrete. So is the generator idling through a three-hour scheduled cut, burning ₹200 of petrol to run two fans and a router that a ₹20,000 inverter would have handled on stored charge.