What size inverter for a 3 BHK home?
Four fans, nine LED lights, the TV, Wi-Fi, the fridge and a laptop.
- Typical appliance watts, change them in the calculator
- Indian inverter sizes
- Tubular or lithium
The load
Typical ratings. Check the plate on your own appliances; a BLDC fan uses about 30 W instead of 75 W.
| Appliance | How many | Watts each | Total |
|---|---|---|---|
| Ceiling fan | 4 | 75 W | 300 W |
| LED bulb | 9 | 9 W | 81 W |
| Television | 1 | 80 W | 80 W |
| Wi-Fi router | 1 | 10 W | 10 W |
| Refrigerator motor | 1 | 150 W | 150 W |
| Laptop | 1 | 50 W | 50 W |
| Running load | 671 W |
Battery for the backup you want
Tubular: 12 V batteries, the usual choice. Longer backup moves you to a 24 V inverter with two batteries. Lithium: LiFePO4 modules.
| Backup | Tubular battery | Inverter for that | Lithium |
|---|---|---|---|
| 2 hours | 1 × 220 Ah tubular | 1050 VA, 12 V | 2 × 12.8 V 100 Ah lithium |
| 4 hours | 2 × 165 Ah tubular | 1500 VA, 24 V | 4 × 12.8 V 100 Ah lithium |
| 6 hours | 2 × 230 Ah tubular | 1500 VA, 24 V | 3 × 25.6 V 100 Ah lithium |
| 8 hours | 3 × 200 Ah tubular | 3200 VA, 36 V | 4 × 25.6 V 100 Ah lithium |
What it adds to your bill
| Power cuts a day | Recharging | Standby | Adds to your bill |
|---|---|---|---|
| 1 h | 31.5 units | 6 units | 37.5 units a month |
| 2 h | 62.9 units | 6 units | 69 units a month |
| 4 h | 125.8 units | 6 units | 131.9 units a month |
Inverters in our list that fit
From the makers’ stated ratings, smallest first. Brands are not ranked.
| Model | Rating | Battery | Wave |
|---|---|---|---|
| Exide STAR 12V 1050VA | 1050 VA | 12 V | Pure sine wave |
| Exide GQP 12V 1050VA | 1050 VA | 12 V | Pure sine wave |
| Luminous Zelio M 1300 | 1100 VA / 924 W | 12 V | Pure sine wave |
| Luminous Zelio S 1250 | 1100 VA / 926 W | 12 V | Pure sine wave |
| Luminous Optimus 1250+ | 1100 VA / 924 W | 12 V | Pure sine wave |
| Luminous Eco Volt Neo 1250+ | 1100 VA / 924 W | 12 V | Pure sine wave |
| Microtek vTURBO NEW 1400 | 1150 VA / 925 W | 12 V | Pure sine wave |
| Microtek vTURBO NEW 1550 | 1250 VA / 1000 W | 12 V | Pure sine wave |
| Amaron HB1550A | 1400 VA | 24 V | Pure sine wave |
| Luminous Eco Volt Neo 1550 | 1400 VA / 1176 W | 12 V | Pure sine wave |
| Exide STAR 24V 1450VA | 1450 VA | 24 V | Pure sine wave |
| Exide GQP 24V 1450VA | 1450 VA | 24 V | Pure sine wave |
Questions
How is the inverter size worked out?
Running watts × 1.25 for a safety margin ÷ 0.8, the power factor Indian brands rate their inverters at. Then we pick the next standard size. Motors such as a fridge or pump also need starting surge, which we check against the inverter’s rating.
Why do the hours change the battery but not the inverter?
The inverter sets how much can run at once; the battery sets for how long. Longer backup needs more Ah, and past what one 12 V battery can give, a 24 V inverter with two batteries.
Will this raise my electricity bill?
Yes, a little. The battery is recharged from the grid after every cut, with some loss, and the inverter draws standby power all day. Each page shows the units a month; the calculator prices them at your state’s slabs.