What size inverter for a 1 HP water pump?
Filling the overhead tank during a cut. A pump motor starts at several times its running watts.
- 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 |
|---|---|---|---|
| Water pump (1 HP) motor | 1 | 750 W | 750 W |
| LED bulb | 2 | 9 W | 18 W |
| Running load | 768 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 | 2 × 120 Ah tubular | 1500 VA, 24 V | 1 × 25.6 V 100 Ah lithium |
| 4 hours | 2 × 200 Ah tubular | 1500 VA, 24 V | 2 × 25.6 V 100 Ah lithium |
| 6 hours | 2 × 260 Ah tubular | 1500 VA, 24 V | 3 × 25.6 V 100 Ah lithium |
| 8 hours | 3 × 230 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 | 36 units | 9.1 units | 45.1 units a month |
| 2 h | 72 units | 9.1 units | 81.1 units a month |
| 4 h | 144 units | 9.1 units | 153.1 units a month |
Inverters in our list that fit
From the makers’ stated ratings, smallest first. Brands are not ranked.
| Model | Rating | Battery | Wave |
|---|---|---|---|
| Livguard LGS1600 | 1500 VA | 12 V | Pure sine wave |
| Livguard LGS1700 | 1500 VA | 24 V | Pure sine wave |
| Luminous Eco Volt Neo 1650 | 1500 VA / 1260 W | 24 V | Pure sine wave |
| Luminous Zelio+ 1700 | 1500 VA / 1260 W | 24 V | Pure sine wave |
| V-Guard Jaadoo 1650 | 1500 VA / 1260 W | 24 V | Modified (pseudo) sine wave |
| V-Guard Synergy Smart 1800 | 1550 VA / 1350 W | 24 V | Pure sine wave |
| Microtek vTURBO NEW 2000 | 1650 VA / 1320 W | 24 V | Pure sine wave |
| Microtek Solar PCU 2035 | 1735 VA / 1300 W | 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.