During a power cut you need an inverter to run the fans, lights and TV. To pick the right VA, first add up what you will run at the same time.
A simple method:
1. Add the watts of all appliances that will run together, for example 4 fans, 6 lights and 1 TV.
2. Divide the total watts by about 0.8. This gives a rough idea of the VA.
3. Add some margin (about 20 percent) so the inverter is not at its limit.
Keep in mind:
1. Heavy appliances like an AC, geyser or heater should not be run on a normal home inverter.
2. How long the backup lasts depends on the battery capacity (Ah), not only on the VA.
3. Tubular batteries usually last longer but need water top-ups.
4. Check the warranty of the battery and the inverter separately.
If you are not sure, confirm the numbers with your dealer too.