Where is everybody?

[Vasudev]

It is connected to lead acid battery for backup power and electricity is from local grid. The inverter is a smart inverter which can function as inverter and pure sine wave UPS.

Just one car battery? Have you checked how many watts it puts out when fully charged, or its capacity in kWh? It couldn't be that much. What do you run with it?

I assume you have an A/C powered charger for when power returns.

You're an engineer. Is it possible to buy 2 or 3 and run them as an array? Lead acid batteries are relatively cheap when compared to other technologies.

As for the inverter, as you know if you're running an electric motor you've go to go with pure sinewave. With a solid state device it doesn't really matter. The A/C input has to be converted back to DC for it to work.

Yes, there's AC power charger.
It can be run as an array. For now, we conservatively use the stored energy since powercuts are very frequent and longer sometimes.