Elevator Backup Power using Growatt Hybrid inverter

This is in Europe, so everything is 230vac.

In our apartment block we have a 5-stop, 4 person elevator which runs off a 3-phase supply. It is based on a gearless synchronous AC motor driven by a controller rated at 5.5kW. During operation, I measured the consumption to be around 1kW per phase. This elevator doesn’t do any regen and dumps braking power to a dedicated resistor.

The grid power source is relatively stable in terms of voltages, but we often have brownouts and blackouts in our area, so we need to install some form of battery backup. Initially I thought about a 10kVa datacentre online UPS, but these come with multiples of 9Ah bricks which take up a lot of space and have very little runtime, and we can’t easily add solar later.

So instead I’m thinking about installing a Growatt SPF 5000 ES paired with a couple of Pylontech US3000C.

What I like most about these units:

• AC input and output. I could hook the grid straight into the input and the elevator to the output, no need for separate isolation contactors and complexity.
• I can add PV panels in the future very easily
• If 5kW isn’t enough due to inrush currents, I can always add another unit (or 3 or 4) and parallel them up
• 10ms switchover time between grid supply and battery supply – seamless for the elevator
• Dirt cheap for what they offer

Questions:

1. Would you do it this way? Is there anything I’m missing?
2. Would you pair it up with the Pylontech batteries or is there a better alternative?
3. Thoughts on running a large inductive load such as this on a high frequency inverter?