Seven questions to ask before you buy a UPS or battery backup

Two quotes for "5 kW backup" can differ by a lot and still be for very different systems. These questions put them on the same footing.

1. Which make and model, exactly? A quote that says "sodium-ion UPS" without a model cannot be compared with anything.
2. What is the usable capacity in kWh? Rated and usable can differ. Hours of backup come from usable energy.
3. What is the surge rating, and for how long? Motors start with a burst. Ask what the inverter allows and for how many seconds.
4. What exactly does the warranty cover? Years, cycles or energy throughput, what counts as failure, and who collects the unit.
5. What loads are on the backed-up circuit? A list, in writing. It stops the geyser being added later and flattening the battery.
6. What happens at the changeover? How quickly it switches and whether your equipment will ride through it.
7. Who looks after it afterwards? A name and a phone number, and what a service visit includes.

We put the answers to all seven in the quote before you ask. Request one.