Home batteries and blackout backup: what you need to know

A surprising number of home batteries shut down in a blackout along with the grid, because keeping a battery running safely when the grid is down needs extra hardware that isolates your home from the network, so line workers are not put at risk. Without that hardware, the battery sits idle during the very event you bought it for.

Backup also comes in degrees. Whole-home backup keeps everything running within the battery's limits; partial or essential-circuit backup keeps a chosen set of circuits alive, such as the fridge, lights and internet. Which one you get depends on the battery, the extra hardware and how it is wired.

A battery sized to trim your bill is not automatically sized to run your home through an outage.

• Backup capability: confirm the battery supports it, and whether it needs a backup gateway or similar hardware.
• Whole-home vs essential circuits: decide what you actually need running, since whole-home backup costs more.
• Usable capacity for an outage: enough to cover your essential load for the length of blackout you want to ride through.
• Recharge during an outage: whether your solar can recharge the battery while the grid is down, which extends how long backup lasts.

Because backup adds hardware and changes the wiring, it is something to raise with your installer at the quote stage rather than assume. A good installer will tell you honestly whether whole-home backup is practical for your switchboard or whether essential-circuit backup is the sensible option, and what each costs.

Apollo Energy Group is a NSW-based, SAA-accredited installer (Electrical Licence 400672) that sizes systems from your real usage and can specify backup as part of the quote. Refer Labs readers get $500 off through our link, on top of the federal rebate. Confirm exactly what backup you are getting, and what it covers, in writing.