Will a solar battery power my home during a blackout?

It can, but only if the system is designed and configured for backup. Most grid-connected solar-only systems shut down during a blackout for network-worker safety. A battery also does not provide backup automatically: the design needs compatible equipment, isolation, suitable controls and a clearly defined backup scope.

Feature, advantage, benefit and limitation

• Backup gateway or islanding equipment. This safely disconnects the backup system from the grid during an outage. The advantage is that nominated loads can keep operating. It must be compatible with the complete system and installed correctly.
• Selected essential circuits. Lighting, refrigeration, communications or water pumping can be prioritised instead of trying to supply every appliance. This can make available battery capacity last longer. It also means non-backed-up circuits will remain off.
• An islandable solar-and-battery design. Some systems can continue using solar and recharging the battery while isolated from the grid. This may extend useful backup in daylight. Output, weather, battery state of charge and equipment limits still apply.
• Stated battery capacity and power output. Capacity affects how long loads can run; power output limits what can run at the same time. A large energy capacity does not mean every high-power appliance can start or operate together.

Questions to answer before requesting a design

Which appliances genuinely need to operate? What are their starting and running loads? Does the property use single- or three-phase power? Do you need short outage coverage or resilience over multiple days? Should solar recharge the battery while the grid is down? Ask the supplier to list every backed-up circuit, usable capacity, continuous and surge output, changeover behaviour and important limitations in the written offer.

The Australian Government battery guide explains that few solar-only systems provide blackout power and that batteries must be configured for backup. It also distinguishes battery capacity from power output and notes that backup may cover the whole property, selected circuits or only one phase.