Fast read
During a blackout, a properly configured battery system disconnects from the grid and powers your home in island mode. Most systems support essential circuits rather than the entire house. A 10 kWh battery can run key appliances for over 24 hours if usage is controlled. Not all systems include backup by default, so it is important to confirm your configuration.
What Happens in the First Few Seconds of a Blackout?
When the grid fails, a standard solar-only system shuts down immediately due to mandatory safety requirements. This prevents electricity from flowing back into the network and protects utility workers repairing the fault.
A properly configured battery system behaves differently. It automatically disconnects your home from the grid in a fraction of a second, a process known as islanding. Your home effectively becomes its own small power system. The transition is usually very fast, often just a brief flicker of the lights before backup power takes over.
What Will Actually Stay On?
What remains powered depends entirely on how the system was designed. Most Australian homes use partial backup, where only selected essential circuits are connected to the battery.
These typically include:
• Lighting circuits
• Fridge and freezer
• Internet modem
• Selected power outlets
Whole-home backup is possible but requires a much larger and more expensive battery system. For most households, powering essential loads is the practical and cost-effective approach.
How Long Will the Battery Last?
Runtime depends on two factors: battery size and energy usage during the outage. A common 10 kWh battery, if fully charged, can run essential appliances such as refrigeration, lighting and internet for well over 24 hours.
However, high-demand appliances like air conditioning, ovens, electric hot water or pool pumps can drain the same battery in only a few hours. Managing usage during an outage significantly extends backup duration.
If the outage continues into the next day and there is sunlight, modern hybrid systems can recharge the battery from solar panels, allowing the home to remain powered for multiple days under favourable weather conditions.
Are All Battery Systems Automatically Set Up for Backup?
No. Backup functionality is not always included by default. Some systems require additional hardware, wiring and configuration to enable blackout protection.
The switchover is typically very fast but may not be instantaneous enough to prevent sensitive electronics, such as desktop computers, from rebooting. It is not the same as a commercial uninterruptible power supply.
If you already have a battery, confirm with your installer whether backup is enabled and which circuits are covered. Understanding your setup in advance ensures you know exactly what to expect when an outage occurs.
