Blackout backup planning · Brisbane & SEQ
Choose what stays on before choosing how much battery to buy.
Blackout backup is an engineered operating mode, not a feature guaranteed by battery capacity alone. Start with the circuits and appliances your family actually needs when South East Queensland summer storms hit the grid.
Capacity versus power
kWh tells you how long. kW tells you how much at once.
Stored energy · kWh
Battery capacity (kilowatt-hours) dictates runtime. A 20kWh or 28kWh battery stores enough energy to sustain household baseload across multiple days of an outage, but it does not determine how many heavy appliances can start simultaneously.
Backup output · kW
The inverter continuous EPS output and battery discharge rate (kilowatts) set the ceiling on instantaneous demand. Induction cooktops, heat pumps and air conditioning compressors require high peak starting currents that must fit within the inverter's surge envelope.
Define the backup scope
Three practical levels of Brisbane blackout protection.
1 · Essential circuits (Single-Phase)
Covers family necessities: refrigerator, freezer, Wi-Fi router, LED lighting circuits, home office power and phone charging. Typically draws 500W to 1,200W, easily supported by a standard 5kW hybrid inverter.
2 · Extended comfort (Single/Three-Phase)
Adds a single energy-efficient split-system air conditioner, microwave, garage door opener and television. Requires a 5kW–8kW EPS output and careful power management during peak summer heatwaves.
3 · Whole-home backup (Three-Phase)
Powers the entire switchboard including ducted air conditioning, electric cooking and water heating via a 10kW to 15kW three-phase hybrid inverter (such as the FoxESS H3 series) with high-capacity modular storage.
Multi-day resilience
Can rooftop solar recharge your battery while the grid is down?
During severe weather events in South East Queensland, network outages can last from several hours to multiple days. In an unoptimised system, a battery that runs flat on night one remains empty until the grid returns.
With an integrated FoxESS hybrid system featuring black-start capability, the inverter establishes its own reference voltage and frequency (50Hz AC). As soon as sunlight strikes your rooftop panels the next morning:
- Rooftop solar begins generating electricity directly in island mode.
- Daytime household loads (refrigeration, cooling, appliances) are powered directly by solar.
- Surplus daytime generation recharges the battery modules back to 100% before sunset.
- The home enters the subsequent evening fully charged, enabling multi-day off-grid independence.
Estimated runtime
How long different battery capacities last during an outage.
Essential baseload (~600W average)
Fridge, freezer, Wi-Fi, LED lights, device charging:
- 20.72kWh battery: 28 to 32 hours runtime
- 28.56kWh battery: 38 to 44 hours runtime
- 41.44kWh battery: 55 to 64 hours runtime
- With daylight solar: Runs indefinitely
Comfort load (~2,000W average)
Essentials + split-system aircon + microwave / TV:
- 20.72kWh battery: 9 to 11 hours runtime
- 28.56kWh battery: 12 to 14 hours runtime
- 41.44kWh battery: 18 to 20 hours runtime
- Requires matching inverter continuous kW output
Plan your backup scope with local electrical installers.
Tell us which appliances must stay on and send a photo of your switchboard. We will design a compliant backup arrangement tailored to your property.
Switchboard & electrical standards
What happens inside the switchboard during blackout installation.
Australian Standards AS/NZS 4777.2 and AS/NZS 3000 strictly govern how energy storage systems must isolate from the grid during an outage. An accredited installer must address three critical elements:
- Automatic Changeover Switch: Electrically disconnects your home from the street within milliseconds of an outage, preventing hazardous backfeeding into the Energex distribution network while line crews make repairs.
- Dedicated Essential Circuits Sub-Board: Essential circuits are physically separated from high-draw non-backup circuits (such as hot water elements, EV chargers or second-storey AC) so heavy loads do not instantly trip the inverter EPS output.
- Neutral-Earth Bonding in Island Mode: When the main grid isolator opens, a dedicated contactor maintains an earth-neutral reference so that household safety switches (RCDs) continue to protect against electrocution during off-grid operation.
Backup questions
Everything to clarify before install day.
Will a home battery automatically work in a blackout?
Not necessarily. A battery system only provides blackout power if it includes dedicated Emergency Power Supply (EPS) circuitry, automatic changeover switching and connected backup circuits. A standard grid-tied battery without backup wiring will shut down during an outage to comply with anti-islanding safety rules.
Can a home battery run ducted air conditioning during an outage?
It depends on the inverter continuous kW rating, compressor starting current and phase supply. Single-phase systems (typically 5kW EPS output) can run single split systems but usually struggle with large ducted units. Three-phase hybrid inverters (such as the FoxESS H3 series delivering 10kW to 15kW EPS output) can power ducted air conditioning if engineered with soft-start controls.
Can rooftop solar recharge the battery while the grid is down?
Yes, provided the system features black-start and island-mode frequency control. In an integrated DC-coupled hybrid system, the inverter establishes a micro-grid that wakes the solar panels up each morning, powers the home during daylight and recharges the battery modules for the following night.
How long will a 20kWh or 28kWh battery last during a storm blackout?
With an essential circuits configuration (fridge, lights, Wi-Fi, basic power points averaging 600W), a 20.72kWh battery can run for over 28 to 30 continuous hours without any solar. Under moderate loads (1.5kW to 2kW including split-system cooling), expect 9 to 13 hours. If rooftop solar recharges the battery during the day, runtime can extend indefinitely.
What switchboard modifications are needed for blackout backup?
Your electrician must install an essential circuits sub-board, automatic changeover contactor and independent neutral-earth bonding compliant with AS/NZS 4777.2 and AS/NZS 3000. This ensures all safety switches (RCDs) continue to protect your family from electric shocks even when isolated from the main grid.
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