The assumption is understandable: you have solar panels on the roof, the sun is shining, and the street goes dark. Surely you are fine?
For most Perth homes with standard grid-connected solar, the answer is no. Your inverter shuts down automatically the moment the grid loses power — and it does so by law. The panels are still receiving sunlight; they are just not allowed to send power anywhere.
The good news is that with the right battery system, you can stay powered through an outage, recharge from your panels while the grid is down, and in some cases have your system prepare itself automatically before a storm even arrives. This guide covers how it all works.
Why Your Solar Shuts Off in a Blackout
All grid-connected solar inverters in Australia are required by AS/NZS 4777.2 to disconnect from the electricity network the moment grid power is lost. This is called anti-islanding protection.
The reason is straightforward: if your inverter kept pushing power into the grid during an outage, Western Power linespeople working to restore the network could be electrocuted without warning. The inverter detects the loss of grid voltage within seconds and switches off automatically. No power flows, regardless of what the sun is doing.
This is not a flaw in your system. It is a mandatory safety feature, and every compliant grid-tied inverter in Australia works this way.
Perth’s Blackout Reality
Perth averages around 23 severe storms per year, and Western Power’s network covers one of the largest geographic service areas of any grid operator in Australia. Weather-related faults account for around 62% of outages across the state.
The June 2024 storm set a record by damaging 327 infrastructure components in a single day, leaving some suburbs without power for up to 18 hours. Summer heatwaves also put the grid under pressure — high air conditioning loads have caused voltage dips and planned load-shedding events in suburban Perth in recent years.
For Perth homeowners, backup power is not a theoretical edge case. It is a practical consideration with a predictable frequency.
What You Need to Stay Powered
Two things are required to maintain power during a grid outage:
- A battery with island-forming capability — the ability to create its own local power supply that your home runs on independently of the grid.
- A hybrid or multimode inverter — one that can continue operating in off-grid mode and keep drawing power from your solar panels while disconnected from the network.
Not all battery systems can do this, and among those that can, some require additional hardware — a gateway or backup box — to enable the function.
Backup configurations also come in two forms. Whole-home backup powers every circuit in the house. Essential circuits backup covers only selected circuits — typically lights, fridge, and a handful of power points — at a lower installation cost. Which approach suits you depends on your budget, your home’s wiring, and what you need to run during an outage.
The Four Positive Energy Solutions Backup Options
Each of these systems has a dedicated backup power guide in the Positive Energy Solutions blog. See the related reading links at the end of this post.
Smart Storm Prep: What Each System Does Before a Blackout Hits
One of the most practical differences between battery systems is how they handle advance warning. Perth’s storms are forecast hours — sometimes days — in advance. Some systems act on that information automatically. Others give you the tools to act manually.
Tesla Powerwall 3 — Storm Watch
The Tesla app includes a feature called Storm Watch. When severe weather is detected in your area through national weather forecast data, Powerwall automatically begins charging to 100%, overriding normal time-of-use settings. You receive a notification in the app confirming Storm Watch has activated. No action is required on your part.
SigEnergy SigenStor — AI-Enabled Forced Charging
The SigenStor’s AI energy management system monitors weather forecasts and grid signals. When adverse conditions are predicted, the system proactively pre-charges the battery without prompting. You can also trigger a manual forced charge through the monitoring portal at any time. The AI component improves over time by learning your household usage patterns, which sharpens its prediction of when and how much to pre-charge.
Fronius GEN24 Plus — SolarWeb Manual Force Charge
The Fronius SolarWeb app gives you manual control via the Battery Control feature. Tapping Start under Battery Control triggers a forced charge to 100%, drawing from solar and the grid if needed, and holds that level for 24 hours. If an outage extends beyond that window, you can restart it. Fronius also allows a permanent Reserve Capacity setting in the inverter — for example, reserving 50% means the battery never discharges below that threshold during normal operation, keeping a buffer available at all times.
Sungrow SBR/SBH — iSolarCloud Forced Charge and Backup Mode
The iSolarCloud app includes a forced charge function with a configurable target state of charge and time window. A Backup Mode setting allows you to reserve a set percentage of battery capacity permanently. With 30% reserved, for example, the battery never discharges below 30% during normal grid-connected operation, keeping that capacity available for outages. Sungrow does not have an automated weather-trigger feature, but the manual tools in iSolarCloud give you full control when a storm is forecast.
What Actually Runs During a Blackout
When the grid drops and your system switches to island mode, your home runs from the battery. During daylight hours, your solar panels continue generating — that power feeds directly into your home and any surplus goes into the battery. At night, the battery is your only source.
How long the battery lasts depends on three things: its capacity, what you are running, and whether the sun is shining. As a rough guide for a 13.5 kWh system — a common Perth battery size:
Estimates only. Actual duration depends on the appliances running in your home — every household is different. Other factors include battery state of charge at time of outage, ambient temperature, and solar generation during daylight hours. Solar recharging during the day significantly extends backup duration in multi-day outages.
Load Management During a Blackout
How you manage what you run during a blackout is the single biggest factor in how long your battery lasts. A few appliances account for the vast majority of draw, and avoiding or limiting them makes an outsized difference.
High draws to avoid or use sparingly:
- Air conditioning (2–5 kW continuous): the largest single load in most Perth homes. Use fans instead where possible, or run AC sparingly in short bursts rather than continuously.
- Electric oven or cooktop (2–4 kW): use a microwave or gas alternative. An induction cooktop on high can drain a 13.5 kWh battery in a few hours on its own.
- Pool pump: turn off during any backup event. It adds 0.5–1.5 kW of continuous draw with no benefit during an outage.
- Electric hot water system (2.4–4 kW): your tank should already be hot. Avoid triggering a reheat cycle during the outage.
- EV charging: pause any charging session. Even a slow 7 kW home charger will rapidly deplete your battery reserve.
Lower-draw items that are fine to run:
- Fridge and freezer (100–200 W combined)
- LED lighting (5–10 W per globe)
- Phone and laptop charging (50–100 W)
- Ceiling fans (50–75 W each)
- Television and streaming devices (100–200 W)
- Internet router and modem (10–20 W)
A useful rule of thumb: if it produces heat or cold, it draws a lot of power. Prioritise essentials, let your solar panels recharge the battery during daylight hours, and avoid stacking high-draw appliances at the same time.
What Will Not Work Even With Battery Backup
Even a well-specified backup system has limitations worth understanding before you need them:
- Three-phase appliances: most Perth homes are single-phase. If your backup covers one phase, appliances that require three-phase power — some large ducted air conditioning systems, some workshop equipment, and some ovens — will not operate during an outage.
- Grid export is disabled: when your system is islanded, any solar generation beyond what your home is using cannot be exported to the network. You will not lose that energy — it goes into the battery or is curtailed if the battery is full — but you will not earn feed-in credits during the outage.
- DEBS credits are paused: Synergy’s Distributed Energy Buyback Scheme does not pay for energy during an islanded backup event.
- Some appliances may need manual restart: appliances that were running when the grid dropped may trip their internal protections. Once backup power is active, check any appliances that were in use and restart them if needed.
How to Prepare Before a Storm
If severe weather is forecast for Perth, here is what to do depending on your system:
- Tesla Powerwall 3: Storm Watch activates automatically. Open the Tesla app to confirm it has triggered and check your battery level. If Storm Watch has not activated, you can manually raise your backup reserve under Settings.
- SigEnergy SigenStor: the AI system will pre-charge automatically if adverse weather is forecast. Log into the monitoring portal to confirm charging is in progress, or trigger a manual forced charge if the storm is imminent.
- Fronius GEN24 Plus + Reserva: open the Fronius SolarWeb app, go to Battery Control, and tap Start to force a full charge. This locks at 100% for 24 hours. If you have not already set a Reserve Capacity percentage in the inverter settings, consider doing this now for permanent peace of mind.
- Sungrow SBR/SBH: open iSolarCloud and set a Forced Charge to 100% with a time window that covers the forecast period. Alternatively, ensure your Backup Mode reserve SOC is set to a level you are comfortable with.
Regardless of brand: know which circuits are included in your backup before you need them. This should have been confirmed with your installer at commissioning. If you are not sure, contact Positive Energy Solutions and we can walk you through it.
If a multi-day outage is possible, prioritise essentials, manage your loads as outlined above, and let your solar panels do the recharging during daylight hours each day.
Find Out Which Backup System Is Right for Your Home
Battery backup is not one-size-fits-all. The right system depends on whether you want whole-home or essential circuits backup, which brand best suits your existing or planned solar setup, and what your budget allows. Positive Energy Solutions designs and supplies backup-capable battery systems across Perth — contact our team for a quote tailored to your home and your backup requirements.
Related guides
- Fronius GEN24 PLUS Backup Power for Perth Homes
- SigEnergy SigenStor Backup Power for Perth Homes
- Sungrow Solar Battery Backup Power for Perth Homes
- Tesla Powerwall 3 Backup Power for Perth Homes
Frequently Asked Questions
Will my solar panels keep working in a blackout?
Not on their own. Standard grid-connected solar inverters shut off automatically when the grid loses power under AS/NZS 4777.2. This is a mandatory safety requirement. Your panels are still generating, but the inverter disconnects from the grid and stops converting that power. You need a battery with island-forming capability to stay powered.
Do I need a special battery for blackout protection?
You need a battery that includes island-forming (backup) capability, paired with a hybrid or multimode inverter. Not all batteries offer this. Among the systems Positive Energy Solutions supplies, Tesla Powerwall 3, SigEnergy SigenStor, Fronius GEN24 Plus with Reserva, and Sungrow SBR/SBH all provide backup capability. The hardware required varies by brand.
Can I run my air conditioning during a blackout?
Technically yes, if your backup covers the relevant circuit. Practically, running air conditioning significantly shortens how long your battery lasts — a 2.5 kW reverse-cycle unit can reduce backup duration from 20+ hours to 4–8 hours on a 13.5 kWh battery. If a long outage is possible, use fans and run AC sparingly.
How long will my battery last in a blackout?
It depends on your battery size and what you run. A 13.5 kWh system powering a fridge, lights, fans and devices can last 20 or more hours. Add air conditioning and that can drop to 4–8 hours. If your solar panels are generating during the day, they will recharge the battery and extend backup duration significantly. This is particularly important in multi-day outages.
Does the CHBP rebate still apply to backup-capable batteries?
Yes. All four backup-capable batteries in the Positive Energy Solutions range are on the Clean Energy Council Approved Products list and eligible for the federal Cheaper Home Batteries Program discount. Tesla Powerwall 3 also qualifies for the federal rebate, though it is not currently on Synergy’s Supported Solutions List for the separate WA state rebate. See our Cheaper Home Batteries Program Perth 2026 guide for current figures.
What happens to my Synergy feed-in credits during a blackout?
Synergy’s DEBS feed-in credits are not earned while your system is operating in island (backup) mode. Any excess solar generation during the outage goes into your battery or is curtailed. It cannot be exported to the network when you are disconnected from it. Credits resume as normal once the grid is restored and your system reconnects.
Will my system reconnect automatically when the grid comes back?
Yes. When Western Power restores grid power, your hybrid inverter detects the return of grid voltage, runs a brief synchronisation check, and reconnects automatically. Most systems complete this within 60 to 90 seconds of grid restoration. You do not need to do anything — the transition back to normal grid-connected operation is automatic.
About the Author
Jason Wiktorowicz
Sales Manager, Positive Energy Solutions | Perth, WA
Jason has been at the centre of Western Australia’s energy transition for over a decade. As Orchestration Lead on Project Symphony — WA’s largest virtual power plant pilot — and Stream Lead on Project Encore, he worked directly with AEMO, Western Power and Energy Policy WA to shape how distributed energy resources connect and operate on the SWIS. That work included developing and rolling out CSIP-AUS, now mandatory for all new WA grid connections. He also led Emergency Solar Management (ESM), the first program of its kind in WA, VPP for Schools (VPP4S), which provided direct market benefits through Supplementary Reserve Capacity, and REBAR, the WA Residential Battery Rebate scheme.
His earlier career spanned Synergy, Infinite Energy and Curtin University’s Sustainability Policy Institute, where he co-authored peer-reviewed research on net-zero urban precincts, solar integration and peer-to-peer energy trading, published in the journal Urban Planning in 2018.
At Positive Energy Solutions, Jason leads sales with a focus on system design accuracy and long-term performance. Positive Energy Solutions installs solar and battery systems, EV chargers and heat pumps, and holds partner accreditations with Fronius, SigEnergy, iStore and SunPower. Connect with him on LinkedIn.
