Keeping the power on in a Pakenham blackout.
Your solar shuts down the moment the grid goes out, even at midday in full sun. And a battery on its own does not fix it. Here is what actually keeps a Cardinia Shire house running through a storm outage, what it costs, and who genuinely needs it.
Your solar goes dark with everyone else's.
No, your solar will not keep working in a blackout - not on its own, and this catches almost everyone. A standard grid-connected solar system shuts down within seconds of the grid going out, even at midday in full sun.
That is not a fault. It is anti-islanding protection required by AS/NZS 4777.2, and it exists so your roof cannot energise a line that a United Energy crew has isolated and is working on. Without it, a linesman touching a supposedly dead wire in your street gets 240 volts from your house. It is one of the few rules in this trade that nobody argues with.
So on a hot January afternoon with the array producing 5kW, your house goes dark like everyone else's, and $9,000 of panels sits idle on your roof while your neighbour without solar makes exactly the same jokes about it. The only way to have power in an outage is a battery plus the backup hardware that safely disconnects you from the grid first.
And a battery alone does not fix it either.
This is the single most misunderstood thing we deal with. A battery stores energy but it cannot legally release it into your house during an outage unless there is a changeover device physically separating you from the grid first.
Plenty of Pakenham homes have a battery, lost power in a storm, and discovered on the night that they had bought storage without backup. The battery was sitting there at 80 percent, doing nothing, because nothing in the install allowed it to run the house in island mode. Those calls come in the morning after every big front and they are hard conversations, because the customer was never told and reasonably assumed.
Backup is a separate line item and it needs to be specified deliberately. If backup is why you want the battery, say so at the quote stage - it changes the product choice, not just the price. Our Powerwall vs Sungrow vs BYD comparison covers how differently the three brands handle it.
What backup actually requires.
Three things beyond the battery itself:
- A changeover device. A gateway or automatic transfer contactor that detects the grid failure and physically opens the connection to the street within milliseconds, so your battery can energise your house without back-feeding the network. This is the non-negotiable part.
- A backup sub-board, usually. Rather than backing up the whole house, most systems run a separate essential-circuits sub-board with the loads you actually care about wired to it. Cheaper, and it stops someone switching on the ducted cooling at 2am and flattening the battery.
- The wiring and re-configuration. Splitting existing circuits out of your main board onto the backup board is real electrical work, and on the newer Cardinia estates the main switchboard is often already full, so a board upgrade comes into it.
Budget $1,500 to $3,500 for proper backup on top of the battery, driven mostly by how many circuits you want and the state of your switchboard. Whole-home backup via something like a Tesla Backup Gateway sits at the top of that range and needs the battery sized to match. See our battery storage page for the sizing side and pricing for the full bands.
Choosing the essential circuits.
This is the bit worth thinking about properly before we come out, because moving a circuit later is another call-out. The sensible Pakenham list:
- Fridge and freezer - the obvious one, and the one that pays for itself in a long outage
- Lighting circuits - low draw, high value
- A few general power points, ideally in the kitchen and the lounge
- Internet, modem and router - a day working from home instead of a day lost
- The ducted heating fan - the one people forget. A Cardinia winter outage at 6C is miserable without it, and a gas ducted unit needs only its fan and controller powered, which is a modest load. This is the single highest-value circuit in a winter outage and it is routinely left off the list.
- Water pump, if you are on tank water - non-negotiable if it applies to you
What a battery actually runs when the street is dark.
More than people expect, if you choose the circuits properly rather than trying to run everything. A 10kWh battery holding a typical 9kWh usable will comfortably run a fridge, lighting, power points, internet and the ducted heating fan for roughly 24 hours - probably longer, because the sun comes up and your array recharges it during the outage as long as your system is configured for it.
That last point is worth dwelling on. A properly configured backup system does not just give you a battery's worth of energy. It gives you an off-grid house that recharges every day. In a three-day summer outage, a Pakenham home with 6.6kW of solar and a 10kWh battery in island mode is effectively self-sufficient for the essential circuits, indefinitely. That is a very different proposition to a generator with a jerry can.
What it will not run is the things that draw hard: ducted refrigerated cooling, an induction cooktop at full tilt, an electric hot water element, or an EV charger. A 7kW charger empties a 10kWh battery in well under two hours. The realistic goal is not business as usual. It is a comfortable, safe, connected house for a day or two while everyone else empties their fridge into an esky.
Worked example - a Pakenham Upper storm outage.
Semi-rural block off the Upper road, tank water with an electric pump, gas ducted heating, 6.6kW array, 10kWh battery with an essential-circuits backup board. A June westerly takes out lines across the area on a Thursday evening. Restoration Saturday afternoon.
- Fridge and freezer, 24 hours: about 1.8kWh
- Lighting and power points, evening: about 1.2kWh
- Ducted heating fan and controller, cycling: about 2.0kWh
- Internet, modem, devices: about 0.5kWh
- Water pump, household use: about 0.8kWh
- Daily essential draw: roughly 6.3kWh against 9kWh usable
- Winter solar recharge, poor June day under cloud: roughly 2.5 to 4kWh
Net result: the battery carries the household through Thursday night comfortably, dips on Friday because winter generation is weak, and is running low but functional by Saturday morning. They had heat, water, light and internet for the whole event. Their neighbours did not. Note that this is a winter case - the same event in January would have been trivial, with the array fully recharging the battery every day. Winter is the honest test, and it is why we size on a bad June day rather than a good January one.
The Cardinia outage pattern, and the honest test.
Outages happen enough to matter here, and the pattern is very specific to this corridor. United Energy's network out here runs a lot of overhead line through open country and treed areas on the Pakenham Upper and Beaconsfield Upper side, and the outages come in two flavours.
Short ones - a few minutes to an hour - happen several times a year from a branch, a bird or a car. Annoying, and enough to reset every clock in the house. The ones people remember are the storm outages: a serious westerly or a summer storm front takes lines down across a wide area, and restoration is measured in hours or occasionally days, because crews work the biggest faults first and a semi-rural street is rarely first. Homes on the fringes wait longest. If you are on a tank pump, that matters more than convenience.
Is it worth it?
It depends entirely on what an outage actually costs you, and we would rather ask than assume.
For a standard Officer or Lakeside house on town water and mains sewer, an outage is a genuine inconvenience and a lost fridge, and $1,500 to $3,500 for backup is a comfort purchase. A fair one, but a comfort purchase, and we will say so.
For a home on a rainwater tank with an electric pump, or a septic pump, or with medical equipment, or a home office where a day offline costs real money, backup is not a luxury and the arithmetic is completely different. The semi-rural fringes of the Shire - Pakenham Upper, Beaconsfield Upper, Maryknoll, Gembrook - are where this stops being a nice-to-have.
The honest test we give people: how many hours were you out last time, and what did it cost you? If the answer is a soft one, put the money into more battery instead, or into a bigger solar and battery system that saves you money every single day rather than three days a year. Backup earns nothing on the 362 days the grid behaves. That is not an argument against it - it is an argument for being clear-eyed about which of the two things you are actually buying.
Backup questions we get asked.
Will my solar keep working in a Pakenham blackout?
No - not on its own, and this catches almost everyone. A standard grid-connected solar system shuts down within seconds of the grid going out, even at midday in full sun. That is not a fault, it is anti-islanding protection required by AS/NZS 4777.2, and it exists so your roof cannot energise a line that a United Energy crew has isolated and is working on. Without it, a linesman touching a supposedly dead wire in your street gets 240 volts from your house. So on a hot January afternoon with the array producing 5kW, your house goes dark like everyone else's. The only way to have power in an outage is a battery plus the backup hardware that safely disconnects you from the grid first.
Does a home battery give you blackout backup automatically?
No, and this is the single most misunderstood thing we deal with. A battery stores energy but it cannot legally release it into your house during an outage unless there is a changeover device physically separating you from the grid first. Plenty of Pakenham homes have a battery, lost power in a storm, and discovered on the night that they had bought storage without backup. Backup is a separate line item: a changeover contactor or gateway, usually a backup sub-board, and the wiring to it. Budget $1,500 to $3,500 on top of the battery. If backup is why you want the battery, say so at the quote stage - it changes the product choice, not just the price.
What can a battery actually run during a Pakenham blackout?
More than people expect, if you choose the circuits properly rather than trying to run everything. A 10kWh battery holding a typical 9kWh usable will comfortably run a fridge, lighting, power points, internet and the ducted heating fan for roughly 24 hours - probably longer, because the sun comes up and your array recharges it during the outage as long as your system is configured for it. What it will not run is the things that draw hard: ducted refrigerated cooling, an induction cooktop at full tilt, an electric hot water element or an EV charger. The realistic goal is not business as usual. It is a comfortable, safe, connected house for a day or two while everyone else empties their fridge.
How often does the power actually go out around Pakenham?
Enough to matter, and the pattern is very specific to this corridor. United Energy's network out here runs a lot of overhead line through open country and treed areas on the Pakenham Upper and Beaconsfield Upper side, and the outages come in two flavours. Short ones - a few minutes to an hour - happen several times a year from a branch, a bird or a car. The ones people remember are the storm outages: a serious westerly or a summer storm front takes lines down across a wide area and restoration is measured in hours or occasionally days, because crews work the biggest faults first and a semi-rural street is rarely first. Homes on the fringes wait longest. If you are on a tank pump, that matters more than convenience.
Is blackout backup worth the extra cost in Pakenham?
It depends entirely on what an outage actually costs you, and we would rather ask than assume. For a standard Officer or Lakeside house on town water and mains sewer, an outage is a genuine inconvenience and a lost fridge, and $1,500 to $3,500 for backup is a comfort purchase - a fair one, but a comfort purchase. For a home on a rainwater tank with an electric pump, or a septic pump, or with medical equipment, or a home office where a day offline costs real money, backup is not a luxury and the arithmetic is completely different. The honest test we give people: how many hours were you out last time, and what did it cost you? If the answer is a soft one, put the money into more battery instead.
Backup systems across the Shire.
Want the lights on when the street goes dark?
We size the battery on a bad June day rather than a good January one, price the backup hardware as its own line so you can see exactly what it costs, and help you pick the essential circuits that actually matter. CEC-accredited, AS/NZS 5139 compliant, United Energy approved.