In short
In Queensland, new and replacement solar and battery systems with a combined inverter capacity of 10 kVA or more must be fitted with a generation signalling device, so Energex or Ergon can switch them off for a short time in an energy emergency. It is a last resort, used only at the direction of the national market operator when sunny weather and very low demand put the grid at risk, and the Queensland Government says it has not been used to date. It does not change which electricity plan suits a solar home.
If you are getting quotes for solar or a battery this spring, one line may have turned up that you have not seen before: a device that lets the network turn your system off. It sounds worse than it is, and it is also not nothing. Here is who it covers, when it can be used, and the one thing it does not touch, which is how you choose a plan.
What the emergency backstop is
On sunny, mild days, usually in autumn and spring, rooftop solar covers so much of the demand that large power stations are asked to produce very little. The market operator calls this minimum system load. Those power stations also provide services that keep the grid stable, and if demand falls too low the grid can become unsafe, with the risk of widespread blackouts.
The market operator's first steps are on the grid side: recalling planned transmission outages, reducing grid-scale generation, raising demand from large users. It switches to rooftop solar management only if those steps have not been enough, and it issues notices at three levels along the way. The national plan for consumer energy resources requires each state and territory to have an emergency backstop for this situation.
Queensland's version is described on the Queensland Treasury's page. The device the network uses to switch systems off is called a generation signalling device, and the page says it lets Ergon Energy and Energex switch these systems off for a short time during an energy emergency.
Which systems it covers
The Treasury page says all new and replacement inverter energy systems, which means rooftop solar and batteries, with an aggregate capacity of 10 kVA or more must be fitted with the device. Read that as the size of the inverters, not the panels, and as new or replacement systems, not existing ones.
Plenty of home systems are smaller than that, and the page does not list them. If you are not sure whether yours is covered, ask your installer to say in writing what the network requires for your system, and ask Energex if the answer is unclear. The page asks installers and retailers to contact the network about the device.
When can it be used
Only as a last resort and only at the direction of the Australian Energy Market Operator, under its minimum system load arrangements for a declared energy emergency. The Treasury page says it has not been used to date. The page does not say how long a switch-off would last, how households would be told, or whether anyone would be compensated, so we cannot tell you any of those things either.
What it means for your savings
For most solar households it will mean nothing, and the likeliest days for an event are mild, sunny, low-demand days when the system is exporting a lot. On such a day a switch-off would cost the credit for the energy you did not export and any power your home would have used from the panels. That is a small, occasional loss, set against the savings from the rest of the year.
It does not change how to pick a plan. A solar home's bill is still decided by the daily supply charge, the usage rate at the times you draw from the grid, and the feed-in tariff on what you export. What can change the answer is the size of the system relative to your daytime use, and whether you add a battery. Our answer on the best feed-in tariff in Queensland goes through the trade-off, and the Solar Sharer guide covers the plan type with free midday power, which the Australian Government describes on its Solar Sharer page.
If you are about to buy
- Ask the installer whether your system will need the device, and what it adds to the quote.
- Ask for the inverter capacity, in kVA, in the quote. The 10 kVA test uses the total across all inverters, including a battery inverter.
- Use an approved seller. The Treasury page recommends sourcing quotes from reputable suppliers and names the New Energy Tech Consumer Code as the standard to look for.
- Check the plan after the system goes in. Your usage pattern changes, and a plan chosen before the panels may not suit the house afterwards.
- If you rent, the landlord's choices come first. See solar for renters.
Quick answers
Can Energex switch off my solar panels?
For new and replacement systems with a combined inverter capacity of 10 kVA or more, yes. They must be fitted with a generation signalling device that lets Energex or Ergon Energy switch the system off for a short time in an energy emergency. It is a last resort at the direction of the national market operator, and the Queensland Government says it has not been used to date.
Does the emergency backstop apply to my existing solar system?
The Queensland Treasury's requirement is for new and replacement systems of 10 kVA or more of combined inverter capacity. It does not describe existing or smaller systems as covered. If you are unsure about yours, ask your installer or Energex.
When would the emergency backstop be used?
Only in an energy emergency, at the direction of the Australian Energy Market Operator, when high rooftop solar output and very low demand put the grid at risk. That combination is most likely on sunny, mild days in autumn and spring. The market operator tries grid-side steps first.
Does the emergency backstop change which electricity plan is best?
No. Your bill still depends on the supply charge, the usage rate when you draw from the grid and the feed-in tariff on your exports. What matters more is your system size, your daytime use and whether you add a battery, so compare plans on your own usage after the system goes in.
Sources
Official pages this article draws on. If one of them changes, tell us and we will update the article.
- Queensland’s emergency backstop mechanism · Queensland Treasury
- Fact sheet: Minimum system load · Australian Energy Market Operator
- Solar Sharer Offer · Australian Government, energy.gov.au