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Rooftop solar generates around 14% of Australia’s electricity demand, as more than one in three freestanding households own a system. Our electricity system operator needs an emergency plan for the rare occasions when multiple things go wrong, and uncontrolled rooftop solar generation threatens system security. NSW is set to be the latest Australian state to introduce an Emergency Backstop Mechanism – here’s what it all means.
Australia’s rooftop solar is a global success story of the clean energy transition. But a success story at this scale also changes how the electricity network is operated and introduces new challenges.
Unlike more conventional generators such as coal and gas, rooftop solar is not easily turned on or off or adjusted. It also depends on weather conditions (sun, temperature, cloud cover, etc.). During the middle of the day, as millions of systems generate their peak power output, the electricity network experiences its minimum demand, which is low demand from the grid. In states like South Australia, demand can even go negative when rooftop solar can generate more than the entire state’s electricity demand.
This is exactly where the Emergency Backstop Mechanism (EBM) comes in, which could be thought of as emergency brakes on a train. It is not used under normal conditions, but when an unusual combination of events creates a genuine safety risk, operators need to know that the brake is available and will temporarily stop rooftop solar generation.
The electricity system must continuously balance supply and demand. Rooftop solar first supplies the home or business where it is installed. This reduces the amount of electricity customers draw from the main grid. However, under sunny conditions with low energy demand in the home, a large proportion of rooftop solar generation is exported to the grid. Sunny conditions or low demand do not, by default, threaten the grid. However, challenges may arise when high rooftop solar exports coincide with other problems, such as a large-scale generator trip, a transmission-line outage, or a region or state becoming separated from the rest of the electricity grid.
Some of the larger-scale grid equipment and generators need to remain online to provide essential services such as system strength and inertia, voltage regulation, and frequency support. If demand falls too far due to rooftop solar exports, there may not be enough ‘room’ to keep the required equipment online while accounting for potential network contingencies and failures.
A mild-temperature, clear spring Sunday with lower demand and high solar exports is a likely candidate for the backstop to intervene. However, on a hot or cold weekday, when heating or cooling demand is higher, solar exports are absorbed by the network. On days with higher solar exports, a network outage and/or equipment failure can quickly narrow power system security headroom, increasing the risk for power system security.
Figure 1 Example conditions for Emergency Backstop Mechanism (source: AEMO rooftop solar fact sheet)
To reiterate, the problem is not simply ‘too much solar exports’, but rather the rare combination of high exports, low operational demand, and another significant power-system issue. Australian Energy Market Operator (AEMO) notes that these conditions are rare. The backstop remains the last resort to implement before trying other solutions. One example is constraining and directing non-essential grid-scale generation and increasing electricity demand by directing large consumers to absorb excess solar exports.
For most customers, a backstop activation should not interrupt the grid supply to the property. It may, however, temporarily reduce solar exports or stop generation entirely. As a result, the home will draw more electricity from the grid or its battery during this period. The customer may lose some solar production, battery charge or feed-in-tariff revenue during the event; however, these events have been rare and short-lived. A research project is currently quantifying the implications for solar and battery owners, as well as Virtual Power Plant participants.
Whether your rooftop solar can continue serving the home or charging a battery depends on the backstop instruction and the system design. A zero-export instruction may still allow solar to supply household loads and charge a battery. A zero-generation or inverter-disconnection instruction may not.
Hybrid inverters, AC-coupled batteries, and backup circuits can also respond differently. In Queensland, for example, a Generation Signalling Device (GSD), which is used to implement EBM, usually disconnects the affected inverter and stops generation. This includes generation for self-consumption. Similarly, when Enhanced Voltage Management is activated, which is another method to implement EBM, both the solar and battery inverters can trip. Activating a backstop through CSIP-Aus provides the most refined control, as it can allow zero export without affecting self-consumption or battery charging.
AEMO identified the emerging minimum-system-load risk and recommended that governments and distribution networks develop emergency capabilities. South Australia was the first NEM jurisdiction to act through its Smarter Homes regulations, which took effect on 28 September 2020.
AEMO subsequently introduced its coordinated Minimum System Load framework in 2021. Other jurisdictions followed with their own arrangements.
Queensland‘s requirements commenced on 6 February 2023 for applicable new, upgraded, and replacement inverter energy systems with a capacity of 10 kVA or more. Victoria introduced its mechanism for larger systems above 200 kW in October 2023, and for smaller rooftop systems from 1 October 2024. NSW is progressively introducing requirements for new and upgraded rooftop solar systems up to 200 kW from mid-November (SolarQuotes will produce a dedicated explainer on the NSW in the coming weeks).
In simple terms, AEMO determines when the wider power system needs a backstop, while state governments and distribution network service providers (DNSPs) establish the mechanisms that can deliver it. Different DNSPs use different tools, and several methods may operate together.
A DNSP can send an instruction from its utility server using the Common Smart Inverter Profile – Australia, or CSIP-AUS. The instruction may reach the inverter directly, through the inverter manufacturer’s cloud platform, through an aggregator, or through a gateway installed at the property.
Depending on the jurisdiction and the type of emergency instruction, the system may be directed to reduce exports, set exports to zero, reduce generation, or temporarily stop generating, as shown in previous emergency backstop implementations.
How a CSIP-AUS emergency instruction reaches your inverter.
This approach can be targeted and measurable, but it depends on the communications capability and compatible inverters. Considering most of our rooftop solar fleet is not CSIP-Aus-capable, this method may have limited capacity. Moreover, a compatible inverter may be incorrectly registered, the internet connection may fail, or the manufacturer may no longer support its cloud service.
Given that most of our rooftop solar fleet is not CSIP-Aus compatible, the backstop has been implemented using a more contentious method known as Enhanced Voltage Management (EVM).
EVM deliberately increases distribution network voltages to high levels (above 258V) to trigger inverter grid protection settings. This is done in accordance with the Australian grid connection standard AS/NZS 4777.2.2020. This creates limits for sustained operation and anti-islanding. These settings in return trip inverters and cease generation.
One reason this method is controversial is that high voltages not only trip inverters but also damage certain appliances. So far, no clear data shows the extent of appliance malfunction or damage when an EVM is applied. Still, all appliances and the distribution network should keep voltages within their safe operational limits. The recommendation is within +10% (253V) and – %6 (216V) of the nominal 230 V.
Queensland is the only state that continues to use Audio Frequency Load Control (AFLC) to manage rooftop solar. A Generation Signalling Device, or GSD, receives an AFLC signal sent through the electricity network and activates a standard demand-response mode in the inverter.
It does not rely on the customer’s home internet, but the device must be correctly selected, installed, wired and commissioned.
Under Queensland’s GSD arrangement, the signal can disconnect the inverter, stopping generation. When the emergency ends, another signal allows the inverter to reconnect, with a fail-safe reset also built into the arrangement. Queensland now allows either GSD or CSIP-AUS pathways for applicable connections, subject to network requirements.
Many large commercial solar systems above 200 kW communicate with the network via a supervisory control and data acquisition (SCADA) system. This provides the network with a more direct and visible way to monitor and reduce the system’s output when needed.
South Australia Power Networks (SAPN) has used SCADA control of larger distributed solar systems during actual minimum-demand events.
As an absolute last resort, if sufficient headroom can’t be achieved through the methods discussed above during a network emergency, AEMO and DNSPs may need to disconnect entire distribution feeders with high solar exports, which carry power from households towards the transmission network.
This broader measure can have a significant impact on customers and equipment. Disconnecting an entire feeder can interrupt the electricity supply to many customers, rather than reducing their solar output, as the previous method did.
That is why the control and management of rooftop solar are critical, and a reliable, targeted backstop is preferable to relying on these higher-impact measures. This high-impact measure hasn’t been implemented to date and is only required as an absolute last resort.
These concepts can be easily confused because they may use the same inverter, internet connection and CSIP-AUS communication standard.
A static export limit is a fixed export limit that doesn’t vary over time. For example, new residential systems in South Australia that don’t want CSIP-Aus communication will be capped at 1.5 kW export.
The dynamic operating envelope (DOE), or flexible export limit, varies with the available capacity in the local network. This is like ramp signals regulating how many cars can enter a busy motorway. CSIP-Aus is the most common method for implementing DOE or flexible exports.
The Emergency Backstop Mechanism is more like closing the motorway after a serious accident. It is a temporary system-security action used after other practical options have been exhausted. A backstop instruction also takes priority over ordinary dynamic export instructions.
South Australia provides the clearest published examples because it has a very high proportion of rooftop solar and reaches minimum-demand conditions that threaten system security. A summary of the events is provided in the following table.
Table 1: Summary of Emergency Backstop Events in Australia
Apart from these actual backstop events in South Australia, it has not been required in any other states to date. However, most DNSPs run ‘fire-drill’ tests to monitor and check the capability of backstop measures.
For installers, correctly setting up CSIP-Aus and ensuring emergency backstop compliance is critical. When more systems can be controlled via CSIP-Aus during these emergency events, it will reduce the requirement for EVM or feeder shedding, which has more significant implications for customers and home appliances. A compliant inverter that was never registered, linked to the correct utility server or configured for the required response is like a smoke alarm without a battery. It may appear complete but fail to operate when it is needed.
Installers should:
Setting up internet connectivity, ensuring DNSP portal registration, performing firmware updates, and securing long-term manufacturer cloud support are now part of a good system handover. Installers should communicate relevant challenges (if any) related to these steps so that inverter original equipment manufacturers (OEMs) and regulators can take the necessary steps to ensure smoother installation processes.
Industry reports highlight that proper installer training and education are critical to ensure compliance. If network operators overestimate compliance and the number of systems that will respond during an emergency, they may need to use broader measures with greater customer impact.
If we have these measures in place and implemented well, then the likelihood of needing a backstop will reduce.
Supporting an emergency backstop does not mean accepting routine or unlimited intervention. It must not replace the hard work of effectively integrating various consumer energy resources (CER). An emergency backstop can be reduced with:
These measures should form the backbone of our future grid with high CER penetration, and a backstop should be used only in emergencies.
Moreover, in July 2026, the Australian Energy Market Commission (AEMC) opened a consultation on a proposed Minimum System Load governance framework. It’s a possible reserve service through which responsive loads, including large batteries, pumped hydro, and behind-the-meter resources, could be paid to increase demand during forecast periods of minimum load. This would reduce the number of instances and the relevant network security risks associated with the minimum system demand.
Regulation should ensure that an emergency backstop activation:
Backstop activations should also be reported transparently. This includes the reason for the event, its duration, the estimated amount of solar curtailed, and any problems with restoring systems. Cybersecurity, privacy, customer communication, equipment support, and responsibility when systems fail also need clear ownership. AEMO’s implementation review identifies governance gaps in consumer protections, large-scale testing, ongoing communications, and responsibility for returning systems to service.
For system owners, the emergency backstop should mean rare and temporary reductions in generation, not routine interference with a solar investment. Ongoing research aims to quantify the impact of existing backstop events; however, according to previous AEMO reports, this impact appears to be minimal.
As a system owner, you should ask your installer how the proposed system responds to zero-export and zero-generation instructions, particularly where a battery or backup circuit is included.
For installers, communications, registration and commissioning are becoming as important as correct electrical installation. A system is not truly backstop-ready until the full signal path has been tested.
The emergency backstop is not an argument against rooftop solar. It recognises that millions of small systems now collectively form a very large power station, and that such a power station needs an emergency operating plan. On the other hand, for governments, networks and AEMO, the social license for remote control depends on restraint, transparency and continued investment in better alternatives.
SolarQuotes will be covering the kickoff of the NSW Emergency Backstop Mechanism in coming weeks – sign up to our free weekly newsletter to get all our coverage. 
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Baran Yildiz is a Senior Lecturer at the School of Photovoltaic and Renewable Energy Engineering (SPREE), UNSW. He completed his PhD and M.Sc. in Renewable Energy Engineering, SPREE, UNSW and B.Sc. with Honors in Mechanical Engineering, Bogazici University, Istanbul, Turkey. Baran’s research is multi-disciplinary and involves collaboration with the key industry partners of Australian energy sector. His research focuses on the integration of consumer energy resources (CER) and flexible demand, and he is currently leading Project CICCADA (ARENA), SolarShift (RACE for 2030) and PLUS ES South Australian demand flexibility trial (ARENA). Baran’s research has been translated into real-world products benefiting consumers and made policy impact by leading rule changes in Australian Energy Market Commission (AEMC).
I understand that grid stability needs to take priority over everything else, and I’d be happy to enroll and configure my inverter to these external control systems.
If they want to disable exports at times, I can live with that as I only earn 1c/kWh (I’m fine with this as in exchange, I have 3 free hours to charge batteries), however if the disable PV generation, forcing me to import power to act as a grid stabiliser, then I think it’s reasonable that I receive credit for imports during this time.
Big batteries get paid FCAS payments, so why shouldn’t households enjoy the same service fee?
If EVM is ever used, it should be mandated that retailers contact their customers within 72 hours asking if any appliances have stopped working [during or post event]. We pay daily connection fees for stable grid power, where the supply exceeds national standards and electronics fail, the majority of people aren’t going to know about the correlation. The end user would blindly replace the whit
Yes, agree. We all paid to have a smart interval meter. There’s no reason why triggering an emergency backstop mechanism shouldn’t also trigger a price signal event for those affected.
It is likely that any situation needing an inverter shutdown signal would coincide with large negative spot prices.
Shutdown my inverters and pay me $1/kWh for consumption. I can help out. I’ll gladly increase my grid draw.
The market should work both ways.
In Victoria the way the Emergency Backstop Mechanism regulations have been implemented has resulted in Inverters and batteries only a few years old being sent to rubbish. Example. I have 3 phase electricity but I had a single phase Solis inverter and Alpha 10 kWh battery about 3 years old because that was the most economical way to go at the time. When the federal battery rebate came along I decided to increase panels from 6.5kW to 17 kW and go three phase with 32 kWh battery. My old inverter and battery I was giving to my daughter as second hand values had plummeted once the battery subsidy was launched. I had a contract with an installer to install my new system and move my old inverter and battery to my daughters house. After they had installed my new system and decommissioned my old inverter and battery the installers informed me that they could not go ahead with re-location to my daughters house. The Solis did not have EBM and could not do A/C charging.
The article reveals that EVM (Excessive Voltage Mismanagement) has already been inflicted on SA long-term, i.e 5 days of around 30V over the 230V norm, and well outside the +10% limit consistent with normal equipment life.
That such abuse of other people’s equipment and self-consumption is creeping in could prompt self-sufficient prosumers to install overvoltage detection, to automatically trip the grid isolator, for self-protection. Much cheaper and easier would be a simple audible overvoltage alarm, to prompt manual disconnection. That is cheaper than going wholly off-grid.
Now, if we had massive electrically powered methanol synthesis plants, pulling CO₂ from the atmosphere, to manufacture CH₃OH for farm tractors and long-range boat & caravan towing, there could be enough grid load available to productively soak up generation peaks. But that would require competent planning and execution consistent with a climate emergency.
So clobber the rats & mice instead.
Its always the case, the big boys going after us “rats and mice”. Instead of shutting us down, how about prioritsing more S t o r a g e, cracking on with building plenty capacity. Pressing the curtailment and shutdown buttons isn’t the right way.
Hi Joachim,
26 million Australians are now the world’s second biggest home battery market behind 80 million Germans.
We have a little more behind the meter battery than we do grid scale & both continue to grow.
The latter now deliver more MWH to the NEM than open cycle gas & diesel peakers combined.
We need more of everything because currently the big battery pipeline is good (quick/cheap/easy) but the wind & solar projects (bigger/slower) are being hampered by disinformation & NIMBYs
Backstop & flexible exports are simply part of the solution.
So is renationalising the grid if you ask me, if they hadn’t so far squibbed a 94 seat majority.
The EVM is already more constantly used more locally in areas where generation is high and demand low, when other appliances are affected it usually trips the circuit breaker – usually the hot water system, or a pool, etc.
We had our solar put in Nov 2023, and went straight onto flexible exports.
SAPN started that in SA across the network on July 1 same year, after trials began in 2021 in selected limited suburbs.
We have seen the annual test done, usually the total curtailment of export for an hour or so, home still had grid power and generation etc.
Just a few weeks ago noticed one day where our production dropped from high 8kw to a flatline 5kw for a couple of hours, so suspect that was some sort of curtailment.
We have ever noticed anything else in the remaining 3 years or so.
Batteries are certainly going to reduce backstop need dramatically.
We have exported 70% of our production to the grid during the 3 years to date, until the battery went in 5 weeks ago.
Now we are exporting 18%, and trying to reduce even more, soaking up as much excess as we can with the HWS and EVs, after the battery has topped off daily by late morning.
Amber customers know the fix. Introduce negative feed in tariffs and curtailment. It then imposes a financial cost on a offender who generates “excess” power.
Amber curtailment does have a flaw. It still exports at 0c feed in. They should curtails at any negative or zero. Same with every retailer. If market is 0 or negative then customers should not be paid
There needs to be a mandatory reporting regime, together with a proposed action plan by the DNSPs if this is enacted. DNSPs already have plenty of data about solar system and battery sizes, and if they cared to collate it they would also know about who has CL systems and responds to them. They should have to proactively suggest fixes such as marketing to customers to move Resistive HWS systems to the middle of the day, to propose to AEMO deployment of large batteries to absorb and inject power at key points of weakness and look at innovative solutions such as battery backed EV charging in suburban commuter parking precincts
I agree wholeheartedly with Greg’s comments.
In addition I would suggest that they go back and send their inspectors to check that each system that they have excepted into the grid system is CSIP-AUS COMPLIANT. Why should a third of all households say in Victoria, 30% of homes are fitted with Solar, loose their power just because they did not do the correct tests right from day one. If you do not export power to the grid there should not be a problem or you should not be part of their problem.
I have enough batteries to be totally self sufficient except for long cloudy periods days on end. Only really need the grid in the winter.
This is not rocket science.
Is this because the network providers are refusing to invest in storage and grid stability solutions. Its not like we did not know this problem was just around the corner. Third world country again. Australians deserve better.
I think the real problem is politicians working for corporate donors rather than serving the people that elected them.
How does the SAPN flexible exports fit along side this.
From my understanding the signalling can manage the local exports in real time.
A model that should be replicated.
We regularly export the max, but are curtailed when required.
SAPN did backstop done years ago and it was called “smarter homes” even though it was a pretty dumb on/off control, introduced with two days industry consultation & 6 weeks lead time.
Never let it be said the bureaucracy can’t move quickly when someone blinks.
A couple years on and SAPN introduced flexible exports & rolled it out over the next couple. Works well.
Victoria, having seen it done over the border, decided to reinvent the wheel five times, and the fustercluck they created is still soaking up hours of support calls, hurting the entire industry nationally. They haven’t even started with flexible connections yet.
NSW has looked to SAPN & simply decided to hang their logo on the same system.
I’ve run grid disconnected for weeks now, never get under 80% on the battery, full electric house, maybe invest in a diesel Genset for backup and cut the grid entirely
I understand that Tesla Support can adjust the grid export/inputs limits of Powerwall batteries to any values within the inverter/battery capacity. Therefore, with the minimal FIT these days, one option would be to set a zero export limit instead of having the energy supplier curtail the inverter output and prevent the house from using solar.
Seems a waste though, not feeding solar into the grid, in oder to cater for very rare events.
Please keep the SolarQuotes blog constructive and useful with these 5 rules:
1. Real names are preferred – you should be happy to put your name to your comments.
2. Put down your weapons.
3. Assume positive intention.
4. If you are in the solar industry – try to get to the truth, not the sale.
5. Please stay on topic.



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