AEMO says Australia’s power grid could face collapse unless rooftop solar output is curtailed during emergencies.

The agency is reportedly seeking “emergency backstop” powers to switch off or reduce rooftop solar systems across all states, expanding existing measures in some regions to a nationwide framework by next year.  

Rooftop solar systems now exceed four million installations, generating power that, at times, meets more than half the demand in the National Electricity Market (NEM). 

In states like South Australia, solar occasionally provides over 100 per cent of local demand, with excess exported interstate. 

AEMO projects rooftop solar could soon supply up to 90 per cent of demand at peak times, particularly in spring, when mild weather lowers energy use.  

While renewable energy is key to Australia’s future, its rapid growth poses stability risks. “The emergency periods where this kind of intervention is required should remain infrequent, but essential for maintaining a secure and reliable supply of electricity for customers,” AEMO says in a report to be released this week.

The challenge centres on the grid’s minimum demand—power drawn from the grid excluding rooftop solar output. 

Increasing solar penetration reduces this demand to critical levels, sidelining coal and gas plants that provide essential services such as inertia and system strength. 

AEMO warns that, without intervention, the grid could become unstable, leading to blackouts or catastrophic system failure. Drastic measures such as raising voltages or disconnecting parts of the grid may otherwise be required to manage the solar overflow.  

AEMO’s potential strategies include reducing coal plant operating thresholds, deploying stabilising technologies like synchronous condensers, and upgrading inverters to support grid security. Expanding energy storage and shifting demand to midday - when solar is cheapest and most abundant - are also options.  

However, the agency insists that emergency controls for rooftop solar are essential. 

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