SA Power Networks (SAPN) will run an operation on South Australia’s grid to test the backstop mechanism—a capability that allows it to temporarily curtail rooftop solar generation to protect the grid against voltage instability.
To be conducted on Tuesday 25 August, the annual exercise is like a fire drill for the grid. It simulates a rare but urgent situation so SAPN can confirm that all systems and people are ready to respond if directed to use the backstop mechanism by the Australian Energy Market Operator (AEMO).
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AEMO monitors grid stability nationally and works to maintain system security—balancing electricity supply with demand. In South Australia, that balance can be challenging because it has more rooftop solar per capita than almost anywhere in the world.
Sometimes, when rooftop solar exports are very high and electricity demand is very low, the grid can become unstable.
In November 2022, a severe storm ‘islanded’ South Australia from the rest of the national grid when the interconnector to Victoria failed during a period of surplus energy export. Thanks to the Smarter Homes capability, SAPN was able to help maintain system stability for South Australian customers.
If AEMO forecasts a risk to system security and has already used all other available controls, it can direct SA Power Networks to increase operational electricity demand. The fastest way to do this is by temporarily reducing rooftop solar generation. If this is not done, the imbalance could lead to widespread power outages.
The curtailment test will involve approximately 100,000 customers and should last less than one hour. Systems will ramp down to 0kW, then ramp back up. On average, customers will miss about 1.5kWh of generation.
The test will be complete by sunset, and SAPN says most customers will not notice that the test is being conducted.
“Our goal is to contribute to measures that keep electricity demand and supply in balance while supporting South Australia’s transition to more renewable energy,” SAPN said in a statement.
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“Maintaining system robustness and reliability is essential. These tests are infrequent, and we work to minimise both cost and inconvenience for customers.”
