Authorities remotely switch off thousands of SA home solar panels due to lack of power grid demand

Energy authorities in South Australia have used their new power to remotely switch off thousands of household solar panels for the first time, making the intervention when electricity demand plunged over the weekend.

Last year, transmission authorities were given permission to deliberately “trip” existing rooftop solar panels in rare circumstances to prevent sudden dips in demand leading to widespread blackouts.

The Australian Energy Market Operator (AEMO) recommended the measure as a means of mitigating the threat to grid security posed by the rapid growth of rooftop solar, which has led to days of very low demand.

Low demand poses a major problem for operating the grid securely, particularly when South Australia’s ability to export electricity to the eastern states is hampered.

AEMO said such a dip occurred on Sunday, with South Australia experiencing “near-record minimum demand levels for electricity from the grid” during a planned outage of circuits feeding the Heywood interconnector which links the state’s grid with Victoria.

That planned outage meant a tighter-than-usual limit was placed on the amount of excess power South Australia could export.

At one point, more than 70 per cent of the state’s power consumption came from rooftop solar panels alone.

In response, AEMO instructed transmission company ElectraNet to “maintain grid demand above 400 megawatts” for one hour during the afternoon.

“To preserve system security in South Australia, AEMO maintained the minimum amount of synchronous generation to maintain system security,” an AEMO spokesperson said.

SA Power Networks — which maintains the state’s energy infrastructure, including substations, poles and wires — said SA “had lower demand on Sunday than we had on Christmas Day”.

“We acted at the direction of AEMO to help them in stabilising the state grid,” spokesperson Paul Roberts said.

“We reduced solar generation from larger-scale solar connected direct to our network and about 12,000 solar customers … to achieve an increase in demand of 60MW.

South Australia has become hugely dependent on renewables to meet its energy needs in recent years.

More than four years on from the infamous 2016 statewide blackout, SA’s rooftop solar and windfarm boom has resulted in huge levels of generation from renewable sources.

About 280,000 households in South Australia — 35 per cent — have solar installed.

In June, the SA Government warned of the “risk of another statewide blackout” due to system overload, if supply were ever to outstrip demand.

For just over an hour on October 11, 100 per cent of energy demand was met by solar panels alone — making the state the first major jurisdiction in the world to be powered entirely by solar energy.

“Minimum demand events will become increasingly common throughout Australia as we continue to integrate rooftop PV installations,” AEMO said.