This week’s call by the Australian Energy Market Operator for “emergency backstop” mechanisms to switch off rooftop solar systems brings safety risks, because the high voltages needed exceed the limits that many appliances have safely been tested for.
That’s according to Vince Garrone, former power quality manager at Energex, Queensland’s biggest electricity distributor who called the situation ironic. Authorities, in using “brute force” to trip inverters, were creating the very high voltage conditions the device protection was designed to prevent.
“It’s a bit like having to stop a car by driving into a tree because you’ve not maintained the brakes,” he said.
Aemo’s report noted that South Australia resorted to using the “backstop” almost daily for a week in November 2022 when windy and sunny conditions combined with transmission lines going down, leaving the state unable to export surplus power. Its use helped “ensure there was no repeat” of the 2016 statewide blackout, according to Aemo.
More than 4m Australian homes have rooftop solar systems, the highest rate – at more than a third – in the world. Authorities are adjusting to periods when excess solar power exports pose stability issues for the grid.
Gabrielle Kuiper, a director of the Superpower Institute, says regulators have had years to anticipate so-called minimum system load problems. Alternatives to turning off solar include setting up a market to spur more demand – such as charging batteries – just like big users get paid to power down when power supply is tight.
University researchers are studying how Australia’s relatively high voltages may already be shortening the life of appliances.
Aemo’s report conceded voltage management was “a high risk control” and can result in the “significant impact on customers” including the “reduction in equipment life”. The method was “only suitable for use in rare emergency conditions,” it said.
Garrone said national voltage standards had been relaxed in recent years, permitting a wider range of supply voltage.
However, he highlighted a disparity between the 260 volts or higher likely to be needed to trip inverters against the maximum voltage of 253V to 254.4V used for testing appliances. The devices include residual current circuit breakers (RCCBs) and residual current circuit breaker (RCBO), and products from fans to dishwashers, Garrone’s data showed.
“As far as I am aware, this has not been scientifically demonstrated to be safe and needs to be reconsidered,” Garrone said in a LinkedIn post.
“It only takes one safety standard compliant appliance to catch fire from a high voltage before the risk becomes extreme or catastrophic if there is loss of life,” he said in a response to a reader’s comment.
Garrone had previously detailed at length his concerns smoke detectors were among many appliances that may possibly cease to function as intended if homes were exposed to excessively high voltages.
Guardian Australia approached a range of national and state regulators, distributors, and several smoke alarm makers.
An SA government spokesperson said that state’s Office of the Technical Regulator had not received any complaints about failed or damaged appliances as a result of the use of so-called enhanced voltage management to turn off rooftop solar.
“There is a significant difference between the very high voltages that can be seen during a power surge and the controlled raised voltage used to cause older solar inverters to disconnect safely,” the spokesperson said, noting that most products were tested at 1.06 times the rated voltage.
Victoria’s essential service commission pointed to its public data disclosure. Customers who believe appliances or property had been damaged by a high-voltage event should first contact their electricity distributor. Customers may be able to make a claim for damage.
Dominic Adams, a general manager at Energy Networks Australia, said the country’s distribution networks span more than 850,000km, and that managing reliable connections for 10 million customers was complex.
“Ensuring perfectly consistent voltage with no fluctuations at all times of the day, every day, for every customer would see a large amount of network overbuild which is not economically feasible,” he said.
“Distribution network operators are aware that with increased rooftop solar and a more complex energy system, voltage is increasingly difficult to manage,” Adams said.
“Networks remain responsive to safety-related matters and compliant with their legal, regulatory and technical requirements and obligations.”
One smoke detector supplier said that if its device was used under conditions outside given specifications, “we cannot guarantee that the product will still work properly in the future”.
Similarly, a staffer at another supplier of smoke alarms, said: “[i]f the voltage goes above the tested limits we couldn’t guarantee that the alarm would function/test correctly due to potential damage that may occur.”
Brian Spak, a general manager at Energy Consumers Australia, said networks accounted for about half of a typical power bill and it was their “fundamental job” to provide electricity within appropriate voltage bounds.
“Voltage is not effectively monitored throughout non-Victorian distribution networks today,” Spak said, adding that smart meters could help solve monitoring issues.
“We would like to see an overarching market obligation – such as a duty of care – to ensure that consumers can be confident they will be protected from harm,” he said.
