New solar inverter standard rushed through, as AEMO pushes for tighter controls

The push for strict new inverter standards to control rooftop solar systems, battery storage devices and electric vehicle charging, has hit the ground running in 2021 after an update from Standards Australia was rushed through a week before Christmas in 2020.

The Australian Standard, AS/NZS 4777.2 Grid connection of energy systems via inverters, Part 2: Inverter requirements, was published by SA on December 18, after an accelerated industry consultation and development timeframe.

The updated standard will make it mandatory for all new inverters connecting to the National Electricity Market to have an undervoltage disturbance ride-through capability, which essentially ensures they can withstand network faults and not put grid reliability at risk through an uncontrolled shutdown.

Standards Australia has delivered the update less than 18 months after it was requested by the Australian Energy Market Operator, which is tantamount to light-speed in the world of electricity market reform. As AEMO put it in a statement welcoming the news, it’s a “significant achievement, given the complexity of the changes proposed.”

As RenewEconomy reported in early December, AS4777.2 was not expected to come into effect until the second half of 2021 – or roughly six months after a final rule was made, which was expected to happen in February.

AEMO says its publication roughly two months ahead of schedule has highlighted “the importance of collaboration across industry to respond to the fast-paced developments required by the energy industry through its current transition.”

“Our challenge is to facilitate and manage the transformation of the energy system, while continuing to deliver low-cost, secure and reliable energy for all Australians,” said the AEMO’s chief member services officer, Violette Mouchaileh.

“Industry standards as well as policy and regulatory frameworks must adapt to the changing needs of the electricity grid, to support a secure and reliable network that delivers affordable electricity to consumers,” she said.

But for the rooftop solar industry, the speed of the decision suggests huge – and much more controversial – changes ahead.

As RenewEconomy has reported, the AS4777.2 update differs from the rules recently rushed through in South Australia in that it does not require solar households to nominate an “agent” to switch off their solar if asked to by the market operator.

But that, too, is on AEMO’S wish-list for NEM-wide inverter standards, as it braces for distributed energy resources like rooftop PV to at least double in capacity by 2040.

In fact, the market operator had already requested, alongside the update to AS4777.2, the addition of a minimum technical standard to cover interoperability and communication interfaces and cyber security measures, as well as inverter performance and grid responsiveness.

But in a draft determination in early December, the Australian Energy Market Commission made the call to focus, first, on bedding down the ride-through inverter standards, as the highest priority for a rapidly changing grid.

“What we’re doing with this rule change is getting something in place,” said the AEMC’s executive general manager of transmission and distribution networks, David Feeney, in an interview with RenewEconomy at the time. “South Australia had the most pressing need, and now we’re playing catch-up on one of the most urgent issues for the rest of the market.”

AEMO, meanwhile, has signalled that it will continue to push hard for greater visibility and control over solar inverters, including the ability to disconnect them from the grid completely in certain circumstances.

“AEMO’s next priority for standards will be to further develop the interoperability functionality of inverters, expanding device capabilities to allow remote output management, querying and changing device settings, and various options for coordination of DER,” the statement in January said.

“This will allow improved network management and development of new retail options by retailers to provide consumers the ability to individualise and optimise their energy services while opening up new opportunities to increase their return on investment.”

For now, however, the question facing the rooftop solar industry is how quickly the new standard will be brought into play.

The AEMC had proposed a September start date for all of AS/NZS 4777.2:2020, while the Clean Energy Council is pushing for a later date of 18 December 2021, but with the implementation of the new short duration under voltage ride through test procedure could as early as 31 March.

“The AEMC should mandate the short duration undervoltage ride through (SDUVRT) test procedure earlier than the proposed six months and should mandate AS/NZS 4777.2:2020 no earlier than twelve months after publication,” the CEC said in its a submission to the AEMC.

“Inverter manufacturers want the full twelve months for implementation because AS/NZS 4777.2:2020 will require manufacturers to make substantial modifications to inverters’ hardware and software, followed by testing and certification,” it said.