The brand new commonplace for solar inverters took off when AEMO pushed for stricter controls – One Step Off The Grid

The call for tough new inverter standards for controlling rooftop solar systems, battery storage and charging electric vehicles started in 2021 after an update from Standards Australia was carried out a week before Christmas 2020.

The Australian standard AS / NZS 4777.2 Grid Connection of Power Systems via Inverters, Part 2: Inverter Requirements, was published by SA on December 18 after accelerated consultation and industry development.

The updated standard stipulates that all new inverters connected to the national electricity market must have a through-voltage fault for undervoltage faults, which essentially ensures that they can withstand grid faults and do not jeopardize grid reliability through an uncontrolled shutdown.

Standards Australia delivered the update less than 18 months after its request from the Australian energy market operator, which is the speed of light in the world of electricity market reform. As AEMO said in a welcome statement, this is a "significant achievement" given the complexity of the proposed changes.

As RenewEconomy reported in early December, AS4777.2 shouldn't go into effect until the second half of 2021 – or about six months after a final ruling is set, which is expected to take place in February.

According to AEMO, about two months ahead of the scheduled date, the release "highlighted the importance of cross-industry collaboration to respond to the rapid developments the energy industry needs during its current transition."

"Our challenge is to facilitate and manage the transformation of the energy system while delivering affordable, safe and reliable energy to all Australians," said Violette Mouchaileh, AEMO's chief member services officer.

"Industry standards as well as political and regulatory frameworks must adapt to the changing demands of the power grid in order to support a safe and reliable network that delivers affordable electricity to consumers," she said.

For the rooftop solar industry, however, the speed of the decision points to big – and much more controversial – changes.

As RenewEconomy has reported, the AS4777.2 update differs from the recently enforced rules in South Australia in that solar households do not have to designate an "agent" to switch off their solar energy if the market operator requests it.

But that is also on AEMO's wish list for NEM-wide inverter standards, since distributed energy resources such as PV on the roof must be at least twice as large by 2040.

In fact, in addition to the update of AS4777.2, the market operator had already requested the addition of a minimum technical standard for interoperability and communication interfaces and cybersecurity measures, as well as for inverter performance and grid reactivity.

However, in a draft declaration in early December, the Australian Energy Market Commission initially called for focus on making drive-through inverter standards the top priority for a rapidly changing grid.

"What we're doing with this rule change is putting something into effect," said David Feeney, AEMC's Executive General Manager, Transmission and Distribution Networks, in an interview with RenewEconomy. "South Australia had the most pressing need and now we are catching one of the most pressing problems for the rest of the market."

Meanwhile, AEMO has signaled that it will continue to make major efforts to improve the visibility and control of solar inverters, including the ability to completely disconnect them from the grid under certain circumstances.

"AEMO's next standards priority will be to further develop the interoperability functionality of inverters, expand device functionality to enable remote output management, query and change device settings, and various options for coordinating DER," said the Declaration in January.

"This will enable improved network management and the development of new retail options by retailers to enable consumers to customize and optimize their energy services while opening up new opportunities to increase their return on investment."

However, the question for the rooftop solar industry for now is how quickly the new standard will come into play.

The AEMC had proposed a start date for September for all AS / NZS 4777.2: 2020, while the Clean Energy Council is pushing for a later date, December 18, 2021, but the implementation of the new short period of tension through the testing process could already be on March 31st.

"The AEMC should mandate the Short Duration Undervoltage Ride Through (SDUVRT) testing process earlier than the proposed six months and AS / NZS 4777.2: 2020 no earlier than twelve months after publication," KEK said in its filing with the AEMC.

"The manufacturers of inverters want the full twelve months for the implementation, because according to AS / NZS 4777.2: 2020 the manufacturers have to make significant changes to the hardware and software of the inverters, followed by tests and certifications," it continues.