AEMO wants better inverters, and ability to shut down rooftop solar, as penetration grows to 50%

The Australian Energy Market Operator has confirmed that it will be seeking improved inverter standards for new rooftop solar PV systems, to help it gain more visibility over the increasing rooftop solar pie, and give it the ability to “curtail” rooftop solar output when needed.

The warnings came in the release of the long-awaited Renewable Integration Study, that lays out what’s needed to manage Australia’s rapidly changing energy grid, and help AEMO deal with up to 75 per cent instantaneous wind and solar penetration that is likely to occur before 2025.

Rooftop solar is a major part of this occasion, because it is already contributing up to 50 per cent of instanenous demand across the grid – up to 64 per cent in South Australia – and will contribute up to 85 per cent of instant demand by 2025 in that state.

The push to new inverter standards – which will provide more “connectivity”, and give AEMO more visibility, and the ability to “curtail” output when necessary _ has been well flagged, and is included in Western Australia’s ground breaking Distributed Energy Roadmap, which was done in consultation with the market operator.

In W.A., rooftop solar has already become the largest single generator on the grid, overtaking coal and gas, and causing steep “ramping” issues as rooftop solar output declines in late afternoon, just as grid demand increases.

The issue is also being felt in South Australia, and will soon be followed by other states, and within five years rooftop solar could be providing 50 per cent of demand across the main grid at times. (See graph below).

“Urgent changes to improve the performance of DPV (distributed rooftop solar PV) fleet in response to disturbances, improved compliance with standards, and a level of real-time visibility and curtailability of the DPV fleet will all assist with managing these challenges in South Australia,” AEMO says in its report.

“Over the next five years, other NEM regions are projected to enter similar operating zones as South Australia today.

“Based on the South Australian experience, implementing these changes for new DPV systems nationally, in anticipation of high penetration in other regions, would assist with securely integrating the future DPV fleet with the needs of the power system.”

As dramatic as they sound, AEMO insiders insist that the problem is relatively easily solved – as long as the new inverter standards are introduced. AEMO has also flagged that it could be applied retrospectively to existing systems, although it is not clear how it can be done.

Supporters say that while the ability to constrain rooftop solar output might be dramatic, it would likely happen only rarely – and at times of traditionally low demand such as spring, autumn and weekends. They say it is a better option than having arbitrary output limitations that impose export limits all year long, even at times when such limits are not necessary.