Too Much Solar Power in South Australia

By Paul Homewood

Overload in Australia!


“Give us more load. And, please, switch off that rooftop solar.”

These are not instructions you hear every day, but they have been the “cri de coeur” from Australia’s Energy Market Operator this week as it battles to deal with a South Australia grid isolated by storms from the rest of the market, and one of the world’s highest penetrations of rooftop solar.

AEMO has ordered local authorities to switch off as much rooftop solar as they can, and encourage as much electricity use as possible, as it seeks to create enough “load” to give it control of a grid that fears could spin out of control if struck by another major event.

It’s quite the turnaround for the state’s solar households.

It was only a few weeks ago that SA Power Networks, which owns the local poles and wires in South Australia, was boasting of a fantastic new achievement – rooftop solar had met all local demand for more than five hours in a row in the middle of a sunny Saturday.

It was indeed, a major milestone, and a sign of things to come: This is the state with the largest share of wind and solar of any gigawatt scale grid in the world – 66 per cent of local demand in the last 12 months. And rooftop solar is a major part of that.

It is also a sign that Australia’s grid is rapidly changing from a centralised, fossil fuel-based system to a renewable and increasingly distributed grid. Consumers are now producers too, and rooftop solar is chasing base-load coal and other fossil fuels out of the grid.

This week, though, SAPN had to temporarily change its tune, and has been desperately trying to cut off as much rooftop solar as it can, by sending signals over wi-fi, tripping inverters through increased voltage, and sending out public pleas for customers to switch off their rooftop solar systems, and switch on anything they can.

What has changed?

When rooftop solar reached more than 100 per cent of local demand in late October it wasn’t a problem because the grid in South Australia was connected to Victoria and could send excess power to its neighbour.

That meant there was still enough “load” in the grid, and AEMO could use a small amount of gas generation for grid security and be comfortable in the knowledge that it had enough leg room and levers to deal with any unexpected events.

The storm that blew through South Australia last Saturday afternoon changed all of that. It tore down one transmission tower, triggered a trip in multiple circuits and “separated” the state grid from the rest of the National Electricity Market.

The state is now on its own, and large amounts of rooftop solar threaten to become more of a liability than an asset, because if rooftop solar can meet all or most of local demand, it would leave few or no levers for AEMO to pull if another major incident affects the grid.

Which is why the call went out from AEMO at the start of the week to “Give Us More Load.” It asked major energy users to turn on whatever they could during the middle of the day and called on SAPN and the state government to switch off small solar farms.

The article tries to dismiss this problem as one caused by the storm which broke the connections to Victoria. But this is to dismiss the fundamental issue.

Intermittent energy can only be integrated in a grid where there is sufficient dispatchable power to provide stability – both to make up for shortfalls and to turn down when renewable output is high.

South Australia relies on the grid connections to Victoria and beyond to provide that stability. In 2021, only 22% of Australia’s electricity came from renewables, so the country as a whole had plenty of dispatchable power to manage the intermittency.

But in the renewable future mapped out by the Labour Government, the whole country will become like South Australia. And where then will the country offload its surplus power?


November 18, 2022

Too Much Solar Power In South Australia — NOT A LOT OF PEOPLE KNOW THAT