Wind and solar smash grid market share records, even after heavy curtailment, coal at new low

Wind and solar energy smashed their market share records on Saturday, even after heavy curtailment that dragged back their potential output from meeting more than 113 per cent of grid demand to just below 80 per cent.

According to GPE NEMLog, the share of renewables hit a new peak of 79.8 per cent at 11 am (AEST) on Saturday, courtesy of strong winds affecting southern Australia, and the new found ability of some big coal units to dial down their output significantly, or even switch off altogether.

According to GPE’s Geoff Eldridge, the share of variable renewables – large scale wind and solar and rooftop PV – reached a new peak of 77.1 per cent, beating the previous record of 75.9 per cent in late September.

What is more remarkable is that the peak was reached mostly with rooftop solar, which more large scale wind and solar curtailed rather than actually delivered to the grid – most likely due to economic reasons because of negative wholesale prices, but perhaps also due to network constraints.

The curtailed wind and solar alone accounted for around one third of underlying demand, meaning that the “potential” share of renewable was more than 113 per cent at the time – also a record.

The Australian Energy Market Operator has said that it is preparing for the day when it is able to manage the grid with up to 100 per cent instantaneous penetration of renewables.

It had hope to be able to deliver that by 2025, but it appears that not all its engineering ducks have been lined up – it most likely needs more synchronous condensers, and grid forming batteries, that will together supply the “system strength” normally provided by coal fired generators.

And it is doubtful that the owners of some coal fired generators will want to switch them off completely. Some of them now can, and do, which led to a record low share of coal of just 20.4 per cent around the same time.

Some coal generators have learned to flex to just 20 per cent of their rated output to dance around the impact of rooftop solar, and AGL has been “two-shifting” one of its units at Bayswater – switching them off for a whole “shift” in the middle of the day – as it appears to have done again on both Friday and Saturday.

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