In recent days we’ve already written:

1)  Several articles about a notable Frequency Spike at 10:30 on Friday 10th April 2026:

(a)  which appears to be due to some glitch in UIGF forecasting at the AEMO

… possibly compounded by some ‘Games that Self-Forecasters can Play’.

(b)  and led to frequency spiking up outside the Normal Operating Frequency Band for a Dispatch Interval.

2)  And we’ve also published two articles about an eerily similar Frequency Spike at 14:20 on Saturday 11th April 2026 :

(a)  which appears to have been due to very similar cause

(b)  this is the third article about this event.

There are 115 x Semi-Scheduled Solar Farms and 86 x Semi-Scheduled Wind Farms currently in AEMO’s data systems.

… so all up that means 201 x Semi-Scheduled units (both Wind and Solar) across all regions of the NEM.

Dispatch Error for all 201 units at 14:20

In this article we’ll look specifically at calculated Dispatch Error for the 14:20 dispatch interval (NEM time) on Saturday 11th April 2026 – starting with the 115 x Solar Farms:

Remember that you can click on a chart for a larger resolution image in another tab that might enable you to read the DUIDs … though you might need to squint, as we used a small font to fit them in.

As noted on the image:

1)  There were 10 x Solar Farm units that each:

(a)  had over-performance (relative to Target) larger than 25MW

(b)  i.e. Dispatch Error < -25MW

(c)  Of these 10 units, 4 showed discrepancy larger than 50MW

2)  On the flip side, there was only 1 x Solar Farm with under-performance that large (i.e. larger than 25MW).

3)  So clearly an imbalanced dispatch

…. which is particularly notable because (as Allan described well here) the one-sided nature of the Semi-Dispatch Cap means large under-performance (ordinarily!) is much more common.

4)  These units were in various regions.

Next we’ll do the same for the 86 x Wind Farms:

With this image:

1)  Note that the same y-axis step of 25MW has been used, for consistency

… this shows that the higher exceedances were higher for Wind Farms than for Solar Farms

2)  We see that there were 12 x Wind Farm units that each:

(a)  had over-performance (relative to Target) larger than 25MW

(b)  i.e. Dispatch Error < -25MW

(c)  Of these 12 units, 8 showed discrepancy larger than 50MW

2)  On the flip side, there was not a single Wind Farm with under-performance that large (i.e. larger than 25MW).

3)  These units were in various regions.

Across all 201 units … some head scratching results

Summing up, across 201 units:

1)  There were 22 units with over-performance greater than 25MW;

2)  Which is a staggering number:

(a)  That’s ~10% of all Semi-Scheduled units!

(b)  That’s 22 times the number of units with under-performance greater than 25MW;

(c)  Which is even more notable because (as Allan described well here) the one-sided nature of the Semi-Dispatch Cap means large under-performance (ordinarily!) is much more common.

3)  Surely it’s causing some head-scratching, with concerns about system stability?