Page 55 - Energize October 2022

VIEWS AND OPINION

the actual performance of the installed wind and solar fleet during the load shedding both higher and lower than these figures.
period. The approach that will be adopted will be to try and answer the question of what The worst-case conditions shown in the
would have happened had additional RE been installed, during this period. graph are not unique nor unusual, but
The installed wind-powered fleet consists of around 30 wind farms comprising occur regularly. In particular, low solar
1300 turbines totalling around 3300 MW located around the country, and the solar performance is due to country-wide
PV fleet consists of around about 70 solar farms totalling around 2000 MW. CSP cloud cover, which occurs regularly,
systems will not be included as they require direct sunlight to operate and do not as shown in Figure 3. This is identified
produce any output during overcast or diffuse sunlight conditions. (This can be seen on the graph by the disappearance of
from the graph).
It is unknown whether Eskom took the performance of wind and solar into
consideration when declaring the various stages of load shedding, although one media
article claimed that several consecutive days of continuous high wind performance
prevented Stage 7 load shedding, but the plain point of view is that such a move would
involve high risk.
The starting point of this study will be the performance of the renewable fleet during
the recent load shedding. While most RE reports focus on average and high-performance
records, this study will focus on low performance, particularly severely low performance,
as this is what will cause network failure, and has the greatest effect on the ability to
combat load shedding.
Figure 1 shows the recorded aggregated hourly average performance of all wind and
solar systems connected to the grid for the months of May and June 2022. Figure 2 shows
the same data for the months of June and July.
It is useful to note that these are hourly averages, and instantaneous values were

Figure 1: Renewable energy hourly data for May and June 2022 (Eskom)

Figure 2: Renewable energy hourly data for June and July 2022 (Eskom) Figure 3: Satellite images of cloud cover (Sat 24)

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