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Research and Development  
19 September 2017

SA power system can withstand added RE capacity, says flexibility report

The Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) under the DoE’s South African – German Energy Programme (SAGEN), has published a report that identifies the South African power system to be “sufficiently flexible” to cope with added wind and solar photovoltaic (PV) generation.

“The study presented in this report confirm that the South African power system will be sufficiently flexible to handle very large amounts of wind and PV generation.

“To cope with increased flexibility requirements resulting from the installation of 4,2GW of wind generation and up to 12,8GW of PV by 2020, and 11GW of wind and 27,5GW of PV by 2030, flexibility requirements can be handled by existing and planned power plants at moderate additional costs.,” the report stated.

Flexibility report

The study was performed by international engineering consultants Dr.-Ing. Markus Pöller and Marko Obert, of Moeller & Poeller Engineering GmbH (MPE), for the South African DoE and power utility Eskom.

Published in September 2017, the report is titled ‘Assessing the impact of increasing shares of variable generation on system operations in South Africa – a flexibility study’.

The report presents the methodology and results of a study assessing increased flexibility requirements to the South African power system resulting from increased levels of renewable generation in the time frame until 2030.

The study further analyses whether the existing and planned power plants will be able to cope with these requirements.

Lastly, it quantifies costs associated to increased flexibility requirements imposed by variable renewables (wind and photovoltaic solar).


To ensure secure and cost-efficient operation of the South African power system even with very high levels of wind and PV generation, the author's of the report made the following recommendations:

  • Application of professional short-term forecast tools/ services for wind and PV prediction, including a system for short-term prediction of rooftop PV.
  • In the case of very high PV installations (e.g. 27GW by 2030): Allocation of higher levels of Operating Reserve and Emergency Reserve in afternoon hours.
  • In the case of very high PV installations (e.g. 27GW by 2030): Operate pumped-storage power plants in pumping mode during mid-day (and not during night time) when Residual Load is at its minimum value.

Note: direct excerpts from the Report's executive summary were used to ensure accurate representation. Download the full report here.


Featured image: Stock

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philip lloyd
There are some very strange features in this report. Look at Figures 6 and 7 in the synopsis. Each represents a week of supply/demand balancing. Yet in Figure 6 there are no lows for a Saturday or Sunday, while in Figure 7 there are three days of lows. In both diagrams the morning peak is often higher than the evening peak. I don’t know what they were modelling, but it wasn’t South Africa. These are just some very graphic examples of what is wrong with this report. In short, it is not reliable information, and should not form the basis… Read more »
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