Wind and Solar PV Resource Aggregation Study for South Africa

The ‘Wind and Solar PV Resource Aggregation Study for South Africa’ was carried out to increase the fact base and understanding of aggregated wind and solar photovoltaics (PV) power profiles for different spatial distributions of these renewable energy sources throughout the whole country. Potential to generate electricity from wind and solar PV energy was determined based on data sets for five years covering the whole country with a spatial resolution of 5 km by 5 km and a temporal resolution of 15 minutes. Aggregation effects were investigated for a number of geographical distribution scenarios with varying penetrations of solar PV and wind energy.
The primary findings of the study include the following:

  • The wind resource potential is as good as the solar resource. Almost the entire country has sufficient resources with potential for very high load factors and, thus, profitable wind projects. It is possible to generate significantly more electricity from wind and solar PV energy than what is needed by the country even when considering spatial exclusion zones.
  • While the solar irradiation and electricity generation from solar PV shows nearly no seasonality, wind speeds and generation from wind closely follows the demand over the year. In addition the diurnal characteristics of wind feed-in complement the solar PV peak by showing a minimum at noon. Those complementary effects enable the integration of wind and solar PV power into the grid to a great extent.
  • As determined in [1], at least 20% overcapacity of wind and solar PV power can be installed per substation without any curtailment of wind and solar PV power.
  • Gradients of the electricity feed-in from wind generation can be reduced noticeably through aggregation effects (more distributed wind turbines result in reduced fluctuations). A wider distribution of turbines also leads to a significant reduction of forecast errors.
  • Finally, up to 20 to 30% energy share of variable renewable energies (wind and solar PV) for the whole country will not increase short-term (15 min) gradients or ramps significantly if there is a balanced combination of wind and solar PV in the electricity system.

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