South Africa’s ongoing energy crisis is driving rapid and meaningful regulatory change which in turn is stimulating development of renewables, particularly for the Commercial and Industrial (C&I) sector. But wind and solar resources are distributed by nature making co-location of generation with demand challenging. To address this, ESKOM, the national system operator, provides a ‘wheeling’ service enabling solar and wind generators to move power over the transmission system to where it is needed.

A market opportunity has emerged for organisations to match generation capacity with off-taker demand and to enable the required transmission through management of the wheeling arrangements. These energy brokers aim to match a portfolio of generation capacity on the supply side with a portfolio of off-take load on the demand side. This means that they must manage volume and shape risk on the supply side and demand for baseload power on the consumption side. 

Our energy experts recently worked with a South African based power trading company to provide deep dive solar and wind yield analysis and strategic modelling support to help balance demand and supply risk.


Our client already had an industry standard yield assessment for a large solar facility providing supply capacity. Our work focused initially on demonstrating the potential to supplement industry standard yield analysis with deeper, commercially relevant insights into the expected production and how well it fits with complex demand.

We used a 10-year weather simulation, downscaled to a spatial resolution of 1km and a temporal resolution of 10 minutes as input to our proprietary modelling applicaton, EnergyMetric. EnergyMetric converts weather to power for any combination of solar and/or wind installations. 

By basing our production analysis on a longer time series of weather data (the industry standard approach provides a 12-month simulation) we unlock the potential to explore variability in a lot more detail.

We exposed inter-annual variability and trends in seasonality. We were also able to show what low production, high production and average production look like within each month, considering the full 10-year weather simulation. EnergyMetric also quantifies uncertainty, providing exceedance probabilities on production metrics across all timescales and statistical uncertainties on all graphical outputs. Our client now had access to:

  • Deeper understanding of the potential for production to vary from year to year,
  • more detailed understanding of trends in within-year seasonality,
  • quantitative insights into what good, bad and average production looks like, and
  • the ability to understand and exploit exceedance probabilities.

With EnergyMetric we can also provide demand comparisons. By integrating an aggregaged demand profile into the analysis we can show how well the production profile fits with the consumption requirements from multiple off-takers, exposing and quantifying periods of residual or excess generation.

To improve things further we extended our initial yield-focused analysis to include a demonstration of potential to inform decisions about how best to grow the supply side portfolio. We did this using EnergyMetric to explore production potential from a range of solar and wind locations, in different combinations and considering different off-take requirements.


The additional insights improved on industry standard yield analysis, enabling our client to increase the sophistication with which they manage volume and shape and increasing their confidence in implementing mechanisms to improve returns.

Our correlation analysis into building out the supply side portfolio provided quantitative evidence to clarify questions like:

  • How well does solar combine with wind?
  • Are 2 large installations better than 1 large and 2 small?
  • Which combination of technologies and locations maximises diversity?

By the end of the initiative our client had a detailed understanding of how industry standard yield analysis could be enhanced and how EnergyMetric could inform strategic decisions on the best way to grow their business.

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