BusinessDayTV Sep 22, 2026
With Dan Ginsberg, Executive Director of Discovery Green
A renewable energy contract sized to one expected output figure can leave a business with three times the power it planned for, or none at all, Dan Ginsberg said.
South African companies have been moving to renewable power to escape an unreliable grid. Ginsberg's point is that the move carries its own risk: the output of the plant and the buyer's own demand both swing far more than the contracts assume.
"So the volatility of outcomes is enormous."
Dan Ginsberg, executive director of Discovery Green, the renewable energy arm of South African financial services group Discovery, spoke to Business Day TV about EnergyOS, the platform Discovery Green has just launched. He said it applies Discovery's actuarial methods to renewable power.
The full interview is covered here so you can skip it.
Here are the 5 insights that matter.
Key Takeaways
The industry prices renewable power off a single mid-point estimate, which Ginsberg said is where the risk lies
Planned output of 100 units can turn out to be 300 or zero, and the buyer's own demand can be just as wrong
EnergyOS runs 3 connected models: forecasting, retail product design and portfolio allocation
5 years of proprietary data feed a system that compares actual results with expected ones, as an insurer does
Discovery Green says this is the first time the approach has been applied to renewable energy in South Africa
1. Why a P50 Misleads
The Business Day TV presenter set up the segment. South Africa's economy has lost billions over the past decade because of insufficient power supply, although Eskom, the state utility, has since improved, the presenter said, and companies have been moving to renewable energy. The question put to Ginsberg was whether a renewable energy plant could hurt a company's bottom line because of a miscalculation about what it actually needs.
"It all boils down to things are not always how they seem to be." — Dan Ginsberg
The industry works from a single estimate
The industry works from fixed assumptions, he said, "and this is where the perils lie." The main one is the P50, a single mid-point estimate of what a renewable energy plant will produce.
He gave an example. A buyer is told a solar plant will typically deliver 100 units of energy a year. The buyer checks last year's consumption, finds it was 200, and plans how the 100 fits into the 200. But the sun shines very differently from year to year, month to month and hour to hour.
"So the 100 you thought you were going to get from renewable energy could be 300, or it could be zero." — Dan Ginsberg
Demand moves too
The 200 can be just as wrong, he said. A company's demand shifts with events in its industry, with GDP, and with shocks such as COVID and load shedding, South Africa's rolling power cuts.
"Your signature of demand is going to change." — Dan Ginsberg
The presenter added that wind is part of the mix as well, and that the sun goes down and the wind changes. Ginsberg agreed that both change all the time.
