South African electricity planning · 2008–2025
Every plan forecast growth but (shock) demand fell.
Nine national demand forecasts, from Eskom's ISEP12 in 2008 to IRP 2025, drawn against what the grid actually delivered. Growth assumptions have come down since 2010, yet every forecast old enough to be tested has overshot. Actual demand in 2025 was 14% lower than in 2010.
How to read it
Rebased to actual scales each plan so it starts at measured demand in its base year (the last year of data it could have used, marked with a dot), then follows the plan's own growth. This isolates forecasting error from the definitional gaps between documents.
As published shows each plan's own numbers. Most IRPs use national net sent-out, which runs 7–16% above Stats SA's figure; the hollow markers show the base-year demand the plans themselves state.
Definitions
Actual: Stats SA P4141, electricity available for distribution, calendar year (generation less own use and pumping, plus imports, less exports). It excludes rooftop PV, which displaced roughly 10 TWh a year by 2025, and it is depressed by load shedding in 2008 and 2019–2023.
ISEP12 is Eskom national plus foreign sales, excluding losses. Draft IRP 2016 is shown through its CSIR Annexure B forecast. IRP 2018, 2019, 2023 and 2025 values are digitised from the plans' charts (±1–1.5 TWh).
Sources
Government Gazettes 32837 (IRP1), 34263 (IRP 2010), 42784 (IRP 2019), 49974 (draft IRP 2023) and 53596 (IRP 2025); IRP Update 2013; draft IRP 2016 Annexure B and CSIR 2017 demand forecasts; draft IRP 2018; ESRG/SANEDI demand projection (2023); IRP 2010 input sheet D1 (ISEP12); Stats SA P4141. Full source list in the accompanying workbook.