GridPulse ZA
South Africa's electricity, hour by hour
National demand
–MW
Supply mix now
Renewables share
–%
Carbon intensity
–gCO₂/kWh
Net exchange
–MW
Unplanned outages
–MW
Where South Africa's electricity comes from. Pumping and exports sit below zero, the dark line is national demand, and red crosses along the bottom mark load reduction.
Since April 2022
Estimated grams of CO₂ per kilowatt-hour supplied (see method notes below).
Average this period – gCO₂/kWh
Wind and solar PV generation stacked on each other. The thin line shows the installed capacity of the two fleets combined.
Eskom's demand forecast implies how much wind and solar it expects each hour. Comparing that with what actually arrived shows how predictable the renewable fleet is.
Energy cut by load shedding each month, across the whole record, whatever dates are picked above. This counts Eskom manual load reduction only, so contracted industrial curtailment is not mixed in.
What each band in the stack means
The backbone of the system: a dozen large coal stations, mostly on the Mpumalanga coalfields, still supply roughly four-fifths of South Africa's electricity. The fleet is ageing, and unplanned breakdowns are the main driver of supply shortfalls.
Koeberg, near Cape Town, is Africa's only commercial nuclear power station. Its two units (about 1.9 GW combined) run as steady baseload, and a life-extension programme is under way to keep them running into the 2040s.
Open-cycle gas turbines at Ankerlig, Gourikwa and IPP plants burn diesel to cover evening peaks and emergencies. They are flexible but very expensive to run, so a tall red band usually means the grid is under strain.
Ingula, Drakensberg and Palmiet (about 2.9 GW) act as the grid's giant batteries. They pump water uphill when demand is low, which is the band below zero, and generate at the morning and evening peaks.
Independent producers, mostly in the Cape provinces, feed in a growing fleet of wind farms and solar parks. Solar PV makes the midday hump; CSP plants store heat and keep producing into the evening.
A high-voltage DC link brings hydropower from Cahora Bassa in Mozambique, and South Africa trades with its neighbours through the Southern African Power Pool. Imports add to supply, and exports appear below zero.
Coal still does most of the work, usually around four fifths of generation. The rest comes from Koeberg nuclear, a growing fleet of wind and solar farms, hydro, pumped storage and imports. The live stack at the top of the page shows the grid mix for the latest hour, and the % share view shows how it shifts during the day.
Over a full year coal supplies roughly 80% of South Africa's electricity. Its share is highest overnight and in winter, and drops on sunny, windy middays. Switch the generation stack to % share to watch it move.
SAWEM is the competitive wholesale electricity market South Africa is introducing as the power sector unbundles, with the National Transmission Company of South Africa (NTCSA) as market operator. Any market needs transparent grid data, and GridPulse ZA tracks the physical side of it: generation by source, national demand and the energy mix, every hour.
Everything is calculated from public hourly data on the Eskom Data Portal: generation by source, demand, imports and exports, outages and installed capacity. Carbon intensity is an estimate, and the method notes list the emission factors used.
Yes. When Eskom sheds load it shows in the Right now panel and as red markers along the generation stack. That count uses manual load reduction only, so contracted industrial curtailment is not reported as load shedding. Heavy use of diesel peakers and pumped storage in the stack is another sign the grid is under strain.
Over the last year Eskom's demand forecast implied about 5% more wind and solar than the fleet actually delivered, missing by roughly 400 MW in a typical hour. Their demand forecast is far tighter, within about 2% of actual demand. GridPulse ZA compares the two hour by hour on the forecast accuracy chart.
The toughest stretch in this dataset runs through 2022 and 2023, when breakdowns in the coal fleet forced record levels of load shedding. The load shedding history chart on this page shows every month since April 2022, so you can see the crisis build and then ease off.
Spotted something odd in the data, want a chart that is not here yet, or just want to say hello? Write it here and it comes straight to us.
GridPulse ZA is an independent, non-commercial project that shares public data and knowledge on South Africa's electricity mix. All figures are calculated from data that Eskom publishes. The site is not affiliated with, or endorsed by, Eskom.
The electricity mix is simply the combination of sources keeping the lights on at any given hour: coal, nuclear, wind, solar PV, concentrated solar, hydro, pumped storage, diesel peakers and imported power from the Southern African Power Pool. GridPulse ZA tracks that mix hour by hour since April 2022, next to national demand, the carbon intensity of every hour and the full record of load shedding, so anyone can see how the South Africa electricity mix is actually changing. The project takes its inspiration from RTE's éco2mix in France.