Eskom's winter numbers put spare capacity, not scarcity, in front of generators.

A generator selling into the South African electricity market now has the utility's own numbers for the room on the system ahead of it. Eskom says it met demand across the whole of the 2026 winter, including on overcast days when rooftop solar output fell away. It counts 476 days in a row without load shedding, from 16 May 2025.

The figures sit in Eskom's weekly system update of 4 September 2026. Its energy availability factor, the share of fleet capacity actually able to run, reached 67.79% for the financial year to 3 September, up from 61.3% a year earlier and, on the utility's account, its best year to date level in six years. Unplanned outages over that period fell to 19.47% of capacity, and average unplanned losses are down by 6 888MW across three years, from 16 097MW to 9 209MW.

Diesel spending between 1 April and 3 September 2026 came to R1.08 billion against R5.93 billion a year earlier, a fall of R4.84 billion or 81.64%, and the load factor on the diesel fired peaking turbines ran at 1.11% rather than 7.92%, inside the 3% annual target. Planned maintenance went the other way: an average of 5 932MW was out deliberately, 12.54% of capacity, up from 5 266MW and 11.23%.

Eskom also reports 6 220MW in cold reserve because capacity exceeds demand, and put the evening peak that day at 22 317MW against 27 576MW available. Assessment: a system carrying that much idle plant and almost no diesel burning prices scarcity differently from one that paid for peaking hours, and the heavier maintenance behind the gain is part of the cost of holding it.

On the customer side, the programme to end load reduction has returned 1 222 430 customers to normal supply, about 72% of the 1.69 million it targets; seven of nine provinces are clear and 6.5% of the customer base remains affected, with national eradication put at March 2027.

For a generator or an offtaker, the question the winter numbers leave open is whether this margin is a level or a peak. The system status update and summer outlook Eskom has said it will release during September is where that starts to show, with the next weekly figures due on 11 September 2026.