For some years the system coped well, because plants from the investment boom of the 2000s could be run harder. Coal plants ran at under 60 per cent of capacity in 2016-17 and at about 70 per cent by 2024-25. That was a good use of what had been built. This September there was little slack. In the evenings almost no coal plant that could run was standing idle and, after sunset, supply could not keep up with demand.
Take distribution next. While the data is less precise, we can estimate investment in the distribution network — what discoms spend each year on lines, substations, transformers and other equipment. Figure 2 plots such investment against underlying sales. From 2020-21 to 2022-23, discoms invested about as much each year, after inflation, as they had in the first half of the 2010s, while selling about 50 per cent more power. Even allowing for the uncertainty, we can say that in the last several years, the level of real investment has fallen behind the growth in power that the network has to carry, and even further behind what a modern system geared to incorporating increasing amounts of renewables will require. Investment has picked up since 2023-24, but has not yet caught up.