Paks outage dramatically reshaped Hungary’s power mix

Solar power appeared to transform Hungary’s electricity mix after production at the Paks nuclear plant fell sharply. Its share rose from 36% to 51%, meaning solar supplied more than half of domestic generation during the week examined.

That percentage, however, can be misleading. Solar output increased by only 6%, adding 81.1 megawatts. That covered barely 7% of the 1,132.2 megawatts of nuclear generation lost at Paks. The solar share grew mainly because total domestic generation contracted by 945.5 megawatts.

Gas power shows the same denominator effect. Average gas-fired generation slipped only from 584.5 to 575.5 megawatts, a decline of 9 megawatts, yet its share of the mix rose from 15% to 20%.

The immediate explanation in summer is straightforward: prolonged heat and a lack of rain lowered the Danube’s water level, directly limiting the plant’s access to cooling water. Winter would remove the heat factor, but river flow can also fall during prolonged freezes if precipitation remains locked in the watershed instead of flowing into the river. The available summer data cannot show how likely a winter shortage would be to reach the level that reduced Paks output.

The 1,132.2-megawatt loss illustrates the system-wide risk of concentrating Hungary’s nuclear capacity at one site and partly relying on one river’s flow. The new units being built under Paks II are intended to reduce that exposure. With greater total capacity, a similar outage would represent a smaller share of the system and leave it less dependent on the momentary condition of one plant.