The 2025 Sri Lanka Nationwide Blackout

At 11:13 on Sunday 9 February 2025, a phase to phase to earth fault hit the 33 kV bus section at the Panadura grid substation, pulling voltage down by 40% at the 132 kV level. Protection cleared the fault in 1.1 seconds, as designed, but system frequency kept falling, from 50.12 Hz to 49.5 Hz within 5.5 seconds. Public statements on the day pointed to an animal that had fallen on equipment at the substation.

All five stages of automatic load shedding for low frequency operated and could not stop the fall, and about 22 seconds after the fault the system collapsed as the main generating units tripped. The regulator, the Public Utilities Commission of Sri Lanka, found no evidence of a major generator failure in the first 5.5 seconds. It pointed instead to weak frequency response in a low inertia grid: about 77 MW of rooftop solar disconnected as voltage dipped, the unit designated to control frequency raised its output by only 4 MW, and the load shedding scheme, last updated in 2018, was blunted by more than 1,000 MW of rooftop solar added to distribution feeders since.

The grid was down for about 4.5 hours, leaving 5.5 GWh of demand unserved, and rotational power cuts then continued for four days, taking the total unserved demand to 10.1 GWh. The regulator's recommendations include routine checks of rooftop inverter settings, faster governor response and load shedding that accounts for rooftop solar, and a government gazette has since issued binding directions to all electricity licensees.