Why Are Mass Rolling Blackouts Occurring? Expert Analysis and ESDM Explanation
Rolling blackouts have begun occurring in several areas on the island of Java. Speculation emerged that the blackouts were caused by reduced coal supply, although this rumour has been denied by the Ministry of Energy and Mineral Resources (ESDM). The Energy Ministry stated the blackouts were merely a technical issue.
The think-tank Institute for Essential Services Reform (IESR) has questioned the initial explanation of a disruption in the electricity system that caused power outages in several regions of Java on 9 and 10 June 2026.
IESR stated that in the Java-Madura-Bali (Jamali) interconnection system, a disruption at one power plant should not easily cause mass blackouts. Mass blackouts can occur if PLN deliberately cuts power to reduce the electrical load (load curtailment).
“In the Jamali electricity system, a disruption at one power plant or one network element should be anticipated through the availability of reserve margin, protection systems, and adequate network redundancy,” IESR said in its explanation.
In PLN’s electricity system, the provision for a reserve margin of up to 30 per cent should provide a guarantee of supply security for power plants. Therefore, IESR is urging the Ministry of ESDM to conduct a thorough investigation to understand the causes, triggering factors, and system weaknesses that allowed the disruption to develop into widespread blackouts.
IESR emphasised that the investigation results must also be conveyed to the public as a form of accountability. According to the think-tank, the Jamali blackouts also need to receive attention from President Prabowo Subianto. This is because it impacts energy security, competitiveness, and economic losses for the business world and the public.
“The rolling blackouts that have occurred over the last three days have financially harmed consumers. Although consumers are entitled to compensation, the value of that compensation is not comparable to the costs and losses incurred due to the power outages,” said IESR Chief Executive Officer (CEO) Fabby Tumiwa on Thursday (11/6/2026).
Low fuel reserves
IESR suspects the recent rolling blackouts were triggered by low fuel reserves at several coal-fired power plants (PLTU) in the Java-Bali system, forcing them to operate below optimal capacity. The limited coal supply caused the Plant Operating Days (HOP) to fall below safe limits. Similarly, plant disruptions, such as those that occurred at the Jawa 1 Gas and Steam Power Plant (PLTGU), reduced the electricity supply.