Bulgaria has reached a new milestone in restoring the Chaira pumped-storage hydropower plant, with Unit 3 cleared for commercial operation after completing regulatory and technical approval procedures. The National Electricity Company (NEK) said the unit received its final operating permit following an inspection by the state commission. The approval indicates that the rehabilitation works satisfy technical, construction, and legal requirements, enabling the facility to return to regular service.
NEK’s announcement also states that certification completes the recovery process for Unit 3. Inspectors confirmed that the refurbishment was carried out according to approved engineering plans and in compliance with applicable standards. This clearance is described as another step in the gradual restoration of HPP Chaira toward full functionality.
Role of HPP Chaira in Bulgaria and the Balkan power market
The HPP Chaira site supports Bulgaria’s electricity system and the broader Balkan power market, according to NEK’s statement. It is described as the largest pumped-storage hydropower plant in the region. The facility provides balancing and flexibility services intended to help stabilize electricity systems with increasingly dynamic conditions.
The plant had been largely offline for several years after unsuccessful repair work led to the shutdown of its generating units. NEK said the current restoration effort is aimed at bringing additional capacity back into service. The return of further capacity at Chaira is expected to strengthen Bulgaria’s ability to balance renewable energy production.
Restoration plans for Units 1 and 4
NEK continues restoration activities across remaining units at HPP Chaira. Work on Unit 1 is being performed by Japan’s Toshiba Corporation under an agreed rehabilitation schedule, with completion expected in 2028. Preparations are also underway for recovery of Unit 4.
The utility links the staged return of capacity to improved grid reliability and enhanced overall energy security across the region. NEK’s statement places Unit 3’s commercial clearance within a broader program covering Units 1 and 4.
