Chaira

Chaira pumped hydro overview.

Chaira is an underground pumped storage power station in Bulgaria’s Rila mountains, forming part of the Belmeken–Sestrimo–Chaira cascade. NEK is restoring its four reversible generating units in stages. Unit 3 returned to service in April 2026, while further work on the remaining units forms part of the station’s longer-term restoration programme.In OperationBulgaria

At a Glance

Declared capacity

420 MW

Energy storage

Data coming soon

Operator

Data coming soon

Country

Bulgaria

Location

42.159°, 23.871°

Website

Official project page

Ownership

2 records

Share	Organisation	Role	Details	Period
Unknown		Indirect Parent	Bulgarian Energy Holding holds the capital of NEK, the company owning and operating Chaira.	Current / not dated
Unknown		Owner Operator	NEK owns and operates Chaira within its Belmeken–Sestrimo–Chaira hydropower cascade.	Current / not dated

Organisations

12 records

Organisations recorded as working on this asset or its project, and their role.

Organisation	Role	Details
	Unit 3 rehabilitation consortiumOperations Maintenance	NEK’s January 2025 announcement names the Voith–ABB consortium for repair and rehabilitation of Unit 3.
	Owner of the operating companyDevelopment And Sponsor Context	Holds the capital of NEK, the owner and operator of Chaira.
	Unit 1 repair contract legal adviceLegal And Finance	Advised Toshiba International on the repair and rehabilitation agreement for Chaira Unit 1.
	Historical second-stage civil worksEpc Balance Of Plant	Carried out civil and tunnelling works during 1996–1999 for the second stage of Chaira, including the pressure derivation and dam-related works.
	Historical construction managementEngineering Consulting And Project Management	The February 1998 project reference documents Harza’s consulting and construction management services for Chaira’s second-stage completion works.
National Electricity Company EAD	Operator	Not set
	Power station owner and operatorOwner Operator	Owns and operates the station and manages its phased restoration.
	Original pump turbine and generator supplierEquipment Supply	Supplied the four original pump turbines and generators for Chaira; Toshiba’s April 2026 account also describes its participation in the restoration programme.
	Restoration cooperation frameworkOperations Maintenance	Signed the April 2026 memorandum with NEK to explore technical support, restoration and sustainable operation of Chaira. The memorandum provides a non-binding cooperation framework.
	Unit 1 repair agreementEpc Balance Of Plant	Toshiba International was advised on the Unit 1 repair and rehabilitation agreement with NEK concluded in January 2025.
	Unit 3 rehabilitation consortiumOperations Maintenance	NEK’s January 2025 announcement names the Voith–ABB consortium for repair and rehabilitation of Unit 3.
	Historical completion financingFinance Insurance Legal	The second-stage completion works were financed through an International Bank for Reconstruction and Development loan, as documented in the February 1998 project reference.

Supplier registration

Developer supplier portal

How suppliers get onto this project's radar: its standing register, supplier portal or contact route.

Suppliers can follow the operator’s buyer profile on the national electronic procurement platform. Participation in published procedures follows the platform’s registration and electronic-signature requirements.

NEK-wide procurement through CAIS EPP; this is a portfolio buyer profile rather than a Chaira-specific standing supplier register.

Supply chain pageContact pageOperator portalwe could not open this

SourceChecked 28 Oct 2026

Capacity history

Recorded project capacity figures. Future-dated changes are shown but are not used as current capacity.

Effective	Capacity type	Capacity	Source
8 Apr 2026	Declared capacity	420 MW	NEK — restored generating capacity reported on 8 April 2026, two units
Current	Technical capacity	788 MW	Bulgarian Energy Holding — installed power in pumping mode

Wind [m/s]

Wave [m]