[1] Located in the eastern part of the Rila mountain range, the complex receives waters from the drainage basins of the major rivers Maritsa, Struma and Mesta.

[3] The PSHPPs and HPPs are Chaira, Belmeken, Sestrimo and Momina Klisura with a combined installed capacity of 1,599 MW, producing an average of 1,170 GWh annually.

The generated electricity is lower compared to other power stations in the country, due to the diversion of water for the supply of Sofia and its intended usage to balance short-term consumption changes.

The highest section of the cascade includes three gathering derivations covering a total area of 219 km2 that catch waters from the drainage basins of the Maritsa (45%), the Mesta (32%) and the Struma (23%).

[6] The system of derivations feeds the Belmeken Reservoir situated at an altitude of 1,923 m on the upper course of Kriva reka, a right tributary of the Maritsa.

The geodetic drop to the lower leveler, the Chaira Reservoir, is 689 m. The machine and transformer rooms are located 350 m underground in specially constructed caverns.

[10] The waters from the second level derivations flow to the small reservoir of Stankovi Baraki, constructed in 1965–1974 at the narrowest point of the Kriva reka valley.

Its has a stone dam and a total volume of 0.42 million m3 Stankovi Baraki is linked with the Chaira Reservoir, following the construction of the later, via a derivation.

It has two Francis turbines with a total installed capacity of 120 MW, generating an average of 136 GWh annually and using water discharge of 56.6million m3/s.