HPP Zrnovci

HPP Zrnovci is a small hydropower plant on the river Zrnovska in the Municipality Zrnovci and is one of the first hydropower plants in Macedonia. It was put into operation in 1950.

The main intake of HPP Zrnovci is situated on the river Zrnovska, 3,4 km downstream of the machine room. Additionally, there is an intake Kukushnica located 3,5 km downstream of the machine room. The main intake has a capacity of 900 l/s and the width and height of the overflow threshold is 8 m and 2,6 m respectively. Kukushnica intake has a capacity of 100 l/s and width and height of the overflow sill of 5 m and 1 m respectively. Both intakes are Tyrolean. Part of the water is directed to the sludge plant and part to the riverbed. After the sludge plant featuring a fine mesh, the water is directed to the inlet tunnel with a length of about 3,5 km to the water chamber. From the water chamber the water goes to the machine room through a steel pipeline with a length of 360 m.

The machine room is located south east of the settlement Zrnovci. It features two Pelton turbines with horizontal axis and a nominal flow of 0.6 m3/s. Both turbines power two synchronous generators with static excitation and total nominal installed capacity of 1,6 MW. The output voltage of the generators is 6,3 kV. From the buses, power is transmitted to the distribution plant located also in the machine room. There are two oil transformers 6.3/35 kV and 35/10 kV from where via 35 kV and 10 kV transmission line it is transmitted to Kochani and Zrnovci respectively.

After completion of work, through the turbine circuit, water is discharged directly into the river Zrnovka. The management and distribution of electricity is performed in the distribution plant located in the machine room.

Average annual electricity production amounts to 4,5 GWh.

Net drop 220 m
Throughput 2x0.6 m3/s
Turbine type Pelton turbine with horizontal axis
Generator type Synchronous generator with static excitation
Installed capacity 1.6 MW
Efficiency coefficient >90%
Average annual output 4.5 GWh

The river and the riverbed of Zrnovska is a treasure of inestimable value for the municipality, with a high percentage of oxygen O2 in the river (14 mg/l) and rich wildlife. It features exceptionally rare population of Diploneis petersenii, or river Zrnovka is the first locality in Macedonia with registered species that is widespread mainly in northern regions of Europe (Iceland, Finland, Norway) and high mountain ranges (Alps and Pyrenees) and is an indicator of a clean environment.

It is important to mention the existence of endemic river trout Salmo macedonicus and river cancer Astacus astacus found in the upper reaches of the river Zrnovka. Macedonian trout is indigenous and endemic species of fish, characteristic of cold mountain streams and rivers with clean, clear water, rich in oxygen. Apart from the above, the waters of the river Zrnovska also has a number of species of fish shown in percentages of species and density of populations of the measuring profile in Zrnovci: Gobio bulgaricus - krkushka (19%), Barbus balcanicus - black barbell (7%), Pachychilon macedonicum - mergur (22%), Squalius vardarensis - maple (7%), Pseudorasbora parva - amur (4%), Sabanejewia balcanica - Balkan peg (1%), Oxynoemacheilus burechi - vretenushka (1%), Alburnoides bipunctatus - vardarka ( 30%) and Barbatula barbatula - vretenushka (9%) that has a "sanitary" function in ecosystems in terms of improvement of the quality of water through the consumption of organic waste as food.


EVN Macedonia Elektrani DOOEL Skopje
Str. Lazar Licenoski 11
Skopje 1000 North Macedonia
Phone +389 (0)2 3205 000