HPP Pena is located on the river Pena in Tetovo Municipality, in the northwest of the Republic of Macedonia in Polog Valley.

It is the first hydropower plant in Macedonia, put into operation in 1926. The plant worked until 1979 when it was damaged in the floods of the river Pena. It was reconstructed in the period from 1980 to 1984 when it was again put into operation with an output of 2,5 MW. The last reconstruction was made in 2008 when the plant was fully automated, which increased its installed capacity.

The catchment of HPP Pena is located approximately 12 km downstream from the confluence of the river Pena in the Vardar. The grip is Tyrolean, and the height and width of the overflow threshold is 1.96 m and 20 m respectively. The catchment of HPP Pena receives 5 m3/s and the overflow water amount is 200 m3/s. The flow of water into the intake is regulated by table flaps and a coarse mesh which catches the bulky material of the river. From the intake through the sludge receiver and through the intake tunnel with a length of 1 km water is transported in the water chamber and from the chamber through a steel pipeline with a length of 150 m water is transported to the machine room.

The machine room is located on the left bank of the river and it houses the mechanical room where there are two Francis turbines with horizontal axis. The nominal flow of one turbine is 2 m3/s and of the other 3 m3/s. These two turbines drive synchronous generators with rotating diodes respectively so that one generator has installed capacity of 1,3 MW, and the other 2 MW. The output voltage of these generators is 6,3 kV. Further, via the transformer 6.3/35 kV and 35 kV transmission line electricity is transmitted to Tetovo. Additionally, via the 35/10 kV transformer electricity is transmitted to Shipkovica and Selce villages.

After exploiting the energy potential of water, from the turbines water runs into the drainage channel which discharges it into the river bed.

The average annual electricity generation is 13 GWh.

The area around the location of HPP Pena features several types of forest communities, mostly plantation of oak and beech. Endemic species are represented with some of Balkan distribution and local endemics. In terms of fauna, there are various species of insects, amphibians, reptiles, birds and mammals.

In the upper parts of many mountainous streams there is trout of the family Salmonide, more specifically a kind of stream trout. In the center lower flows there is barbell and chub.