The upper reservoir has a maximum capacity of 380,000m3 and is located in a natural crater known as "La Caldera". This reservoir, located at an elevation of 700 m above sea level, is connected to the lower reservoir by means of forced conduits.

The water in this reservoir accumulates as a potential energy as if it were a battery. In periods of wind shortage, the energy is generated from the hydraulic jump produced by the fall of the water from the upper reservoir to the Hydroelectric Power Plant.

The wind farm has 5 wind turbines of 2.3 MW each and a total power of 11.5 MW. With the presence of adequate wind, the wind farm is able to supply the electricity demand of El Hierro. The excess energy that is not directly used by the population is used to pump water from the lower reservoir to the upper reservoir.

The combination of wind and hydroelectric power makes it possible to convert an intermittent and fluctuating source, wind power, into a constant supply of electricity.

The forced pipelines are composed of two 3 km long pipelines that connect the upper and lower reservoirs from an elevation of 700 and 50 meters above sea level, respectively.

The impulsion pipeline, 0.8 m in diameter, is 3,015 m long, and the turbination pipeline, 1 m in diameter, is 2,350 m long.

The pumping station consists of 6 fixed pumping units of 500 kW and 2 variable pumping units of 1,500 kW, with a total power of 6 MW.

The pumping operation is carried out only with wind energy.

Located in a natural watercourse enclosed by a purpose-built earth and rockfill dam, the lower reservoir has a useful capacity of 150,000m3 and is located 50m above sea level.

The water coming from the upper reservoir reaches the Hydroelectric Power Plant formed by 4 groups of turbines of 2.8 KW of power each one, with a total power of 11.32 MW.

The maximum flow in generation is 2.0 m3/s, with a gross head of 655 m.