Hydropower, as well as most other renewable energy sources are caused by solar activity, which promotes evaporation from the seas, oceans and water bodies, subsequent formation of water vapor, clouds, and finally return back to the surface in the form of precipitation, creating a closed water cycle (water cycle). Energy which follows offers us water, can then be used to produce electricity from hydropower. The advantage of these funds is their flexibility and also the fact that the production of electricity produces harmful emissions (including greenhouse gases). With large hydropower and water works, however, have shown their negative impacts on the environment and local ecosystems.
From this perspective, the environmental resources considered acceptable with smaller hydropower installed capacity, ie. small hydropower plants (HPP). Their classification is currently fragmented and so is the MVE in India and China consider power plant of 25 MW, in Latin America with the performance even up to 30 MW, while the European Union set a limit of 10 MW, but the individual Member States have put this figure even below 5 MW, Germany and Italy even only 3 MW. At the same time these sources should meet certain criteria in terms of location should go to a certain degree of decentralized resources, often abandoned or placed into. remote areas, their advantages should be easy adjustability, in most cases should be locally owned and particularly satisfying local demand for energy, priority should be to the individual technical solution and the least impact on the environment.
Slovakia was in small hydropower plants in 2005 produced 250 GWh of electricity. Cumulative installed capacity in 2006 was 63 MW in Slovakia. According to official studies and strategy papers ("A strategy for greater use of renewable energy," respectively. Proposal "Energy Security Strategy of Slovakia until 2030") should be taking into account all the environmental risks produced in small hydro power plants in Slovakia in 2010 and 350 GWh 2015, a total of 450 GWh of electricity.