This project has shown that renewable energy sources are more common now then ever before while the main topic is the basic principle of small hydropower plants, where they use the potential energy of water, convert it into kinetic energy, and then into mechanical energy and through generators into electricity. The basic difference between large and small hydropower plants and their biggest advantages and disadvantages are also shown. The properties and main characteristics of SHPPs are also presented. The paper also presents the main division of SHPPs. The second chapter describes the main division of small hydropower plants, where all parts are described separately, where it can be studied how which part of a small hydropower plant works. The difference between the parts of small and large HPPs is also visible. The third chapter presents SHPPs in Croatia and around the world. In Croatia, the usability of SHPPs is low, but the potential is very high, while in the world and Europe, the trend of building small hydropower plants is growing, due to its great advantages. China, Canada and the US are the largest hydropower users in the world, where China has the largest HPP in the world. The last chapter presents the different types of construction and problems of SHPP construction. During construction many impacts should be taken into account such as climate, size of construction, terrain, gross energy potential, etc ..