This book is devoted to small hydropower systems of capacity ranging from hundred watts to hundred kilo watts and is named as micro-hydropower systems. Micro-hydropower systems contain a number of devices including turbines, generators, voltage converters/inverters, voltage and frequency regulators etc used for the conversion of hydropower into electricity of standard voltage and frequency. Development and implementation of micro-hydropower systems is possible in many countries that have some hydropower resources. Micro-hydropower systems would be very useful especially in mountain countries, where it is difficult to construct long transmission lines. At the same time it is obvious that socio- economical development of their remote and mountain areas depend on energy supply to the population, agriculture and industry there. The utilization of the hydropower in these regions will definitely elevate living standards of the community, develop the virgin and unused lands, and populate new lands. Utilization of low power hydropower systems will not create environmental pollution except of visual intrusion.