Currently, evolution of energy sector is being characterized by liberalization, increase of energy needs and technological advances. This evolution has eliminated the scale economy on which the generation, transmission and distribution systems are based. So, tendency of generation systems is oriented to integrated devices, which will supply the customers demand, either in medium voltage or low voltage networks. The interconnection of small modular generation sources to the low voltage distribution network establishes a new concept, the electrical micro-grid. These micro-grids can be connected to the electrical distribution network or work in an autonomous way and can include different technologies, such as: micro-turbines, wind mills, fuel cells, photovoltaic cells, etc., together with energy storage devices, such as: batteries, condensers, fly-wheels, etc. The content of this paper cover different aspects related with generation and distribution of electrical power in a small scale, and horizontal technologies for industrial, commercial and domestic energy systems. So, this paper presents a revision of current developed technologies, which can be used for electrical microgeneration installations.