In this paper, we have carried out the electrical performance and the cost-benefit analysis of a domestic microgrid based on renewable energy sources. The software used in this work in order to perform the simulations is Homer Pro, which enabled modelling of microgrid and all its parameters in a period of one year, accounting the real weather conditions and usage hours of the electric loads of the building we are working with. The microgrid consists of polycrystalline photovoltaic panels, a set of batteries, the utility (depending on the case study), and the load, which represents a prototype house and an inverter and controller that allow us to manage the energy flows between all the elements of the microgrid. Two case studies were conducted; in first, our microgrid was isolated from the electrical network and in the other, we counted on its support.