This article shows how to apply the Grey Clustering with Entropy Weight methodology for the calculation of a unified index of quality in distributed electricity, for which it is necessary to take measurements of electrical service quality parameters such as: the harmonic distortion rate in voltage and electric current, the Sag voltage, the deviation of the electrical frequency, the flickers and the power factor in the most important buses that are: Wind bus, PV/FC bus, Load bus, Grid bus. Finally, the measurements are grouped according to the use and non-use of compensation devices in the simulated power grid. This information becomes the input data for Grey Clustering with Entropy Weight, which allows for the calculation of the scores for each quality parameter. The valuations and measurements will allow for the calculation of the unified electric service quality index. Additionally, this research allows comparison with others that use the methodology of the hierarchical analytical process and for the same purpose and case study. Finally, the research allows the decision to be made on which distributed generation system option will be the most appropriate.