The objective of this paper is to make a minutely comparison between 3 different DC microgrids by addressing their most outstanding advantages and disadvantages not only in technical terms, but also regarding other performance related aspects, such as a) measurement of the quality of the electrical supply of the facilities, b) reliability, and c) economic and environmental impact. Results show that in the best case, for all the microgrids, the accuracy of the measurements is around 99.45%, with a weighted average of voltage applied to the load of 24.54 V. The building studied was reimagined into an autonomous and self-sustaining installation by using renewable electric power in direct current with a power distribution on 24 V. Additionally, the systems developed show a potential of greenhouse gas recovery close to 35.05 tCO₂ per year, with a return of investment of 7 years for the renewable-based microgrid and 3 years return for the traditional microgrid. The novelty of this paper relies on the performance comparison of 3 different types of direct current microgrids, one grid-powered (A) based on traditional fuel generation, and two off-grid (B & C) based on photovoltaic energy generation, when feeding a building of considerable size and low operational flexibility.