In this “renewable era”, researchers’ eyes are diverted to the Microgrids (emerging power systems consisting of a number of heterogeneous components including renewable and non-renewable energy sources, storage systems and energy loads) to exploit their functionalities in order to improve today’s power systems. This work addresses two significant issues encountered in the Microgrid (MG) management systems: 1) the semantic interoperability, highlighting the need to ensure a seamless communication between several heterogeneous components, and 2) the multi-objective aspect of the MG, emphasizing the need to model all the aspects involved in the achievement of the MG objectives. Here, we propose OntoMG, a full-fledged Microgrid ontology, to resolve these two issues by providing an interoperable information model with existing standards and by modeling all the aspects/functionalities involved in the achievement of the MG objectives, namely: Identification, Operational, Mobility, Economical and Ecological. This research is undertaken in collaboration with Jema Irizar Group, leader of the ISare Microgrid Project, a real-size MG built in the Basque Country.