In the current energy transition context, microgrids and multi-energy systems are becoming more and more important in practical applications. The investigation carried out in this paper is based on practical energy planning tasks implemented on different microgrids. The motivation for feasibility evaluation of microgrids for the purposes of ecotourism came from the realistic needs related to numerous resort energy supply related problems. These resorts have specific hourly energy demands in terms of heating, electricity, and transport. The integration of these three sectors is investigated with the aim of achieving a synergistic effect and decreasing total costs (investment and operational). The starting hypotheses for this work refer to the integration of such microgrids with the power market. The physical prerequisite is the construction of a connection line between a microgrid and the existing external power system. The HOMER software tool is used as an analytical tool for simulation, optimization and sensitivity analyses within the scope of the microgrid feasibility study of an eco-tourist resort near Trebinje. The methodology of the widely used HOMER software is extended to the variation of connection line power, having in mind the central hypothesis that it will affect its total costs. The obtained results show that when the connection line is constructed, total costs decrease by 43%; when the connection power line is upgraded, costs decrease by additional 5%. It is also confirmed that electricity prices on the power market have a significant influence on the feasibility of investments within the microgrid generation structure. This article contributes to the feasibility study methodology in the direction of including significant impacts of line rating and market conditions.