Abstract Here we present the technical and economical performances of a small scale trigeneration power plant based on solid oxide fuel cells and designed for a small residential cluster (i.e. 10 apartments). The energy system features a natural gas solid oxide fuel cell, a boiler, a refrigerator, and a thermal storage system. We compare different power plant configurations varying the size of the fuel cell and the refrigeration technology to satisfy the chilling demand (i.e. absorption or mechanical chiller). Given that the ability to meet the power demand is crucial in this kind of applications, the plant performances are assessed following an optimal control strategy, as a function of different energy demand profiles and electricity prices, and of rated and part load efficiencies of each energy converter. The optimization of the energy system operating strategy is performed through a graph theory-based methodology. Results are provided in terms of electrical and thermal efficiency, operating strategy, as well as economic saving, primary energy consumption reduction, and pay back period, considering different capital costs of the fuel cell.