In the frame of a common project on the development of prototype micro-cogeneration systems for household applications, ENEA and FCLAB have characterized a 1kW_el and a 2.5kW_el tubular-type SOFC technology-based unit respectively. Spanning the entire operational window of the two systems (within boundary conditions set by safe and durable operation, i.e. limitations on fuel utilization, oxygen-to-carbon ratio, stack and exhaust temperature profiles) the performance and efficiency characteristics of the two systems have been fully mapped. Thus, a technical-economical evaluation can take place for a calculated assessment of the optimal allocation of the two scales of systems.