This paper details the energy efficiency evaluation of an Extendable-Level Inverter (ELI). ELI achieves very high voltage levels, excellent DC-link utilization, and very good power quality with a minimized component count. An experimental setup of a three-phase ELI is implemented to investigate the power losses and to calculate efficiency. The ELI obtained a high efficiency of 99.09% with reduced switching and conduction power losses of 0.1% and 0.81% respectively. Comparative analysis of the theoretical calculation, simulation results and hardware results validated the consistency of a very high efficiency of over 99.09% for a broad range of operating frequencies. The power quality metrics conformed to the limits prescribed in the IEEE 519 standard.