since the recent introduction of a marking system to compare the performance of PV inverters one of the most topical
issues in this field. This paper questions the adequacy of the current definition(s) of the European efficiency to reflect
accurately the performance of inverters. It proposes a new quantity to quantify the performance of inverters: the
maximal reachable European efficiency. This new definition of the European efficiency is either based on the
distribution of the annual yield as a function of MPP power and voltage or on the existing weighting factors. The
definition of the maximal reachable efficiency is basically based on the concept of required MPP voltage band. It
therefore considers a realistic operation domain in which an average efficiency can be computed. A comparison
between the current definition of the European efficiency and the proposed quantities is provided, also taking into
account the impact of the location. As a good compromise between simplicity and accuracy, the proposed concept of
maximal reachable European efficiency should be adopted to quantify inverters efficiency.