The first advantage for studying dynamic model structural properties lies in the fact that results are available for every parameter numerical value. Much research has already been carried out on this notion of structural analysis. This article focuses on this approach in a bond graph context and more particularly to conclude about the model's structural invertibility. After having introduced the subject, section II establishes three necessary conditions for a model to fulfill structural invertibility. Section III shows an additional necessary structural condition if one desires to obtain an inverse model of minimal order and, section III presents the notion of the essential order for output specifications. Section IV shows how such a structural invertibility diagnostic can be beneficial for sizing mechatronic systems. Finally section V summarizes the main features of this approach and gives some directions that are worth investigating.