In this paper, parallel interconnection of buck (step-down) converters is considered. Classical control of such a topology uniformly distributes load current over branches. Yet, whenever non-identical converters (having distinct characteristics) are considered, this paper demonstrates, both theoretically and experimentally, that minimizing overall losses requires non uniform and even load-depend current distribution. In this context, a novel highly modular hierarchical control framework is proposed for arbitrary number of buck converters. Solutions for the two related design steps are given, which leads to a control law minimizing total losses as well as correcting voltage deviation for any operating point and without knowledge about load magnitude. Several formal statements and experimental results support our discussions.