The European energy policy is based on two major pillars: integration (of infrastructure networks, markets, standards, and policies) and transition, as set out by European climate policies and by the upcoming Green Deal. The governance model for this common EU policy and the shared energy system it supports is mostly based on multilevel governance (MLG) theories, grounded in the principle of subsidiarity. This paper questions the possibility of MLG in the field of energy, in compliance with the European subsidiarity principle. The coexistence of diverse energy models promoting different scales of reference and actors may result in 'scalar clashes': this hybrid model creates a chaotic status quo, disrupting the EU's transition towards renewable energy sources. Building a common European energy policy that combines the dual objectives of transition and integration does not just require upscaling energy systems, but also setting the adequate scale(s) to implement this transition.