The task which is tackled with designing future energy systems is to build up a combination of technical facilities which can be used in future to provide the demand of usable energy predominantly from renewable energy sources. One major key to do this successfully is systems knowledge of intercorrelations between technical elements, environment, and society. Against this background in this chapter insights from systems analyses needed for policy support, basic theoretical systems views, derivation of fundamental systems characteristics for resilience, empirical findings from the Ahr-flood disaster, thoughts for a meaningful combination of systems knowledge, and practical requirements for the provision of applicable knowledge for action and for evaluating alternative options are gathered and put together. The results are an in-depth analysis of the field of energy systems analyses for resilience modelling and basic recommendations for building up a stress test tool as a nucleus for further endeavours in this direction.