In power electronics-based microgrids, the computational requirements needed to implement an optimized online control strategy can be prohibitive. This paper proposes the derivation of a geometric manifold in the energy-power domain that is based on the a-priori computation of the optimal reactions and trajectories for classes of events in a dc microgrid. The proposed states are the stored energy and power of the dc-dc converter. It is anticipated that calculating a large enough set of dissimilar transient scenarios will also span many scenarios not specifically used to develop the surface. These geometric manifolds will, then, be used as reference surfaces in any type of controller, such as a sliding mode hysteretic controller.