We provide an optimization oriented formalization of correct-by-construction design following the principles of Platform-Based Design.1 The design proceeds by refinement steps. At each step, a specification is given in terms of requirements to be satisfied by an implementation. The implementation choices are implicitly captured by a set of components, their properties, and their composition rules. A class of candidate implementations of the specification is derived by formulating and solving an optimization problem. The implementation becomes the specification for the next step in the design flow. We show how the optimization oriented formalization enables design space exploration, and we present the trade-offs involved in the selection of the refinement steps. We show how the methodology can be applied to the design of electric power systems by decomposing the design flow into the following steps: generator selection, generation of the connection configuration under faults, and topology design of the power distribution system.