A simple-to-use methodology based on the System Engineering recommendations is presented in order to aid architects and engineers to construct, explore and then analyse the solution space of a defined problem. A functional analysis of the available technologies is conducted in order to feed a database used to generate all the architectures that answer the stakeholders’ requirements. Several topological architectures are derived from the external environments study of the product to design. The objective is to give directions to the product architects to avoid missing promising solutions. Our methodology is applied on the preliminary design steps of an autonomous generator.