Abstract: A method for designing an energy system is provided. An abstract structure of the energy system is determined based on a pre-defined abstract model for each one of the plurality of components. Configuration(s) of a system sizing associated with the energy system are determined. Each of the configuration(s) of the system sizing is determined based on the abstract structure and a set of requirements associated with the abstract structure of the energy system. For each of the configuration(s) of the system sizing, a respective complex structure of the energy system is determined based on a pre-defined complex model for each of the components and the abstract structure, and a performance of the respective complex structure of the energy system is determined based on a set of requirements associated with the energy system. The energy system is designed based on respective performances determined for the configuration(s) of the system sizing.