The different representations of the input data for energy system studies need to be conducted to the same time step for the purpose of carrying out power system calculations. Availability of data with different time steps, or even provided with irregular timing, needs a pre-processing phase to unify the representation within the same time step. This paper describes a dedicated pre-processing tool that accepts input data with different characteristics and provides a regular representation of the output. A specific application in which the differences between the time steps are relevant is analysed by considering a grid-interfaced system with local generation and local load, carrying out the input/output energy calculations and the assessment of the energy-related economics in net metering conditions.