Density functional theory (DFT) and time-dependent DFT are useful computational approaches frequently used in the dye-sensitized solar cell (DSSC) community in order to analyze experimental results and to clarify the elementary processes involved in the working principles of these devices. Indeed, despite these significant contributions, these methods can provide insights that go well beyond a purely descriptive aim, especially when suitable computational approaches and methodologies for interpreting and validating the computational outcomes are developed. In the present contribution, the possibility of using recently developed computational approaches to design and interpret the macroscopic behavior of DSSCs is exemplified by the study of the performances of three new TiO2-based DSSCs making use of organic dyes, all belonging to the expanded pyridinium family.