The Chapter reviews recent advances in computational modeling of photocatalytic solar cells based on semiconductor materials functionalized with earth-abundant transition metal complexes. The studies are focused on fundamental aspects and mechanisms that affect the overall efficiency of photoconversion{,} as determined by solar light absorption{,} charge transport in nanoporous materials and redox properties of molecular adsorbates. The emerging computational approaches include methods for modeling current-voltage characteristics of complete solar cell assemblies{,} conductance of sintered semiconductor thin-films{,} first principle calculations of redox potentials and photoabsorption spectra of molecular adsorbates{,} and inverse molecular design of photocatalytic solar cell components. When combined with structural and mechanistic characterization based on electrochemistry and high-resolution spectroscopy{,} these computational methods are shown to be valuable tools for the design and characterization of new photocatalytic materials. Therefore{,} we anticipate these methods will continue to provide fundamental insights essential for the development of solar cells and materials for the sustainable production of chemical fuels from renewable resources.