We have developed a method based on Time-Dependent Density Functional Theory (TD-DFT) to calculate excitations in solids due to light absorption. This methodology is built on top of the SIESTA method for doing ab-initio DFT calculations with a localized orbital basis. It is capable of handling system containing of order 1,000 atoms and evolving the time-dependent Schroedinger equations for coupled electron-ion dynamics, for time scales of several hundred femtoseconds. This method allows us to study interesting phenomena related to light excitations, by revealing the mechanisms of charge carrier dynamics to elucidate the structural and chemical features that strongly affect such processes.