The accuracy of our GAPW implementation is compared first, to an all-electron quantum chemistry code and second, to the well-established pseudo potential GPW code with max errors not exceeding 3.40×10 -5 Hartrees/atom for ground-state energies and 0.09 eV/Å for ground-state forces, 0.01 eV for vertical excitation energies and 0.09 eV/Å for forces associ-ated with first singlet or triplet excited states, for both comparisons. Local features such as the V N N B defect in hexagonal boron nitride are accurately reproduced with errors of 0.2 or 0.4 eV in comparison to highly accurate GW-BSE reference computations or experimental data. The presented method developments pave the way for further advancements in the description of localized features and excited core states in solid-state materials, as required e.g. for time-resolved X-ray spectroscopy.