The ability of quantum simulations to predict the electronic structure at donor/acceptor interfaces and correlate it with the quantum efficiency of organic solar cells remains a major challenge. The need to describe with increased accuracy electron-electron and electron-hole interactions, while better accounting for disorder and environmental screening in realistic interfaces, requires significant progress to improve both the accuracy and computational efficiency of available quantum simulation methods. In the present study, the results of different ab initio techniques are compared, namely time-dependent density functional and many-body perturbation theories, with experimental data on three different polymer/fullerene heterojunctions. It is shown that valuable information concerning the thermodynamic drive for electron-hole dissociation or recombination into triplets can be obtained from such calculations performed on model interfaces. In particular, the ability of these approaches to reproduce the Veldman and co-workers classification of the three studied interfaces is discussed, showing the success and limits of state-of-the-art ab initio techniques.