  We examine the excitation transport across quantum networks that are
continuously driven by a constant and incoherent light source. In particular we
investigate the coherence properties of incoherently driven networks by
employing recent tools from entanglement theory that enable a rigorous
interpretation of coherence in the site basis. With these tools at hand we
identify coherent delocalization of excitations over several sites to be a
crucial prerequisite for highly efficient transport across networks driven by
an incoherent source. These results are set into context with the latest
discussion of the occurrence and role of coherence in light-harvesting
complexes that are exposed to natural incoherent sun light.
