We study arrays of disordered nanowires arranged in parallel and in contact between two metallic electrodes. If one adjusts with a back gate the chemical potential to one edge of the impurity band, these arrays open promising perspectives for energy harvesting and heat management in a temperature range where the electrons propagate inside the nanowires by phonon assisted hops between localized states. On one hand, the thermopower self-averages to large values while the electrical conductance scales with the number of nanowires. This gives large power factors and suitable figures of merit for the thermoelectric conversion. On the other hand, the phonons are mainly absorbed near one electrode and emitted near the other. This phenomenon can be exploited for cooling hot spots in electronic circuits.