  In this paper we make a detailed study of the role of coherent tunneling, on
the photocurrent and power delivered by a quantum dot molecule (QDM) in the
presence of solar light. We focus our analysis on the coherence driven by
tunneling and its impact on the photovoltaic properties of the QDM. The
coherence developed by the system raises as a resource from the interplay
between the strength of the tunneling coupling, the QDM band alignment, and the
coupling rates with the reservoirs of thermal phonons. Our results show that a
QDM can deliver up to 30% more power than a single quantum dot, and our
calculations of efficiency show coherence effects, which are consistent with
the Second Law of Thermodynamics.
