  The electron kinetics in nanowire-based hot-carrier solar cells is studied,
where both relaxation and extraction are considered concurrently. Our kinetics
is formulated in the many-particle basis of the interacting system. Detailed
comparison with simplified calculations based on product states shows that this
includes the Coulomb interaction both in lowest and higher orders. While
relaxation rates of 1 ps are obtained, if lowest order processes are available,
timescales of tens of ps arise if these are not allowed for particular designs
and initial conditions. Based on these calculations we quantify the second
order effects and discuss the extraction efficiency, which remains low unless
an energy filter by resonant tunnelling is applied.
