  We discuss a limitation on extracting bounds on the scattering cross section
of dark matter with nucleons, using neutrinos from the Sun. If the dark matter
particle is sufficiently light (less than about 4 GeV), the effect of
evaporation is not negligible and the capture process goes in equilibrium with
the evaporation. In this regime, the flux of solar neutrinos of dark matter
origin becomes independent of the scattering cross section and therefore no
constraint can be placed on it. We find the minimum values of dark matter
masses for which the scattering cross section on nucleons can be probed using
neutrinos from the Sun. We also provide simple and accurate fitting functions
for all the relevant processes of GeV-scale dark matter in the Sun.
