We demonstrate photoconductivity and conductivity in three-dimensional close-packed solids of colloidal CdSe quantum dots. We observe quantum dot size and surface passivation dependent photoconductivity that can be qualitatively understood by considering the energy required in order to overcome the Coulomb energy of the initial electron-hole pair. Our results suggest that surface ligands that promote initial separation of the electron and hole reduce the electric field required for the onset of the photocurrent. The dark conductance is much smaller than the photoconductance. Hysteretic behaviour and extremely long-lived current transients are observed in the dark current that are suggestive of Coulomb-glass behaviour.