  We consider a general class of electrically charged black holes of
Einstein-Maxwell-scalar theory that are holographically dual to conformal field
theories at finite charge density which break translation invariance
explicitly. We examine the linearised perturbations about the solutions that
are associated with the thermoelectric DC conductivity. We show that there is a
decoupled sector at the black hole horizon which must solve generalised Stokes
equations for a charged fluid. By solving these equations we can obtain the DC
conductivity of the dual field theory. For Q-lattices and one-dimensional
lattices we solve the fluid equations to obtain closed form expressions for the
DC conductivity in terms of the solution at the black hole horizon. We also
determine the leading order DC conductivity for lattices that can be expanded
as a perturbative series about translationally invariant solutions.
