We recently liberated the solid effect of dynamic nuclear polarization (DNP) from its perturbative treatment by describing the relevant spin dynamics in a time domain. This allows us to easily account for dynamical processes that modulate the spin interactions in liquids, like the translational diffusion of spins. Here we additionally model the slow rotational diffusion of the polarizing agent and analyze DNP data from nitroxide spin labels in lipid bilayers at 9.4 T.