A theory for adiabatic electron transfer between a semiconductor electrode and an electron acceptor species in a polar electrolyte is developed by extending the Anderson-Newns model as adapted for metal/electrolyte interfaces. It is shown that perturbations of the electrode electronic spectrum can lead to qualitative changes in Marcus free energy curves and thus in the electron transfer kinetics. In particular, the adiabatic solvent free energy curve may exhibit a triple well structure even when the linear response model is used to describe the solvent polarization fluctuations.