A fully consistent model to study electrodynamics for superconductors in the stationary and non-stationary regimes has been developed based on Proca equations and a massive photon. In particular, this approach has been applied to study the electric field penetration depth in superconductors. The model shows a deviation from the charge contribution to an internal electric field compared to previous approaches. (c) 2007 Elsevier B.V. All rights reserved.