The storage of energy in batteries is a cause of the failure and loss of reliability in PV systems. The battery behavior has been largely described in the literature by many authors; the selected models are of Monegon and CIEMAT. This paper reviews the two general lead acid battery models and their agreement with experimental data. In Order to validate these models, the behavior of different battery cycling currents has been simulated. Results obtained have been compared to real data. The CIEMAT model presents a good performance compared to Monegon's model. (C) 2008 Elsevier B.V. All rights reserved.