The storage of energy is a very important part of a photovoltaic system. Lithium-ion and lead-acid batteries are generally used for this purpose. This article compares the performance of these two types of batteries in a photovoltaic (PV) system under variation of temperature and state of charge. The PV generator, the lead-acid battery or the lithiumion battery were modelled and then simulated using the Matlab / Simulink simulation environment. By taking into account the influence of temperature and state of charge, the simulation results show that lithium-ion technology is the most suitable for the storage of energy in a photovoltaic system.