Photovoltaic (PV) power production ramp-rate control is getting more and more important in weak electric power systems, in which quick and significant power fluctuations can affect the stability of the system. This can be achieved by means of the integration of batteries into large PV plants but such an operation involves an aggressive environment for the ageing of the batteries. This paper presents an evaluation of this ageing by means of the annual simulations of a large PV power plant using actual irradiance data. This is done for different battery sizes used under various degrees of limitation in the power ramp-rate variation. The levelized cost of storage is calculated for each of the cases considered.