Recent methods for the determination of nominal electric power of photovoltaic (PV) water pumping systems for irrigation have been based on graphic tools of manufacturers and/or proper calculations, whose basic incoming parameters are: hydraulic energy demand, monthly average daily solar irradiation and characteristics of PV water pumping system. However, in this procedure has been separately considered the demand for hydraulic energy and possibilities of its production from the available solar energy with the PV water pumping system. Further, it have not been considered the dynamic characteristics of boreholes as well as the water storage in the soil during the season of irrigation. All of this has resulted in an unsystematic and therefore rather imprecise procedure of the system sizing, whereby it has been often overrated, which consequently reflected the higher investment and eventual economic sustainability of those systems. Through this dissertation was given the scientific procedure of the sizing of the optimal PV water pumping system for irrigation. In this sense, it is systematically analysed the subject problem and completely considered all the relevant system elements and their characteristics, i.e. characteristics of PV water pumping system, water supply from boreholes, local climate, soil, crops and irrigation methods. The objective function is the minimization of the maximal nominal electric power of PV generator (MIN-MAX procedure) and the hybrid simulation-optimization model was applied, wherein for the optimization was used the dynamic programming, while the constraints are defined by the simulation model. For all that, the system is viewed without the water and/or energy accumulation, further the irrigation system by trickle distribution method and for the PV water pumping systems of the second generation submersible motor-pump subsystem. For the purpose of the verification of the model optimization and reaching appropriate researching results, as well as gaining the knowledge of the applying possibilities of PV water pumping systems for irrigation in Croatia, were chosen the locations in Osijek and Split areas. By variation of different parameters was shown that this model successfully takes into consideration all characteristic values and their relations in the integrated system, whereby through this model could be, in satisfactory way, determinated the optimal value of PV water pumping system for irrigation.