The possibility of improving the performance of a photovoltaic water pumping system by using different PV cells arrangements was investigated. This is performed choosing two PV cells arrangements namely two and three parallel PV cells. In both cases the Performances of the photovoltaic water pumping system are obtained. It is then compared with each other. Experimental results show that when low heads are required the two parallel cells have higher efficiencies than three parallel cells. However, in the latter case, in spite of lower efficiencies more water is pumped during the day. Furthermore, the results show that designing photovoltaic water pumping systems have two criteria, firstly attention to maximum power of each selected head of motor pump and secondly the costumer’s requirements. Considering both factors help the designer to design photovoltaic water pumping systems more economical.