To allow social and economic development of arid and isolated areas of Algeria, which represent 87% of the total area, one must provide energy and water. The photovoltaic (PV) pumping systems are expected to offer the appropriate solution for water supply in order to meet drinking and irrigation needs in these remote and scattered regions. In this study, we propose the improvement and validation of two mathematical motor-pump models for PV applications. These mathematical models describe the behavior of the motor pump's sub-system, using the characteristics parameters, current, voltage and pumping rate simulated for different pumping heads in the real conditions of operations. Because the motor pump manufacturer cannot provide the user or the farmer all the data for any application, the difficulties and the generation of failures will be on the field. The built pumping test facility of the Centre for the Development of Renewable Energies (CDER, Algiers, Algeria) avoids all these difficulties, by characterizing the various sub systems motor pumps for the area selected. The models were based principally, on the analysis of the experimentation results for two centrifugal pumps and two positive displacement pumps, coupled to DC motors. The current, the voltage, the flow rate and the head were the monitored dates. Current-voltage and flow-voltage were the modelled characteristics of the modelled motor-pumps. The improved models yielded satisfactory results'. (C) 2017 Elsevier Ltd. All rights reserved.