This paper presents two mathematical motor-pump models for photovoltaic (PV) applications. These models will allow us to obtain the operating point with the PV array and the flow rate of the pumped water. The modelled motor-pump characteristics are current-voltage and flow-voltage. The model, are established for centrifugal and positive displacement pumps coupled to DC motors. The experimental data is obtained in our pumping test facility. A simplified method is proposed to obtain the parameters of these models in order to reduce the number of experimental measurements to the minimum. (c) 2005 Elsevier Ltd. All rights reserved.