Solar energy is increasingly being used as a renewable energy source to power various devices. Typical examples are water pumps in heating systems or in agriculture powered by PV panels. However, even on sunny days, clouds can appear temporarily which can significantly reduce the power generated by PV panel. Hence, it might be efficient to additionally use for example batteries or supercapacitors which can contribute to the power supply of water pumps when PV panels are shaded by clouds for short periods of time. This allows the pump to operate continuously without the need to choose powerful and massive PV panels that can provide the required power even in cloudy weather. In this work, a model for the operation of water pump power supply with PV panel and supercapacitor circuit was developed with separate and independent mode control diagrams for PV panel, supercapacitor circuit and water pump. The simulation results confirm their correctness.