Development of a motion sensorless solar-powered irrigation pump is a challenging task due to irregular solar insolation and correspondence variation in water flow rate. For an uninterrupted water supply irrespective of climatic conditions a battery-integrated brushless dc motor coupled with solar-powered irrigation pumping system is presented here. Irregular and frequent solar insolation variations cause disturbances in control loop, which causes fluctuation in the motor speed and, finally in the water flow rate. To address mentioned problem, a lower order disturbance rejection (LADR) based position sensorless speed control is implemented here, which fulfills constant water flow requirement for crop-specific irrigation application. Using a state observer along with LADR control, the irregular solar insolation variation is controlled. The use of position sensorless control algorithm makes developed system compatible with both surface mounted as well as for submersible water pumping. Integration of battery-connected bidirectional power flow control enables designed system to run twenty-four hours at full capacity. Integration of the battery in the system enables it to feed local loads. Systematic analysis for stability and disruption rejection at irregular insolation variation of designed system guide parameter tuning of control loop. Experimental results under different testing conditions establish the reliability of developed system.