Control Systems Analysis of a 3-Axis Photovoltatic Solar Tracker for Water Pumping

Abstract

We propose 3-axis solar tracker water pumping system. The solar tracker can rotate and tilt using stepper/DC motors and can rise and lower on a tripod using a linear actuator. The charge generated from solar energy absorbed by photovoltaic (PV) cells in the solar panel is stored in a 12V battery that in turn powers two water diaphragm pumps using a solar charge controller. The PV uses four light photocell resistors/sensors to measure light intensity. A solar tracking algorithm determines the optimal angle for PV positioning. Using an ultrasonic sensor to measure the water level in a reservoir water tank, water is pumped from one water tank to the reservoir. Based on soil moisture sensor levels, a second water pump supplies water from the reservoir to the plant. The system is analyzed from a control systems perspective. The transfer functions, root loci, and Bode plots are generated and simulated and experimental results are provided as well as stability and steady-state error analysis.