Design, implementation and performance of a controller for uninterruptible solar hot water system

This paper describes a novel design and implementation of an automatic control system for solar hot water system in both domestic and industrial purpose. The project consists of one 150 liters evacuated tube solar collector, 300 liter storage tank, solenoid valves and an electric water heater. The objective was to implement an embedded system to control how and from which source (collector or electric heater) the hot water is been provided to the user end. The whole system is solely controlled by the controller which decides how the water should flow to the user end. The controller mainly consists of ATmega32 for central processing, LCD for displaying the level of water inside the tanks, segment displays for showing the temperature inside the tank, a regulator for setting the outlet temperature and a button for confirming the set temperature. The controller is powered by a DC power unit.