Design & Implementation of a Dual Axis Solar Tracking System

Abstract

Abstract. The aim of this paper is to present a solar energy collection technology by a photovoltaic cell. To present this efficient solar distributed generation system, a dual-axis solar tracker is designed, built and tested. The tracker actively tracks the sun and changes its position accordingly to maximize the power output. The designed tracking system consists of sensors, comparators and microcontroller operated control circuits to drive motors and gearbearing arrangements with supports and mountings. Two geared stepper motors are used to move the solar panel so that sun's beam is able to remain aligned with the solar panel. The built system has a calculated power gain of 52.78% compared to a static solar panel.Keywords: Solar tracker, LDR, Microcontroller, Geared stepper motor, Power gain.1 INTRODUCTIONThe present condition of worldwide crisis for major energy resource causes a huge raise in the prices of combustible sources of energy. So there is a growing demand to find greener ways to power the world and minimize green house gas emission. In this worst challenging condition there is no other way than to find for renewable energy resource [1].The sun is the natural power source that will keep on sharing its energy and most unlikely to vanish. It is a renewable resource that is clean and economical. This energy is available everywhere but due to geographical location Bangladesh receives the maximum amount of energy from sun [2]. Therefore, solar energy is rapidly getting popularity as an important means of expanding renewable energy resources. But most of the solar panels in Bangladesh are positioned on a fixed surface such as roof. As sun is a moving object, this approach is not the best method. One of the solutions is to use a solar tracker that will actively follow the Sun. A solar tracker is a sensory device built with the solar panel which tracks the motion of the sun across the sky and moves the solar panel according to that motion of the sun, ensuring that the maximum amount of sunlight strikes the panels throughout the day. After finding the sunlight, the tracker tries to navigate through the path ensuring the best sunlight is detected. Commercially, single-axis and two axis tracking mechanisms are available. Previous researchers [3] used single axis tracking system which follows only the Sun's east-west movement. But the earth has two types of motion, the daily motion and the annual motion. The daily motion causes the sun to appear in east to west direction over the earth where as the annual motion causes the sun to tilt at an an le o while moving along east-west direction [4]. So the maximum efficiency of the solar panel is not being used by tracking system is necessary. With the sun always facing the panel, the maximum energy can be absorbed as the panel operates at its greatest efficiency. The main objective of this paper is to improve the power gain by accurate tracking of the sun.To develop this dual axis tracking system light dependent resistor (LDR) is used as sensor. The resistance of LDR decreases with increasing light intensity [5]. Two dual Op-amps are used as comparator for comparing the light intensity in two different axes. Again diodes are used for neglecting the negative voltages coming from the comparators. Microcontroller generates the suitable control signals to move the motors in the proper direction. But the microcontroller output ranges from 0 to 5 volt [6]. So to increase the voltage and current level motor driver is used. Two 12 volt full geared stepper motors are used here for rotating the solar panel in two different axes.2 METHODOLOGYIn order to simplify the design process the whole system is divided into four different units. These are: light sensing unit, light comparison unit, control unit and movement adjustment unit. Fig. 1 shows the overall block diagram of the whole system.2.1 Light sensing unitLight sensing unit consists of five sensors. …