Abstract
Solar systems have a very low efficiency. This is because the panels produce their rated capacity wattage only at peak solar noon. This project aims at demonstrating a new system design to increase the efficiency of a solar system using an auxiliary reflector system. Through the project, we elucidate the idea for the design of the system. The project contains the technical description of the idea, its components, the design sketch, and the algorithm used by the micro-controller to automate the entire setup.
Main Idea with Introduction
Global warming and the drive to minimize greenhouse gas emissions have put the focus on how to make the most of natural energy sources. The sun is freely available almost everywhere in the world and electric actuators can help improve the exploitation and efficiency of this sustainable energy source.
Solar tracking is an obvious way to improve the efficiency of solar power plants. As the sun moves across the sky an electric actuator system makes sure that the solar panels automatically follow and maintain the optimum angle in order to increase the direct beam radiation over the panel. This however, has the downside of being irrationally expensive. Solar panels are large and heavy, so to rotate the panels along even a single axis requires a very large capacity motor. Instead of rotating the panel, a reflector, of very low weight, can be rotated. The auxiliary reflector system consists of a guide way to allow the reflector’s movement from the east to the west, and vice-versa. This is accomplished with the help of a linear actuator stepper motor.
The technical description of the working of the system is as follows:
The solar panel is a tilted module, at an angle beta (the Greek alphabet), facing the south in the north-south axis and is mounted on a structure. There is a provision on the mounting structure for the rotation of the panel about the east-west axis. There exist ‘c channel’ guideways to the north and south of the solar panel for the movement of the reflector from east to west, and vice versa. The reflector is oriented along north-south axis to the west of the panel to face the east till noon, and then it is moved towards east and rotated to face the west. The reflector can rotate about the east west axis via manual operation. Additionally it can rotate along the north-south axis via a stepper motor (allows for precise rotation in clockwise and anticlockwise directions). A linear actuator motor is used to move the reflector setup back and forth along the guideway.
In the mornings the auxiliary reflector is positioned to the west of the solar panel; it is moved along the guideway via the linear actuator motor to the east of the panel during solar noon. In the evenings, after sunset the reflector is brought back to the west of the panel, from the east via the linear actuator motor. The reflector is held at the very top of and between two vertical poles. The reflector is tilted at an angle beta (the Greek alphabet) along its axis of rotation with respect to the ground. The movement of the reflector setup is done by attaching a screwed shaft, attached to the bottom of one of the vertical poles using a bolt. The movement of the shaft causes the whole setup of the reflector to move back and forth.
The reflector can rotate along its tilted axis of rotation to face the east-west direction, with the help of an electromagnetic braking stepper motor. The electromagnetic braking is required to provide a passive holding torque to hold the reflector in place, against the force of gravity, without the motor consuming power.
The entire operation is controlled through the use of an Arduino Uno R3 micro-controller board. The linear actuator stepper motor and the electromagnetic braking stepper motor receive power through motor shields.
Arduino Uno R3: Programmed to control and automate the auxiliary reflector system that was built for project S. The program calculates the trajectory of sun rays and controls the position of the reflector to reflect this light onto a nearby solar panel to increase the energy density falling on the solar panel allowing it to produce its rated wattage throughout the day. The program carries out calculations based on the time of the day, date, latitude longitude, position and orientation of the solar panel and the reflector to control the operation of the bidirectional rotation of the electromagnetic braking stepper motor that held the reflector at an angle with respect to the ground; the operation of the bidirectional linear actuator stepper motor to move the reflector setup from the west of the solar panel to the east and vice versa; a wind speed threshold switch that when activated signals the microcontroller to bring the reflector back to a horizontal position so that the reflector is not damaged by the wind; limit switch detection for linear movement; power supply to motors through motor shields; and setting the initial state of the reflector when power on.