RONA VIA G. PISAN
RICHIE BOY D. RESTAURO
ABSTRACT
Renewable energy solutions are becoming increasingly popular since fossil fuel is a relatively short-termed energy source. One of the most popular renewable energy sources is solar energy. At the educational level, it is therefore critical for engineering and technology students to have an understanding and appreciation of the technologies associated with this area. Presented in this project is a prototype of a solar tracking device using Light Dependent Resistor (LDR). To make solar energy more viable, the efficiency of solar array systems must be maximized. A feasible approach to maximize the efficiency of solar array systems is solar tracking. Solar tracking allows more energy to be produced because the solar panel is able to maintain a perpendicular profile to the sun’s rays. This project covers the design and construction of the solar tracker mechanical structure together with the associated electronic circuits. The technical background and theories essential to the system will also be discussed. One pair of LDRs was installed for detecting the light source position. The solar tracking system is controlled by a pair of operational amplifiers (Op-Amp) that compares the input signals from the LDRs. A DC (Direct Current) motor is mounted to control the elevation angle. A working system will ultimately be demonstrated to validate the design. Possible improvements will be presented.
INTRODUCTION
From the previous year, the Innovators’ Club of Cor Jesu College had developed a project on renewable energy. A solar charger was assembled and made accessible to the school. Although it provided useful source of energy to its patrons, it further needs to be improved. This study was conducted in order to develop and to enhance the aforementioned project. In renewable generation, solar energy is the most popular and has been harnessed by humans since ancient times, using range of evolving technologies. Photovoltaic (PV) systems are, but one example. Solar panels are usually set up to be in full direct sunshine, at the middle of the day, in order to obtain solar energy as much as possible. During the day the sun appears to move across the sky from left to right and up and down above the horizon from sunrise to noon to sunset. Therefore, morning sunlight hits the panels at an acute angle reducing the total amount of electricity which can be generated each day. It takes a whole lot of cells to generate any significant amount of electricity (Layton, 2008).
This setup is inherently expensive because, first, semiconductors which are the main component of PV cells are costly; second, it's not terribly efficient. Some of the sun's energy is lost to heat, and a lot of it doesn't hit the solar cells because the sun isn't stationary. Researches had been conducted to develop methods of increasing the efficiency of PV systems.
One method was the installation of a solar tracker. 2 A solar tracker is a device, where solar panels are fitted, which traces the sun across the sky, throwing more light onto the solar cells. This is far more cost effective solution than purchasing additional solar panels. Solar tracking generate more energy because the solar panel is always maintained at a perpendicular profile to the sun’s rays. Saxena and Dutta (as cited in Lane, 2008) estimated that the yield from solar panels can be increased by 30 to 60 percent by utilizing a tracking system instead of a stationary array.
The solar charger project of the Innovator’s Club has gained number of patrons and need to improve its charging capacity is identified. Bro. Rogelio Enico of the Brothers of the Sacred Heart expressed his interest in this project and offered his help in advertising it. Statement of the Problem In general, there are three methods to increase the efficiency of PV systems. The first method is tracking the path of the sun using fixed control algorithms that uses a controller device that determines the position of the sun with reference to the current day, month and year; the second one is dynamic tracking which is similar to the first method, however sensors are used in determining the current position of the sun; and the third approach is focusing the sun’s incident rays at a focal point also known as Concentrating Solar Power (CSP) technologies. However, the first one consists of complex mathematical models that require in depth analysis; the second involves commercial solar trackers which are extremely costly; and the third method has issues on its longevity. In 3 fact, Tim McGee (2008) found that the Luminescent Solar Concentrator (LSC) prototype only lasts about three months. Currently there are number of variations on each of these methods. The research undertaken in this thesis is directed towards the design of a dynamic tracking system. The dynamic tracking system was chosen because it proposed the most accurate method of maintaining maximum power collection possible. Significance of the Study The solar tracking system can be used in any application that currently uses solar energy. It is ideal on hot water systems and other domestic applications where long-term efficiency is preferred.
The device should provide benefits to the following: 1. CJC-BED, CJC College Department, faculty and staff: Through the maximized power output offered by the solar tracker through its solar panel can invite more patrons to plug their mobile phones to the solar charger. 2. Solar panel owners can maximize in investing on their solar panels without spending much money. Description of Research Study The objective of this thesis is to design a solar tracker. An op-amp-controlled solar panel that can actively track the sun and that can maximize the power received by 4 the panel at all times. This is achieved by using sensors to locate the sun's position at any instance and to align the array using the operational amplifiers.
Objectives of the Study
The objective of this study is to design and construct a solar tracking device that is functional, efficient and economical. Specifically this study aims to:
1. Design and construct a single-axis solar tracking device as a moving base for solar panels;
2. Build a solar tracker that actively tracks the sun for maximum solar panel output;
3. Devise a circuit that drives the sensor to locate the sun’s position at any instance, and to align the array using a bridge circuit;
4. Offer a solar tracking device that is economical and practical.
Scope and Limitation of the Study
The scope of this project involves design and hardware implementation. There has been no formal consideration of the affect of heat on the performance of the array. As for the hardware, design and construction of mechanical structures are needed. The scope of this project is to design a control system that track the sun’s path to maximize solar panel output by using operational amplifiers, LDR (Light Dependent Resistor) as light sensor, and DC (Direct Current) motor as output mechanical device.
DESIGN AND METHODOLOGY This chapter comprises of the conceptual design, system architecture and research procedures that are essential in the development of the solar tracking device. Conceptual Design Commercial solar trackers are one of the ways of boosting solar panel power output. Unfortunately, they are expensive to afford. The proponents came up with a modified version of a commercial solar tracker to see if the cost of present commercial market value of a solar tracker can be reduced without significantly undermining its efficiency. Research which involves the summary, collation and/or synthesis of existing research, and exploratory research was conducted in order to be familiar with the concepts involved upon undertaking this project.
System Requirements
1. During daytime, the system must align itself relative to the sun’s current position.
2. This must be done with active control. It should be automatic and simple to operate. The operator interference should be minimal and 16 restricted when it is actually required. The major components of this system are as follows. Input Light Sensors Control Circuit Output mechanical device (DC motor)
Sensor Design To design the sensor circuit, a suitable method in determining the position of the sun was needed. This involves a process of designing and testing to establish a most efficient and accurate method. The sensors are arranged so that the voltage across each sensor is the same when the sensor points at the sun. The shadow block is used so that the change of sun position will immediately be determined by the sensor. When the sun moves to the sensor 1, the shadow made by the block will cover the opposing sensor (sensor 2). Figure 1. Sensor design 17 Due to the fact that the controller reads the voltage output from the sensors, it is necessary to set the operating range of the sensors to an appropriate voltage range. To accomplish this, the output of the sensors must be sent to an amplifier circuit that will deliver the required voltage range to the controller. Tracking Controller 1. Amplifier Circuit When designing a control circuit for the tracking system, it is important to consider the functions it would need to perform. The functions include comparing and amplifying the analog voltages from the sensor circuit in order to drive the DC motor to the appropriate direction. To handle the comparisons, the amplifier must accept two voltage levels simultaneously and continuously. The LM741 Operational Amplifier was found to be the preferred choice for it can perform all required functions. The Op-amp is a linear device that has all the properties required for nearly ideal DC amplification and is therefore used extensively in signal conditioning, filtering or performing mathematical operations such as add, subtract, integration and differentiation (Mitchell, n.d.). It is a two-input, three-terminal device with a bipolar supply voltage necessary for the forward and reverse action of the DC motor. 2. Controlling Motors The amplifier circuit controls the DC motor by connecting its output to the transistor H-bridge circuit prior to the motor. Four transistors work in diagonal 18 pairs to trigger the motor forward or reverse. Refer to the schematic diagram for the motor drive circuit. System Architecture Figure 2 (a) below shows the mechanical design for solar tracking. It consists of the solar panel, sensor and motor. Figure 2 (b) shows the elevations of the solar tracker and its degree inclinations.
System Architecture
Figure 2 (a) below shows the mechanical design for solar tracking. It consists of the solar panel, sensor and motor. Figure 2 (b) shows the elevations of the solar tracker and its degree inclinations.
Block Diagram
This design monitors the position of the sun using two Light Dependent Resistors (LDRs), and directs the movement of the solar panel to correctly orient to the sun. The output configuration is called an H-bridge which drives a small DC motor at the input voltage (5 –12V), both forward and reverse. Figure 3. Block diagram The input stage consists of two LDRs. The op-amps in the control circuit are fed by the junction of these LDRs. The control stage uses two operational amplifiers to decide on the direction of light. If both LDRs see the same amount of light, their resistance is equal. The junction of the LDRs’ would be at input voltage divided by two i.e. 12V input – junction of LDR and LDR’ is at 6V. If the light on one LDR is greater than the other, then the voltage will move, higher or lower depending on which LDR has more light. The voltage output from the control circuit will drive the DC motor forward or reverse directing the position of the solar panel mounted on the tracker. The output of the solar panel can be used for user’s desired purposes and can also be used to power the DC motor
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