1. Introduction
(1) Purpose
A conventional solar panel typically converts only 30 to 40 percent of incident solar irradiation into electrical energy. To ensure a consistent output, an automated system capable of continuously adjusting the solar panel’s orientation is necessary. Addressing this need, the Sun Tracking System (STS) was developed as a prototype solution. This system operates autonomously, continuously orienting the panel to face the sun as long as it is visible. What sets this system apart is its reliance on the sun as the primary reference point rather than the Earth. Its active sensors continually monitor sunlight intensity and adjust the panel’s position to maximize exposure.
Given the escalating concerns surrounding energy crises and the effects of global warming, there is a pressing need for solutions utilizing renewable energy resources. Solar energy emerges as a primary contender, offering a clean, abundant, and inexhaustible energy source that mitigates environmental pollution. Photovoltaic (PV) conversion represents one of the most immediate and technologically attractive applications of solar energy. PV cells, functioning akin to classical p-n junction diodes, directly convert sunlight into direct current (DC) electricity through the photovoltaic effect. PV panels, comprising interconnected PV cells, are packaged assemblies designed to maximize power output by maintaining an optimal perpendicular position to solar radiation throughout the day. Achieving this optimal orientation necessitates the integration of a Sun tracker. Compared to fixed panels, mobile PV panels driven by a Sun tracker consistently enhance energy capture efficiency.
(2) Scope
• Suitable for small and medium-scale power generation applications.
• Ideal for power generation in remote areas lacking access to power lines.
• Applicable for both domestic and industrial power backup systems.
• Solar radiation tracking technology has significantly boosted the efficiency of solar panels in recent times, marking a noteworthy technological advancement. The dual-axis solar tracker holds particular significance due to its superior efficiency and sustainability, outperforming fixed solar panels and single-axis trackers. The tracking system is engineered to capture solar energy from all available directions, maximizing energy yield.
(3) Definition
A solar tracker is an automated system designed to orient solar panels for optimal sunlight exposure throughout the day. Its main purpose is to maximize solar energy collection by accurately following the sun’s path as it moves across the sky during different seasons. Dual-axis trackers, with two rotational axes, typically align both east-west (zenithal) and north-south to precisely track the sun’s movement.
Solar tracking technology significantly enhances the electricity production of photovoltaic (PV) systems. Various approaches have been explored to achieve high tracking accuracy. Open-loop tracking relies on mathematical models or algorithms to calculate the azimuth and elevation angles of the sun based on date, time, and geographical location. Closed-loop tracking utilizes sensors such as charge-coupled devices (CCDs) or light-dependent resistors (LDRs) to continuously sense the sun’s position and adjust the panels accordingly.
This paper proposes an empirical research approach to solar tracking, examining both single-axis and dual-axis tracking systems. While single-axis trackers follow the sun’s east-west movement, dual-axis trackers also adjust for the sun’s elevation angle, offering higher accuracy. Most existing research on dual-axis tracking employs two stepper motors or two DC motors, leading to complex tracking strategies and control platforms.
In contrast, this study presents a novel approach using a dual-axis tracker with a single tracking motor, simplifying the control scheme. Both axes of the tracker can move simultaneously within their respective ranges without the need for complex programming or computer interfaces. Conventional electronic circuits are utilized, and a standalone PV inverter drives the motor and provides power, making the system self-contained and autonomous.
Experimental results validate the feasibility and advantages of this simplified tracking system, demonstrating its potential for efficient solar energy collection.
2. Overall Description
(i) Product Perspective
- System Interface
The ATmega328p Microcontroller, manufactured by Microchip, is a high-performance 8-bit AVR RISC-based microcontroller known for its versatility and capabilities. It features 32KB of ISP flash memory with read-while-write functionality, allowing for efficient programming and data storage. Additionally, it includes 1024B of EEPROM for non-volatile data storage, 2KB of SRAM for temporary data storage, and 23 general-purpose I/O lines for interfacing with external devices.
This microcontroller also boasts 32 general-purpose working registers, three flexible timer/counters with compare modes, and support for internal and external interrupts, enabling precise timing and event handling. It features a serial programmable USART for communication with other devices, as well as a byte-oriented 2-wire serial interface and SPI serial port for additional communication protocols.
Furthermore, the ATmega328p integrates a 6-channel 10-bit analog-to-digital converter (expandable to 8 channels in certain package options), allowing for analog sensor data acquisition. It includes a programmable watchdog timer with an internal oscillator for system reliability and offers five software-selectable power saving modes to optimize energy efficiency.
Operating within a wide voltage range of 1.8 to 5.5 volts, the ATmega328p Microcontroller provides a versatile and powerful solution for a variety of embedded system applications.
2. User Interface
It serves as the link between different systems within the system itself or between individual components or units of the system.
3. Hardware Interface
Solar Panel:-
A solar panel, designed to harness the sun’s energy for electricity generation or heating, utilizes photovoltaic modules to convert light energy from the sun into electricity via the photovoltaic effect. These modules predominantly employ crystalline silicon cells or thin-film cells. The structural element of a module can be either the front or back layer, serving as the load-bearing component. Protection from mechanical damage and moisture is essential for the cells’ longevity.
While most modules are rigid, semi-flexible ones exist, typically based on thin-film cells. Electrically, the cells are interconnected in series to achieve the desired output voltage or in parallel to enhance current capability. External connections often utilize MC4 connectors, ensuring weatherproof connections with the rest of the system.
Series connections enable the attainment of desired output voltage, while parallel connections enhance current capacity. Conducting wires carrying current from the modules may incorporate silver, copper, or other non-magnetic conductive metals. Bypass diodes, either integrated within the module or externally applied, mitigate performance loss due to partial shading, thereby optimizing output from illuminated module sections.
Arduino UNO Microcontroller :-
Arduino is a collaborative platform encompassing both hardware and software components, aimed at facilitating the creation of interactive objects and digital devices that can detect and manipulate physical surroundings. It operates under an open-source model, allowing for the free distribution of its hardware and software products under licenses such as the GNU Lesser General Public License (LGPL) or the GNU General Public License (GPL). This enables individuals and entities to manufacture Arduino boards and distribute software without restrictions.
Arduino boards are available in preassembled form or as customizable do-it-yourself kits. They utilize various microprocessors and controllers and are equipped with sets of digital and analog input/output (I/O) pins that can interface with expansion boards (shields) and other circuits. Additionally, the boards feature serial communication interfaces, including Universal Serial Bus (USB) on select models, facilitating program loading from personal computers.
Programming of Arduino microcontrollers is typically done using a subset of features from languages like C and C++. The Arduino project offers an integrated development environment (IDE) based on the Processing language project, in addition to support for traditional compiler toolchains.
One of the commonly used Arduino boards is the Arduino/Genuino Uno, which is based on the ATmega328P microcontroller. It boasts 14 digital input/output pins (with 6 capable of PWM output), 6 analog inputs, a 16 MHz quartz crystal, USB connectivity, a power jack, an ICSP header, and a reset button. The Uno contains all necessary components to support the microcontroller, making it easy to get started by connecting it to a computer via USB or powering it with an AC-to-DC adapter or battery. Its user-friendly design encourages experimentation, with the ability to replace the microcontroller chip at minimal cost in case of errors during tinkering.
LDRs :-
A Light Dependent Resistor (LDR), also known as a photoresistor, is a device whose resistance changes in response to incident electromagnetic radiation, making it sensitive to light. It is alternatively referred to as a photoconductor, photoconductive cell, or photocell, and is typically fabricated from semiconductor materials with high resistance properties.
The photoresistor consists of a semiconductor with high resistance characteristics. In darkness, its resistance can be as high as several megohms (MΩ), while in the presence of light, its resistance can drop to just a few hundred ohms. When light strikes the photoresistor at a certain frequency, photons absorbed by the semiconductor impart sufficient energy to bound electrons, allowing them to move into the conduction band. This results in the generation of free electrons (and their corresponding holes), which conduct electricity and consequently reduce resistance.
The resistance range and sensitivity of a photoresistor can vary significantly between different devices. Additionally, individual photoresistors may exhibit diverse responses to photons within specific wavelength ranges.
Servo Motors:-
A servomotor represents a versatile rotary or linear actuator capable of precise control over angular or linear position, velocity, and acceleration. It comprises a suitable motor linked to a position feedback sensor, along with a sophisticated controller, often in the form of a dedicated module tailored for servomotor operation.
While servomotors do not constitute a distinct motor category, the term “servomotor” commonly denotes a motor suitable for integration into closed-loop control systems.
Functioning as a closed-loop servomechanism, a servomotor utilizes position feedback to govern its motion and final position. Its control input comprises a signal, analog or digital, representing the commanded position for the output shaft.
Paired with an encoder, the motor provides position and speed feedback. In a basic setup, only the position is monitored. The discrepancy between the measured and commanded positions generates an error signal, prompting the motor to rotate in the required direction until alignment is achieved. As convergence nears, the error signal diminishes, leading to motor cessation.
Simple servomotors employ position-only sensing via a potentiometer and “bang-bang” motor control, wherein the motor operates at full speed or halts. Although primarily utilized in radio-controlled models due to their simplicity and affordability, this type of servomotor finds limited industrial motion control applications.
Advanced servomotors employ optical rotary encoders for speed measurement and a variable-speed drive for motor control. Incorporating these enhancements, often coupled with a PID control algorithm, enables quicker and more precise attainment of the commanded position with minimal overshooting.
4. Software Interface Arduino IDE:-
Arduino programming can be done in any programming language that can be compiled into binary machine code for the target processor. Atmel offers their own development environments, such as AVR Studio and the newer Atmel Studio, tailored for their microcontrollers. On the other hand, the Arduino project provides its own integrated development environment (IDE) called the Arduino IDE. This IDE is a cross-platform application developed in Java, originally stemming from the IDEs used for Processing and Wiring languages.
The Arduino IDE features a comprehensive code editor with functionalities like text manipulation (cutting, pasting), search and replace, automatic indentation, brace matching, and syntax highlighting. It simplifies the compilation and uploading of programs to Arduino boards through convenient one-click mechanisms. Additionally, it includes a message area, a text console, a toolbar with common function buttons, and a structured hierarchy of operation menus.
Programs written using the Arduino IDE are termed “sketches” and are saved as text files with the extension “.ino” on the development computer. Previously, versions prior to 1.0 of the Arduino Software (IDE) saved sketches with the “.pde” extension.
The Arduino IDE supports the C and C++ languages, utilizing specific rules for code structuring. It also incorporates a software library from the Wiring project, offering numerous common input and output procedures. User-written code typically consists of two fundamental functions: one for initiating the sketch and another for the main program loop. These functions are then compiled and linked with a program stub “main()” into an executable cyclic executive program using the GNU toolchain, which is part of the IDE distribution. Finally, the Arduino IDE employs “avrdude” to convert the executable code into a hexadecimal-encoded text file, which is then loaded into the Arduino board by a loader program embedded within the board’s firmware.
Follow this link for complete project: Design and Implementation of an Arduino-Based Solar Tracking System
