Abstract
For photovoltaic system charge controller plays an important role as the system’s overall success depends mainly on it. This thesis presents design & development of a photovoltaic charge controller with the function to disconnect and reconnect battery and load during battery overcharging or discharging and indicating different battery voltage levels with the help of light emitting diode. Furthermore, this smart charge controller is developed using PIC microcontroller 16F77 to control the home appliances using any infrared remote. The efficient disconnecting/reconnecting action and controlling of home appliances from remote place is accomplished by relay switches. To receive the infrared signal an IR receiver has been interfaced with the microcontroller. To control the intensity of light/fan a MOSFET has been interfaced with the microcontroller. The program for the system has been developed using C programming language and compiled by mikroC compiler for the system. The whole system has been interconnected and the developed program has been burnt into the microcontroller using PicKit2. The performance of the system has been studied and it is found that the system works properly without any interruption. The coverage range of the remote control has been measured and found that it works properly from a distance of 7 m.
Table of Contents
1.3 Motivation of the project. 2
1.4 Future scope of the project. 4
1.5 Organization of the thesis. 4
3.2 Types of charge regulation. 11
3.3 Two stage charge controller. 13
3.4 Charge controller set point. 14
3.6 Basic Structure of microcontroller. 18
3.7 Families of Microcontroller. 19
3.8 Criteria for choosing a microcontroller. 21
3.9 Advantages and Disadvantages of Microcontroller 21
3.10.1 Microcontroller PIC16F77. 21
3.12.1 Remote(RC5 protocol) 30
3.13 7805 Voltage Regulator. 34
4.1.1 Voltage sensing circuit 38
4.1.2 Voltage regulation section. 39
4.1.4 Charge State Indication Section. 41
4.1.6 Brightness control section. 42
4.1.7 Calculation of different battery voltage level 43
List of Figure
Figure 1 Hysteresis loops in charge controller for voltage sensing. 8
Figure 2: Block diagram of microcontroller based charge controller. 9
Figure 4: Shunt Regulation. 12
Figure 5: Series regulation. 13
Figure 6: Two stage series charge controller. 14
Figure 7: Charge Controller set points. 15
Figure 8: Microcontroller PIC16F77. 18
Figure 9: Basic Block Diagram of Microcontroller. 19
Figure 10: PIC16F77 PIN Diagram.. 22
Figure 11: PIC 16F77 clock circuit. 29
Figure 12: RC5 Protocol Logic “1” & Logic “0”. 30
Figure 13: 14-Bit RC5 Signal. 31
Figure 15: IR Sensor (SM0038) 33
Figure 16: SM0038 PIN Diagram.. 34
Figure 18: IC 7805 PIN Diagram.. 35
Figure 20: MOSFET IRF 840 PIN Diagram.. 36
Figure 21: Voltage sensing circuit. 38
Figure 22: Voltage regulator circuit. 39
Figure 23: Circuit symbol for a relay. 40
Figure 24: Implementation of Relay switching.. 40
Figure 25: Charging/Discharging state indication. 41
Figure 26: Block diagram of infrared system.. 42
Figure 27: LED brightness control by PWM… 43
Figure 28: Charge controller Circuit diagram.. 45
Figure 30: Battery charging state with LED indication. 49
Figure 31: Battery discharging state with LED indication. 49
Figure 32: Battery charging and discharging state with indication. 50
Figure 33: DC load control by remote control. 51
Figure 34: DC load control by remote. 51
Figure 35: LED brightness control by remote. 52
Figure 36: LED brightness control by remote. 53
Figure 37: LED brightness control by remote. 54
Figure 38: LED brightness control by remote. 55
Chapter ONE
Introduction
1.1 Background to the study
Charge controller is an essential part in solar photovoltaic system as well as in wind energy system where regulation of power is necessary for maintaining efficient and secure storage system. Current state-of-art design for charge controllers are capable of handling large amount of charge with the assistance of microcontrollers that play a key role in the development of integrated circuit design. Charge controllers operated by microcontrollers take decisions by itself with the help of program burrowed in its flash memory. In this project, our effort is to build a microcontroller based charge controller that will allow us to control our dc home appliances using an infrared remote, that are connected via charge controller to the solar panel rather than the battery . In addition to that, speed regulation of a dc load(Dc light/fan),connected in the same manner, is implemented by using PWM technique. This project work can not only be used for home automation, it can also be implemented to control industrial heavy loads from remote place.
The rising global concern for environmental sustainability and the increasing demand for renewable energy sources have made solar power a critical area of focus. Solar energy, being abundant and renewable, offers a viable solution to the world’s growing energy needs. As the reliance on solar energy intensifies, the necessity for efficient and reliable solar charge controllers becomes paramount. Solar charge controllers are essential components in photovoltaic (PV) systems, ensuring that batteries are charged correctly and protecting them from overcharging and excessive discharge.
In recent years, the advancements in solar charge controller technology have significantly contributed to the efficiency and longevity of solar power systems. These advancements include the integration of Maximum Power Point Tracking (MPPT) technology, pulse-width modulation (PWM), and other sophisticated algorithms that enhance energy harvesting from solar panels. The implementation of these technologies ensures that solar power systems can operate optimally, providing a steady and reliable power supply, especially in off-grid applications.
Nigeria, like many other developing countries, faces significant energy challenges, including inadequate power supply and reliance on non-renewable energy sources. The country’s geographical location offers a high potential for solar energy utilization. However, the adoption of solar technology is often hindered by the high initial costs and lack of efficient energy management systems. The design and implementation of cost-effective and efficient solar charge controllers can play a crucial role in overcoming these challenges, promoting the widespread use of solar energy, and contributing to sustainable development.
1.2 Statement of the Problem
Despite the proven benefits and potential of solar energy, the adoption rate in Nigeria remains relatively low. One of the significant barriers is the inefficiency of energy management systems, particularly the solar charge controllers. Many existing solar charge controllers are either too expensive or not well-suited to the specific environmental and economic conditions of Nigeria. This situation leads to underutilization of solar energy systems, reduced battery lifespan, and overall inefficiency in energy usage.
The problem is further exacerbated by the lack of locally designed and manufactured solar charge controllers, which are adapted to the unique needs of the Nigerian market. This dependency on imported systems increases costs and limits accessibility for many potential users. Therefore, there is a critical need for the development of an affordable, efficient, and reliable solar charge controller that can be easily manufactured and maintained locally. Addressing this need will enhance the adoption of solar energy systems, providing a sustainable solution to the energy crisis in Nigeria.
1.3 Aim and Objectives of the Study
The primary aim of this study is to design and implement a solar charge controller that is efficient, cost-effective, and well-suited to the Nigerian environment. To achieve this aim, the study will pursue the following objectives:
- To identify and analyze the limitations of existing solar charge controllers used in Nigeria.
- To design a solar charge controller incorporating advanced features such as MPPT and PWM, tailored to optimize performance under Nigerian climatic conditions.
- To develop a prototype of the designed solar charge controller and evaluate its performance.
- To assess the potential impact of the locally designed solar charge controller on the adoption of solar energy systems in Nigeria.
1.4 Scope and Limitations of the Study
This study focuses on the design and implementation of a solar charge controller specifically tailored for the Nigerian market. The scope includes a comprehensive analysis of existing solar charge controllers, the design and development of a new solar charge controller, and the evaluation of its performance through prototyping and testing. The study will also explore the potential socioeconomic impact of adopting the developed solar charge controller on a broader scale.
However, the study is limited by several factors, including the availability of resources for prototyping and testing, potential challenges in the local manufacturing of components, and the variability in environmental conditions across different regions of Nigeria. These limitations may affect the generalizability of the findings but provide a foundation for future research and development efforts.
1.5 Significance of the Study
The significance of this study lies in its potential to contribute to sustainable energy solutions in Nigeria. By developing a solar charge controller that is efficient, affordable, and locally manufacturable, the study addresses a critical barrier to the widespread adoption of solar energy. The successful implementation of the designed solar charge controller can lead to several benefits, including increased energy security, reduced reliance on non-renewable energy sources, and enhanced economic development through local manufacturing and job creation.
Furthermore, the study contributes to the body of knowledge in renewable energy technology, providing insights and practical solutions that can be applied in similar contexts worldwide. The findings can serve as a reference for policymakers, engineers, and researchers working towards sustainable energy solutions in developing countries.
1.6 Motivation of the project
Batteries are often blamed for power system failures, but batteries are only the most vulnerable part of the system. No battery can overcome the faults of a bad charging system. Best battery performance is achieved when the characteristics of the battery are matched to the charging source. This is the job of the charge control system. Small PV power systems at remote sites face two charge control problems that indoor float systems connected to the power grid do not. First, the amount of solar power is highly variable and influenced by uncontrollable factors such as the weather. Second, the power system may have to cope with temperature extremes. Both of these can cause too much or too little battery charging. Premature battery failure is the result.
A battery becomes overcharged when it is forced to accept more current than it can chemically store. This happens either when charging currents are too high or when the battery is fully charged and current continues to flow through the battery. Overcharging damages batteries through electrolyte water loss and grid corrosion. One of the ways a battery dissipates overcharge current is to use it to decompose electrolyte water. Water is broken down into hydrogen and oxygen gases. This process is referred to as gassing. Unless the gases are recycled or the water is replaced, the loss is permanent. Battery capacity is permanently lost when the electrolyte dries out.
In small PV systems, undercharging is as responsible as overcharging for early battery failure (Hund, 1997, p.1).
The problem with undercharging is sulfation. As a battery discharges, the active material on both plates is changed to lead sulfate. When the battery recharges, the lead sulfate is changed back to active material and sulfate ions return to the electrolyte. Sulfate ions do this easily if they are not part of a larger lead sulfate crystal structure. However, if recharge is delayed, there is time for crystal growth and it can become difficult or impossible to change the entire lead sulfate back into active material. Battery self-discharge contributes to crystal growth. By delaying full recharge, undercharging allows lead sulfate to form more perfect crystal structures. In extreme cases, surface lead sulfate crystal barriers block whole plates and the battery is unable to recharge. Such a battery is said to have “sulfated” because its plates have “hardened”.
Electrolyte freezingis another problem caused by severe undercharging. Electrolyteswith low specific gravities freeze at higher temperatures. Frozen electrolytes expand and injure plates. On the other hand, during periods of below average isolation and/or during periods of excessive electrical load usage, the energy produced by the PV array may not be sufficient to keep the battery fully recharged. When a battery is deeply discharged, the reaction in the battery occurs close to the grids, and weakens the bond between the active materials and the grids. When a battery is excessively discharged repeatedly, loss of capacity and life will eventually occur. In some cases, the electrical loads in a PV system must have sufficiently high enough voltage to operate. If batteries are too deeply discharged, the voltage falls below the operating range of the loads, and the loads may operate improperly or not at all Therefore, a charge controller is important to prevent battery overcharging, excessive discharging, reverse current flow at night and to protect the life of the batteries in a PV system. Charge controllers prevent excessive battery overcharge by interrupting or limiting the current flow from the array to the battery when the battery becomes fully charged and prevent battery over-discharge by open-circuiting the connection between the battery and system load once the battery reaches a low state of charge condition. Consequently overcharge and over-discharge effects can be removed.
Infrared Remote Controlled Home Automation System is not common in Bangladesh. But with the development of technology the world is going towards automation everywhere from industry to home. Automatic control of home appliances is highly demand now a day. In this work, we have designed and constructed a circuit which specially meet the requirement of control the home appliances through any IR remote control that is portable within the periphery of the room. The device is capable of controlling a load of high power rating from remote area.
1.7 Future scope of the project
As control of home appliances using remote control is not common in our country. The future scope in this area is vast if proper measures are taken. At present the device can only control the speed of a DC fan. In future it can be designed to control the speed of an AC fan. The designed device can be configured to work with smart phones in future. As the smart phones now has built in universal remote. With further development of the project, it is possible to develop an internet based wireless home automation system for multifunctional devices. It is also possible to develop GSM technology based home automation and SMS based control for monitoring systems.
1.8 Organization of the thesis
This project is divided into 5 chapters:
Chapter 1: An introduction of the project. Objective, purpose and future scope of the project is described in this chapter.
Chapter 2: A literature review of existing charge controller design. Some recent works related to our projectare studied. The basic elements of the proposed system are described in short.
Chapter 3: In the 3rd chapter, we have studied the theories in details related to this work.Types of charge controller regulation, two stage on/off controller, definition and families of microcontroller, the internal architecture of PIC16F77 microcontroller and battery selection are described. MCU needs to configure at first, how it should be configured is discussed in this chapter.
Chapter 4: Mainly focused on methodologies for the design, development and implementation of PhotovoltaicCharge Controller with infrared remote control scheme. This chapter also includes the working procedure of the system. Details on the progress of the project are explained in this chapter.
Chapter 5: Result for the breadboard implementation of the system is demonstrated in this chapter.
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