Design And Construction Of A Microcontroller Based Maximum Power Point Charge Controller

ABSTRACT

Solar charge controller limits the rate at which electric current is added to or drawn from solar panel to electric batteries. It prevents overcharging and may protect against overvoltage, which can reduce battery performance or lifespan, and may pose a safety risk. This paper describes a design of a charge controller to get the maximum power by using the Pulse Width Modulation (PWM) technique. In this paper PWM is controlled by the PIC Microcontroller. The work of the paper is to charge a 12 volt battery by using a 50 watt solar panel with maximum power. In this paper how maximum power can be achieved from solar panel to charge the battery through PWM signal generated by microcontroller is discussed and the experiments by taking voltage and current’s values in different time interval are shown. Finally the experimental results are illustrated in this paper.

TABLE OF CONTENTS

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

TABLE OF CONTENT

CHAPTER ONE

1.0      INTRODUCTION

1.1      BACKGROUND OF THE PROJECT

1.2      PROBLEMSTATEMENT

1.3      OBJECTIVE OF THE PROJECT

1.4      SCOPE OF THE PROJECT

1.5      PURPOSE OF THE PROJECT

1.6     SIGNIFICANCE OF THE PROJECT

1.7      PROBLEM OF THE PROJECT

1.8      LIMITATION OF THE PROJECT

1.9      PROJECT ORGANISATION

CHAPTER TWO

2.0     LITERATURE REVIEW

2.1      INTRODUCTION

2.2     REVIEW OF RELATED WORK

2.3     REVIEW OF PHOTOVOLTAIC CHARGE CONTROLLER

2.4      PHOTOVOLTAIC

2.5      DC-DC CONVERTERS

CHAPTER THREE

3.0     CONSTRUCTION METHODOLOGY

3.1      BLOCK DIAGRAM OF THE SYSTEM

3.2      SYSTEM CIRCUIT DIAGRAM

3.3      CIRCUIT OPERATION

3.4      SYSTEM FLOW CHAT

3.5      DESCRIPTION OF COMPONENTS USED

3.6      PROGRAM CODE

CHAPTER FOUR

RESULT ANALYSIS

4.0      TESTING AND RESULT ANALYSIS

4.1      INSTALLATION OF THE COMPLET DESIGN

4.2      CONSTRUCTION PROCEDURE

4.3      CASING AND PACKAGING

4.4      ASSEMBLING OF SECTIONS

4.5      TESTING OF SYSTEM OPERATION

4.6      PROBLEM ENCOUNTERED

CHAPTER FIVE

5.0      CONCLUSION

5.1      RECOMMENDATION

5.3      REFERENCES

CHAPTER ONE

1.0                                                        INTRODUCTION

1.1                                           BACKGROUND OF THE STUDY

Energy plays vital role for development in all sectors. With depletion of fossil fuels used for power generation and increase in demand for power, the gap between supply and demand is becoming more. Renewable energy sources can only provide solution to face this energy crisis. Out of renewable energy options, solar energy is the most potential source for all tropical countries. Sun radiates 180 billion MW of energy over Earth Just one hour of this energy could meet power needs of entire planet for a year. India receives 5000 Trillion KWhrs of energy from SUN per annum. This energy is clean, pollution free and inexhaustible and is available free and in abundance. Basically the components involved in solar system are PV panel, DC-DC Converter, Battery, Inverter.

The PV panel produces electrical voltage/current from solar energy. This solar panel can produce more than the rated voltage to the battery which can be dangerous to the battery due to the high radiation of the sun. In order to tackle the present energy crisis it is necessary to develop an efficient manner in which power has to be extracted from the incoming solar radiation. The use of the newest power control mechanisms called solar charge controller was invented.

Solar Charge controller is basically a voltage and/or current regulator to keep batteries from overcharging.

Photovoltaic production becomes double every two years, increasing by an average of 48 percent each year since 2002. For this reason it becomes the world’s fastest- growing energy technology [1]. Photovoltaic efficiency is very important for solar application. There are three ways to increase the efficiency of a photovoltaic (PV) system. The first way is to improve the solar cell’s efficiency. The second method is a solar panel tracking system to increase the efficiency of a PV system. Progress of solar panel tracking systems has been continuing for a number of years now. The third way is to maximize the energy conversion from the solar panel. The paper focuses on maximum power point PWM charge controller for photovoltaic application. When a solar panel is under an open circuit is able to supply a maximum voltage and there is no current, whereas under a short circuit is able to provide a maximum current with no voltage. In either case, the amount of power supplied by the solar panel is zero. The target is to develop a method whereby maximum power can be obtained from the voltage and current multiplied together.

The technology for solar photovoltaic battery charge controllers increased dynamically. PWM charging is very famous for its useful application. In previous days simple on-off regulators were used to limit battery out gassing when a solar panel produced overkill power. On the other hand, as solar systems developed it is clear now how much these simple devices hampered with the charging process. In previous, when the on-off regulators were used early battery failures, increasing load disconnects happened very frequently. For this reason, user frustrations were grown. In recent times PWM has played a significant role in solar battery charging. PWM solar chargers use the technology related to other modern high quality battery chargers. When the battery voltage reaches the regulation set point, the PWM algorithm slowly reduces the charging current to avoid heating and gassing of the battery, however the charging continues to return the maximum amount of energy to the battery in the shortest time. For that a superior charging efficiency, quick recharging, and a healthy battery at full capacity are got. The new way of solar battery charging guarantees many benefits for PWM technique. By using this technique it is possible to recover lost battery capacity and to increase the charge reception of battery. These includes the maintaining high average battery capacities (90% to 95%) compared to on-off regulated state-of- charge levels that are typically 55% to 60%. The other benefits are balancing drifting battery cells, reducing battery heating, gassing and automatically regulating for battery aging, voltage drops and temperature effects in solar systems [3]. In this paper a charge controller is designed to get the maximum power by using the PWM technique. This PWM technique is employed by the PIC Microcontroller. Here a 12 volt battery is charged by using a 50 watt solar panel with maximum power through the PWM charge controller circuit. The hardware designs, software implementation, prototype construction, flow chart of the program are discussed here. How maximum power can be achieved from solar panel to charge the battery through PWM signal generated by microcontroller is explained and the experiments by taking voltage and current’s values in different time interval are also described.

1.2                                                  PROBLEM STATEMENT

Solar panel supplies energy to the battery according to the intensity of light which means it can supply voltage more than the rated voltage of the battery which can cause damage to the battery. Solar charge controller is used to overcome this problem. Solar charge controller is used for correcting and detecting variations in the current-voltage characteristics of solar panel. By using solar charge controller, we can use solar panel with a voltage output greater than the battery system operating voltage. System’s complexity can be reduced by using solar charge controller as it has high efficiency. It can be applied for using with multiple energy sources such as water turbines or wind-power turbines, and so on. The solar panel’s output power is used for controlling DC-DC converter directly.

1.3                                   AIM AND OBJECTIVE OF THE PROJECT

The main aim of this work is to build a solar charge controlling device of 12v and 60A. At the end of this work the following objective shall be achieved:

1. An MPP solar charge controller shall be built.
2. This device will have the capacity to maintain the required voltage magnitude coming from solar panel necessary for the load or control the battery voltage supplied from solar panel.

1.4                                                  SCOPE OF THE PROJECT

The main scope of project is, the photovoltaic cells are converting the sunlight in to electricity a charge controller is used. PV cells are bundled together in modules or panels to produce higher voltages and increased power. As the sunlight varies in intensity the electricity so generated usually charges through the charge a set of batteries for storing the energy. Controller in this project is used: To generate the variable PWM for DC-DC CONVERTER, to control the battery voltage and Controlling the load variation.

1.5                                         SIGNIFICANCE OF THE PROJECT

Solar Charge controller is basically a voltage and/or current regulator to keep batteries from overcharging. It regulates the voltage and current coming from the solar panels going to the battery. Most “12 volt” panels put out about 16 to 20 volts, so if there is no regulation the batteries will be damaged from overcharging. Most batteries need around 14 to 14.5 volts to get fully charged.

Solar Charge controller may also monitor battery temperature to prevent overheating. Some charge controller systems also display data, transmit data to remote displays, and data logging to track electric flow over time.

1.6                                          APPLICATION OF THE PROJECT

Solar Charge controller circuits are used for rechargeable electronic devices such as cell phones, laptop computers, portable audio players, and uninterruptible power supplies, as well as for larger battery systems found in electric vehicles and orbiting space satellites.

1.7                                              PURPOSE OF THE PROJECT

Use of batteries with solar panels is usually not good. So to avoid failure of batteries before time solar charge controller is used. For example you have a 12 volt battery and you want to charge it with 12 volt solar panel. 12 volt solar panel outputs 17-20 volt. So these 17-20 volt may damage battery due to overcharging, because batteries maximum charging voltage is usually between 13.5-14 volt. To avoid this issue we need to develop a regulator which can control flow of charge from solar panel towards battery. Solar charge controller is used for this purpose.

1.8                                         METHODOLOGY

To achieve the aim and objectives of this work, the following are the steps involved:

1. Study of the previous work on the project so as to improve it efficiency.
2. Draw a block diagram.

• Test for continuity of components and devices,

1. Programming of the microcontroller
2. Design and calculation for the device was carried out.
3. Studying of various component used in circuit.

• Construction of the circuit was carried out.
• Finally, the whole device was cased and final test was carried out.

1.9                                        PROJECT WORK ORGANISATION

The work is organized as follows: chapter one discuses the introductory part of the work,   chapter two presents the literature review of the study,  chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.