ABSTRACT
Nigeria is a country with an estimated population of 170 Million people, 65% of which are between the ages of 18 to 45 years, but only about 40% of the population has access to adequate electricity supply. The National grid is not enough, thus there is limited extension of the grid to most communities, and it would take decades to reach most remote areas in Nigeria. This leaves a majority of Nigerians who live in most of those communities with little or no access to electricity. Even the available electricity capacity generated is insufficient to meet existing power needs of the less than 40% who have access to the national grid which lead to instability of power system in our country. Therefore, it has become imperative for exploitation and establishment of other energy resources/infrastructure to complement and supplement the limited power generation and supply available in Nigeria. Fortunately, Nigeria is endowed with abundant natural resources of renewable energy, like the sun, wind, hydros, biomass (waste) etc. As at the moment, renewable energy will be a practical alternative to supplementing electricity supply in Nigeria. In the light of this renewable energy such as solar energy from the sun becomes a source of energy that can be used instead of procuring fossil on non-renewable energy sources. Hence, a 2.0kVA power output off grid solar powered inverter is designed and constructed with 24V DC input supply by the solar array and 220V AC output from the transformer to the loads to handle these problems. Solar inverter converts the variable direct current (DC) output of a Photovoltaic (PV) Solar Panel into a utility frequencyalternating current (AC) that can be fed into a commercial electrical grid or used by a local, off-grid electrical network. It is a critical component in a photovoltaic system, allowing the use of ordinary AC-powered equipment.In Solar inverter, Solar panels produce direct electricity with the help of electrons that are moving from negative to positive direction. Most of the appliances that we use at home work on alternative current. This AC is created by the constant back and forth of the electrons from negative to positive. In AC electricity the voltage can be adjusted according to the use of the appliance.
TABLE OF CONTENTS
Title page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of contents vi-x
List of tables x
List of figures xi
Abstract xii
CHAPTER 1: INTRODUCTION
1.1 Background of the project 1-3
1.2 Scope of the project 3
1.3 Purpose of the project 3
1.4 Problem purpose of the project 4
1.5 Significance purpose of the project 4-5
1.6 Objectives purpose of the project 5
1.7 Limitation of the project 5-6
1.8 Organization of the project 6
CHAPTER 2: REVIEW OF LITEREATURE
2.1 Historical Background of Photovoltaic Cell 7-8
2.1.1 Berman's price reductions 8-9
2.1.2 Photovoltaiccell applications 9
2.2 Theoretical Review of Solar Cell 10
2.3 Review Of Solar Cell Efficiency 10-11
2.4 Review of Solar Cell Materials 11-12
2.5 Review of Early Inverters 12
2.5.1 Controlled rectifier inverters 12-14
2.5.2 Rectifier and inverter pulse numbers 14
CHAPTER 3: MATERIALS AND METHODS
3.1 System Design 15
3.2 Material and Components 15-17
3.3 Block Diagram of a Stand-alone PV Inverter 17-18
3.4 Working Principle of the Block Diagram 18
3.4.1 AC priority mode 18
3.4.2 PV priority mode 18-19
3.5 Analysis of the Block Diagram 19
3.5.1 Solar array 19
3.5.2. Type of solar array mounting 19
3.5.2.1 Fixed mounting 19
3.5.2.2 Adjustable mounting 19
3.5.2.3 Tracking mounting 19-20
3.5.3 Solar charge controller 20
3.5.4 Features of the charge controller 20-21
3.5.5 System voltage select 21
3.5.6 Protection function 21
3.5.6.1 Battery low voltage protection (LVD) 21
3.5.6.2 Battery over-voltage disconnection (OVD) 21-22
3.5.6.3 Load over-current protection 22
3.5.6.4 High voltage disconnection protection (HVD) 22
3.6 Deep Cycle Battery 22
3.6.1 Battery connections 23
3.6.2 Battery in series 23
3.6.3 Battery in parallel 23
3.6.4 Charging time of battery using solar energy 23-24
3.6.5 Discharge durations of the battery 24-25
3.7 Design Calculation and Construction of 2kVA Inverter with Circuit Operation 26
3.7.1 The sourcing stage 26
3.7.2 The regulating stage (Power Stage) 26
3.7.3 The micro-controller stage or oscillating stage 27-31
3.7.4 The MOSFET Switching Stage or Driving Stage 31-32
3.7.4.1 Mosfet switching protection 32-34
3.7.5 The transformation stage 34
3.7.5.1 Transformation design calculations 34-38
3.7.5.2 Selection of wire gauge 38-39
3.7.6 The output stage 39
3.8 The Relay 39-40
3.9 The Change-over Stage 40
3.10 The Battery Charging Stage 40
CHAPTER 4: RESULT AND DISCUSSION
4.1 Results 41
4.2 Discussion 41
4.2.1 Solar panel testing 41-42
4.2.2 Inverter circuit testing 42
4.3 Casing and Packaging 42
4.4 Precautions and Maintenance 43
4.4.1 Inverter preventive maintenance 43-44
4.4.2 Battery maintenance 44
4.4.3 Troubleshooting 44
4.5 Problems Encountered 45
4.6 Bill of Engineering Measurement and Evaluation (BEME) 45-46
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 47
5.2 Recommendation 47-48
Reference 49-50
LIST OF TABLES
3.1 Circuit Components 16
4.1 Result Obtained from the Design Calculation 41
4.2 Inverter Problems and Solution 44
4.3 Bill of Engineering Measurement and Evaluation 45-46
LIST OF FIGURES
3.1 Symbol of resistor 17
3.2 Solar Powered Stand-alone inverter 18
3.6 Symbol of a cell and a battery 22
3.7.3 Pin Identification of PIC16F72 27
3.7.3b Circuit Diagram of 2.0kVA Sine-wave Inverter 28
3.7.4 Symbol of a P-type and N-type MOSFET. 32
3.7.4.1 Pin Out Diagram of a MOSFET Driver 34
CHAPTER 1
INTRODUCTION
Solar Inverter converts direct current (DC) output of a photovoltaic (PV) solar panel into a utility frequency alternating current (AC) that can be fed into a commercial electrical grid or used by a local, off-grid electrical network. It is a critical balance of system (BOS)–component in a photovoltaic system, allowing the use of ordinary AC-powered equipment. Solar power inverters have special functions adapted for use with photovoltaic arrays, including maximum power point tracking and anti-islanding protection.
The solar panel used in solar inverter produces direct electricity with the help of electrons that are moving from negative to positive direction. Most of the appliances that we use at home work on alternative current. This AC is created by the constant back and forth of the electrons from negative to positive. In AC electricity the voltage can be adjusted according to the use of the appliance. As solar panels only produce Direct current the solar inverter is used to convert the DC to AC.
An inverter produces square waves or a sine wave which can be used for running lights, televisions, lights, motors etc. However these inverters also produce harmonic distortion.
1.1 BACKGROUND OF THE PROJECT
Solar Technology isn’t new. Its history spans from the 7th Century B.C. to today. We started out concentrating the sun’s heat with glass and mirrors to light fires. Today, we have everything from solar-powered buildings to solar-powered vehicles. Here you can learn more about the milestones in the historical development of solar technology, century by century, and year by year. You can also glimpse the future. From the 3rd Century BC when Archimedes fought off Roman ships by concentrating the sun rays at them with brass shields (they burst into flame), through work by some of the best known figures in the history of science, harnessing the power of the sun has long been a goal of human innovation. Let’s look at some of the highlights:
In 1767 Swiss physicist, alpine explorer, and aristocrat Horace de Saussure is credited with inventing the first working solar oven, amongst other discoveries. Constructed from 5 layers of glass and measuring around 12 inches across, the oven worked by allowing light to pass through the glass before being absorbed by the black lining and turned into heat. The heat is then reflected by the glass, therefore heating the space inside the box up to 87.5 degrees Celsius.
Also in1839 Edmond Bequerel, born in Paris in 1820, discovered that when two electrodes were placed in an electrolyte (electricity-conducting solution), a voltage developed when light fell upon the electrolyte. The basic principles of solar power had been uncovered.
Many people using solar power these days which prove that its necessity has been increased in the current years. A Solar inverter is similar to a normal electric inverter but uses the energy of the Sun, that is, Solar energy. A solar inverter helps in converting the direct current into alternate current with the help of solar power. Direct power is that power which runs in one direction inside the circuit and helps in supplying current when there is no electricity. Direct currents are used for small appliance like mobile e phones, MP3 players, IPod etc. where there is power stored in the form of battery. In case of alternative current it is the power that runs back and forth inside the circuit. The alternate power is generally used for house hold appliances. A solar inverter helps devices that run on DC power to run in AC power so that the user makes use of the AC power. If you are thinking why to use solar inverter instead of the normal electric one then it is because the solar one makes use of the solar energy which is available in abundant from the Sun and is clean and pollution free.
Solar inverters are also called as photovoltaic solar inverters. These devices can help you save lot of money. The small-scale grid one have just two components i.e. the panels and inverter while the off grid systems are complicated and consists of batteries which allows users to use appliances during the night when there is no Sunlight available. The solar panel and the batteries that are placed on rooftops attract Sun rays and then convert the Sunlight into electricity. The batteries too grab the extra electricity so that it can then be used to run appliances at night.
1.2 SCOPE OF THE PROJECT
The main function of solar inverter is to convert battery's Direct Current (DC) into pure sine wave Alternative Current (AC) to feed home compliances.
Solar power inverter system is consisted of solar panels, charger controllers, inverters and rechargeable batteries, while solar DC power system is not included inverters. The inverter is a power conversion device, which can be divided into self-excited oscillation inverter and external excited oscillation inverter.
1.3 PURPOSE OF THE PROJECT
The purpose of this work is to build a power generating device that transforms direct current (DC) generated by a PV system into alternating current (AC), which can be sent into AC appliances. These inverters can be used either in concert with battery systems or to directly power certain devices. They also tend to have a few identifying features that are specifically intended to be used with Photo Voltaic arrays, such as maximum power point tracking (MPPT).
1.4 PROBLEM OF THE PROJECT
• Initially you need to shell out a lot of money for buying a solar inverter
• It will work effectively and produce direct current only when the Sunlight is strong.
• The solar panels that are used to attract Sunlight requires lots of space
• The device can work efficiently only if the presence of the Sun is strong.
• Maintenance and replacement may require more effort. In the event of a problem, a technician will need to access the roof to make repairs. Depending on your maintenance plan and warranty, this may cost you money.
1.5 SIGNIFICANCE OF THE PROJECT
Solar Inverter is useful in making appliances work at residential and industrial levels, such as:
• A Solar Inverter is better optimised for solar power than the regular one. For example, it will prioritise power supply from the solar panels. This means that when the energy from the Sun is adequate like during afternoons, the inverter will draw power entirely from the solar panels to power your home or office even if public power supply is available. This can lead to huge savings on power bills.
• Similarly, a Solar hybrid inverter will prioritise charging from solar panels, enabling your batteries to charge via the PV panels even when public power supply is on, leading also to savings on your power bills.
• Solar inverter has always helped in reducing global warming and Green House effect.
• Also use of solar inverter helps in saving money that would have used for buying fuel for conventional generator.
• Some solar inverters will allow you prioritise charging to solar panels or power grid depending the battery level. Some solar inverters are even intelligent enough just to take just as much deficit current from the grid as is required.
• A solar inverter helps in converting the Direct current in batteries into alternative current. This helps people who use limited amount of electricity.
• There is this synchronous solar inverter that helps small homeowners and power companies as they are large in size.
• Then there is this multifunction solar inverter which is the best among all and works efficiently. It converts the DC power to AC very carefully which is perfect for commercial establishments.
• Solar inverters are the best way and they are better than the normal electric ones. Also their maintenance does not cost much money.
• Solar Inverters can work when there is no Sunlight but provided their battery is charged fully with the help of Sunlight.
1.6 OBJECTIVE OF THE PROJECT
The main objective of this project is to design and construct a solar power generating device that can collect an input dc voltage (24vdc) from the solar panel and convert it to 220vac output which can be used to power ac appliances which is rated 2kW.
1.7 LIMITATION OF THE PROJECT
• The intensity of the Sun varies throughout the day. This creates an over-charging problem if the panels are connected to the battery directly, and It should also be able to tell you when you connect the panels wrongly (i.e. positive to negative, etc) and also provide protection against short-circuit. For this reason a charge controller must be used to offer protection from high voltage and current from the panels.
• The inverter frequency is rated at 50Hz
• Iron casing and good heat sink is been used for heat absorption
1.8 ORGANIZATION OF THE PROJECT
This work is organized in such a way that every reader of this work will understand how solar power inverter is been made. Starting from the chapter one to chapter five focused fully on the topic at hand.
Chapter one of this works is on the introduction to Solar Power Inverter. In this chapter, the background, significance, objective, limitation and problem of Solar Power Inverter were discussed.
Chapter two is on literature review of Solar Power Inverter. In this chapter, all the literature pertaining to this work was reviewed.
Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.
Chapter four is on testing analysis, results and discussion. All testing that result accurate functionality was analyzed.
Chapter five is on conclusion, recommendation and references
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