Design And Construction Of A 1.5KVA Three Phase Solar Inverter

ABSTRACT

This work is on design and construction of a 1.5KVA three phase solar inverter. Solar inverter converts the variable 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 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.  As solar panels only produce Direct current the solar inverter is used to convert the DC to AC. The main aim of this work is to build a three phase solar inverter. This was achieved by wiring three single phase transformer in star and delta mode to produce a three phase output.

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      OBJECTIVE OF THE PROJECT

1.3      SCOPE OF THE PROJECT

1.4      PURPOSE OF THE PROJECT

1.5     SIGNIFICANCE OF THE PROJECT

1.6      PROBLEM OF THE PROJECT

1.7      LIMITATION OF THE PROJECT

1.8      PROJECT ORGANIZATION

CHAPTER TWO

2.0     LITERATURE REVIEW

2.1      HISTORICAL BACKGROUND OF PHOTOVOLTAIC CELL

2.2         THEORETICAL REVIEW OF SOLAR CELL

2.3      REVIEW OF SOLAR CELL EFFICIENCY

2.4      REVIEW OF SOLAR CELL MATERIALS

2.5      REVIEW OF EARLY INVERTERS

CHAPTER THREE

3.0     CONSTRUCTION

3.1      BASIC DESIGNS OF A SOLAR INVERTER

3.2      BLOCK DIAGRAM OF THE SYSTEM

3.3      DESCRIPTION OF SOLAR INVERTER UNITS

3.4      SYSTEM CIRCUIT DIAGRAM

3.5      CIRCUIT OPERATION

3.6      DESCRIPTION OF COMPONENTS USED

3.7      HOW TO CHOOSE THE BEST INVERTER BATTERY

CHAPTER FOUR

RESULT ANALYSIS

4.0      CONSTRUCTION PROCEDURE AND TESTING

4.1      CASING AND PACKAGING

4.2      ASSEMBLING OF SECTIONS

4.3      TESTING OF SYSTEM OPERATION

4.4      COST ANALYSIS

CHAPTER FIVE

5.0      CONCLUSION

5.1      RECOMMENDATION

5.2      REFERENCES

CHAPTER ONE

1.0                                                        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[1].

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[2] [3].

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[2].

A three-phase solar inverter is used to change the DC voltage to three-phase AC supply. Generally, these are used in high power and variable frequency drive applications like HVDC power transmission.

In a 3 phase, the power can be transmitted across the network with the help of three different currents which are out of phase with each other, whereas in single-phase inverter, the power can transmit through a single phase.

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 suns 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 [4][5].

Also in 1839 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 [4].

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 [4] [5]. 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 [4].

1.2                                             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 (12vdc) from the solar panel and convert it to 220vac to a three different output which can be use to power ac appliances which is rated 1.5kw.

1.3                                                 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. In other to produce three phase, three step-down transformer were used.

1.4                                              PURPOSE OF THE PROJECT

The purpose of this work is to produce three different out from a single 12v dc source.

• SIGNIFICANCE OF THE PROJECT

Solar inverter is useful in making appliances work at residential and industrial levels:

• With this device one can change from one phase to another when an existence phase fails.
• Simplest design, even a beginner to intermediate hobbyist can replicate this circuit.
• No need to purchase expensive three phase transformer, three “single phase step-down transformers” are enough.

1.6                                              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 [8].

1.7                                           LIMITATION OF THE PROJECT

• The output is square wave which is not suitable for many inductive loads.

1.8                                          APPLICATION OF THE PROJECT

Three-phase solar inverters are used for variable-frequency drive applications and for high power applications such as HVDC power transmission, three and single phase electric motors. A basic three-phase inverter consists of three single-phase inverter switches each connected to one of the three load terminals.

1.9                                                  DEFINITION OF TERMS

Phase Voltage: The voltage between neutral and any one of the phases in “star” configuration is called Phase Voltage.

• In this case the expected phase voltage is 220V at the output.

Line Voltage: The voltage between any two phases is called Line Voltage.

• In this case the expected phase voltage between any two phases is 440V at the output.

The delta-star (wye) transformers are commonly used for commercial and industrial purposes. Combining three single phase transformers are a common practice for manufacturing single three phase transformer for cost effectiveness and reducing the weight.

1.9                                        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 work 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. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.

REFERENCES

[1]       The Authoritative Dictionary of IEEE Standards Terms, Seventh Edition, IEEE Press, 2000,ISBN 0-7381-2601-2, page 588

[2].     James, Hahn. “Modifi ed Sine-Wave Inverter Enhanced”. Power Electronics.

[3].     Barnes, Malcolm (2003). Practical variable speed drives and power electronics. Oxford: Newnes. p. 97. ISBN 0080473911.

[4].     Rodriguez, Jose; et al. (August 2002). “Multilevel Inverters: A Survey of Topologies, Controls, and Applications”. IEEE Transactions on Industrial Electronics (IEEE) 49 (4): 724–738. doi:10.1109/TIE.2002.801052.

[5].     Owen, Edward L. (January–February 1996). “Origins of the Inverter”. IEEE Industry Applications Magazine: History Department (IEEE) 2 (1): 64–66. doi:10.1109/2943.476602.

[6].     Dr. Ulrich Nicolai, Dr. Tobias Reimann, Prof. Jürgen Petzoldt, Josef Lutz: Application Manual IGBT and MOSFET Power Modules, 1. Edition, ISLE Verlag, 1998, ISBN 3-932633-24-5.

[7]       https://www.energysage.com/solar/101/microinverters-power-optimizers-advantages-disadvantages/

[8]       http://www.doityourself.com/stry/troubleshooting-common-problems-with-a-solar-inverter.

[9]       https://en.wikipedia.org/wiki/Solar_inverter.