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DESIGN AND CONSTRUCTION OF A  3.5KVA SOLAR POWER INVERTER

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APPROVAL PAGE

This is to certify that the research work, "design and construction of a  3.5kva solar power inverter" by ---, Reg. No. EE/H2007/01430 submitted in partial fulfillment of the requirement award of a Higher National Diploma on Electrical and Electronics Engineering has been approved.

By
Engr. ---                                                     Engr. ---
Supervisor                                                  Head of Department.
Signature……………….                           Signature……………….        

……………………………….
 Engr. ---
External Invigilator



DEDICATION
This project is dedicated to Almighty God for his protection, kindness, strength over my life throughout the period and also to my --- for his financial support and moral care towards me.Also to my mentor --- for her academic advice she often gives to me. May Almighty God shield them from the peril of this world and bless their entire endeavour Amen.



ACKNOWLEDGEMENT

The successful completion of this project work could not have been a reality without the encouragement of my --- and other people. My immensely appreciation goes to my humble and able supervisor mr. --- for his kindness in supervising this project.
My warmest gratitude goes to my parents for their moral, spiritual and financial support throughout my study in this institution.
My appreciation goes to some of my lecturers among whom are Mr. ---, and Dr. ---. I also recognize the support of some of the staff of --- among whom are: The General Manager, Deputy General manager, the internal Auditor Mr. --- and the ---. Finally, my appreciation goes to my elder sister ---, my lovely friends mercy ---, ---, --- and many others who were quite helpful.


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ABSTRACT

This work is on design and construction of a solar power inverter. Solar power 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.

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      DEFINITION OF TERMS
1.9      PROJECT ORGANISATION

CHAPTER TWO
2.0     LITERATURE REVIEW
2.1      OVERVIEW OF THE STUDY
2.2      REVIEW OF AVALIABLE TECHNOLOGY
2.3      REVIEW OF THE RELATED STUDY
2.4      KNOWLEDGE GAP
2.5      HISTORITICAL BACKGROUND OF PHOTOVOTAIC CELL
2.6         THEORETICAL REVIEW OF SOLAR CELL
2.7      REVIEW OF SOLAR CELL EFFICIENCY
2.8      REVIEW OF SOLAR CELL MATERIALS
2.9      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
3.8      DESIGN CALCULATION

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
4.5      PROBLEM ENCOUNTERED
4.6      PRECAUTIONS
4.7      CONSRUCTION OF THE CASING
4.8      ECONOMIC OF THE PROJECT
4.9     PROJECT VIABILITY
4.10   PROJECT RELIABILITY
4.11   PROJECT MAINTAINABILITY
4.12      PROJECT EVALUATION

CHAPTER FIVE     
5.1      CONCLUSION
5.2      RECOMMENDATION
5.3      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].

1.1                             BACKGROUND OF THE PROJECT

The solar inverter is a vital component in a solar energy system. It performs the conversion of the variable DC output of the Photovoltaic (PV) module(s) into a clean sinusoidal 50 or 60 Hz AC current that is then applied directly to the commercial electrical grid or to a local, off-grid electrical network. A solar cell (also called photovoltaic cell) is the smallest solid-state device that converts the energy of sunlight directly into electricity through the photovoltaic effect. A Photovoltaic (PV) module is an assembly of cells in series or parallel to increase voltage and/or current. A Panel is an assembly of modules on a structure. An Array is an assembly of panels at a site. Typically, communication support scheme is included so users can monitor the inverter and report on power and operating conditions, provide firmware updates and control the inverter grid connection.
At the heart of the inverter is a real-time microcontroller. The controller executes the very precise algorithms required to invert the DC voltage generated by the solar module into AC. This controller is programmed to perform the control loops necessary for all the power management functions necessary including DC/DC and DC/AC. The controller also maximizes the power output from the PV through complex algorithms called maximum power point tracking (MPPT). The PV maximum output power is dependent on the operating conditions and varies from moment to moment due to temperature, shading, cloud cover, and time of day so adjusting for this maximum power point is a continuous process. For systems with battery energy storage, the twocontroller can control the charging as well as switch over to battery power once the sun sets or cloud cover reduces the PV output power. (Aditee P. Bapatet al 2013)

1.2 PROBLEM STATEMENT
If there is one factor that has perpetually maintained the status of Nigeria as a less developed country, it is its electricity sector.Till date, many households and industrial businesses cannot be guaranteed of 24 hours supply of electricity from the National grid. At this stage of Nigeria’s social and economic development, the country cannot deliver sufficient energy to the citizens despite huge financial resources that have been expended in the sector.
Rather, Nigerians have continued to rely on electricity generators for their power supply, fuel marketers are taking significant portion of households’ institutions of learning’and businesses’ incomes to supply power, noise pollution from regular humming generators have become integral part of living for many Nigerians with imaginable consequences on their health. The federal university of technology minna is not immune to the aforementioned problems of Nigeria’s power sector, which has led to increase in day to day running cost of the university. Because of these problems, there is a need to design and construct the hybrid solar panel inverter for the department of electrical and electronics, federal university of technology minna to complement or augment the electricity supply from the National grid, reduce cost of energy consumed and eliminate noise/environmental pollution that is associated with running of generator.

1.3                           AIM AND OBJECTIVES OF THE PROJECT

The main aim 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 output which can be use to power an ac appliances.

The objectives are as follows: -

  1. To provide efficiency, steadiness in the use of power appliances, by ensuring continuous availability of power supply in the cause of main outage during an execution of an important or urgent assignment. Thereby enabling the department meet up with its office duties even when central power is not available.
  2. Reduce load on the National grid that turn to be reduce the overall energy consumption dependency on the main energy supply in the country
  3. Decrease customer utility bill on energy utilization because of its non-fuel consumption, low price and maintenance cost as compared to the convectional sources of power supplies within International and Local market.
  4. Again, reduce carbon discharges and subsequently reduce global warming particularly in a period when poor climatic change has become a threat to human survival and life in general to all living creatures hence an ever increasing concern to control it.

    1.4                                      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.

    1.5                                              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. Solar inverter converts DC (from solar panel ) to AC for consumption purposes [9].

    1.6                                         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 [7].
  • 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 on the battery level. Some solar inverters are even intelligent enough just to take just as much deficit current from the grid as is required [7].
  • 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 [7].

1.7                                              PROBLEM OF THE PROJECT

  • Initially you need to shell out a lot of money for building a solar inverter
  • It will work effectively and produce direct current only when the Sunlight is strong.
  • The solar panels that are used for the design 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].

1.8                                           LIMITATION OF THE PROJECT

  • This device is rated 3.5kva that means any load more than 3.5kva should for no reason applied to this device.
  • 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 [5].
  • The inverter frequency is rated at 50hz
  • Iron casing and good heat sink is been used for heat absorption
  • In spite of the construction of an inverter and its noiseless and pollution free nature unlike other alternative sources of the generating electricity, there is a need for charging and recharging the battery from time to time.
  • The inability of the circuit to provide a pure sine wave output from gives room for further improvement. This is because it is quite expensive to design a pure wave inverter circuit.
  • Again, lack of financial assistance incapacitated the project to achieve its accuracy and reliability as well its appearance (packaging).

1.9                                   DEFINITION OF TERMS
Terms related to this work are defined as below:
Power Factor (PF) Control: Sets the ratio of real power to apparent power, allowing for sourcing or sinking of VARs to maintain voltage and increase efficiency in the power system.
Utility-scale PV plant: It is a installation that is ground-mounted. The plant owner sells energy directly to the electric utility. The interconnection occurs on medium or high voltage level.
Utility-scale inverter: Inverter which is used in an Utility-scale installation
Maximum input voltage (Vdcmax): allowed maximum voltage at the inverter input

Minimum input voltage (Vdcmin): minimum input voltage for the inverter to energize the utility grid, independent of mode of operation
Start-up input voltage (Vdcstart): input voltage at which the inverter starts energizing the utility grid rated input voltage (Vdc,r) input voltage specified by the manufacturer, to which other data sheet information refers
Maximum MPP voltage (Vmppmax): maximum voltage at which the inverter can deliver its rated power.
Minimum MPP voltage (Vmppmin): minimum voltage at which the inverter can deliver its rated power.
Maximum input current (Idcmax): maximum current at which the inverter can operate. If the inverter has multiple MPP inputs, Idcmax is related to each single input.
Maximum grid voltage (Vacmax): maximum voltage at which the inverter can energize the grid.
Minimum grid voltage (Vacmin): minimum voltage at which the inverter can energize the grid.
Rated grid voltage (Vac,r): utility grid voltage to which other data sheet information refers.
Maximum output current (Iacmax): maximum output current that the inverter can deliver.
Rated power (Pac,r): the active power the inverter can deliver in continuous operation
rated frequency (fr): utility grid frequency at which the inverter performs as specified.
Maximum frequency (fmax): maximum frequency at which the inverter can energize the grid.
Minimum frequency (fmin): minimum frequency at which the inverter can energize the grid.
Power factor of operation range: range of power factor for the range operation of the inverter.
Inverter: electric energy converter that changes direct electric current to single-phase or polyphase alternating current
Isolated inverter: an inverter with at least simple separation between the mains and PV circuits
Multiple mode inverter: an inverter that operates in more than one mode, for example having grid-interactive functionality when mains voltage is present, and stand-alone functionality when the mains is de-energized or disconnected
Stand-alone inverter: an inverter or inverter function intended to supply AC power to a load that is not connected to the mains.
MPPT (Maximum Power Point Tracking): Control strategy of operation at maximum power point or nearby.
PCC (Point of Common Coupling): Point of a power supply network, electrically nearest to a particular load, at which other loads are, or may be, connected. 
Maximum MPP voltage: Maximum voltage at which the EUT can convert it’s rated power under MPPT conditions.
Dry cell: A battery cell that does not contain any liquid but instead has a solid or paste electrolyte.
Duty cycle: The percentage of time that a machine or system is active. If a backup generator is used for 48 hours a year its duty cycle is 0.55%.
Deep cycle battery: A battery that is designed to be deeply discharged regularly and suffer less degradation than a normal battery of its type when doing so. Usually only used to describe lead-acid batteries and the depth of discharge they are designed for generally ranges from 45-75%.
Depth of discharge: How much of a battery’s total capacity is depleted before it is recharged again, expressed as a percentage.
Dielectric: A material that is dielectric is an electric insulator. The plastic coating around electrical wiring is an example.
Diode: An electronic component. A semiconductor that only allows the flow of electricity in one direction like the valves in your heart only allows blood to flow in one direction.
Direct current (DC): Electricity that flows in only one direction. Solar panels produce direct current. Before it can be used in our homes it has to be converted into alternating current by an inverter. Batteries can only be charged with direct current.
Discharge: When a battery outputs electrical energy it discharges and the energy stored inside it decreases. When a battery is fully discharged there is no usable energy left.
Discharge rate: How rapidly a battery is discharged.  This can be measured by C-rate.
Cathode: This is the electrode in a battery which positively charged cations move towards and negatively charged anions moves away from. 
Central inverter: usually refers to a large (MW scale) inverter that thousands of solar panels will be connected to in a very large commercial or utility-scale installation.
Charge: usually this refers to putting energy into a battery.
Charge controller: A device that regulates the charging and discharging of batteries. They generally operate to maximize battery life and prevent the depth of discharge being too great and prevent overcharging.
Charging: Putting energy into a battery.
Circuit: A loop that electricity travels through. A circuit can have one or many electrical components on it.
Conductance: How well something conducts electricity. How poorly something conducts electricity is resistance.
Conductor: Something that carries electric current.
Cost-effective: If something is worth the money you spent on it, it is cost-effective. The accounting methods businesses use to determine if something is cost-effective vary and can be quite complex.
Cost Of money: When you borrow money from a bank or other financial institution they will want you to pay interest.
Cut in: The point at which a controller activates a device.
Cut off voltage: As a battery becomes discharged the voltage of the current it supplies decreases. The cut off voltage is either the voltage at the point where the battery is fully discharged, or when a charge controller stops the discharge at a pre-set point. Most home energy storage systems have cut off voltages which prevent their batteries from being fully discharged to prolong their lives.
Current: A flow of electricity.
DC Converter: This is a device that changed DC current from one voltage to another.  A battery DC converter can allow batteries to be connected to a rooftop solar system.
DC Coupling: When there is one inverter used for both the solar and batteries. DC from the solar panels is used to charge the batteries via a DC charger.
Battery: A specially constructed case containing potential chemical energy. When a chemical reaction occurs electricity is generated and can be used to do work. In disposable batteries the chemical reaction cannot be easily reversed, so avoid using them. In rechargeable batteries the chemical reaction can be reversed by supplying electrical energy.
Battery capacity: The total amount of electrical energy a battery can provide before it is completely discharged. Battery capacity is often higher than usable capacity because many types of batteries will be damaged if they are completely discharged.
Battery case: The tough protective case that protects the battery cell or cells inside.
Battery cell: A battery can be made up of many individual units called cells. Or a battery can be a single cell, such as the small batteries you might put in a remote control or toy.
Battery cycle life: This is the number of times a battery can be fully discharged before it becomes so degraded it can only operate at 80% of its original capacity.
Battery enclosure: A cabinet or structure that holds batteries. This is important for lead-acid batteries used for home energy storage as they can take up a lot of space, require a lot of cabling, and both children and batteries operate better when kept separate from each other. Modern home energy storage systems normally do not require an enclosure as they are designed to be less dangerous and less infested with cabling.
Battery inverter: An inverter designed for use with batteries.  This is required for home energy storage if the solar inverter is not a multimode solar inverter that is compatible with the batteries used. 
Battery management system (BMS): The software and electronics that control how a battery charges and discharges.
Alternating current (AC): The type of current that is used in our homes and most transmission lines.
Alternative energy: Sources of energy that are an alternative to using fossil fuels or nuclear power. The big three are solar, wind, and hydroelectricity. Other types are geothermal, biomass, tidal, and wave power.
Ampere (A): The unit of electrical current which refers to the rate of flow of electricity.
Ampere-hour (A·h or A h or Ah): A current of one ampere produced for one hour. Lead-acid batteries used for home energy storage often have their capacity measured in ampere-hours. To determine its capacity in kilowatt-hours, multiply the ampere-hours by its voltage and then divide by 1,000. So a 100 ampere-hour 12 volt battery can output a maximum of 1.2 kilowatt-hours.

1.10                            APPLICATION OF THE PROJECT
Solar inverter is used for powering devices such as LED night lights, a cell phone charger, fridge, TV, Laptop and other sensitive equipment for domestic, office, workshop or commercial uses.

1.11                         ORGANISATION 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, aim, purpose, application, 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.

CHAPTER FIVE
CONCLUSION AND RECOMMENDATION
5.1 CONCLUSION
This thesis was designed and constructed to provide an alternative means of power supply for domestic and commercial uses. In addition, it aimed to provide solution to the epileptic nature of power supply in this country.This inverter can supply power to most household appliances for a period of time that is directly proportional to the ampere-hour rating of the battery. Finally, to achieve a longer time of power supply, battery banks and wider solar modules are recommended.
5.2 RECOMMENDATION

  1. The inverter should be design to use more than two batteries at a time connected in parallel.
  2. The charging unit should be designed to be able to deliver a high charging current, so that batteries could be charged on time.
  3. The device should be incorporated with alarm, to call the attention of the user when battery discharged.
  4. The device should be design to automatically switch OFF when battery charges are below the useable capacity.

 


CHAPTER TWO: The complete chapter two of “design and construction of a  3kva solar power inverter” is available. Order full work to download. Chapter two of “design and construction of a  3kva solar power inverter” consists of the literature review. In this chapter all the related work on “design and construction of a  3kva solar power inverter” was reviewed.

CHAPTER THREE: The complete chapter three of “design and construction of a  3kva solar power inverter” is available. Order full work to download. Chapter three of “design and construction of a  3kva solar power inverter” consists of the methodology. In this chapter all the method used in carrying out this work was discussed.

CHAPTER FOUR: The complete chapter four of “design and construction of a  3kva solar power inverter” is available. Order full work to download. Chapter four of “design and construction of a  3kva solar power inverter” consists of all the test conducted during the work and the result gotten after the whole work

CHAPTER FIVE: The complete chapter five of design and construction of a “design and construction of a  3kva solar power inverter” is available. Order full work to download. Chapter five of “design and construction of a  3kva solar power inverter” consist of conclusion, recommendation and references.



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