Design and implementation of a 1kVA inverter and Installation of a 10kVA solar system with lithium battery storage
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Sep 20, 2025
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About This Presentation
I want a 20+ slides from the uploaded 5 chapters material attached.
Slide Content
CHAPTER ONE
INTRODUCTION
Electricity is the backbone of modern civilization, powering homes, institutions, industries, and
technologies that define our way of life. As the demand for stable and sustainable energy
continues to rise, it becomes increasingly important to explore alternatives to traditional power
sources, especially in regions where energy supply is unreliable. This project focuses on
addressing the persistent power challenges faced by the Department of Electrical and Electronics
Engineering, University of Jos, through the installation of a 10kVA hybrid inverter solar power
system and the design and implementation of a 1kVA inverter system.
1.1Background of the Study
The demand for a reliable and sustainable power supply has increased globally due to population
growth, industrialization, and the rising dependence on electrical appliances. In many developing
countries, including Nigeria, power supply remains unstable, often disrupted by aging
infrastructure, limited generation capacity, and heavy reliance on fossil fuels. According to the
International Energy Agency (IEA), about 600 million people in sub-Saharan Africa lack access
to electricity, underscoring the urgent need for alternative energy solutions [1].
This energy problem is particularly critical in educational institutions, where frequent power
interruptions hinder both academic activities and administrative functions. At the University of
Jos, the Department of Electrical Engineering has been struggling with inconsistent power
supply, affecting the smooth running of its offices and lecture halls. To mitigate this, traditional
backup systems like diesel generators have been used. However, these systems are expensive to
maintain and are inefficient over prolonged periods, contributing to high operational costs and
environmental pollution.
This project proposes a solution to these energy challenges by designing and implementing a
1kVA inverter prototype and installing a 10kVA solar power system integrated with lithium-ion
battery storage. This solar energy system will reduce reliance on petrol, and provide a clean,
renewable source of power, thereby decreasing the department’s carbon footprint. Lithium-ion
batteries offer higher energy density, longer lifespan, and faster charging than traditional lead-
1
INTRODUCTION
Electricity is the backbone of modern civilization, powering homes, institutions, industries, and
technologies that define our way of life. As the demand for stable and sustainable energy
continues to rise, it becomes increasingly important to explore alternatives to traditional power
sources, especially in regions where energy supply is unreliable. This project focuses on
addressing the persistent power challenges faced by the Department of Electrical and Electronics
Engineering, University of Jos, through the installation of a 10kVA hybrid inverter solar power
system and the design and implementation of a 1kVA inverter system.
1.1Background of the Study
The demand for a reliable and sustainable power supply has increased globally due to population
growth, industrialization, and the rising dependence on electrical appliances. In many developing
countries, including Nigeria, power supply remains unstable, often disrupted by aging
infrastructure, limited generation capacity, and heavy reliance on fossil fuels. According to the
International Energy Agency (IEA), about 600 million people in sub-Saharan Africa lack access
to electricity, underscoring the urgent need for alternative energy solutions [1].
This energy problem is particularly critical in educational institutions, where frequent power
interruptions hinder both academic activities and administrative functions. At the University of
Jos, the Department of Electrical Engineering has been struggling with inconsistent power
supply, affecting the smooth running of its offices and lecture halls. To mitigate this, traditional
backup systems like diesel generators have been used. However, these systems are expensive to
maintain and are inefficient over prolonged periods, contributing to high operational costs and
environmental pollution.
This project proposes a solution to these energy challenges by designing and implementing a
1kVA inverter prototype and installing a 10kVA solar power system integrated with lithium-ion
battery storage. This solar energy system will reduce reliance on petrol, and provide a clean,
renewable source of power, thereby decreasing the department’s carbon footprint. Lithium-ion
batteries offer higher energy density, longer lifespan, and faster charging than traditional lead-
1
acid batteries, ensuring efficient storage of solar energy for use during outages or nighttime. This
will guarantee a reliable and uninterrupted power supply, improving the overall operational
efficiency of the department [2].
The shift to solar power and lithium-ion storage also aligns with global efforts to transition
towards more sustainable energy sources. While the upfront costs may be significant, the long-
term benefits, including reduced reliance on diesel fuel and lower maintenance costs, will make
this solution financially sustainable and environmentally responsible. The department will
benefit from increased energy independence and reduced operational costs, making this an ideal
solution for its current energy needs.
1.2Problem Statement
The Department of Electrical Engineering at the University of Jos has been severely impacted by
unreliable power supply, which disrupts both academic activities and administrative operations.
Despite efforts to use diesel generators as backup systems, these remain inefficient and costly
due to the continuous need for fuel, frequent repairs, and their significant environmental impact.
To address these persistent issues, the department requires a modern, sustainable, and cost-
effective solution.
1.3 Objectives of the Study
The primary aim of this study is to design and implement a sustainable off-grid power solution
for the Department of Electrical Engineering, University of Jos. This includes developing a
custom-built 1kVA inverter prototype and installing a 10kVA solar inverter system with lithium
battery storage for reliable backup power.
. 1.4 Scope of the Study
This project focuses on the design, construction, and performance evaluation of a 1kVA inverter
system, along with the installation of a 10kVA solar power setup with lithium battery storage.
The aim is to enhance energy reliability for academy and administrative activities in the
2
will guarantee a reliable and uninterrupted power supply, improving the overall operational
efficiency of the department [2].
The shift to solar power and lithium-ion storage also aligns with global efforts to transition
towards more sustainable energy sources. While the upfront costs may be significant, the long-
term benefits, including reduced reliance on diesel fuel and lower maintenance costs, will make
this solution financially sustainable and environmentally responsible. The department will
benefit from increased energy independence and reduced operational costs, making this an ideal
solution for its current energy needs.
1.2Problem Statement
The Department of Electrical Engineering at the University of Jos has been severely impacted by
unreliable power supply, which disrupts both academic activities and administrative operations.
Despite efforts to use diesel generators as backup systems, these remain inefficient and costly
due to the continuous need for fuel, frequent repairs, and their significant environmental impact.
To address these persistent issues, the department requires a modern, sustainable, and cost-
effective solution.
1.3 Objectives of the Study
The primary aim of this study is to design and implement a sustainable off-grid power solution
for the Department of Electrical Engineering, University of Jos. This includes developing a
custom-built 1kVA inverter prototype and installing a 10kVA solar inverter system with lithium
battery storage for reliable backup power.
. 1.4 Scope of the Study
This project focuses on the design, construction, and performance evaluation of a 1kVA inverter
system, along with the installation of a 10kVA solar power setup with lithium battery storage.
The aim is to enhance energy reliability for academy and administrative activities in the
2
department, while promoting the integration of renewable energy technologies. The scope is
divided into three primary components:
1. Design, Construction, and Testing of a 1kVA Inverter
I.Design:
The inverter will be designed to efficiently convert DC power to AC power with
emphasis on system protection, power quality, and control.
Key aspects include:
Selection of suitable power components such as MOSFETs, capacitors, resistors,
and a matching transformer.
II.Construction:
This phase involves:
Assembling power and control circuits,
Integration of cooling solutions to manage heat dissipation.
Housing the inverter in a protective enclosure to ensure safe operation.
III.Testing:
The inverter will undergo:
No-load and full-load performance tests.
Efficiency measurement through input-output power comparisons.
Output waveform analysis.
2. Installation of a 10kVA Solar Power System
This part of the study involves planning and implementation of a solar energy system composed
of photovoltaic panels, lithium battery storage, charge controllers, and an inverter.
Key activities include:
System Design: Determining panel configuration, charge controller type (MPPT), battery
sizing, and inverter capacity to meet the 10kVA load requirement.
Site Assessment: Evaluating environmental factors such as sunlight availability, shading,
and load demand for proper system sizing.
3
divided into three primary components:
1. Design, Construction, and Testing of a 1kVA Inverter
I.Design:
The inverter will be designed to efficiently convert DC power to AC power with
emphasis on system protection, power quality, and control.
Key aspects include:
Selection of suitable power components such as MOSFETs, capacitors, resistors,
and a matching transformer.
II.Construction:
This phase involves:
Assembling power and control circuits,
Integration of cooling solutions to manage heat dissipation.
Housing the inverter in a protective enclosure to ensure safe operation.
III.Testing:
The inverter will undergo:
No-load and full-load performance tests.
Efficiency measurement through input-output power comparisons.
Output waveform analysis.
2. Installation of a 10kVA Solar Power System
This part of the study involves planning and implementation of a solar energy system composed
of photovoltaic panels, lithium battery storage, charge controllers, and an inverter.
Key activities include:
System Design: Determining panel configuration, charge controller type (MPPT), battery
sizing, and inverter capacity to meet the 10kVA load requirement.
Site Assessment: Evaluating environmental factors such as sunlight availability, shading,
and load demand for proper system sizing.
3
Electrical Design: Designing wiring layouts with proper sizing, safety protections,
grounding, and system monitoring.
Installation and Commissioning: Installing all components, verifying electrical safety,
and testing the system for proper operation.
Compliance: Ensuring adherence to local codes and international standards during
installation and documentation.
4
grounding, and system monitoring.
Installation and Commissioning: Installing all components, verifying electrical safety,
and testing the system for proper operation.
Compliance: Ensuring adherence to local codes and international standards during
installation and documentation.
4
CHAPTER TWO
LITERATURE REVIEW
2.1 Introduction to Power Inverters
Power inverters are essential devices used to convert direct current (DC) electricity usually
obtained from batteries, solar panels, or other renewable energy sources into alternating current
(AC), enabling the operation of most household and industrial electrical appliances. Their
importance has grown significantly with the rise of renewable energy systems and backup power
solutions.
2.1.1 Working Principle of Inverters
Power inverters operate using high-speed switching components and signal modulation
techniques. The fundamental processes include:
Electronic Switching
Semiconductor switches like MOSFETs are used to rapidly alternate the flow of DC
current, creating a high frequency pulse.
Signal Modulation (PWM)
Pulse Width Modulation (PWM) techniques are employed to shape the pulsating signal
into a waveform that approximates or matches a sinusoidal AC signal.
Filtering and Output Conditioning
Filters (typically LC filters) are used to smooth out the waveform and reduce harmonic
distortion, delivering clean AC output suitable for sensitive electronics.
2.1.2 Types of Inverters
Inverters can be categorized by the type of waveform they generate. The major types include:
I.Pure Sine Wave Inverters
These inverters produce a smooth and continuous waveform similar to the utility grid.
5
LITERATURE REVIEW
2.1 Introduction to Power Inverters
Power inverters are essential devices used to convert direct current (DC) electricity usually
obtained from batteries, solar panels, or other renewable energy sources into alternating current
(AC), enabling the operation of most household and industrial electrical appliances. Their
importance has grown significantly with the rise of renewable energy systems and backup power
solutions.
2.1.1 Working Principle of Inverters
Power inverters operate using high-speed switching components and signal modulation
techniques. The fundamental processes include:
Electronic Switching
Semiconductor switches like MOSFETs are used to rapidly alternate the flow of DC
current, creating a high frequency pulse.
Signal Modulation (PWM)
Pulse Width Modulation (PWM) techniques are employed to shape the pulsating signal
into a waveform that approximates or matches a sinusoidal AC signal.
Filtering and Output Conditioning
Filters (typically LC filters) are used to smooth out the waveform and reduce harmonic
distortion, delivering clean AC output suitable for sensitive electronics.
2.1.2 Types of Inverters
Inverters can be categorized by the type of waveform they generate. The major types include:
I.Pure Sine Wave Inverters
These inverters produce a smooth and continuous waveform similar to the utility grid.
5
Ideal for: All types of devices, including sensitive electronics, medical equipment,
and appliances with motors.
Advantages: High efficiency, low harmonic distortion, compatibility with all
loads.
Disadvantages: Higher cost and complexity.
Figure 2.1: Pure Sine waveform
II. Modified Sine Wave Inverters
These generate a stepped waveform that approximates a sine wave.
Ideal for: Basic appliances and resistive loads.
Advantages: Affordable, simple design.
Disadvantages: Lower efficiency, potential for noise or malfunction in
sensitive devices.
Figure 2.2: Modified Sine waveform
6
and appliances with motors.
Advantages: High efficiency, low harmonic distortion, compatibility with all
loads.
Disadvantages: Higher cost and complexity.
Figure 2.1: Pure Sine waveform
II. Modified Sine Wave Inverters
These generate a stepped waveform that approximates a sine wave.
Ideal for: Basic appliances and resistive loads.
Advantages: Affordable, simple design.
Disadvantages: Lower efficiency, potential for noise or malfunction in
sensitive devices.
Figure 2.2: Modified Sine waveform
6
III. Square Wave Inverters
These produce a waveform with sudden transitions and high harmonic content.
Ideal for: Very simple tools or devices that do not require clean power.
Advantages: Cheapest and easiest to construct.
Disadvantages: Poor compatibility, high distortion, inefficient for modern
devices.
Figure 2.3: Square wave
2.2 Design Considerations for a 1kVA Inverter
In building our 1kVA inverter, we need to carefully plan how the system will work and what
kind of components we’ll need. The inverter’s main job is to convert DC power from a battery
into AC power that can run common household appliances. To make this work effectively, we
are considering several key factors in our design.
1. Power Rating and Load Type
The inverter is designed to supply up to 1kVA, which is equivalent to 1000 watts. This means it
should be able to power devices like fans, lights, TVs, and small electronics. We’re considering
different types of loads:
Resistive loads (e.g., bulbs, heaters)
Inductive loads (e.g., fans, motors)
Mixed loads (a combination of both)
7
These produce a waveform with sudden transitions and high harmonic content.
Ideal for: Very simple tools or devices that do not require clean power.
Advantages: Cheapest and easiest to construct.
Disadvantages: Poor compatibility, high distortion, inefficient for modern
devices.
Figure 2.3: Square wave
2.2 Design Considerations for a 1kVA Inverter
In building our 1kVA inverter, we need to carefully plan how the system will work and what
kind of components we’ll need. The inverter’s main job is to convert DC power from a battery
into AC power that can run common household appliances. To make this work effectively, we
are considering several key factors in our design.
1. Power Rating and Load Type
The inverter is designed to supply up to 1kVA, which is equivalent to 1000 watts. This means it
should be able to power devices like fans, lights, TVs, and small electronics. We’re considering
different types of loads:
Resistive loads (e.g., bulbs, heaters)
Inductive loads (e.g., fans, motors)
Mixed loads (a combination of both)
7
The components we choose must be able to handle these types of loads reliably.
2. Input and Output Requirements
Input Voltage: We are planning to use a battery system, most likely 24V DC for
simplicity, but 12V or 48V are also options depending on power needs.
Output Voltage and Frequency: The inverter will provide 220V AC at 50Hz, which is
standard for most household appliances in Nigeria.
3. Efficiency and Heat Management
To avoid wasting power, we want the inverter to be efficient, ideally around 90–95% or higher.
Efficiency also helps the battery last longer.
Because power components can heat up during operation, we will:
Use heat sinks to absorb heat
Possibly include a cooling fan for better airflow
Design the casing to allow proper ventilation
Designing this 1kVA inverter involves planning for power handling, cooling, protection, and
waveform quality. At this stage, we’re focused on understanding how each part will contribute to
the system so we can select the best components later. The goal is to build a reliable and efficient
inverter that works well with common household loads and can run safely for long periods.
2.3 Working Principle of the 10kVA Solar Installation
The 10kVA solar inverter system forms the core of the practical implementation of this project.
It is designed to deliver continuous and reliable power to the Department of Electrical
Engineering using a hybrid setup. The system comprises a solar panel array, lithium battery
bank, and a Felicity 10kVA hybrid inverter, which integrates a charging circuit, inverter
circuit, and automatic changeover function into a single compact unit.
8
2. Input and Output Requirements
Input Voltage: We are planning to use a battery system, most likely 24V DC for
simplicity, but 12V or 48V are also options depending on power needs.
Output Voltage and Frequency: The inverter will provide 220V AC at 50Hz, which is
standard for most household appliances in Nigeria.
3. Efficiency and Heat Management
To avoid wasting power, we want the inverter to be efficient, ideally around 90–95% or higher.
Efficiency also helps the battery last longer.
Because power components can heat up during operation, we will:
Use heat sinks to absorb heat
Possibly include a cooling fan for better airflow
Design the casing to allow proper ventilation
Designing this 1kVA inverter involves planning for power handling, cooling, protection, and
waveform quality. At this stage, we’re focused on understanding how each part will contribute to
the system so we can select the best components later. The goal is to build a reliable and efficient
inverter that works well with common household loads and can run safely for long periods.
2.3 Working Principle of the 10kVA Solar Installation
The 10kVA solar inverter system forms the core of the practical implementation of this project.
It is designed to deliver continuous and reliable power to the Department of Electrical
Engineering using a hybrid setup. The system comprises a solar panel array, lithium battery
bank, and a Felicity 10kVA hybrid inverter, which integrates a charging circuit, inverter
circuit, and automatic changeover function into a single compact unit.
8
In this system, solar panels generate DC power, which is fed into the MPPT charge controller
which optimizes the solar input and charges the lithium battery bank. The stored DC power is
then converted by the inverter into AC for powering the department’s electrical loads.
Explanation of System Operation
I.Solar Panels: Convert solar energy into direct current (DC).
II.MPPT Charge Control: Regulates and optimizes solar input for efficient battery
charging.
III.Felicity 10kVA Hybrid Inverter:
DC to AC Conversion: Converts stored battery power or direct solar energy to
usable AC electricity.
AC to DC Conversion: Converts AC supply from grid to direct current to charge
the battery.
Auto Changeover: Detects power availability and switches between battery, and
grid without manual intervention.
IV.Lithium Battery Bank: Stores excess solar energy for use during periods of low sunlight
or at night.
This setup ensures that solar energy is the primary power source during the day. When
insufficient, the system draws from the battery bank.
2.4 Overview of Solar Power Systems
Solar power systems have gained significant relevance in addressing energy challenges globally,
particularly in regions with unreliable electricity supply. In Nigeria, frequent power outages and
limited rural electrification have driven interest in renewable energy sources, especially solar
energy. As this project focuses on constructing a 1kVA, and installing a 10KVA inverter system,
solar power serves as the foundation for providing a clean, independent, and sustainable energy
source.
Nigeria is geographically positioned to receive high solar irradiation, with an average of
approximately 5.5 kWh/m² per day [3]. This makes solar energy not only abundant but also
9
which optimizes the solar input and charges the lithium battery bank. The stored DC power is
then converted by the inverter into AC for powering the department’s electrical loads.
Explanation of System Operation
I.Solar Panels: Convert solar energy into direct current (DC).
II.MPPT Charge Control: Regulates and optimizes solar input for efficient battery
charging.
III.Felicity 10kVA Hybrid Inverter:
DC to AC Conversion: Converts stored battery power or direct solar energy to
usable AC electricity.
AC to DC Conversion: Converts AC supply from grid to direct current to charge
the battery.
Auto Changeover: Detects power availability and switches between battery, and
grid without manual intervention.
IV.Lithium Battery Bank: Stores excess solar energy for use during periods of low sunlight
or at night.
This setup ensures that solar energy is the primary power source during the day. When
insufficient, the system draws from the battery bank.
2.4 Overview of Solar Power Systems
Solar power systems have gained significant relevance in addressing energy challenges globally,
particularly in regions with unreliable electricity supply. In Nigeria, frequent power outages and
limited rural electrification have driven interest in renewable energy sources, especially solar
energy. As this project focuses on constructing a 1kVA, and installing a 10KVA inverter system,
solar power serves as the foundation for providing a clean, independent, and sustainable energy
source.
Nigeria is geographically positioned to receive high solar irradiation, with an average of
approximately 5.5 kWh/m² per day [3]. This makes solar energy not only abundant but also
9
practical for off-grid and backup power systems. Small-scale solar installations have become
increasingly popular for homes, small businesses, and academic research projects due to their
adaptability and long-term cost-effectiveness.
A basic solar power system typically consists of solar panels, a charge controller, batteries, and
an inverter. The solar panels convert sunlight into direct current (DC) electricity. This DC power
is regulated by a charge controller to prevent overcharging or damaging the batteries. The stored
energy is then converted to alternating current (AC) using an inverter, which powers typical
household appliances and devices [4].
In the context of this 1kVA inverter project, the solar system plays a critical role in charging the
battery bank that powers the inverter. While specific components are yet to be selected, the
design will integrate solar energy to ensure that the system remains functional even in the
absence of grid power. This practical application not only supports clean energy adoption but
also demonstrates how students can contribute to solving real-life problems through engineering
innovation.
Solar power systems offer long-term benefits, including reduced electricity bills, minimal
environmental impact, and increased energy independence. However, challenges such as high
initial setup costs and dependency on sunlight necessitate careful planning and energy storage
considerations [5]. Nonetheless, with proper system sizing and design, solar power remains a
reliable option for powering inverter systems like the one proposed in this project.
2.5 Lithium Battery Storage in Solar Systems
Lithium-ion batteries have gained widespread adoption in solar energy systems due to their
superior performance characteristics. In this project, which uses a 10kVA inverter, lithium-ion
batteries have been selected for their efficiency, long lifespan, and advanced safety features.
These attributes make them ideal for storing solar energy in medium-scale applications.
2.5.1 Advantages of Lithium-Ion Batteries
10
increasingly popular for homes, small businesses, and academic research projects due to their
adaptability and long-term cost-effectiveness.
A basic solar power system typically consists of solar panels, a charge controller, batteries, and
an inverter. The solar panels convert sunlight into direct current (DC) electricity. This DC power
is regulated by a charge controller to prevent overcharging or damaging the batteries. The stored
energy is then converted to alternating current (AC) using an inverter, which powers typical
household appliances and devices [4].
In the context of this 1kVA inverter project, the solar system plays a critical role in charging the
battery bank that powers the inverter. While specific components are yet to be selected, the
design will integrate solar energy to ensure that the system remains functional even in the
absence of grid power. This practical application not only supports clean energy adoption but
also demonstrates how students can contribute to solving real-life problems through engineering
innovation.
Solar power systems offer long-term benefits, including reduced electricity bills, minimal
environmental impact, and increased energy independence. However, challenges such as high
initial setup costs and dependency on sunlight necessitate careful planning and energy storage
considerations [5]. Nonetheless, with proper system sizing and design, solar power remains a
reliable option for powering inverter systems like the one proposed in this project.
2.5 Lithium Battery Storage in Solar Systems
Lithium-ion batteries have gained widespread adoption in solar energy systems due to their
superior performance characteristics. In this project, which uses a 10kVA inverter, lithium-ion
batteries have been selected for their efficiency, long lifespan, and advanced safety features.
These attributes make them ideal for storing solar energy in medium-scale applications.
2.5.1 Advantages of Lithium-Ion Batteries
10
Lithium-ion batteries offer several technical and operational advantages that make them better
suited than traditional lead-acid batteries in solar systems:
High Energy Density
Lithium-ion batteries store more energy in less space and with less weight, making them
ideal for installations where space is limited or weight is a concern.
Longer Lifespan
These batteries typically last 5 to 10 times longer than lead-acid batteries, significantly
reducing replacement frequency and long-term system costs [6].
Deep Discharge Capability
They can be discharged to 80–90% of their capacity without sustaining damage, unlike
lead-acid batteries that degrade faster with deep discharges.
Faster Charging
Lithium-ion technology supports higher charging currents, allowing the battery to
recharge faster and be ready to supply energy when needed [7].
Minimal Maintenance
Unlike lead-acid batteries that require regular topping up with distilled water, lithium-ion
batteries are maintenance-free.
Stable Voltage Output
They maintain a more consistent voltage throughout the discharge cycle, which helps
stabilize the output of the inverter and other connected devices.
Environmentally Friendly
These batteries do not contain toxic materials like lead or acid, making them safer for the
environment and easier to dispose of responsibly [8].
Lightweight and Compact
The lower weight of lithium-ion batteries simplifies transportation and installation,
particularly in systems like the 10kVA inverter, which may be deployed in residential or
commercial buildings.
2.5.2 Battery Management System (BMS)
11
suited than traditional lead-acid batteries in solar systems:
High Energy Density
Lithium-ion batteries store more energy in less space and with less weight, making them
ideal for installations where space is limited or weight is a concern.
Longer Lifespan
These batteries typically last 5 to 10 times longer than lead-acid batteries, significantly
reducing replacement frequency and long-term system costs [6].
Deep Discharge Capability
They can be discharged to 80–90% of their capacity without sustaining damage, unlike
lead-acid batteries that degrade faster with deep discharges.
Faster Charging
Lithium-ion technology supports higher charging currents, allowing the battery to
recharge faster and be ready to supply energy when needed [7].
Minimal Maintenance
Unlike lead-acid batteries that require regular topping up with distilled water, lithium-ion
batteries are maintenance-free.
Stable Voltage Output
They maintain a more consistent voltage throughout the discharge cycle, which helps
stabilize the output of the inverter and other connected devices.
Environmentally Friendly
These batteries do not contain toxic materials like lead or acid, making them safer for the
environment and easier to dispose of responsibly [8].
Lightweight and Compact
The lower weight of lithium-ion batteries simplifies transportation and installation,
particularly in systems like the 10kVA inverter, which may be deployed in residential or
commercial buildings.
2.5.2 Battery Management System (BMS)
11
For lithium-ion batteries to operate safely and efficiently, a Battery Management System
(BMS) is required. The BMS continuously monitors the battery’s vital signs and helps prevent
system failures.
Key functions of the BMS include:
Overcharge and Over discharge Protection [8]
The BMS keeps the battery within safe voltage and current limits, avoiding damage and
reducing fire risks.
Temperature Monitoring and Thermal Control
It prevents overheating by cutting off the system if the battery temperature exceeds safe
thresholds, which is crucial for high-capacity batteries like those used with a 10kVA
inverter.
Short Circuit and Over voltage Protection
It detects and reacts to dangerous conditions like short circuits, helping to avoid
equipment failure and electrical fires.
Cell Balancing
The BMS ensures each individual battery cell charges and discharges evenly, which
enhances overall battery performance and longevity.
Humidity and Environmental Tolerance
Quality BMS designs ensure proper operation under varying environmental conditions,
which is important in regions with fluctuating weather.
Some modern lithium battery systems, such as SMA Home Storage, even come with internal
fire suppression features that reduce flame temperature and inhibit combustion during thermal
runaway [4].
2.5.3 Application in This Project
In this project’s 10kVA solar inverter system, the lithium-ion battery bank plays a critical role in
energy storage and delivery. The system will benefit from lithium's high-power density and
reliability, ensuring stable energy delivery during grid outages or low-sunlight conditions.
12
(BMS) is required. The BMS continuously monitors the battery’s vital signs and helps prevent
system failures.
Key functions of the BMS include:
Overcharge and Over discharge Protection [8]
The BMS keeps the battery within safe voltage and current limits, avoiding damage and
reducing fire risks.
Temperature Monitoring and Thermal Control
It prevents overheating by cutting off the system if the battery temperature exceeds safe
thresholds, which is crucial for high-capacity batteries like those used with a 10kVA
inverter.
Short Circuit and Over voltage Protection
It detects and reacts to dangerous conditions like short circuits, helping to avoid
equipment failure and electrical fires.
Cell Balancing
The BMS ensures each individual battery cell charges and discharges evenly, which
enhances overall battery performance and longevity.
Humidity and Environmental Tolerance
Quality BMS designs ensure proper operation under varying environmental conditions,
which is important in regions with fluctuating weather.
Some modern lithium battery systems, such as SMA Home Storage, even come with internal
fire suppression features that reduce flame temperature and inhibit combustion during thermal
runaway [4].
2.5.3 Application in This Project
In this project’s 10kVA solar inverter system, the lithium-ion battery bank plays a critical role in
energy storage and delivery. The system will benefit from lithium's high-power density and
reliability, ensuring stable energy delivery during grid outages or low-sunlight conditions.
12
Combined with a robust BMS, this setup will maximize the overall safety, efficiency, and
lifespan of the solar power system.
2.6 Challenges in Renewable Energy Systems
Renewable energy systems present several challenges that affect their efficiency, cost-
effectiveness, and long-term viability. These challenges are particularly critical when considering
the integration of solar energy technologies.
2.6.1 Efficiency Limitations in Inverters and Battery Storage
Inverters and battery storage are essential in solar energy systems, converting DC power from
panels and storing excess energy for later use. However, both components exhibit performance
inefficiencies:
Conversion Efficiency: Energy is lost during the DC-to-AC conversion, with inverter
efficiencies typically ranging from 90% to 97% [5].
Switching Losses: Power electronic switches used in inverters produce heat during
operation, contributing to energy losses.
Charge/Discharge Efficiency: Batteries experience energy loss during charge and
discharge cycles, typically achieving 80%–95% efficiency [5].
Self-Discharge: Even when idle, batteries gradually lose stored energy due to self-
discharge.
2.6.2 Cost and Accessibility of Solar Components
While the cost of solar technologies has declined in recent years, significant challenges remain:
High Initial Costs: Solar panel installations and accompanying storage solutions require
substantial upfront investments.
Energy Storage Needs: Due to sunlight variability, storage systems are essential, which
adds to the overall cost.
Space Requirements: Large installations require considerable land area, which may not
always be accessible or affordable [9].
13
lifespan of the solar power system.
2.6 Challenges in Renewable Energy Systems
Renewable energy systems present several challenges that affect their efficiency, cost-
effectiveness, and long-term viability. These challenges are particularly critical when considering
the integration of solar energy technologies.
2.6.1 Efficiency Limitations in Inverters and Battery Storage
Inverters and battery storage are essential in solar energy systems, converting DC power from
panels and storing excess energy for later use. However, both components exhibit performance
inefficiencies:
Conversion Efficiency: Energy is lost during the DC-to-AC conversion, with inverter
efficiencies typically ranging from 90% to 97% [5].
Switching Losses: Power electronic switches used in inverters produce heat during
operation, contributing to energy losses.
Charge/Discharge Efficiency: Batteries experience energy loss during charge and
discharge cycles, typically achieving 80%–95% efficiency [5].
Self-Discharge: Even when idle, batteries gradually lose stored energy due to self-
discharge.
2.6.2 Cost and Accessibility of Solar Components
While the cost of solar technologies has declined in recent years, significant challenges remain:
High Initial Costs: Solar panel installations and accompanying storage solutions require
substantial upfront investments.
Energy Storage Needs: Due to sunlight variability, storage systems are essential, which
adds to the overall cost.
Space Requirements: Large installations require considerable land area, which may not
always be accessible or affordable [9].
13
2.6.3 Environmental and Maintenance Concerns
Despite being a cleaner alternative, solar systems introduce environmental and operational
concerns:
Land Use and Habitat Disruption: Large-scale solar farms can lead to the displacement
of local flora and fauna [5].
Use of Hazardous Materials: Manufacturing solar panels involves materials like
cadmium and silicon, which require responsible handling and disposal to avoid pollution
[9].
Intermittency and Weather Dependence: Solar energy output fluctuates with weather
conditions and time of day, necessitating advanced storage and grid solutions for
consistent supply.
Panel Degradation: Over time, solar panels degrade, losing efficiency and requiring
maintenance or replacement to sustain performance [5].
2.7 Justification for the Study
This project is designed to serve a dual purpose: educational development through the
construction of a 1
kVA inverter and
practical energy deployment through the installation of a
working 10
kVA solar hybrid system.
The study is justified for the following reasons:
Hands-On Learning and Skill Development
Constructing the 1
kVA inverter helps students develop a deeper understanding of power
electronics, switching components, PWM control, and inverter architecture skills crucial
for any electrical engineer.
Meeting Real-World Energy Needs with the 10
kVA System
The installed 10
kVA inverter, powered by solar energy and backed by a lithium battery,
provides reliable and sustainable electricity for selected loads. This directly addresses the
challenge of grid instability in Nigeria, especially for institutions and residential
buildings.
14
Despite being a cleaner alternative, solar systems introduce environmental and operational
concerns:
Land Use and Habitat Disruption: Large-scale solar farms can lead to the displacement
of local flora and fauna [5].
Use of Hazardous Materials: Manufacturing solar panels involves materials like
cadmium and silicon, which require responsible handling and disposal to avoid pollution
[9].
Intermittency and Weather Dependence: Solar energy output fluctuates with weather
conditions and time of day, necessitating advanced storage and grid solutions for
consistent supply.
Panel Degradation: Over time, solar panels degrade, losing efficiency and requiring
maintenance or replacement to sustain performance [5].
2.7 Justification for the Study
This project is designed to serve a dual purpose: educational development through the
construction of a 1
kVA inverter and
practical energy deployment through the installation of a
working 10
kVA solar hybrid system.
The study is justified for the following reasons:
Hands-On Learning and Skill Development
Constructing the 1
kVA inverter helps students develop a deeper understanding of power
electronics, switching components, PWM control, and inverter architecture skills crucial
for any electrical engineer.
Meeting Real-World Energy Needs with the 10
kVA System
The installed 10
kVA inverter, powered by solar energy and backed by a lithium battery,
provides reliable and sustainable electricity for selected loads. This directly addresses the
challenge of grid instability in Nigeria, especially for institutions and residential
buildings.
14
Technology Adaptation and Localization
This project demonstrates how advanced energy technologies like lithium battery storage
can be adapted to local conditions using available components and local expertise—
setting a blueprint for future implementations.
Supports the Goals of Practical Engineering Education and Sustainable
Development
By combining practical inverter construction with real-world renewable energy
deployment, the project directly supports the aims of engineering education, energy
access, and technical innovation in the local context.
15
This project demonstrates how advanced energy technologies like lithium battery storage
can be adapted to local conditions using available components and local expertise—
setting a blueprint for future implementations.
Supports the Goals of Practical Engineering Education and Sustainable
Development
By combining practical inverter construction with real-world renewable energy
deployment, the project directly supports the aims of engineering education, energy
access, and technical innovation in the local context.
15
CHAPTER THREE
DESIGN AND METHODOLOGY
3.1Introduction
The purpose of this chapter is to highlight the various components used in the implementation of
the circuits that makes up the projects as well as outlining whatever calculation involved where
necessary. The components making up the 1kVA inverter include diodes, resistors, capacitors,
optocouplers, voltage regulators, heat sink, MOSFETs, switch and various ICs etc. While
components for the installation of the 10kVA solar power system include hybrid inverter, lithium
battery, charge controller, change over switch, cables, protection breakers etc. This chapter also
highlight the block diagram and also the circuit diagram of the inverter showing all the necessary
component used in the implementation of the solar inverter.
3.2System Design And Component Used In 1kva Inverter
The 1KVA inverter is divided into five different segments for easy implementation, the
following components mentioned below are used for the implementation of the 1KVA inverter in
respect to the different segment of the inverter:
i.The Block Diagram
ii.Oscillating Unit
iii.Drivers and Power (MOSFET) Unit
iv.Transformer Unit
v.Low Voltage Alarm Unit
3.2.1Block Diagram of 1KVA Inverter
16
DESIGN AND METHODOLOGY
3.1Introduction
The purpose of this chapter is to highlight the various components used in the implementation of
the circuits that makes up the projects as well as outlining whatever calculation involved where
necessary. The components making up the 1kVA inverter include diodes, resistors, capacitors,
optocouplers, voltage regulators, heat sink, MOSFETs, switch and various ICs etc. While
components for the installation of the 10kVA solar power system include hybrid inverter, lithium
battery, charge controller, change over switch, cables, protection breakers etc. This chapter also
highlight the block diagram and also the circuit diagram of the inverter showing all the necessary
component used in the implementation of the solar inverter.
3.2System Design And Component Used In 1kva Inverter
The 1KVA inverter is divided into five different segments for easy implementation, the
following components mentioned below are used for the implementation of the 1KVA inverter in
respect to the different segment of the inverter:
i.The Block Diagram
ii.Oscillating Unit
iii.Drivers and Power (MOSFET) Unit
iv.Transformer Unit
v.Low Voltage Alarm Unit
3.2.1Block Diagram of 1KVA Inverter
16
Figure 3.1: Block Diagram of 1KVA Inverter
3.2.2Oscillating Unit Design
An inverter is impotent without an oscillator. In this project work, a square wave relaxation
Oscillator (Astable Multivibrator) was used. It is an unstable amplifier which generates an AC
output signal at a very high frequency without requiring any externally applied input signal. Its
main functions here are to generate the required frequency (50Hz), to trigger or power the drivers
(MOSFETs), to alternates the driver by switching one side ON and the other OFF simultaneously
thereby giving AC as output at a fixed frequency, and also to ensure stability and high-quality
factor. The 20k variable resistor is used to adjust the frequency. The output signal waveform of
the oscillator determines the output signal waveform of the inverter. The output signal strength
of the oscillator is often small; hence it can only trigger or power the drivers (MOSFETs) and not
the 1kVA transformer. The circuit diagram of the Oscillator used to trigger or power the driver
(MOSFETs) is depicted in figure 3.2.
17
3.2.2Oscillating Unit Design
An inverter is impotent without an oscillator. In this project work, a square wave relaxation
Oscillator (Astable Multivibrator) was used. It is an unstable amplifier which generates an AC
output signal at a very high frequency without requiring any externally applied input signal. Its
main functions here are to generate the required frequency (50Hz), to trigger or power the drivers
(MOSFETs), to alternates the driver by switching one side ON and the other OFF simultaneously
thereby giving AC as output at a fixed frequency, and also to ensure stability and high-quality
factor. The 20k variable resistor is used to adjust the frequency. The output signal waveform of
the oscillator determines the output signal waveform of the inverter. The output signal strength
of the oscillator is often small; hence it can only trigger or power the drivers (MOSFETs) and not
the 1kVA transformer. The circuit diagram of the Oscillator used to trigger or power the driver
(MOSFETs) is depicted in figure 3.2.
17
Figure 3.2: Oscillator Circuit
Below are the various components used in the oscillating circuit:
i.CD4069: The CD4069 is a 14-pin integrated circuit (IC) that contains six
complementary metal-oxide-semiconductor (CMOS) inverter gates. It is a hex
inverter, meaning each gate inverts the logic of its input signal (e.g., HIGH becomes
LOW, and LOW becomes HIGH). This IC is known for its low power consumption,
high noise immunity, and reliability, making it suitable for applications such as
oscillators, pulse shaping, high-impedance amplifiers, and logic circuits [10].
Figure3.3: CD4069 Pin Configuration [10].
ii.RV1 (200k variable Resistor): RV1, the potentiometer, provides fine frequency
adjustment. By changing the resistance, the charging/discharging rate of C2 changes,
which directly alters the oscillation frequency. Higher RV1 resistance means slower
18
Below are the various components used in the oscillating circuit:
i.CD4069: The CD4069 is a 14-pin integrated circuit (IC) that contains six
complementary metal-oxide-semiconductor (CMOS) inverter gates. It is a hex
inverter, meaning each gate inverts the logic of its input signal (e.g., HIGH becomes
LOW, and LOW becomes HIGH). This IC is known for its low power consumption,
high noise immunity, and reliability, making it suitable for applications such as
oscillators, pulse shaping, high-impedance amplifiers, and logic circuits [10].
Figure3.3: CD4069 Pin Configuration [10].
ii.RV1 (200k variable Resistor): RV1, the potentiometer, provides fine frequency
adjustment. By changing the resistance, the charging/discharging rate of C2 changes,
which directly alters the oscillation frequency. Higher RV1 resistance means slower
18
capacitor charge/discharge which leads to lower frequency while lower RV1
resistance means faster capacitor charge/discharge which result in higher frequency.
This allows the circuit to be tuned to the desired inverter frequency, usually 50 Hz
(for Nigeria) or 60 Hz (for US standard)
iii.C2 (100nF Capacitor): C2 works with R2 and RV1 to determine the RC time
constant. This capacitor alternately charges and discharges through the resistors,
providing the time delay needed to sustain oscillations. It plays a critical role in
setting the period (T) of the output waveform.
iv.R1 (100Ω Resistor): This resistor is placed at the input of U1: A. Its functions
include: protecting the IC input from excessive current, improving stability by
preventing input voltage spikes and ensuring the inverter does not latch up due to
noise or fast transitions.
v.R2 (100kΩ Fixed Resistor): R2 is part of the timing network that controls the
frequency of oscillation. It sets a base resistance value that works with the capacitor
C2 to determine how long it takes to charge and discharge during each cycle.
vi.R3 and R4 (330 Ω Resistors): These resistors are connected at the outputs (U1:C and
U1:D). They serve as current-limiting resistors, ensuring that the output does not
deliver excessive current to the next stage (Driver unit). They also help reduce
switching noise, providing a clean and stable square wave
3.2.3Driver and Power (MOSFET) unit
The driver unit is designed using opto-isolators (optocouplers) to provide both signal
amplification and electrical isolation between the oscillator stage and the power stage
(MOSFETs).
The power unit consists of two sets of arranged 6 IRFP150N MOSFETs (i.e., 12 MOSFETs all
together) all arranged in parallel. Each MOSFET used has a maximum continuous drain current
of 42A, power rating of 160W and voltage of 100V. With 12 MOSFETs connected in parallel,
the driver has a maximum drain current of 504A, maximum power rating of 1920W. The driver
increases the strength of oscillating A.C weak signal and makes it suitable for transformer use. It
is designed to suit the required power of the transformer which is the nucleus of the inverter. It
19
resistance means faster capacitor charge/discharge which result in higher frequency.
This allows the circuit to be tuned to the desired inverter frequency, usually 50 Hz
(for Nigeria) or 60 Hz (for US standard)
iii.C2 (100nF Capacitor): C2 works with R2 and RV1 to determine the RC time
constant. This capacitor alternately charges and discharges through the resistors,
providing the time delay needed to sustain oscillations. It plays a critical role in
setting the period (T) of the output waveform.
iv.R1 (100Ω Resistor): This resistor is placed at the input of U1: A. Its functions
include: protecting the IC input from excessive current, improving stability by
preventing input voltage spikes and ensuring the inverter does not latch up due to
noise or fast transitions.
v.R2 (100kΩ Fixed Resistor): R2 is part of the timing network that controls the
frequency of oscillation. It sets a base resistance value that works with the capacitor
C2 to determine how long it takes to charge and discharge during each cycle.
vi.R3 and R4 (330 Ω Resistors): These resistors are connected at the outputs (U1:C and
U1:D). They serve as current-limiting resistors, ensuring that the output does not
deliver excessive current to the next stage (Driver unit). They also help reduce
switching noise, providing a clean and stable square wave
3.2.3Driver and Power (MOSFET) unit
The driver unit is designed using opto-isolators (optocouplers) to provide both signal
amplification and electrical isolation between the oscillator stage and the power stage
(MOSFETs).
The power unit consists of two sets of arranged 6 IRFP150N MOSFETs (i.e., 12 MOSFETs all
together) all arranged in parallel. Each MOSFET used has a maximum continuous drain current
of 42A, power rating of 160W and voltage of 100V. With 12 MOSFETs connected in parallel,
the driver has a maximum drain current of 504A, maximum power rating of 1920W. The driver
increases the strength of oscillating A.C weak signal and makes it suitable for transformer use. It
is designed to suit the required power of the transformer which is the nucleus of the inverter. It
19
drives the transformer in accordance to the output signal waveform of the oscillator. It provides
proper activation or controls the transformer to meet high current load requirement. The
MOSFETs and the transformer are both rated to the required output power of the inverter.
To prevent too much current from flowing to the ground since all the sources of the MOSFETs
are grounded and to reduce the direct current from the source entering the gate in order to
prevent the gate from damage, a 10KΩ resistor is connected at the source terminal and a 330Ω
resistor is connected at the gate terminal respectively. The drain of the first 6 set is connected to
one terminal of the primary coil of the step-up transformer, and the drain of the second 6 set is
connected to the other terminal of the primary coil. The two gate terminals goes to the oscillator
and the entire source terminals are joined together and connected to the negative terminal of the
24V battery.
Figure 3.4: Driver and Power (MOSFET) Circuit.
Components used in the driver and power circuit includes:
i.Optocouplers (4N35): These are opto-isolators, they electrically isolate the oscillator
circuit from power switching circuit [11]. The LED inside the optocoupler lights up when
driven by the oscillator signal and the phototransistor inside the optocoupler switches
ON, passing the signal to the MOSFET driver stage. It main advantage is that it protects
the oscillator circuit from high-voltage spikes from the MOSFET side.
ii.Voltage Regulator (LM7812): The LM7812 is a 12 V linear voltage regulator. It provides
a stable 12 V DC supply for driving the optocouplers and MOSFET gates. Since
20
proper activation or controls the transformer to meet high current load requirement. The
MOSFETs and the transformer are both rated to the required output power of the inverter.
To prevent too much current from flowing to the ground since all the sources of the MOSFETs
are grounded and to reduce the direct current from the source entering the gate in order to
prevent the gate from damage, a 10KΩ resistor is connected at the source terminal and a 330Ω
resistor is connected at the gate terminal respectively. The drain of the first 6 set is connected to
one terminal of the primary coil of the step-up transformer, and the drain of the second 6 set is
connected to the other terminal of the primary coil. The two gate terminals goes to the oscillator
and the entire source terminals are joined together and connected to the negative terminal of the
24V battery.
Figure 3.4: Driver and Power (MOSFET) Circuit.
Components used in the driver and power circuit includes:
i.Optocouplers (4N35): These are opto-isolators, they electrically isolate the oscillator
circuit from power switching circuit [11]. The LED inside the optocoupler lights up when
driven by the oscillator signal and the phototransistor inside the optocoupler switches
ON, passing the signal to the MOSFET driver stage. It main advantage is that it protects
the oscillator circuit from high-voltage spikes from the MOSFET side.
ii.Voltage Regulator (LM7812): The LM7812 is a 12 V linear voltage regulator. It provides
a stable 12 V DC supply for driving the optocouplers and MOSFET gates. Since
20
MOSFETs need a steady gate-to-source voltage (Vgs) of about 10–12 V for full
conduction, this regulator ensures consistent gate drive [12].
iii.Diodes (D1, D2 – 1N4148): These are fast-switching diodes placed across the
optocoupler outputs. They prevent reverse current and voltage transients that may occur
during switching, thereby protecting the MOSFET gates [13].
iv.Ground Resistors (R6, R8 – 10kΩ): These resistors are connected between the MOSFET
gate and ground. They act as pull-down resistors, ensuring the MOSFETs remain OFF
when no signal is applied and also prevent accidental turn-on due to gate capacitance or
noise.
v.Gate Series Resistors (R20, R21, R22, R16, R18, R24, R26, R23, R17, R19, R25, R27 –
100 Ω each): Each MOSFET gate has its own gate resistor to limits inrush current during
gate charging/discharging and also prevents oscillations or ringing in the MOSFET gate
ensuring stable switching and reduces EMI (electromagnetic interference)
vi.MOSFETs (Q2, Q3, Q4, Q6, Q9, Q10, Q11, Q12, Q7, Q8, Q13, Q14 – IRFP150N):
These are N-channel Power MOSFETs arranged in two groups (upper bank and lower
bank), they act as electronic switches that alternately connect the DC supply from the
battery to the primary winding of the inverter transformer. Multiple MOSFETs are
connected in parallel to share current, since a single MOSFET cannot handle the full load
of a 1 kVA inverter. The optocoupler drives one bank of MOSFETs while the other is
OFF. This alternating action produces a pulsating DC waveform across the transformer
primary. The transformer then steps this up to 220 VAC output.
3.2.4Transformer Unit
The transformer used for this project work is a single-phase transformer of 1kVA, 24V – 0 – 24V
at the primary windings and 220V at the secondary winding. It is a center – tapped transformer
with two terminals each common to the center – tapped terminal. Also, it is air cooled and has a
frequency of 50Hz. The drains of the drivers (MOSFETs) are connected to the terminal of the
transformer; and the center – tapped terminal is connected to the battery. The transformer is
designed to deliver an output voltage of 220V.
During inverter operation, the transformer steps up the 24V from the battery and supplies an
output of 220V
21
conduction, this regulator ensures consistent gate drive [12].
iii.Diodes (D1, D2 – 1N4148): These are fast-switching diodes placed across the
optocoupler outputs. They prevent reverse current and voltage transients that may occur
during switching, thereby protecting the MOSFET gates [13].
iv.Ground Resistors (R6, R8 – 10kΩ): These resistors are connected between the MOSFET
gate and ground. They act as pull-down resistors, ensuring the MOSFETs remain OFF
when no signal is applied and also prevent accidental turn-on due to gate capacitance or
noise.
v.Gate Series Resistors (R20, R21, R22, R16, R18, R24, R26, R23, R17, R19, R25, R27 –
100 Ω each): Each MOSFET gate has its own gate resistor to limits inrush current during
gate charging/discharging and also prevents oscillations or ringing in the MOSFET gate
ensuring stable switching and reduces EMI (electromagnetic interference)
vi.MOSFETs (Q2, Q3, Q4, Q6, Q9, Q10, Q11, Q12, Q7, Q8, Q13, Q14 – IRFP150N):
These are N-channel Power MOSFETs arranged in two groups (upper bank and lower
bank), they act as electronic switches that alternately connect the DC supply from the
battery to the primary winding of the inverter transformer. Multiple MOSFETs are
connected in parallel to share current, since a single MOSFET cannot handle the full load
of a 1 kVA inverter. The optocoupler drives one bank of MOSFETs while the other is
OFF. This alternating action produces a pulsating DC waveform across the transformer
primary. The transformer then steps this up to 220 VAC output.
3.2.4Transformer Unit
The transformer used for this project work is a single-phase transformer of 1kVA, 24V – 0 – 24V
at the primary windings and 220V at the secondary winding. It is a center – tapped transformer
with two terminals each common to the center – tapped terminal. Also, it is air cooled and has a
frequency of 50Hz. The drains of the drivers (MOSFETs) are connected to the terminal of the
transformer; and the center – tapped terminal is connected to the battery. The transformer is
designed to deliver an output voltage of 220V.
During inverter operation, the transformer steps up the 24V from the battery and supplies an
output of 220V
21
Output power of the transformer
Output power = V
s
×I
s
×cosθ , Watt. - - (1)
Where;
V
s = Secondary voltage of transformer
I
s = Secondary current of transformer
cosθ = Power factor
P
s = apparent power.
But P
s =I
s V
s - - (2)
For P
s = 1000VA (output power) andV
s = 220V.
Using (2), I
s = 4.55A.
And using (1), with P
s, V
s and I
s, cosθ = 0.9
Substituting the value of cosθ into (1), the output power (in Watts) in terms of the power factor
is V
s × I
s× cosθ = 220 ×4.55 × 0.9 = 900.9Watts.
Also, from (2), the output power rating (in Volt-Ampere) in terms of the power factor is:
Output Power (in VA) =
outputpower(¿Watts)
Cosθ
=
900.9
0.9
= 1001 VA = 1.001kVA
Transformer Turns/Windings determination
A transformer has two or more windings of insulated copper wire over an iron core. They are:
one primary winding and one or more secondary windings. Each winding is electrically isolated
from the other, but they are magnetically coupled with the help of a laminated iron core. Small
transformers have a shell type construction, i.e., the windings are surrounded by the core area.
The power delivered by the secondary is actually transferred from the primary, but at a voltage
level determined by the turn’s ratio of the two windings.
22
Output power = V
s
×I
s
×cosθ , Watt. - - (1)
Where;
V
s = Secondary voltage of transformer
I
s = Secondary current of transformer
cosθ = Power factor
P
s = apparent power.
But P
s =I
s V
s - - (2)
For P
s = 1000VA (output power) andV
s = 220V.
Using (2), I
s = 4.55A.
And using (1), with P
s, V
s and I
s, cosθ = 0.9
Substituting the value of cosθ into (1), the output power (in Watts) in terms of the power factor
is V
s × I
s× cosθ = 220 ×4.55 × 0.9 = 900.9Watts.
Also, from (2), the output power rating (in Volt-Ampere) in terms of the power factor is:
Output Power (in VA) =
outputpower(¿Watts)
Cosθ
=
900.9
0.9
= 1001 VA = 1.001kVA
Transformer Turns/Windings determination
A transformer has two or more windings of insulated copper wire over an iron core. They are:
one primary winding and one or more secondary windings. Each winding is electrically isolated
from the other, but they are magnetically coupled with the help of a laminated iron core. Small
transformers have a shell type construction, i.e., the windings are surrounded by the core area.
The power delivered by the secondary is actually transferred from the primary, but at a voltage
level determined by the turn’s ratio of the two windings.
22
To design the inverter system’s transformer of 1000VA rating, using a 24V battery as the input
and needing 220V as the output. We divide 1000 by 24 which gives 41.67Amps, this becomes
the required primary current.
The primary side of the transformer is connected to the DC battery, while the secondary side
serves the 220V AC side.
The available data are:
Secondary voltage = 220Volts
Primary Current (output current) = 41.67Amps.
Primary Voltage (output voltage) = 24 – 0 – 24 volts
Output frequency = 50Hz
Transformer turns ratio n =
N
p
N
s
=
V
p
V
s
The number of turns on the primary and secondary winding is decided by the volt per turns ratio:
Using 0.5 volt per turn
V
N
= 0.5 volt per turn
Primary Turns:
N
p
¿
1
V
N
×V
p
N
p ¿2×24=48turns
Secondary Turns:
N
s
¿
1
V
N
×V
s
23
and needing 220V as the output. We divide 1000 by 24 which gives 41.67Amps, this becomes
the required primary current.
The primary side of the transformer is connected to the DC battery, while the secondary side
serves the 220V AC side.
The available data are:
Secondary voltage = 220Volts
Primary Current (output current) = 41.67Amps.
Primary Voltage (output voltage) = 24 – 0 – 24 volts
Output frequency = 50Hz
Transformer turns ratio n =
N
p
N
s
=
V
p
V
s
The number of turns on the primary and secondary winding is decided by the volt per turns ratio:
Using 0.5 volt per turn
V
N
= 0.5 volt per turn
Primary Turns:
N
p
¿
1
V
N
×V
p
N
p ¿2×24=48turns
Secondary Turns:
N
s
¿
1
V
N
×V
s
23
N
s = 2 × 220 = 440turns
Turns Ratio:
turns ratio n =
N
p
N
s
=
V
p
V
s
=
440
48
=9.17
Winding Current
Primary current = I
P=
P
V
P
=
1000
24
=41.67A
Secondary current = I
S=
P
V
S
=
1000
220
=4.45A
Conductor cross sectional area A =
I
J
J = current density = 3 A/mm
2
Primary conductor A
P =
I
p
J
=
41.67
3
= 13.89 mm
2
Secondary conductor A
s =
I
s
J
=
4.45
3
= 1.48 mm
2
3.2.5Low Voltage Alarm Unit
Low battery alarm circuit is designed to give audio indication using a buzzer for low battery
condition during operation [14]. This ensures that the battery does not get over-discharged,
which could lead to reduced battery life, damage to inverter components and instability of
operation. The design utilizes a comparator (LM358), a 555 Timer (NE555), and a buzzer to
achieve this functionality.
24
s = 2 × 220 = 440turns
Turns Ratio:
turns ratio n =
N
p
N
s
=
V
p
V
s
=
440
48
=9.17
Winding Current
Primary current = I
P=
P
V
P
=
1000
24
=41.67A
Secondary current = I
S=
P
V
S
=
1000
220
=4.45A
Conductor cross sectional area A =
I
J
J = current density = 3 A/mm
2
Primary conductor A
P =
I
p
J
=
41.67
3
= 13.89 mm
2
Secondary conductor A
s =
I
s
J
=
4.45
3
= 1.48 mm
2
3.2.5Low Voltage Alarm Unit
Low battery alarm circuit is designed to give audio indication using a buzzer for low battery
condition during operation [14]. This ensures that the battery does not get over-discharged,
which could lead to reduced battery life, damage to inverter components and instability of
operation. The design utilizes a comparator (LM358), a 555 Timer (NE555), and a buzzer to
achieve this functionality.
24
Figure3.5: Low voltage alarm circuit.
Below are the components used in the low voltage alarm circuit:
i.Resistors R11 (10k) and RV2 (100K potentiometer) form a voltage divider network
that samples the input voltage. The potentiometer RV2 allows fine adjustment of the
sensing threshold.
ii.Zener Diode (1N4734A, 5.6V): It provide a reference voltage to the inverting input of
the comparator, it is use to ensure stable comparison by giving a fixed threshold
independent of battery fluctuation
iii.LM358 op-amp: This is a comparator; it Compares the battery voltage with a preset
reference voltage. This is the heart of the circuit since it “decides” when the battery is
low.
iv.NE555 Timer: Acts as a signal processor and driver for the buzzer. It is configured so
that when triggered by the comparator output, it sends a HIGH output to the buzzer.
v.C1 (100µF): It is use to provide timing and filtering for the NE555 timer, it ensures
stable operation and prevents noise from causing false alarm.
vi.R14 & R15 (10kΩ each): This are the Pull-up/pull-down resistors for stable operation
of the NE555, they Prevents floating inputs that may cause the timer to misfire
25
Below are the components used in the low voltage alarm circuit:
i.Resistors R11 (10k) and RV2 (100K potentiometer) form a voltage divider network
that samples the input voltage. The potentiometer RV2 allows fine adjustment of the
sensing threshold.
ii.Zener Diode (1N4734A, 5.6V): It provide a reference voltage to the inverting input of
the comparator, it is use to ensure stable comparison by giving a fixed threshold
independent of battery fluctuation
iii.LM358 op-amp: This is a comparator; it Compares the battery voltage with a preset
reference voltage. This is the heart of the circuit since it “decides” when the battery is
low.
iv.NE555 Timer: Acts as a signal processor and driver for the buzzer. It is configured so
that when triggered by the comparator output, it sends a HIGH output to the buzzer.
v.C1 (100µF): It is use to provide timing and filtering for the NE555 timer, it ensures
stable operation and prevents noise from causing false alarm.
vi.R14 & R15 (10kΩ each): This are the Pull-up/pull-down resistors for stable operation
of the NE555, they Prevents floating inputs that may cause the timer to misfire
25
vii.BUZ1 – Buzzer: This provides an audible alert when the battery voltage falls below
the threshold. This is the output stage of the circuit, warning the user to take action
3.3CIRCUIT DESIGN AND IMPLEMENTAION
3.3.1Circuit Schematics of the Inverter System
Figure 3.6: Inverter System circuit
Figure 3.4 shows the complete circuit diagram of the 1kVA inverter circuit. The oscillator is the
nucleus of the inverter circuit. Its main functions are to generate the required frequency (50Hz)
needed to trigger the drivers (MOSFETs) by switching one side ON and the other OFF
simultaneously thereby giving AC as output at a fixed frequency. The 200k variable resistor
adjusts the frequency. The output signal strength of the oscillator powers the MOSFETs and not
the 1kVA transformer. The MOSFETs has two banks which make up the drivers. The alternating
pulse output from the oscillator is fed to the MOSFETs banks. This increases the strength of the
oscillating ac weak signal and makes it suitable to switch the dc voltage at the primary of the
centered tapped transformer which serves as the step – up transformer to create the alternating
voltage effect and change in flux needed for transformation by the transformer. The transformer
then steps up the now converted 24 V D.C to 220 V A.C. The Low Battery charge detector is a
supervisory circuit. It consists of a comparator. The comparator detects the low battery charge
voltage set by Zener diode and signal the 555 timer to activate the buzzer.
26
the threshold. This is the output stage of the circuit, warning the user to take action
3.3CIRCUIT DESIGN AND IMPLEMENTAION
3.3.1Circuit Schematics of the Inverter System
Figure 3.6: Inverter System circuit
Figure 3.4 shows the complete circuit diagram of the 1kVA inverter circuit. The oscillator is the
nucleus of the inverter circuit. Its main functions are to generate the required frequency (50Hz)
needed to trigger the drivers (MOSFETs) by switching one side ON and the other OFF
simultaneously thereby giving AC as output at a fixed frequency. The 200k variable resistor
adjusts the frequency. The output signal strength of the oscillator powers the MOSFETs and not
the 1kVA transformer. The MOSFETs has two banks which make up the drivers. The alternating
pulse output from the oscillator is fed to the MOSFETs banks. This increases the strength of the
oscillating ac weak signal and makes it suitable to switch the dc voltage at the primary of the
centered tapped transformer which serves as the step – up transformer to create the alternating
voltage effect and change in flux needed for transformation by the transformer. The transformer
then steps up the now converted 24 V D.C to 220 V A.C. The Low Battery charge detector is a
supervisory circuit. It consists of a comparator. The comparator detects the low battery charge
voltage set by Zener diode and signal the 555 timer to activate the buzzer.
26
3.3.2Simulation Software Used
For the simulation of the 1kVA inverter, Proteus Design Suite was used because of its robust
features for power electronics and embedded system design. The software provides schematic
capture, SPICE-based circuit simulation, and virtual instruments such as oscilloscopes and
multimeters that make it possible to test and analyze inverter performance before hardware
implementation. Proteus also supports microcontroller co-simulation, which allows easy testing
of PWM control strategies for driving the inverter switches.
In this project, the inverter’s power stage, including the MOSFET switches, transformer, and
load, was modeled in Proteus. The simulation enabled observation of switching waveforms,
output voltage, and current characteristics under different load conditions. This not only reduced
the risk of hardware faults but also ensured that the inverter design met the required performance
specifications in a safe and cost-effective manner.
27
For the simulation of the 1kVA inverter, Proteus Design Suite was used because of its robust
features for power electronics and embedded system design. The software provides schematic
capture, SPICE-based circuit simulation, and virtual instruments such as oscilloscopes and
multimeters that make it possible to test and analyze inverter performance before hardware
implementation. Proteus also supports microcontroller co-simulation, which allows easy testing
of PWM control strategies for driving the inverter switches.
In this project, the inverter’s power stage, including the MOSFET switches, transformer, and
load, was modeled in Proteus. The simulation enabled observation of switching waveforms,
output voltage, and current characteristics under different load conditions. This not only reduced
the risk of hardware faults but also ensured that the inverter design met the required performance
specifications in a safe and cost-effective manner.
27
3.4SYSTEM DESIGN AND COMPONENTS USED IN 10KVA HYBRID SOLAR
INSTALLATION
3.4.1Block Diagram
Figure 3.7: Block Diagram of the 10kVA Solar Power Installation System
3.4.2Energy calculation
For the design of the 10 kVA Solar Power System with Lithium Battery Storage to be installed at
the Department of Electrical and Electronics Engineering, University of Jos, an accurate
estimation of the daily load requirement is necessary. This estimation serves as the foundation
for sizing the inverter, solar panels, and battery storage.
The appliances considered include essential equipment used in the departmental offices,
classrooms, and laboratories. To ensure reliability, an additional 25% power margin is
incorporated to account for future expansion, unforeseen load growth, or power surges.
The following table shows the daily energy consumption of an electrical Electronics department,
28
INSTALLATION
3.4.1Block Diagram
Figure 3.7: Block Diagram of the 10kVA Solar Power Installation System
3.4.2Energy calculation
For the design of the 10 kVA Solar Power System with Lithium Battery Storage to be installed at
the Department of Electrical and Electronics Engineering, University of Jos, an accurate
estimation of the daily load requirement is necessary. This estimation serves as the foundation
for sizing the inverter, solar panels, and battery storage.
The appliances considered include essential equipment used in the departmental offices,
classrooms, and laboratories. To ensure reliability, an additional 25% power margin is
incorporated to account for future expansion, unforeseen load growth, or power surges.
The following table shows the daily energy consumption of an electrical Electronics department,
28
University of Jos, plateau State, Nigeria.
APPLIANCE NUMBER
OF
APPLIANCE
WATTAGE
PER UNIT
(W)
TOTAL
WATTAGE
(W)
HOURS
USED PER
DAY (HRS)
ENERGY
(Wh) PER
DAY
LED BULB 43 10 430 8 3440
LAPTOPS
CHARGER
19 65 1235 8 9880
PROJECTOR 3 200 600 2 1200
PHONE
CHARGER
20 5 100 2 200
PRINTER 2 200 400 0.5 200
TRAINERS
TPS (lab
trainers)
5 100 500 3 1500
TOTAL 3,265 16,420
The total WATTAGE of the department building in this case study is about 3.265 kW,
3.4.3Inverter Capacity
An inverter is a device that converts DC power into AC power. The input rating of the inverter
ought to never be lower than the total watt of appliances. The inverter must have an equivalent
nominal voltage as your battery [15].
For stand-alone systems, the inverter must be sufficiently extensive to deal with the total amount
of Watts you will use at one time [16]. The inverter size ought to be 25-30% greater than total
29
APPLIANCE NUMBER
OF
APPLIANCE
WATTAGE
PER UNIT
(W)
TOTAL
WATTAGE
(W)
HOURS
USED PER
DAY (HRS)
ENERGY
(Wh) PER
DAY
LED BULB 43 10 430 8 3440
LAPTOPS
CHARGER
19 65 1235 8 9880
PROJECTOR 3 200 600 2 1200
PHONE
CHARGER
20 5 100 2 200
PRINTER 2 200 400 0.5 200
TRAINERS
TPS (lab
trainers)
5 100 500 3 1500
TOTAL 3,265 16,420
The total WATTAGE of the department building in this case study is about 3.265 kW,
3.4.3Inverter Capacity
An inverter is a device that converts DC power into AC power. The input rating of the inverter
ought to never be lower than the total watt of appliances. The inverter must have an equivalent
nominal voltage as your battery [15].
For stand-alone systems, the inverter must be sufficiently extensive to deal with the total amount
of Watts you will use at one time [16]. The inverter size ought to be 25-30% greater than total
29
watts of the appliances. Inverter size should be at least 3 times the capacity of those loads like
motor, refrigerator or any load with high starting current [17].
P
I
=∑wattages+25%ExtraPower
Power rating of an inverter is related to the real power that is delivered by the output of the
inverter and it is given by the expression “POWER FACTOR” [18].
PF=
Deliverablerealpower
Powerratingoftheinverter
Real power is the power that is consumed for work on load (P
I) and is calculated from the
equation (Capacity of the Inverter). Value of power factor is generally taken as 0.8
I.Inverter Design;
The inverter rating can be gotten from;
P
I
=∑wattages+¿25%ExtraPower¿
P
I
=¿ 3265 + 816.25
P
I=¿ 4081.25W = 4.0813 kW
P
KVA
=
P
I
PF(PowerFactor)
P
KVA=
4081.25
0.8
P
KVA
=5101.56≈6000VA=6KVA
Therefore, an inverter of 6kVA and above would be needed for this design. For this project a
10kVA inverter with 48V input voltage and 220V output voltage was used.
3.4.4Battery Capacity
30
motor, refrigerator or any load with high starting current [17].
P
I
=∑wattages+25%ExtraPower
Power rating of an inverter is related to the real power that is delivered by the output of the
inverter and it is given by the expression “POWER FACTOR” [18].
PF=
Deliverablerealpower
Powerratingoftheinverter
Real power is the power that is consumed for work on load (P
I) and is calculated from the
equation (Capacity of the Inverter). Value of power factor is generally taken as 0.8
I.Inverter Design;
The inverter rating can be gotten from;
P
I
=∑wattages+¿25%ExtraPower¿
P
I
=¿ 3265 + 816.25
P
I=¿ 4081.25W = 4.0813 kW
P
KVA
=
P
I
PF(PowerFactor)
P
KVA=
4081.25
0.8
P
KVA
=5101.56≈6000VA=6KVA
Therefore, an inverter of 6kVA and above would be needed for this design. For this project a
10kVA inverter with 48V input voltage and 220V output voltage was used.
3.4.4Battery Capacity
30
Energy storage is a critical part of any solar power installation. The choice of battery technology
determines not only the reliability and performance of the system, but also its lifetime cost and
efficiency. Among the available options, lithium-ion batteries have emerged as the most suitable
for solar photovoltaic (PV) systems, replacing traditional lead-acid batteries in many modern
applications.
Lithium-ion batteries
Lithium-ion batteries are highly preferable for solar power installations because they offer
several advantages over traditional lead-acid batteries, making them more efficient, durable, and
cost-effective in the long term. With a higher depth of discharge (80–90%) compared to lead-
acid’s ~50%, lithium batteries provide more usable energy from the same rated capacity, which
is crucial for longer backup in solar systems. They also have a much longer cycle life, typically
2000–5000 cycles versus 300–800 for lead-acid, reducing the frequency and cost of replacement
over the system’s lifespan [19]. Their higher energy density (150–250Wh/kg compared to 30–
50Wh/kg) means they are lighter and more compact, which is beneficial in rooftop or space-
limited solar installations. In addition, lithium-ion batteries have superior round-trip efficiency
(90–95%) compared to lead-acid (70–85%), ensuring more of the solar energy harvested is
actually stored and available for use [20]. They are also maintenance-free, unlike lead-acid
which requires regular water refilling and monitoring, and they present no risk of acid leakage or
harmful gas emissions, making them safer and more environmentally friendly. Furthermore,
lithium batteries can be charged faster, allowing maximum utilization of limited sunlight hours,
and they exhibit low self-discharge (1–3% per month) compared to 5–10% for lead-acid,
ensuring better reliability during cloudy days or seasonal variations. Although their initial cost is
higher, the combination of longer service life, higher efficiency, and lower maintenance makes
lithium-ion batteries the most economical and reliable choice for solar photovoltaic energy
storage systems
I.Required Number of Batteries
The system has the following parameters:
Daily Energy (Wh) = 16,420Wh,
1 day of autonomy,
31
determines not only the reliability and performance of the system, but also its lifetime cost and
efficiency. Among the available options, lithium-ion batteries have emerged as the most suitable
for solar photovoltaic (PV) systems, replacing traditional lead-acid batteries in many modern
applications.
Lithium-ion batteries
Lithium-ion batteries are highly preferable for solar power installations because they offer
several advantages over traditional lead-acid batteries, making them more efficient, durable, and
cost-effective in the long term. With a higher depth of discharge (80–90%) compared to lead-
acid’s ~50%, lithium batteries provide more usable energy from the same rated capacity, which
is crucial for longer backup in solar systems. They also have a much longer cycle life, typically
2000–5000 cycles versus 300–800 for lead-acid, reducing the frequency and cost of replacement
over the system’s lifespan [19]. Their higher energy density (150–250Wh/kg compared to 30–
50Wh/kg) means they are lighter and more compact, which is beneficial in rooftop or space-
limited solar installations. In addition, lithium-ion batteries have superior round-trip efficiency
(90–95%) compared to lead-acid (70–85%), ensuring more of the solar energy harvested is
actually stored and available for use [20]. They are also maintenance-free, unlike lead-acid
which requires regular water refilling and monitoring, and they present no risk of acid leakage or
harmful gas emissions, making them safer and more environmentally friendly. Furthermore,
lithium batteries can be charged faster, allowing maximum utilization of limited sunlight hours,
and they exhibit low self-discharge (1–3% per month) compared to 5–10% for lead-acid,
ensuring better reliability during cloudy days or seasonal variations. Although their initial cost is
higher, the combination of longer service life, higher efficiency, and lower maintenance makes
lithium-ion batteries the most economical and reliable choice for solar photovoltaic energy
storage systems
I.Required Number of Batteries
The system has the following parameters:
Daily Energy (Wh) = 16,420Wh,
1 day of autonomy,
31
System Efficiency = 90%,
95% Depth of Discharge.
Therefore;
Total Battery Capacity (Wh) =
DailyEnergy(Wh)×DaysofAutonomy
SystemEfficiency×DepthofDischarge
Total Battery Capacity (Wh) =
16420×1
0.9×0.95
= 19204.67Wh
Since we are using a 15kWh lithium battery
The No. of Batteries is given by
TotalBatteryCapacity
BatteryCapacity
=
19204.67
15000
= 1.28 ≈2battery is ideal for this installation.
II.Backup Hours of Batteries
Since the number of batteries is known, to calculate the Backup Time for these given
battery, we use this formula to calculate the backup hours of batteries.
BatteryCapacity×No.ofBatteries
TotalBatteryCapacity=15000Wh×1battery=15000Wh
BackupHour=
TotalBatteryCapacity
Load
BackupHour=
15000
3265
=4.59Hours
3.4.5Photovoltaic System Specification
The photovoltaic (PV) system forms the backbone of the renewable energy supply for this
project. The design employs eight monocrystalline solar modules of two close ratings: four
panels are rated at 545 W with a nominal voltage of 40.8 V and current of 13.36 A, while the
32
95% Depth of Discharge.
Therefore;
Total Battery Capacity (Wh) =
DailyEnergy(Wh)×DaysofAutonomy
SystemEfficiency×DepthofDischarge
Total Battery Capacity (Wh) =
16420×1
0.9×0.95
= 19204.67Wh
Since we are using a 15kWh lithium battery
The No. of Batteries is given by
TotalBatteryCapacity
BatteryCapacity
=
19204.67
15000
= 1.28 ≈2battery is ideal for this installation.
II.Backup Hours of Batteries
Since the number of batteries is known, to calculate the Backup Time for these given
battery, we use this formula to calculate the backup hours of batteries.
BatteryCapacity×No.ofBatteries
TotalBatteryCapacity=15000Wh×1battery=15000Wh
BackupHour=
TotalBatteryCapacity
Load
BackupHour=
15000
3265
=4.59Hours
3.4.5Photovoltaic System Specification
The photovoltaic (PV) system forms the backbone of the renewable energy supply for this
project. The design employs eight monocrystalline solar modules of two close ratings: four
panels are rated at 545 W with a nominal voltage of 40.8 V and current of 13.36 A, while the
32
other four are rated at 550 W with a nominal voltage of 41.58 V and current of 13.23 A. To
optimize the configuration, one 545 W panel and one 550 W panel are connected in series,
forming a string with a combined voltage of approximately 82.38 V and a current determined by
the lower-rated panel, about 13.23 A. This arrangement is repeated for the four pairs of panels,
resulting in four identical series strings. These strings are then connected in parallel, increasing
the total array current to about 52.92 A (4 × 13.23 A) while maintaining the operating voltage of
approximately 82.38 V. The combined peak power of the PV array is 4.38 kW (4 × (545 W +
550 W)), which is sufficient to meet the load demand and charge the 51.2 V lithium-ion battery
bank through the MPPT charge controller during peak sun hours. This hybrid series-parallel
configuration ensures both voltage compatibility with the battery system and sufficient current
for reliable operation. The modules are installed at an optimal tilt and orientation to maximize
energy harvest.
3.4.6Charge Controller Specification
Charge controllers limit the rate at which electric current is added or drawn from batteries. It
prevents overcharging and may also prevent completely draining (deep discharging) a battery to
protect battery life. Estimating an appropriate charge controller begins by calculating the
required total current that the controller ought to withstand. From the outcome of the required
current, the total number of charge controllers would then be able to be figured and once the cost
of a single charge controller is known, the total cost of the controllers would then be able to be
resolved [21].
I.Required Charge Controller Current; I
rcc
Open Circuit Voltage V
oc
of550Wpanel=50.27V
Open Circuit Voltage V
oc
of545Wpanel=49.52V
Total Open Circuit Voltage of PV panels V
oc
=50.27+49.52=99.79
A charge controller of 60-130VDC open circuit PV voltage array range and 80A was used for
this installation
33
optimize the configuration, one 545 W panel and one 550 W panel are connected in series,
forming a string with a combined voltage of approximately 82.38 V and a current determined by
the lower-rated panel, about 13.23 A. This arrangement is repeated for the four pairs of panels,
resulting in four identical series strings. These strings are then connected in parallel, increasing
the total array current to about 52.92 A (4 × 13.23 A) while maintaining the operating voltage of
approximately 82.38 V. The combined peak power of the PV array is 4.38 kW (4 × (545 W +
550 W)), which is sufficient to meet the load demand and charge the 51.2 V lithium-ion battery
bank through the MPPT charge controller during peak sun hours. This hybrid series-parallel
configuration ensures both voltage compatibility with the battery system and sufficient current
for reliable operation. The modules are installed at an optimal tilt and orientation to maximize
energy harvest.
3.4.6Charge Controller Specification
Charge controllers limit the rate at which electric current is added or drawn from batteries. It
prevents overcharging and may also prevent completely draining (deep discharging) a battery to
protect battery life. Estimating an appropriate charge controller begins by calculating the
required total current that the controller ought to withstand. From the outcome of the required
current, the total number of charge controllers would then be able to be figured and once the cost
of a single charge controller is known, the total cost of the controllers would then be able to be
resolved [21].
I.Required Charge Controller Current; I
rcc
Open Circuit Voltage V
oc
of550Wpanel=50.27V
Open Circuit Voltage V
oc
of545Wpanel=49.52V
Total Open Circuit Voltage of PV panels V
oc
=50.27+49.52=99.79
A charge controller of 60-130VDC open circuit PV voltage array range and 80A was used for
this installation
33
3.4.7Cable Sizing
The design of a solar system is partial until the point when the right size and type of cable is
chosen for wiring the components together. The follow cable interfaces in the PV system must be
suitably chosen:
The dc cable from the PV array to the battery bank through the charge controller.
The ac cable from the inverter to the distribution board (DB) of the residence.
I.PV Array to Battery Bank Through Charge Controller; I
CAB
I
CAB
=I
SC
×N
P
×F
safe
I
rcc
=13.75×8×1.25=132.3A
10mm
2
isusedforthisapplication
II.Inverter To Distribution Board; I
oi
I
oi
=
P
I
V
oi×PF
Where; V
oi
=outputvoltageoftheinverter
I
oi=
4081.25
220×0.8
=23.19A
A6mm
2
cableissuitableforthisapplication .
34
The design of a solar system is partial until the point when the right size and type of cable is
chosen for wiring the components together. The follow cable interfaces in the PV system must be
suitably chosen:
The dc cable from the PV array to the battery bank through the charge controller.
The ac cable from the inverter to the distribution board (DB) of the residence.
I.PV Array to Battery Bank Through Charge Controller; I
CAB
I
CAB
=I
SC
×N
P
×F
safe
I
rcc
=13.75×8×1.25=132.3A
10mm
2
isusedforthisapplication
II.Inverter To Distribution Board; I
oi
I
oi
=
P
I
V
oi×PF
Where; V
oi
=outputvoltageoftheinverter
I
oi=
4081.25
220×0.8
=23.19A
A6mm
2
cableissuitableforthisapplication .
34
CHAPTER FOUR
RESULTS, TESTING AND PERFORMANCE EVALUATION
4.1 Introduction
This chapter presents the results of designing and implementing a 1 kVA inverter and installing a
10kVA solar power system at the University of Jos. While Chapter Three explained
methodology and design, this chapter demonstrates practical realization and testing. It bridges
theoretical assumptions with real-life performance, showing where the systems met or deviated
from expectations.
The results cover both quantitative test efficiency, load handling, and waveform quality and
qualitative aspects such as durability and ease of installation. The first section discusses the 1
kVA inverter prototype, including oscillator operation, driver performance, MOSFET switching,
and transformer response. Tests measured voltage, current, power output, thermal behaviour, and
overload protection under varying loads. The second section details the 10kVA solar system with
15kWh lithium battery, a 10 kVA inverter, solar panels, charge controller, breakers, and wiring
across the department. Finally, diagrams and photographs illustrate how design theory was
translated into functional systems meeting departmental energy needs
4.2 Results and Testing of the 1 kVA Inverter
The construction of the 1 kVA inverter marked the first stage of practical implementation in this
project. The design, which was earlier modelled in Proteus software, was transferred into
physical reality by assembling the oscillator, driver, MOSFET switching stage, and transformer.
For the oscillator stage, a CD4069 IC was used to generate square wave pulses, which were then
fed into optocouplers and transistor buffers before driving the MOSFETs. The driver section
amplified the signals sufficiently for gate switching, while twelve IRFP150N MOSFETs
connected in parallel provided the current-handling capability required for a 1 kVA load. The
power section, consisting of a custom-wound transformer, stepped up the 24 V DC input from
batteries to 220 V AC. During construction, extra care was taken to ensure isolation between the
35
RESULTS, TESTING AND PERFORMANCE EVALUATION
4.1 Introduction
This chapter presents the results of designing and implementing a 1 kVA inverter and installing a
10kVA solar power system at the University of Jos. While Chapter Three explained
methodology and design, this chapter demonstrates practical realization and testing. It bridges
theoretical assumptions with real-life performance, showing where the systems met or deviated
from expectations.
The results cover both quantitative test efficiency, load handling, and waveform quality and
qualitative aspects such as durability and ease of installation. The first section discusses the 1
kVA inverter prototype, including oscillator operation, driver performance, MOSFET switching,
and transformer response. Tests measured voltage, current, power output, thermal behaviour, and
overload protection under varying loads. The second section details the 10kVA solar system with
15kWh lithium battery, a 10 kVA inverter, solar panels, charge controller, breakers, and wiring
across the department. Finally, diagrams and photographs illustrate how design theory was
translated into functional systems meeting departmental energy needs
4.2 Results and Testing of the 1 kVA Inverter
The construction of the 1 kVA inverter marked the first stage of practical implementation in this
project. The design, which was earlier modelled in Proteus software, was transferred into
physical reality by assembling the oscillator, driver, MOSFET switching stage, and transformer.
For the oscillator stage, a CD4069 IC was used to generate square wave pulses, which were then
fed into optocouplers and transistor buffers before driving the MOSFETs. The driver section
amplified the signals sufficiently for gate switching, while twelve IRFP150N MOSFETs
connected in parallel provided the current-handling capability required for a 1 kVA load. The
power section, consisting of a custom-wound transformer, stepped up the 24 V DC input from
batteries to 220 V AC. During construction, extra care was taken to ensure isolation between the
35
control and power sections so as to minimise interference and improve stability. Once all the
components were soldered onto a Vero board and mounted on heat sinks where necessary, the
circuit was encased in a metallic frame for protection.
Figure: 4.1: Constructed 1 kVA Inverter.
Testing of the inverter was carried out in stages to confirm proper functioning before full load
evaluation. At the oscillator stage, the output was connected to an oscilloscope to verify the
generation of square wave signals at a frequency close to 50 Hz. The waveform obtained
matched expectations, with slight distortions attributed to switching delays. This confirmed that
the CD4069 IC was oscillating correctly. Next, the driver stage was tested by probing the gate
inputs of the MOSFETs, where a signal amplitude of about 12 V peak was observed. This was
sufficient for driving the MOSFETs into saturation. At the power switching stage, the
transformer primary was connected, and alternating current was observed across the winding
terminals, indicating proper switching operation. Finally, at the output stage, measurements were
taken across the transformer secondary, where a steady AC voltage of about 220 V was recorded.
This confirmed that the inverter was producing the required mains-level voltage suitable for
domestic appliances.
After confirming the correct operation of the various stages, load tests were conducted using
resistive loads such as electric bulbs, fans, heaters, and small appliances. At no load, the output
36
components were soldered onto a Vero board and mounted on heat sinks where necessary, the
circuit was encased in a metallic frame for protection.
Figure: 4.1: Constructed 1 kVA Inverter.
Testing of the inverter was carried out in stages to confirm proper functioning before full load
evaluation. At the oscillator stage, the output was connected to an oscilloscope to verify the
generation of square wave signals at a frequency close to 50 Hz. The waveform obtained
matched expectations, with slight distortions attributed to switching delays. This confirmed that
the CD4069 IC was oscillating correctly. Next, the driver stage was tested by probing the gate
inputs of the MOSFETs, where a signal amplitude of about 12 V peak was observed. This was
sufficient for driving the MOSFETs into saturation. At the power switching stage, the
transformer primary was connected, and alternating current was observed across the winding
terminals, indicating proper switching operation. Finally, at the output stage, measurements were
taken across the transformer secondary, where a steady AC voltage of about 220 V was recorded.
This confirmed that the inverter was producing the required mains-level voltage suitable for
domestic appliances.
After confirming the correct operation of the various stages, load tests were conducted using
resistive loads such as electric bulbs, fans, heaters, and small appliances. At no load, the output
36
voltage was close to 220 V. With a 100 W bulb connected, the voltage remained stable at 219 V,
and the bulb operated without visible flickering. When a 300 W fan was tested, the voltage
dropped slightly to around 218 V, but the fan operated smoothly with no humming sound. A 500
W electric heater was then connected, and the inverter supplied the load efficiently, with the
transformer warming slightly but remaining within safe temperature limits. Finally, the inverter
was tested with a 1000 W pressing iron, which brought the system close to full capacity. The
output voltage dropped marginally to 214 V, but the appliance worked satisfactorily. An attempt
to exceed the rated capacity by connecting a 1300 W combination of iron and fan triggered the
overload protection system, cutting off the supply and preventing damage to the MOSFETs or
transformer. These observations demonstrate that the inverter was able to supply up to its rated
capacity reliably, with built-in protection mechanisms functioning as designed.
Efficiency measurements were also conducted during the load tests. The DC input power was
determined by multiplying the battery voltage (24 V) by the input current drawn, while the AC
output power was measured based on load ratings and current at the secondary side. For instance,
at full load, the input power was measured at approximately 1176 W (24 V × 49 A), while the
output delivered was about 1000 W, giving an efficiency of around 85%. This level of efficiency
aligns with expectations for square wave inverters of this category, which typically fall between
80% and 90%. Oscilloscope observations confirmed that the inverter produced a square wave
output at a frequency of ~50 Hz. While this waveform is suitable for lighting and heating loads,
it is not recommended for sensitive electronic devices such as computers or medical instruments,
which require pure sine wave inverters.
Figure 4.2: Output Waveform of the 1 kVA Inverter presents the observed square wave
during testing.
37
and the bulb operated without visible flickering. When a 300 W fan was tested, the voltage
dropped slightly to around 218 V, but the fan operated smoothly with no humming sound. A 500
W electric heater was then connected, and the inverter supplied the load efficiently, with the
transformer warming slightly but remaining within safe temperature limits. Finally, the inverter
was tested with a 1000 W pressing iron, which brought the system close to full capacity. The
output voltage dropped marginally to 214 V, but the appliance worked satisfactorily. An attempt
to exceed the rated capacity by connecting a 1300 W combination of iron and fan triggered the
overload protection system, cutting off the supply and preventing damage to the MOSFETs or
transformer. These observations demonstrate that the inverter was able to supply up to its rated
capacity reliably, with built-in protection mechanisms functioning as designed.
Efficiency measurements were also conducted during the load tests. The DC input power was
determined by multiplying the battery voltage (24 V) by the input current drawn, while the AC
output power was measured based on load ratings and current at the secondary side. For instance,
at full load, the input power was measured at approximately 1176 W (24 V × 49 A), while the
output delivered was about 1000 W, giving an efficiency of around 85%. This level of efficiency
aligns with expectations for square wave inverters of this category, which typically fall between
80% and 90%. Oscilloscope observations confirmed that the inverter produced a square wave
output at a frequency of ~50 Hz. While this waveform is suitable for lighting and heating loads,
it is not recommended for sensitive electronic devices such as computers or medical instruments,
which require pure sine wave inverters.
Figure 4.2: Output Waveform of the 1 kVA Inverter presents the observed square wave
during testing.
37
Overall, the results from the 1 kVA inverter prototype demonstrate that the design objectives
were achieved. The inverter successfully converted 24 V DC into 220 V AC at 50 Hz, supplied
various resistive loads up to 1 kVA, and provided overload protection when capacity was
exceeded. Although the efficiency was slightly below that of commercial sine wave inverters, the
prototype performed reliably within its intended scope, validating the design methodology
presented in Chapter Three. These results also provided valuable insights into component
behaviour, thermal management, and protection schemes, which became useful when scaling the
project towards larger installations such as the 10kVA solar system implemented at the
Department.
No-load voltage
S/NImput Voltage
(DC)
Output Voltage
(AC)
Power (p=IV)Current
1 24V 215V 1KVA 4.65A
On-load voltages
AppliancesTypical P(W)AC VoltageAC currentsDC CurrentsDescription
LED Bulb 15 214.78V0.69 0.694A Negligible
droop
CFL Bulb 20 214.70V 0.93 0.926A Small Load
Phone
charger
10 214.85V 0.46 0.463A Tiny Load
Laptop
Charger
65 214.10 0.28 2.778A Steady
Moderate
load
Printer 100 213.50 0.47 4.630A Short Burst
while
printing
38
were achieved. The inverter successfully converted 24 V DC into 220 V AC at 50 Hz, supplied
various resistive loads up to 1 kVA, and provided overload protection when capacity was
exceeded. Although the efficiency was slightly below that of commercial sine wave inverters, the
prototype performed reliably within its intended scope, validating the design methodology
presented in Chapter Three. These results also provided valuable insights into component
behaviour, thermal management, and protection schemes, which became useful when scaling the
project towards larger installations such as the 10kVA solar system implemented at the
Department.
No-load voltage
S/NImput Voltage
(DC)
Output Voltage
(AC)
Power (p=IV)Current
1 24V 215V 1KVA 4.65A
On-load voltages
AppliancesTypical P(W)AC VoltageAC currentsDC CurrentsDescription
LED Bulb 15 214.78V0.69 0.694A Negligible
droop
CFL Bulb 20 214.70V 0.93 0.926A Small Load
Phone
charger
10 214.85V 0.46 0.463A Tiny Load
Laptop
Charger
65 214.10 0.28 2.778A Steady
Moderate
load
Printer 100 213.50 0.47 4.630A Short Burst
while
printing
38
4.3 Discussion and Evaluation of the 1 kVA Inverter Prototype
The results obtained from the testing of the 1 kVA inverter prototype provide a practical
foundation for discussing both the strengths and weaknesses of the system. One of the most
striking outcomes was the ability of the inverter to deliver stable AC voltage across a range of
domestic loads, including bulbs, fans, heaters, and pressing irons. The output remained close to
220 V in most cases, with only a minor drop observed at full load. This stability indicates that the
transformer design, MOSFET configuration, and driver circuit worked in harmony to maintain
voltage regulation under different conditions. The efficiency recorded, at about 85%, is
considered satisfactory for a square-wave inverter. When compared with similar low-cost
inverters in the Nigerian market, which usually operate between 75% and 90% efficiency, the
prototype falls within a competitive range. The successful functioning of the overload protection
further strengthens confidence in the design, because it prevented damage when the system was
pushed beyond its 1 kVA rating. Such protection is especially important in Nigerian households
and institutions where users often overload power equipment unintentionally.
Despite these achievements, there are limitations worth highlighting. The square-wave output
observed on the oscilloscope, while acceptable for resistive loads, is not suitable for sensitive
electronics such as laptops, desktop computers, or laboratory instruments that require pure sine
wave input. Square-wave inverters are also less efficient when dealing with inductive loads like
refrigerators or air conditioners, since the waveform causes additional losses in motors and can
lead to humming noise. This limitation explains why many commercial inverters today rely on
pulse-width modulation (PWM) techniques to generate modified or pure sine waves. The
prototype, however, was deliberately designed as a square-wave inverter in order to simplify
construction, minimize cost, and highlight the basic principles of inverter operation. Future
improvements could include upgrading the control section to a PWM-based microcontroller
system that can approximate or generate pure sine wave outputs. This would make the inverter
more versatile and suitable for a wider range of applications within the Nigerian context.
Another critical issue is thermal performance. Although the MOSFETs were mounted on heat
sinks and supplemented with fan cooling, slight heating was still observed at high loads. The
calculated junction temperature without heat sinks exceeded safe limits, making the use of proper
39
The results obtained from the testing of the 1 kVA inverter prototype provide a practical
foundation for discussing both the strengths and weaknesses of the system. One of the most
striking outcomes was the ability of the inverter to deliver stable AC voltage across a range of
domestic loads, including bulbs, fans, heaters, and pressing irons. The output remained close to
220 V in most cases, with only a minor drop observed at full load. This stability indicates that the
transformer design, MOSFET configuration, and driver circuit worked in harmony to maintain
voltage regulation under different conditions. The efficiency recorded, at about 85%, is
considered satisfactory for a square-wave inverter. When compared with similar low-cost
inverters in the Nigerian market, which usually operate between 75% and 90% efficiency, the
prototype falls within a competitive range. The successful functioning of the overload protection
further strengthens confidence in the design, because it prevented damage when the system was
pushed beyond its 1 kVA rating. Such protection is especially important in Nigerian households
and institutions where users often overload power equipment unintentionally.
Despite these achievements, there are limitations worth highlighting. The square-wave output
observed on the oscilloscope, while acceptable for resistive loads, is not suitable for sensitive
electronics such as laptops, desktop computers, or laboratory instruments that require pure sine
wave input. Square-wave inverters are also less efficient when dealing with inductive loads like
refrigerators or air conditioners, since the waveform causes additional losses in motors and can
lead to humming noise. This limitation explains why many commercial inverters today rely on
pulse-width modulation (PWM) techniques to generate modified or pure sine waves. The
prototype, however, was deliberately designed as a square-wave inverter in order to simplify
construction, minimize cost, and highlight the basic principles of inverter operation. Future
improvements could include upgrading the control section to a PWM-based microcontroller
system that can approximate or generate pure sine wave outputs. This would make the inverter
more versatile and suitable for a wider range of applications within the Nigerian context.
Another critical issue is thermal performance. Although the MOSFETs were mounted on heat
sinks and supplemented with fan cooling, slight heating was still observed at high loads. The
calculated junction temperature without heat sinks exceeded safe limits, making the use of proper
39
cooling systems a necessity rather than an option. This observation reflects real-life challenges in
power electronics, where thermal runaway can shorten the lifespan of components if not
managed adequately. The transformer also produced an audible humming noise under heavy
load, which is a common feature of square-wave inverters but may not be acceptable in
environments that require quiet operation, such as lecture halls or laboratories. These
shortcomings are not failures of design but rather natural consequences of using simple, low-cost
methods to achieve the set objectives. They provide lessons on the importance of considering
user environment, component ratings, and long-term reliability when designing larger systems.
In summary, the 1 kVA inverter prototype can be considered a success within its intended scope.
It achieved the fundamental aim of converting DC power into usable AC power at mains voltage,
supplied different loads up to its rated capacity, and provided protection against overload. The
efficiency was within acceptable limits, and the overall construction confirmed the viability of
the design presented in Chapter Three. At the same time, the limitations observed, especially in
waveform quality and thermal management, point towards opportunities for future improvement.
These insights were not merely academic but became practically useful when scaling up to the
design and installation of the 10 kVA solar system in the Department of Electrical and
Electronics Engineering. Lessons from the prototype’s testing guided the choice of inverter type,
cabling, protection devices, and cooling considerations in the larger system, ensuring that the
departmental installation avoided common pitfalls of small-scale designs.
4.4 Results of the 10 kVA Solar System Installation
The installation of the 10kVA solar power system in the Department of Electrical and
Electronics Engineering, University of Jos, produced results that demonstrate the practicality of
renewable energy deployment in academic environments. From the onset, the focus was on
ensuring that both the power conversion system and the wiring infrastructure were robust enough
to support continuous operation of offices, classrooms, and laboratories within the department.
The system was composed of a 10 kVA Felicity inverter (non-hybrid), a lithium battery bank, a
80 A charge controller, and eight photovoltaic modules comprising four 550 W panels and four
545 W panels. To maximize performance, each 550 W module was paired in series with a 545 W
module, and the pairs were then connected in parallel to form the final array. This approach was
40
power electronics, where thermal runaway can shorten the lifespan of components if not
managed adequately. The transformer also produced an audible humming noise under heavy
load, which is a common feature of square-wave inverters but may not be acceptable in
environments that require quiet operation, such as lecture halls or laboratories. These
shortcomings are not failures of design but rather natural consequences of using simple, low-cost
methods to achieve the set objectives. They provide lessons on the importance of considering
user environment, component ratings, and long-term reliability when designing larger systems.
In summary, the 1 kVA inverter prototype can be considered a success within its intended scope.
It achieved the fundamental aim of converting DC power into usable AC power at mains voltage,
supplied different loads up to its rated capacity, and provided protection against overload. The
efficiency was within acceptable limits, and the overall construction confirmed the viability of
the design presented in Chapter Three. At the same time, the limitations observed, especially in
waveform quality and thermal management, point towards opportunities for future improvement.
These insights were not merely academic but became practically useful when scaling up to the
design and installation of the 10 kVA solar system in the Department of Electrical and
Electronics Engineering. Lessons from the prototype’s testing guided the choice of inverter type,
cabling, protection devices, and cooling considerations in the larger system, ensuring that the
departmental installation avoided common pitfalls of small-scale designs.
4.4 Results of the 10 kVA Solar System Installation
The installation of the 10kVA solar power system in the Department of Electrical and
Electronics Engineering, University of Jos, produced results that demonstrate the practicality of
renewable energy deployment in academic environments. From the onset, the focus was on
ensuring that both the power conversion system and the wiring infrastructure were robust enough
to support continuous operation of offices, classrooms, and laboratories within the department.
The system was composed of a 10 kVA Felicity inverter (non-hybrid), a lithium battery bank, a
80 A charge controller, and eight photovoltaic modules comprising four 550 W panels and four
545 W panels. To maximize performance, each 550 W module was paired in series with a 545 W
module, and the pairs were then connected in parallel to form the final array. This approach was
40
deliberate because it ensured that voltage output remained consistent while current capacity was
increased, thus preventing imbalance or mismatch losses. The result of this arrangement was a
photovoltaic array capable of delivering stable current to the charge controller, which in turn
supplied both the lithium battery bank and the inverter with reliable DC input.
Figure 4.4: Connection of Solar Panels in Series-Parallel Arrangement shows the
arrangement clearly.
During the wiring phase, careful attention was paid to current-carrying capacity and voltage
drop, since the distances between the rooftop solar panels, the charge controller, and the inverter
room were considerable. A 10 mm² DC cable of approximately 25 meters was used to connect
the solar panels to the charge controller, ensuring that line losses were minimized and safety
standards upheld. On the AC side, a 10 mm² cable of 60 meters was used to run power from the
distribution board (DB) to the inverter and subsequently to all connected laboratory and office
loads. This thickness was chosen because the expected currents on the AC side were relatively
higher, and thinner cables would have caused overheating or voltage drop problems. For internal
distribution, 2.5 mm² cables were used for sockets while 1.5 mm² cables were allocated to
lighting points. These choices reflected Nigerian wiring practices and guaranteed that each
circuit was both safe and adequate for its intended load. In terms of results, the socket points
functioned well during tests, powering laptops, desktop computers, and laboratory trainers
without tripping the breakers. Similarly, the lighting points operated with the installed 10 W
energy-saving lamps, delivering bright and stable illumination across classrooms and offices.
41
increased, thus preventing imbalance or mismatch losses. The result of this arrangement was a
photovoltaic array capable of delivering stable current to the charge controller, which in turn
supplied both the lithium battery bank and the inverter with reliable DC input.
Figure 4.4: Connection of Solar Panels in Series-Parallel Arrangement shows the
arrangement clearly.
During the wiring phase, careful attention was paid to current-carrying capacity and voltage
drop, since the distances between the rooftop solar panels, the charge controller, and the inverter
room were considerable. A 10 mm² DC cable of approximately 25 meters was used to connect
the solar panels to the charge controller, ensuring that line losses were minimized and safety
standards upheld. On the AC side, a 10 mm² cable of 60 meters was used to run power from the
distribution board (DB) to the inverter and subsequently to all connected laboratory and office
loads. This thickness was chosen because the expected currents on the AC side were relatively
higher, and thinner cables would have caused overheating or voltage drop problems. For internal
distribution, 2.5 mm² cables were used for sockets while 1.5 mm² cables were allocated to
lighting points. These choices reflected Nigerian wiring practices and guaranteed that each
circuit was both safe and adequate for its intended load. In terms of results, the socket points
functioned well during tests, powering laptops, desktop computers, and laboratory trainers
without tripping the breakers. Similarly, the lighting points operated with the installed 10 W
energy-saving lamps, delivering bright and stable illumination across classrooms and offices.
41
Figure 4.5: Distribution Board Wiring and Protection Layout illustrates the arrangement.
An equally important result was the performance of the protective devices. Three 10 A circuit
breakers were distributed across offices and laboratories, while an additional 6 A circuit breaker
was dedicated to projectors in the 300-level, 400-level, and 500-level classrooms. These breakers
were tested during trial runs by applying intentional overloads, and they responded correctly by
disconnecting the affected circuits without disturbing the rest of the installation. This selective
coordination ensured that minor faults or overloads in one section did not cause a blackout across
the entire department. It also emphasized the importance of installing the right protection at the
right point, since a single breaker could not have provided the level of granularity needed for an
academic facility with diverse load types. The result was a system that not only worked
effectively but also provided confidence in terms of safety and reliability. Another notable
observation was the synergy between the solar panels, charge controller, and lithium battery
bank. The batteries, with their higher depth of discharge and faster charging capability,
maintained stable output during evening operations when sunlight was no longer available. In
practice, this meant that classes and laboratory sessions held after daylight hours continued
without interruption, a sharp contrast to the frequent outages that occur when relying solely on
grid supply. Testing indicated that the system was able to sustain essential loads for over six
hours after sunset, proving that the combination of panel arrangement, battery sizing, and
inverter capacity was well matched to the department’s requirements. Furthermore, the 10 kVA
inverter delivered clean AC output that successfully powered sensitive electronics like projectors
and computers, unlike the 1 kVA prototype discussed earlier, which was limited to resistive
loads. This difference highlighted the benefit of investing in higher-grade equipment for
institutional applications.
42
An equally important result was the performance of the protective devices. Three 10 A circuit
breakers were distributed across offices and laboratories, while an additional 6 A circuit breaker
was dedicated to projectors in the 300-level, 400-level, and 500-level classrooms. These breakers
were tested during trial runs by applying intentional overloads, and they responded correctly by
disconnecting the affected circuits without disturbing the rest of the installation. This selective
coordination ensured that minor faults or overloads in one section did not cause a blackout across
the entire department. It also emphasized the importance of installing the right protection at the
right point, since a single breaker could not have provided the level of granularity needed for an
academic facility with diverse load types. The result was a system that not only worked
effectively but also provided confidence in terms of safety and reliability. Another notable
observation was the synergy between the solar panels, charge controller, and lithium battery
bank. The batteries, with their higher depth of discharge and faster charging capability,
maintained stable output during evening operations when sunlight was no longer available. In
practice, this meant that classes and laboratory sessions held after daylight hours continued
without interruption, a sharp contrast to the frequent outages that occur when relying solely on
grid supply. Testing indicated that the system was able to sustain essential loads for over six
hours after sunset, proving that the combination of panel arrangement, battery sizing, and
inverter capacity was well matched to the department’s requirements. Furthermore, the 10 kVA
inverter delivered clean AC output that successfully powered sensitive electronics like projectors
and computers, unlike the 1 kVA prototype discussed earlier, which was limited to resistive
loads. This difference highlighted the benefit of investing in higher-grade equipment for
institutional applications.
42
Figure 4.7: Inverter and Lithium Battery Bank Setup illustrates this section of the
installation.
4.5 Discussion and Evaluation of the 10kVA Solar System Installation
The installation of the 10 kVA solar system at the Department of Electrical and Electronics
Engineering, University of Jos, provided a unique opportunity to evaluate the performance of a
medium-scale renewable energy project within a Nigerian academic environment. The
discussion begins with the panel arrangement, which was a crucial decision in balancing voltage
and current outputs. By connecting each 550 W panel in series with a 545 W panel and then
combining the pairs in parallel, the design ensured stable operation despite slight differences in
the manufacturer ratings of the panels. This was important because solar panels, when
mismatched, often suffer from output reductions due to current limitations from the weakest
panel. However, in this setup, the parallel arrangement helped to equalize performance, thereby
delivering a reliable output to the charge controller. During testing, the panels performed well
under peak sun conditions, producing sufficient current to both charge the lithium batteries and
power loads simultaneously. Even during cloudy hours, the system maintained a steady supply,
although output was naturally reduced. This proved that the panel arrangement strategy was
effective and that Nigerian universities can confidently adopt similar setups.
43
installation.
4.5 Discussion and Evaluation of the 10kVA Solar System Installation
The installation of the 10 kVA solar system at the Department of Electrical and Electronics
Engineering, University of Jos, provided a unique opportunity to evaluate the performance of a
medium-scale renewable energy project within a Nigerian academic environment. The
discussion begins with the panel arrangement, which was a crucial decision in balancing voltage
and current outputs. By connecting each 550 W panel in series with a 545 W panel and then
combining the pairs in parallel, the design ensured stable operation despite slight differences in
the manufacturer ratings of the panels. This was important because solar panels, when
mismatched, often suffer from output reductions due to current limitations from the weakest
panel. However, in this setup, the parallel arrangement helped to equalize performance, thereby
delivering a reliable output to the charge controller. During testing, the panels performed well
under peak sun conditions, producing sufficient current to both charge the lithium batteries and
power loads simultaneously. Even during cloudy hours, the system maintained a steady supply,
although output was naturally reduced. This proved that the panel arrangement strategy was
effective and that Nigerian universities can confidently adopt similar setups.
43
ConditionAC
Power(W)
AC Current
(A)
DC Current
from Battery
PV (Voltage)PV (Current)
No-load 0 0 1.54A 85V 0.96A
Voltage and Current Output of Series-Parallel Panel Connection under Load illustrates this
finding.
Another major aspect of evaluation was the performance of the charge controller and inverter.
The 80 A charge controller operated efficiently, preventing both overcharging and deep
discharge of the lithium batteries. Its function was particularly important in ensuring that the
expensive battery bank did not deteriorate prematurely, as uncontrolled charging is one of the
main causes of reduced battery lifespan in PV systems. The 10 kVA Felicity inverter delivered a
consistent 220 V AC output, which was stable even under varying loads, including computers,
projectors, laboratory trainers, and lighting circuits. Unlike smaller square-wave inverters, this
inverter provided a near-sinusoidal output, meaning that sensitive electronics were protected
from voltage distortions. During prolonged use, the inverter maintained efficiency levels above
90%, which is acceptable for institutional power supply. Load testing further showed that
simultaneous use of multiple classrooms and offices was possible without tripping the system,
provided that the total load did not exceed the designed threshold. These results underline the
reliability of modern non-hybrid inverters in academic institutions, where steady and quality
supply is critical.
The protective devices installed in the system also performed their role satisfactorily,
highlighting the importance of safety in solar installations. The use of three 10A circuit breakers
across offices and laboratories, and a dedicated 6 A breaker for classroom projectors, provided
selective coordination. This meant that if a fault occurred in one part of the system, only the
affected breaker tripped, leaving the rest of the facility powered. For example, during a simulated
fault on one laboratory socket, only the breaker for that section tripped, while other offices and
classrooms continued operating normally. This not only demonstrated proper protection design
but also reduced the likelihood of total blackout in the department. Furthermore, the chosen cable
sizes (2.5 mm² for sockets, 1.5 mm² for lighting, 10 mm² DC for panel-controller connections,
and 10 mm² AC for inverter-distribution board runs) ensured that overheating, voltage drop, and
44
Power(W)
AC Current
(A)
DC Current
from Battery
PV (Voltage)PV (Current)
No-load 0 0 1.54A 85V 0.96A
Voltage and Current Output of Series-Parallel Panel Connection under Load illustrates this
finding.
Another major aspect of evaluation was the performance of the charge controller and inverter.
The 80 A charge controller operated efficiently, preventing both overcharging and deep
discharge of the lithium batteries. Its function was particularly important in ensuring that the
expensive battery bank did not deteriorate prematurely, as uncontrolled charging is one of the
main causes of reduced battery lifespan in PV systems. The 10 kVA Felicity inverter delivered a
consistent 220 V AC output, which was stable even under varying loads, including computers,
projectors, laboratory trainers, and lighting circuits. Unlike smaller square-wave inverters, this
inverter provided a near-sinusoidal output, meaning that sensitive electronics were protected
from voltage distortions. During prolonged use, the inverter maintained efficiency levels above
90%, which is acceptable for institutional power supply. Load testing further showed that
simultaneous use of multiple classrooms and offices was possible without tripping the system,
provided that the total load did not exceed the designed threshold. These results underline the
reliability of modern non-hybrid inverters in academic institutions, where steady and quality
supply is critical.
The protective devices installed in the system also performed their role satisfactorily,
highlighting the importance of safety in solar installations. The use of three 10A circuit breakers
across offices and laboratories, and a dedicated 6 A breaker for classroom projectors, provided
selective coordination. This meant that if a fault occurred in one part of the system, only the
affected breaker tripped, leaving the rest of the facility powered. For example, during a simulated
fault on one laboratory socket, only the breaker for that section tripped, while other offices and
classrooms continued operating normally. This not only demonstrated proper protection design
but also reduced the likelihood of total blackout in the department. Furthermore, the chosen cable
sizes (2.5 mm² for sockets, 1.5 mm² for lighting, 10 mm² DC for panel-controller connections,
and 10 mm² AC for inverter-distribution board runs) ensured that overheating, voltage drop, and
44
other wiring-related problems were avoided. The evaluation confirmed that the system adhered
to both Nigerian wiring practices and international safety standards.
Figure 4.10: Cable Sizing Arrangement in the Department captures this aspect.
Despite the overall success, a few challenges were observed during evaluation. The first was the
initial synchronization between the solar array and the charge controller, as fluctuating sunlight
during installation days caused delays in testing. Secondly, the long 60-meter AC cable run to
the distribution board meant that careful attention had to be given to connections to avoid energy
loss. Thirdly, the lithium batteries, while efficient, represented a significant financial investment,
raising questions of sustainability if such projects are to be replicated across multiple
departments. Additionally, though the system performed excellently during the dry season,
further long-term monitoring is required during the rainy season to evaluate performance under
prolonged low-sunlight conditions. These challenges do not diminish the success of the
installation but rather point to areas of future improvement, such as integrating hybrid inverters
with grid support or adding additional panels to provide more buffer during low sunlight.
In summary, the evaluation demonstrated that the 10kVA solar system was both technically
sound and practically beneficial. The department now enjoys stable electricity supply for
teaching and research, reduced reliance on erratic grid power, and improved safety due to well-
coordinated protection systems. The discussion therefore concludes that similar systems can be
scaled up in Nigerian universities and public institutions, provided that proper planning, quality
equipment, and skilled installation are applied.
45
to both Nigerian wiring practices and international safety standards.
Figure 4.10: Cable Sizing Arrangement in the Department captures this aspect.
Despite the overall success, a few challenges were observed during evaluation. The first was the
initial synchronization between the solar array and the charge controller, as fluctuating sunlight
during installation days caused delays in testing. Secondly, the long 60-meter AC cable run to
the distribution board meant that careful attention had to be given to connections to avoid energy
loss. Thirdly, the lithium batteries, while efficient, represented a significant financial investment,
raising questions of sustainability if such projects are to be replicated across multiple
departments. Additionally, though the system performed excellently during the dry season,
further long-term monitoring is required during the rainy season to evaluate performance under
prolonged low-sunlight conditions. These challenges do not diminish the success of the
installation but rather point to areas of future improvement, such as integrating hybrid inverters
with grid support or adding additional panels to provide more buffer during low sunlight.
In summary, the evaluation demonstrated that the 10kVA solar system was both technically
sound and practically beneficial. The department now enjoys stable electricity supply for
teaching and research, reduced reliance on erratic grid power, and improved safety due to well-
coordinated protection systems. The discussion therefore concludes that similar systems can be
scaled up in Nigerian universities and public institutions, provided that proper planning, quality
equipment, and skilled installation are applied.
45
4.6 Comparative Evaluation of the 1 kVA Inverter Prototype and the 10kVA Solar System
When comparing the 1 kVA inverter prototype with the 10kVA solar system installation, one
immediately notices the difference in scale and purpose. The 1 kVA inverter was constructed as
a proof of concept, focusing on how oscillators, MOSFET drivers, and transformers interact to
produce alternating current output from a direct current battery source. It was essentially a
teaching and learning model, designed to demonstrate the fundamentals of inverter design and
power electronics. In contrast, the 10kVA solar system was a full-scale deployment meant to
solve a real energy problem in the Department of Electrical and Electronics Engineering at the
University of Jos. While the 1 kVA inverter could power simple resistive loads such as bulbs and
fans, the 10kVA installation was capable of supporting complex departmental operations,
including projectors, laptops, laboratory trainers, and lighting across multiple offices and
classrooms. This difference in application reflects how theoretical designs can evolve into
practical solutions when scaled appropriately. Another area of comparison lies in performance
and efficiency. The 1 kVA inverter achieved an efficiency of about 85% under resistive load
conditions, which is acceptable for small-scale square wave inverters but insufficient for
sensitive electronics. Its square wave output limited the type of loads it could safely handle,
excluding devices such as computers and projectors which require a more stable sinusoidal
supply. On the other hand, the 10kVA Felicity inverter delivered efficiency levels above 90%
and provided a near-sinusoidal output, making it reliable for both resistive and inductive loads.
This meant that the solar system could sustain classroom and laboratory activities without fear of
equipment damage. Furthermore, the larger system included lithium batteries with a long
discharge cycle, allowing it to deliver stable energy for over six hours after sunset. The
prototype, however, had no such backup capability beyond its single battery source, making it
unsuitable for prolonged use. This contrast highlights how investment in higher capacity and
more advanced technology directly translates to reliability and functionality.
The final comparison is in terms of safety and sustainability. The 1 kVA prototype relied mainly
on simple design protections such as low-voltage alarms and a basic overload mechanism,
which, although effective at small scale, could not be trusted to protect against complex faults.
The 10kVA installation, however, integrated multiple circuit breakers of varying capacities,
proper cable sizing, and protective coordination that allowed faults to be isolated without
46
When comparing the 1 kVA inverter prototype with the 10kVA solar system installation, one
immediately notices the difference in scale and purpose. The 1 kVA inverter was constructed as
a proof of concept, focusing on how oscillators, MOSFET drivers, and transformers interact to
produce alternating current output from a direct current battery source. It was essentially a
teaching and learning model, designed to demonstrate the fundamentals of inverter design and
power electronics. In contrast, the 10kVA solar system was a full-scale deployment meant to
solve a real energy problem in the Department of Electrical and Electronics Engineering at the
University of Jos. While the 1 kVA inverter could power simple resistive loads such as bulbs and
fans, the 10kVA installation was capable of supporting complex departmental operations,
including projectors, laptops, laboratory trainers, and lighting across multiple offices and
classrooms. This difference in application reflects how theoretical designs can evolve into
practical solutions when scaled appropriately. Another area of comparison lies in performance
and efficiency. The 1 kVA inverter achieved an efficiency of about 85% under resistive load
conditions, which is acceptable for small-scale square wave inverters but insufficient for
sensitive electronics. Its square wave output limited the type of loads it could safely handle,
excluding devices such as computers and projectors which require a more stable sinusoidal
supply. On the other hand, the 10kVA Felicity inverter delivered efficiency levels above 90%
and provided a near-sinusoidal output, making it reliable for both resistive and inductive loads.
This meant that the solar system could sustain classroom and laboratory activities without fear of
equipment damage. Furthermore, the larger system included lithium batteries with a long
discharge cycle, allowing it to deliver stable energy for over six hours after sunset. The
prototype, however, had no such backup capability beyond its single battery source, making it
unsuitable for prolonged use. This contrast highlights how investment in higher capacity and
more advanced technology directly translates to reliability and functionality.
The final comparison is in terms of safety and sustainability. The 1 kVA prototype relied mainly
on simple design protections such as low-voltage alarms and a basic overload mechanism,
which, although effective at small scale, could not be trusted to protect against complex faults.
The 10kVA installation, however, integrated multiple circuit breakers of varying capacities,
proper cable sizing, and protective coordination that allowed faults to be isolated without
46
affecting the entire system. This level of protection was necessary to ensure safety in a
departmental environment where multiple users operate the system daily. In terms of
sustainability, the prototype was low-cost and educational but not designed for long-term
deployment. The solar system, though expensive due to lithium batteries and high-capacity
inverter, offered a practical long-term solution to the problem of unreliable grid power. It also
provided an environmentally friendly alternative to petrol or diesel generators, which are both
noisy and costly. The comparative evaluation therefore underscores the idea that while small
prototypes are vital for learning and testing design principles, scaling up with advanced
technologies is necessary for solving real-world problems.
Table 4.14: Comparative Safety and Sustainability Features of Both Systems captures this
contrast.
Feature 1 kVA Inverter System 10kVA Solar System
System Scale Small, typically for
households, offices, or single
appliances
Large, designed for commercial,
institutional, or mini-grid applications
Voltage / Current
Handling
Lower DC bus (≈24–48 V);
lower AC output (230 V, <5
A typical) → safer for
unskilled users
Higher DC bus (≈600–1000 V for PV
strings); AC output 3-phase, >60 A →
requires professional installation and
strict safety measures
Overload & Short-
Circuit Protection
Basic fuse or MCB protection;
simple resettable protection
against overload
Advanced protection: MCBs, MCCBs,
RCDs, SPD (Surge Protection
Devices), arc-fault detectors, and
remote monitoring for faults
Battery Safety Small sealed lead-acid or
lithium packs; lower thermal
runaway risk if managed
properly
Large battery banks (if hybrid/off-
grid) with high current draw; requires
advanced BMS, fire suppression,
ventilation
PV Array SafetyNot always connected directlyMultiple PV strings → DC isolators,
47
departmental environment where multiple users operate the system daily. In terms of
sustainability, the prototype was low-cost and educational but not designed for long-term
deployment. The solar system, though expensive due to lithium batteries and high-capacity
inverter, offered a practical long-term solution to the problem of unreliable grid power. It also
provided an environmentally friendly alternative to petrol or diesel generators, which are both
noisy and costly. The comparative evaluation therefore underscores the idea that while small
prototypes are vital for learning and testing design principles, scaling up with advanced
technologies is necessary for solving real-world problems.
Table 4.14: Comparative Safety and Sustainability Features of Both Systems captures this
contrast.
Feature 1 kVA Inverter System 10kVA Solar System
System Scale Small, typically for
households, offices, or single
appliances
Large, designed for commercial,
institutional, or mini-grid applications
Voltage / Current
Handling
Lower DC bus (≈24–48 V);
lower AC output (230 V, <5
A typical) → safer for
unskilled users
Higher DC bus (≈600–1000 V for PV
strings); AC output 3-phase, >60 A →
requires professional installation and
strict safety measures
Overload & Short-
Circuit Protection
Basic fuse or MCB protection;
simple resettable protection
against overload
Advanced protection: MCBs, MCCBs,
RCDs, SPD (Surge Protection
Devices), arc-fault detectors, and
remote monitoring for faults
Battery Safety Small sealed lead-acid or
lithium packs; lower thermal
runaway risk if managed
properly
Large battery banks (if hybrid/off-
grid) with high current draw; requires
advanced BMS, fire suppression,
ventilation
PV Array SafetyNot always connected directlyMultiple PV strings → DC isolators,
47
(can run only on
battery/utility)
string fuses, anti-islanding protection,
ground-fault monitoring required
Thermal
Management
Fan-cooled, small heat
dissipation (<100 W losses)
Forced air / liquid cooling; >1 kW
heat dissipation at high load; thermal
runaway prevention is critical
Maintenance
Needs
Minimal; occasional battery
check
Regular string inspection, cleaning of
PV panels, battery monitoring,
inverter firmware updates
Sustainability
Contribution
Provides backup power for
households; small carbon
offset if charged from PV
Major reduction in fossil fuel reliance;
can offset >20 tons of CO₂ per year
(for 15 kW @ ~5 h/day sun)
Lifecycle ImpactShorter lifespan (3–5 yrs for
lead batteries, 7–10 yrs
inverter)
Longer operational design (PV panels
20–25 yrs, inverter 10–15 yrs,
batteries 7–12 yrs if lithium)
End-of-Life
Considerations
Easier recycling; small-scale
e-waste
Large-scale recycling needed; PV
panel recycling emerging, lithium
recycling infrastructure required
Community
Impact
Individual energy resilience
(lights, phone charging, small
loads)
Grid support, rural electrification,
institutional backup (schools,
hospitals, industries)
Environmental
Risks
Minimal; mostly from small
batteries
Higher e-waste and fire hazard if not
properly managed; but much larger
renewable energy contribution
48
battery/utility)
string fuses, anti-islanding protection,
ground-fault monitoring required
Thermal
Management
Fan-cooled, small heat
dissipation (<100 W losses)
Forced air / liquid cooling; >1 kW
heat dissipation at high load; thermal
runaway prevention is critical
Maintenance
Needs
Minimal; occasional battery
check
Regular string inspection, cleaning of
PV panels, battery monitoring,
inverter firmware updates
Sustainability
Contribution
Provides backup power for
households; small carbon
offset if charged from PV
Major reduction in fossil fuel reliance;
can offset >20 tons of CO₂ per year
(for 15 kW @ ~5 h/day sun)
Lifecycle ImpactShorter lifespan (3–5 yrs for
lead batteries, 7–10 yrs
inverter)
Longer operational design (PV panels
20–25 yrs, inverter 10–15 yrs,
batteries 7–12 yrs if lithium)
End-of-Life
Considerations
Easier recycling; small-scale
e-waste
Large-scale recycling needed; PV
panel recycling emerging, lithium
recycling infrastructure required
Community
Impact
Individual energy resilience
(lights, phone charging, small
loads)
Grid support, rural electrification,
institutional backup (schools,
hospitals, industries)
Environmental
Risks
Minimal; mostly from small
batteries
Higher e-waste and fire hazard if not
properly managed; but much larger
renewable energy contribution
48
CHAPTER FIVE
SUMMARY AND CONCLUSION
5.1 Summary of the Work
This research project was initiated to address the persistent challenge of unreliable power supply
within the Department of Electrical and Electronics Engineering, University of Jos. The Nigerian
power sector continues to face infrastructural deficiencies, high transmission losses, and heavy
reliance on fossil fuels, leading to frequent power interruptions [1]. These disruptions negatively
affect academic activities, research, and administrative operations within institutions of higher
learning. To mitigate these challenges, this project combined two approaches: the design and
implementation of a 1kVA inverter prototype for educational demonstration, and the installation
of a 10kVA solar photovoltaic (PV) power system with lithium-ion battery storage for practical
departmental use.
The 1kVA inverter was designed as a teaching and learning model to reinforce theoretical
principles of power electronics and inverter operation. The system was divided into five main
functional units:
i.Oscillating unit: Utilizing a CD4069 IC to generate 50Hz square-wave pulses.
ii.Driver unit: Employing optocouplers and twelve IRFP150N MOSFETs arranged in
parallel to switch high current loads.
iii.Transformer unit: A custom-wound 24-0-24V to 220V step-up transformer to provide
the required AC output.
iv.Low-voltage alarm unit: Designed using a comparator, Zener diode, and 555 timer
circuit to protect against deep battery discharge.
v.Output stage: Where 24V DC input from the battery was successfully converted to
220V AC at 50Hz.
Simulation was first conducted using Proteus Design Suite, after which the hardware was
implemented. Testing demonstrated that the inverter could power resistive loads such as bulbs,
fans, and heaters up to its rated capacity of 1kVA. The system efficiency was approximately
85%, which is typical of square-wave inverters. Overload protection was confirmed when
attempts to draw beyond 1kVA triggered circuit shutdown, preventing component damage.
49
SUMMARY AND CONCLUSION
5.1 Summary of the Work
This research project was initiated to address the persistent challenge of unreliable power supply
within the Department of Electrical and Electronics Engineering, University of Jos. The Nigerian
power sector continues to face infrastructural deficiencies, high transmission losses, and heavy
reliance on fossil fuels, leading to frequent power interruptions [1]. These disruptions negatively
affect academic activities, research, and administrative operations within institutions of higher
learning. To mitigate these challenges, this project combined two approaches: the design and
implementation of a 1kVA inverter prototype for educational demonstration, and the installation
of a 10kVA solar photovoltaic (PV) power system with lithium-ion battery storage for practical
departmental use.
The 1kVA inverter was designed as a teaching and learning model to reinforce theoretical
principles of power electronics and inverter operation. The system was divided into five main
functional units:
i.Oscillating unit: Utilizing a CD4069 IC to generate 50Hz square-wave pulses.
ii.Driver unit: Employing optocouplers and twelve IRFP150N MOSFETs arranged in
parallel to switch high current loads.
iii.Transformer unit: A custom-wound 24-0-24V to 220V step-up transformer to provide
the required AC output.
iv.Low-voltage alarm unit: Designed using a comparator, Zener diode, and 555 timer
circuit to protect against deep battery discharge.
v.Output stage: Where 24V DC input from the battery was successfully converted to
220V AC at 50Hz.
Simulation was first conducted using Proteus Design Suite, after which the hardware was
implemented. Testing demonstrated that the inverter could power resistive loads such as bulbs,
fans, and heaters up to its rated capacity of 1kVA. The system efficiency was approximately
85%, which is typical of square-wave inverters. Overload protection was confirmed when
attempts to draw beyond 1kVA triggered circuit shutdown, preventing component damage.
49
However, due to its square-wave output, the prototype was not suitable for sensitive electronics
such as computers or laboratory instruments.
The second and more practical phase involved the design and installation of a 10kVA solar PV
system with lithium-ion battery storage for the department. Load estimation revealed an average
daily energy requirement of approximately 16.4kWh, covering essential appliances including
lighting, laptops, projectors, and laboratory trainers. Based on this analysis, the system
components were specified as follows:
i.Solar modules: Eight panels rated at 545W and 550W, arranged in series-parallel
configuration to achieve stable voltage (~82V) and current (~52A).
ii.Lithium-ion battery bank: A 15kWh storage system with ~90-95% round-trip
efficiency and depth of discharge up to 90%, enabling over six hours of backup
operation.
iii.Charge controller: An 80A MPPT controller regulating current flow and protecting the
batteries from overcharging and deep discharge.
iv.Inverter: A Felicity 10kVA inverter providing near-sinusoidal AC output at 220V,
suitable for powering sensitive electronics.
v.Cabling and protection devices: Appropriately sized DC and AC cables (10mm²,
2.5mm², and 1.5mm²), and miniature circuit breakers (MCBs) for selective coordination
and fault isolation.
Testing of the 10kVA installation showed excellent results. Socket outlets powered laptops,
projectors, and laboratory trainers effectively, while lighting points remained stable even during
prolonged use. The lithium batteries maintained system output well into the evening, ensuring
uninterrupted academic activities. Efficiency levels exceeded 90%, and the installation adhered
to both Nigerian wiring codes and international standards [2].
A comparative evaluation revealed that while the 1kVA inverter served mainly as a proof-of-
concept and educational tool, the 10kVA solar-lithium system provided practical solutions to the
department’s energy needs. The inverter prototype highlighted fundamental challenges such as
waveform quality and thermal management, while the larger system demonstrated scalability,
reliability, and sustainability when advanced technologies are employed.
50
such as computers or laboratory instruments.
The second and more practical phase involved the design and installation of a 10kVA solar PV
system with lithium-ion battery storage for the department. Load estimation revealed an average
daily energy requirement of approximately 16.4kWh, covering essential appliances including
lighting, laptops, projectors, and laboratory trainers. Based on this analysis, the system
components were specified as follows:
i.Solar modules: Eight panels rated at 545W and 550W, arranged in series-parallel
configuration to achieve stable voltage (~82V) and current (~52A).
ii.Lithium-ion battery bank: A 15kWh storage system with ~90-95% round-trip
efficiency and depth of discharge up to 90%, enabling over six hours of backup
operation.
iii.Charge controller: An 80A MPPT controller regulating current flow and protecting the
batteries from overcharging and deep discharge.
iv.Inverter: A Felicity 10kVA inverter providing near-sinusoidal AC output at 220V,
suitable for powering sensitive electronics.
v.Cabling and protection devices: Appropriately sized DC and AC cables (10mm²,
2.5mm², and 1.5mm²), and miniature circuit breakers (MCBs) for selective coordination
and fault isolation.
Testing of the 10kVA installation showed excellent results. Socket outlets powered laptops,
projectors, and laboratory trainers effectively, while lighting points remained stable even during
prolonged use. The lithium batteries maintained system output well into the evening, ensuring
uninterrupted academic activities. Efficiency levels exceeded 90%, and the installation adhered
to both Nigerian wiring codes and international standards [2].
A comparative evaluation revealed that while the 1kVA inverter served mainly as a proof-of-
concept and educational tool, the 10kVA solar-lithium system provided practical solutions to the
department’s energy needs. The inverter prototype highlighted fundamental challenges such as
waveform quality and thermal management, while the larger system demonstrated scalability,
reliability, and sustainability when advanced technologies are employed.
50
5.2 Conclusion
The successful completion of this project illustrates the potential of renewable energy systems
combined with modern power electronics to address Nigeria’s energy challenges. The 1kVA
inverter prototype demonstrated the feasibility of low-cost inverter construction, reinforcing
student knowledge of power conversion, component integration, and protective design. On the
other hand, the 10kVA solar PV installation with lithium-ion storage showcased the real-world
application of these principles by providing a stable, clean, and efficient source of electricity for
the Department of Electrical and Electronics Engineering.
The key benefits of this work include:
i.Reliability: The 10kVA system ensured uninterrupted power for offices, classrooms, and
laboratories.
ii.Sustainability: Solar energy reduced dependence on diesel generators, thereby lowering
carbon emissions.
iii.Cost-effectiveness: Although initial costs were high, the system promises long-term
savings through reduced fuel and maintenance expenses.
iv.Educational impact: The 1kVA inverter offered a platform for students to gain hands-on
experience with inverter design and testing.
Despite these successes, challenges were identified. The square-wave nature of the 1kVA
inverter limited its applications, highlighting the need for PWM-based or microcontroller-
controlled designs. Additionally, the high cost of lithium batteries poses financial barriers to
widespread adoption in Nigeria. Seasonal variability in solar radiation also limits continuous
energy availability without hybrid backup options.
Overall, this project provides both a theoretical contribution through the construction of a
demonstrative inverter and a practical contribution through the installation of a renewable energy
system that directly benefits the department. It stands as a model for sustainable energy adoption
in academic institutions across Nigeria.
51
The successful completion of this project illustrates the potential of renewable energy systems
combined with modern power electronics to address Nigeria’s energy challenges. The 1kVA
inverter prototype demonstrated the feasibility of low-cost inverter construction, reinforcing
student knowledge of power conversion, component integration, and protective design. On the
other hand, the 10kVA solar PV installation with lithium-ion storage showcased the real-world
application of these principles by providing a stable, clean, and efficient source of electricity for
the Department of Electrical and Electronics Engineering.
The key benefits of this work include:
i.Reliability: The 10kVA system ensured uninterrupted power for offices, classrooms, and
laboratories.
ii.Sustainability: Solar energy reduced dependence on diesel generators, thereby lowering
carbon emissions.
iii.Cost-effectiveness: Although initial costs were high, the system promises long-term
savings through reduced fuel and maintenance expenses.
iv.Educational impact: The 1kVA inverter offered a platform for students to gain hands-on
experience with inverter design and testing.
Despite these successes, challenges were identified. The square-wave nature of the 1kVA
inverter limited its applications, highlighting the need for PWM-based or microcontroller-
controlled designs. Additionally, the high cost of lithium batteries poses financial barriers to
widespread adoption in Nigeria. Seasonal variability in solar radiation also limits continuous
energy availability without hybrid backup options.
Overall, this project provides both a theoretical contribution through the construction of a
demonstrative inverter and a practical contribution through the installation of a renewable energy
system that directly benefits the department. It stands as a model for sustainable energy adoption
in academic institutions across Nigeria.
51
5.3 Recommendations for Future Work
i.To build on the successes of this project, the following recommendations are proposed:
ii.Adoption of Sine-Wave Inverter Designs: Future projects should implement pulse-width
modulation (PWM) or digital signal processing (DSP) techniques to generate pure sine
wave outputs, thereby improving compatibility with sensitive loads.
iii.System Hybridization: Incorporating a hybrid inverter capable of interfacing with both
grid and solar energy would enhance resilience during extended cloudy or rainy periods.
iv.IoT-Based Monitoring: Integrating smart energy monitoring systems would enable
remote performance tracking, predictive maintenance, and improved load management.
v.Expansion to Community Level: The system can be scaled to provide electricity for
larger facilities such as entire faculties, small hospitals, or rural communities.
vi.Local Production and Policy Support: Encouraging local assembly of lithium batteries
and government incentives for renewable energy projects could reduce initial costs and
accelerate adoption.
vii.Seasonal Performance Analysis: Long-term monitoring during the rainy season should be
conducted to evaluate system stability and design modifications for year-round operation.
5.4 Final Remark
This project has successfully achieved its objectives by merging academic learning with practical
application. The design and implementation of a 1kVA inverter prototype enhanced technical
competence in power electronics, while the installation of a 10kVA solar-lithium system
provided a functional solution to the department’s energy challenges. The outcomes demonstrate
the viability of renewable energy technologies in Nigeria, showing that through proper planning,
design, and implementation, engineering innovation can contribute meaningfully to sustainable
development goals.
52
i.To build on the successes of this project, the following recommendations are proposed:
ii.Adoption of Sine-Wave Inverter Designs: Future projects should implement pulse-width
modulation (PWM) or digital signal processing (DSP) techniques to generate pure sine
wave outputs, thereby improving compatibility with sensitive loads.
iii.System Hybridization: Incorporating a hybrid inverter capable of interfacing with both
grid and solar energy would enhance resilience during extended cloudy or rainy periods.
iv.IoT-Based Monitoring: Integrating smart energy monitoring systems would enable
remote performance tracking, predictive maintenance, and improved load management.
v.Expansion to Community Level: The system can be scaled to provide electricity for
larger facilities such as entire faculties, small hospitals, or rural communities.
vi.Local Production and Policy Support: Encouraging local assembly of lithium batteries
and government incentives for renewable energy projects could reduce initial costs and
accelerate adoption.
vii.Seasonal Performance Analysis: Long-term monitoring during the rainy season should be
conducted to evaluate system stability and design modifications for year-round operation.
5.4 Final Remark
This project has successfully achieved its objectives by merging academic learning with practical
application. The design and implementation of a 1kVA inverter prototype enhanced technical
competence in power electronics, while the installation of a 10kVA solar-lithium system
provided a functional solution to the department’s energy challenges. The outcomes demonstrate
the viability of renewable energy technologies in Nigeria, showing that through proper planning,
design, and implementation, engineering innovation can contribute meaningfully to sustainable
development goals.
52
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2020. [Online]. Available: https://web.archive.org/web/20201022000000*/battery-
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53
[1] I. E. Agency, "World Energy Outlook 2023," IEA, 2023.
[2] B. D. a. R. Pode, " Potential of lithium-ion batteries in renewable energy," in Renewable
Energy, 2015, pp. 375-380.
[3] C. Y. a. A. P. C. J. J. G.-H. Kim, "Comparison of different cooling methods for lithium ion
battery cells," in Appl. Therm. Eng, 2016, p. 846–854.
[4] "Different Battery Management System Topology," BMS Topologies Archive , 22 October
2020. [Online]. Available: https://web.archive.org/web/20201022000000*/battery-
management-topologies.
[5] O. M. A. a. J. M. Alabid, "Solar energy technology and its roles in sustainable
development," Clean Energy, vol. 6, no. 4, pp. 476-483, 2022.
[6] B. PowerSafe, "PCM vs BMS, a dilemma for product designers," BMS PowerSafe, 1 June
2016. [Online]. Available: https://www.bmspowersafe.com/.
[7] M. K. a. J. So, "VLSI design and FPGA implementation of state-of-charge and state-of-
health estimation for electric vehicle battery management systems," J. Energy Storage, vol.
73, p. 108876, 2023.
[8] Z. W. W. H. a. J. Z. H. Liu, "Thermal issues about Li-ion batteries and recent progress in
battery thermal management systems: A review," Energy Convers. Manag, vol. 150, p.
304–330, 2017.
[9] N. A. a. V. Balzani, "Solar electricity and solar fuels: Status and perspectives in the context
of the energy transition," Chemistry – A European Journal, vol. 22, pp. 32-57, 2016.
[10]allelco, "Understanding the CD4069 IC: Pinout, Specifications, Circuit Diagram, and
Uses," allelco, 13 Decenber 2024. [Online]. Available:
https://www.allelcoelec.com/blog/Understanding-the-CD4069-IC-Pinout-Specifications-
Circuit-Diagram-and-Uses.html?srsltid=AfmBOooDcTsKC6JBW9SI6-
eHgTnrRI2SKtBONVfaSPQrVIQ8wp2GLFt1.
[11]V. Semiconductors, "4N35 Optocoupler Datasheet," 7 january 2010. [Online]. Available:
https://www.vishay.com/docs/81181/4n35.pdf.
[12]T. Instruments, "LM78XX Datasheet," march 2013. [Online]. Available:
https://www.alldatasheet.com/datasheet-pdf/view/551877/TI1/LM78XX.html.
[13]V. Semiconductors, "IN4148 High-Speed Switching Diode Datasheet," 7 November 2024.
[Online]. Available: https://www.vishay.com/docs/81857/1n4148.pdf.
53
[14]S. A. a. O. Omoifo, "The Design and Construction of a 2kVA Inverter with Timing
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[16]M. M. a. R. Ruther, "Economic performance and policies for gridconnected," Energy
Policy, p. 688–694, 2012.
[17]U. (. N. D. P. U. (. N. I. D. O. IEA (International Energy Agency), "Energy Poverty-How to
make modern energ access universal," OECD/IEA, 2010.
[18]B. P. Dash V, "Power management control strategy for a stand-alone solar photovoltaic,"
Sustainable Energy Technol Assess, vol. vol IX, p. 68–80, 2015.
[19]J. B. &. P. K. S. Goodenough, "The Li-ion rechargeable battery: A perspective," Journal of
the American Chemical Society, p. 1167–1176, 2013.
[20]G. Pistoia, "Lithium-Ion Batteries: Advances and Applications," Elsevier, 2014.
[21]M. S. a. J. Petinrin, "Renewable energy potentials in Nigeria: Meeting rural energy needs,"
Renewable and Sustainable Energy Reviews, vol. 29, p. 72–84, 2014.
54
Capability for Load Supply," The Design and Construction of a 2kVA Inverter with Timing
Capability for Load Supply, 2014.
[15]REN21, "Renewables 2016 Global Status Reports," REN21, 2016.
[16]M. M. a. R. Ruther, "Economic performance and policies for gridconnected," Energy
Policy, p. 688–694, 2012.
[17]U. (. N. D. P. U. (. N. I. D. O. IEA (International Energy Agency), "Energy Poverty-How to
make modern energ access universal," OECD/IEA, 2010.
[18]B. P. Dash V, "Power management control strategy for a stand-alone solar photovoltaic,"
Sustainable Energy Technol Assess, vol. vol IX, p. 68–80, 2015.
[19]J. B. &. P. K. S. Goodenough, "The Li-ion rechargeable battery: A perspective," Journal of
the American Chemical Society, p. 1167–1176, 2013.
[20]G. Pistoia, "Lithium-Ion Batteries: Advances and Applications," Elsevier, 2014.
[21]M. S. a. J. Petinrin, "Renewable energy potentials in Nigeria: Meeting rural energy needs,"
Renewable and Sustainable Energy Reviews, vol. 29, p. 72–84, 2014.
54
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