ABSTRACT
Nowadays, increasing energy demand and dependence on fossil fuel become important issues
facing the whole world. Therefore, there is a big trend to use renewable energy sources (RES) to
address the electricity generation. Stable power supply today in Nigeria has drastically drop
because of the high cost of petroleum product. Most power plants and domestic generators
solemnly depends on fuel to power their appliances which today the cost of PMS is almost
unaffordable. The aim of this project is to develop a solar powered 1000watt mobile generator, a
100watt was determined by load assessment, solar panel number determination, battery
requirement and then inverter sizing. A complete solar panel rated at 100w was however
purchased, together with lithium batteries packed to give an output of 74Ah, 1000W inverter and
also 10A charge controller. These were assembled together with necessary protective gadgets
like cut out switches with a cooling system an alternative power supply charging system was
included as an alternative to charge the system. The solar panel was mounted outside the
building to allow for maximum collection of sun energy. It is expected that the system will help
the department meet up with its office duties even when central power is not available
i
Table of Contents
LIST OF FIGURES ......................................................................................................... vi
LIST OF TABLES .......................................................................................................... vii
CHAPTER ONE .............................................................................................................8
1.1 INTRODUCTION ..............................................................................................8
1.2 PROBLEMS DEFINITION ..................................................................................9
1.3 AIM AND OBJECTIVES .....................................................................................9
1.5 SCOPE OF THE PROJECT ................................................................................ 10
1.6 PROJECT MOTIVATION ................................................................................. 11
1.7
PROJECT LIMITATION ....................................................................................... 11
1.8 METHODOLOGY............................................................................................ 11
CHAPTER TWO .......................................................................................................... 13
LITERATURE REVIEW ................................................................................................. 13
2.0 INTRODUCTION ............................................................................................ 13
2.1 HISTORY OF SOLAR GENERATOR................................................................... 13
2.1.1
REVIEW OF SIMILAR WORK ....................................................................... 14
2.2 REQUIRED COMPONENTS ............................................................................. 15
ii
2.2.0
POWER SUPPLY UNIT................................................................................. 16
2.2.1 TRANSFORMER ........................................................................................... 17
2.2.2
RECTIFICATION .......................................................................................... 18
2.2.3 RIPPLE FILTERING ......................................................................................... 19
2.2.1 RELAY .......................................................................................................... 21
2.2.2
BATTERY MANAGEMENT SYSTEM............................................................. 22
2.2.3
20A MPPT CHARGE CONTROLLER ............................................................. 23
2.2.4
100WATT SOLAR PANEL ............................................................................ 24
2.2.5
MINI DC VOLTMETER................................................................................. 25
2.2.6
LITHIUM BATTERY ..................................................................................... 27
2.2.7
1000WATT INVERTER ................................................................................... 28
CHAPTER THREE ........................................................................................................ 30
DESIGN METHODOLOGY ........................................................................................... 30
3.0 PROJECT SPECIFICATION ............................................................................... 30
3.1 CIRCUIT OPERATION ..................................................................................... 31
3.2 SIZING OF THE SYSTEM ................................................................................. 32
3.3 SUN HOUR PER DAY ...................................................................................... 33
iii
3.4 DETERMINE NUMBER OF SOLAR PANEL ....................................................... 34
3.5 STORAGE BATTERY SIZING ............................................................................ 35
3.6 DETERMINE SOLAR CHARGE CONTROLLER ................................................... 36
CHAPTER FOUR ......................................................................................................... 37
DESIGN IMPLEMENTATION AND TESTING ................................................................. 37
4.0 PROJECT RESOURCE CENTERS....................................................................... 37
4.1.1
CHOICE OF MATERIALS .............................................................................. 37
4.2 DESIGN IMPLEMENTATION STEPS ................................................................ 38
4.2.1
RESULT ...................................................................................................... 38
4.3 DESIGN STEPS ............................................................................................... 38
4.3.1
COMPONENT PLACING AND WIRING......................................................... 38
4.3.2
COMPONENT SOLDERING.......................................................................... 39
4.4 INSERTING THE IC INTO THE HARDWARE DESIGN......................................... 39
4.5 CIRCUIT TEST ................................................................................................ 39
4.6 PACKAGING .................................................................................................. 39
4.7 DESIGN TEST AND ERROR CORRECTIONS ...................................................... 40
4.8 FINAL TEST .................................................................................................... 40
iv
CHAPTER FIVE ........................................................................................................... 41
RECOMMENDATION AND CONCLUSION.................................................................... 41
5.0 SUMMARY .................................................................................................... 41
5.1 PROBLEM ENCOUNTER ................................................................................. 41
5.2 SUGGESTION FOR FURTHER DESIGN............................................................. 42
5.3 RECOMMENDATION ..................................................................................... 42
5.4 CONCLUSION ................................................................................................ 43
REFERENCE ............................................................................................................ 44
v
LIST OF FIGURES
Figure 1 block diagram of the system ........................................................................................... 12
Figure 2 Power supply unit ........................................................................................................... 17
Figure 3 block diagram of a typical power supply unit ................................................................ 17
Figure 4 transformer ..................................................................................................................... 17
Figure 5 Shows the wave form of a bridge rectifier ..................................................................... 19
Figure 6 shows filtered DC output[3,1,2] ..................................................................................... 20
Figure 4 12v Relay ........................................................................................................................ 22
Figure 7 shows BMS..................................................................................................................... 23
Figure 8 20A MPPT charge controller ......................................................................................... 24
Figure 9 The 100watt panel .......................................................................................................... 25
Figure 10 Mini dc voltmeter ......................................................................................................... 27
Figure 11 Lithium cell .................................................................................................................. 28
Figure 12 1000watt inverter .......................................................................................................... 29
Figure 23 Circuit Diagram of the Design ..................................................................................... 31
Figure 24 system test .................................................................................................................... 39
vi
LIST OF TABLES
Table 1 sizing of system ............................................................................................................... 32
Table 2 sizing of inverter .............................................................................................................. 32
vii
CHAPTER ONE
1.1
INTRODUCTION
The general objective of the system is to provide efficiency, steadiness in the use of power
appliances, by ensuring continuous availability of power supply even in the absence of mains.
Uninterruptability of the system made it possible to eliminate all suspense from mains outage
during the execution of an important and urgent assignment as may be required. For better
production of the system, the system was operated at a fully charged condition of the battery.
The project was rated 100W of 220V and 50Hz. It was expected that at this condition, it was
favorable to carry load of the stipulated power. Loads of low power factors are not helpful since
they produce spikes. Overloading is not potent to provide zero change over time and the inverter
had LEDs which indicates mains failure and battery discharge and system fault
A power inverter, or inverter, is an electronic device or circuitry that changes direct current (DC)
to alternating current (AC). (The Authoritative, 2000). The input voltage, output voltage and
frequency, and overall power handling depend on the design of the specific device or circuitry.
The inverter does not produce any power; the power is provided by the DC source. A power
inverter can be entirely electronic or may be a combination of mechanical effects (such as a
rotary apparatus) and electronic circuitry. Static inverters do not use moving parts in the
conversion process. (Power Inverter, 2014)
A solar inverter, or PV inverter, converts the variable direct current (DC) output of a
photovoltaic (PV) solar panel into a utility frequency alternating current (AC) that can be fed
8
into a commercial electrical grid or used by a local, off-grid electrical network. It is a critical
balance of system (BOS) –component in a photovoltaic system, allowing the use of ordinary ACpowered equipment. Solar inverters have special functions adapted for use with photovoltaic
arrays, including maximum power point tracking and anti-islanding protection. (Solar Inverter,
2014)
This project work involves the design and construction a 1kVA mobile solar power inverter
system.
1.2
PROBLEMS DEFINITION
Uninterruptible power supply units are common electrical items found in most private and
industrial buildings in Nigeria as a result of the never-stable and not-always-available power
supply situation in the country. However, these units have not provided the much desired
reliable, efficient and effective power supply delivery to their owners because these not-veryintelligent units do not, most of the time, get energy to recharge their built-in batteries.
Hence, there is a need to design and implement a power inverter system that gets energy to
recharge its built-in battery from solar energy that is relative cheap and available.
1.3
AIM AND OBJECTIVES
The project aim is to design and fabricate a 100watt solar generator for a domestic operation.
The objectives are discussed as thus;
9
1. To develop a 1000watt inverter capable of powering little home appliances
2. To develop a solar system capable of charging a system within a fast time
3. To design a storage system using lithium battery technology
4. To design an automatic charging and change over system as an alternative source.
1.4
SIGNIFICANT OF THE STUDY
Human needs are numerous and the resources to satisfy these needs are limited and in most cases
scarce. Hence, there is a need to maximize these limited resources and to minimize waste of
these resources to the barest minimum. Energy (power) is one of those limited resources that
man needs to satisfy his numerous needs. The 1kVA mobile solar power inverter system seeks to
provide a means to adequately, harness the potentials of solar energy for power (energy)
generation for domestic usage.
1.5
SCOPE OF THE PROJECT
This solar power source makes it possible to provide a clean reliable supply of alternative
electricity free of sags or surges which could be found in the line voltage frequency. The solar
power system (SPS) system achieved this by direct current from solar panel and by rectifying the
standard main supply, using the direct current to charge the batteries and to provide clean
alternative power by passing the energy a filter system. It has zero change over time and LEDs
which indicates mains fail and battery discharge level and it provides 100% protection against
line noise, spikes surges and audio frequency interference.
10
1.6
PROJECT MOTIVATION
Most of this equipment are not locally gotten especially by engineering institutions in Nigeria.
They are expensive to buy and often import from foreign countries. Most African countries like
Nigeria depends so much on power to sustain their businesses.
The high cost of petroleum product most especially the Premium Motor Spirit (PMS) which has
been the major source of most domestic power combustion generators and the unstable power
supply that is annihilating the economy of the country instigated me to develop a system that is
capable of powering house appliances using green energy.
1.7
PROJECT LIMITATION
The portable solar power generator is designed to handle some of the domestic appliances such
as, lighting, plasma TV, standing fan, charging of phones/ laptops and any other electrical
equipment that is less than or equal to the wattage of the system. It cannot handle an inductive
load of power greater than 1000watt, such as electric iron, fridges, electric cooker, e t c, for it is
designed for domestic appliances of less than or equal to 1000watt.
1.8
METHODOLOGY
The solar generator comprises of a 100watt solar power panel that is connected to a 20A charge
controller to charge up a 74AH lithium batteries. The lithium batteries were packed together in a
metal box 3 sets of 11 pieces in parallel in series, they were all connected to a battery
management system (BMS) to maintain a safe and even charge and discharge of the lithium
pack. A 1000watt inverter was connected on the battery pack with a cooling system to always
11
ensure the working temperature is within the operating temperature. A power supply with an
automatic changeover was also interfaced to the system as an alternative means of charging the
battery in the absence of sun. The system is shown in the block diagram below
.
100watt panel
Charge
controller
& BMS
74AH
lithium
1000wat
t inverter
Automatic
changeover
and
Charging
Figure 1 block diagram of the system
12
AC load
CHAPTER TWO
LITERATURE REVIEW
2.0 INTRODUCTION
This chapter carried a conceptual discourse of power supply of the system and established the
relationship between them. It also reviewed some literature in a field of study to identify the gap
to be filled by the research.
Furthermore, a theoretical frame work to properly situate the study was presented.
2.1 HISTORY OF SOLAR GENERATOR
The use of the sun’s energy is nothing new and dates back to the beginning of time. In recent
years however, the focus on energy consumption worldwide rapidly spurred growth in the
research and development of ‟ green” alternative fuel source including the sun, wind, hydro,
wave, geothermal, hydrogen and other forms of energy. And today, because of that focus, the use
of solar energy is expanding by leaps and bounds especially since sunlight is free, unlimited,
readily available, clean and reliable. A solar power system is one which is capable of converting
the absorbed sun energy; store it in a lead acid cell to be used on the load. In our part of the
world, where power supply is not effective and efficient, the use of solar power supply is of
immerse value and advantage considering the fact that we are blessed or rich in sun light i.e. high
degrees of temperatures which is the main thing that feeds a solar power supply unit for uses. It
is low cost compared to other alternative sources of power supply in this society e.g. the use of
generators which consume fuel or diesel and are really expensive, and its life span is better and
reliable when used under or within or above the stipulated rating of the solar power device.
13
2.1.1
REVIEW OF SIMILAR WORK
Zafri A.A et al. [1] The main goal of this study was to design and develop a solar generator that
can generate 20 Watts of electricity. This amount of power can supply up to 96 hours of
electricity for the purpose of lighting and running small electrical appliances. The power output
is (alternating current) AC current using 150 Watts inverter with 200 Watts surge, suitable for all
commercial single phase electric appliances. Solar charge controller is used to maximize the
charging rate and to protect the battery.
Ezugwu Chika et el [2] This project has 200W solar system was determined by load assessment,
solar panel number determination, battery requirement and then inverter sizing. A complete solar
panel rated at 200w was however purchased, together with 2 no. 150A solar battery, 1500W
inverter and also 10A charge controller. These were assembled together with necessary
protective gadgets like cut out switches; to give the 200W expected. The solar panel was
mounted outside the building to allow for maximum collection of sun energy.
Omosanya H. A et al. [3] This project is about the design and construction of 2KW 230 volts
solar panel inverter at a frequency of 50Hz.The device is constructed with locally sourced
components and materials of regulated standard. The basic principle of its operation is a simple
conversion of 12V DC from a battery using integrated circuits and semiconductors at a frequency
of 50Hz, into a 230V AC across the windings of a transformer. A solar panel is used to charge
the battery using a solar charge controller. This project (device) offers a better alternative to
Public Power Supply, Generators as well as UPS considering it is cost effective, noiseless and
easy maintainability
14
drive arrangement. The free-wheel, thus, also starts rotating in counter clockwise direction. As
freewheel and big spur gear are mounted on same shaft, it also start rotating in anticlockwise
direction.
Raji A. 2021 constructed an electric sprayer using 4ah battery with a 20watt panel and a charge
controller that work quit well but only within a few period of time.
Abdulwahab A. 2022 constructed an automatic sprayer for small scale farmer using a dc pump, a
lead acid battery, 20watt solar. The lead acid battery was very heavy which added more weight
to the system, the charging process was slow and theirs was more current loss on the cable for
switching the pump
The system developed was able to counter all the limitations above, the lithium battery which has
an efficiency of 99.9% was used, and a relay was used to switched ON the pump which
increased the efficiency of the pressure generated by the system. An MPPT charge controller
was used to improve the charging efficiency of the system.
.
2.2

REQUIRED COMPONENTS
Lithium battery
15

20A MPPT charge controller

Relay Module

Battery Management System (BMS)

Limit switch

DC voltage meter Display

1000watt inverter

switches

100watt Polycrystalline Panel

Power supply

Wires, jack and plugs
2.2.0 POWER SUPPLY UNIT
The power supply unit consists of the following. Transformer, Rectifier, Regulator and Filter
unit. The circuit below (fig2.4a) shows the circuit diagram of a typical power supply unit.
16
Figure 2 Power supply unit
INPUT
TRANSFORMER
RECTIFIER
FILTER
REGULATOR
OUTPUT
Figure 3 block diagram of a typical power supply unit
2.2.1 TRANSFORMER
A transformer is a static electronic device by means of which electronic power in one circuit is
transformed into electronic power of the same frequency in another circuit. It can raise or lower
the voltage in a circuit but with corresponding decrease or increase in current. The physical
basis of a transformer is mutual induction between two circuit linked by a common magnetic
flux (D).
Figure 4 transformer
The two coils possess high mutual inductance. If one of the coils connected to a source of
alternating voltage. An alternating flux is set up in the laminated care, most of which is linked
with the other coils in which it produces mutually induced e.m.f.
If the second coil circuit is
closed, a current flow in it and so electric energy is transferred from the first coil to the second
coil.
The first coil, in which electric energy is fed from the AC supply mains, is called
PRIMARY
winding and the other from which energy is drawn out is called SECONDARY
winding. [1, 3]
17
There are two types of transformer:
i.
Step up transformer
ii.
Step down transformer
The type of transformer used in this project is STEP-DOWN transformer. A step down transform
is a transformer that changed electric power from high level to low level; the primary winding is
less than the secondary winding. The transformer rating used is 240/12v[6,3,2].
2.2.2 RECTIFICATION
A rectification is the process of converting an A.C voltage into pulsating D.C voltage. The circuit
responsible for rectification is known as rectifier circuit. Rectification can achieve by the use of
semiconductor diodes.
Rectification is classified into:
i.
Half wave rectification
ii.
Full wave rectification
iii.
Full wave (Bridge) rectification
However, full wave Bridge rectification would be discussed as it is the type of rectification that
is employed in this project (3).
18
FIG 3
Figure 5 Shows the wave form of a bridge rectifier
In full rectification, both half cycle of the input are utilized with flux half of four diodes working
alternatively. In this case, use of a transformer is essential.
When the A.C input supply is switched on, the M and N of the transformer secondary became
+ve and –ve respectively. During the +ve input half-cycle, terminal M of the secondary is
positive as N is – ve0 Diodes D1 and D3 became forward – biased (ON) where as D2 and D4 are
reversed – biased (OFF). Hence the current flows along MEABCFN producing a drop across R L
during the – ve half – cycle, secondary terminal N becomes +ve and M –ve. Now D2 and D4 are
forward – biased. Circuit current flows along NFABCEM. [1]
2.2.3 RIPPLE FILTERING
By the analysis of Fourier series, we know that a rectified sine wave consist of a DC components
and harmonics of the supply frequency. These harmonics are responsible for the ripples which
is not desPotentiometerable. For smooth operation is achieved here by the use of a capacitor
19
filter. The process of removing these ripples is known as filtering. A ripple filter is basically a
low pass filter that the DC component and alternatives the A.C compact as show in fig. 2.3.3.
The five main types of filter circuit are:
i.
Capacitor filter
ii.
Resistance capacitance (RC) filter
iii.
Inductance of choke – capacitance filter (LC)
iv.
R-L-C filters
v.
Series induction filter.
Figure 6 shows filtered DC output[3,1,2]
The power system is consist of 33 6.8AH lithium batteries connected in series and parallel in
such a way to give an output of 12.6V 74AH to the 1000watt inverter then to the load. And the
battery is isolated from the load by a management system BMS that also controls the even charge
of the series battery streams. The charger controller is highly efficient as it charges the battery
within a short period.
20
Lithium power
Lithium
BMS
pack
charger
Figure 7 block diagram of a typical power supply unit
2.2.1 RELAY
A relay is an electrically operated switch. Many relays use an electromagnet to mechanically
operate a switch, but other operating principles are also used, such as solid-state relays. Relays
are used where it is necessary to control a circuit by a separate low-power signal, or where
several circuits must be controlled by one signal.
Relays work on electromagnetism, When the Relay coil is energized it acts like a magnet and
changes the position of a switch. The circuit which powers the coil is completely isolated from
the part which switches ON/OFF, This provides electrical isolation. This is the reason we can
control a relay using 12V’s from an integrated circuit and the other end of it could be running a
220 to 240V appliance, the 240V end is completely isolated from the 12V integrated circuitry.
21
Figure 7 12v Relay
2.2.2
BATTERY MANAGEMENT SYSTEM
The Lithium-Ion batteries though have high energy density and light in weight, are very
dangerous if abused i.e., if you overcharge or undercharge the battery or draw more current than
it can provide then it can explode damaging the surrounding or even potentially harm the humans
around. To prevent this to happen you should use your batteries with a protection board. This 3S
Lithium-ion Battery Protection Board monitor protects three cells connected in series by
monitoring the voltage and current in and out of the battery pack and if any unsafe condition
happens then it will cut off the battery from the load or the charger. This can be used in any DIY
project where the current does not exceed 20A like Arduino or Raspberry Pi based projects, 3D
printers, Quadcopters, Robotics applications etc. This Board is suitable for 18650 cell having
nominal voltage of 3.6V or 3.7V.
22
Figure 8 shows BMS
2.2.3
20A MPPT CHARGE CONTROLLER
MPPT controller's full name "Maximum Power Point Tracking" solar controller is an upgraded
product of the traditional solar charge and discharge controller. MPPT controller detects the solar
panel's generated voltage in real time and tracks the highest voltage and current value (VI),
allowing the system to charge the battery with maximum power output. It is the brain of
photovoltaic system used in solar photovoltaic systems to coordinate the work of solar panels,
batteries and loads. When the solar panel is shadowed or part of the panel fails resulting in
multiple peaks on the I-V curve, the controller is still able to accurately track the maximum
power point.
A built-in maximum power point tracking algorithm can significantly improve the energy
utilization efficiency of photovoltaic systems, and raise the charging efficiency by 15% to 20%
compared with the conventional PWM method. A combination of multiple tracking algorithms
enables accurate tracking of the optimum working point on the I-V curve in an extremely short
time. The product boasts an optimum MPPT tracking efficiency of up to 99.9%. The controller
23
supports standard Modbus protocol, fulfilling the communication needs of various occasions.
The controller employs a built-in over-temperature protection mechanism. When temperature
surpasses the set value, the charging current will decline in linear proportion to the temperature
so as to curb the temperature rise of the controller, effectively keeping the controller from being
damaged by overheat. Featuring a temperature compensation function, the controller can
automatically adjust charging and discharging parameters in order to extend the battery’s service
life.
Figure 9 20A MPPT charge controller
2.2.4 100WATT SOLAR PANEL
The 40watt solar panel has an output of 2.4 amps of DC power during peak solar hours. This
panel must be used with a controller, as it is large enough to overcharge batteries without one. 40
watts of solar can be used for charging and maintenance of 12volt batteries up to about 250amp
hours of capacity and replace energy consumption, giving from 9 to 17 amps or more in a day.
24
This can be appropriate for remote telemetry, radio repeaters, LED signs, RV battery
maintenance, and other such applications where the amp draw fits the output. The BSP4012 solar
panel is an aluminum framed, commercial grade unit for long term exterior use, and has 15 feet
of UV resistant cable permanently attached.
.
Figure 10 The 100watt panel
2.2.5 MINI DC VOLTMETER
The power supply has a large screen
display and high measurement accuracy.
Suitable for all kinds of high capacity
25
battery type, such as lithium battery,
power bank, test board, etc. The product
is equipped with led display and can be
used normally in low light conditions.
Equipped with led display, it can visually
display the measured value and
operating parameters. mini digital
voltmeter ammeter detector: This is an
ordinary digital multimeter with true
rms, high accuracy, anti-interference
ability and reliability. This product is a
new type of energy meter with high
reliability and large measuring range,
high precision, easy to use and also has a
current voltage meter. This product is a
multifunctional ac current measuring
instrument with a clear lcd display and
backlight, which can be used as a normal
power supply for mobile phones.
26
Figure 11 Mini dc voltmeter
2.2.6 LITHIUM BATTERY
The A lithium-ion battery or Li-ion battery is a type of rechargeable battery composed of cells in
which lithium ions move from the negative electrode through an electrolyte to the positive electrode
during discharge and back when charging. Li-ion cells use an intercalated lithium compound as the
material at the positive electrode and typically graphite at the negative electrode. Li-ion batteries have a
high energy density, no memory effect (other than LFP cells) and low self-discharge. Cells can be
manufactured to prioritize either energy or power density. They can however be a safety hazard since
they contain flammable electrolytes and if damaged or incorrectly charged can lead to explosions and
fires.
27
M. Stanley Whittingham discovered the concept of intercalation electrodes in the 1970s, and invented
the first rechargeable lithium-ion battery, which was based on a titanium disulfide cathode and a
lithium-aluminum anode, patented in 1977, and assigned to Exxon.[11] John Goodenough expanded on
this work in 1980 by using lithium cobalt oxide as a cathode.[12] A prototype Li-ion battery was
developed by Akira Yoshino in 1985, based on the earlier research by John Goodenough, M. Stanley
Whittingham, Rachid Yazami and Koichi Mizushima during the 1970s–1980s,[13][14] and then a
commercial Li-ion battery was developed by a Sony and Asahi Kasei team led by Yoshio Nishi in
1991.[15] Lithium-ion batteries are commonly used for portable electronics and electric vehicles and are
growing in popularity for military and aerospace applications.[16]
.
Figure 12 Lithium cell
2.2.7 1000WATT INVERTER
One thousand watts is a typical inverter size that can provide power for various appliances and
electronics. 1000 watts happens to be a typical wattage for microwaves. 1000watt inverter is
perfectly sized to power one microwave oven. This might not sound impressive but consider how
quickly a microwave can cook your food. This 1000 watts is just about the most power use
you’re going to find from any individual appliance other than electric heating systems. The
28
challenge here is whether 1000 watts is sufficient to provide power for multiple uses at once. If
you have efficient LED bulbs in your home, it’s enough to keep the lights on many times over. If
you’re using a 1000 watt inverter on the go, you’ll likely have more than enough capacity for
anything you could possibly need. You could charge nearly 20 cellphones at once or run at least
ten laptops. You could even run several large televisions simultaneously. One thousand watts is
great for charging just about anything, making it an excellent addition for long trips. It can be
particularly useful for remote worksites where it can provide convenient charging for power
tools and some other modern conveniences.
Figure 13 1000watt inverter
29
CHAPTER THREE
DESIGN METHODOLOGY
3.0 PROJECT SPECIFICATION
This is the design and construction of a 220v portable solar power generator for the innovative
and sustainable solution for off-grid power needs. Each component of the system was designed
to efficiently supply a constant power to the submissive home appliances. It comprises of a
lithium battery cell arrange in a way that the output capacity is 44,000mAH, a 100watt poly
crystalline solar power was connected to a 20A maximum power point tracking (MPPT) charger
controller to charge the lithium batteries through a battery management system (BMS). The
battery management system is capable of delivering 20A of current to the inverter and also to
ensure even charge and discharge of the lithium batteries. The loads are 3watt lamp, 10watt
phone charger, 65watt laptop charger slot, TV plasma, 100watt, standing fan, 70watt for
domestic use.
30
3.1 CIRCUIT OPERATION
The system comprises of 33, 4000mAH lithium batteries, connecting eleven pieces in parallel in
three places and the three streams in series such that the output ratting is 12.6V and 44000mAH.
Each termination of the terminals is connected from the negative to the positive on a 20A battery
management system BMS, then the output of the BMS is connected to the charge controller. The
system is switched by a 10A 12V relay which is triggered by a limit switch connected to the
input of the AC charger .
.
Figure 14 Circuit Diagram of the Design
31
3.2 SIZING OF THE SYSTEM
What most people do first is to make a list of the power consumption of all the electrical
appliances and devices that will be used in their particular home or location and an estimate of
how long each appliance or device is switched –ON using energy each day. Once this is
complete multiply the power consumption (in watt) of each device by the number of hour it is on
to give you the daily electrical consumption in watt-hour as show below.
APPLIANCES
WATTS
HOUR/DAY
WATT-HOUR/DAY
One 3watt bulb
3W
5
15Watt-hours
Phone Adapter
10W
5
50Watt-hours
System Adapter
65W
3
195Watt-hours
Plasma TV
100W
5
500Watt-hours
Standing fan
70W
3
210Watt-hours
Total watt hours
=970 watt hours
Table 1 sizing of system
APPLIANCES
WATTS
MULIPLIER
TOTAL POWER USAGE
One bulb
3W
1.3
3.9W
Phone Adapter
10W
1.3
13W
System Adapter
65W
1.3
84.5W
Plasma TV
100W
1.3
130W
Standing Fan
70
2
140W
Total
371.4W
Table 2 sizing of inverter
32
Then the total energy consumption is estimated at around 970watt hours or 0.97kwh per day.
However, it is better to add a little extra on top, say 10% – 25% to account for losses in the
system or the use of an extra electronic device not accounted for. Thus, the new estimated value
would be 970watt-hours X 1.3 (25% extra) =1261
Inverter size =Total power consumed by AC Loads*Safety Factor
It is seen from the above table that the total power of the system is 371.4W,
We go for the nearest inverter size in the local market and is 1000Watt inverter. That means
approximately, 750VA/12V inverter
3.3 SUN HOUR PER DAY
As solar power generation is based on incident sunlight on the PV panel rather than heat, it is
necessary to know how many hours of direct sunlight the panel will be expose too throughout the
day. A clear exposure to the sun for most of the day is 9am to 4pm solar PV panel produces the
most power when it is pointing directly to incident sunlight, so that the suns ray shine straight
down onto its surface. Solar panel orientation is important as any panels should be located and
angled to where they will receive as much sunlight as possible, average out during the course of
the day, a month or a full year. Fortunately, most homes gardens and wheelbarrow solar system
have good access with roof that are often free from obstruction that can shade the solar panels.
The measurement for the strength of the sunlight striking the earth at your location is defined as
solar insolation and you will need to know the peak sun-hour figure for your location. Having a
good solar site is important to ensure that the PV panels are exposed to bright sunlight every day
of the year. It also ensures you are collecting the solar power more effective as well. Generally
33
during the winter season this can be low as 4 –hours or as high as 66-hours during summer
season.
Let assumes then that for our particular location the lowest solar insolation occurs during the
month of January with 6 hours of sunshine per day. Therefore, the total peak power generated by
the sunlight in the month of January will be 292.5 watt-hours/ 6hours = 48.75watt-peak.
3.4 DETERMINE NUMBER OF SOLAR PANEL
We already have an accurate idea of the solar insolation for a particular site, we have done the
electrical loads list survey so we know how much electric power we require on an average day.
All that remains is to specify the type and number of photovoltaic (PV) panels that will produce
the required power of 100watts.
Solar panels can also have different voltage ratings depending upon their construction and size.
Those that produce 18 to 48 volts outputs are generally used for off-grid applications. Maximum
power (Pmax) delivered by a single panel at full sun is given as maximum power voltage (Vmp)
time maximum power current (Imp). For our particular off-grid example we require battery
storage and backup so the system will be powered using 12 Vdc photovoltaic solar modules for
convenience.
So again, let us assume that we have done our research on panel availability, price, and size, and
we have decided to use 23volts 100wp solar panel with the following electrical specification: PM
=100wp, vmp = 23.3vdc, Imp =5.7A, Voc = 21v, Isc = 6.2A.
Thus, the total number of PV panel require will be 50wp/100wp = 0.5 = 1 solar panel rounded
off to the nearest whole panel.
34
So our portable solar power system will be powered by one 100 watt solar photovoltaic panel.
3.5 STORAGE BATTERY SIZING
Unfortunately the sun does not always shine, especially at night, so some additional backup is
required. During a nice sunny day, the solar panel can produce a lots of electrical power so to
allow us to use the wheelbarrow for rural system or during period of low solar insolation, we eill
need batteries to access that power after the sun goes down.
The amount of energy that will be consumed per day on the solar wheelbarrow system was
calculated at 39 watt-hours. This is the maximum amount of storage capacity we need for one
day Next we need to determine the number of days of battery backup that we want to have on
hand. This is called Autonomy.
Days of autonomy represents the number of cloudy in a row that might occur and for which the
batteries will need to supply energy to the loads. A standard number of autonomy days are
usually 3 days. Then the total amount of energy required for a minimum of three days of storage
for charging of phone, laptops and bulb that consumes 39 watt-hour daily is calculated
Appliance use 39wh/day, nominal battery voltage=12.6volts, days of autonomy will be 3 days
and efficiency=85%
Battery capacity=(292.1x1)/(0.99x12) the total ampere-hours required is therefore 74.8Ah or
greater of battery capacity at 12 volts.
35
3.6 DETERMINE SOLAR CHARGE CONTROLLER
All solar power system with batteries as backup should include a solar charge controller to
prevent the batteries from over charging and also to prevent the batteries from sending their
charge back through the system to the solar panels during times of low sun (i e, night time).
Since a solar controller does it work in line between the solar panel array and the storage
batteries, it makes sense that its selection and sizing is influence by those components.
Voltage and current are the two parameters used in solar charge controller sizing . The solar
controller must be capable of accepting the maximum power produced by the solar panels while
delivering the proper Dc voltage and charging current to the batteries.
For system in continuous operation the industry standard 1.2 (20% extra) de-rating factor is
specified to prevent the controller from becoming damaged due to excess solar panel current or
power. The solar panel above have a short circuit current (Isc) of 6.2A. The solar charge
controller rating will therefore be: 1 x 6.20 x 1.2 = 7.44A or 20Amps so the solar charge
controller should be 20A at 12.6 volts.
36
CHAPTER FOUR
DESIGN IMPLEMENTATION AND TESTING
4.0 PROJECT RESOURCE CENTERS
This includes:
a. Internet resource centers
b. Experimental aids and observation
c. Teachers and lectures
d. And digital electronics by J.K Mehta
4.1.1 CHOICE OF MATERIALS
The materials used were from the information gotten from the internet and the work was
developed through the source gotten online that was treating the same case.
The circuit diagram used is the diagram which was design as a prototype but also works to revive
some information about the circuit analysis of the devices which later entered more design like
the Potentiometer sensor that was well tested and ensured is adjusted based on the value
prescribed.
37
4.2 DESIGN IMPLEMENTATION STEPS
Care was taken while soldering the connections any mismatch or carelessness will easily fry your
components. Ordinary solders might not be able to withstand 3A, this will lead eventually melt
your solder and cause short circuit. Use thick copper wires or use more lead while connecting the
high current tracks as shown in the picture. Any short circuit or weak soldering will easily burn
your transformer windings; hence check for continuity before powering up the circuit. For
additional safety fuse on Input side can be used. High current voltage regulators mostly come in
metal can packages, while using them on dot board do not place components close to them as
their body acts as the output of the rectified Voltage, further will result in ripples. Also do not
solder the wire to the metal can, instead use a small screw as shown in the picture given below.
Solders don't stick to its body, and heating results in damaging the Regulator permanently. check
for overheating of the lithium batteries to ensure it is working at a safe temperature
4.2.1 RESULT
Evaluation of the construction was done by running testes on the device to measure its
performance and the battery capacity:
4.3 DESIGN STEPS
These are the various steps we took on the design of this project.
4.3.1 COMPONENT PLACING AND WIRING
Here, the whole components were place into the Casing box according to its position in the
block diagram.
38
4.3.2 COMPONENT SOLDERING
The lithium batteries and other component were soldered using a soft thick lead oxide, and the
component connections was done with a tiny flexible wire we got from a networking cable to
join one component to the other according to the circuit diagram.
4.4 INSERTING THE IC INTO THE HARDWARE DESIGN
Then after that the IC will now be inserted into the circuit for testing.
4.5 CIRCUIT TEST
After the fabrication of the system, the inverter was put to test after the lithium batteries were
fully charged under the sun. A 60watt soldering iron was connected to the system and operates
normal. It was tested at the front of SKILL-G laboratory with a soldering iron, a 65watt monitor
was used to test other little devices like charging of phones etc.
Figure 15 system test
4.6 PACKAGING
As a prototype design, we have to copy an existing system which was based on timing.
The packaging was done on a predefined modeling designed by an architect. And placement of
all sections of the circuits were done together with the LED display using glue gum, araldite and
other holding materials.
39
4.7 DESIGN TEST AND ERROR CORRECTIONS
After the packaging some errors was discovered due to wrong packaging which affected the
reading by the Potentiometer sensors taking random readings to cause the display to read
wrongly, but was corrected. Below is the work during testing and correction.
4.8 FINAL TEST
The final test was undergone for proper function and design usage. As shown in the diagram
below.
40
CHAPTER FIVE
RECOMMENDATION AND CONCLUSION
5.0 SUMMARY
This section of this project report forms the concluding part of the write up and takes a look at
some of the problems encountered during the progressive job on the system and also brings in
suggestions for further improvement and/or enhancement for the system design since the
construction was limited to just voltage alone, a current sensor could be added to measure the
output current of the of the loads.
The design and development of this project has really been challenging, as I have been faced
with choices far beyond what I expected. But in the long run the result paid off.
After the complete design of the system, the deviation between the expected result and the actual
result was very close. The performance and efficiency was beyond expectation and from every
ramification, the design of the project was a success.
5.1 PROBLEM ENCOUNTER
During the course of the design of this system, there were series of problems which came in the
way of achieving the design goals of this project, most of them where over come via share
troubleshooting, in some cases some part requires redesigning and debugging also created a bit
of a problem especially the placement of the proximity sensors which randomly adjust itself from
surrounding objects if not properly mounted.
41
One major setback of this project is the availability of components required to build the hardware
of the system. In most cases I had to look through electrical catalogs to obtain replacements of
some of the components which are not available in the market.
The final packaging of the design was also another trouble, as this actually caused problems on
the casing box. Such problems include partial contact within the casing box, between
components and also with the wiring. This was actually one of the most challenging aspects of
the system construction phase. Due to this fact, there was a lot of connection and dis-connections
to ensure that the system was well constructed.
5.2 SUGGESTION FOR FURTHER DESIGN
It will be more appreciated if the system is designed for switching AC load. And also with the
rise in the need of higher rated solid devices like MOSFET, Thyristor, Triacs and even Relays,
the need of implementing a fully operational switching system can be achievable.
5.3 RECOMMENDATION
a. Despite the control power box was covered with the panel, avoid water spillage on top of
the design.
b. Since a fuel car pump was used which was not made for the purpose, water may cause
oxidation and corrosion the fuel pump may not last, I recommend in the next design a car
wiper water pump should be used, it consumes less power and rugged for the system.
42
5.4 CONCLUSION
This project demonstrates the implementation of a solar generator that can be used in rural and
remote areas where there is no availability of power,. With the hike in fuel and other petroleum
products, this system is the best alternative for generating electricity in small quanivetity. The
performance will be satisfactory under laboratory condition. The model will give a fairly good
rate of area coverage and the cost of operation as calculated was also reasonable.
In addition, the safety and long term operation of the system is normal and safe since fabrication
is on MBF wood.
It does not compromise the performance of a manual and petrol base
generator, rather improved soft operation by the user.
The future scope of this project include:
Take up build a full-scale prototype which can be utilized in the fields in real time.
43
REFERENCE
[1] 1Gupta P K. 1979. ‘Human body response to vibrations induced by an experimental power
knapsack equipment’. M Tech thesis, Punjab Agricultural University, Ludhiana.
[2] FAO. 1994. Pesticide application equipment use in agriculture. Manually Carried Equipment,
Vol 1. Food and Agriculture Organization, Rome
[3] RNAM Test Codes and Procedures for Farm Machinery, pp 171.
[4] Miller A and Bellinder R. 2001. Herbicide application using a knapsack sprayer. Rice-Wheat
Consortium for the IndoGangetic Plains, New Delhi, p 12.
[5] Awulu J O and Sohotshan P Y. 2012. Evaluation of a developed electrically operated
knapsack sprayer. International Journal of Science and Technology 2(11): 769–72.
[6] P. Schertz, ‘Practical Electronics for Inventors’, Mc Graw Hills, 2nd edition, 2000, ISBN- 001-058078-2
[7]
Taufik.
The
DC
House
Project.
September
2010.
CalPoly.
March
2012.
http://www.calpoly.edu/¬taufik/dchouse/index.html. [Accessed on January 9, 2015].
[9]
Paul A. Lynn, Electricity from Sunlight: An IntroductiontoPhotovoltaics, Wiley; 1
edition, May 17, 2010.
[10]
Number of cell phones worldwide Hits 4.6B. February 2010. CBS News. March 2012.
http://www.cbsnews.com/2100-500395_162-6209772.html.[Accessed on March 17, 2015].
44
[11]
How to make a solar iPod/iPhone charger –aka Mighty Minty Boost by Honuson May 2,
2009.http://www.instructables.com/id/How-to-make-a-solar-iPodiPhone-charger-aka-Might/.
[Accessed on December 2, 2014].
45