FULL NAMES: Kabo Dikatholo
STUDENT ID: 1513697
Programme: Electrical Engineering
PROJECT TITLE: Solar Home System
Project Report
This project is submitted in partial fulfilment of the requirements for the degree of BEng in Electrical
Engineering of Faculty of Engineering & Applied Sciences, Botho University on 01/12/2020.
1
DECLARATION
I have read and understood the University Regulations concerning plagiarism and I undertake:
o That all material presented for examination is my own work and has not been written for me, in
whole or in part by any other person(s).
o That any quotation or paraphrase from the published or unpublished work of another person has
been duly acknowledged in the Research project.
o That I have not incorporated in this Research project without acknowledgement any work
previously submitted by me for any other module forming part of my degree.
2
Table of Contents
Cover /Title page………………………………………………………………………..1
Declaration……………………………………………………………………………...2
Table of Contents……………………………………………………………………….3
Abstract…………………………………………………………………………………4
Acknowledgements…………………………………………………………………….5
Chapter One: Introduction.…………………………………………………………….6
Chapter two: Review of related literature…….……………………………………….8
Chapter Three: Methodology…….……………………………………………………11
Chapter Four: Presentation and analysis of result……………………………………16
Chapter five: Discussion and interpretation of results………………………………..19
References…………………………………………………………………………….20
ABSTRACT
3
The aim of this research project is to design a Solar Home System. A Solar Power System can be off
grid or on grid but on this research focuses on the off grid solar power system. The design of a solar
home system consists of a solar panel, Battery, charge controller, circuit breaker panel, an inverter and
lights and appliances of the households. People are switching to solar power system as Botswana has
high irradiance levels and this is also due to electricity cuts and high bills. Even industries are
switching to solar power system.
ACKNOWLEDGEMENTS
4
I would like to be grateful to my lecture Mr E. Chikuni for leading me through this research and
helping me on how to go about it. I would also love to thank Mr Bokang Cedric who owns a solar
home system and allowed me to look at his appliances and how they run. If it wasn’t for this people
this project would not have been a success.
CHAPTER ONE: INTRODUCTION
5
GENERAL BACKGROUND
Solar Home System is being standardized in many homes and people are switching to it because of
many good reasons: solar home system protects from growing energy prices around, it reduces power
bills, it also helps protect the atmosphere from carbon emission from greenhouse gasses, and many
more reasons. While Botswana has high levels of solar irradiance, the amount of installed solar home
systems is shockingly low. There are distinct ways to harvest the solar energy from the sun being
Solar thermal uses the heat of the sun to warm up water so that it can be used for showers and other
hot-water applications like washing. Absorbed solar power focusses the energy of sunlight by shaving
mirror onto a focal point. The absorbed sunlight heats a fluid, which is used to produce steam, which
then turns a turbine to produce electricity. Photovoltaic generation of energy using solar panels is the
most commonly used and most promising approach to tap into the sun’s energy. Its application is
rising exponentially in many countries and it signifies one of the most significant resources of
renewable energy [1]. Solar energy has excessive potential in space heating for buildings, water
heating etc. due to its low-grade energy features and is the most important substitute to fossil fuels.
Solar systems with viable design and installation have very short settlement periods and meet the
energy mandate very effectively. Every location on earth collects sunlight at least part of the year. The
quantity of solar radiation that reaches any one "spot" on the earth's surface differs according to
topographical location, time of the day, period, local landscape and local weather. The form of the
earth makes the sun to strike its surface at different viewpoints ranging from 0º [2].
STATEMENT OF THE PROBLEM
Through observation and documented records, it was found that most people use power in their homes
to run their appliances and to heat water at their homes. On that opinion a research was done to
suggest the design of a Solar Home System which will help limit the problem of using electricity in
homes to run the appliances and even heat water as it will mean removed energy costs, reduced
greenhouse emission of gases and also reduced power cuts due to overload. A working and tested
solar home system can help a long way in resolving problems of those using electricity and those who
don’t have electricity at all.
PURPOSE/ OBJECTIVES OF THE RESEARCH PROJECT
The purpose of this research project is to design a solar home system that will help show people the
importance of switching to solar power as solar home system has many advantages.
SIGNIFICANCE OF THE PROJECT
6
The significance of this project is to show how a solar home system is designed and how it works and
to show that it is important to use solar home system as the sun provides lots of energy that it will ever
be needed and it eliminates electricity bills and also helps get rid of the problem of greenhouse gasses.
SCOPE OF THE PROJECT
A solar home system is to be considered and tested. The term Solar Home System and its
acronym SHS, refers to a stand-alone system, appropriate for residential applications, such as home
appliances, lighting, computers and water pumps. Usually, the SHS is low power, less than 100 W.
The SHS is usually designed and sized to source DC and/or AC electrical appliances. It contains PV
modules linked to a PV charge controller, stand-alone inverter and battery system. The produced DC
power is stored in the battery and changed to AC power for supplying to AC loads;[3]
Figure 1: Solar Home System for AC loads [3]
PROJECT PLAN
7
PROJECT NAME
PROJECT MANAGER
Solar Home System
Kabo Dikatholo
START DATE
END DATE
OVERALL PROGRESS
TASK
Pre-requisites
Project proposal
Project consulation
Initiation
Project Introduction
Project consulation
Literature Review
library research
Project consulation
Development
Design
Project consulation
Research
Project consulation
Results analysis
Project consulation
Results discussion and interpretation
Operations
Project Submission
Project Presentation
09-Sep
03-Dec
20%
OWNER
START
END
DURATION(DAYS)
STATUS
K.Dikatholo
K.Dikatholo
09-Sep
14-Sep
13-Sep
14-Sep
4 complete
0 complete
K.Dikatholo
K.Dikatholo
K.Dikatholo
K.Dikatholo
K.Dikatholo
15-Sep
21-Sep
22-Sep
29-Sep
05-Oct
20-Sep
21-Sep
28-Sep
04-Oct
05-Oct
5 complete
0 complete
6 complete
5 complete
0 complete
K.Dikatholo
K.Dikatholo
K.Dikatholo
K.Dikatholo
K.Dikatholo
K.Dikatholo
K.Dikatholo
06-Oct
12-Oct
13-Oct
16-Nov
17-Nov
23-Nov
24-Nov
11-Oct
12-Oct
15-Nov
16-Nov
22-Nov
23-Nov
30-Nov
5 complete
0 complete
33 complete
0 complete
5 complete
0 complete
6 complete
K.Dikatholo
K.Dikatholo
01-Dec
03-Dec
01-Dec
03-Dec
0 complete
0
LIMITATIONS OF THE PROJECT
The time to do the research project was not enough.
The global pandemic made it hard to do the research project.
CHAPTER TWO: REVIEW OF RELATED LITERATURE
8
INTRODUCTION
Solar energy has experienced remarkable growth in current years due to both technological
developments resulting in cost reductions and government strategies supportive of renewable energy
development and consumption. The cost of solar energy has deteriorated quickly in the recent past, it
still remains much higher than the cost of conventional energy technologies. Like other renewable
energy technologies, solar energy profits from fiscal and regulatory incentives and mandates,
including tax credits and exemptions, feeding-tariff, special interest rates, renewable portfolio
standards and voluntary green power plans in many countries. Potential increase of carbon credit
markets also would deliver additional incentives to solar energy distribution; however, the scale of
incentives provided by the existing carbon market tools, like the Clean Development Mechanism of
the Kyoto Protocol, is limited. In spite of the huge technical potential, development and large-scale,
market-driven deployment of solar energy technologies world-wide still has to overcome a number of
practical and financial barriers. Unless these barriers are overcome, keeping and increasing power
supplies from solar energy will need continuation of potentially costly policy supports. [4]
MAIN BODY OF THE CHAPTER
Here’s how PV power works: A solar panel—or more correctly, solar module—is made up of solar
cells, each comprising thin layers of silicon, the same material used generally in the computer
industry. Silicon has semi-conductive properties. Sunlight is absorbed by the cells in the unit,
initiating an electron exchange between the layers of silicon to yield electrical power. Connecting the
module with wires generates an electrical circuit and a means for harnessing this electrical activity.
Solar modules can be installed in a series to create a solar “array.” The size of an array, as well as the
quality of the modules’ semiconductor material, determines its power output. [5]
The electricity produced by solar cells is DC, or direct current, which is what most batteries produce
(and what battery-powered devices run on). Household electrical systems and standard appliances run
on AC, or alternating current, electricity. Powering these items requires an inverter that converts the
DC power from the modules (or batteries) to AC power. It’s all the same to your appliances, and they
run just as well on solar-generated power as on standard utility power. Converting from DC to AC
isn’t always necessary or ideal. Many small PV systems, such as those supplying a workshop or
greenhouse, as well as portable systems used on boats and recreational vehicles, are set up for DC
power and include DC appliances and devices. Even some household systems employ highly efficient
DC appliances that don’t require conversion. [5]
In off-grid solar systems, there is no connection to the electrical grid. In Botswana, such
installations are typically found on homes, on farms, in villages, or at tourist lodges in remote
9
areas. Because these systems cannot use the grid for back-up electricity supply, they usually
incorporate batteries so that any excess energy, produced during the day can be stored for use
during evening hours. Off-grid installations are sometimes combined with other means of
electricity generation, such as diesel generators, that can provide backup power during cloudy
conditions or when the batteries are depleted. These are referred to as hybrid systems. Off-grid
systems in Botswana range from small single-panel systems (100 to 200 W), providing
a small amount of power for a few lights or mobile phone charging, to multi-panel systems
powering a home/farm or a borehole pump (1 to 20 kW), to large systems powering tourist
lodges in the Okavango Delta (20 to 100 kW). [1]
Solar Home System are stand-alone photovoltaic systems that offer a cost-effective mode of
supplying amenity power for lighting and appliances to remote off-grid households. In rural areas,
that are not connected to the grid, SHS can be used to meet a household's energy demand fulfilling
basic electric needs. Globally SHS provide power to hundreds of thousands of households in remote
locations where electrification by the grid is not feasible. SHS usually operate at a rated voltage of
12V Direct Current (DC) and provide power for low power DC appliances such as lights, radios and
small TVs for about three to five hours a day. Furthermore, they use appliances such as cables,
switches, mounts, and structural parts and power conditioners / inverters, which change 12/ 24 V
power to 240VAC power for larger appliances. SHS are best used with efficient appliances so as to
limit the size of the array. A SHS typically includes one or more PV modules consisting of solar cells,
a charge controller which distributes power and protects the batteries and appliances from damage and
at least one battery to store energy for use when the sun is not shining. They contribute to the
improvement of the standard of living by: reducing indoor air pollution and therefore improving
health as they replace kerosene lamps, providing lighting for home study, giving the possibility of
working at night and facilitating the access to information and communication (radio, TV, mobile
phone charging). Before installing a photovoltaic (PV) SHS, its size has to be calculated according to
different assumptions, such as measurement of solar radiation, solar insolation and power demand. [6]
CHAPTER 3: METHODOLOGY
10
DESIGN
Solar panels are the most noticeable element of a residential solar electric system. The solar panels are
linked outside the home, naturally on the roof and change sunlight into electricity. The photovoltaic
effect is the method of changing sunlight into electricity. This process gives solar panels their
additional name, PV panels. Solar panels are given output ratings in watts. This rating is the
maximum produced by the panel in perfect conditions. Output per panel is between 10 and 300 watts,
with 100 watts being a common configuration. [7]
The solar home system is made up of the following components:
Solar panels
Solar panels are the most noticeable component of a residential solar electric system. The solar panels
are installed outside the home, characteristically on the roof and convert sunlight into electricity. [7]
Solar Array Mounting Racks
Solar panels are joined into arrays and commonly mounted in one of three ways: on roofs; on poles in
free standing arrays; or directly on the ground. Roof mounted systems are the most common and may
be required by zoning ordinances. This approach is aesthetic and efficient. The main drawback of roof
mounting is maintenance. For high roofs, clearing snow or repairing the systems can be an issue.
Panels do not usually require much maintenance, however. Free standing, pole mounted arrays can be
set at height that makes maintenance easy. The advantage of easy maintenance must be weighed
against the additional space required for the arrays. Ground systems are low and simple, but cannot be
used in areas with regular accumulations of snow. Space is also a consideration with these array
mounts. Regardless of where you mount the arrays, mounts are either fixed or tracking. Fixed mounts
are present for height and angle and do not move. Since the angle of the sun changes throughout the
year, the height and angle of fixed mount arrays are a compromise that trades optimum angle for a
less expensive, less complex installation. Tracking arrays move with the sun. Tracking array move
east to west with the sun and adjust their angle to maintain the optimum as the sun moves. [7]
Array DC Disconnect
The Array DC disconnect is used to disconnect the solar arrays from the home for maintenance. It is
called a DC disconnect because the solar arrays produce DC (direct current) power.[7]
Inverter
Solar panels and batteries produce DC (direct current) power. Standard home appliances use AC
(alternating current). An inverter converts the DC power produced by the solar panels and batteries to
the AC power required by appliances.[7]
Battery Pack
11
Solar power systems produce electricity during the daytime, when the sun is shining. Your home
demands electricity at night and on cloudy days – when the sun isn’t shining. To offset this mismatch,
batteries can be added to the system.[7]
Power Meter, Utility Meter, Kilowatt Meter
For systems that maintain a tie to the utility grid, the power meter measures the amount of power used
from the grid. In systems designed to sell power the utility, the power meter also measures the amount
of power the solar system sends to the grid.[7]
Backup Generator
For systems that are not tied to the utility grid, a backup generator is used to provide power during
periods of low system output due to poor weather or high household demand. Homeowners concerned
with the environmental impact of generators can install a generator that runs on alternative fuel such
as biodiesel, rather than gasoline.[7]
Breaker Panel, AC Panel, Circuit Breaker Panel
The breaker panel is where the power source is joined to the electrical circuits in your home. A
circuit is a continuous route of connected wire that joins together outlets and lights in the electric
system. For each circuit there is a circuit breaker. Circuit breakers prevent the appliances on a circuit
from drawing too much electricity and causing a fire hazard. When the appliances on a circuit demand
too much electricity, the circuit breaker will switch off or trip, interrupting the flow of electricity.[7]
Charge Controller
The charge controller – also known as charge regulator – maintains the proper charging voltage for
system batteries. Batteries can be overcharged, if fed continuous voltage. The charge controller
regulates the voltage, preventing overcharging and allowing charging when required.[7]
Load
The load in a solar home system comprises of the appliances connected or used in the household like
the fridge, the lights, the Tv, fan, iron and other electronic appliances that can be used.
12
Figure 2: A small DC Solar Home System
13
Figure 3: A solar home system [9]
14
APPLICATIONS OF SOLAR
•
•
•
•
•
•
•
Solar lighting
Solar heating
Solar ventilation
Solar water heating
Portable solar
Solar transportation
Solar electricity
Constraints and problems
The majority of the recorded technical problems appear to be minor problems which could easily be
attended to by the local maintenance person if PV spares were made accessible at the local level.
15
CHAPTER FOUR: PRESENTATION AND ANALYSIS OF RESULTS
A research was done in the village of Kanye from a solar home system. Table 1 shows the electrical
appliances, their power ratings, time they take operating and the power per day.
Table 1: RESULTS OF ELECTRICAL APPLIANCES AND THEIR POWER RATING
APPLIANCES
POWER
HOURS USED PER DAY
Wh PER DAY
USE(WATTS)
Iron
1100
0.25
280
LED Light Bulb
10
5
50
Refrigerator
180
24
4320
Microwave
1200
0.5
600
Cooking stove top
1500
2
3000
Cell Phone
5
3
15
Laptop
60
6
360
LCD TV 42inch
120
5
600
Air conditioner
1000
3
3000
Clothes Washer
500
0.25
130
Coffee maker
800
0.33
260
Hair Dryer
1500
0.1666
250
Vacuum
1400
0.1666
230
Charger
16
WATT PER DAY AGAINST TIME
5000
4320
4500
4000
3500
Wh per day
3000
3000
3000
2500
2000
1500
1000
600
600
360
280
500
50
130
15
260 250 230
0
0
2
4
6
8
10
12
14
Time
SOLAR PANEL AND BATTERY CALCULATIONS
The total power = 1100+10+180+1200+1500+5+60+120+1000+500+800+1500+1400
Total power = 9375W
Total load in a day = 280+50+4320+600+3000+15+360+600+3000+130+260+250+230
Total load in a day = 13 095Wh per day
Total solar panels energy= 13095 * 1.3= 17 023.5Wh/ day
(1.3 is the energy lost in the system[8])
Total WP of PV capacity=17 023.5/3.4= 5006Wp
(Panel generation factor is 3.4 [8])
(The panels you would use in a residential setting typically range from 275 to 350 watts per
panel[10].)
5006 / 335W= 14 panels
15 panels of 335W have been used in this household.
17
The other step is to determine the battery bank size. While there is a thrust to adopt and utilize Li-Ion
battery, the lead-acid battery still holds a substantial chunk of the market and hence they are wellthought-out here. The currently in use battery comes with 12V, 100/120 Ah capacity with maximum
Depth of Discharge (DoD) (DoD means what is the maximum capacity of the battery which could be
used before recharging it) of 70%. Generally, this is the recommended range, depending on the
power: Up to 0.5 kW: 12 V,0.5 – 2 kW: 24 V,2 - 10 kW: 48 V, above 10 kW: 96 V, of course, the
limits are not strict.[11]
The charge capacity of battery bank = Energy required/ System voltage[11].
The capacity of the battery bank= 13 095/48= 272Ah
The number of batteries to produce such charge is
Number of batteries required in parallel= 272/ (120*0.7)= 3.23 (approximately 3)
Number of batteries in series= System voltage /Voltage of battery= 48/13= 3.7 (approximately 4)
This means the battery bank must have been 3 in parallel and 4 in series to sustain the load.
18
CHAPTER FIVE: DISCUSSION AND INTERPRETATION OF RESULTS
From table 1 it is clear of the capacities of the residential appliances with the hours they operate for
and the power they consume in a day. From the table number of the solar panels for the household
have been calculated and it was made easy by the fact that the total number of power consumption
was measured and calculated and its 13 095Wh per day. It was also calculated of how many solar
panels could be running all these appliances and the as it’s a 335W solar panel the calculations proved
the number of those panels is 15. In that case, as battery backup is required to store power that runs
the appliances, the battery number and voltage was calculated which the capacity of a single battery
proved to be approximately 273Ah with approximately 3 batteries in parallel and 4 batteries in series
to run the household.
This researched has proved how a residential place can be run by a solar power system and has shown
the tools needed to run a solar home system, which shows how its not much different from using the
electricity generated by coal and it has more advantages that comes with it.
19
REFERENCES
1] A Multidisciplinary Examination of Solar Power in Botswana[online]. Available at
https://www.researchgate.net/publication/311993872_A_Multidisciplinary_Examination_of_Solar_Po
wer_in_Botswana [Accessed on 29 November 2020]
2] Design, Modelling and Experimental Investigation of an Economic Domestic STHW System Using
T*Sol® Simulation in Botswana[online]. Available at https://www.matecconferences.org/articles/matecconf/pdf/2018/31/matecconf_icdams2018_06004.pdf [ Accessed 29
November 2020]
3] Solar Home Systems[online]. Available at https://www.sciencedirect.com/topics/engineering/solarhome-systems [Accessed on 29 November 2020]
4] A Review of Solar Energy: Markets, Economics and Policies [online]. Available at
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1945636 [Accessed 29 November 2020]
5] MLA (Modern Language Assoc.)
Smith, Eric W., et al. DIY Solar Projects : Small Projects to Whole-Home Systems: Tap Into the Sun.
Vol. Updated edition, Cool Springs Press, 2016.
APA (American Psychological Assoc.)
Smith, E. W., Schmidt, P., & Wanek, T. (2016). DIY Solar Projects : Small Projects to Whole-home
Systems: Tap Into the Sun: Vol. Updated edition. Cool Springs Press.
Available at
http://web.a.ebscohost.com/ehost/ebookviewer/ebook/bmxlYmtfXzE0NDk2MTlfX0FO0?sid=56b51e
7a-51e5-41c0-b777-b8a217f5049e@sdc-v-sessmgr02&vid=1&format=EB&rid=1 [Accessed 29
November 2020]
6] Energypedia [online]. Available at
https://energypedia.info/wiki/Solar_Home_Systems_(SHS)#Solar_Home_Systems_in_Peru
[Accessed 29 November 2020]
7] Components of A Residential Solar Electric System[online]. Available at
https://www.cleanenergyauthority.com/solar-energy-resources/components-of-a-residential-solarelectric-system [Accessed on 30 November 2020]
8] A Remarkable Cost Effective Solar Home System in Rural Area of Bangladesh[online]. Available
at
https://www.researchgate.net/publication/324199648_A_Remarkable_Cost_Effective_Solar_Home_S
ystem_in_Rural_Area_of_Bangladesh [Accessed 30 November 2020]
20
9] Eco friendly solutions[online]. Available at https://eco-friendly-india-solutions.com/ecoproducts/1kw-solar-power-system/ [Accessed on 30 November 2020]
10] An Unbound Renewable Energy Company [online]. Available at
https://unboundsolar.com/blog/how-many-solar-panels-do-i-need [Accessed 30 November 2020]
11] Quora [online]. Available at https://www.quora.com/How-many-solar-panels-and-batteries-areneeded-for-a-3kW-solar-system [Accessed on 30 November 2020]
21