COST-BENEFIT ANALYSIS OF SOLAR POWER USAGE IN
RESIDENTIAL BUILDINGS IN AKURE
ADEWUMI, Ayomikun Solomon
Department of Architecture
Federal University of Technology, Akure
M.Tech 1
Course: Applied Climatology (ARC810)
Course Lecturer: Prof. O.O Ogunsote
Matriculation Number: ARC/05/5577
Abstract
With the persistent state of epileptic power supply in Nigeria coupled with emission of
greenhouse gases, the need to incorporate an alternative means for energy supply can never be
overemphasized in such a time as this. In considering an alternative therefore, one should opt
for one that is clean, environmentally friendly, readily available and renewable with the aim of
conforming to the concept of sustainable development and going green. The only green
alternative that has gained prominence in recent years is the solar power usage which has
found wide application in generating thermal and electrical energies. Other alternatives are
wind and geothermal energies. Considering some determining factors, this paper aims to relate
the cost of solar power usage in residential homes to the benefits it offers in a cost benefit
analysis using Akure- a ‘sun city’ in southwestern Nigeria as the study area. Such benefits
include: Environmental friendliness, reduction in global warming, easy installation, inexpensive
on the long term and low maintenance e.t.c.
Keywords: alternative means, cost-benefit analysis, energy supply, renewable, solar power,
sustainable development
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
1.0
INTRODUCTION
The sunlight that reaches the earth comprises of up to 50% visible light, 45% infrared
radiation, small amount of ultraviolet and other forms of electromagnetic radiation
(Encyclopædia Britannica, 2009a). This radiation has a strong potential of either been converted
to thermal energy or electrical energy. Encyclopaedia (2009b) defined thermal energy as the
internal energy present in a system in a state of thermodynamics equilibrium by virtue of its
temperature. The flat plate collectors and the concentrating collectors are the two main types
of devices used in capturing and converting solar energy into thermal energy.
Solar energy can be converted directly to electricity by solar cells. It basically works on
the principle that in such cells, a small electric voltage is generated when light strikes the
junction between a metal and a semi-conductor or the junction between two different
semiconductors. The potential of the solar energy is enormous giving an account of generating
almost 200,000 times the world’s daily electricity if only it can be utilized. Further research
submitted that the sun generates more than 10, 000 times the amount of energy the entire
world consumes annually (Green Living Ideas, 2011). Unfortunately, though the solar energy
itself is free, the high cost of its collection, conversion and storage all hinders its exploitation.
Generating electricity from the sun is known for many centuries ago and can be traced
back to ancient Greeks and Romans who used the Sun’s capacity to light and heat indoor spaces
and ending at present times when solar technology has made huge achievements and is ready
not only to compete with other well known energy sources but already even to replace them.
In the 19th century, scientists were attracted and intrigued by solar energy possibilities. From
then till now there have been huge inventions in solar technology sector which led to
spectacular development in this sector. Indeed, some very important inventions were made.
A good example was Albert Einstein who did a research on the photoelectric effect (a
phenomenon central to the generation of electricity through solar cells). William Grylls Adams
also revealed that when light was shined upon selenium, the material shed electrons, thereby
creating electricity. Gerald Pearson, Daryl Chapin and Calvin Fuller invented the first silicon
solar cell capable of generating a measurable electric current in 1953. This invention was
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
announced and reported to be as “the beginning of a new era”, leading eventually to the
realization of harnessing the almost boundless and limitless energy of the sun for the uses of
civilization. However, in 1956 the solar photovoltaic panels (PV) were still far from economically
practical. In comparison, electricity from solar cells ran at about $300 per watt while today
market rates are around $5 for a watt of solar PV (Proposed Basic Concept of Energy Chain by
the World Energy Congress, 2004). For achieving such price difference, massive investment in
subsidies and research were done. Lately, in 2002, Japan installed 25,000 solar rooftops and
such large PV orders are creating economies of scale, as a result steadily lowering costs. Worthy
of note is that the PV market is currently growing at 30 percent per year and that gives a
promise of continually decreasing costs.
Nigeria as a country is rich with energy resources such as petroleum, natural gas, coal,
tar sand, and biomass. The country consumes a large amount of liquefied petroleum gas, motor
spirits, kerosene, diesel oil, fuel oil, and gas oil. All of these mentioned energy sources give huge
impact to climate change problems with lots of green-house gasses emissions as well as a rise in
many environmental problems in general. From the perspective of renewable energy therefore,
the country has a massive potential for developing and implementing energy sources such as:
solar, hydro, biomass, and wind energy.
Knowing that Nigeria has an annual average daily solar radiation of about 5.25
kWh/m²/day, varying between 3.5 kWh/m²/day at the coastal areas and 7.0 kWh/m²/day at the
northern boundary, and average sunshine hours all over the country is about 6.5 hours (P. Lloyd
and E. Visagie, 2007) can give us an impression that implementing solar energy strategy is a
great opportunity for Nigeria to get renewable energy at low cost as well as minimize
dependence from fossil fuels; and finally solar energy would give an opportunity to implement
infrastructure where before it seemed to be too hard or too expensive. This paper thus focuses
on the cost-benefit analysis of solar power usage in Residential buildings in Akure.
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
2.0
THEORETICAL CONCEPTS
2.1
SOLAR POWER USAGE IN RESIDENTIAL BUILDING
In discussing solar usage in residential premises, two options that readily come to mind
are application for thermal (when a heat pipe are arranged to heat up hot water) and solar
home electricity. By comparison, the solar thermal is more efficient as regards storing and
conserving of energy for future use. Also the largest draw on power use that most family have
after running the refrigerator is hot water for showers and cleaning. A solar power residential
system is a bit technical as necessary information may need to be taken on the actual electricity
usage and the orientation of the house as the system requires a south facing solar panel system
where sunlight can be trapped and converted to electricity (Solar Power Buzz, 2011). This
however depends on how the house was constructed as this may or may not be feasible as the
more the radiation received during the day, the more efficient it is when the need arises.
Required for the set up aside the photovoltaic rays are a power inverter (to convert the
direct current to alternating current), charge controllers and batteries to store power for future
use.
Figure 2.1: Figure showing a solar power usage set up
Source: Karolis et al (2008)
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
2.2
SOLAR PANELS
These are devices that receive light from the sun and convert it to energy suitable for
home use (Green living ideas, 2011). They are located on the roof of the house and connected
to the heating system. Solar panels serve two major functions in residential buildings which are
to heat water and produce electricity. Solar panels designed to heat water are also known as
thermal solar system while electricity producing panels are called photovoltaic systems.
The method of operation depends on what purpose the solar panels are meant to serve
i.e. either as solar water heating or for electricity. A solar water heating system usually contains
a ‘collector’ to absorb solar radiation and turn it into heat. A heat-conducting liquid then carries
the heat from the collector to the hot water tank.
In an electricity-producing system however, a positively charged layer of silicon is placed
against a negatively charged layer of silicon forming a field of electrical charges to pass through.
The sunlight as it shines on the panel creates these electric charges. A conductive metal is made
available which concentrates the charge into an electric current which can power household
appliances.
2.3
CHARGE CONTROLLERS
These are sold to consumers as separate devices often in conjunction with solar
generators for uses such as RV, boat and off-the-grid home battery storage systems (Wikipedia,
2011a). Charge controllers are also called solar regulators in solar application. They function
majorly to disable further current flow into batteries when they are full. Simple charge
controllers stop charging a battery when they exceed high voltage level and re-enable charging
when battery voltage drops below that level.
2.4
INVERTERS
An inverter is an electrical device that converts direct current (D.C) to alternating
current (A.C). This converted A.C can be at any required voltage and frequency with the use of
appropriate transformers, switching and control circuits (Wikipedia, 2011c).
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
A power inverter is a complex device that converts direct current (D.C) power from solar
charged battery into alternating current (A.C) form (Wikipedia, 2011d). It has found wide
application in homes and other domestic situations. A well manufactured inverter is
characterized with high efficiency at all power levels, ruggedness to accommodate multiple
environment, stable (i.e. will not overheat) and will provide the required power and wattage to
operate small appliances (Wal Solar Corporation, 2011a).
3.0
RESEARCH METHODOLOGY
For the purpose of this study, information was gathered both from the primary and
secondary sources of information with more of the information obtained from the secondary
sources. The secondary sources include: existing records and documentation in books, journals,
web materials and other literatures. Information obtained was analyzed using the cost-benefit
analysis
The cost-benefit analysis
The cost-benefit analysis (CBA) also known as benefit cost analysis is an economic
decision-making approach used in the assessment of whether a proposal is worth doing or to
opt for possible alternatives (Wikipedia, 2011b). It basically involves comparing the total
expected benefits to see whether the benefits out weight the cost and by how much. Benefits
and costs are therefore expressed in money terms and are adjustment for the time value of
money.
4.0
THE STUDY AREA
Akure (+7° 15’ N, +5° 11’24’’ E), is the capital city of Ondo State, South-West Nigeria.
Because of its equatorial location and the climatic condition, solar radiation is appreciable for a
good part of the year. The raw data of daily sunshine hours for the period 2001 to 2007 were
obtained from the Akure Airport Meteorological Station and tabulated.
From the tabulation, a statistical mean daily sunshine hour was estimated at 5.21 hours
as shown below. Table 4.0 reveals average highest amplitude of 7.29 hours per day in
November and 2.9 hours in August.
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
Table 4.0: Annual Average Sunshine Hours in Akure
Month
2001
2002
2003
2004
2005
2006
2007
January
6.20
5.40
5.80
4.50
February
6.90
6.40
7.20
4.90
March
6.00
3.70
5.60
6.60
April
6.10
5.00
6.00
5.20
May
6.10
5.60
5.60
6.20
June
5.50
4.60
4.90
5.10
July
3.00
2.80
2.70
4.30
August
2.10
2.30
2.90
4.70
September 3.80
2.90
3.40
3.50
October
4.50
5.50
5.90
5.60
November 6.80
6.60
6.60
8.30
December 6.00
5.00
4.70
5.50
Year Av.
5.25
4.65
5.11
5.37
Source: Akure Meteorological Station (2011)
7.10
7.70
6.00
5.70
6.20
5.90
3.00
2.70
3.40
4.90
7.60
4.80
5.42
7.20
7.90
6.00
5.70
6.20
5.90
3.00
2.70
3.40
4.80
7.60
4.80
5.43
6.80
5.70
5.30
5.50
6.10
5.70
4.40
2.90
3.50
4.70
7.50
4.70
5.23
Month
Average
6.14
6.67
5.60
5.60
6.00
5.37
3.31
2.90
3.41
5.13
7.29
5.07
5.21
There are two distinct seasons: the rainy season which starts in April and peaks in June
through September and the dry season which begins in November and lasts till April. A large
percentage of her estimated populations of about 350,000 are mainly farmers, traders and
artisans (Aribigbola, 2009).
5.0
FINDINGS AND DISCUSSION
5.1
ESTIMATE COST OF SOLAR POWER USAGE
Melodi O.A and Famakin S.R (2011) in their research on the Assessment of Solar PV-Grid
Parity in Akure came up with estimates on the cost of using solar PV in which the result
obtained will be used in this section of the paper as highlighted below:
The research was carried out on a hypothetical consumer wishing to run the following
domestic appliances on a solar PV system for the average sunshine period of 5.21 hours
available in the study area was considered as follows:
I.
2 X 50W Fans
II.
1 X 75W Fridge
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
III.
1 X 100W Television
IV.
1 X 80W Music Set
The capacity of the equipment needed may be estimated as follows:
Inverter output size ≥ sum of the capacities of appliances X Load diversity factor
Mathematically recall as:
where Po.inv is the inverter output size, Papp is appliance capacity, dl is the diversity factor, n is
number of appliances. Using the information given above and taking dl=1,
Po.inv ≥ ((2 X50W) + (75W) + (100W) + (80))
Po.inv ≥ 335W
Since efficiency = Output/ Input, let inverter efficiency= 95% (Sunsteams, 2011)
Then, input into inverter
output / efficiency= 355/0.95= 373.68W
Since the input into the inverter= output from solar PV array
A system of 3 X 125W Solar PV panels amounting to 375W may be deployed. If losses in
inverter are limited to 25W, a 400W inverter may be selected for the duty.
It is also important to consider the cost of other solar equipment. The table below thus shows
the prices of these equipments as of July 2010
Table5.1a: Solar equipment price index as of July 2010
S/No Equipment
Price/unit output (USD) Sampled Manufacturers
1
Solar PV modules
4.18/Watt
Matrix photowatt, Unisolar, Sunware, Isofoton,
Sanyosolar, Sharp Corporation, Suntech Power,
Kaneka Corporation, Sunpower
2
Inverter
0.715/Watt
Xantrex Technology inc, Solarix, Studer, Soltek,
Powersine, Sharp Electronics, Powerpro
3
Battery
0.207/Watt hour
Varta AG, Exide, Optima, Northern Battery,
Dyno, Douglas, Concorde, Trojan Battery
4
Charge Controllers 5.87/Amp
Morningstar Corporation, Xantrex, Geosolar,
Vario, Outback power, Lyncom, Plasmatronics,
ICP solar
Source: Solarbuzz (2011)
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
Table5.1b: Bill of estimate for the installation of 2Kw Solar PV array.
S/No
1
2
3
Description
Unit
Solar power
W
Inverter capacity
W
Solar plates supporting
Lot
structure
4
Cabling and terminations
Lot
5
Labour
Lot
TOTAL
Source: Melodi O.A and Famakin S.R (2011)
Quantity
375
400
1
Rate ($)
4.18
0.715
100
Amount ($)
1, 567.50
286.00
100.00
1
1
150
150
150.00
150
2,253.50
Further research work was carried out in other to predict the future cost of solar power
usage in Akure. The result obtained is as shown in the table below:
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
Table5.1c: Comparison of Solar PV-PHCN Energy Cost Per Unit in Akure
S/No
Time (Years
Solar PV
Solar PV
Annual
Energy Produced (kWh)
Degradation
0.71%/Yr
Less Annual Cumulative
Degradation Energy
1
2000
2
2001
3
2002
4
2003
5
2004
6
2005
7
2006
8
2007
9
2008
10
2009
11
2010
12
2011
4.79
675.09
13
2012
4.76
670.30
14
2013
4.73
665.57
15
2014
4.69
660.84
16
2015
4.66
656.12
17
2016
4.63
651.47
18
2017
4.59
646.87
19
2018
4.56
642.28
20
2019
4.53
637.69
21
2020
4.50
633.16
22
2021
4.46
628.65
23
2022
4.43
624.19
Source: Melodi A.O and Famakin S.R (2011)
5.2
675.09
1345.39
2010.96
2671.80
3327.92
3979.39
4626.26
5268.54
5906.23
6539.39
7168.04
7792.23
Solar PV
Unit Cost
(N)
500.71
251.2005
168.09
126.52
101.57
84.94
73.07
64.16
57.23
51.69
47.16
43.38
Grid
Cost/Unit
2.60
2.60
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.40
5.90
7.30
7.40
COST ANALYSIS
From the above table and former findings, the following deductions can be made:
I.
Grid supply (that is utility supply from P.H.C.N) remains cheaper than Solar PV by
N149.45 and N97.55/kWh in the short and medium term respectively.
II.
On the long term, convergence is reached, parity is attained and solar electricity from
that point becomes cheaper than grid supply.
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
III.
Also, it is only on the long term that parity i.e. point at which alternative means of
generating electricity becomes equal in cost.
IV.
The unit cost of the Solar PV continues to tend towards zero within the span of its useful
life.
5.3
BENEFITS OF SOLAR POWER USAGE IN RESIDENTIAL HOMES
Some benefits of solar power usage in residential homes are as stated below:
5.3.1 DEPENDABILITY
Photovoltaic cells were originally developed for use in space where repair obviously is
expensive if not impossible. Till date photovoltaic still power nearly every satellite circling the
earth because it operates reliably for long periods of time with little or maintenance. The
system aside from been maintenance free, it also has the ability of providing electricity for
25years-40years. In fact, most solar panels have 25years manufacturer warranty on the
production.
5.3.2 REDUCTION OF GLOBAL WARMING
Incorporating solar energy in homes reduces the consumption of fossil fuels, which
helps to reduce pollution and green house gases emission. Researchers discovered that a small
solar electric system has a significant environmental impact. In fact 2.5KW solar system reduces
carbon dioxide emissions by an amount similar to that which would occur by planting 1 acre of
trees or the emission by a passenger car driving 7,800 miles per year (Green Living Ideas, 2011).
5.3.3 EXEMPTION FROM FAST CLIMBING ELECTRIC RATES
Solar power aside that it brings about self independence in generating power, it also
exempts one from the utility rate increase. The Nigeria situation is alarming with the gradual
and persistent increase in electricity tariffs. In fact, study shows that electricity rates will
continue to climb faster than inflation.
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
5.3.4 CHEAPER THAN THE UTILITY POWER
Solar power system can be akin to preparing for up to 40years of power at a fraction of
the cost been currently paid. The cost/unit of energy paid is more than what is obtained in
solar. As rates increases in future years, this difference will increase leading to more concern as
regards savings over the life of a solar energy system.
Other Benefits Includes:
5.4

Environmental Friendliness

Self generation and saving money on utility bills

Easy Installation

Low Maintenance

Long lasting, safe and silent

Generation of clean and inflation proof electricity

Stability in price
COST-BENEFIT ANALYSIS
From the findings made so far, solar power usage economic benefit can be appreciated
on the long term basis but not on short and medium term basis. However there are
unquantifiable benefits that are derived on this short and medium term basis when the solar PV
is seen to be expensive. For example, how can one value the availability of a clean and inflation
proof electricity or cost the importance of a ‘green’ energy aside other benefits earlier
mentioned? It is worthwhile to note that at a point on the long term, cost per unit of electricity
will be at no tangible cost so far the source remains faithful.
Indeed considering the benefits to be derived on long term basis and the geometrical
increase in electricity tariff in the country as shown in figure 5.4, the solar power usage is still
more of economic benefit with more certainty and reliability attached to it.
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
Figure 5.4: Figure showing an increase in tariff rates in the utility supply
Source: PHCN (2011)
The pre-paid utility service also charge exorbitantly fixed charges which is almost 50% of
the total amount tendered as shown in the figure.
The table below further explains the cost and benefits of the solar PV in the short,
medium and long term (using table) with the associated benefits.
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
Table 5.4: Table showing gradual reduction in cost of solar PV with fixed benefits
Time (Years)
Unit Cost (N)
Benefits available
2011
500.71
Environmental friendliness, Reduction in global warming, self
2012
251.2005
generation, Easy installation, Low maintenance, Long lasting,
2013
168.09
safe and silent, Generation of clean, inflation proof
2022
47.16
electricity, Dependable e.t.c.
2023
43.38
2026
15.17
Source: Student’s field work (2011)
It should also be noted that the cost of solar PV can be reduced with a drop in the cost
of associated equipments which is not impossible i.e. cost of inverters, solar panels. Also
increase in the number of sunshine hours (if possible) and reduction in the value of degradation
factor which can be achieved through improved solar PV panel design and fabrication
technology will also be of help in reducing the cost.
6.0
RECOMMENDATIONS AND CONCLUSION
Home power generation has increased dramatically both in popularity and practicality
over the last few years and there is no doubt that the momentum will continue to increase
exponentially. With advancement in technology, the costs of building home power generations
have dropped significantly and it is now obvious and certain that affordable, practical solutions
to generating home energy are now available.
The economic benefits that solar power usage carry for a nation like ours are immense
as it does not only help in creating direct and indirect employment opportunities but also assist
on retaining the foreign exchange when the earnings from export are not spend on importation
of various spare parts of generators and e.t.c. Solar power usage will also help in the
development of the micro-enterprise since the enterprises despite the shortage can still
provide the services for its customers without losses.
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
Government should therefore embark on Solar PV promotion programmes and promote
the development of new solar PV technologies through enthusiastic support for research and
development works especially in relevant indigenous research institutes and tertiary
institutions.
In conclusion, this paper has analyzed the usage of cost implication of solar power usage
in residential buildings in Akure in a cost-benefit analysis submitting that the solar power usage
is indeed a good option to be considered for residential homes not minding the cost at the
outset if one can afford it but the benefits that it tends to offer on the long term basis.
7.0
REFERENCES
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COST-BENEFIT ANAYSIS OF SOLAR POWER USAGE IN RESIDENTIAL BUILDINGS IN AKURE
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