AMERICAN JOURNAL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
© 2012, Science Hu~, http://www.scihub.orglAJSIR
ISSN: 2153-649X doi: 1O.5251/ajsir.20 12.3.1.21.26
Demand management based design of residential solar power supply
system: a techno-economic evaluation
*V.O. Oladokun and S.A. Adeshiyan
Department of Industrial and Production Engineering University of Ibadan, Ibadan, Nigeria
*vo.oladokun@mail.ui.edu.ng; +2348033919050
ABSTRACT
With high solar radiation across Nigeria, solar power system can become a viable
solution to the Nigeria's electricity power crisis if the problem of high capital cost of solar
power supply system can be addressed. In this study the use of demand management
based design approach has been explored for reducing the capital cost of residential
solar power supply system. Utilities and energy demands of thirty randomly picked
homes in selected residential areas were studied The houses were classified into one,
two and three rooms' residential apartments. New energy efficient appliances that can
deliver the same or higher utility values as those already in use in these houses were
identified and proposed as replacement to cut energy demand. Cost analysis of
replacement with these energy star appliances was carried out. Solar system designs
and associated cost models were developed for both the existing demand system and
the proposed energy efficient demand system. For comparative analysis, appliances
replacement cost was factored into the associated solar system capital cost. The average
total energy demands were 1255W, 1785W, and 2185 for one, two, and three bedroom
flats respectively while equivalent demands for energy efficient system are 389W, 820W,
and 851W respectively. The cost of designing and installing a solar power with the
replaced appliances exhibits a significant reduction of 64.88%, 64.5% and 62.16% for the
one, two and three rooms residential set up respectively. We conclude that an integrated
demand management design approach is very useful in reducing the capital cost of
residential solar systems.
Keywords: Solar, Power, Demand management, Cost model, Residential
INTRODUCTION with solar thermal, against the UK with around
Meeting the power need of Nigeria has remained 2%; figure for Nigeria, though not available, is
a serious challenge to government and the crisis obviously negligible due to its relatively highacquisition cost. The economics of solar are
in the power sector has literally grounded the
nation's economy The use of solar power supply moderated by a balance between the high initialcost of a solar PV system and very low
system has been identified as a possible subsequent running costs compared to the low
renewable energy source for Nigeria and other
developing countries (Mpagalile et ai, 2006&2007; initial cost of, say, a diesel generator with veryhigh operation and maintenance costs. Generally
Arne, 2007). In addition solar power system is
environmentally friendly, safe, and has no gas installation cost is directly proportional to system
emissions nor generates noise (AI-Salaymeh et ai, power rating. The cost of installing a typical off-
2009) with strong support for its use from world grid PV system in a home ranges from $15,000 to$20,000 per kilowatt.
bank, UN and other international agencies
Karekezi and Kithyoma, 2002; Villavicencio, However the KWhr/day consumption of typical
2002). Though the operation cost of solar system residential home is a function of the efficiencies of
is low and attractive to consumers the high initial appliances and gadgets in use such that if proper
set up cost per Kwhr of solar powered system has consideration is given to appliances efficiencies at
limited or discouraged its use in realistic design stage the same or high level of utility can
residential applications Generally the utilization of be derived from less Kwhr requirement. This
solar panels for domestic applications differs demand management or Input-Output based
dramatically from county to country, with Germany design approach is the focus of this study.
having reached a level of 50% of domestic homes
/
UNIVERSITY OF IBADAN LIBRARY
Am. J. Sci. Ind. Res., 2012, 3(1): 21-26
Presently there are three basic steps in the design 2 as illustrated in figure1. While conceptually, we
of a PV system 1) Estimation of Load and Load are proposing an approach illustrated in figure2
profile, 2) Estimation of available solar radiation, for the design residential solar power supply
and 3) The design of Solar System based on 1and system.
Estimation of Load and Estimation of A vai lable
Load Profi Ie Solar Radiation
\ I
Design of Solar System
(Storage, PY modules,& other
Components)
Figl Output-based solar system design
Estimation of Load and Estimation of Available
Load Profi Ie Solar Radiation
, , ,,
,t , ,
~ , ,
,
,
k
Design of optimal consumption
(input) System
~
Design (output) Solar System (PV
modules, Battery Bank and other
Com nonents)
Fig 2 Input-Output (Demand Management) based solar power system design
The aim of this project is to provide a technical and conversion system which converts light into electric
economic assessment of a load input based current requiring no intervening heat engines using
residential solar system. The principal objectives are the photoelectric effect. The output of PV devices can
1) determine the basic appliances in a residential set range from micro watts to mega watts. Also because
up, and the power consumption of these appliances, solar radiation is intermittent there is always a need
2) identify alternative energy efficient home for storage systems so that it could make available
appliances as the basis for solar electricity system whenever it is needed. The storage system adopted
design, 3) carry out designs based on this energy is in fact critical to system performance and reliability
efficient system of appliances. (Teoman, 1992; Goswami et ai, 2000).
Solar Power supply System: an Overview: Solar The use of solar energy system cut across many
energy is utilized in buildings in two ways one, using areas applications such as desalination, crop drying,
solar systems to supply heat to warm up spaces lighting, and powering of small household appliances
through solar collector, and two using solar systems and its of areas applications will continue to expand
to generate electricity through Photovoltaic (PV) as cost drops (Eswaramoorthy and Shanmugam,
cells). Photovoltaic cell (PV) device is a direct 2006). There are many new technologies, such as
22
/
j
UNIVERSITY OF IBADAN LIBRARY
Am. J. Sci. Ind. Res., 2012, 3(1): 21-26
fiber optic photovoltaic and other types of Notation
photovoltaic cells, such as thin film, monocrystalline
silicon, polycrystalline silicon, and amorphous cells, i = the index identifying solar system components
as well as multiple types of concentrating solar power m = no of appliances in home to put on solar
that are being explored for the possibilities of
producing cheaper solar modules, However these j = index identifying household appliances j=1 ... m
technologies are still many years away from mass T, = The total cost of a solar power system
production ( Bingham, 2003).
C, = Capital cost of solar system
METHODOLOGY
The Residential Solar System Cost Model
Where Cs= Cost of solar panel (C'I ) + Cost of /~ = the replaceable appliances in the residential
inverter (Cn) + Cost of batteries (C\~)+ Cost of set up
charge controller (C'4) + Cost of installation Pi = Power rating appliance j
(C,\5 ) Sv= salvage value of replaced appliances
Ca = Energy efficient appliances replacement
Cost
...... (3)
Model development
So that Cost savings L'ITc is given by
11/
If P = total load = L PI L'lTe=01 -02 =k(~,-P..)-C" 'H(4)
1=1
Eqn 4 can be written in terms individual
Such that P is Pa= total load if solar system is appliances load as follows
designed for conventional appliances and
11/
Pis Pe= total load if system is designed for energy L'lTe= kCL (PoI-Pel) - C"
star appliances 1=1
k= capital cost per unit Watt of solar power And % savings is given by
system Then C, ' Capital cost of solar system is
given by
fII Where a positive % savings indicates that
Cs = kP = k"~" P expenses on appliances replacement is justifiableI
1=1 in the solar system design.
'0 ki' v Ca ...... (1) If the replaced appliances are resalable at some= salvage value Sv then 5 holds giving additional
When the supply system is designed for savings
conventional appliances with no need for L'lTe
appliances replacement then =01 -02 =k(~,-~,)-C" +S, (5)
...... (2)
Energy Audit
However when power system is designed for Energy audit of selected residential apartments
energy efficiency requiring the replacement of was carried out using structured questionnaires
existing appliances with energy star ones then and interviews Random sampling technique was
adopted to select 30 apartments covering three
23
UNIVERSITY OF IBADAN LIBRARY
Am. J. Sci. Ind. Res., 2012, 3(1): 21-26
main types of residential set ups; one room, two energy star rated appliances that can provide the
rooms, and three rooms residential set up. The required. utilities. The average total energy
study was carried out on the staff quarter of a demands were 1255W, 1785W, and 2185 for one,
University community based in South West two, and three bedroom flats respectively while
Nigeria to identify the appliances used for home equivalent demands for energy efficient system
utilities. Market survey of appliances was carried are 389W, 820W, and 851W respectively as
out in three major markets in Lagos Nigeria to shown in table 1
identify available alternative energy efficient or
Table1 Comparison of Energy Demand: Existing Vs Energy efficient Appliances
Utility Appliances in Energy Ave Apartment types
Use efficient daily
Appliances run One room Two rooms Three rooms
time No Pal Pel No Paj Pel No Pal Pej
Hrs Watts Watts Watts
Home 14 inches TV 14 inches 4 1 75 60 2 150 120 2 150 120
theatre (75) T.V (60)
Radio (210) Radio (50) 3 1 210 50 - - - - -
Computer Laptop (85) Laptop (64) 2 1 250 - 1 85 64 1 85 64
Desktop (250) Laptop (64) 2 64 - - -
Fan Fan (100) Fan (45) 2 2 200 90 3 300 135 3 300 135
DVD DVD (100) DVD (20) 2.5 1 100 20 1 100 20 1 100 20
Blending 150 ML 150 ML 6 - - - 1 300 200 1 300 200
Blender (300) Blender 200)
Refriger- 250 L Freezer 250 L 8 - - - - - - 1 90 87
ation (90) Freezer (87)
250 L fridge 250 L 8 - - - 1 150 87 - - -
(150) Freezer (87)
Lightning Type A Bulbs Energy star 6 7 420 105 - - - 8 800 120
(100) bulb (15)
Type B Bulbs Energy star 6 - - - 9 540 135 4 240 60
(60) bulb (15)
Florescent Energy star 8 - - - 4 160 60 3 120 45
lamps (40) bulb (15)
Total Loads Pa= Pe= Pa= Pe= Pa= Pe=
1255W 389W 820W 851W
1785W 2185W
'Note Heating/Ironing activities Will not be put on the solar system The residents can schedule heating, Ironing on the
Public power system.
Systems Design and Cost savings: Based on energy efficient systems were carried out for each
the result of the audit and survey studies of the apartment type
engineering designs of the solar power supply
systems were carried out for the three types of These designs were used to generate the cost
flats. The Watt-hour for each utility was estimated implications of solar systems based on existing
and summed to obtain the system Watt hour for appliances and energy efficient appliances. Figure
each of the apartment type. For the purpose of 3 is a typical model for the single apartment
comparison the designs for both convectional and design while detailed design is available in
24
UNIVERSITY OF IBADAN LIBRARY
Am. J. Sci. Ind. Res., 2012, 3(1): 21-26
Adeshiyan (2010). This empirical equivalence of 5 is as shown in table 2 for each of the three types
cost model represented by equations 2, 3, 4, and of apartment.
Table 2 Costing: Existing vs Energy star based system
Solar system component Existing Utility Energy efficient
Utility
Units Cost N Units Cost N
Single bedroom apartment
Solar Panel 10 800,000 2 160,000
Batteries 36 1,800,000 12 600,000
Inverter 1 80,000 1 50,000
Sub -total 2,680,000 810,000
Appliances replacement 0 131,150
Total 2,680,000 841,150
Two bedroom apartment
Solar Panel 20 1600000 3 240000
Batteries 60 3,000,000 24 1,200,000
Inverter 1 100,000 1 50,000
Sub -total 4,700,000 1,490,000
Appliances replacement 0 177,850
Total 4,700,000 1,667,850
Three bedroom apartment
Solar Panel 22 1,760,000 4 320,000
Batteries 60 3,000,000 24 1,200,000
Inverter 1 120,000 1 50,000
Sub -total 4880000 1,570,000
Appliances replacement 0 276,250
Total 4,880,000 1,846250
I PANEL I
1 1
12 I I 12 I I 12 I I 12 =200AH
l 12 I I 12 I I 12 I 12 1=200AH
~ n H'1'1fi ~ /. .e:
u x:rrr. RIE;::, r'JUU AH @ 4O¥1:1L TS)
I BATTERY BANK I
I I
~ ~
I Charge Controller I
~ ~
I INVERTER DISTRIBUTION I
Fig 3: Model diagram of P.V Subsystems for a typical one room residential set up.
UNIVERSITY OF IBADAN LIBRARY
Am. J. Sci. Ind. Res., 2012, 3(1): 21-26
CONCLUSIONS Thermoelectric Power Generator for Rural Residential
Energy Demand. International Journal of Applied
The cost of designing and installing a solar power Engineering Research Volume 4 No 10 pp. 1911-
with the replaced appliances translates into a 1919
significant reduction of 64.88%, 64.5% and 62.16%
for the one, two and three rooms residential set up Karekezi, S, and Kithyoma, W (2002) Renewable energy
respectively. This is because appliances replacement strategies for rural Africa: is a PV-Ied renewable
costs for the residential apartments were relatively energy strategy the right approach for providing
low compared to the total amount saved on solar modern energy to the rural poor of sub-Saharan Africa.
installation costs. This integrated input-output Energy Policy, Vol 30, 1071-1086.
system design approach thus provides a very good
alternative to reducing the capital cost of residential Mpagalile J.J, Hanna M.A, and Weber R. (2006). Design
solar electricity systems. and testing of a solar photovoltaic operated multi-
seeds oil press. Renewable Energy, Vol 31, 1855-
1866.
REFERENCES
Adeshiyan SA (2010) An output-input design based Mpagalile J.J, Hanna M.A, and Weber R, (2007). Seed oil
techno-economic evaluation of residential solar power extraction using a solar powered screw press
supply system. An MSc Project report at the Industrial Crops and Products, Vol 25 No 1,101-107.
Department of Industrial and Production Engineering
University of Ibadan, Ibadan, Nigeria. Teoman A, Kamil K, and Omer C (1992) Solar assisted
heat Pump and Energy for Domestic Heating in
AI-Salaymeh A, AI-Hamamre Z and Firas S (2009). Turkey. Proceedings of the second World Renewable
Technical & Economical Assessment of the Utilization Energy Congress Reading, UK World Renewable
of Photovoltaic Systems in Residential Buildings The Company. p 687-691
case of Jordan. Faculty of Engineering and
Technology, University of Jordan, Amman 11942,
Jordan. GCREEDER Villavicencio A (2002) Sustainable energy developmentthe case of photovoltaic home systems. Report for
UNEP Collaborating Centre on Energy and
Arne J (2007) Connective Power: Solar Electrification and Environment, Riso National Laboratory, Roskilde,
Social Change in Kenya. World Development Vol. 35, Denmark.
No.1, pp. 144-162
Goswami YG, Kreith D.F, and Kreider J.F (2000) Principle
Eswaramoorthy M and Shanmugam C (2006). Techno- of solar Engineering, second edition, Tailor and
Economic Analysis of a Standalone Solar Francis
26
,/
(
UNIVERSITY OF IBADAN LIBRARY