Development of a Stand-alone Solar Powered Bus Stop
Development of a Stand-alone Solar
Powered Bus Stop
Mohd Afzanizam Mohd Rosli1, Mohd Zaid Akop 2, Muhd Ridzuan
Mansor3, Sivarao S.4
Faculty of Mechanical Engineering, Universiti Teknikal Malaysia Melaka,
76100 Durian Tunggal, Melaka.
4
Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia
Development
of 76100
a Stand-alone
Solar Powered
Melaka,
Durian Tunggal,
Melaka. Bus Stop
1,2,3
Mohd Afzanizam MohdEmail:
Rosli1, Mohd
Zaid Akop 2, Muhd Ridzuan Mansor3, Sivarao S.4
1afzanizam@utem.edu.my
1,2,3
Faculty of Mechanical Engineering, Universiti Teknikal Malaysia Melaka, 76100 Durian
Tunggal, Melaka.
ABSTRACT
4
Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, 76100 Durian
Tunggal, Melaka.
This paper presents the development of a stand-alone solar photovoltaic
(PV) system for busEmail:
stop 1afzanizam@utem.edu.my
at Universiti Teknikal Malaysia Melaka,
Malaysia. The design intent for the bus stop was to provide lighting
and information to the bus stop
users using reliable renewable energy
ABSTRACT
system as well as to promote green technology awareness to the university
stand-alone
system wassolar
designed
to power
twosystem
units for
of bus stop at
This paperresidences.
presents theThe
development
of PV
a stand-alone
photovoltaic
(PV)
Universiti CFL
Teknikal
Malaysia
Malaysia.
designatintent
for stop.
the bus
stop
was to provide
lamps
and anMelaka,
LED display
unit The
installed
the bus
Five
units
lighting and
to the
bus stop users
using reliable
renewable
system
of information
polycrystalline
photovoltaic
modules
with 110W
rating energy
each and
fouras well as to
promote green
awareness
to the
university
residences.
PV system was
deep technology
cycle battery
units were
utilized
to provide
threeThe
daysstand-alone
of autonomy
designed toperiod
powerfor
two
units of
CFL lamps
and an
LED
display
unit installed
at the
bus stop. Five
system
operation.
A part
from
that,
15 degree
of tilt angle
was
units of polycrystalline
photovoltaic
modules with
110W optimum
rating each
and four
deep cycle battery
selected for PV
module placement
to provide
energy
generation
units were utilized to provide three days of autonomy period for system operation. A part from that,
as well as self cleaning for the modules. After the bus stop structure
15 degree of tilt angle was selected for PV module placement to provide optimum energy
construction, the PV system was installed and commissioned. Final results
generation as well as self cleaning for the modules. After the bus stop structure construction, the PV
the commissioning
process
showed
is able toprocess
operate showed that
system wasfrom
installed
and commissioned.
Final
resultsthat
fromthe
thesystem
commissioning
successfully
as
per
design
requirement.
the system is able to operate successfully as per design requirement.
KEYWORDS:
Solar photovoltaic,
Bus stop, Stand-alone
system
KEYWORDS:
Solar photovoltaic,
Bus stop, Stand-alone
system
1.0
INTRODUCTION
Photovoltaic or PV is currently one of the most attractive options for renewable energy
resources in the world. Malaysia which is blessed with yearly average solar irradiance of
1400 to 1900 kWh/m2 is considered to be in a very advantageous position to harness the
unlimited energy towards PV applications to cater current domestic energy demand
(Malaysian PV Handbook, 2009). The technology offers free and renewable energy, no
emission effects during energy production, help to reduce dependency to conventional
power supply, as well as easy to install and maintain due to its modular characteristics
(Chow, 2010).
Up to date, solar photovoltaic (PV) system application is divided into two distinctive
categories, which are grid-connected system and stand-alone or off-grid system. The grid
connected PV system operates by linking the solar PV with the utility-grid connection,
where as the stand alone PV system operates without connection to the utility grid and
ISSN: 2180-1053
3 energy
No. 2 July-December
2011solar PV as well
55 as
utilize a battery system
to store the Vol.
excess
generated by the
supplying the needed energy when no power from the sun is available. Both system are
power supply, as well as easy to install and maintain due to its modular characteristics
(Chow, 2010).
Journal of Mechanical Engineering and Technology
Up to date, solar photovoltaic (PV) system application is divided into two distinctive
categories, which are grid-connected system and stand-alone or off-grid system. The grid
connected PV system operates by linking the solar PV with the utility-grid connection,
where as the stand alone PV system operates without connection to the utility grid and
utilize a battery system to store the excess energy generated by the solar PV as well as
supplying the needed energy when no power from the sun is available. Both system are
widely applied especially in Malaysia, however the stand-alone system offer notable
advantage of able to operate in remote areas where utility-grid connection are not viable
(Zekai, 2008).
In this project, an innovative design of bus stops is proposed where the infrastructure is to
be equips with lamps and electrical signboard powered by solar PV energy system. The new
system is aimed to provide higher level human comfort as well as information to user, and
the prototype is targeted to be applied in Main Kampus, Universiti Teknikal Malaysia
Melaka. Currently, bus stops in UTeM is designed without any equipment to provide proper
notice board and LED display to give better information for the public. This paper described
the overall design and development process for the UTeM solar powered bus stop such as
PV system sizing, structure design and development as well as PV system installation and
commissioning.
2.0
METHODOLOGY
The overall research methodology implement in this project is shown in Fgure 1 below.
56
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Development of a Stand-alone Solar Powered Bus Stop
Start
Project planning
Literature Review on Current Design of Solar
System
System Development
Modify
Evaluation
Not good
Good
System Installations
Modify
Evaluation
Not good
Good
System Testing
Performance
Monitoring
End
FIGURE
1 Flow Chart
FIGURE 1 Overall
Research
Overall Research Flow Chart
Among the important stage in this project was the system development where the sizing of
the PV standalone system is conducted. In order to attain an optimum design for the system,
several sizing criteria such as location selection, design specification, determination of PV
modules and battery capacity etc. were carefully calculated based on MS1837:2005 PV
standard requirements (Malaysian Standard, 2005). The structure was later designed to
accommodate the system sizing results using Solidworks CAD software. System testing and
commissioning were performed in the final stage of the project to ensure that the PV system
able to operate as per requirement.
3.0
SYSTEM SIZING
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57
accommodate the system sizing results using Solidworks CAD software. System testing and
commissioning were performed in the final stage of the project to ensure that the PV system
ableJournal
to operate
as per requirement.
of Mechanical
Engineering and Technology
3.0
SYSTEM SIZING
3.1
Selection of Bus Stop Location
3.1
Selection of Bus Stop Location
The first approach in designing the UTeM solar bus stop was to choose the suitable location
The
firststructure.
approachThis
in designing
the UTeM
solar
stopthat
wasthe
to solar
choose
the suitable
location
for the
is very crucial
in order
to bus
ensure
modules
installed
later
for
the
structure.
This
is
very
crucial
in
order
to
ensure
that
the
solar
modules
installed
later
on will have exposed to adequate sunray throughout the entire day for maximum power
on
will
have
exposed
to
adequate
sunray
throughout
the
entire
day
for
maximum
power
generation. The surrounding of the bus stop location was also ensured to be clear from
generation.
Thesuch
surrounding
of the
bus structure
stop location
was also
ensured
to be clear
shading sources
as tress and
nearby
especially
to the
solar modules.
Thefrom
bus
shading
sources
such
as tress
and nearby
the function.
solar modules.
The bus
stop must
also be
easily
accessible
to thestructure
users toespecially
serve its to
main
The proposed
stop
must
be easily
the users
to serve
its main function. The proposed
location
of also
the UTeM
solaraccessible
bus stop istoshown
in Figure
2 below.
location of the UTeM solar bus stop is shown in Figure 2 below.
FIGURE 2
FIGURE
2 Location
Bus
FIGURE 2UTeM
UTeMSolar
Solar
BusStop
Stop
Location
UTeM Solar Bus Stop Location
3.2
Load Determination
3.2
Load Determination
The details of the electrical appliances designed for the bus stop and its power rating is
The
details
of the
electrical
appliances
for the of
busthestop
andselected
its power
rating on
is
shown
in Table
1 below.
Based
on Tabledesigned
1, the majority
loads
operated
shown
in Table
on of
Table
theofmajority
thecomponent
loads selected
operated
on
AC current.
This1isbelow.
mainlyBased
because
low 1,
cost
acquiringofthe
compared
to DC
AC
current.
This is mainly
of low
cost of acquiring
thedivided
component
compared
to DC
current
components.
A partbecause
from that,
the system
load is also
into two
cases which
current
part loads.
from that,
system
is also divided
into
casestowhich
are
withcomponents.
and without Aspare
The the
spare
loadsload
are incorporated
into
thetwo
design
cater
are
and without
loads.
Thein spare
loads are
intohours
the design
cater
for with
unexpected
higherspare
power
usage
the future.
Theincorporated
total load per
in the to
case
of
for
unexpected
higher
power
usage in
theand
future.
The
total
load loads
per hours
in the
case of
without
spare load
is 953
Watt-hours
daily
in the
case
of spare
is 1269
Watt-hours
without
daily. spare load is 953 Watt-hours daily and in the case of spare loads is 1269 Watt-hours
daily.
TABLE
TABLE 1 Load profile for
UTeM1solar bus stop in a day
TABLE
1 bus stop in a day
Load profile for UTeM
solar
Load profile for UTeM solar bus stop in a day
Load
Power/Unit Operating Operating
No
Type Quantity Power/Unit Operating Operating
Load
Detail
(W)
Time
hour/Day
No
Type Quantity
Detail
(W)
Time
hour/Day
1 CFL Lamp
AC
2
18
7pm – 1am
6
12 CFL
AC
2
18
7pm
– 1am
6
LED Lamp
1
49
8am
–
14
Display
10pm–
2 LED
AC
1
49
8am
14
Internal
DC &
3
1
8.5
6
System
AC
*13A
4
AC
1
100
1
socket
58 *Spare
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5
AC
2 Vol. 3 No.
18 2 July-December
6
loads
Total
Total
Power
Power
(Wh)
(Wh)
216
216
686
686
51
100
216
3
4
5
3.3
Display
Internal
System
*13A
socket
*Spare
loads
Development of a Stand-alone
Solar Powered Bus Stop
10pm
DC &
AC
1
8.5
-
6
51
AC
1
100
-
1
100
AC
2
18
-
6
216
System Specification and Tilt Angle
Several parameters have been determined for the design specification of the solar bus stop.
First and foremost, the new UTeM solar bus stop is set to operate as a standalone system,
where the power source is generated through PV modules only. The system is also set to be
operated using 12V system voltage and must be able to operate up to 3 days of autonomy (in
the case where zero sunlight occurred). The estimated achievable maximum solar radiation
per day for the system is set to 3 peak sun hours and because the bus stop is a standalone
photovoltaic system, the maximum depth of discharge for the battery used is the system is
set to 80% capacity. The solar module is set to be placed on top of the bus stop roof to avoid
any shading and to optimize the bus stop area. Hence, another important parameter that was
determined was the tilt angle for the solar module installation. The location for the bus stop
is roughly at the latitude 2°18'51.61"N and longitude 102°19'8.17"E, where, optimum tilt
angle for the solar module is from 2° to 3° facing south. However, it is recommended that
for sites at latitudes between 15°S and 15°N, a tilt angle of 15° is used. Hence, the tilt angle
selected for the bus stop design is 15° to enable optimum energy generation as well as self
cleaning for the modules. Based on solar irradiation data for Malaysia, the approximate
average solar irradiance for the given latitude is 1400 W/m2 (Sulaiman et al., 2008).
3.4
Battery and Module Sizing
Based on load data in Table 1 and design specifications, the sizing of the battery unit and
the solar PV modules were performed. The determination for the number of batteries and
PV modules were carefully conducted to ensure optimum sizing of the system can be
achieved, which will benefits in lowering down the overall system cost as well as ensuring
the system is able to operate efficiently. The sizing approach for standalone system is more
delicate because the system operates solely on solar energy and energy from the batteries,
compared with grid connected system. The battery must be able to supply the required
power for minimum 3 days autonomy while the PV modules must be able to supply the
power during sunlight as well as charging the battery to its maximum capacity continuously.
Table 2 below shows the final result for the battery and PV module sizing.
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59
Journal of Mechanical Engineering and Technology
TABLE 2
TABLE
1 Sizing
for Battery
andModules
PV Modules
Sizing
for Battery
and PV
Sizing Details
A. Battery
i.
Amp-hour required excluding spare load (Ah)
ii.
Amp-hour required including spare load (Ah)
iii. No of battery need
B. PV Module
i.
Maximum power, Pm (W)
ii.
Maximum voltage, Vm (V)
iii. Maximum current, Im (A)
iv. Short-circuit voltage, Voc (V)
v.
Short-circuit current, Isc (A)
vi
Total module required excluding spare loads
vii. Total module required including spare loads
viii. Array configuration
3.5
Value
297.8
396.6
4
110
17.2
6.4
21.7
6.9
4
5
5x1
Balance-of-system (BOS) Sizing
The final procedure for the sizing is to determine the specification for charge controller and
inverter. The charge controller is used to regulate the power from the PV modules to the
loads and vice versa efficiently. The inverter in the other hand is selected to convert the DC
voltage produced from the PV modules to AC voltage needed for the load operations (CFL
lamps, LED display etc.). The results of the balance of system sizing are shown in Table 3
below.
TABLE 3
TABLE 3 Balance-of-system (BOS) for UTeM Solar Bus Stop
Balance-of-system (BOS) for UTeM Solar Bus Stop
BOS Sizing Details
A. Charge Controller
i. System voltage : minimum/maximum (V)
ii. Total rated solar current (A)
iii. Total maximum array current (A)
iv. Total rated load current (A)
v. Total maximum load current (A)
B. Inverter
i. AC system voltage (V)
ii. AC system frequency (Hz)
iii. Power factor (cos(pi))
iv. Rated VA based on excluding spare loads
v. Rated VA based on including spare loads
60
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Value
12/24
18.5
26.5
7.8
19.2
240
50
0.85
110
270
July-December 2011
Development of a Stand-alone Solar Powered Bus Stop
A part from that, another important parameter for the BOS is the appropriate selection of
cable size to minimize the power transmission lost in the cables. Due to the small amount of
energy generated by the PV modules, thus the sizing process in this project was also focused
to reduce any losses that may be created in the system which can deteriorate the system
performance. The diameter of cable size selected is 4mm for running from the charge
controller to the loads as well as from the batteries to the charge controller and 6mm cable
diameter for cable designed from the PV modules to the charge controller. The selected
cable sizes for the whole system were carefully calculated to permit maximum cabling
losses of 4% based on requirement stated in the Malaysian Standard (Malaysian Standard,
2005).
3.6
Results of System Sizing
Based on the system sizing, the appropriate components for the UTeM solar bus stop system
were selected. The design specific yield of the system is 1037.1 kWh/kWp. The installation
quality of the designed bus stop measured in term of performance ratio was found to be
approximately 74% which satisfy the MS1837:2005 PV standard requirements (Malaysian
Standard, 2005). A timer was also incorporated in the system to control precisely the
operation hours of the loads in the system. Table 4 and Figure 3 below show the description
of the selected equipments for the standalone PV system and the system overall schematic
diagram.
TABLE
4
TABLE 4 Equipments
for UTeM
solar bus stop
Equipments for UTeM solar bus stop
No
Item
1 Solar Module
2 Battery
3
4
Charge Controller
Inverter
Quantity
Desciptions
5
110 W, 12V, Polycrystalline. Brand: SolarTif
4
100 Ah, 12V, JXH100-12 Valve Regulated Lead
Acid. Brand: MPower
1
Model PL40, 12-48V, 30A. Brand: Phocos
1
Standalone
Sinewave
Inverter,
Model
Picollo.Brand: ASP
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Journal of Mechanical Engineering and Technology
FIGURE 3
FIGURE 3 Schematic Diagram
of the3 UTeM Solar Bus Stop
FIGURE
Schematic Diagram of the UTeM Solar Bus Stop
Schematic Diagram of the UTeM Solar Bus Stop
4.0
4.0
BUS
BUS STOP
STOP DESIGN
DESIGN AND
AND CONSTRUCTION
CONSTRUCTION
The
The design
design intent
intent is
is for
for the
the bus
bus stop
stop to
to provide
provide lighting
lighting and
and visual
visual display
display to
to the
the users
users of
of the
the
bus
stop.
A
part
from
that,
the
bus
stop
structure
must
also
be
able
to
accommodate
the
bus stop. A part from that, the bus stop structure must also be able to accommodate the solar
solar
modules
modules as
as well
well as
as the
the rest
rest of
of the
the balance
balance of
of system
system components.
components. Acknowledging
Acknowledging the
the above
above
requirements,
a
design
for
the
UTeM
bus
stop
was
proposed
and
shown
in
Figure
4
requirements, a design for the UTeM bus stop was proposed and shown in Figure 4 below.
below.
FIGURE 4
FIGURE 4 UTeM
UTeM Solar
Solar Bus
Bus Stop
Stop Design
Design
The UTeM bus stop structure encompassed several features. The roof of the structure is
ISSN: 2180-1053
Vol. 3 No. 2 July-December 2011
tilted at 15 degree
from horizontal
plane to enable tilt angle of 15 degree for the module
installation. The bus stop foundation is needed to be flat to ensure the tilt angle for the
62
Development
FIGURE 4 of a Stand-alone Solar Powered Bus Stop
UTeM Solar Bus Stop Design
The UTeM bus stop structure encompassed several features. The roof of the structure is
tilted at 15 degree from horizontal plane to enable tilt angle of 15 degree for the module
installation. The bus stop foundation is needed to be flat to ensure the tilt angle for the
modules can be achieved. The roof structure also houses the CFL lamps and LED display
unit. Due to the location of the LED display unit where it is placed on the front of the bus
stop roof facing the main road, the display is required to be fabricated based on IP65 casing
requirement for ensuring reliable outdoor performance. The overall structure of the bus stop
will be made from concrete as well as for the base of the bus stop. The balance-of-system
components are located separately in a special housing behind the bus stop structure for ease
of maintenance and security control. Figure 5 below show the UTeM bus stop in the end of
the construction process.
FIGURE 5
BusBus
Stop
after
Construction
FIGUREUTeM
5 UTeM
Stop
after
Construction
FIGURE 5
UTeM Bus Stop after Construction
5.0
SYSTEM INSTALLATION AND COMMISSIONING
After the bus stop structure was constructed, the stand-alone PV system was later installed
at theINSTALLATION
location. Simple L-shapeAND
brackets
were first placed on top of the structure roof acting
SYSTEM
COMMISSIONING
as the mounting points for the PV modules. Five units of PV modules were installed in 5x1
array configuration as per sizing requirement at 15 degree tilt angle. Later, the CFL lights
the bus stop
structure
waswere
constructed,
thebus
stand-alone
PV system
was later installe
and LED
display unit
installed on the
stop. The batteries
and balance-of-system
components
were
installed
separately
on
a
special
housing
behind
the
bus
stop. Wires
e location. Simple L-shape brackets were first placed on top of the structure
roof actin
connecting the modules, loads and the rest of the PV system are secured inside conduits to
e mounting
points for the PV modules. Five units of PV modules were installed in 5x
ensure safety to the users as well as to protect from surrounding effect such as rain water
configuration
per itsizing
requirement
at 15
tilt angle.
that mayascause
to deteriorate
prematurely.
Thedegree
wires connecting
theLater,
modulesthe
andCFL
the light
balance-of-system
is also
in ground
purposes.
Thebalance-of-system
installed PV
LED display
unit were housing
installed
on burried
the bus
stop. for
Thesafety
batteries
and
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2011
63 7
system
on
the
bus
stop
and
the
PV
balance
system
are
shown
in
Figure
6
and
Figure
ponents were
installed
separately
on
a
special
housing
behind
the
bus
stop. Wire
below.
array configuration as per sizing requirement at 15 degree tilt angle. Later, the CFL lights
and LED display unit were installed on the bus stop. The batteries and balance-of-system
components
were installed
separately
on a special housing behind the bus stop. Wires
Journal of Mechanical
Engineering
and Technology
connecting the modules, loads and the rest of the PV system are secured inside conduits to
ensure safety to the users as well as to protect from surrounding effect such as rain water
that may cause it to deteriorate prematurely. The wires connecting the modules and the
balance-of-system housing is also burried in ground for safety purposes. The installed PV
system on the bus stop and the PV balance of system are shown in Figure 6 and Figure 7
below.
FIGURE 6 UTeM Stop with Stand-alone PV System
FIGURE 6
UTeM Bus Stop with Stand-alone PV System
64
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Development of a Stand-alone Solar Powered Bus Stop
FIGURE 7 Housing for Batteries
and Balance-of-system
Components
FIGURE
7
Housing for Batteries and Balance-of-system Components
6.0
CONCLUSION
In conclusion, the standalone solar PV system for UTeM green bus stop was successfully
developed in this project. The solar PV system comprised of five polycrystalline modules in
5x1 array configuration and four deep cycle batteries which give power to two units of CFL
lamps and a LED display unit. The bus stop structure was design and constructed to
accommodate the module tilt angle of 15 degree. Results from the testing and
commissioning process performed show that the solar PV system was able to perform as per
design requirement. The solar powered bus stop developed in this project was proven not
only to perform as conventional bus stop, but also able to provide human comfort and
information to the users as well as promoting green technology within the university and its
residence.
7.0
ACKNOWLEDGEMENT
The authors would like to thank Universiti Teknikal Malaysia Melaka for providing the
support and fund for accomplishment of this project. The project was funded under UTeM
top-down research grant PJP/2010/FKM(15A)-S715.
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Journal of Mechanical Engineering and Technology
8.0
REFERENCES
PV Industry Handbook. 2009. Pusat Tenaga Malaysia. Malaysia.
T.T. Chow. 2010. A Review on Photovoltaic/thermal Hybrid Solar Technology, Journal of Applied
Energy, Vol. 87, pp. 365-379.
S. Zekai. 2008. Solar Energy Fundamental and Modeling Technique: Atmosphere, Environment,
Climate Change and Renewable Energy. 1st Ed. Ginora, Spain: Springer
Installation of Grid Connected Photovoltaic (PV) System, Malaysian Standard MS1837:2005,
SIRIM, Malaysia.
Sulaiman S., Kamaruzzaman S., and Ahmad M.O. 2008. Solar Irradiation Handbook for
Photovoltaic Systems Design in Malaysia. Solar Energy Research Institute, Universiti
Kebangsaan Malaysia, Malaysia. ISBN: 9789675048326.
66
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