A smart street lighting system using solar energy

Abstract

This paper demonstrates a prototype for a smart street-lighting system, in which a number of DC street lights are powered by a photovoltaic (PV) source. A battery is added to store the excess energy of the solar panel, which can later be retrieved at night time, or whenever the sunlight is being obstructed by clouds or other forms of shading. A charge controller is used to protect the battery from overcharging and to control the overall system operation. Furthermore, the system is expanded to include a motion sensing circuit, and a dust-cleaning circuit. The overall result is a smart and efficient street lighting system, which can be implemented as a standalone off-grid system, or connected to the rest of the grid as part of a bigger system.

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978-1-5090-3358-4/16/$31.00 ©2016 IEEE
A Smart Street Lighting System Using Solar Energy
Fares S. El-Faouri, Munther Sharaiha, Daoud Bargouth, and Ayman Faza
Electrical Engineering Department
Princess Sumaya University for Technology
Amman, Jordan
Emails: fares_faouri@hotmail.com, msharaiha@gmail.com, barghout_david_92@yahoo.com , a.faza@psut.edu.jo
Abstract—
This paper demonstrates a prototype for a smart
street-lighting system, in which a number of DC street lights
are powered by a photovoltaic (PV) source. A battery is added
to store the excess energy of the solar panel, which can later be
retrieved at night time, or whenever the sunlight is being
obstructed by clouds or other forms of shading. A charge
controller is used to protect the battery from overcharging and
to control the overall system operation. Furthermore, the
system is expanded to include a motion sensing circuit, and a
dust-cleaning circuit. The overall result is a smart and efficient
street lighting system, which can be implemented as a stand-
alone off-grid system, or connected to the rest of the grid as
part of a bigger system.
Keywords—Solar Energy; Smart Systems; Photovoltaics;
I.
I
NTRODUCTION
In the past few years, the Smart Grid has gained a lot of
popularity, mainly due to the fact that it promises a more
intelligent, efficient, and reliable use of the power resources,
while also providing a better quality of service to the
customers. The advances in the technology of renewable
energy sources have also contributed to the increased
dependence on renewable energy, as opposed to the
conventional fossil-based sources. In this paper, we
demonstrate an idea for using renewable energy sources;
namely, solar energy, to power a street lighting system,
which could alleviate a lot of stress on the conventional
power grid, and take us a step further in the process of
moving towards a more intelligent power grid.
We suggest powering street lights completely using
solar energy by connecting the lights to photovoltaic (PV)
panels, which are accompanied by a set of batteries and a
charge controller in order to store energy at day time, and
provide it back for lighting the streets during night-time.
Energy conservation at night is also essential when there is
no movement on the streets; thus, our system is expanded to
include a motion-sensing circuit to activate the use of street
lights only when the lighting is necessary. An additional
feature is added to the PV panel, which is a dust cleaning
circuit, whose purpose is to clean the PV panel from dust
whenever it accumulates on top of it. This helps keep the
efficiency of the panel at reasonable levels, and prevents it
from decreasing due to accumulated dust.
We performed both hardware and software design,
where the hardware part included several circuits, such as
the motion sensing circuit, the dust cleaning circuit, and the
main circuit that connects the street light and the PV panel,
while the software portion of the design focused on
developing the control algorithm, which puts together all the
hardware parts, and controls the operation of the different
circuits in the system.
The software used to run this system was the
Matlab/Simulink, which was used for controlling the system
operation, as well as monitoring it and verifying its
conditions. To ensure proper system operation, several
important parameters were monitored including the solar
irradiation, the open circuit voltage, the short circuit current,
the input and output power to the PV panel, in addition to
the status of the dust cleaning device and the motion sensor,
all of which were monitored and recorded periodically once
every second. While for this project all the monitoring and
control was performed off-grid, the ideas presented can also
be used if the street lighting system was connected to the
grid. The overall goal of this project is to develop a
prototype for an intelligent street lighting system, which
would minimize (or in this case completely eliminate) the
use of electricity coming from the grid, and retrieve all the
required energy from solar panels attached to it. It is also
important to develop ways to improve the operation of the
system, so we added the features of motion sensing, and dust
cleaning, which would reduce the losses due to unnecessary
lighting, and would increase the overall system efficiency by
periodically reducing the amount of dust covering the solar
panel.
The rest of the paper is organized as follows. Section II
presents a summary of related literature. Section III
describes the main circuit and the motion sensing circuit
used in the system, and explains their operation. Section IV
presents the dust cleaning circuit and details its operation.
The details of the MATLAB/Simulink code are presented in
Section V, which also explains the operation of the system in
general. Section VI outlines the results of the project.
Section VII provides an analysis of the system efficiency,
and Section VIII concludes the paper.
II. R
EVIEW OF
R
ELATED
L
ITERATURE
A number of studies were presented in the literature that
targeted various aspects of smart street lighting systems. In
this section, we summarize the ones that were more relevant
to our work. In [1], the authors suggest using LED DC street

lights rather than traditional AC street lights; due to their
higher efficiency, longer lifetime, lower maintenance costs,
and the fact that they are mercury–free, making them
environment-friendly. Similar to the LED lamps are the high
intensity discharge lamps (HID) that could also be
implemented. HID lamps acquire high luminous efficacy
and good color rendition, along with their relatively long
lifetime [2]. In another study, the authors showed that if the
street lighting systems in the city were upgraded to LED, a
64% energy saving is achieved, and 33192 tons of
equivalent carbon dioxide are avoided without even applying
the renewable energy sources [3].
The work in [4] relates the street lighting system to the
overall power grid through the concepts of load demand and
renewable power generation. The results obtained from a
132W LED system are compared with typical results of HID
lamps of similar power levels.
Developing new technologies to further control and
mange street lighting systems was the subject of many
research efforts in the literature. In one such study,
communications topologies to control the street lighting
systems are presented through developing a street lamp
system utilizing the general packet radio service (GPRS),
power line carrier, or the global system for Mobile
communications (GSM) transmissions as presented in [5]
Other studies such as the ones in [6] and [7] focus on
intelligent street lighting systems. They include the design of
a wireless data network-based street lighting system capable
of controlling and monitoring a system that contains a
number of street lights using the ZigBee protocol.
In another study, research was conducted in Egypt to
design a maximum power point tracker (MPPT) for the
street lighting system, which can possibly solve the Egyptian
peak point crisis of load demand if the system is widely
installed, thus handling a commendable portion of the
country's demand [8].
The effect of dust on PV panels was thoroughly studied
in [9], where efficiency degradation of the PV panel due to
dust deposition was verified. Samples of dust ranging from
(0 to 1.963 mg/cm²) were deposited on the glass covering of
the PV panel. The results show a degradation of short circuit
current from 0-49%, respectively. Dust is a major concern to
PV panels' efficiency; thus many solutions emerged to get
rid of it. One innovative solution is to apply an Electro-
dynamic screen across the PV panel, as depicted in [10]. The
electrodes of the screen are activated by high voltage, low
frequency (5-10 Hz) pulses. Accumulated dust particles are
charged electrostatically and repelled by electrostatic forces,
causing the deposited dust to be dispersed.
Street lighting in Jordan consumes 2% of the total
electric energy consumption every year. In this paper it is
suggested powering the street lights completely using solar
energy by connecting the lights to PhotoVoltaic (PV) panels,
which are accompanied by a set of batteries with a charge
controller in order to store energy at day time, and provide it
back for lighting the streets during night-time. Energy
conservation at night is also essential when there is no
movement on the streets, thus in this design a motion-
sensing circuit is used to only activate street lights when the
lighting is necessary. Further features are added to the PV
panel, including a dust cleaning circuit, which cleans the PV
panel from dust whenever it accumulates on top of it, which
keeps the efficiency of the panel at reasonable levels, and
prevents it from decreasing.
III. T
HE
M
AIN
C
IRCUIT
,
AND THE MOTION SENSING CIRCUIT
The main circuit of this system is shown in Fig. 1.
During daytime, the PV panel provides energy to charge the
battery, and during nighttime, the battery provides power to
the main load; i.e., the street light. The charge controller is
necessary to prevent the battery from overcharging during
the day time, and control the interaction between the circuit
elements.
The motion sensing circuit is also an important part of
this system, as it contributed directly to reducing the power
consumption in the main circuit. Depending on the amount
of traffic on the street, there could be times where no
vehicles are passing by especially during late night or early
morning hours, when traffic is usually minimal. During
these times, there is usually no need for street lights to be on,
as there is no use for them, which is why a motion sensor
circuit would provide lots of savings in power.
The motion sensing circuit consists mainly of a Passive
Infrared (PIR) motion sensor, and a relay module. As shown
in Fig. 2, whenever a motion occurs, the PIR sensor triggers
the relay module to connect the charge controller with the
street light. Details of the operation of the PIR sensor can be
found in [11]. If it is night time, the light will be turned ON.
Note that the PV panel and the battery are connected to the
charge controller, which controls the operation of the main
circuit by charging the battery during day time, and
controlling the light operation during night time.
IV. DUST
CLEANING
CIRCUIT
The other important circuit in our design is the dust
cleaning circuit. Dust accumulated for six months decreases
the efficiency of the PV panel by 70% of its original value
[12], so it is important to develop a solution that would
reduce the impact of this highly important issue. Moreover,
it has been found that fine dust particulates significantly
deteriorate the efficiency of the PV panel more than their
coarser peers [13]. The dust cleaning circuit has been
divided into a number of stages: the short circuit current
stage, the output voltage stage, the input power stage, and
the blower stage. From the first two stages the output power
of the PV panel can be calculated in Simulink, and then
compared with the input power. The input power is taken
from a pyranometer signal. If the two quantities did not
match and the pyranometer is reading full-sun or near full-
sun reading, then a triggering signal will be sent to the
blower to activate it.
Figure 3 shows how to obtain the value of the short
circuit current of an operating system, which is then sent to
the main control board; the Arduino MEGA 2560 Board.
The Arduino board is an open source microcontroller

programmable board, which can be easily programmed via
Matlab, and was chosen in this project for its ease of use,
and versatility. Matlab initiates a triggering signal once
every 10 minutes for a period of 1 second during which the
short circuit current reading is sent to the Arduino board.
During the shortening of the PV panel, the charge controller
forces the battery to short as well, which can cause a
problem. This, however, can be resolved by using the same
signal to force an open-circuit across the battery’s terminals
while the PV panel is shorted, as shown in Fig 4.
Fig.1: Charge Controller Combination with the Load, PV Panel,
and Battery.
The instantaneous output voltage of the PV panel is
entered into the Matlab program using a voltage divider, as
shown in Fig. 5.
The input power is taken from the pyranometer's
reading after multiplying it with the PV panel's efficiency
and area. However this signal from the pyranometer needs to
be amplified in order to be accepted by the Arduino. The
pyranometer amplification stage is shown in Fig. 6. With all
the previous quantities determined, Matlab decides whether
or not to trigger the relay (shown in Fig. 7) for a certain
period of time in order to blow away the dust. While in this
system we used an AC blower, this can be replaced with a
DC blower powered from the battery, if the off-grid system
is required.
Fig.2: The Motion Sensor Control Design of the Street-Light.
Fig.3: The Short-Circuit Current Reading Stage of the Dust
Cleaning Circuit
.
V. S
IMULINK CODING
The main brain behind the operation of this system was
the Arduino MEGA 2560. The Arduino controls the entire
operation of the system including the main circuit, the
charge controller, and the dust cleaning circuit.
Programming the Arduino was conducted via block-diagram
coding in the Simulink environment, which is part of the
Matlab software [14], as shown in Fig. 10. In this section,
we provide a brief description of the operation of this code.
Fig.4: The Battery Short-Circuit Prevention Circuit
Fig.5: Output voltage reading stage of the dust dealing circuit.
Fig.6: The Amplification of the Pyranometer's Output Voltage.
Fig.7: The Blower Stage of the Dust Cleaning Circuit.
Figs. 8 and 9 show the experimental setup as seen in the
laboratory environment, with all devices labeled.
First of all, energy consumed in the system is calculated
by incrementing a counter every time the motion sensor
detects movements, and then multiplying the counter by the
power rating of the light and by the amount of time during
which the light the light is ON; that is, 20 seconds per each
signal of the motion sensor, and the resultant consumed
energy will be displayed after it has been converted to kWh.
This is shown on the bottom right portion of Fig. 10.
The first analog input (top left) represents the short-
circuit current reading, which is converted to Amperes, and
saved it in a memory location on the Arduino board. The
lower portion represents the output voltage reading, and the
conversion process to Volts. Unlike the short-circuit current,

which requires shortening the terminals of the panel, and
acquiring a reading, there is no need to save the value of the
output voltage because the reading is continuous and is
displayed in real time.
Fig. 8 -Laboratory Setup
Fig. 9 - Laboratory Setup Including the Solar Panel
Both values of current and voltage are multiplied to
yield the actual maximum power that the PV panel is able to
produce. The lower left portion obtains the pyranometer's
reading, and converts it into W/m², after multiplying it by
the panel's efficiency and area. The resulting value is then
compared with the output power previously found.
Depending on this comparison operation (shown on the
bottom of Fig. 10), and by taking the maximum and
minimum derate factors of dust into account, a signal is sent
to the relay module responsible for triggering the blower.
This signal will be sent if the two previous power quantities
did not match AND the pyranometer was giving a non-
cloudy reading. The upper right portion of Fig. 10 shows the
pulse generator responsible for triggering the relay module
that shorts the PV panel for 1 second every 10 minutes
(while also open- circuiting the battery at that same second)
to obtain the value of the short circuit current.
VI. E
XPERIMENTAL RESULTS
A number of graphs were obtained when running the system
explained above, and in this section we show the results
obtained, and we explain them as they relate to the objective
of our project. The two cases that were studied represent a
sunny day and a cloudy one.
Figure 11 shows the solar radiation during 50 minutes
of time on a cloudy day. As can be seen in the graph, there is
a high amount of intermittency in the power received by the
solar panel due to the effect of clouds constantly disrupting
the availability of sun rays. Figures 12 and 13 demonstrate
the short circuit current and the output voltage of the PV
panel, respectively, during fifty minutes of time on cloudy
day.
Figure 14 shows the irradiance on a sunny day. While
there are a few short spikes due to sudden cloud shading,
during which the power is significantly reduced, the amount
of solar irradiance is relatively stable around 1000kW/m2,
which is typical for a mostly sunny day. Figures 15 and 16
illustrate the short circuit current and the open circuit voltage
during the same fifty minutes of time on a sunny day.
As can be seen from the figures, during cloudy days, the
amount of solar energy that we obtain is generally less than
in the case of the sunny day. More importantly, however, the
large amount of variation that can be seen in the voltage,
current, and consequently the power, is mainly due to the
constant variation in the amount of solar energy obtained
during the cloudy day.
These measurements show the proper operation of the
system in terms of its ability to monitor the amount of solar
irradiance. These values are then compared to the readings
of the pyranometer, as explained earlier to help detect
whether or not there is dust accumulated on the panel, and
Figure 10 - A Block Diagram of the Simulink Code

obtain a more efficient operation for the system.
Fig.11: The Solar Irradiance During Fifty Minutes of Time on a
Cloudy Day.
Fig.12: The Short Circuit Current of the PV Panel During Fifty
Minutes of Time on a Cloudy Day.
Fig.13: The Output Voltage of the PV Panel During Fifty Minutes
of Time on a Cloudy Day.
Finally, the system can be controlled entirely from the
computer using the Simulink code described earlier. Manual
control has also been added to manually turn on -or off-
every component of the system, including the dust blower
and the DC light.
Having the system installed considering the previous
constraints, particulates of sand (so as to simulate a dust
condition) were scattered on top the PV panel gradually. The
PV panel's output voltage and short circuit current started to
decrease, and consequently so did the output power of the
panel, whereas the pyranometer indicated a certain input
power, that did not yield the desired output power in the
simulink program. Therefore, the blower started to operate
in order to restore the normal operation of the PV panel; that
is, the operation without dust.
Fig.14: The Solar Irradiance During Fifty Minutes of Time on a
Sunny Day.
Fig 15: The Short Circuit Current of the PV Panel During Fifty
Minutes of Time on a Sunny Day.
Fig 16: The Output Voltage of the PV Panel During Fifty Minutes
of Time on a Sunny Day.
VII. EFFICIENCY
OF
THE
SYSTEM
An efficiency analysis can be conducted at any instance
of time, especially when the blower is turned on. A
comparison of efficiencies before and after the blower's
operation can verify the adequacy of the blower, the
accumulation amount, and the overall system response to
dust. Figure 17 presents the flowchart of efficiency analysis
that can be conducted by model base programming platform
Simulink.
It must be mentioned that the maximum theoretical
efficiency limit for a PV panel is unlikely to be achieved,
even in ideal conditions. The proposed system increases the
efficiency of the PV panel by dealing with an external
condition; that is dust, in order to achieve the maximum
practical efficiency of the PV panel. To further enhance the

efficiency of cleaning, more than one blower at several
angles of the PV panel can be installed in order to effectively
dispose of all remaining dust particles, taking all possible
angles of the PV panel (with equidistant spacing) into
account.
Fig.17: Flowchart of efficiency analysis programming on Matlab
Simulink.
VIII. C
ONCLUSION
This paper presents a smart street lighting system, in
which a conventional street light is modified to obtain its
power from solar energy. Additional features were added
that improve the operation of the system either by reducing
the overall power consumption, which was achieved by
using a motion sensor, or by using a dust cleaning circuit,
which constantly keeps the efficiency of the panel at a
certain maximum value.
Matlab’s Simulink, the same program that controls the
operation of the system, illustrates output power, output
voltage, and short circuit current during real time, as well as
calculating the energy consumed by the DC lights. Future
work for this project include adding more intelligent features
to the system such as communication capabilities, data
logging, and on-grid connection capability. Proposed
topologies to connect a PV system with the grid include the
multifunctional bidirectional converters that rely on a
predetermined switching mechanism and the integration of
two flyback converters, such as the one described in [15].
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