Design and Simulation of a Solar Parking System to meet all Energy needs of 10 Electric Cars

Abstract

Electric vehicles are a growing segment of the green transport industry and are helping reduce the carbon footprint of the global transport sector. However, EV adoption is slow due to the lack of charging infrastructure throughout the Newfoundland. We propose the design and control of a solar PV parking system that also serves as a charging station for 10 electric vehicles. The main source of power for our system would be solar PV and a battery bank for the storage of excess energy to be used during off-daylight hours. The sizing, design, and feasibility analysis of the system were performed in HOMER Pro. After that, the major components of the system were modeled in Simulink including PV, Battery, inverter, Load, and Controller. The solar charge controller utilized in our design used a DC-DC buck-boost converter running on the Perturbation and Observation (P&O) Algorithm. The system design details and simulation results are included in the paper.

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Presented at 30th IEEE NECEC Conference. November 18, 2021 St. John's, NL
1
Design and Simulation of a Solar Parking System to
meet all Energy needs of 10 Electric Cars
Ali Husnain
Department of Electrial Engineering
Memorial University of Newfoundland
St. John’s, NL, Canada
ahusnain@mun.ca
Dr. Tariq Iqbal
Department of Electrial Engineering
Memorial University of Newfoundland
St. John’s, NL, Canada
tariq@mun.ca
Abstract—Electric vehicles are a growing segment of the
green transport industry and are helping reduce the carbon
footprint of the global transport sector. However, EV adoption
is slow due to the lack of charging infrastructure throughout
the Newfoundland. We propose the design and control of a
solar PV parking system that also serves as a charging station
for 10 electric vehicles. The main source of power for our
system would be solar PV and a battery bank for the storage of
excess energy to be used during off-daylight hours. The sizing,
design, and feasibility analysis of the system were performed in
HOMER Pro. After that, the major components of the system
were modeled in Simulink including PV, Battery, inverter,
Load, and Controller. The solar charge controller utilized in
our design used a DC-DC buck-boost converter running on the
Perturbation and Observation (P&O) Algorithm. The system
design details and simulation results are included in the paper.
Keywords—solar parking, renewable energy, EV charging
station, battery storage, control
I. INTRODUCTION
The alarming situation of global warming and climate
change has been a cause for concern for a while now. The
industrialization of the world has seen a steep increase with
the increase in population of Earth. The use of fossil fuels to
meet human energy needs as well as the widespread use of
gas-powered vehicles as a mode of transportation has been
one of the biggest contributor to the deteriorating climate
landscape.
According to a study carried out by EPA, a good 63% of
the United States’ current electricity needs are being met by
the burning of fossil fuels, mostly coal and natural gas.
Electricity production accounts for 26.9% of greenhouse gas
emissions as of 2018 [1]. Similarly, the greenhouse gas
emissions from transportation account for another 28% of the
total U.S. greenhouse gas emission, making it the largest
contributor of GHG emissions in U.S [2]. Unfortunately, the
situation in many other countries around the world is no
different and in most cases worse than that of U.S.
To counter this alarming issue of global warming and
climate change, a lot of new projects are being undertaken,
which include the replacement of fossil fuel electricity
generation plants by renewable energy plants and the use of
battery powered electric vehicles instead of internal
combustion engines. However, there are many challenges
that stand in the way of the successful execution of these
projects.
II. LITERATURE REVIEW
Given the alarming situation of global warming that we
are in, the adoption of electric vehicles as a common mode of
transportation has been ongoing for the past few years. This
means that a number of projects and research studies have
been undertaken to design and optimize charging stations
that take electricity from Grid, PV or other resources.
We looked at a number of similar studies and projects
that have been undertaken to develop a better understanding
of what is at stake when designing a solar powered EV
charger. A feasibility study carried out by Dutch researchers
speaks about the solar energy potential at workplaces in
Netherlands, enough to charge the battery powered electric
vehicles under the use of workplace employees. The project
presents two different mechanisms of 1. Charging the electric
vehicles on weekdays only and 2. Charging electric vehicles
all 7 days of the week. The optimal storage size required to
bring down the grid dependency by 25% is also evaluated
[3].
Another similar study undertaken by researchers at
Aligarh Muslim University campus building makes the use
of the campus parking as a means to erect a solar PV system
in order to charge a small battery powered electric vehicle
with a 10kWh lithium-ion battery pack [4].
The following study gives a comprehensive review on
solar powered electric vehicle charging systems and lists
down the industry best practices to be kept in mind while
designing a solar PV powered charger [5]. Another similar
project shows the implementation of a grid-integrated PV
battery system for both electric vehicle charging and
residential applications [6].
We will also refer to the bibliographical review carried
out by Mohammad Saad Alam et al. on the electric vehicles
standards while designing an EV Charger [7].
III. CURRENT RESEARCH
A. Research Problem
While the renewable energy generation and distribution
projects face a wide variety of challenges. There is really
only one major issue that hinders the worldwide adoption of
electric vehicles apart from a huge gap in demand and supply
of EVs, and it is the lack of charging infrastructure in cities
and on roads across the world. There is a popular term in the
electric vehicle community known as “range anxiety”, which
refers to the fear of running out of electricity while driving
an electric vehicle due to a lack of EV charging stations.
B. Proposed Solution
In order to counter this issue, we are going to propose the
design of a simple yet economical solar parking system,
which makes the use of solar energy as a source to generate
electricity and produces enough electricity to fulfil the power
needs of 10 electric vehicles. The project will be designed
using products that are easily available commercially,
making it easy to implement this project in the real world.

Presented at 30th IEEE NECEC Conference. November 18, 2021 St. John's, NL
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C. Scope of Work
The location we have chosen in order to install our solar
PV parking project is in St. John’s, NL, Canada. The solar
panels would be mounted on a shed like structure in the
parking lot next to the International Office at Memorial
University of Newfoundland, St. John’s NL. The storage
scheme being utilized in this system are rechargeable
batteries. The nominal power at which both the wall chargers
would be rated as well as the vehicle would charge is 7.7
kW. The hours of operation of the charger would be 8.8
hours (9 hours). The current project being designed would be
able to charge 10 vehicles in a day. The parking would be a
shed type structure made up of carbon steel.
IV. RESOURCE DATA COLLECTION
A. Location
The location that we have chosen is a parking lot next to
the International Office at Memorial University of
Newfoundland, St. John’s NL.
Figure 1: Locaton for PV Parking System
B. Solar Potential
The solar potential at our chosen site is as following;
Figure 2: Monthly Average Solar Global Horizontal
Irradiance Data
The values are as given below in Table 1;
Table 1: Monthly Solar Global Horizontal Irradiance
Data
Month
Clearness
Index
Daily Radiation
(kWh/m2/day)
Jan
0.434
1.280
Feb
0.479
2.110
Mar
0.501
3.310
Apr
0.465
4.180
May
0.439
4.740
Jun
0.444
5.140
Jul
0.437
4.880
Aug
0.455
4.390
Sep
0.447
3.310
Oct
0.426
2.150
Nov
0.389
1.270
Dec
0.403
1.020
C. Vehicle Chosen
While there is a wide variety of fully electric battery
powered vehicles present in the market as of today, we
decided to go with the all-famous Tesla Model 3, which is
one of the best-selling electric car in the world. Being widely
adopted, Tesla Model 3 has plenty of after-market support in
Canada or anywhere around the world. Tesla Model 3 comes
in a number of different trims each with different battery
packs and electric motors in them. The model we have
chosen to go with is called Tesla Model 3 Standard Range
Plus and is the base model of the Tesla Model 3 lineup.
Figure 3: Tesla Model 3
The technical specifications of the car are as follows;
Table 2: Technical Specifications of Tesla Model 3
Pricing
MSRP
CA$54,610
Powertrain
Engine
Electric (rear, center)
Power
283 hp (211 kW)
Hybrid / Electric
Battery type
Lithium-ion (Li-ion)
Energy
50.0 kWh
Voltage
360 V
Charging times
 120V: N/A
 240V: 8.5 h
 400V: 0.8 h
 Fuel efficiency / Autonomy
Electric autonomy
402 km
CO₂ emissions
0 g/km
Model 3 has onboard charger which is rated at 7.7 kW at 32
A.
D. Solar Panels
For this project, we have chosen solar panels from
Canadian Solar based on the local availability of panels,
record testing and performance of the manufacturer.
The ratings for the chosen panel are as follows:
 Model: Canadian Solar MaxPower CS6U-340M
 Voltage: (1500 V)

Presented at 30th IEEE NECEC Conference. November 18, 2021 St. John's, NL
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 Cell efficiency: 20.0%
 Low Irradiance Performance: 96.5%
 IP67 Junction box for long-term weather
endurance.
 Heavy snow load: 5400 Pa.
 Wind load: 2400 Pa.
E. Storage
For our storage, we chose the Tesla Powerwall,
which is a fully-integrated AC battery system for
residential or light commercial use. The specs of the
chosen storage system are given below
Energy Capacity
 13.5 kWh
 100% depth of discharge
 90% round trip efficiency
Power
 7kW peak / 5kW continuous
F. Wall Charger
Tesla Wall Connector is an efficient and convenient
home charging solution that lets you plug your vehicle in
overnight and start your day fully charged.
 Up to 44 miles (77 km) of range per hour of charge
 Up to 11.5 kW / 48 amp output
 Wi-Fi connectivity (2.4 GHz 802.11 b/g/n)
V. STEADY STATE MODELING
A. System Sizing
We made the use of HOMER simulation software in
order to model both the size of the system as well as the
economics of it. Then out of the multiple solutions provided
by HOMER, the most optimized solution was chosen. The
system given in the figure below shows the following
components;
1. Solar PV Array
2. Battery Bank
3. Electric Cars modeled as load
4. Converter.
Figure 4: System Design in Homer
B. Load Requirement
Load requirement of the system is chosen by the no. of
vehicles and the power each one of them requires to come to
a full charge.
No. of Vehicles = 10
Power Rating = 7.7 kW
Time Taken by each vehicle to charge to 100% = 8.8 hours
(9 hours)
Hourly Load = No. of vehicles*power rating*1 hour =
10*7.7*1 = 77 kWh
Daily Load = No. of Hours*Hourly Load = 9*77 = 693 kWh.
Peak Load = 77 kWh
Figure 5: Daily Load Profile
Figure 6: Seasonal Load Profile
C. Array Size
 CanadianSolar MaxPower CS6U-340M
 Efficiency (%): 17.49
 Capital Cost per panel: $279.50
 Replacement Cost per panel: $279.50
 O&M Cost per panel: $10.00
D. Battery Size
Tesla Power Wall 2.0. Powerwall is a battery that stores
energy, detects outages and automatically becomes your
energy source when the grid goes down.
 Nominal Voltage (V): 220
 Nominal Capacity (kWh): 13.2
 Nominal Capacity (Ah): 60
 Roundtrip Efficiency (%): 89
 Maximum Charge Current (A): 31.8
 Maximum Discharge Current (A): 31.8
 Capital Cost per battery: $6500
 Replacement Cost per battery: $6500
E. Optimum Solution
Based on the components chosen, HOMER simulation
software gave us the following optimum solution;
Table 3: Possible Solution for our Given Project in the
presence of the Grid
Architecture/CS6U-340M (kW)
1745.84375
Architecture/TeslaPW2
52
Cost/NPC ($)
1309774
Cost/COE ($)
0.4006328
Cost/Operating cost ($/yr)
37424.89
Cost/Initial capital ($)
825963.3
System/Ren Frac (%)
100
System/Total Fuel (L/yr)
0

Presented at 30th IEEE NECEC Conference. November 18, 2021 St. John's, NL
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CS6U-340M/Capital Cost ($)
487963.3
CS6U-340M/Production (kWh/yr)
2155745
TeslaPW2/Autonomy (hr)
23.77143
TeslaPW2/Annual Throughput
(kWh/yr)
17259.96
TeslaPW2/Nominal Capacity (kWh)
686.4
TeslaPW2/Usable Nominal
Capacity (kWh)
686.4
Architecture/CS6U-340M (kW)
1745.84375
Architecture/TeslaPW2
52
Cost/NPC ($)
1309774
Cost/COE ($)
0.4006328
F. Array Power Output
Figure 7: Monthly Electric Production
G. Excess Energy
After the calculations done by the HOMER simulation
software, the excess electricity being generated is as
following. This energy can be used to both increase the
battery backup by a few more days or could be used for
loads like street lighting.
Table 4: Excess Energy in the System
Quantity
kWh/yr
%
Excess Electricity
1,887,630
87.6
Unmet Electric Load
53.1
0.0210
Capacity Shortage
247
0.0978
VI. SYSTEM DYNAMIC MODELING
After this, we designed a simulation of the system in
Simulink MATLAB and observed the dynamic behavior of
the system.
Figure 8: Modelled System in MATLAB
Now if we take a look at the PV part of the system it
consists of the following;
Figure 9: PV Model
The battery model is as follows;
Figure 10: Battery Model
The inverter model is as follows;
Figure 11: Inverter Model
Finally, the load of the system looks like following;
Figure 12: Load Model
VII. SYSTEM CONTROL DESIGN
A. Charge Controller
A solar charge controller is mostly used to manage the
power going in and out of the battery bank from the solar
array. By controlling this flow of power, a charge controller
helps ensure that deep cycle batteries are not overcharged at

Presented at 30th IEEE NECEC Conference. November 18, 2021 St. John's, NL
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daytime and power does not run in reverse direction into the
solar panels at night time. The charge controller used in our
system is a DC-2-DC buck boost converter.
B. Buck-Boost Converter
The main reason a buck-boost converter is used in a
system is to receive an input DC voltage but output a
different value of that voltage. This is done either by
lowering or boosting the voltage of the system as required.
A buck-boost converter is designed by combining the
functionality of both buck converter and boost converter.
Following is the model of buck-boost converter used in our
system;
Figure 13: Buck-boost Converter
In figure 22, the duty cycle was generated by using the
following circuit;
Figure 14: Duty Cycle Generator
C. Perturbation and Observation (P&O) Algorithm
The algorithm used in the MATLAB block is
Perturbation and Observation (P&O) algorithm. This
algorithm works by perturbing the operating point of our
system thus causing the terminal voltage of the PV array to
fluctuate around the MPP voltage. It then measures the
current and voltage to make the decision or increasing or
decreasing the duty cycle. Given below is the algorithm
diagram for P&O method;
Figure 15: P&O Algorithm
The following code was used in the MATLAB function to
generate the duty cycle signal through Perturbation and
Observation (P&O) algorithm.
function d = dutyCycle(Vpv, Ipv)
%# code gen
persistent Vpre Ppre dpre
if isempty(dpre)
Vpre = 10;
Ppre = 20;
dpre = 0.3;
end
Ppv = Vpv*Ipv;
DeltaD = 0.01;
if (Ppv == Ppre)
d = dpre;
else
if(Ppv > Ppre)
if(Vpv > Vpre)
d= dpre + DeltaD;
else
d = dpre - DeltaD;
end
else
if(Vpv > Vpre)
d = dpre - DeltaD;
else
d = dpre + DeltaD;
end
end
end
Vpre = Vpv;
Ppre = Ppv;
dpre = d;
D. Control Logic
The technique used in this system is very much similar to
hill climb method as we measure the values of power and
voltage on the power vs. voltage graph and determine the
location of the system to find out if it is on the LHS or RHS
of the graph shown in figure below.
Figure 16: Power vs Voltage Diagram for PV
So there are four basic situations in this system;
1. When power is increasing and voltage is increasing
2. When power is decreasing and voltage is
decreasing
3. When power is increasing but voltage is
decreasing
4. When power is decreasing but the voltage is
increasing
In the first two situations, the system is on the LHS of the
graph and thus the duty cycle needs to be increased while in
the second two situations, the system is on the RHS of the
graph and thus the duty cycle needs to be decreased.

Presented at 30th IEEE NECEC Conference. November 18, 2021 St. John's, NL
6
VIII. RESULTS
Upon the simulation of the system, following results
were obtained;
Figure 17: Battery SOC during charging and
discharging cycle
Figure 18: Battery Current during charging and
discharging cycle
Figure 19: Battery Voltage during charging and
discharging cycle
Figure 20: PV System Ouput Current
Figure 21: PV System Output Voltage
IX. DISCUSSION
As it can be seen through our results, our PV generation
follows what is known as a bell-shape/bell-curve behavior.
This is due to the sunlight behavior which is zero in the
beginning and end of the day and slowly increases during the
daytime. This PV generation affects the behavior of our
entire system as PV is our main source of energy.
As seen in figure 26, 27, and 28, during the peak sunlight
hours when there is ample electricity being generated, the
battery voltage is at its highest. The state of charge of battery
shows a constant behavior and similarly no current is flowing
through the batteries.
However, this behavior changes in the begging and end
of the day when there is no sunlight and ultimately no Power
generation through PV. At this time, the state of charge of
the battery can be seen depleting and the current is at its
highest. This behavior is typical of any solar PV powered
system with a battery backup.
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