VISVESVARAYA TECHNOLOGICAL UNIVERSITY
Jnana Sangama, Belagavi – 590 014
TECHNICAL SEMINAR REPORT ON
DESIGN OF A NEW TYPE OF CHARGING STATION FOR SOLAR
ELECTRIC VEHICLE
A Seminar report submitted in partial fulfilment of the requirements for the award of
Bachelor of Engineering in Electronics and Communication Engineering of Visvesvaraya
technological University, Belgaum.
SUBMITTED BY:
Mr. LAKSHMINARAYANA D P
(USN:1GG17EC008)
UNDER THE GUIDANCE OF
Prof. Noor fathima
Assistant Professor
Dept. Electronics and Communication
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
ENGINEERING
GOVERNMENT ENGINEERING COLLEGE
BM ROAD, RAMANAGARA-562159
2020-2021
Dept. of E&C, GEC Ramanagara
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DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
GOVERNMENT ENGINEERING COLLEGE
Ramanagara-562159
CERTIFICATE
Certified that the seminar entitled “Design of a new type of charging station
for solar electric vehicle”
survey on recent research trends has been
successfully presented at Government Engineering College,Ramanagara
by LAKSHMINARAYANA D P , bearing 1GG17EC008, in partial
fulfilment of the requirements for the VIII semester degree of Bachelor of
Engineering
in
Electronics
and
communication
Engineering
of
Visvesvaraya Technological University, Belgaum during academic year
2020-2021. It is certified that all corrections/suggestions indicated have
been incorporated in the report. The seminar report has been approved
as it satisfies the academic requirements in respect of seminar work for
the said degree.
Signature of Guide
Signature of Examiner
Name:
Designation:
Signature of Head of the Department
Dept. of E&C, GEC Ramanagara
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DECLARATION
I, LAKSHMINARAYANA D P ( 1GG17EC008 ) student of VIII
semester BE, in Electronics and Communication, Government
Engineering College,Ramanagara hereby declare that the seminar
entitled “Design of a new type of charging station for solar electric vehicle”
has been presented by me and submitted in partial fulfilment of the
requirements for the degree of Bachelor of Engineering in Electronics
and Communication of Visvesvaraya Technological University, Belgaum
during academic year 2020-2021.
Date:
Place: Ramanagara
Dept. of E&C, GEC Ramanagara
Name: LAKSHMINARAYANA D P
USN: 1GG17EC008
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ACKNOWLEDGEMENT
The satisfaction and euphoria that accompany the successful completion of any task
would be incomplete without the mention of the people who made it possible,
whose constant guidance and encouragement crowned the efforts with success.
I would like to profoundly thank Government engineering college,Ramanagara for
providing such a healthy environment for the successful completion of Seminar
work.
I would like to express my thanks to the Director Principal Dr. G.Pundarika for their
encouragement that motivated me for the successful completion of Seminar work.
It gives me immense pleasure to thanks Dr. Revanna C.R Head of the Department
for his constant support and encouragement.
I would like to express my deepest sense of gratitude to my Seminar guide Prof.
Deepa V P, Department of Electronics and Communication Engineering for his
constant support and guidance throughout the Seminar work.
I would also like to thank the Seminar Coordinator Prof.Noor fathima, Department
of Electronics and Communication Engineering and all other teaching and nonteaching staff who has directly or indirectly helped me in the completion of the
Seminar work.
Last, but not the least, I would hereby acknowledge and thank my parents who have
been a source of inspiration and also instrumental in the successful completion of the
seminar work.
LAKSHMINARAYANA D P
1GG17EC008
Dept. of E&C, GEC Ramanagara
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CONTENTS
1. INTRODUCTION
2. ELECTRIC VECHILES
3. PROPOSED SOLUTION
4. SUMMARY AND CONCLUSION
5. REFERENCES
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CHAPTER 1
INTRODUCTION
According to the MIT Technology Review, 1.5 billion people on this Earth currently lack
electricity and this in the 21st century. Nearly seventy percent of the population of subSaharan Africa, approximately 600 million people, is without electrical power. Many people
on Indian reservations in the United States also lack access to electricity.
While such communities can have shared vehicles, these must often be driven to far away
locations in order to be refueled, and additional costs are incurred with each refueling.
The emergence of commercially available electric vehicles and reduced costs of solar panels
and wind turbines offers solutions to both of these problems, especially in regions rich in
solar energy, where electric vehicles or plug-in hybrids can be charged using an off-grid, lowcost solar charging station. Such a simplified transportation system does not require fuel to be
obtained or delivered from far-away places, and does not incur additional fuel costs once
installed. If the vehicle and charging station are obtained by federal grant or through a
charitable organization, the costs to the community are minimal.
1.1 BACKGROUND:
In developed nations, the electric car is often viewed as an adult toy – a novelty rather than a
necessity. In underdeveloped regions, on the other hand, a low-cost transportation system
based on solar or wind energy could significantly impact the entire economy.
At the end of 2013, about 36 GW (peak) of solar photovoltaic (PV) systems were installed in
Germany. This corresponds to about 150 million solar panels. Due to limited sunlight and
low solar panel efficiency, one megawatt of installed solar power in Central Europe collects
approximately one giga watt-hour of electricity annually.
While the “global annual horizontal irradiation” in Germany is about 1000 kilowatt-hours per
square meter, it is 2.5 times higher in most areas of Africa – about 2500 kWh/m2.
In addition, the shadow cast by a solar panel supplies some shade, and therefore “cooling
power”. While this is not needed, or even desired, in northern countries, the added feature of
shadow generation is welcome in the deserts of Southwestern USA or in Africa. Assuming
the cooling effect of the shadow produced by the solar panel is between 500 and 1000
kWh/m2, a solar panel installed in Africa is then 3 to 3.5 times more effective than in Central
Europe.
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This solar panel cooling effect can also be critical to the adoption of electric vehicles in very
warm areas, since the lifetime and efficiency of lithium-ion batteries are negatively affected
by heat. Parking electric vehicles under solar charging panels can extend the lifetime and
performance of electric vehicles in underdeveloped nations, thereby reducing overall costs.
Batteries have become the popular form of electrical energy storage in EVs. The evolution in
city transportation has boosted over the last few decades which in turn increased the growth
of societies and industry. Since battery is a commonly used device for storage of energy,
calculation of Status of Charge plays a vital role in the future. Nowadays, vehicles are
essential in the day to day life and for industrial use as well. Sufficient effort is being done to
withdraw the combustion engines by electric motors. Due to the increase in carbon dioxide
(CO2) caused by the industries and transportation, the Kyoto treaty was signed. This treaty
was aimed to reduce the level of CO2 and has boosted the findings for new cleaner energy
solutions. As a finding, Electrical Vehicles (EVs) appeared as a solution to reduce CO2
emissions. Electric Vehicles are increasing day by day across the globe.
The demand for conventional energy like coal, natural gas and oil is raised, so that the
researchers forced towards the development of renewable resources or non-conventional
energy resources. In the last couple of years, there has been a lot of discussion around the
prices of fuel apart from the deregulation of petrol and fossil fuel prices. Moreover, these
threats of disruption of supplies have brought the focus on to alternate drive train
technologies. In 1800s electric vehicle had led on the road .while Robert Anderson, a British
inventor introduces first crude electric carriage .the potential for a alternative technologies in
automobiles such as electric vehicle, which is first discovered by William Morrison, a
chemist in the US.
When the number of Electric vehicles is increasing, there is a need to implement Electric
Vehicles Charging system in parking systems.
EVs bring benefits to city services and provide indemnity for the viable energy sources
intermittency. This new method is effective and more relevant owing to the fact that most of
the electric vehicles are halted on an average of 91-95 percentage of their usage period, and
most of the Electric vehicles are parked at home amid 9 pm and 6 am. IoT makes smart grid
to contribute the information between multiple users and thus amplifies connectivity by the
help of infrastructures. Cloud storage is used for the data storage where the data is send
through Internet gateway.
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CHAPTER 2
ELECTRIC VEHICLES
More and more plug-in electric (hybrid and non-hybrid) cars are coming to the market.
Currently, these include the 2seat SMART Electric Drive, the Ford Focus Electric, the Chevy
Volt, the VW E-Golf, the Nissan Leaf, the BMW i3, the Opel Ampera, the Toyota Plug-in
Hybrid, the Tesla, the Honda Civic Hybrid, and others. Most of these cars are charged by the
electric grid. However, replacing gasoline with electricity from a national grid does not
necessarily lead to a significant reduction in carbon footprint since, in the USA at least, more
than half of the nation’s grid power still comes from coal, oil, and natural gas.
A main advantage of an electric motor is its higher efficiency compared to a combustion
engine. Let’s look at the fuel costs. The EPA/DOT fuel economy for the Smart Electric
Drive (according to the data sheet) is 107 MPGe, or 32 kWh per 100 miles. MPGe means
“miles per gallon of gasoline equivalent” and is used by the “...U.S. Environmental Protection
Agency to compare energy consumption of alternative fuel vehicles, plug-in electric vehicles,
and other advanced technology vehicles with the fuel economy of conventional internal
combustion vehicles expressed as miles per U.S. gallon”.
Since a gallon of gasoline contains approximately 33.7 kWh of energy, the following
numbers are obtained for the SMART car:
• SMART-for-Two, 2008, Gasoline Engine: 38 miles per gallon, or $0.10 per mile (assuming
a fuel cost of $3.80 per gallon);
• SMART ED (Electric Drive), Grid-Tied: 107 MPGe; 0.32 kWh per mile, or ~$0.05 per mile
(assuming a cost of electricity of $0.16 per kWh);
• SMART ED, Sun-Car, Off-Grid, after pay-off of charging station: $0.00 per mile
The gasoline engine produces about 8.9 kg (19.6 lbs) of CO2 for every gallon of gasoline, or
every 38 miles of driving. Thus, about half a pound of CO2 is produced for every mile
driven. This is reduced to 0 pounds per mile if an electric vehicle is powered by solar energy.
In this case, CO2 emissions are reduced by about 25,000 pounds (more than 11 metric tons)
for every 50,000 miles driven. Other advantages of electric vehicles include their more
simple construction compared to gas-powered cars, (e.g., oil changes are not necessary), and
features such as regenerative braking, which leads to a further increase in efficiency.
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2.1 CHALLENGES:
The main problems of electric vehicles are the limited charge content (miles per charge) and
the high price of their batteries. A great deal of research is going on worldwide to improve
both parameters. Most electric cars have lithium ion batteries that may experience
temperature-related problems or failures in very hot areas such as Arizona or Africa. Clever
cooling solutions will no doubt be developed in time. Further, several advances and
improvements in battery technology are on the horizon.
For example, nanostructures are eventually projected to lead to a five-fold increase in battery
life. These improvements are, however, several years out. Challenges are also introduced by
battery charging procedures.
There are basically two technologies:
1. Conductive charging (which is used in most cases)
2. Dynamic wireless charging
1. Conductive charging system:
Conductive charging requires a physical connection between the electronic device's
battery and the power supply. The need for a metal-to-metal connection between the
charger and the device requiring charging is one of the main drawbacks of this
method. To accomplish this without the use of physical cords connected to wall outlets,
special attachments are made from electronic devices which are fitted with technology
that can detect when the device makes connection with the power source, often a
charging base. Conduction based wireless accessories may include changeable backs for
cellular phones, special sleeves and attachable clips.
The electronic devices, fitted with these accessories, are placed on a charging base. The
base can detect when a compatible device has been placed on it and begin the battery
charging process. These charging bases are usually designed to be able to distinguish
between human and metal contact so that there is no risk of electrocution. For example,
the company Energy square has developed its own technology based on a conduction
process named Power by contact. It provides an alternative way for consumers and
professionals to refill their everyday's use devices, such as Laptops and smart phones,
with the advantage of a safe recharge without any power loss.
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2. Dynamic wireless charging system:
Dynamic wireless charging system allows the vehicle to charge in real time while in
motion, which also allows the reduction of the overall battery capacity in the vehicle. This
provides the benefit of reducing overall vehicle cost and reduced charging times.
Dynamic wireless charging systems are a part of wireless power transfer (WPT)
technology, where power can be transferred from one circuit to another circuit without
any physical contact or wiring. The power transmitter portion is composed of a power
source and coil, where the power source is generated into an electromagnetic field as it
enters through the coil. The power receiver portion, which consists of another coil, will
convert the received electromagnetic field into usable energy that can power another
source.
Dynamic Wireless Charging of Electric Vehicle approach revolutionizes the changes in
Electric Vehicle Industry. Dynamic Wireless Charging of Electric Vehicle reduces the
cost and size of the battery, thereby reducing the cost of electric vehicle.
2.2 CHARGING TIMES:
In general, there exist three systems that yield different charging times:
1. Level 1 charging: 120 VAC, 60 Hz.
The slowest from of charging. These charging stations use a normal 120-volt
connection, which uses any standard household outlet; there are no extra costs here.
The downside is that charging times can be slow. Many electric vehicle owners will
likely find that they typically don’t deplete more of the battery than can be
replenished overnight using a basic 120V connection. This set up provides between 25 miles per hour.
2. Level 2 charging: 240 VAC, 60 Hz.
These EV chargers use a higher-output 240-volt power source, like the one that you
plug your oven or clothes dryer into. Charging times are much faster than with a
Level 1 EV charging station. A Mercedes B Class 250e, for example, can take 20
hours to fully charge (87 miles of range) with a standard 120-volt charging station. A
240-volt Level 2 charger can fully charge a 250e in three hours. Most EV owners find
they want a faster charge and upgrade to a Level 2 charging station soon after buying
their electric car.
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A high-speed charging station at home is much more convenient and also can add
value to your home’s resale value. Having a Level 2 EVSE at home is ideal because
most EV owners find they do the majority of their charging at home.
For example, Level 1 home charging simply won’t work for anyone who drives long
distances regularly and doesn’t have the time or opportunity to recharge their car
during the day. Upgrading to a Level 2 charging station for that owner becomes a
necessity, especially if the car is fully electric and there aren’t any public charging
stations at the workplace or nearby.
One advantage of the longer range cars is that they should seldom use all their charge
in a single day’s commute. With ranges that top 200 miles and average daily
commutes of less than 40 miles, it should only be a matter of topping off the battery at
night, which can typically be done in a couple hours.
3. Level 3 charging: 400 VDC, 0 Hz.
These fast-charging devices use very high voltage and can add 90 miles of range to an
EV in just 30 minutes in some cases. These chargers, however, are extremely
expensive, costing tens of thousands of dollars, and routinely using a Level 3 charger
can ultimately hurt your car’s battery, so we wouldn’t consider one for home
installation; they are also cost prohibitive for most EV owners.
Range added per hour of charging
Fig 1: Levels of charging station.
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The ability of electric vehicles to reduce greenhouse gas emissions is often overstated,
especially in northern industrialized nations, where the available solar energy is limited.
In hot, equatorial regions, however, solar panels are much more effective and collect more
energy, making this a different case entirely.
In these areas, the environmental manufacturing costs associated with electric vehicles,
lithium-ion batteries, and solar panels are quickly negated.
Moreover, better and lower-cost solar cells can be expected in the future. A Boston-based
company, 1366 Technologies, claims they can make solar cells at less than half the cost of
current cells. Their starting material is molten, fluid silicon.
While it may be obvious, one of the reasons why industrial nations are located in northern
regions is simply because it is easier to work in cooler climates. Many underdeveloped
nations are located in southern or equatorial and large desert areas. These locations receive
the most solar energy. Living conditions in parts of Africa would appall many. For example,
in an eastern African country close to the Equator, there is a village with about 700-800
inhabitants living in about 250 grass covered huts.
The latter have no flowing water and no electricity. There are no railway or ship connections,
no gasoline cars, no taxi or bus services, no gas stations, no electrical grid, etc. Similar
situations can be found in many southern developing countries.
The introduction of a few electric cars operated with off grid solar energy could become a
real game-changer with relatively little investment capital. The cost of the off-grid charging
station can be a fraction of the price of an electric vehicle, maybe 10-15%. Communityshared electric vehicles could provide transportation for an area inside a 60-100 mile radius.
No expensive infrastructure (gasoline pump stations, tankers, etc.) is necessary.
Organizations such as Power Africa or the U.S. Africa Development Foundation (ADF) could
donate a few electric cars. This system would also fit nicely into the ADF’s so-called
“Off-Grid Energy Challenge”.
“Off-Grid Energy Challenge”: The Off-Grid Energy Challenge is led by the U.S. African
Development Foundation (USADF) to develop, scale-up or extend the use of proven
technologies for off-grid energy to reach communities not served by existing power
grids.
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Through the Challenge, USADF and its partners, including All On, General Electric
(GE), and Power Africa support energy entrepreneurs in 9 countries across the continent,
including Ethiopia, Ghana, Kenya, Liberia, Nigeria, Tanzania, Rwanda, Uganda and
Zambia. To date, USADF has funded over 75 African energy entrepreneurs, totalling an
investment of $7 million in off-grid energy solutions.
The Off-Grid Energy Challenge awards grants of up to $100,000 each to African
enterprises providing off-grid solutions that deploy renewable resources and power
local economic activities. Challenge winners will have near-term solutions to power the
needs of productive and commercial activities, including agriculture production and
processing, off-farm businesses, and commercial enterprises.
The status of solar energy use in Africa is described by the following headline: “Uganda
slow at seizing solar energy opportunity amid high energy costs” .However, help is on the
way. For example, the U.S. government plans to spend $7 billion to electrify sub-Saharan
Africa in the next 5 years.
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CHAPTER 3
PROPOSED SOLUTION
The implementation of conventional transportation systems requires a lot of capital that
developing countries generally do not have. Even in industrial nations such as the U.S., most
consumers still opt for gasoline-powered vehicles. This is due in part to the higher cost of
electric vehicles and their relative novelty, which leads to the sense that electric vehicles are
still somewhat unproven and risky. This sentiment is borne by the facts: In 2013, 15.5
million cars were sold in the U.S., but only 96,552 of these were primarily electric vehicles.
However, due to the abundance of solar energy in hot areas, the combination of electric cars
and off-grid operated solar charging.
Stations could provide an almost ideal solution to the existing transportation problem in these
areas. Compared to conventional on-grid charging, this system has the advantage of reducing
the carbon footprint to almost zero once installed.
3.1 THE “SUN-CAR KIT”:
MTECH Laboratories has developed and tested a low-cost, off-grid, easy-to-install solar
charging station prototype called the “Sun-Car Kit”.
A simplified block diagram is shown in Fig 4 and a photograph of the initial assembly in
Fig 2. Four 255watt (peak power) solar panels (1020 Wpk) from Solar World were used.
This unit can be used at any workplace or close to the home if space is available.
The solar panels can either be mounted on the ground as shown in Fig 2, or on a scaffold-like
structure under which the electric vehicle could be parked during charging, as shown in
Fig 3.This also serves to protect the car and its batteries from the sun and to keep them cool.
Excess solar energy, for example when the car is not being charged, is stored in a battery
bank. In this prototype, 4-6 deep-cycle marine batteries (type 27) were used.
The batteries also provide excess power while charging the SMART car with about 900 W.
A charge controller is inserted between the solar panels and the batteries in order to protect
the latter. The 24-VDC system feeds a 2kW pure sine wave inverter that provides 120 VAC
at 60 Hz.
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For a three-month period, a SMART Electric Drive vehicle (model “For-Two”) was charged
strictly from the prototype solar charging station, without any power delivered by the grid.
Depending on the Upstate New York weather and cloud cover between August and
November (2013), 1-4 kWh could be collected each day.
One kWh translates into about 3.2 miles of operation. More solar panels could, if necessary,
be added. The system could also be combined with wind turbines to further enhance energy
generation.
Workplace charging stations benefit from the fact that they collect solar energy 8-12 hours
per day, even when cloudy. Until power grids are energized by completely renewable energy
sources, the proposed off-grid charging system provides an attractive solution to the
powering of electric cars as far as carbon footprint reduction and costs are concerned.
Fig 2: Working prototype solar electric vehicle charging station set up at MTECH’s facilities
in Ballston Spa, NY
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Fig 3: Artist’s rendering of one style of solar charging station proposed
3.2 SOLAR CHARGING STATION SYSTEMS:
The combination of solar energy and electric vehicle (EV) charging is the key in drastically
reducing our dependence on fossil fuels. Electricity comes from a variety of sources and
it’s crucial that electric vehicles will be powered by renewable. Electric cars are becoming
immensely popular and coming years we expect nearly anyone who owns a solar energy
system will install a solar charging station at its home. For this to happen we’ll need a
fundamental change in how we think about refuelling our cars and a natural evolution of our
energy infrastructure.
Components needed for a solar charging station
1. EV charger
2. Solar panel array, installed on roof, ground or canopy
3. Battery energy storage system (ESS, in case of an Off-Grid Solar energy charging
station)
4. Solid foundation, in case of a stand-alone solar charging canopy (Often used: a steel
base plate that functions as ballast, so no foundation is required, simplifying the
installation).
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PV module
Power grid
Intelligent control
System
DC power
distribution
unit
Photovoltaic power
Intelligent control
system of
charging station
Charging
interface
Electric
vehicle
Generation system
Battery pack
Energy storage
System
Fig 4: Structure of solar charging system
PV module: A PV module is an assembly of photo-voltaic cells mounted in a frame work for
installation. Photo-voltaic cells use sunlight as a source of energy and generate direct current
electricity.
DC power distribution unit: Power Distribution Unit, is a device used to control and
distribute electric power. The most basic form of a PDU is a large power strip without surge
protection.
This is designed to provide standard electrical outlets for use within a variety of settings that
don't require monitoring or remote access capabilities. PDUs are available in both AC and
DC models to match the power in use at different kinds of sites.
DC PDUs are built just like their AC-power counterparts, except for their output current. DC
power distribution units are designed to provide electric current in the Direct Current format
that many rack-mounted devices use.
Power grid: A power grid is a network of power lines and associated equipment used to
transmit and distribute electricity over a geographic area.
Charging interface: A charging standard defines the mating connector that is used
for charging as well as the communication protocol used between the vehicle and the charger.
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Battery pack: A battery pack is a set of any number of (preferably) identical batteries or
individual battery cells. They may be configured in a series, parallel or a mixture of both to
deliver the desired voltage, capacity, or power density.
Intelligent control system of charging station: A charge controller, charge regulator or
battery regulator limits the rate at which electric current is added to or drawn from electric
batteries. It prevents overcharging and may protect against overvoltage, which can reduce
battery performance or lifespan and may pose a safety risk.
3.3 SYSTEM WORKING PRINCIPLE:
Solar grid connected energy storage system can be integrated photovoltaic module, DC
power distribution equipment, storage battery, charging station intelligent control system,
charging interface and power grid interface, etc., the specific system structure as shown in
Fig 4.
With plenty of sunshine during the day and PV systems send DC after DC distribution unit
confluence, by charging station, intelligent control system to control the charging and
discharging control module to the battery storage, again through the bi-directional inverter
module connected to the charging interface for electric vehicle power supply and excess
capacity by grid connected into the power grid.
At night or on cloudy weather when the storage is inadequate, grid through the intelligent
control system to supply power to the electric car, also through the intelligent control system
in the bi-directional inverter module for storage battery power supply storage, so as to
effectively guarantee the charging station continuous and stable operation.
3.4 SOLAR CHARGE CONTROL CIRCUIT:
Specifications
 Reverse battery protection: Control shuts down if battery is inadvertently
connected reverse.
 Voltage regulation: 5mV (voltage change no load to full load)
 Maximum current:3A (current limiting provided by solar panel characteristics)
 Max solar panel rating (6V): 22W (open circuit solar panel voltage = 9 to 10V)
 Output voltage range: 4.5 to 15V (continuously adjustable)
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This solar charge control combines multiple features into a single design: 3A current rating,
low dropout voltage (LDO), range of voltage adjustment (accommodates 6 & 12V lead-acid
batteries), reverse polarity protection, low parts cost and low parts count (14 components).
High performance is attributed to the application of the common LM358 op amp and TL431
adjustable shunt voltage regulator.
Fig 5: Solar Charge Control Circuit Schematic
Circuit Operation:
R1 biases D1, the voltage reference diode. The 2.5V reference from D1 is compared with
voltage feedback from the resistor divider. The op amp does all within its power to keep these
two voltages identical. The ratio of R3 /R2 controls the proportional gain, and C1 is a
compensation capacitor that blocks DC feedback, but responds to changes in output signal
thus maintaining stability (prevents oscillation).
Zener D2 prevents overvoltage at the gate of Q1—R4 limits op amp output current when D2
is conducting. C1 is the positive rail bypass capacitor.
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D3 prevents battery voltage from appearing across the solar panel and prevents unnecessary
battery discharge when the solar cells are not generating power.
When the feedback voltage from the wiper of R6 drops below 2.5V, the output of U1A
moves in the negative direction thus turning Q1 on. The increased current out of Q1 causes
the battery voltage to increase and increases the voltage at the wiper of R6 until it is equal to
the reference voltage.
It may seem like a waste to use a dual op amp when only a single is required, but the LM358
remains the least expensive and most available device. It also has an undocumented feature
that provides reverse battery connection.
When the battery voltage is reverse, the non-inverting input of U1 is driven below the
negative rail (common)—when this happens, the output of the op amp swings to the positive
rail thus turning off Q1 and protecting the circuit against this potentially damaging condition.
While this ‘malfunction’ is perhaps well known in the engineering community, the
application of this as a circuit trick is new to the world.
3.5 SYSTEM FEATURES:
Universal: The solar charging station system of intelligent control system with automatic
analysis ability to identify various types of battery system and various voltage levels, and all
kinds of pure electric vehicle power battery system to achieve charging characteristics
matching, for different battery charging, full foot in public places and all kinds of electric
vehicle charging interface, a charging criterion and interface protocol standard general use.
Intelligent: Intelligent reflected in the system for intelligent power distribution, charging and
discharging intelligent and intelligent detection and measurement. Intelligent discharge can
realize non destructive charging and discharging of the energy storage battery through
optimized intelligent charging and discharging technology, monitoring battery state of charge
and discharge, to avoid too charge and discharge phenomenon ,to accomplish the battery fault
automatic diagnosis and maintenance, so as to extend the battery life and energy saving.
Convenience: Users can directly through the charging station, intelligent control system of
liquid crystal touch screen for charging type selection, query volume charging, charging the
cost of query, network information query, print invoices, both convenient and humanized.
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3.6 COSTS:
The cost of one kilowatt (installed power) obtained from the sun has dropped more than 100
times from $76,670/kW in 1977 to about $740/kW in 2013.
Assuming this power is
available for 8 hours of the day on average, a 1-kW solar array should yield around 8 kWh
per day – about 25 miles per day or just over 9,300 miles per year for the SMART Electric
Drive (3.2 miles/kWh). Using Uganda as an example with its fuel cost of $5.40/gallon, the
equivalent annual gasoline cost at 38 mpg is around $1325.
To calculate gas prices and gas consumption using information about:

Fuel efficiency (car consumption for 100km or miles per gallon)

Distance you are planning to travel (or cities which you intend to visit on your
journey)
By using car consumption and travel distance, our tool shows you approximately how much
gasoline (petrol) your car will consume, an approximate price and also estimates how much
will your car depreciate during that trip.
Assuming the complete charging station (including storage batteries, solar panels, inverter,
and so on) can be purchased for under $3,000, the solar charging station could pay for itself
in about two years.
In the third year and beyond, fuel costs would be zero. The cost of solar panels will
certainly continue to drop. In addition, there is a worldwide effort to reduce the cost of
lithium-ion battery technology, which will lead to the availability of lower-priced electric
vehicles in the near future. On the other hand, the economic benefits of giving remote
populations a means of travelling to nearby cities should be considerable.
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3.7 OTHER CONSIDERATIONS: THE “2/5 SYSTEM”:
A vast amount of energy is unnecessarily wasted every day. According to the US Bureau of
Transit Statistics, there were around 251 million registered passenger vehicles in the United
States in 2006. Of these, about 99 million were SUVs and trucks.
Yet almost all of these 251 million cars are designed for transporting 5 to 7 passengers and
therefore weigh about 3 to 4 thousand pounds.
The average American family owns two such cars. This arrangement can be called the “5/5
System.” But most people never consider the fact that the vast majority of all trips (estimated
at 98% to 99%) are made with only one or two passengers.
Thus, hundreds of millions of miles are driven each day by only one or two people (100-400
lbs of “cargo”) in automobiles designed for 5 to 7 people (3,0004,000 lbs of vehicle).
The 2-seat SMART “Sun-Car-Kit” supports the so-called “2/5 System”. The idea is simple:
Instead of owning two heavy and inefficient cars designed to carry an entire family, the
average family would own one conventional 5- to 7-seat car and one small and fuel-efficient
two-seat car weighing half as much (hence the term “2/5 System”).
The small car would be used for daily commutes and the larger one for family excursions.
This will drastically reduce the fuel consumption for personal transportation (by as much as
an estimated 30%50%).
Based on their size and weight, smaller plug-in electric vehicles, in theory, require less
charge to run a given number of miles, especially in suburban or urban settings.
Thus, the solar charging station will provide greater mileage to smaller cars, especially 2seaters such as the SMART Electric Drive. The availability of this 2seat electric car (and
others are sure to follow) enables the 2/5 System.
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CHAPTER 4
SUMMARY AND CONCLUSIONS
In 2013, the U.S. populace bought 160 times more gasoline/diesel cars than electric cars .
This will no doubt change dramatically as electric cars become more ubiquitous, are proven
through long periods of ownership and use, and are improved in both cost and performance.
The range limitation will also become less of a factor as battery performance is enhanced.
This opens the door to off-grid charging stations.
MTECH’s “Sun-Car Kit” is a low-cost, easy-to-install, off grid solar charging station for
electric vehicles, which can be easily expanded by simply adding more solar panels.
Significant savings in fuel and/or electricity costs and a reduction of CO2 emissions are
possible. The system is especially well-suited for work-place commuting, wherein electric
vehicles could be charged by an on-site, off-grid charging station during working hours,
yielding enough charge for the drive home. Because of its low cost and simplicity, the
demonstrated Sun-Car Kit could provide a tremendous opportunity for all hot areas with
underdeveloped or non-existent personal transportation systems. Even in developed nations,
farms and rural areas could benefit from the technology. The solar electric vehicle charging
station is also an excellent teaching tool for high-school and college students, who need to
understand the concepts of volts, amperes, watts, kilowatt-hours, miles per gallon, MP Ge,
and the intricacies of solar collectors, charge controllers, batteries, kilowatt inverters, and of
energy and transportation systems in general. This idea is certainly not new. Solar charging
stations for electric vehicles already exist in places such as New Mexico and Arizona,
Mississippi, and even Maine. However, the concept is especially promising in developing
nations and areas. The introduction in these regions can have a profound effect in raising the
quality of life for vast populations around the world, which, in turn, will bring new
educational and economic possibilities to millions. This can only benefit the world as a
whole. Comply with the rise of new energy vehicles, the solar energy grid storage energy
type charging station system in full consideration of the light environment, such as a variety
of environmental factors based on the advanced design concepts, a collection of new energy
in the field of photovoltaic power generation, energy storage, grid, charging etc., many new
technologies, fully embodies the its scientific rationality, economy, security and other
characteristics, for the electric vehicle charging station construction provides an innovative
integration solutions.
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CHAPTER 5
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