ABSTRACT
Solar
energy can be used to charge laptop batteries, solar panels are used for
conversion of sun light to electrical energy, by using photovoltaic phenomenon.
Design of solar laptop charger contains voltage regulator that is used to set
the desired output voltage level, also voltage regulator remove ripples.
Charged controller circuitry implemented in design for increasing the battery
life. As battery performance reduced if it is continue to charge even charging
not required so charged controller is used to keep on check on the battery
voltage. So charged controller circuitry enhance the life of battery. In
addition, keep it save from any damage. Battery is the part of system that is
used to save energy, as the energy may not be used as it is produced so for
storing electrical energy, battery is used. This laptop charger is portable. So
mostly this application can be used for charging laptop during researches in
the area such as seas, forest, desert where ac voltage is not available. It can
also use as for daily use for charging of batteries.
Dedication
We
would like to dedicate this project to all the scientists that give their
efforts to promote the usage of solar energy including Alexander Edmond
Becquerel who observed the photovoltaic effect first time. In addition, this
phenomenon gave the base of using solar energy and Albert Einstein that
published first paper on photoelectric effect.
In addition, we want to dedicate this project to first inventor of solar
cell that was Bell labs who invented first solar cell in 1950.
Also
dedication for parents and teacher for their supports and cooperation
TABLE OF CONTENTS
Abstract
Acknowledgement
Dedication
Table of content list
Table list
Figure list
Conclusion
Recommendation
References
Chapter 1 Introduction
1.1 Project Idea
1.2 Project Block Diagram
1.2.1 Solar Panel
1.2.2 Voltage Regulator circuit
1.2.3 Charge Controller
1.2.4 Voltage Doubler
1.2.5 Battery
Chapter 2 Literature Review
2.1
Solar Energy need
2.2 Need for a sustainable energy sources
2.2.1 Limited fossil fuels
2.2.2 Environmental Impact of fossil
fuels
2.3 Solar Energy-A Sustainable Clean
Energy resource
2.4 Solar Energy-Advantages
2.5 Applications of Solar Energy
Chapter 3 Solar Panel
3.1
Parts of Solar Panel
3.2 Types of Solar Panel
3.2.1 Mono Crystalline
3.2.2 Poly Crystalline
3.2.3 Hybrid Crystalline
3.3 Flexible Thin Film Panel
3.4 Efficiency of Solar Panel
3.5 Availability of Solar Panel
3.6 Testing of Solar Panel
Chapter 4
Voltage Regulator
4.1
Dc-Dc Convertor
4.1.1 Buck Regulator
4.1.2 Boost Regulator
4.1.3 Buck Boost
Regulator
4.1.4
Cuk Regulator
4.2 Voltage Regulator Circuit
4.2.1 Operation of LM317
4.3 Designing of Voltage Regulator Circuit
Chapter 5 CHARGE CONTROLLER
5.1 Solar Charge Controller
5.2 Microcontroller
5.2.1 Functions of
Microcontroller
5.2.2 Analog to
Digital Conversion(ADC)
5.2.3 LM317 Voltage
Regulator
5.2.4
LM7805 Voltage Regulator
5.3 Battery Discharging
5.3.1 Relay
5.3.2 Transistor
5.3.3 Battery
5.3.4 Types of Battery
5.4 Working of Charge Controller
TABLE LIST
|
Table
3-1 Voltage and current measurement
for Solar Panel
|
|
LIST OF FIGURES
|
Figures
Figure: 1-1 Block Diagram of Solar Laptop Charger
Figure: 2-1 Energy Consumption Diagram
Figure: 2-2 Distribution of Solar Energy Radiation Map
Figure: 3-1 Solar Panel
Figure: 3-2 Mono Crystalline Panel
Figure: 3-3 Poly Crystalline Panel
Figure: 3-4 Hybrid Solar Panel
Figure: 3-5 Folded Sheet Panels
Figure: 4-1 Buck Regulator
Figure: 4-2 Boost Regulator
Figure: 4-3 Buck Boost Regulator
Figure: 4-4 Cuk Convertor
Figure: 4-5 LM317 Voltage Regulator Circuit
Figure: 4-6 Current Regulator Circuit
Figure: 4-7 Voltage Regulator Circuit
Figure: 5-1 Pic 16F877A
Figure: 5-2 Voltage Sensing Circuit Diagram
Figure: 5-3 LM317 Adjustable Regulator Circuit Diagram
Figure: 5-4 LM7805 Voltage Regulator connected to Reset
Pin1
Figure: 5-5 Relay
Figure: 5-6 Transistor 2n2222A
Figure: 5-7 Charge Controller Circuit
|
Page
|
Chapter # 1
Introduction
[1]
World energy usage increases now days, also it is expected that the energy
requirement increase day by day. Main
reasons for increase in usage of energy
Ø The
world population increases
Ø Increasing
economic growth of the country.
These factors enhance the energy needs. Main
energy resources are gas, oil, nuclear energy, solar, wind and hydropower
energy. Mostly energy requirement are full fill by oil, gas and hydropower
energy. Fossil fuel energy resources are very limited also; it causes
environmental pollution so there is need of energy resources that are readily
available and environmental friendly.
Conventional energy recourses are fossil fuels like petrol coal natural
gas and these are obtained by biological process after taken millions of years
heating and formed by passing through biological and chemical reactions. As
millions of years taken by these resources to be formed. Due to the industrial
development energy, demand increases with much faster rate than time taken by
their formation so balance not maintained between our energy requirement and
energy resources production. So it’s more reliable to use the sun energy as it
is readily available. As sun energy is environmental friendly,
economical and available for everyone.
1.1 Project idea:
This
project (solar laptop charging system) based upon solar energy. As it’s the
biggest naturally available resource of energy on earth. Solar panel that is
formed by connecting series of Photovoltaic cells is used for this purpose. Solar cells are used to convert the light
energy from the sun into electrical power using photovoltaic phenomenon. These
cells are connected in series or parallel according to the requirement. For
this system, cells are connected in series. The energy from the panel stores in the batteries that are
rechargeable .as energy may not be using at the time of its production so its
stores in batteries.
1.2 Project block
diagram:
Block
diagram is shown in the figure 1.1 that contains the following elements:
1.
Solar panel.
2.
Voltage regulator circuit.
3.
Charge controller.
4.
Voltage doubler.
5.
Battery.
Here
is the block diagram of our project.
Figure1-1 block diagram of solar
laptop charger
1.2.1 Solar panel:
Photovoltaic cell is
the basic component of the solar panel. These cells are connected in series or
may be connected in parallel to form the solar panels. Size and no. of cell in the panel are all
depends upon the Application, type of solar cell, power rating etc.
Photovoltaic cells are
used to convert the light energy from the sun into dc electrical power by using
the photovoltaic effect i.e. for these packages the electrical characteristics
such as resistance current voltage etc. changes when expose to light. These
cells are connected in series or parallel according or requirement based on
voltage or current application. Solar
panel is rated by its output dc power .for this laptop charging use the solar
Panel having output dc power of 500w and current of 3A.
[16] 1.2.2 Voltage
regulator:
The
output voltage from the solar panel is not constant, so there is need to
stabilize output voltage by using voltage regulation circuitry. Voltage
regulator circuits set voltage level according to the requirement also; we
obtain the pure dc voltage that carries no ripples. Voltage regulations can be
done by many methods either by using the dc-dc convertor or by using the
voltage regulator ICs. For laptop charging voltage regulator IC Lm317 is used
here, as it is more efficient and more reliable then then other dc-dc convertor
that are made by using the discrete component contains inductor, capacitors,
resistor etc. Also they occupy more area
and more cost as compare to the voltage regulator IC.
[10] 1.2.3 Charge
controller:
Charge
controller circuitry is used for keep on check on the battery charging and
discharging. It increases the lifetime of the battery. Microcontroller
(16f877A) is used as controller. It is
programmed in such a way that if the battery is fully charged then it
disconnects the battery from the panel; also, it prevents the complete
discharging of battery as it may cause the severe danger. Following are the
function of charge controller circuit.
1.
Charge controller keeps on check the voltage by the panel that charges the
battery.
2.
It checks the battery voltage. It decides whether battery needed charging or
not.
3.
It decides when the load is connected and disconnected. As the battery voltage
reduces to a certain minimum level then it disconnects the load.
1.2.4 Voltage doubler:
Voltage
doubler circuit used for increasing the current and voltage that got from the
voltage regulator. As the panel and
system operate, whole system contains many circuits that need power for their
operation. No ac power is used so the currents and voltage from the panel is
divided for operating the many circuits.
Sufficient current is needed for battery charging so voltage doubler
circuit is used to amplify the current and voltage. These circuits provide the
sufficient current for charging of battery. Also for very low value of the
voltage when the weather is cloudy, then this circuit provides the sufficient
voltage and current. At very low voltage it can give enough current and voltage
to charge laptop batteries.
[7] 1.2.5 Battery:
Energy
storing batteries are needed to stores the energy from panel as the usage of
energy may not require at the time of its production so the electrical charge
storing batteries are require to store the energy .so its charged the load when it is needed
also
if we directly charged load by panel then by electrical surges load may damage
so to ovoid this batteries are used that suppressed the transients by the panel.
Rechargeable
batteries are energy storing batteries called secondary batteries. It is the
type of the electrical batteries and is formed by connecting no. of
electrochemical cells. These batteries are available in different sizes and
this size depends upon need for the application.
There
are many types of rechargeable batteries such as nickel cadmium (NiCd) lithium
ion batteries (Li-ion) and lead acid etc.
Rechargeable
batteries having initial cost but as these batteries are rechargeable and used
many time. Therefore, this is the main advantage of rechargeable batteries.
…………………………….
CHAPTER # 2
LITERATURE
REVIEW
[5] 2.1 Solar Energy Need:
As the
world’s population increasing day by day. Also world industrial development
enhances rapidly, so more energy resources are required to fulfill world’s
energy requirements. There are many natural resources of energy like coal, gas,
hydro power these are called primary resources. Primary resources of energy are
not readily available also they take lot of years for their production. So
there is need of energy resource that is readily available also it can be
easily produced. So solar energy is the best source of energy that is available
to everyone. So there is need to use solar energy in industries and for other
energy requirement.
2.2 Readily available energy source:
As world energy needs increases day by day
because of increase in energy demands and increase in energy population. As other sources of energy are not present
readily. It takes lot of time for their
formation so there is need of energy resource that creates balance between the
energy needs and its formation time. so solar energy is best suited for this
because as sun shines from day to night and provide energy in major portion of
day.so it’s the best source of energy to fulfill world energy needs.
2.2.1
Limited energy resource:
Now days for
our house hold usage primary energy resources are used. That include natural
gas, coal, hydropower etc., these energy resources as these resources are take millions of years for their formation.
As lot of heat and chemical process take place for their formation. So as in
growing need of energy these primary resources are not convenient because it’s
going on decreasing day by day and also take lot of time for their formation so
these resources are limited. Solar energy is the best for our requirement.
As in
advancement in industries and technology number of industries increases day by
day. Due to increase in population world usage of energy increases. Also
imbalanced is created between the energy requirements and formation of energy
resources. As primary sources of energy take lots of time for their formation.
So there is need of energy resource that creates balance between the energy
needs and its formation time. So solar energy is the best source that keeps
balance between energy usage and formation.
Coal: coal is formed by decomposition process.
Hydrocarbons are decomposing by many chemical reactions and also they need
heat. So long time required for their formation. Also they are not readily
available. Also coal present only at limited places on earth.
Oil: it present in liquid form. And crude oil is
the form by combining some hydrocarbons and some inorganic compounds like
oxygen, nitrogen; sulphur etc. crude oil is use as raw material to form other
useful organic matters that can be used as energy resource. But it’s very
difficult process to get other products from crude oil. Also it’s no readily
available.
Natural
gas: natural gas contains methane, propane, butane
also some amount of crude oil. Also natural gas is not readily available. So
it’s not use for long time.
2.2.2
Environmental Impact of Fossil Fuels:
The fossil fuels are mainly carbon based.
Fossil fuels are combusted (burned with oxygen) in order to drive useful
energy, for instance, use of coal in power and use of petrol in automobiles.
The combustion of fossil fuels results in the formation of carbon dioxide (CO2).
After combustion of fuels, CO2 is usually released in the
atmosphere. This gas absorbs the infrared part of radiation from the earth and
re-radiates it back to the earth, creating the effect of a ‘greenhouse’. The
increased temperature of the earth due to the greenhouse effect will result in
erratic weather patterns, folds, droughts and submerging of low-lying areas due
to melting of ice at poles.
[3] 2.3 Solar energy as environmental friendly source:
As solar energy is environmental friendly and
clean energy resource. So it’s better to use more and more sun light than other
energy resources. The Solar Energy”, which has many advantages over the
conventional sources.
The Sun, our nearest and the biggest star, is
the biggest source of energy to us. As radiations of sun presents during major
portion of the day without any cost. As other sources of energy like coal, biomass,
natural gas fossil fuels uses sun energy for their formation.
The energy radiated by the sun is preferable
to other sources of energy because solar radiation is abundant and will last
forever. Solar energy can be produce easily, it may be used for many purposes
and it is a natural resource so it does not have any impact on environment. One
time investment can provide energy for many years at very low cost.
This distribution gives an idea about solar
energy distribution on earth. From this it is clear that solar energy is
available everywhere on earth although not in same proportion. As most of the
developing countries lies in the region where sufficient amount of solar energy
produced. So if these countries properly use sunlight so they can strengthen
their economy.
2.4 Solar Energy- Advantages:
Environmentally
friendly:
Ø Solar panels are environmental friendly also
they can be recycled up to 99%. So solar panels can be used again after passing
them from certain industrial processes. Also lifetime of solar panels are
longer and can be useful for long time.
Ø Large amount of energy can be generated by
using solar radiations. The power obtained from sun intercepted by the earth is
about 1.8X1011 MW, it is sufficient enough to fulfill energy needs
and can run large industries.
Saves
your money:
Ø Solar energy is free and is available to all.
As one time investment can provide energy for 10 to 15 years with almost no
cost.
Ø Because of the improvement in the technology,
the solar equipment’s are getting cheaper.
Independency:
Ø Solar energy is readily available and also it
is available to everyone on earth. So its reachable to every one
Ø As solar energy is available to everyone so
each individual can use solar energy independently. And every can make use of
sun energy for his own purposes.
Maintenance:
·
As solar
panels are designed that can bear the environmental effects so maintenance is not
required for them.
·
As solar
is the natural resource of energy so they are environmental friendly as like
other sources like fuels gas etc.
2.5
Usage of solar energy:
Energy radiated from the sun can be utilized
for many purposes such as
Ø To generate electricity for home and
industries.
Ø For heating water, i.e. sun light directly use
to heat water for house hold usage.
Ø Sun light also use for cooking foods i.e. by
using different mechanisms for this purpose.
So sun provides energy with almost no cost.
Sun light can be used in following different
ways:
1.
Generate electricity with solar panels:
Solar panels are used to convert sun light
into electrical energy. As energy from the sun is in the form of packets of
light so solar panels are used to generate energy from them and photovoltaic
phenomenon is used for this purpose. Solar panels absorb light from the sun and
convert it into electrical energy
2.
Heat up air and water:
For house hold use solar energy is used to heat
water. So by heating water from sun light reduces the electricity bills.
3.
Warm up food:
Solar collector’s boxes are used to heat food
by using sun radiations. So this can save the large amount of primary sources
of energy like coal, gas etc. so it strength the economy. Also provide the
environmental friendly source of energy.
4.
Solar lamp:
Solar lamps use for lighting purposes. They
are portable and easy to use, as they have small size and easily moveable. It
consist of leds that are connected together to produce light. These leds are
electrically connected to each other’s. there is wide variety of design of
solar led lamp are available.
They are used for many purposes such as to
find water level in swimming pools, also used to furnish hotels and picnic
places.
They use solar energy to glow so no electrical
wiring is needed so they can easily be moveable from one place to another. Also
they are environmental friendly as they use
the sun light that have no any harmful effects.
……………………………………………..
Chapter
#3:
Solar
panel
[11]
Solar panel is formed by connecting photovoltaic cell. They got energy from the
sun and generate electrical power. These cells are connected by electrical
connection. When at the output voltage required then these cells are connected
in series. For the current is main output then these cells are connected in
parallel. Mostly Copper, silver wires are used for making electrical
connections. Bypass diode is used at the output its increases the efficiency of
the solar panel.
Figure
3-1 solar panel
[6] 3.1 Parts of solar cell:
As solar panels are formed by repeating unit
cell structure to gets the required length of solar panel so the single unit
cell called solar cell repeating over a structure to form the whole panel.
Following are the part of solar cell that would be discussed below.
Ø Encapsulate: It is made up of glass or other transparent
material such as plastic and mixture of plastic and glass also use for it. The
selection of this material is such that it would not disturb or reduce the
efficiency of cell so mostly transparent material is used for it. For here
glass is used it is use to seal the material from environment effect. That is
to protect the cell from rain, water, and storm. This layer is important
because solar panel are work in open air space so to protect solar cell from
atmospheric effects encapsulate used and it is the top layer of the panel.
Ø Contacts
grids: Contact grid is made up of good conductors.
Mostly material use for contact grid is metals. As metals are very good
conductors as their valance electron is loosely bounded with the atoms so that
support conduction, also metals are readily available so for making contact
grids metallic material is used. Contact grids are using fore collecting the
electrons.
Ø The
anti-reflective coating (AR coating): Function of this
layer i.e. also called A.R. coating to guide the light into solar cell. If this
layer is not used than there is no guided path for the light and most part of
the light would bounce if light guider layer is not use and this layer is
antireflective coating layer. Material refractive index is taking into account
also thickness of layer is important factor for this layer. Both things are
taking into account for this layer. And refractive index changes for different
types of panels.
Ø N
type silicon: when silicon
is doped with pentavalent impurity.so one electron present for conduction.
Ø P type silicon: When silicon (Si) is
doped with trivalent impurity that contains 3 electrons at its outer most electronic
shell as only valance electron is used in bonding. And as trivalent impurity
doped with silicon then as silicon (Si) belongs to group 4 and 3 electrons are
used for bonding and one electron remain unbounded hole is generated when this
electron leave its shell. And likewise hole movement continued. That takes part
in conduction. As holes move in lattice
Ø Back contacts: They cover the entire
solar cell as this layer is metallic layer.
Ø So these are the solar
cell layers explained above and as solar panel are made up by repeating
structure of solar cell. So these layers are present on whole structure.
3.2 Types of solar
panel:
There
are many types of solar panel they are used in different application also
efficiency reduces from one type of the panel to other. There are four main
type of solar panel
Ø Mono
crystalline.
Ø Poly
crystalline.
Ø Hybrid
solar panel.
3.2.1 Mono crystalline:
Cells
in mono crystalline are formed by pure crystalline silicon wafer. They are
efficient when sun lite shine directly on the panel also it’s when sun shines
with intense light
They
are in black color because these cells absorb all colors of light.
Pure
cell are octagonal in shape. When these cells are connected in series the place
remain empty from the corners. As these cells are formed by pure silicon wafer
so cost is higher than poly crystalline panels
So
mono crystalline panel form more power as same size of ploy crystalline panel.
3.2.2 Poly crystalline
panel:
They are made by small silicon offcuts, molded
to form blocks and create cells, so individual crystal are not necessarily
perfectly aligned so loses are present at the joint. As they consist of multi crystalline compounds.
They are comparatively cheaper than the other type but they are less efficient
as compare to other types of solar panel of same size of mono crystalline and
hybrid cell produce more power than poly crystalline cell.
3.2.3 Hybrid
crystalline solar panels:
In
this type of solar cell organic compounds are mix with the silicon that formed
the layer of photoactive material. As they can absorb sunlight and converted
them into electrical energy. Hybrid
silicon cell have advantage over inorganic and organic material. Organic material absorbs light where as in
organic material transport electron in the structure. Whereas s hybrid cell
have both properties as they are combination of organic and inorganic
materials.
Also
they generate more power than crystalline solar cells of same size and area,
but hybrid solar panels are expensive than the other types of solar panels.
[4] 3.3 Flexible thin film panels:
For portable applications flexible thin films
panels are use because they can be folded thus it is easy to carry them. In addition,
these are more resistant to breakage than the mono crystalline and poly
crystalline panels they are lighter than other hard solar panels. But they may
break when bend to sharp angle.
For
laptop charger folded and flexible solar panel are more convenient but it
was not easily available so for testing
of the project uses mono crystalline solar panel otherwise folded panel are
more convenient for this application i.e. for charging laptop batteries.
Most
of flexible sheets of solar panels are forms by polymer solar cell, they are
made by polymer. Polymer are large molecules having repeating structure.
Advantages:
These
types of panel are lighter than other hard materials solar panel. Occupy lesser
area than other crystalline solar cell. Disposable and less expensive than other
solar panels. So these types of panels can be useful for portable applications.
Disadvantage:
They
have less efficiency than other types. So researcher are trying to increase
their efficiency because these are suitable for portable application they are
more also occupy lesser area.. Low cost and can easy to move them.
3.4 Efficiency of solar
panels:
Presently
available Solar panels not absorb
all wave length of light from sun so more part of the sun light wasted. Efficiency of solar panel increases by 2 ways.
Ø If monochromatic light illuminate on panel.
Ø Split the light in different wavelength and
direct them on the panel that tunes to these wavelength values. By these two ways,
efficiency of solar panel raises up to 50%. Commercially now days efficiency of
solar cell is about 25%
Now days 3 dimensional solar cells are designed
to increase the efficiency as they capture and absorb all light from all sides
therefore it boost the efficiency of solar panel to very large extent.
Different
type of solar panel have different efficiency among these type mono crystalline
have highest efficiency of 25 %, poly crystalline have 21 % and. 3 dimensional solar cells are designed
to increase the efficiency as they capture and absorb more light from all sides
therefore it boost the efficiency of solar panel to very large extent.
Researcher
are trying to increase efficiency, also thickness of silicon wafer also reduced
as technology become advanced. This also requires les raw material and les
energy for manufacturing process of solar panels. So as increasing efficiency
of solar panel along with reduction in usage of raw material reduces cost, also
increase in manufacturing of panel that strength the economy.
3.5 Availability of
panel
As
solar panels are manufacture in different sizes also for different values of
current and power ratings. There are different types of solar panels as mention
above; for laptop charging flexible thin sheets panels are more convenient. But
these are not easily available. So for the project used the panel that is
easily available otherwise small size and portable, flexible sheet panel are
more reliable for portable applications.
3.6 Testing
of solar panel
|
Time
|
Load resistance(ohms)
|
voltage
|
Current (A)
|
|
11:00
|
20
|
19.6
|
0.93
|
|
12:00
|
20
|
19.9
|
0.98
|
|
13:00
|
20
|
20.2
|
1.18
|
|
14:00
|
20
|
20.1
|
1.10
|
|
15:00
|
20
|
19.8
|
1.02
|
|
16:00
|
20
|
19.7
|
0.95
|
|
17:00
|
20
|
19.f
|
0.92
|
Table3-1 table for voltage and current
It can be seen
from the table that when the day is clear it gives current and voltage almost
constant during the peak hours of sun shine. It mean that this solar panel is sensitive
to sun light Also during major portion
of day it can be used for charging laptop batteries.
Specifications of solar
panel:
Size: Size of panel is 2x2 feet.
Current and power specifications:
It can draw current of max 3A also power rating is
50 watt.
Also it has connector at the
back. From which achieve final output from the panel san. It is mono
crystalline type solar panel.
Here is the current and voltage value from
panel at different interval of time during day.
………………………………………………….
Chapter # 4
Voltage
Regulator
[16]
Two techniques may be used to get the pure Dc voltage from the solar panel.
These techniques are either by using dc-dc convertor made by discrete components
or by using voltage regulator ICs like lm317.
As voltage, regulators ICs are more efficient and cheaper than
convertors made by discrete components.
Both techniques would be discussed here.
4.1 Dc-Dc convertor:
Dc-to-Dc
convertor is like the transformer as transformer that can step up and step down
Ac voltage. Whereas dc convertors can be used to step up and step down the DC
voltage. We can design them according to our requirement. The regulation of
voltage regulator is achieved by using P.W.M (pulse width modulating) technique
at a fix frequency, and we can use BJT and MOSFET as a switching device.
[15]
Types of dc-dc convertor:
There
are four major types of dc-dc convertor.
1.
Buck regulator
2.
Boost regulator
3.
Book-boost regulator
4.
Cuk convertor.
All
regulators would be discussed below
4.1.1 Buck regulator:
In
a buck regulator, the average output voltage Vo is less than the input voltage
Vin.
This
convertor used the power BJT as switching device. Buck convertor is like step
down dc voltage regulator.
Modes
of Buck regulator:
Mode 1:
This circuit operated in two modes.
Mode
one when transistor Q is switched on at time t=0; during this mode current
rises which passes through inductor L filter capacitor C and resistor.
Mode 2:
this mode began when transisiro1 Q is switched off at time t=t1. Freewheeling
diode conduct during this mode because current continuous flowing through capacitor
inductor and current decreases until transistor switched on again.
Switching
time depends upon the frequency as the time period is reciprocal of frequency.
Average
output voltage is given by
Vo= k×Vs
where k<1
Output
depends upon the frequency and the value of inductor and capacitor. Also the
inductor current is not continuous.
Advantages:
Ø Simple
circuitry required only one transistor for switching.
Ø It
has efficiency about 90%.
Disadvantages:
Ø Input
current discontinuous for these filters are requires at input.
Ø It
can only step down the voltage.
Ø Required
circuit for the protection, because it has possibility of short circuit across
diode path.
4.1.2 Boost regulator:
In boost convertor, output voltage Vo is
greater than the input voltage Vin.
It
used Mosfet for switching. Circuit operation divided into 2 modes
Mode 1:
When transistor is on at time t=0 input current rises and it flow through the
mosfet and inductor.
Mode 2: When transistor is off, at time t=t1 now
current flowing through the capacitor, inductor and load and from diode.
Current decreases until the mosfet turns again. Equation for output voltage is
given by
Vo=Vin/(
1-k) where k<1
Advantages:
Ø It
steps up the voltage without use of transformer. Due to single mosfet, it has
high efficiency.
Ø Input
current is continuous, so no ripples at output.
Disadvantages:
Ø As
by the output equation, the output voltage is too much sensitive to duty cycle
so it’s difficult to keep it stable.
Ø It
only boosts the voltage. Many applications voltage less then input voltage is
also required.
4.1.3 Buck boost
convertor:
It
can convert the output voltage greater then and less than the input voltage. So
it can step up and step down the input voltage. Cascading boost and buck
regulator can obtain the buck and boost convertor.
Operation
of buck boost divided into 2 modes.
Mode 1:
During mode 1 transistor Q1 is turned on so the input current increases and it
passes from inductor and transistor,
Mode 2:
During mode 2 transistor Q1 turned off and now the current flowing through
inductor, capacitor and load. And energy
that was stored in the inductor transfers to the loaded, also current flowing
through inductor falls until transistor Q1 is switched on again.
Average
output voltage equation of buck boost convertor is given by
Vo=(Vin.k)/(1-k)
Buck
or boost operation depend upon duty cycle.
Advantages:
Ø it
can step up and step down input voltage.
Ø It
has high efficiency.
Disadvantages:
Ø Input
current is discontinuous and high peak current passing through transistor.
Ø In
buck boost polarity reversed as polarity of input.
4.1.4
Cuk regulator:
It gives voltage greater than or less than the
input voltage, therefore, it can step up and step down the input voltage level.
Circuit
for Cuk regulator shown below.
Figure 4-4 Circuit for Cuk
regulator
Circuit
operation of cuk regulator divided into two modes.
Mode 1:
when the transistor Q1 is switched on at t=0, current flowing through inductor
L1 and capacitor C1 reversed biased diode Dm. And capacitor gives its storing
energy to circuit formed by C1, C2, and L2.
Mode
2: Mode 2 began when transistor Q1 is turned off at t=t1 now capacitors is
charged by the supply and and energy from the load is transfers to load by
inductor L2.
Average
output voltage equation is given by
Vo=
- (k×Vin) / (1-k)
Negative
sign indicates the negative polarity of output voltage as compared to the input
voltage polarity.
Advantages:
Ø In
cuk regulator, input current is continuous.
Ø The
circuit has low switching losses and high efficiency
Ø It
can step up and step down input voltage.
Ø Convertor
does not allow electromagnetic interference like other convertors.
Disadvantages:
Ø More
components as compared to other regulator as discussed above.
Ø In
cuk convertor capacitors uses as the source of energy transfer, so the ripple
current of C1 also high..
Ø As
these regulator formed by the discrete components also losses increase.
Ø Output
powers of these regulators are smaller. These cannot be used for high power
rating systems.
Ø So
due to these losses use the voltage regulator ICs here such as lm317 as it is
more efficient and more suitable to for laptop charging.
[8] 4.2 Voltage
regulator circuit:
As
linear voltage regulator draw more current, so much amount of power is wasted
when the voltage difference b/w input and output is multiplied by the current. In
addition, this power wasted in the form of heat. Also heat sink required for
this and it occupy more area.When voltage difference is increased the power
wastage going on increases. So alternate is use to voltage regulator ICs, one
of such voltage regulator IC is lm317.
Lm317
IC is used as a voltage regulator. Robert C. Dopkin invented it and Robert j. wilders in1970. It can be
used instead of using the dc - dc convertors made by discrete components. Like
these convertors, it can use to get the pure dc voltage. Following are the
specification of IC.
[9] Specifications:
Lm317
has three pin ic input output and the adjustment. It is like the operational
amplifies. As opam‘s inverting pin is adjustable pin.
Ø Vout
range (1.25V-37V)
Ø Vin-Vout
difference (3-40v)
Ø Maximum
Current (1.5A)
Ø Operation
ambient temperature
4.2.1 Operation of
lm317:
Lm317
can be used in two ways
Ø Voltage
regulator
Ø Current
regulator
a.
Voltage
regulator:
It
can regulate the input voltage circuit
Formula
for output voltage is given by
Vout=
Vin (1+RL/RH)
There
is some error, because some current flow from the adjacent pin.so Vout becomes
Vout=
Vin (1+RL/RH) +IQRL
By
adjusting the value of RL and RH output, voltage can be adjusted.
b.
Current
regulator:
Current
equation of regulator is given by
Iout=Vref/.RL
Error
for quiescent
current is given by
Iout=Vref/.RL +IQ
Lm317
can also be used for current regulation.
4.3 Designing for
voltage regulator circuit:
Lm317 voltage regulator ic use in solar laptop charging
system.
We can
adjust the output voltage by selecting the value of RL And RH, As 16 v is the
required voltage at the output so we have select RL =10K and RH= 2.7K and Vref
or vin =15v we get 20V at output. As formula given by
Vout = Vref (1+RL/RH) with some very small error.
Testing of lm317 regulator performed in lab is given below:
Figure 4-7 voltage regulator
circuit
We get Vout = 15 (1+10/2.7) =16V so we can adjust voltage
for our requirement by selecting the value of RL and RH. As for our requirement
20V is required so we design for it by taking Vout=16v, Vref=15v and select
value for RL =10K so only RH is unknown. That is calculated by formula.
Vout = Vref (1+RL/RH).
16 v is the output voltage.so
output voltage can be adjusted by adjusting the value of resistors.
………………………………………………….
CHAPTER#5
CHARGE CONTROLLER
[10] 5.1 Solar Charge Controller:
When sun shines any time, PV array produces
electricity. All that has needed to get the electrons in those wires moving in
a complete circuit but problem occurs when the battery is fully charged and
more energy is being generated than is being consumed by loads. This may damage
the batteries.
To protect the batteries, controllers come in.
A charge controller is device that is use to limit the rate at which electric
current is added to or drawn from electric batteries. It prevents overcharging
and may prevent against overvoltage, which can reduce battery performance or
lifespan, and may pose a safety risk. It may also prevent completely draining
(“deep discharging”) a battery, or perform controlled discharges, depending on
the battery technology, to protect battery life.
In simple words, solar charge controller is a
device, which controls the battery charging from solar cells and also controls
the battery drain by load. The simple solar charge controller checks the
battery whether it requires charging and if yes it checks the availability of
solar power and starts charging the battery. Whenever controller found that the
battery has reached the full charging voltage levels, it then stops the
charging from solar cell. On the other hand, when it found no solar power
available then it assumes that it is night time and switch on the load. It
keeps on the load until the battery reached to its minimum voltage levels to
prevent the battery dip discharge. Simultaneously Charge Controller also gives
the indications like battery dip discharge, load on, charging on etc.
Controller acts as a manual switch when the
battery bank is full, it automatically cuts off the battery from charging.
However since battery damage can happen quickly, an automated solution is
needed.
Charge controllers can perform the following
functions:
Ø It prevents overcharging.
Ø Protects the battery bank with regime.
Ø Automatic control other equipment in the
system according to the battery bank voltage.
Ø Help to provide the best system performance.
To achieve the best performance the proposed
charge controller is design in the project which consists of microcontroller,
voltage regulator and relay circuit. The microcontroller used is programed
using C# programing language software known as ‘microcode’ to execute the
algorithm. The hex file generated is dumb into the pic controller by means of a
burner.
5.2 MICROCONTROLLER:
Microcontroller is a kind of Miniature
computer containing a processor core, memory, and programmable input/output
peripherals. In the project Pic 16F877A microcontroller is used. It has
following specifications:
Ø It is 40 pins DIP (dual inline package) ic.
Ø It has 256 bytes EEPROM data memory.
Ø It has 368 bytes RAM memory.
Ø Program memory is 8192 words.
Ø It is use 33 pins as IO ports.
Ø One PSP (parallel slave port).
Ø One USART (Universal asynchronous receiver
transmitter).
Ø Two PWM functions.
Ø 8 channels of 10 bit analog to digital (A/D)
converter.
5.2.1 Functions of microcontroller:
The functions of a microcontroller in charge
controller are:
Ø Measures Solar Cell Voltage.
Ø Measures Battery Voltage.
Ø Decides when to start battery charging.
Ø Decides
when to stop battery charging.
Ø Decides
when to switch on the load.
Ø Decides
when to switch off the load.
5.2.2 Analog to Digital Conversion (ADC):
Voltage Sensing:
The microcontroller consists of built in
Analog-to-digital converters. These enable the conversion of our analog inputs
into quantized values. The ADCON registers will need to be configured with
their required binary values to enable ADC to begin.
The Voltage inputs from the panel and the
battery must be stepped down by using voltage division principle. So voltage is
divided by using resistor divider and this node voltage supplied to the ADC pin
(AN1). Similarly, by voltage division principle the battery voltage is divided
and this voltage is supplies to (AN0).
Voltage divider network simulation:
Figure: 5-2 Voltage sensing circuit diagram
1024 quantizes level are formed by ADC of microcontroller.
These values are 0 (for 0V input) and 1023 (for 5V input). In this way, voltage
sensing of the panel and battery is achieved.
[16] 5.2.3 Voltage regulator IC LM317:
LM317 voltage regulator IC is used to maintain voltage level according
to our requirement. The output voltage of solar panel is always fluctuating
which may damage the device so LM317 regulator is used to get the constant
output voltage.
Lm317
has three pin ic input output and the adjustment. It is like the operational
amplifies. As opam‘s inverting pin is adjustable pin.
Ø Vout
range (1.25V-37V)
Ø Vin-Vout
difference (3-40v)
Ø Maximum Current (1.5A)
Ø Operation
ambient temperature
The resistance of the regulator varies in
accordance with the load resulting in a constant output voltage. A linear
regulator employs an active pass device (series or shunt) controlled by a high
gain differential amplifier. It compares the output voltage with a high gain
precise reference voltage and adjusts the pass device to maintain a constant
output voltage. The regulating device is made to act like a variable resistor
continuously adjusting a voltage divider network to maintain a constant output
Using the LM317 regulator the input is regulated. Now why to regulate this
input? The sunlight which is incident on the panel is not always the same I.e.
the intensity of the sunlight is always fluctuating. That’s why it becomes
essential to regulate the input voltage.
The voltage coming from the
regulator is to be limited otherwise the batteries may be overcharged and may
be damaged.
Figure 5-3 LM317 Adjustable Regulator circuit
diagram
5.2.4 LM7805 Voltage Regulator:
LM7805 Regulator is DC regulated IC. The output
voltage is 5v. This IC has three terminal i.e. input, output and ground. It is
very useful IC that can be use in most of electronic circuits. The voltage of
the panel must be stepped down in order to make it compatible with the
microcontroller therefore using the LM7805 IC
The reference voltage circuit is designed
using LM7805 IC is shown in the figure below:
Figure 5-4 LM7805 Voltage regulator connected
to reset pin1
[10] 5.3 Battery Discharging:
5.3.1 Relay:
A relay is an electromagnetic switch. It is
activated when a current is applied to it. Normally a relay is used in a
circuit as a type of switch. There are different types of relays and they
operate at different voltages.
In the project, relay is used when a load is
required to be operated by the battery. It is used to provide the voltage and
current to the battery. One end of the relay is connected to the battery. The
other end is connected to the collector of the transistor BJT (2n2222). The
emitter is connected to ground and the base is controlled by a microcontroller
port (the RB3 pin). When the battery is charging, the voltage of the battery
allows a low current to flow in the relay coil. This low current, induces the
load contact to be switched OFF. When the battery is sufficient enough to run a
load, the base of the BJT is turned on and the current flows from the relay
coil to the load. The relay is now ON.
5.3.2 Transistor:
Transistor is a semi-conductor device having
three layers, three terminals and two junctions.
Figure 5-6 Transistors 2N2222A
A bipolar transistor is a semiconductor device
in which electric current flows due to electrons and holes BOTH,
Simultaneously. Thus both types of charges take part in the conduction of
current through it. Hence it is called bipolar transistor. There are two types
of bipolar transistors, NPN transistor and PNP transistor.
The NPN transistor can be used in two
different modes: forward biased mode and the reverse biased mode. In forward
biased mode, the electric current can easily flow through it. So it acts like a
CLOSED SWITCH. However, in reverse biased mode, the current through it is
practically zero and thus, it acts like an OPEN SWITCH.
In the project 2n2222 n.p.n silicon b.j.t
(Bipolar junction transistor) is used. This little transistor may help in the
project by being used to help drive large loads or amplifying and switching
applications.
5.3.3 Battery:
In stand-alone photovoltaic system, the
electrical energy produced by the PV array cannot always be used when it is
produced because the demand for energy does not always coincide with its
production. Electrical storage batteries are commonly used in PV system.
An electrical battery is one or more
electrochemical cells that convert stored chemical energy into electrical energy.
It consists of number of voltaic cells; each voltaic cell consists of two half
cells connected in series by a conductive electrolyte containing anions and
cations. One half-cell includes electrolyte and the electrode to which anions
(negatively charged ions) migrate, i.e., the anode or negative electrode; the
other half-cell includes electrolyte and the electrode to which cations
(positively charged ions) migrate, i.e., the cathode or positive electrode. In
the redox reaction that powers the battery, cations are reduced (electrons are
added) at the cathode, while anions are oxidized (electrons are removed) at the
anode. The electrodes do not touch each other but are electrically connected by
the electrolyte. Some cells use two half-cells with different electrolytes. A
separator between half-cells allows ions to flow, but prevents mixing of
electrolytes.
As the metal oxidizes, it gives off electrons;
these electrons can also be transferred to another metal in the same
electrolytic solution, resulting in electricity as they flow. The positive and
negative sides of the battery connect to these two metals, but they are not
directly connected to one another. Instead, electrons flow from the negatively
charged side, through a device to positively charged side and hence producing
the current.
The primary functions of a storage battery in
a PV system are:
Ø Energy Storage Capacity and Autonomy: to store
electrical energy when it is produced by the PV array and to supply energy to
electrical loads as needed or on demand.
Ø Voltage and Current Stabilization: to supply
power to electrical loads at stable voltages and currents, by suppressing or
smoothing out transients that may occur in PV system.
Ø Supply Surge Currents: to supply surge or high
peak operating currents to electrical loads or appliances.
[7] 5.3.4 TYPES OF BATTERY:
a. Primary battery(Use and throw type):
Primary
batteries can produce current immediately on assembly. Disposable batteries are
intended to be used once and discarded. These are most commonly used in portable
devices that have low current drain, are used only intermittently, or are used
well away from an alternative power source, such as in alarm and communication
circuits where other electric power is only intermittently available.
Disposable primary cells cannot be reliably recharged, since the chemical
reactions are not easily reversible and active material may not return to their
original forms. Battery manufacturers recommend against attempting recharging
primary cells.
Common
types of disposable batteries include zinc-carbon batteries and alkaline
batteries. In general, these have higher energy densities than rechargeable
batteries.
b. Secondary battery(rechargeable type):
Secondary
batteries have their electrochemical reactions electrically reversible. A
normal battery (primary battery) produces electricity using an electrochemical
reaction. This reaction causes electrons to flow from one electrode to another
through an electrolyte (a liquid or solid chemical substance). The negative (-)
and positive (+) terminals on a battery provide an outlet and inlet for the
electrons to flow. In practice electrical wires are connected to the terminals
and electricity (in the form of electrons) flows through the wires, powering
the device connected to the battery’s terminals. Now reserve everything. In a
rechargeable battery applying an electrical charge to the battery reverses the
chemical reaction that take place. The reversed electron flow restores the
chemical elements involved to their original form and battery is ready to begin
the process again.
In
the project second type of battery i.e. rechargeable battery is being used to
drive the load (laptop).
5.4 Working of the charge controller:
When the program is run on the
microcontroller, the ADC ports of the microcontroller divides the analog inputs
into 1024 quantized levels. These values are 0 (for 0V input) and 1023 (for 5V
input).Controller compares the two voltages; battery and the reference voltage
and performs the functions to run the other devices of the circuit such as
relay, transistor etc. The reference voltage is set to 5 volts using LM7805 IC
at PIN A.1 and battery voltage at PIN A.0. The microcontroller is powered by a
5V supply at pin 11 and 32 ground at pin 12 and 31.
If the battery is in need of charging, the
ports are activated. The battery is only charged if the panel voltage is
greater than 15V. If battery bank is full then controller automatically cuts
off from charging in order to save battery life. If the battery voltage is not
sufficient enough to charge the load then it gets charging from the PV array.
When the solar panel is exposed to sunlight,
the photons are incident on the solar panel. These photons are absorbed by the
solar panel. This absorbed light energy is converted into electrical energy,
which is nothing but the photoelectric effect.
LM317 regulator regulates the fluctuated
voltage of the panel. The regulated output voltage is sensed by the controller
using ADC ports and compares this regulated voltage with the battery voltage.
If battery voltage is less than 12V, then controller activates the port B.3
which is connected to the base of the transistor 2N2222. The transistor 2N2222
is switched ON and allows a low current to flow in the relay coil. This low
current, induces the load contact to be switched OFF and hence battery charging
is achieved.
Simulations of charge controller circuit is
given by:
Figure
5-7 Charge Controller Circuit
Here is the integration of all the circuits used in designing of solar
laptop charging system, containing voltage regulator, relay switching circuit
etc.
………………………………………………….
Conclusion
As the world population increases day by day,
so energy consumption rises also due to the industrial development there are
more and more power needs to run these industries and factories. Conventional
resources for energy are coal, natural gas, etc. they are form in millions of
year so they take long time for their generation so there is need of energy
resource that can balance the energy needs and there time of generation. If we take into account the world energy
resources then sun would be the most readily available source of energy on
earth also it give energy every day from day to night so there is need to use
sun energy to fulfill our needs to overcome the energy crisis. From the recent
data natural energy usage is 20% hydraulic power usage is 25% petroleum and
other hydrocarbons are 35% and only 8% sun energy use to full fill the energy
requirements, so as this resource like natural gas, Coal are not readily
available also long process for their generation so it’s more reliable and
preferable to use sun energy because this energy is readily available. In
addition, it can easily fulfill energy needs of all people. Also solar energy
is one of natural resources of energy so it is environmental friendly and do
not produced any pollution. As solar panels are used to convert sun energy to
electrical efficiency 99% of the panel material is recycle able that after
recycling it can be used repeatedly by passing them from certain process. In
addition, solar panels are design now day that has long lifetime and different
lyres are there to protect them from environmental effects. Life times of solar
panels are also made longer so mostly wander gives warranty of panel for 10 to
15 years. So it’s very long period after the investment. Therefore, researcher
gives more preference to use solar energy than other source of energy.
Solar energy is
readily available and it is the huge source of energy on earth. As the energy
from the sun in one day can fulfil needs of all people on the earth if it would
be properly used.
In addition, energy crisis is main issue that we are
facing now day. So there is need to use the sun energy and the energy from the
other natural resources to overcome all energy crises. So the economy of
country would be strengthening. As many of the industries are closed due to
energy and load shedding issue so by utilizing natural resources this
deficiency can be full filled.
Also as on, the years of modern technology laptop are
readily used. Solar laptop charger can provide be used to charge laptop
batteries without use of ac voltage. Again, in energy crisis issue it is most
reliable to use the natural resources.
This system used battery to store electrical energy. As
energy may not be used as the time it would be generated so as load is not charged directly so first batteries
are charged then it charged the load. As
batteries can resist transients also as energy produced it may not be in use so
storing batteries needed for solar charging system. As major time during day
sun light present but at night and cloudy days it is not present so
rechargeable batteries are used. As transient may damage load so it’s more
convenient to charge laptop batteries similarly in much system battery
keep on connected to panel it reduces the battery life. In the system
microcontroller is used in charge controller circuit. That automatically
disconnects the battery from the panel and increases the battery life.
As 37% of energy used by the electronics
devices, in industries 25% these devices use electrical energy. So the big
portion of energy used by these devices. Therefore, there is, need to use
natural resources to operate electronic devices. So solar energy may be used
after one time investment.as it can give energy almost free of cost for many
years. As laptop, batteries can be charged by solar panels using sun light. As the
panel can convert solar energy into electrical energy and this electrical
energy can operate the circuitry also can be used to charge the laptop
batteries. As laptop charging system contains many circuits that are voltage
regulator, charged controller using microcontroller 16f877A, Voltage doubles
circuit, panel operates these all. Also question arise that when sun light is
not preset at the nighttime then how laptop would be charged when charging of
laptop batteries is required. For this rechargeable batteries are uses. Here
for laptop charging lithium cadmium batteries is used. That is rechargeable
energy from the sun converted into electrical energy by using photovoltaic
effect. As in, certain time it is charged fully,
Therefore, batteries are necessary in solar
systems. For our system battery can charged fully in 2 hours when the weather
is clear.
As electronics,
devices and most of the electronic components and storing devices may damage by
continuously charging. As when the batteries is fully charged there is need to
disconnects the load either manually or automatically. It is most convenient
and efficient to disconnect battery from panel. So as automatically disconnect
of battery increase the battery life. Also, save it from serious danger. For
automatic disconnecting batteries a micro controller 16f877A Is used that is
programed in such a way that it keep on check the battery voltage when voltage
at the terminal is reaches to 20 v then it disconnect the battery as 20V. It ovoid over charging of
battery. Also battery overcharging heat up the battery that may damage for the
internal circuit of charging system.
also deep discharging of battery is also not
required it also damage the battery life so when battery is discharge to
minimum lowest level at that voltage level battery life not be effected, at
this voltage level battery also disconnected from charging of load. So micro
controller have two function that its ovoid over charging and discharging of
battery as both the things are not require and may cause the damage so
programed in such a way that avoid over charging and deep discharging of the
battery. So minimum voltage level defined for the battery also the maximum
level of the battery is defined in the controller that is compared at every
instant. In addition, when this voltage
reaches to the maximum or minimum level then load and panels is disconnecting
using relay.
As it is
solar, based project no power source externally is used so all the circuit are
operated by panels. So as from the panels voltage goes to lm317 is that step up
or down the voltage level and formed the pure dc output so the current is
divided for operating many circuit .as sufficient current is required for
battery charging so to boost the voltage and current voltage doubler circuit is
used here that boost the current and voltage.
So for sufficient current for charging of
batteries this circuitry is used. That can give the sufficient value of voltage
and current even at 6V. Therefore, the purpose of this circuit is to provide
battery charging even with very low value of voltage. That means it can charge
the battery when sun is not shine by its high intensity.
So
here, the whole discussion is above related to the project every element is
discussed above. We are making this project cost effective and trying to make
the project more efficient than the existing ones. As our goal is to make the system
more efficient and cost effective and we have achieved our output to certain
extent.
Recommendation
As the
project is solar based using solar panels to charged laptop batteries. We are
trying to make the system cost effective and efficient. For making project more efficient, we have
used charge controller circuitry, voltage regulator IC lm317 circuits, voltage
doubler circuit. As voltage regulation by lm317 is more efficient than the
other regulator made by discrete components such as buck regulator, boost
regulator, buck and boost regulator cuk regulator, as these regulator are made
by using discrete components such as inductor, capacitor, resistor so they are
not as efficient as voltage regulator ICs, so here we have used voltage
regulator IC that make system more efficient,
Also charge controller circuitry that keep on
check on battery voltages. As the overcharging and deep discharging of battery
is dangerous it also reduces the battery life so charge controller used to
ovoid this. Also by using charged controller battery life become longer.
Voltage
double circuit is use here that gave the sufficient value of voltage and
current that charges laptop batteries even at very low voltages from the
panels. So also we tried to make the system cost effective.
One thing
may be added to modify this project that is to switch the battery charging to
ac voltage when sun light is not present. For this separate system can be
design along with this system that can charged laptop batteries using ac
voltage in cloudy and rainy days.
.
References
[1] Solar photovoltaib– by cheatan singh solanki
[2] Photovoltaic system
engineering [2nd Edition] By Roger A. messenger and jerry venter
[3] Power elecronics
-convertor, Apllications and dsign-[2nd Edition] By Ned Mohan
[4] Batteries and
Charge Control in Stand-Alone Photovoltaic Systems Fundamentals and
Application-Prepared by: James P. Dunlop, P.E.Florida Solar Energy Center1679
clearlacke RoadCocoa, FL 32922-5703
[5] Powe electronics by
Haroon Rasheed
[6] Marzuq Rahman, et
al; “Design of a Charge Controller Circuit for multilevel Solar Panels for
Solar Home System,” 2012.
