finel-new-solar power phone chrgar

7/28/2019 Finel-new-solar Power Phone Chrgar

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Abstract

This project involves designing a small scale mobile phone charging system which is powered

via a solar panel and that is capable of charging multiple mobile batteries simultaneously. The

project also requires research into the different solar panels available for the small scale system

being designed, as well as into larger solar panels that may be implemented into a buildings

design. Investigations will also have to be made into how the overall system would change if

these larger solar panels were implemented. The small scale test system will also be able to

display information visually to the user of the system regarding the systems overall capacity to

charge at any given time and will also include power management functions.


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Table of Contents

CHAPTER 1 .............................................................................................................................. - 1 -

1INTRODUCTION...................................................................................................................... -1-

1.1 History of the Solar Panel ............................................................................................. - 2 -

1.2 Types of solar cells ........................................................................................................ - 3 -

1.3 Different types of solar panels ....................................................................................... - 4 -

1.3.1 POLYCHRYSTALLINE MODULES.................................................................... - 4 -

1.3.2 MONOCHRYSTALLINE MODULES .................................................................. - 4 -

1.3.3 AMPORPHOUS MODULES ................................................................................. - 5 -

1.4PHOTOVOLTAIC ARRAY...................................................................................................... -5-

1.4.1 PV Cell Chemistries ................................................................................................ - 5 -

1.5 Rational of the topic ...................................................................................................... - 6 -

1.6 Scope of study ................................................................................................................ - 6 -

1.7 Objective of study .......................................................................................................... - 7 -

1.8Problem identification .................................................................................................... - 7 -

CHAPTER 2 .............................................................................................................................. - 8 -

2BACKGROUND THEORIES...................................................................................................... -8-

2.1 current generate in solar panel ..................................................................................... - 8 -

2.2 converters ...................................................................................................................... - 9 -

2.2.1 DCDC Converter .................................................................................................... - 9 -

2.2.2 Switch Mode Converter ........................................................................................ - 10 -

2.2.3 The Buck Converter .............................................................................................. - 10 -

2.3 DCDC Converter Design............................................................................................. - 13 -

2.4 Backup Battery ............................................................................................................ - 13 -

2.5 Battery Types ............................................................................................................... - 14 -

2.5.1 Lead Acid Batteries............................................................................................... - 14 -

2.5.2 Nickel Cadmium (NiCad) ..................................................................................... - 14 -

2.5.3 Nickel Metal Hydride (NilMh) ............................................................................. - 14 -


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2.5.4 Lithium ion (Liion) ............................................................................................... - 14 -

2.6 Determining the capacity of the battery ...................................................................... - 15 -

2.7 Safety Concerns ........................................................................................................... - 15 -

2.8 Mc34063a DCDC converter ........................................................................................ - 16 -

2.9 Charging a Mobile Phone from the Buck Converter Circuit ...................................... - 16 -

CHAPTER 3 ............................................................................................................................ - 18 -

3LITERATURE REVIEW .......................................................................................................... -18-

3.1 Solar Panel .................................................................................................................. - 18 -

3.2 Cell Phone Chargers ................................................................................................... - 20 -

3.3 Backup Batteries .......................................................................................................... - 23 -

3.4 Control IC .................................................................................................................... - 25 -

CHAPTER 4 ............................................................................................................................ - 26 -

4METHODOLOGIES ................................................................................................................ -26-

4.1 Design solution ............................................................................................................ - 26 -

4.2 Main Procidier ............................................................................................................ - 27 -

4.2.1 Solar Panel ............................................................................................................ - 27 -

4.2.2 DC-DC Buck Converter ........................................................................................ - 27 -

4.2.3 5V Regulator ......................................................................................................... - 28 -

CHAPTER 5 ............................................................................................................................ - 29 -

5DESIGN AND IMPLEMENTATION ........................................................................................... -29-

5.1 Solar Panel .................................................................................................................. - 29 -

5.2 Diode D1...................................................................................................................... - 29 -

5.3 Resistor R1 ................................................................................................................... - 30 -

5.4 IC7805 and C1 and C2 capacitors .............................................................................. - 30 -

5.5 Resistor R2 ................................................................................................................... - 30 -

CHAPTER 6 ............................................................................................................................ - 31 -

6.1 Solar Panel use ............................................................................................................ - 31 -

6.2 Testing the Solar Panel................................................................................................ - 31 -

CHAPTER 7 ............................................................................................................................ - 34 -


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7RESULTS .............................................................................................................................. -34-

7.1 Conclusion ................................................................................................................... - 34 -

REFERENCE .......................................................................................................................... - 35 -


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Table of Figures

Figure 1-current generate in solar panel ---------------------------------------------------------------- - 8 -Figure 2-The buck circuit ------------------------------------------------------------------------------- - 10 -

Figure 3-The buck circuit model 1 --------------------------------------------------------------------- - 10 -

Figure 4-The buck circuit model 2 --------------------------------------------------------------------- - 11 -

Figure 5-Li-ion Battery Pack (mega batteries website (2012)) ------------------------------------ - 15 -

Figure 6-LM78M05C IC (my logger website (2012)) ---------------------------------------------- - 17 -

Figure 7-Block diagram --------------------------------------------------------------------------------- - 26 -

Figure 8-Design ------------------------------------------------------------------------------------------- - 26 -

Figure 9-Main Procedure -------------------------------------------------------------------------------- - 27 -

Figure 10-Simulation circuit ---------------------------------------------------------------------------- - 29 -

Figure 11-Solar panel ------------------------------------------------------------------------------------ - 31 -

Figure 12-Testing solar panel --------------------------------------------------------------------------- - 32 -

Figure 13-Charging a phone ---------------------------------------------------------------------------- - 33 -

Table 1-Solar panel output values --------------------------------------------------------------------- - 32 -


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Acknowledgements

I would like to acknowledge and extend my hart felt gratitude to my lectures Mr. Rajeevan and

for his patronage and his vital enlargement on working in this assignment.

To my dearest parents, I should be thankful for their enthusiasm on this regard and their helpful

hand to conclude this successful.

All other who helped even in a word for this work


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Chapter 1

1 Introduction

Solar power is a renewable source of energy, which has become increasingly

popular in modern times. It has obvious advantages over nonrenewable energy sources, such as

coal, oil and nuclear energy. It is nonpolluting, reliable and can produce energy anywhere that

there is sun shining, so its resources are not going to run out anytime soon. It even has

advantages over other renewable energy sources, including wind and water power. Solar power

is generated using solar panels, which do not require any major mechanical parts, such as wind

turbines. These mechanical parts can break down and cause maintenance issues and can also be

quite noisy. Both of these issues are virtually nonexistent with solar panels. Also, the solar cells,

that connected together make up the solar panel, can last up to several decades without

replacement.

However, there is a drawback to solar powerenergy can only be produce when

the sun is shining. To overcome this, usually solar panels are coupled with back up rechargeable

batteries, which can store excess power generated during the day and use it to provide energy to

systems when there is no sun shining. In this way solar power can be used to power houses and

other large scale systems. In these systems DCAC conversion is needed. This is because the

solar panel produces an output that is DC (Direct Current) and the power supply in homes

usually runs off AC (Alternating Current), so conversion is required. For this project, however,

the load to be connected only requires DC input, so DCAC conversion is not needed. Instead,

DCDC conversion would be used to provide the correct power to the system from the power

generated by the solar panel. Using this information, a number of design solutions were

determined and considered.


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1.1 History of the Solar Panel

The first solar cell wasn't built until 1883, when Charles Frits coated the semiconductor selenium

with an extremely thin layer of gold, to form the junctions. But the device was only mildly

efficient, so the modern solar cell was patented a lot later, in 1946, by Russel Ohl (Softpedia,

2013).

The modern age of solar technology arrived in 1954, when Bell Laboratories accidentally found

that silicon doped with certain impurities was very sensitive to light. This resulted in the

production of the first practical solar cells, with a sunlight energy conversion efficiency of

around 6% (Softpedia, 2013).

The first spacecraft to use solar panels was the US satellite Vanguard 1, launched in March 1958,

with solar cells made by Hoffman Electronics. This milestone created interest in producing andlaunching a geostationary communications satellite, in which solar energy would provide a

viable power supply. This was a crucial development which stimulated funding from several

governments into research for improved solar cells (Softpedia, 2013).

The first highly effective GaAs (Gallium arsenide) heterostructure solar cells were created by

Zhores Alferov and his team of USSR researchers, in the 1970. But, the abilities of companies to

manufacture the GaAs solar cell was limited, until the 1980s, by the fact that Metal Organic

Chemical Vapor Deposition (MOCVD or OMCVD) production equipment wasn't developed upto that date (Softpedia, 2013).

In the United States, the first 17% efficient air mass zero (AM0) single-junction GaAs solar cells

were manufactured in production quantities in 1988 by Applied Solar Energy Corporation

(ASEC). As GaAs single-junction cells topped 19% AM0 production efficiency in 1993, ASEC

developed the first dual junction cells for spacecraft used in the United States, with a starting

efficiency of approximately 20%. Eventually GaAs dual junction cells reached production

efficiencies of about 22% (Softpedia, 2013).

Triple Junction solar cells began with AM0 efficiencies of approximately 24% in 2000, 26% in

2002, 28% in 2005, and in 2007 have evolved to a 30% AM0 production efficiency, currently in

qualification (Softpedia, 2013).


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In 2007, two companies from the United States, Emcore Photovoltaics and Spectrolab, have

produced 95% of the world's Triple Junction solar cells, which have a commercial efficiency of

38%. In 2006, Spectrolab's cells achieved 40.7% efficiency in lab testing. And even this has been

topped (Softpedia, 2013).

Scientists at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL)

have set a world record in solar cell efficiency with a photovoltaic device that converts 40.8

percent of the light that hits it into electricity. This is the highest confirmed efficiency of any

photovoltaic device to date (Softpedia, 2013).

1.2 Types of solar cells

Solar cells are classified into three generations, which indicates the order of which each became

prominent. Thus, the first generation cells consist of large-area, high quality and single junction

devices. They involve high energy and labor inputs, which make them rather unpractical today,

because of their rather elevated costs. Single junction silicone devices are approaching the

theoretical limiting efficiency of 33% and achieve cost parity with fossil fuel energy generation

after a payback period of 5-7 years (Softpedia, 2013).

Second generation materials have been developed to address energy requirements and production

costs of solar cells. It is commonly accepted that as manufacturing techniques evolve production

costs will be dominated by constituent materials (Softpedia, 2013).

For the second generation solar cells, alternative techniques have been used, such as vapor

deposition and electroplating, as well as the most successful second generation materials, such as

cadmium telluride (CdTe), copper indium gallium selenide, amorphous silicon and

micromorphous silicon. These materials are applied in a thin film to a supporting substrate such

as glass or ceramics, reducing material mass and therefore costs (Softpedia, 2013).

Third generation technologies aim to enhance poor electrical performance of second generation

thin film technologies, while maintaining very low production costs. These solar cells are aimed

at reaching an even higher efficiency levels than the second generation cells (they are targeting

conversion efficiencies of 30-60%) and there are already a few approaches to achieving these


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high efficiencies, such as: multijunction photovoltaic cell, modifying incident spectrum

(concentration), use of excess thermal generation to enhance voltages or carrier collection

(Softpedia, 2013).

1.3 Different types of solar panels

1.3.1 POLYCHRYSTALLINE MODULES

Polycrystalline (or multicrystalline) modules are composed of a number of different crystals,

fused together to make a single cell (hence the term 'multi'). They have long been the most

popular type of solar module, due to the lower cost in manufacturing the cells. Recently, the cost

of monocrystalline has come down, making them more popular in the residential market

(Enviroshop, 2012).

The construction of these different crystals gives the solar panel a visible crystal grain, or a

'metal flake effect'. They are slightly cheaper to produce than Mono panels, but are also less

efficient (anywhere from 0.5% to 2% less efficient depending on the manufacturer). This is

because the crystal grain boundaries can trap electrons, which results in lower efficiency. The BP

Solar modules that EnviroGroup installs are approximately 13.5% efficient (Enviroshop, 2012).

1.3.2 MONOCHRYSTALLINE MODULES

Mon crystalline, as the name suggests, is constructed using one single crystal, cut from ingots.

This gives the solar panel a uniform appearance across the entire module. These large single

crystals are exceedingly rare, and the process of 'recrystallizing' the cell is more expensive to

produce (Enviroshop, 2012).

This technology is now the most widely available in Australia, with the cost of producing

monocrystalline cells coming down every year. They are still more expensive than

polycrystalline, but can be up to 2% more efficient. EnviroGroup uses SunOwe (14.5%) and

Suntech (16.5%) monocrystalline solar modules for our installations (Enviroshop, 2012).


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1.3.3 AMPORPHOUS MODULES

The manufacture of these panels is highly automated - silicon is sprayed onto the substrate as a

gas (called 'vapour deposition'), which means that the silicon wafer is approx 1 micron thick

(compared to approx 200 microns for mono and poly). This means that the panel uses less energy

to produce therefore will pay itself back from an energy point of view in a shorter time.

However, it also means that the panels are far less efficient than mono or poly (approx 5-6%

efficient) (Enviroshop, 2012).

The electrical connections are etched by a laser. Etching these as long horizontal cells across the

panel makes these less susceptible from being blocked by shade, but it's important to recognise

that there will still be a significant drop-off in performance when the panel is shaded

(Enviroshop, 2012).

Thin-film panels are significantly less efficient than crystalline panels, and a greater number is

required for the same output. On average, a thin film solar array will need 2.5 times more roof

area than mono or poly. This is critical if you intend to increase the size of your system later, as

you may take up your entire north-facing roof for a relatively small system (Enviroshop, 2012).

1.4 Photovoltaic Array

A Photovoltaic (PV) array is the energy source used in this project. PV arrays essentially consist

of a number of internal silicon based photovoltaic cells combined in series and in parallel,

depending on the voltage or current requirements. These cells are used to convert solar energy

into electricity. This occurs when the photovoltaic cells are exposed to solar energy causing the

cells electrons to drift which, in turn, produces an electric current. This current varies with the

size of individual cells and the light intensity (Softpedia, 2013).

1.4.1 PV Cell Chemistries

Photovoltaic cells, or solar cells as they are more commonly referred to, are available

commercially in a number of different semiconductor materials. The most common materials are

monocrystalline silicon, polycrystalline silicon, amorphous silicon and copperindium selenite

(CIS). These technologies consist of pn junction diodes capable of generating electricity from

light sources and usually have efficiencies of 6% 20% in commercial use (Softpedia, 2013).


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The most popular type of thin film photovoltaic technologies is CIS arrays and amorphous

silicon arrays. These thin film panels consist of a layer of silicon sandwiched between a sheet of

glass and a sheet of plastic. A laser scribe is then used to mark out individual cells. They have

very good efficiency on sunny days, better than the crystalline silicon based cells mentioned

below. However they do suffer from a considerable drop in efficiency under cloudy conditions

(Softpedia, 2013).

Mon crystalline and polycrystalline silicon arrays are constructed in much the same way,

however are made up of individual 0.5 V cells connected together to achieve the desired voltage.

They weigh less than the amorphous and CIS arrays, and are about half the size. Although they

do attain as high efficiencies as the amorphous cells, they do perform better under cloudy

conditions, making them very suitable for year round use (Softpedia, 2013).

1.5 Rational of the topic

Modern world power is main problem. Many things are investigating to save power. They are

many problem occurs to charge over phone batteries when they are no electricity power supply

near. Solar module battery charger gives solution for this kind of problem. Through this system

give facility to charge phone batteries by using solar module. Also this system has a backup

battery to give power when the solar power not generate. My main reason for build this system isgive power for charge over phone when there isnt any electrical power supply near.

1.6 Scope of study

The main aim of this Solar module battery charger project is give a facility to charge phone and

camera batteries any ware. Another advantage of use this system is, power saving.


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1.7 Objective of study

Study the types of solar panels and their unique feathers. Study the required voltages for phone and camera batteries. Study the solar power storing methods. Studying the power dividing theories. Design solar module charger Hardware implementation of the system.

1.8Problem identification

Charge the batteries using the solar power. Get the specific voltage through the solar panel. Give the required voltage to the phone battery charger and camera battery charger

same time.

Backup battery voltage supplying time duration


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Chapter 2

2 Back Ground theories

In this chapter give idea about how to calculate and get readings from solar panel and other

circuits. Through this we can practically calculate actual values generate at this circuit.

2.1 current generate in solar panel

Figure 1-current generate in solar panel

This circuit Equivalent circuit of a PV cell what I mention above. Trough we can find current

generated in the solar cell.

(Kharagpur, 2012)


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The current generated in the solar cell by the current source (Iph) is proportional to the amount

of light falling on it. When there is no load connected to the output Vo almost all of the

generated current flows through diode D. The resistors Rs and Rp represent small losses due to

the connections and leakage respectively. There is very little change in Voc for most instances of

load current. However, if a load is connected to the output then the load current draws current

away from the diode D. As the load current increases more and more current is diverted away

from the diode D. So, as the output load varies so too does the output current, while the output

voltage Voc remains largely constant. That is until so much current is being drawn by the load

that diode D becomes insufficiently biased and the voltage across it diminishes with increasing

load (Kharagpur, 2012).

2.2 converters

2.2.1 DCDC Converter

A DCDC converter is a circuit which takes in a DC voltage at the input and converts it to a

different DC voltage level at the output. Linear DCDC converters drop the input voltage to a

lower output voltage only and can be useful in some applications as they are relatively low in

complexity. However, they can prove inefficient as the dropped voltage is dissipated as heat.

This also means that the regulator may require a heat sink, which can sometimes be impractical.Switch mode converters are more complex in their design as they use an inductor and a capacitor

to store energy, as well as having a switch. This increase in complexity is offset by the fact that

switch mode regulators are largle more efficient then their linear counterparts. Also, as there is

less energy being lost in the transfer, thermal management is not as important. Finally, because

of the use of an inductor in the circuit, the energy stored in it can be used to output voltages that

are greater than the input voltage. These basic components can be rearranged to form different

converter, namely the buck converter, the boost converter and the buckboost converter, which

will be discussed in further detail (Kharagpur, 2012)


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2.2.2 Switch Mode Converter

They are called switch mode converters as they use power switching techniques to achieve the

DCDC conversion. The basics of the switch mode operation are explained in this simple

chopper circuit (Kharagpur, 2012).

While the switch is closed, the voltage at the input Vi is applied to the load. While the switch is

open the voltage at the output Vo is zero (Kharagpur, 2012).

2.2.3 The Buck Converter

The buck converter, also known as a stepdown converter, produces a lower voltage on the

output then received on the input. Its circuit consists of an inductor, a capacitor, a diode and a

switch (usually a MOSFET) and can be seen in figure (Kharagpur, 2012).

Figure 2-The buck circuit

The buck circuit has two modes of operation

Mode 1

Figure 3-The buck circuit model 1


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In the first mode the switch is on (closed). This causes all of the input voltage to be applied

across the diode, D, causing it to be reverse biased. During the time the circuit is in this state,

current builds up in the inductor increasing its stored energy. Hence, the output voltage is,

(Kharagpur, 2012)

(Kharagpur, 2012)

Mode 2

Figure 4-The buck circuit model 2

When the switch is off (opened) the current that was stored in the inductor now flows through

the diode, making the diode forward biased. There is no voltage at Vi, so, for the output,

(Kharagpur, 2012)

The increase in current when the switch is turned on must be equal to the decrease in current

when the switch is turned off, as there cannot be a net change in flux in the inductor. Therefore,

(Kharagpur, 2012)


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(Kharagpur, 2012)

So the output voltage, Vo, is determined by the duty cycle of the switch, S. Since the duty cycle

is a ratio and always between 0 and 1, it is clear the voltage on the output will always be less

than Vi (Kharagpur, 2012).

There are, however, some disadvantages of using a switch mode converter. They can be quite

noisy and suffer current ripple and voltage ripple. In the buck converter these are calculated in

the following way,


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(Kharagpur, 2012)

2.3 DCDC Converter Design

A buck converter was chosen as the dcdc converter to be used in this project. It was chosen as

the voltage, under most circumstances, would be greater the voltage required at the load. The

purpose of the converter is to drive the solar panel to operate at its maximum power point bycontrolling the duty cycle of the switch, and to bring the voltage to a low enough level to power

the load (Kharagpur, 2012). In designing the buck converter, the main components which had to

be determined for the circuit are the inductor and the capacitor. A number of parameters have to

be taken into consideration in choosing appropriate values for both circuit components.

2.4 Backup Battery

In systems that utilize solar panels as the source of energy it is recommended to employ some

sort of storage device. A storage device can prove very useful as it can store any unused energy

generated by the solar panel throughout the day and, in turn, this store energy can be used to

power a system when no sunlight is available to the solar panel, thus making the system more

practical. The most realistic choice for this storage device is a backup battery. There are many


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different backup batteries available on the market today, with various different battery

chemistries. A number of battery chemistries that were researched for use in this project are

discussed below, highlighting the advantages and disadvantages of each.

2.5 Battery Types

2.5.1 Lead Acid Batteries

Lead acid batteries are the oldest rechargeable batteries in existance. They are inexpensive,

reliable and widely used today. However, they are quite heavy and for a system like this storage

may be a problem. Also charging times can be quite slow. Overall, lead acid batteries are more

appropriate for larger power applications (batteryuniversity, 2013).

2.5.2 Nickel Cadmium (NiCad)

NickelCadmium batteries have a long shelf life, they can be left to store energy for up to five

years in some cases. They have other advantages aswell, they prefer fast charging and work well

under rigorous condtions, aswell as having quite a high efficiency at 70% 90%. However, they

have a relatively low energy to weight ratio and can suffer from memory effect. Memory effect

is a phenomenom observed in some rechargeable batteries, namely those with nickelcadium

chemistries. It occurs when the rechargeable battery is repeatedly recharged without being fully

discharged. This causes the battery to lose the capacity it originally had, and the performance of

the battery is significantly lowered (batteryuniversity, 2013).

2.5.3 Nickel Metal Hydride (NilMh)

NiMh based battery cells have a larger capacity then the NiCad batteries, so they are lighter,

and are less prone to the memory effect described above. However, they can be more expensive

and have a relatively short storage life with a high self-discharge rate, making them less efficient

(batteryuniversity, 2013).

2.5.4 Lithium ion (Liion)

Liion preforms the most efficiently out of all the battery chemistries discussed, with efficiencies

of up to 99.9%. It also has the best weight to ratio, weighing about half that of a Ni Cad or NI

Mh cell of the same capacity, making the batteries light and easy to to store. The average voltage

of a Liion cell (3.6v3.7v) means one cell would be required for use in charging most mobile


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phones, compared to 3 NiCad or NiMh batteries at 1.2v each. Liion cells also relivatively good

life cycle, as shown in Figure 6.1. Taking all of its advantages into account, it was decided that a

Liion backup battery would be the most suitable for this system (batteryuniversity, 2013).

2.6 Determining the capacity of the battery

It is important that the backup battery has enough capacity to store the excess energy generated

from the solar panel. To determine the capacity of the battery two things had to be taken into

consideration the maximum current output of the solar panel and the maximum number of

hours of sunshine on a given day (batteryuniversity, 2013).

Li-ion Battery Pack

This Liion 18650 3.7V 4400 mAh is rechargeable battery module.

Figure 5-Li-ion Battery Pack (mega batteries website (2012))

2.7 Safety Concerns

Liion batteries are, however, not without their disadvantages. There are some safety issues to be

taken into account when using them. A common protective circuit to help prevent damage to the

battery is built into the battery pack in figure. Overcharging is avoided as the circuit limits the

charge voltage to 4.35V maximum. The circuitry also contains a thermal sensor which

disconnects the charge if the battery reaches a temperature of over 90c. There are preventative

measures in the circuit to avoid over discharge by limiting the discharge voltage to between 2.7V


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and 3V. However, over discharging can still occur and if the voltage drops below 1.5V copper

shunts may form inside the battery causing short circuits and the battery will become unstable

and unsafe to use. Most commercial Liion battery packs have these circuits built in, but caution

is still needed when using them (batteryuniversity, 2013).

2.8 Mc34063a DCDC converter

The charger is connected in to the car cigarette lighter socket, which supplies a DC voltage of 12

V. After disassembling the charger a mc34063a chip was found inside, as shown in above

figure. From researching the chip in the internet it was found that the mc34063a chip is a step

up, stepdown DCDC converter. The chip can be configured either way, but when configured as

a stepdown converter, which it would be in this case, it has an output voltage of 5 V.

This can also be seen in the charging of mobile phones from laptops. The phone is simply

connected to the laptop via a USB (Universal Serial Bus). When devices are connected to the

laptop the USB supplies 5 volts (DC) to the device. No other circuitry is required to charge the

mobile phone. These facts confirmed the findings during research that the charging algorithm for

the mobile phone is located in the phone itself (batteryuniversity, 2013).

2.9 Charging a Mobile Phone from the Buck Converter Circuit

To charge a mobile phone from the DCDC converter built, a regulator would need to be used to

supply a constant voltage to the phone itself. From looking at the Mc34063a DC DC converter

in figure above, it was decided that supplying 5V to the mobile phone would be sufficient. The

output of the built buck converter should be between 5V and 10 V. These voltages would be low

enough to be input to most 5V regulators. It was decided to use a simple 5V linear regulator to

perform the task. The linear regulator selected was the LM78M05C 3terminal positive 5V

voltage regulator, as shown in figure.


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Figure 6-LM78M05C IC (my logger website (2012))

The LM78M05C regulator was ideal as it could handle currents in excess of 500mA, it output a

regulated voltage of 5 volts and it can handle input voltages up to 35 volts, which is very high for

a linear regulator. The regulator also contain internal short-circuit protection which limits the

maximum output current, and safearea protection for the pass transistor which reduces the short

circuit current as the voltage across the pass transistor is increased. The circuit was below

(batteryuniversity, 2013).


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Chapter 3

3 Literature Review

3.1 Solar Panel

Siliconsolar (2012) web site state 12v Solar Battery Charger 5W. AutoSol ThinFilm 12V 5W,designed to maintain the current level of a 12V battery and to protect against the normal

discharge of a battery over time, this battery charger is rated at 5W and it is perfect for

automobiles, RVs, Boats, and more. This model includes battery clamps for easy, fast installation

and removal to change and maintain a different battery when needed. Some of the features of this

product are high durability, safe for kids and adults of all ages, resists extreme weather

conditions, great for automotive, marine, owl, 12V communication equipment, 2 separate wires

leads for easy on/off connection and accessories sold separately. Open Circuit voltage is 25V.

Operating voltage is 22 to 23V. Operating amperage is 420 mA. It weight 5 lbs. Size 12.5 x 18.5

x 1 inch.

Wlanparts (2012) web site state 12V 5W Heavy Duty Solar Panel. Tycon Power Systems

specializes in lower wattage solar panels for remote power applications, 12V high efficiency

panel. The TPS series solar panels are high efficiency designs with excellent low light

performance. The multicrystalline silicon solar cells are laminated with a TPT

(Tedlar/Polyester/Tedlar) and EVA (Ethylene Vinyl Acetate) bi-layer for high reliability and

long life. The cell array is sealed in a heavy duty extruded aluminum frame with a high

transparency low iron tempered glass cover to protect the solar cells from harsh environments;

hail, wind, snow and ice. The solar panels are easy to mount because of the aluminum frame

design. The wired connections are via a weatherproof junction box on the back of the panels.

Suntech (2012) web site state that Suntech solar panel 5 watt, 12 volt, for small solar projects

such as LED lights, tiny motors and small solar battery charger. Used for constructing a solar

battery charger or solar lights. 12v 5w monocrystalline solar panel can charge small batteries for

your mobile phones and other personal devices. This small solar panel is also used for cathode

protection and many other industrial applications.The solar modules are composed of 36

monocrystalline silicon solar cells of similar performance, interconnected in series to obtain the

12 volt output. A heavy-duty anodized aluminium frame provides strength and convenient

mounting access. For each 18 cell series string, one bypass diode is installed to fully utilise


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sunlight and absorb maximum photovoltaic power. Cells are laminated between high

transmissivity, low-iron, 3mm tempered glass and a sheet of tedlar-polyeaster-tedlar (TPT)

material protected by two sheets of ethylene Vinyl acetate (EVA). This prevents moisture

penetrating into the module. Its main specifications are Dimensions 306mm x 216mm x 18mm,

Weight 0.8 Kg, Output voltage 5 W, Pmax 5 W, Vmp 17.4 V, Imp 0.29 A, Voc 21.6 V, Isc 0.32

A and quality assurance number is ISO 9001:2000.

Westfloridacomponents (2012) website state 5W 12V Mono-Crystalline Solar Panel. A heavy

duty anodized frame provides strength and convenient mounting access. Cells are laminated

between high transmissivity, low-iron, and 3mm tempered glass and sheet tedlar-polyester-tedlar

'TPT' material by two sheets of ethylene Vinyl acetate 'EVA'. This protects against moisture

penetrating into the module. Output Power (peak) is 5W. It Max Power Voltage (Vmp) is 17.6V

and Max Power Current (Imp) is 0.278A. Open Circuit Voltage (Voc) 21.6V. It short circuit

current is (ISC) 0.306A.

We can use this solar panel as Security Cameras, Remote Telemetry Units, SCADA, Monitoring,

Fence Charger, Gate Opener, Intelligent Traffic Systems and General Battery Charging

Applications. In automotive, RV or boat applications, 12V solar panels provide enough power to

trickle charge a 12V vehicle or deep cycle battery which can in turn power fans, lights, pumps,

and other small appliances including televisions, VCRs and microwave ovens.

Solarbarn (2012) web site mention Powertech Monocrystalline 5W 12V Solar Panel. This 5

watt/12volt solar panel should generate about 1.5 Amp hours of electricity in one sunny day.

When used to charge a 12 volt battery, it should provide about 1Ah of charge per day, taking into

account system inefficiencies and battery losses. 1Amp hour of battery charge should power a 12

watt -12 volt solar light for one hour or a 1W /12V solar light for twelve hours. It main

specifications are Maximum power 5W, Rated voltage 12V, Open circuit voltage 21V, Short

circuit current: 380mA.

Solarbarn (2012) web site mention Solawatt 5W 12V Solar Panel. It has Rated Power (watts) 5.

Open Circuit Voltage (volts) 20.5. Maximum Power Voltage (volts) 16.5. Short Circuit Current

(amps) 0.33. Maximum Power Current (amps) 0.3. Nominal DC voltage is 12. It weight 1.30.


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We can use that as outdoor lighting and power, electric fence energisers, remote area electricity,

battery maintenance, 12V battery charging, water pumping.

Energymatters (2012) web site state 5W 12V Solar Panel. It has 25 Years Limited Power

Warranty on Solar Panel and 5 Years warranty period, 99.8% of Morningstar's products never

fail. More power in peak hours through Suntech Power Cells. Optimized module performance

with nominal voltage 12 V DC. Bypass diodes to avoid hot-spot effect. Cells are embedded in a

sheet of TPT and EVA 3.2 mm high transmissive low-iron, tempered glass. Unique esthetic

appearance of cells. Attractive, stable,heavy duty anodized aluminum frames with convenient

mounting-access, for high wind-pressure and snow-load. The backside frames are equipped with

drainage holes. So we eliminate the risk that rain or snow water may accumulate in the frame

lumen and freeze or even bend the frame in cold season. Pre-cabled with fast-connecting systems

Customer-desired packing.

3.2 Cell Phone Chargers

Pubarticles (2012) web site mention a solar cell phone charger that uses solar panels-USB Solar

Panel Charger. the DC voltage transformation circuit to the cell phone battery, And can

automatically stop charging the battery after charging to solve when they go out suddenly

without electricity and cell phone battery charger is not around or cannot find a place torecharge, affecting the normal use of mobile phones. Works Solar cells in use since the larger

changes in sunlight, its resistance and relatively high, stable output voltage, output current is also

small, which requires a DC voltage conversion circuit for changing cell phone battery, DC

conversion circuit Figure 1, it is a single tube DC conversion circuit, using single-ended fly back

converter circuit form. When the switch VT1 conduction, the high-frequency transformer T1

primary winding NP of the induced voltage is 2 to 1 negative, 5 positive for the secondary coil

Ns 6 negative, rectifier diode VD1 is off, then high-frequency transformer T1 through the

primary coil Np stored energy; When the cut-off switch VT1, the secondary coil Ns of 5 6 is

negative, high-frequency transformer T1 in the stored energy through VD1 rectifier and

capacitor C3 filter the output to the load. After installation, connect the solar panels, put under

the sun, no-load output voltage of the circuit is approximately 4.2V, the output voltage when the

load is higher than 4.2V may be appropriate to reduce the R5, R5 otherwise increase resistance.


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Circuit current with the strength of the sunlight, normal is about 40mA, and then the charge

current is approximately 85mA.

Buybuyseller (2012) web site state that USB Solar Panel Charger. USB Solar Panel Charger

Multi-function solar emergency charger treasure, which built-in 2600mAH high capacity

rechargeable lithium battery, so that you can charge your cell phone at any place in anytime.

USB Solar Panel Charger solar charging panels can do you a great favor when you work or

travel in the field or when the power outage to make your cell phone keep working at any time in

anywhere, so that you keep in touch with your friends and family members. USB Solar Panel

Charger digital products use the green energy, solar energy which allows you contribute to

environmental protection. This section of panel charger only sale $ 14.43, it is also with the

charging process protection which can effectively extending the battery life on your phone, safe

to use. It has luxurious and elegant style, small size, portable, stylish and elegant. With the

portable USB solar panel charger, you don't need to worry about running out of power when you

are outdoors. The portable solar panel can be charged either by the built-in solar panel and with

the supplied AC adapter and by any USB port. The portable solar panel has 5 different

connectors to suit popular mobile cell phones models and other digital products Ideal for

frequent travelers. The portable solar panel is Compatible with Apple iPhone 4, iPhone 3G/3GS,

iPod Nano/Touch/Classic, Nokia, Moto, BlackBerry, Samsung, Sony Ericsson, PSP, GPS/PDA,

MP3/MP4 and other mobile cell phone models and other products. Battery Capacity is

2600mAh. Input voltage is DC 5V 500mA.Output is DC 5V 800mA.

21st-century-goods (2013) web site mentions a ReVIVE CH-SOLAR-RESTORE Solar USB

Battery Pack. The ReVIVE Solar charger is a great 1500mAh USB solar cell phone charger. You

can also charge it by AC power, by a USB port or by solar power. Use the included suction cups

to attach to your windshield or other windows to maximize positioning to the sun for solar

charging. It also has a builti in LED flashlight. Most smart phone has approximatly 1500 mAh

batteries so this inexpensive device can doulbe your battery capcity. Use your phones USB cord

to attach to this phone for direct charging. It has so many features. Rechargeable battery stores

power for ON-THE-GO charging charge it up with AC, USB or Solar Power convenient

windshield suction mounts included. Gives a FULL-CHARGE to most phones, MP3 players,

GPS, iPod, iPhone, e-Readers, Bluetooth and other USB powered devices. ON-Board battery


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level indicator lets you know how much power is stored. Convenient side-loaded LED flashlight

feature up to 20 hours of light on one charge.

21st-century-goods (2013) web site mentions a ReVIVE SOLAR-RESTORE XL USB Solar

Battery Pack. The Solar Restore XL is a great iPad charger or ereader charger. With an internal

4000 mA lithium-ion rechargealbe battery the Solar Restore is a great solar iPad charger and

Solar Kindle Fire charger.The Solar ReStore XL is a high-efficiency solar panel with 300mA

charging rate in direct sunlight. With your average smartphone needing around 1000mAh to

1500mAh for a full charge, the Solar ReStore XL will be charged up with enough juice after only

3-5 hours of charging in direct sunlight. Leave the Solar ReStore XL in direct sunlight for 13

hours to fully charge its internal 4000mAh battery. The low-self discharge Li-polymer battery

pack stores emergency power for weeks without degradation. High-capacity, rechargeable

4,000mAh battery stores power for ON-THE-GO charging charge it up by the Sun or USB.

High-efficiency solar panel with durable, portable design. Provides USB back-up power for your

smartphones, MP3 players, i Pads, tablets, eReaders like Kindle Fire and more. LED power

indicator shows battery status. Convenient, dual-mode LED flashlight up to 36 hours of light on

one charge.

21st-century-goods (2013) web site mentions a Sunlinq 1 USB Solar Charger 2 Watt 5 Volt

Portable Solar Panel. The SUNLINQ 1 USB Solar charger is a 5 volt 400 mAmp usb solar panel

with 2 watts of charging power designed to charge cell phones, PDA's, MP3/MP4 players, GPS,

digital cameras, batteries and basically any device that is able to connect and charge via USB

(Universal Serial Bus). The SUNLINQ 1 weighs 4 ounces and when folded is compact,

lightweight, and easily stored and transported making it a very portable solar panel. The

SUNLINQ 1, USB Mini charges at a top rate of 400mA and can charge the average cell phone is

2-3 hours or and iPod in 2-4 hours. You can take this will you backpacking or anywhere else and

not have to worry about the extra weight.

Windupradio (2012) web site states that Solar Cell Phone and Battery Charger 6V/12V solar

power source. iSun is a portable, modular solar DC electricity generator with approx. 2 watts

of power output, 50% more than any comparable devices on the global market. It can charge a

MP3 player, or keep the GPS at full power, all thanks to its reliable solar panels. The iSun is

for the business / city type. The iSun comes with 7 plugs that fits in most electronics found on


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the market today: Discman, GPS, MP3 player, Walkman and cell phones. The iSun is for the

outdoors person. The one who needs power when there's none to be found. Now, you can take

longer trips with no fear of your GPS going dead. The iSun project began in 1999 with

research in the market requirements for renewable portable power. Close to 1000 man-hours

were spent researching various portable electronics and consumer's desires in regards to portable

power. With its universal "plug n'play" connection socket, iSun can be attached to power /

recharge / trickle-charge batteries for personal electronics (e.g. cellular phones, PDA, laptops,

walkman, mp3 players), automotive accessories, leisure (e.g. camping) and other consumer

applications with direct connections or using product-specific cables. iSun's replicator docking

mechanism means that power can also be boosted by daisy chaining units together, which results

in more power. The iSun and iSun Sport solar chargers convert sunlight into an electrical

current. How? Light particles (photons) penetrate the solar cell causing electrons to become

agitated. This results in the flow of direct current (DC) electricity. The more sunshine, the more

power the iSun will produce. The iSun unit can be used in all sunny conditions. Naturally,

the brightest conditions will yield better charging output.

3.3 Backup Batteries

tldp (2012) web site state 3 main battery types. One type is Nickel Cadmium (Ni-Cd). Nickel

Cadmium (Ni-Cd) batteries were the standard technology for years, but today they are out of date

and new laptops don't use them anymore. They are heavy and very prone to the "memory effect".

When recharging a NiCd battery that has not been fully discharged, it "remembers" the old

charge and continues there the next time you use it. The memory effect is caused by

crystallization of the battery's substances and can permanently reduce your battery's lifetime,

even make it useless. To avoid it, you should completely discharge the battery and then fully

recharge it again at least once every few weeks. As this battery contains cadmium, a toxic

material, it should always be recycled or disposed of properly. NiCad batteries, and to a some

degree NiMH batteries, suffer from what's called the memory effect. Memory Effect means that

if a battery is repeatedly only partially discharged before recharging, the battery will forget that it

can further discharge. The best way to prevent this situation is to fully charge and discharge your

battery on a regular basis.


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Second battery type is Nickel Metal Hydride (Ni-MH). Nickel Metal Hydride (Ni-MH) batteries

are the cadmium-free replacement for NiCad. They are less affected by the memory effect than

NiCd and thus require less maintenance and conditioning. However, they have problems at very

high or low room temperatures. And even though they use less hazardous materials (i.e., they do

not contain heavy metals), they cannot be fully recycled yet. Another main difference between

NiCad and NiMH is that NiMH battery offers higher energy density than NiCads. In other

words, the capacity of a NiMH is approximately twice the capacity of its NiCad counterpart.

What this means for you is increased run-time from the battery with no additional bulk or

weight.

Last type is Lithium Ion (Li-ion). Lithium Ion (Li-ion) are the new standard for portable power.

Li-ion batteries produce the same energy as NiMH but weighs approximately 20%-35% less.

They do not suffer significantly from the memory effect unlike their NiMH and Ni-Cd

counterparts. Their substances are non-hazardous to the 0. Because lithium ignites very easily,

they require special handling. Unfortunately, few consumer recycling programs have been

established for Li-ion batteries at this point in time.

batteryuniversity (2013) web site mention Charging Lithium-ion. Charging and discharging

batteries is a chemical reaction, but Li-ion is claimed as an exception. Here, battery scientists talk

about energies flowing in and out as part of ion movement between anode and cathode. This

claim has merits, but if the scientists were totally right then the battery would live forever, and

this is wishful thinking. The experts blame capacity fade on ions getting trapped. For simplicity,

we consider aging a corrosion that affects all battery systems.

The Li ion charger is a voltage-limiting device that is similar to the lead acid system. The

difference lies in a higher voltage per cell, tighter voltage tolerance and the absence of trickle or

float charge at full charge. While lead acid offers some flexibility in terms of voltage cut off,

manufacturers of Li

ion cells are very strict on the correct setting because Li-ion cannot acceptovercharge. The so-called miracle charger that promises to prolong battery life and methods that

pump extra capacity into the cell do not exist here. Li-ion is a clean system and only takes

what it can absorb. Anything extra causes stress. Most cells charge to 4.20V/cell with a tolerance

of +/50mV/cell. Higher voltages could increase the capacity, but the resulting cell oxidation

would reduce service life. More important is the safety concern if charging beyond 4.20V/cell.


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The charge rate of a typical consumer Li-ion battery is between 0.5 and 1C in Stage 1, and the

charge time is about three hours. Manufacturers recommend charging the 18650 cell at 0.8C or

less. Charge efficiency is 97 to 99 percent and the cell remains cool during charge. Some Li-ion

packs may experience a temperature rise of about 5C (9F) when reaching full charge. This

could be due to the protection circuit and/or elevated internal resistance. Full charge occurs when

the battery reaches the voltage threshold and the current drops to three percent of the rated

current. A battery is also considered fully charged if the current levels off and cannot go down

further. Elevated self-discharge might be the cause of this condition.

Increasing the charge current does not hasten the full-charge state by much. Although the battery

reaches the voltage peak quicker with a fast charge, the saturation charge will take longer

accordingly. The amount of charge current applied simply alters the time required for each stage;

Stage 1 will be shorter but the saturation Stage 2 will take longer. A high current charge will,

however, quickly fill the battery to about 70 percent. Li-ion does not need to be fully charged, as

is the case with lead acid, nor is it desirable to do so. In fact, it is better not to fully charge,

because high voltages stress the battery. Choosing a lower voltage threshold, or eliminating the

saturation charge altogether, prolongs battery life but this reduces the runtime. Since the

consumer market promotes maximum runtime, these chargers go for maximum capacity rather

than extended service life.

3.4 Control IC

Fairchild Semiconductor (2012) web site state LM78XX/LM78XXA, 3-Terminal 1A Positive

Voltage Regulator. The LM78XX series of three terminal positive regulators are available in the

TO-220 package and with several fixed output voltages, making them useful in a wide range of

applications. Each type employs internal current limiting, thermal shut down and safe operating

area protection, making it essentially indestructible. If adequate heat sinking is provided, they

can deliver over 1A output current. Although designed primarily as fixed voltage regulators,

these devices can be used with external components to obtain adjustable voltages and currents.


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Chapter 4

4 Methodologies

4.1 Design solution

Figure 7-Block diagram

This block diagram gives some basic idea how this circuit works. First get the power through the

solar panel give that voltage to main circuit. Through main circuit it generate, what exact current

or voltage for phone and give that voltage to phone.

Figure 8-Design


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This is the design method that the final system is based on. It is comprised of a solar panel whose

voltage is regulated by a DCDC converter. The power management of the solar panel comes in

the form of maximum power point tracking (MPPT. For this design it entails using an outside

controller to control the circuit.

4.2 Main Procidier

Figure 9-Main Procedure

4.2.1 Solar Panel

First get the solar power through solar panel. A 5 volt 0.5 Watt solar panel is used as the source

of current. The cells in the panel are made up of semiconductor material which transforms light

energy into electrical energy. When the sunlight is maximum, the solar module can generate

around 500 mA. After that that electrical power trnsfer to the buck converter, also known as astepdown converter, produces a lower voltage on the output then received on the input. At the

end that current drive through 5v voltage regulater. To give cansten power supply to the loard.

Externel back up battery cannect to circuit to operate at sun light limited times.

4.2.2 DC-DC Buck Converter

A buck regulator consists of an inductor, a capacitor, a diode, and a transistor that is used as a

switch. The switch is controlled by the PWM, which is generated by a clock on the

microprocessor. When the square pulses of the PWM are high, the transistor is turned on, and

the high voltage from the panels is applied to the inductor, generating a current through it. This

current is delivered to the load and charges the capacitor. Then when the square pulse is low, the

transistor turns off, and the voltage across the inductor is removed. However, current in an

inductor cant change instantaneously so the high voltage reduces to maintain this current.

Eventually the negative voltage at the input of the inductor drops below the threshold of the


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diode, turning it on and discharging the inductor current through the load. During this off time

the capacitor also discharges through the load contributing some to the total load current. By

varying the duty cycle of the clock we can control how much of the ~380 V the load sees, which

will be ~48V if 4 series 12V batteries are to be charged. The capacitor acts as a filter on the 380

volt pulses, minimizing the decay between pulses (inductor current ripple), and generating an

approximate DC output voltage.

4.2.3 5V Regulator

It is an adjustable voltage regulator IC which means it provides Line Regulation (irrespective of

the changes in the input voltage, the output voltage remains constant) and Load Regulation

(irrespective of the changes in load the output voltage is fixed). We can adjust the output voltage

by varying the resistance across the adjust pin. This is needed to have a fixed voltage across the

battery (to limit the current and charge it at constant voltage). Directly connecting the solar panel

to the battery may even explode it due to the varying output from it. The voltage across R1 is

maintained to be 1.25 V using an internal circuit.


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Chapter 5

5 Design and implementation

Figure 10-Simulation circuit

I cant simulate this circuit because I cant find 7805IC.

Regulator 7805 provides regulated 5 volts to charge all types of Mobile phone batteries which

are rated at 3.6 volts. Resistor R2 restricts charging current to a safer level. Point A can also use

to charge Lithium ion and NiMh batteries. High value capacitors C1 and C2 act as current

buffers so that a short duration interruption in current flow from the panel will not affect the

charging process. Red LED indicates the charging process.

5.1 Solar Panel

Solar panel gives voltage and power according to sun light. Power and voltage can be vary

according to getting sunlight.

5.2 Diode D1

Diode D1 allows current into regulator IC to provide regulated voltage to the load.

Load


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5.3 Resistor R1

Resistor R1 restricts current according to the LED.

5.4 IC7805 and C1 and C2 capacitors

The IC7805 regulator was ideal as it could handle currents in excess of 500mA, it output a

regulated voltage of 5 volts and it can handle input voltages up to 35 volts, which is very high for

a linear regulator. The regulator also contain internal short circuit protection which limits the

maximum output current, and safearea protection for the pass transistor which reduces the short-

circuit current as the voltage across the pass transistor is increased.

5.5 Resistor R2

Resistor R2 restricts charging current to a safer level. This resistor cut out more than 400mA

comes through the voltage regulator. From this we can protect phone form getting high current

value.


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Chapter 6

6.1 Solar Panel use

Solar panel given output and input values tested in the lab.

Rated Power (Pr) = 0.6Watts Peak Power (Pmpp) = 0.6 Watts Peak Power Voltage (Vmpp) = 5 Volts Peak Power Current (Impp) = 700 mA Minimum Peak Power (Pmpp min) = 4Watts

Figure 11-Solar panel

6.2 Testing the Solar Panel

Test the charging Time

The energy capacity of the cell phone batteries is 800 mAh. If we test the amperage output of our

charger, we could figure out around how long it would take for the cell phone battery to charge

completely.

It was necessary to understand the amount of power going in to our circuit from the solar cells,

and the amount of power coming out of the circuit and into the cell phone. To find both of these

values, our device was set up as seen in picture.


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Figure 12-Testing solar panel

The solar panel was tested under a different light conditions and calculated output using

multimeter.

Testing solar panel circuit

Table 1-Solar panel output values

Solar Panel


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We attached digital multimeter that measured the current and voltage output in real time from the

leads coming out of the solar cells so that we could calculate the power input when the device

was working. Moreover, we also attached another multimeter that measured the current and

voltage output from our internal circuit, which allowed us to calculate the power output.

Using this data, we could contrast the values and make an estimate of the efficiency of our circuit

and of the time needed to charge the battery. Once the apparatus was set up, we used varying

amounts of light to shine on the solar panel. We then measured the different input and output

power values. We can calculate power using above mention theories.

The experimental data lead us to conclude that the output Amperage of the circuit, if used in sun,

could be about 80 to 100 milliamps. From this data, we estimate that if a cell phone battery were

fully discharged, it would take about 10-12 hours for it to fully charge (the battery has an energy

capacity of 800mAh). Realistically, most cell phone batteries are charged from half charge,

reducing the time needed to charge.

Figure 13-Charging a phone


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Chapter 7

7 Results

7.1 Conclusion

The overall aim of this project was to develop a small scale battery charging system, whichinclude power management functions and a user interface. It required research into various solar

cell technologies and the understanding of the various characteristics of photovoltaic panels to

ensure an optimum solution for the project.

From the start, it was obvious that a DCDC converter would be used as the source and the load

are both DC. After it was found that a suitable DCDC converter for the system could not be

sourced it was decided to design and build a converter specifically for this project. This would

also provide a greater understanding of the DCDC conversion process and the theory behind

choosing the components. A buck converter was designed, as the output voltage to the load

would always be lower than the voltage output by the solar panel. The various component values

were calculated using standard buck converter formulae and the simulated circuit worked as

designed. Parts were sourced for the range of components and the circuit was built.

The charging algorithm for connecting a mobile phone at the load was researched and found that

no algorithm was necessary on the external charger, as the algorithm takes place on the mobile

phone itself. A 5V linear regulator was placed at the output of the buck converter to provide a

constant voltage to a connected mobile phone

Although a backup battery was not used in the demonstration system, various battery cell

chemistries were researched and recommendations made as to how to implement a backup

battery into the design.

There were a number of issues encountered in the design, which have been discussed and along

with possible solutions to these, along with a number of recommendations for larger scale solarpowered systems.


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5W Solar Panel 12V Mono-Crystalline: In Stock Buy Now - West Florida Components . 2013.

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Energy Matters Australia. [ONLINE] Available at: http://www.energymatters.com.au/5w-12v-

solar-panel-amp-regulator-combo-p-680.html. [Accessed 03 February 2013].

ReVIVE CH-SOLAR-RESTORE Solar USB Battery Pack. 2013. ReVIVE CH-SOLAR-

RESTORE Solar USB Battery Pack. [ONLINE] Available at: http://www.21st-century-

goods.com/revive-ch-solar-restore-solar-usb-battery-pack/. [Accessed 06 February 2013].

ReVIVE SOLAR-RESTORE XL USB Solar Battery Pack - 21st-Century-goods.com. 2013.

ReVIVE SOLAR-RESTORE XL USB Solar Battery Pack - 21st-Century-goods.com. [ONLINE]

Available at: http://www.21st-century-goods.com/revive-solar-restore-xl-usb-solar-battery-pack/.


Sunlinq 1 USB Solar Charger 2 Watt 5 Volt Portable Solar Panel by Global Solar Energy. 2013.

Sunlinq 1 USB Solar Charger 2 Watt 5 Volt Portable Solar Panel by Global Solar Energy.

[ONLINE] Available at: http://www.21st-century-goods.com/sunlinq-1-usb-solar-charger-2-

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finel-new-solar power phone chrgar

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