solar panel circuit design

VIETNAM NATIONAL UNIVERSITY – HANOI

UNIVERSITY OF ENGINEERING AND TECHNOLOGY

FACULTY OF ELECTRONICS AND TELECOMMUNICATIONS

FINAL REPORT

COURSE: PROJECTS AND SYSTEMS ENGINEERING

Student: Ngo Khac Hoang

Student ID: 10020141

Class: K55Đ

Lecturer: Assoc. Prof. Dr. Nguyen Quoc Tuan

Advisor: Assoc. Prof. Dr. Nguyen Linh Trung

Hanoi, February 2014

THE COMMENT OF ADVISOR

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ESTIMATION:

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MARK:

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REPORTER ADVISOR

SOLAR PANEL CHARGE CONTROLLER

Submitted by Ngo Khac Hoang

Intern from University of Engineering and Technology

Vietnam National University, Hanoi

Supervisor: Dr. Aaron James Danner

In partial fulfillment of the requirements of the Undergraduate Research Attachment Programme

Department of Electrical and Computer Engineering

Faculty of Engineering, National University of Singapore.

Solar Panel Charge Controller 2012

2 |Ngo Khac Hoang

ACKNOWLEDGEMENT

I would like to express my sincere gratitude to my supervisor, Dr. Aaron James

Danner for his guiding, suggestions and encouragements. He spent time to help me to

understand and complete my works step by step throughout my internship period.

I would also like to thank PhD Student Mr. Mridul Sakhuja for his assistance and

helping me to access Digital Electronics Laboratory to do my measurement with solar panels.

He also helped me to complete my final presentation and report. Acknowledgement is also

given to other interns working in Spin and Energy Laboratory, especially Jordan Kodner,

Rumit Kumar Singh and Pooja Sehgal. They supported me in my research work.

I want furthermore to thank all the staff members in Spin and Energy Laboratory and

Digital Electronics Laboratory for give me good conditions to work and take the experiments.

Last but not least, I acknowledge Department of Electrical and Computer Engineering

for providing me the opportunity to do my research under convenient conditions with

enthusiastic persons and get valuable experiences.


3 |Ngo Khac Hoang

ABSTRACT

The aim of this project is to build a charging circuit with 24 small-sized solar panels

which is then controlled by a low power microcontroller. This power charging circuit is used

to supply an indoor solar robot which needs a stable voltage from 1.8 to 3.6 volts.

There are required conditions for the power charging system: (1) supplying a target

voltage and (2) tracking the in maximum power point. That is the reason why the charge

controller is necessary.

This project solves those conditions. The solution for first conditions is making many

different combinations of solar panels in charging circuit. Therefore, we can choose the

suitable combination to get required voltage. The microcontroller changes the combination by

flipping the switches between solar panels. Furthermore, the useful combination must be

symmetrical so that each solar panels and whole system work at maximum power point.

This report show how the power charging circuit can be connected in symmetrical

way. 24 panels were divided into 6 blocks with 4 solar panels inside each. By making

symmetrical combinations of 4 panels in each block and symmetrical combinations between 6

blocks, we can make useful combinations of whole charging circuit.


4 |Ngo Khac Hoang

TABLE OF CONTENTS

ACKNOWLEDGEMENT...................................................................................................................2

ABSTRACT ..........................................................................................................................................3

LIST OF FIGURES..............................................................................................................................6

LIST OF TABLES ...............................................................................................................................6

LIST OF APPENDICES......................................................................................................................6

LIST OF SYMBOLS AND ABBREVIATIONS .............................................................................6

INTRODUCTION ................................................................................................................................7

1. Background ................................................................................................................................7

2. Object ..........................................................................................................................................7

I. SOLAR PANEL AND CHARGE CONTROLLER .................................................................8

1. Solar panel ..................................................................................................................................8

a. Background.............................................................................................................................8

b. Characteristics .......................................................................................................................9

2. Charge controller .................................................................................................................... 11

a. Motivation ............................................................................................................................ 11

b. Solution ................................................................................................................................ 12

II. POWER CHARGING CIRCUIT ......................................................................................... 13

1. Purpose..................................................................................................................................... 13

2. Initial principle ........................................................................................................................ 13

a. Background.......................................................................................................................... 13

b. Dividing................................................................................................................................ 14

c. Switches................................................................................................................................ 14

3. Diagram of one block............................................................................................................. 14

a. List of useful combinations ................................................................................................ 14

b. Diagram ............................................................................................................................... 15

c. Making useful combinations.............................................................................................. 16


5 |Ngo Khac Hoang

4. Diagram of 6 blocks ............................................................................................................... 16

a. List of useful combinations ................................................................................................ 16

b. Diagram ............................................................................................................................... 16

c. Making useful combinations.............................................................................................. 17

5. Combination of whole system .............................................................................................. 17

III. POWER CHARGING CIRCUIT WITH MICROCONTROLLER................................. 19

1. Digital expression ................................................................................................................... 19

2. Application circuit .................................................................................................................. 19

CONCLUSION.................................................................................................................................. 20

FUTURE WORK .............................................................................................................................. 21

REFERENCES .................................................................................................................................. 22

APPENDIX ........................................................................................................................................ 23


6 |Ngo Khac Hoang

LIST OF FIGURES

Figure 1. Solar panel diagram .............................................................................................................9

Figure 2. I-V characteristic of solar panel ...................................................................................... 10

Figure 3. Power – Voltage Characteristic of solar panel .............................................................. 10

Figure 4. Symmetrical Combination Form of n components....................................................... 13

Figure 5. List of useful combinations of 4 panels ......................................................................... 15

Figure 6. Circuit diagram of one block ........................................................................................... 15

Figure 7. List of useful combinations of 6 blocks ......................................................................... 16

Figure 8. Circuit diagram of 6 blocks ............................................................................................. 17

Figure 9. Microcontroller using 3 bits of data ............................................................................... 19

Figure 10. Application circuit .......................................................................................................... 19

Figure 11. Light Meter ...................................................................................................................... 25

Figure 12.Measuring I-V value of one panlel ................................................................................ 25

Figure 13. Outdoor measurement .................................................................................................... 29

Figure 14.Measuring I-V value of 3 solar panels in series........................................................... 33

LIST OF TABLES

Table 1. Switches closed to make useful combination of 4 panels ............................................. 16

Table 2. Switches closed to make useful combination of 6 blocks ............................................. 17

Table 3. Useful combinations of 24 panels made from combinations of 6 blocks and in each

block .................................................................................................................................................... 18

Table 4. Binary bits representing combinations ............................................................................ 19

LIST OF APPENDICES

APPENDIX A. I-V value of Panel 1 under indoor light .............................................................. 23

APPENDIX B. I-V graph of Panel 1 .............................................................................................. 26

APPENDIX C. I-V value of solar panels under outdoor light conditions ................................. 27

APPENDIX D. I-V value of some useful combination of one block under indoor condition 30

APPENDIX E. Mosfet as switch ..................................................................................................... 34

LIST OF SYMBOLS AND ABBREVIATIONS

MPP Maximum Power Point

LED Light Emitting Diode

I-V Current - Voltage


7 |Ngo Khac Hoang

INTRODUCTION

1. Background

Solar panels are electronic devices used to convert solar energy, a clean and abundant

alternative energy, into electrical energy. It is more and more commonly used in both

industrial and daily life. “Solar panels” is also a major topic at the university level.

When using any energy source, an optimization problem of transferring that energy

into electrical energy is observed. For solar cells, current output has a linear relationship with

voltage, so power delivery has a point of maximum efficiency. Solar panels should work at

this point.

To achieve maximum energy, it is necessary to have a charge controller. It also ensures

that the output parameters of the solar system meet the requirements of the device. There are

two ways to do this: voltage control or current control. Voltage control is easier and is

normally chosen.

2. Object

The object of this project is to make the power charging circuit for a lightweight solar

robot with 24 small size solar panels (5x6 centimetres). This robot works under indoor

condition but not in fixed position. Therefore, the intensity of light that the solar panels

receive is not stable.

The charging circuit has two missions: (1) tracking the maximum power point of all

small solar modules as well as whole system and (2) ensuring the output voltage of charging

system meets the required voltage of the robot.


8 |Ngo Khac Hoang

I. SOLAR PANEL AND CHARGE CONTROLLER

1. Solar panel

a. Background

Solar energy is the Earth’s main source of energy, which is not only transmitted to

Earth via light and heat radiation but also the source of many other types of energy like wind

power, water power, and biomass. Humans often make use of these secondary energy

sources. However, directly transforming solar energy into electrical energy is entirely

possible. Solar panels are the tool for that process.

Solar cells or photovoltaic cells (PV) use the photovoltaic effect to converts light into

electric current. Nowadays, the major material used for manufacturing solar cells (and for

semiconductor devices) is crystalline silicon. A solar panel (also solar module, photovoltaic

module or photovoltaic panel) is a packaged, connected assembly of solar cells.

When the panel with a semiconductor p-n junction is exposed to the sunlight, the

photons from the sunlight stimulate more electron – hole pairs. If electron – hole pairs are

close to the p – n junction, the voltage will push the electron exposure of one party (the

semiconductor n) and push hole on the other side (the semiconductor p). Electrons jumping

from valence domain to conduction domain can move freely. The more photons that the solar

panel receives, the more opportunity there is for electrons to jump. If we use an outside wire

to connect n-type semiconductor with p-type semiconductor (via a load such as compacting

LED), there is a current of electrons that follows that direction. Therefore the solar energy of

the light is converted into electrical energy of electrons.

http://en.wikipedia.org/wiki/Solar_cell


9 |Ngo Khac Hoang

Figure 1. Solar panel diagram

<http://www.about-solarenergy.com/wp-content/uploads/2011/10/how-solar-

power-work.png>

b. Characteristics

There are two main points of solar panel’s characteristics.

First, when the intensity of light is stable, the output current and voltage of solar panel

have non-linear relationship.

These below graph show my measurement’s result. I worked with one 5x6 centimeter

size amorphous silicon solar cells under many light conditions.

http://www.about-solarenergy.com/wp-content/uploads/2011/10/how-solar-power-work.png

http://www.about-solarenergy.com/wp-content/uploads/2011/10/how-solar-power-work.png


10 |Ngo Khac Hoang

Figure 2. I-V characteristic of solar panel

Figure 3. Power – Voltage Characteristic of solar panel

0 1 2 3 4 5 6 70

100

200

300

400

500

600

Po

we

r (µ

W)

Voltage (V)

256 lux

315 lux

417 lux

561 lux

631 lux

720 lux


11 |Ngo Khac Hoang

Now we consider each line in Figure 2. At first, when the load resistance value is 0 Ω,

the output voltage is 0 V. When the load resistance value increases, the output voltage

increases as the current falls down. The current will be 0 A when the load is infinite.

Therefore, there is a point in which I*V is maximum i.e. the delivery power is

maximum. I call it Maximum Power Point (MPP). It is clearly visible in the Figure 3. The

solar panel should be controlled to work at this point.

Second, when the intensity of light changes, the electrical parameters of the solar panel

change immediately.

In photovoltaic effect, the opportunity there is for electrons to jump to conduction

domain and move freely depends on how many photons that the solar panel receives.

Therefore, when the light intensity is not stable, the number of photons coming change and

leads the electron current changes.

The brighter light, the higher open circuit voltage, short circuit current and maximum

power. In my measurement, when the light intensity rises from 256 to 720 lux, the m aximum

power point of solar panel increase from 190.464 to 600.237 µW.

One key point is that the maximum power point of solar panel under brighter light is

tracked at higher voltage. Therefore, if we keep the certain voltage, we cannot get the

maximum power under different light conditions.

2. Charge controller

a. Motivation

Because of the nonlinear relationship between current and voltage output of solar

panel, we need to ensure that the panel works at MPP (the load line intersect the I-V

characteristic at MPP).

The electrical parameters, especially voltage of solar panel, are not stable even though

most electric devices need stable supply voltage. For example, when an array of panels is

used to charge some batteries, the excessive voltage can damage the batteries. As the voltage

from the array rises, the charge to the batteries should be regulated to prevent any

overcharging. Therefore, it is necessary to maintain the output voltage of a solar charging

system.

Those two simple reasons show that the charge controller has important role.


12 |Ngo Khac Hoang

b. Solution

In this project, a solar charging system with 24 solar panels is used to supply an indoor

solar robot. This robot requires a stable voltage source (1.8 to 3.6 volts). Two issues have

been outlined above: achieving maximum power point and keeping a stable output voltage.

To solve those problems, a charging circuit is built to combine solar panels in many

different ways. Each way provides different voltage value. Different combinations of panels

are created by flipping switches between them. However, not all of combinations satisfy two

conditions. We need to find the useful ones.

Each switch in the circuit is one Mosfet. They can be switched by controlling the

voltage in the Gate terminals. This function is performed by a low power microcontroller. The

microcontroller senses a light density and target voltage for two purposes: to find the suitable

combination of solar panels and to drive the Mosfets to make that combination.

This project focuses on building power charging circuit.


13 |Ngo Khac Hoang

II. POWER CHARGING CIRCUIT

1. Purpose

The purpose of the charging circuit is to combine the solar panels in suitable way to

get the target voltage output.

There are a lot of combinations for 24 panels. However, not all of them are useful. We

have to find useful combinations.

2. Initial principle

a. Background

There are some required conditions that the circuit has to ensure:

- The output voltage must be close to target voltage

- Each panel and whole system must work at MPP

Suppose that there are n panels. All of them have the same MPP at a given voltage V

and current I (the maximum power in Watts is ). The theoretical maximum power of the

system with n panels is (Watts).

The combinations which satisfy two conditions above must be symmetrical . In general,

the form of a symmetrical combination is:

Figure 4. Symmetrical Combination Form of n components


14 |Ngo Khac Hoang

There are a columns and b rows of solar panels ( ). With each pair of a and b,

there is one combination. In all below part, I name the symmetrical combination having a

columns and b rows by [a, b].

The output current and voltage at maximum power point of whole system are

(amperes) and (volts). The maximum power is:

.

Therefore, the maximum power of this combination is the maximum power possible

when we connect n panels. That is why this is a useful combination.

b. Dividing

To simplify the diagram, I divide 24 panels into 6 blocks. Each block has 4 panels. The

combinations of 24 panels can be made from different combinations in each block and in the

connection between the 6 blocks.

Because 24 panels must be in symmetrical combination, the combination of 4 panels in

each block and combination of 6 blocks must be symmetrical.

c. Switches

Different combinations of charging circuit can be made by flipping the switches put

between solar panels. In the real circuit, we cannot turn the switches on or off by hand. It is

automatically controller by microcontroller. I suggest to use Mosfets as the switches. A

Mosfet can be seen as a switch whose state depends on the voltage of its Gate terminal. The

microcontroller changes that voltage to drive the Mosfet.

3. Diagram of one block

a. List of useful combinations

Because , there are 3 useful combinations for one block

with 4 panels.


15 |Ngo Khac Hoang

Figure 5. List of useful combinations of 4 panels

b. Diagram

Figure 6. Circuit diagram of one block

The circuit has 2 terminals (A, B) and 9 switches.

Solar panel Switch


16 |Ngo Khac Hoang

c. Making useful combinations

To make each useful combination, corresponding switches shown below must be

closed and all other are opened.

No. Combination Switches Closed

1. [1,4] 1,2,7,5,6,9

2. [2,2] 1,2,3,4,6

3. [4,1] 3, 8,4

Table 1. Switches closed to make useful combination of 4 panels

4. Diagram of 6 blocks

a. List of useful combinations

Figure 7. List of useful combinations of 6 blocks

In this case, so there are 4 useful symmetrical

combinations. Suppose that all blocks have the same MPP tracked at given voltage V0 and

current I0.

block


17 |Ngo Khac Hoang

b. Diagram

Figure 8. Circuit diagram of 6 blocks

This circuit has 2 terminals and 15 switches.

c. Making useful combinations

No. Name of combination Switches Closed

1. [1,6] 1,2,5,6,9,10,11,12,13,14

2. [2,3] 1,2,3,4,6,7,8,10

3. [3,2] 1,3,4,7,8,10

4. [6,1] 3,4,7,8,15

Table 2. Switches closed to make useful combination of 6 blocks

5. Combination of whole system


18 |Ngo Khac Hoang

There are 8 useful combinations. Each useful combination of 24 panels can be built by

using useful combinations of 6 blocks, each containing 4 panels that are connected in useful

way.

No. Combination of 24

panels

Combination of 6

blocks

Combination in each

block

1 [1,24] [1,6] [1,4]

2 [2,12] [2,3] [1,4]

3 [3,8] [3,2] [1,4]

4 [4,6] [1,6] [4,1]

5 [6,4] [6,1] [1,4]

6 [8,3] [2,3] [4,1]

7 [12,2] [6,1] [2,2]

8 [24,1] [6,1] [4,1]

[m*x, p*y] [m, p] [x, y]

Table 3. Useful combinations of 24 panels made from combinations of 6 blocks and in

each block

In the order listed, the MPP voltages of the combinations increase while the current

decreases. However, the theoretical maximum power of all combination is 24 times those of

each panel. That is an optimistic number. In total, the charging circuit has 69 Mosfets.


19 |Ngo Khac Hoang

III. POWER CHARGING CIRCUIT WITH MICROCONTROLLER

1. Digital expression

The combinations of the power charging circuit must be converted into digital signal

so that the microcontroller can understand and process them.

There are 8 useful combinations of the 24 panels. It is possible to represent 8 states

with 3 bits of data.

Figure 9. Microcontroller using 3 bits of

data

Bit combinations

000 100

001 101

010 110

011 111

Table 4. Binary bits representing

combinations

2. Application circuit

Figure 10. Application circuit

Microcontroller

Vmeas

SYSTEM

24 solar panels

+ microcontroller


20 |Ngo Khac Hoang

CONCLUSION

The project’s object is to build the power charging circuit for a lightweight indoor

robot using 24 small size solar panels. The current and voltage output of solar panel have

non-linear relationship and these parameters change immediately when the light intensity

changes. Therefore, there are two required conditions: (1) the output voltage must be

maintained to meet required voltage of the robot and (2) each panels and whole system must

work at maximum power point.

To satisfy first conditions, the charging circuit is made so that its combinations can be

changes. At each light condition, the suitable combination supplying the target voltage is

chooses. This function is performed by a low power microcontroller.

There are switches which are Mosfets between solar panels. Each combination of

charging circuit can be made by closing corresponding switches and opening all others. The

states of Mosfet depend on the voltage in its Gate terminal and the microcontroller controls

this voltage to drive Mosfets.

The solution for second condition is connecting solar panels in symmetrical way with a

columns and b rows. The symmetrical combinations are useful because its maximum power

point is the sum of all those of all the panels.

To simplify the diagram, 24 panels are divided into 6 blocks, each block has 4 panels.

There are 3 useful symmetrical combinations of 4 panels, 4 those of 6 blocks and 8 those of

24 panels. Each symmetrical combination of 24 panels is a coordination of one symmetrical

combination in each block and one symmetrical combination between 6 blocks.

In conclusion, the power charging circuit has 24 solar panel connected in

symmetrical combination. There are 8 combinations possible. The microcontroller then uses 3

bits of data to represent and select the combination.


21 |Ngo Khac Hoang

FUTURE WORK

1. Construction of real charging circuit

In total, the power charging circuit includes 24 solar panels, 69 Mosfets as switches

and wires. They are connected follow the diagram shown in the report. Furthermore, the

connection must be scientific so that the charging system is not too big and is easily brought

by the robot. We can optimize the size of charging circuit as 30x40 centimeter.

2. Program a low power microcontroller

The microcontroller is used to control the whole robot and controlling the charge

controller is a part of this. The MSP430 Family and CC2500 Radio should be chosen because

they are really low power with a lot of documentations available and interface as well with

each other.

The microcontroller uses 3 bits of data to select one of the 8 combinations. The bits

are then used to open and close the appropriate MOSFET switches.

3. Conduct test experiments to find the best symmetrical combination

After combine charging circuit and microcontroller programmed, we should conduct

test experiment with the application circuit (page.23).

The power output of charging circuit is charge into a capacitor. The microcontroller

changes the value of 3 bits from 000 to 111 really fast (maybe some nanoseconds). The

voltage charged into the capacitor is measured. After many period of changing (from 000 to

111), the best combination with highest maximum power can be defined.


22 |Ngo Khac Hoang

REFERENCES

[1] Peck Kim Shan, 2011, “Solar Powered Remote Controlled Robot” , Bachelor

Thesis, Department of Electrical and Computer Engineering, National University of

Singapore, Singapore, pp 10-13, 23-24.

[2] Rumit Kumar Singh, 2012, “Antireflective nanostructures for Solar Panel” , Final

Internship Report, Department of Electrical and Computer Engineering, National

University of Singapore, Singapore, pp 29-30.

[3] Wikipedia, “Solar panel”, http://en.wikipedia.org/wiki/Solar_panel, accessed in July

2012.


23 |Ngo Khac Hoang

APPENDIX

APPENDIX A. I-V value of Panel 1 under indoor light

Panel 1 at 256 lux Panel 1 at 315 lux Panel 1 at 467 lux

Voltage

(V)

Current

(µA)

Power

(µW)

0.00002 58.2 0.001164

0.024 58 1.392

0.432 57.7 24.9264

0.66 57.5 37.95

0.975 57.2 55.77

1.237 57 70.509

1.523 56.7 86.3541

1.882 56.3 105.9566

2.133 56 119.448

2.434 55.5 135.087

2.797 55 153.835

3.069 54.5 167.2605

3.153 54 170.262

3.349 53 177.497

3.486 52 181.272

3.532 51 180.132

3.627 50.5 183.1635

3.784 50 189.2

3.858 49 189.042

3.968 48 190.464

4.032 47 189.504

4.118 46 189.428

4.174 45 187.83

4.203 44.7 187.8741

4.205 44.3 186.2815

Voltage

(V)

Current

(µA)

Power

(µW)

0.00002 90 0.0018

0.049 89.7 4.3953

0.153 89.4 13.6782

0.584 89.2 52.0928

0.95 89 84.55

1.206 88.6 106.8516

1.604 88.3 141.6332

2.111 87.5 184.7125

2.506 87 218.022

2.883 86 247.938

3.136 85 266.56

3.41 83 283.03

3.871 79.5 307.7445

4.048 77 311.696

4.249 74 314.426

4.405 72 317.16

4.539 69 313.191

4.66 66 307.56

4.762 64 304.768

4.828 62 299.336

4.907 60 294.42

4.978 58 288.724

5.036 56 282.016

5.083 55 279.565

5.106 54 275.724

5.111 53.5 273.4385

Voltage

(V)

Current

(µA)

Power

(µW)

0.00002 70.2 0.001404

0.525 70 36.75

0.994 69.7 69.2818

1.215 69 83.835

1.536 68.7 105.5232

1.892 68.3 129.2236

2.167 68 147.356

2.48 67.5 167.4

2.704 67 181.168

2.877 66.5 191.3205

3.038 66 200.508

3.287 65 213.655

3.401 64 217.664

3.555 63 223.965

3.754 62 232.748

3.931 60 235.86

4.006 59 236.354

4.101 58 237.858

4.154 57 236.778

4.213 56 235.928

4.282 55 235.51

4.381 53 232.193

4.455 52 231.66

4.546 50 227.3

4.599 49.5 227.6505

4.613 49 226.037


24 |Ngo Khac Hoang

Panel 1 at 561 lux Panel 1 at 631 lux Panel 1 at 720 lux

Voltage

(V)

Current

(µA)

Power

(µW)

0.00003 121.5 0.003645

0.075 121.3 9.0975

0.217 121 26.257

0.908 120.5 109.414

1.224 120 146.88

1.616 119.5 193.112

2.081 119 247.639

2.446 118 288.628

2.889 117 338.013

3.208 115 368.92

3.649 113 412.337

4.045 109 440.905

4.22 106 447.32

4.33 104 450.32

4.577 99 453.123

4.745 94 446.03

4.887 92 449.604

5.042 87 438.654

5.122 84 430.248

5.209 80 416.72

5.307 75 398.025

5.337 73 389.601

5.389 69.5 374.5355

5.432 66 358.512

5.461 64 349.504

5.489 62 340.318

5.514 60 330.84

5.526 58.5 323.271

5.53 58 320.74

Voltage

(V)

Current

(µA)

Power

(µW)

0.00003 142.3 0.004269

0.093 142 13.206

0.476 141.5 67.354

0.827 141 116.607

1.362 140.6 191.4972

1.502 140 210.28

1.892 139.7 264.3124

1.945 139.3 270.9385

2.348 139 326.372

2.556 138 352.728

2.846 137.5 391.325

3.136 136 426.496

3.479 134 466.186

3.816 131 499.896

4.129 127 524.383

4.348 124 539.152

4.709 116 546.244

4.934 110 542.74

5.057 106 536.042

5.137 102 523.974

5.256 97 509.832

5.357 91 487.487

5.404 88 475.552

5.453 84 458.052

5.51 79 435.29

5.554 75 416.55

5.585 71.5 399.3275

5.622 67 376.674

5.655 63 356.265

5.677 60 340.62

5.681 59.5 338.0195

5.689 59 335.651

Voltage

(V)

Current

(µA)

Power

(µW)

0.00003 155.6 0.004668

0.098 155.3 15.2194

0.236 155 36.58

0.966 154 148.764

1.537 153.5 235.9295

1.722 153 263.466

2.299 152 349.448

2.618 151 395.318

2.996 150 449.4

3.373 147 495.831

3.75 144 540

4.139 139 575.321

4.375 135 590.625

4.653 129 600.237

4.907 122 598.654

5.025 118 592.95

5.235 109 570.615

5.346 102 545.292

5.393 99 533.907

5.447 95 517.465

5.489 91 499.499

5.532 87 481.284

5.557 84 466.788

5.609 78 437.502

5.633 75.5 425.2915

5.662 71 402.002

5.686 68 386.648

5.707 65 370.955

5.733 61 349.713

5.738 60 344.28


25 |Ngo Khac Hoang

Figure 11. Light Meter

Figure 12. Measuring I-V value of one panel


26 |Ngo Khac Hoang

APPENDIX B. I-V graph of Panel 1

Panel 1 at 256 lux

Panel 1 at 315 lux

Panel 1 at 467 lux

Panel 1 at 561 lux

Panel 1 at 631 lux

Panel 1 at 720 lux

0 1 2 3 4 50

50

100

150

200

Cu

rre

nt

& P

ow

er

Voltage (V)

Current (µA)

Power (µW)

0 1 2 3 4 50

50

100

150

200

250

Cu

rre

nt

(µA

)

Voltage (V)

Current (µA)

Power (µW)

0 1 2 3 4 5 60

50

100

150

200

250

300

350

Cu

rre

nt

& P

ow

er

Voltage (V)

Current (µA)

Power (µW)

0 1 2 3 4 5 60

100

200

300

400

500

Cu

rre

nt

& P

ow

er

Voltage (V)

Current (µA)

Power (µW)

0 1 2 3 4 5 60

100

200

300

400

500

600

Cu

rre

nt

& P

ow

er

Voltage (V)

Current (µA)

Power (µW)

0 1 2 3 4 5 60

100

200

300

400

500

600

Cu

rre

nt

& P

ow

er

Voltage (V)

Current (µA)

Power (µW)


27 |Ngo Khac Hoang

APPENDIX C. I-V value of solar panels under outdoor light conditions

Panel 4 under cloudy condition Panel 5 under slight sunny condition

Light

intensity (lux)

Voltage

(V)

Current

(mA)

Power

(mW)

2530 0.0027 0.77 0.002079

2500 0.0028 0.76 0.002128

2460 0.374 0.74 0.27676

2430 1.105 0.73 0.80665

2550 2.49 0.72 1.7928

2400 3.68 0.7 2.576

2540 4.41 0.69 3.0429

2400 5.03 0.63 3.1689

2520 5.51 0.66 3.6366

2430 5.78 0.49 2.8322

2460 5.99 0.44 2.6356

2520 6 0.44 2.64

2500 6.08 0.36 2.1888

2540 6.14 0.32 1.9648

2570 6.18 0.3 1.854

2500 6.2 0.39 2.418

2460 6.24 0.39 2.4336

2440 6.28 0.35 2.198

2430 6.32 0.31 1.9592

2430 6.39 0.2 1.278

2450 6.41 0.19 1.2179

2460 6.42 0.18 1.1556

2470 6.44 0.16 1.0304

2470 6.45 0.15 0.9675

2430 6.45 0.14 0.903

2480 6.47 0.14 0.9058

2480 6.47 0.13 0.8411

2520 6.48 0.13 0.8424

2520 6.48 0.11 0.7128

2550 6.49 0.1 0.649

Light intensity

(lux)

Voltage

(V)

Current

(mA)

Power

(mW)

4370 0.0049 1.425 0.006983

4440 0.0051 1.42 0.007242

4470 0.123 1.42 0.17466

4520 1.383 1.41 1.95003

4560 2.25 1.41 3.1725

4440 5.33 1.22 6.5026

4360 5.65 1.13 6.3845

4410 5.75 1.11 6.3825

4430 6.09 0.93 5.6637

4450 6.19 0.86 5.3234

4560 6.25 0.81 5.0625

4490 6.33 0.7 4.431

4510 6.37 0.64 4.0768

4510 6.39 0.62 3.9618

4540 6.43 0.58 3.7294

4490 6.44 0.52 3.3488

4560 6.48 0.49 3.1752

4480 6.48 0.44 2.8512

4580 6.51 0.44 2.8644

4450 6.52 0.36 2.3472

4430 6.53 0.33 2.1549

4390 6.55 0.29 1.8995

4370 6.56 0.28 1.8368

4560 6.57 0.26 1.7082

4370 6.72 0.11 0.7392

4410 6.72 0.105 0.7056

4440 6.73 0.103 0.69319

4460 6.73 0.09 0.6057

4510 6.74 0.09 0.6066

4490 6.74 0.09 0.6066


28 |Ngo Khac Hoang

Panel 5 under sunny conditions Panel 5 under sunniest condition

Light

intensity

(lux)

Voltage

(V)

Current

(mA)

Power

(mW)

55600 0.0879 15.51 1.363329

55600 1.599 14.69 23.48931

55800 6.4 10.37 66.368

55800 6.45 10.49 67.6605

56200 6.51 9.95 64.7745

55700 6.75 7.88 53.19

55400 6.76 7.41 50.0916

56000 6.86 5.57 38.2102

56000 6.87 6.5 44.655

56000 6.93 5.77 39.9861

55600 6.97 5.36 37.3592

55600 6.97 5.36 37.3592

56300 6.98 5.34 37.2732

55900 6.98 5.3 36.994

55800 6.98 5.28 36.8544

55400 6.98 5.11 35.6678

55600 7.02 4.54 31.8708

55800 7.15 1.75 12.5125

56000 7.15 1.74 12.441

55600 7.16 0.25 1.79

55800 7.16 0.13 0.9308

56000 7.16 0.1 0.716

55600 7.19 0.18 1.2942

56300 7.19 0.16 1.1504

56000 7.2 1.19 8.568

55900 7.22 0.19 1.3718

55900 7.25 0.19 1.3775

Light

intensity

(lux)

Voltage

(V)

Current

(mA)

Power

(mW)

84600 0.00543 25.09 0.136239

84800 0.0542 25.04 1.357168

84600 0.0555 25.02 1.38861

84800 0.071 24.72 1.75512

84800 1.273 24.73 31.48129

85000 1.308 24.77 32.39916

84600 1.505 23.47 35.32235

85300 1.71 23.25 39.7575

84600 3.65 23.22 84.753

84800 5.14 23.21 119.2994

84600 5.41 20.32 109.9312

84800 5.87 13.94 81.8278

84800 5.87 13.94 81.8278

85100 6.12 13.85 84.762

85100 6.25 7.3 45.625

84600 6.27 6.62 41.5074

84800 6.48 4.92 31.8816

84800 6.61 5.21 34.4381

85300 6.63 5.14 34.0782

85100 6.65 4.44 29.526

85100 6.72 3.35 22.512

84800 7.03 0.17 1.1951

85300 7.05 0.12 0.846

85300 7.16 0.45 3.222

84600 7.21 0.12 0.8652

85200 7.26 0.1 0.726

84600 7.28 0.18 1.3104


29 |Ngo Khac Hoang

Figure 13. Outdoor measurement


30 |Ngo Khac Hoang

APPENDIX D. I-V value of some useful combinations of a block under indoor condition

4 panel in series at 704 lux

Voltage

(V)

Current

(µA)

Power

(µW)

0.02 146 2.92

0.235 145.8 34.263

0.74 145.3 107.522

1.135 145.2 164.802

1.564 145 226.78

2.071 144.8 299.8808

2.733 144.5 394.9185

3.202 144 461.088

3.705 143.8 532.779

4.072 143 582.296

4.75 142.8 678.3

5.09 142.8 726.852

5.51 142.7 786.277

6.28 142 891.76

7.14 141.7 1011.738

7.62 141.3 1076.706

8.17 141 1151.97

8.98 140.8 1264.384

9.33 140.5 1310.865

9.96 140 1394.4

10.43 139.8 1458.114

10.85 139.3 1511.405

11.43 139 1588.77

12.21 138.3 1688.643

12.36 138 1705.68

12.67 137.9 1747.193

13.06 138 1802.28

14.06 137 1926.22

14.43 136 1962.48

15.19 134.5 2043.055

15.85 133 2108.05

16.04 131 2101.24

17.16 129 2213.64

17.74 126.5 2244.11


31 |Ngo Khac Hoang

18.12 125 2265

18.82 120.5 2267.81

19.08 119 2270.52

19.47 117 2277.99

19.98 112 2237.76

20.23 110.3 2231.369

20.25 110 2227.5

20.43 108 2206.44

20.63 106 2186.78

20.87 102 2128.74

21.02 100 2102

21.19 97 2055.43

21.36 94 2007.84

21.54 91 1960.14

21.78 85 1851.3

21.89 82 1794.98

21.99 79 1737.21

4 panels in parallel at 706 lux

Voltage

(V)

Current

(µA)

Power

(µW)

0.07 583 40.81

0.181 582 105.342

0.62 579 358.98

0.931 578 538.118

1.258 576 724.608

1.992 570 1135.44

2.472 566 1399.152

2.674 564 1508.136

3.029 559 1693.211

3.322 553 1837.066

3.966 532 2109.912

4.58 493 2257.94

4.77 475 2265.75

4.82 470 2265.4

5.01 441 2209.41

5.1 423 2157.3

5.26 375 1972.5

5.32 350 1862

5.38 326 1753.88


32 |Ngo Khac Hoang

5.43 301 1634.43

5.45 287 1564.15

5.48 265 1452.2

5.51 250 1377.5

5.54 223 1235.42

5.56 210 1167.6

5.58 197 1099.26

5.6 178 996.8

5.61 170 953.7

5.63 151 850.13

5.66 117 662.22

5.67 104 589.68

5.68 97 550.96

5.69 87 495.03

5.7 76 433.2

5.71 64 365.44

4 panels in 2 columns and 2 rows at 700 lux

Voltage

(V)

Current

(µA)

Power

(µW)

0.03 292 8.76

0.24 291 69.84

0.513 290.8 149.1804

1.178 290 341.62

1.481 289 428.009

1.953 288.3 563.0499

2.107 288 606.816

2.281 287 654.647

2.645 286.5 757.7925

3.196 286 914.056

3.412 285 972.42

3.937 284 1118.108

4.11 283.8 1166.418

4.49 283 1270.67

4.92 282 1387.44

5.19 281 1458.39

5.57 280 1559.6

5.92 278 1645.76

6.29 277 1742.33

6.58 276 1816.08


33 |Ngo Khac Hoang

6.94 274 1901.56

7.39 271 2002.69

7.76 268 2079.68

8 265 2120

8.07 264.5 2134.515

8.28 262 2169.36

8.58 258 2213.64

8.87 254 2252.98

9.01 252 2270.52

9.18 248 2276.64

9.38 244 2288.72

9.52 241 2294.32

9.73 235 2286.55

10 227 2270

10.1 223 2252.3

10.37 211 2188.07

10.5 203 2131.5

10.78 181 1951.18

10.88 172 1871.36

10.94 165 1805.1

11.01 157 1728.57

11.06 149 1647.94

11.13 139 1547.07

11.2 129 1444.8

11.22 125 1402.5

Figure 14. Measuring I-V value of 3 solar panels in series


34 |Ngo Khac Hoang

APPENDIX E. Mosfet as switch

n-type MOSFET as switch

<http://www.physics.udel.edu/~watson/scen103/mos4.html>

p-type MOSFET as switch

<http://www.physics.udel.edu/~watson/scen103/mos5.html>

http://www.physics.udel.edu/~watson/scen103/mos4.html

http://www.physics.udel.edu/~watson/scen103/mos5.html

solar panel circuit design

Documents

power charging circuit

smallsized solar panels

power charging system

indoor solar robot

symmetrical combinations

ngo khac hoang acknowledgement

systems engineering

ngo khac hoang intern