April 11

Major Project Report 2010-2011 MPPT Based Solar Powered Home

1 Electronics Department College of Engineering, Cherthala

ABSTRACT

The development of renewable energy has been an increasingly critical topic in the 21st century

with the growing problem of global warming and other environmental issues. Solar energy is a

renewable source of energy that has the capability of providing the energy for all the activities. The

second best attractive thing is that there is no environment hazard wastes are produced as its output

compared to any other energy sources like coal and petrol.

Our project aims to electrify a small home from the energy generated by solar panels. The solar panel

converts sunlight into electrical energy and this electrical energy is stored in a battery. The energy

stored is used to light up LEDs provided in the rooms where light is needed. Even though the major

intention is lighting, the energy stored can be used to power a radio and a small LED TV. The

designing involves, solar panel, battery charge controller, battery, LED drivers and suitable for low

power applications. In order to provide maximum efficiency we are using “Maximum Power Point

Tracking”(MPPT) algorithm Technique.



ACKNOWLEDGEMENT

We thank Almighty God whole heartedly for all the grace and blessings that he has showered

on us. Without his unseen guidance this project wouldn’t have materialized.

We express our sincere gratitude to our Principal Prof. Dr .T .K. Mani for providing the right

ambiance to carry out our project work.

We would like to extend our hearty gratitude and deep indebtedness to our project guide,

prof. Rajesh M.V, H.O.D in Electronics Engineering, for his valuable guidance and encouragement.

We wish to extend our profound thanks to all our friends and all staff members especially Mr. Suresh

Kumar T.P, Mrs. Lekshmi V.R, Ms. Manju U and Mr. George C Karamel, for their whole hearted

cooperation and valuable assistance provided for the successful completion of the project.



TABLE OF CONTENTS

CHAPTER NO: TITLE PAGE NO:

i. ABSTRACT…………………………………………………………….1

ii. ACKNOWLEDGEMENT……………………………………………..2

iii. TABLE OF CONTENTS………………………………………………3

iv. LIST OF TABLES …….………………………………………………5

vi. LIST OF FIGURES …….……………………………………….. …..6

vii. LIST OF SYMBOL …………………………………………….…..7

1. INTRODUCTION

OBJECTIVE …………………………….………………...….7

PROBLEM SPESIFICATION/NEED OF PROJECT……….8

2. SELECTION OF TECHNOLOGY/SPECIFIC REQUIREMENT ……...9

3. FEASIBILITY STUDY……………………………………………….….12

4. SOFTWARE AND HARDWARE REQUIREMENT

5.1 SOFTWARE……………………………………………….13

5.2 HARDWARE ………………………………………….14

5. DESIGN SPECIFICATIONS

6.1 SOLAR PANEL………………………………………….20

6.2 SEPIC…………………………………………………….20

6.3 CURRENT & VOLTAGE SENSING…………………...21

6.4 GATEDRIVING CIRCUIT……………………………...21

6.5 LOAD SPECIFICATION……………………………….22

6. HARDWARE DESIGN

7.1 BLOCK DIAGRAM…………………………………….…23

7.2 CIRCUIT DIAGRAM…………………………...………...23



7.2.1 BATTERY CHARGING CIRCUIT…………....24

7.2.2 CURRENT SENSING……………… .………...25

7.2.3 MICROCONTROLLER………………………...26

7.2.4 LED DRIVER CIRCUIT……………………….26

7. SOFTWARE DESIGN

8.1 ALGORITHM………………………….…………….27

8.2 FLOWCHART………………………….……………28

8. IMPLEMENTATION OF TECHNOLOGICAL ENVIRONMENT…...30

9. CONCLUSION

10.1TESTING AND RESULT……………………………31

10.2ENHANCEMENT……………………………………31

10.3LIMITATIONS……………………….……………...31

APPENDIX

1. COMPONENT SPECIFICATION WITH COST……………….32

2. PCB LAYOUT ……………………………………………….…34

3. REFERENCE…………………………………………………….35



LIST OF TABLES

TITLE PAGE NO:

1. LCD PIN DISCRIPTION…………………………………………………..20

2. LOAD SPECIFICATION…………………………………………………..22

3. COMPONENT SPECIFICATION…………………………………….,……32



LIST OF FIGURES

TITLE PAGE NO:

1. BASIC BLOCK DIGARAM…………………………………… ………….7

2. MPPT CHARACTERISTICS ………………………………………………10

3. BLOCK DIGARAM OF HARDWARE……………………………………13

4. SOLAR CELL…………………………………………………………….…13

5. VI CHARA OF SOLAR PANEL…………………………………………..14

6. 12V,7Ah BATTERY…………………………………………………………15

7. MICROCONTROLLER……………………………………………………..15

8. SEPIC CONVERTER……………………………..……………...................16

9. SEPIC ON CONDITION CIRCUIT…………………………………………17

10. SEPIC OFF CONDITION CIRCUIT……………………………………….18

11. 5V POWER SUPPLY…………………………………..……………………19

12. LCD 2X16………………………………… ………………,………………..19

13. LCD INTERFACE…………………………………………………………...20

14. DETAILED BLOCK DIAGRAM…………………………..……………….23

15. BATTERY CHARGING CIRCUIT ……………………….………………. 24

16. CURRENT SENSING……………………………………….. …………….25

17. MICROCONTROLLER…………………………………..…………………25

18. LED DRIVER………………………………………………..……………...26

19. BASIC DRIVER IC…………………………………………………………26

20. FLOW CHART………………………………………………………………29

21. PCB LAYOUT OF CHARGING CIRCUIT……………………………….34

22. PCB LAYOUT OF LED DRIVER …………………………………………34

LIST OF SYMBOLS, ABBREVATIONS & NOMENCLATURE

1. MPPT –MAXIMUM POWER POINT TRACKING

2. SEPIC- SINGLE ENDED PRIMARY INDUCTANCE CONVERTER

3. LED-LIGHT EMITTING DIODE

4. LCD-LIQUID CRISTAL DISPLAY

5. PIC-PERIFERAL INTERFACE CONTROLLER

6. PWM-PULSE WIDTH MODULATION



Solar

Array

MPPT

Power

Supply

Vin

Iin Iout

Vout

.

CHAPTER 1:INTRODUCTION

1.1 OBJECTIVE

Our project objective is to electrify a small home using solar energy .The simplified block

diagram is shown in the figure.

FIG 1: BASIC BLOCK OF MPPT BASED SOLAR POWERED HOME

The main part of the project is the solar panel. It converts light energy to electrical energy. It

provides a dc voltage and is used to charge the battery. The output voltage of solar panel depends on

the intensity of light.

The next part of the project is a SEPIC converter. The solar panel provides a higher or a lower

voltage than the voltage required to charge up the battery. When a voltage divider is used most of the

power will be lost. When a dc-dc converter is used, the voltage can be converted to required voltage.

For converting a higher voltage to lower voltage Buck converter and for the conversion of lower to

higher voltage Boost converter is used. Consider the battery charging voltage is 14V, the panel voltage

varies from 8V to 24V with the light intensity. So a buck-boost or SEPIC converter is required. In the

SEPIC converter the input voltage is converted to higher or lower voltage by taking a feedback from

the out -put portion .The feedback is taken by measuring the output voltage.

For the charging purpose an algorithm called MPPT algorithm is implemented. It works by

measuring the various parameters like panel voltage, panel current, battery voltage and battery current.

Consider when the panel supplies 18V and the charging voltage is 14V, when the ordinary charging



process is used, 4V of input will be lost. So by using MPPT algorithm this can be overcome by

tracking the maximum current from the panel and thus improving the efficiency.

On looking the output voltage, the microcontroller provides a PWM and is used for the step

up or step down process. The various loads used in the system are an LED array as light source, a

radio and dc fan .All devices works on dc voltage so we can connect directly to the battery.

1.2 PROBLEM SPECIFICATIONS/NEED OF PROJECT

The problems faced by us are our main feedback. The main problems faced by us are at first

we introduced buck convert but we are not able to provide sufficient voltage at low light intensity.

Another problem faced is on the switching of MOSFET. Switching is first done by PUSH PULL

transistor circuit but its voltage is not able to provide switching. Next problem faced is on the current

sensing circuit at first we used high side current sensor whose voltage across it is difficult to measure.

In this century we need a large amount of energy requirements but we are less in energy

sources and majorly used natural resource of energy like petroleum and coal sources are at the stage of

verdict, at this stage the renewable resources have its importance. By using solar energy we are able to

provide energy till the end of universe. Our project can provide electrical energy to a poor family

which lies on a remote place where the normal supply of electricity is difficult. Since the system has a

large life time it has only the initial buying cost and its maintenance cost is low.



CHAPTER 2: SELECTION OF TECHNOLOGY/SPECIFIC REQUIREMENTS

2.1MPPT:

The project success depends on how efficient is the system. Here in our project when we are

going through the articles and internet we came to know about a technology called MPPT by using it

we can increase the efficiency to a higher level. Maximum Power Point Tracking, frequently referred

to as MPPT, is an electronic system that operates the Photovoltaic (PV) modules in a manner that

allows the modules to produce all the power they are capable of. MPPT is not a mechanical tracking

system that “physically moves” the modules to make them point more directly at the sun. MPPT is a

fully electronic system that varies the electrical operating point of the modules so that the modules are

able to deliver maximum available power. Additional power harvested from the modules is then made

available as increased battery charge current. MPPT can be used in conjunction with a mechanical

tracking system, but the two systems are completely different.

To understand how MPPT works, let’s first consider the operation of a conventional (non-

MPPT) charge controller. When a conventional controller is charging a discharged battery, it simply

connects the modules directly to the battery. This forces the modules to operate at battery voltage,

typically not the ideal operating voltage at which the modules are able to produce their maximum

available power. The PV Module Power/Voltage/Current graph shows the traditional Current/Voltage

curve for a typical 75W module at standard test conditions of 25°C cell temperature and 1000W/m2 of

isolation. This graph also shows PV module power delivered vs. module voltage. For the example

shown, the conventional controller simply connects the module to the battery and therefore forces the

module to operate at 12V. By forcing the 75W module to operate at 12V the conventional controller

artificially limits power production to 53W. Rather than simply connecting the module to the battery,

the patented MPPT system in a Solar Boost charge controller calculates the voltage at which the

module is able to produce maximum power. In this example the maximum power voltage of the

module (VMP) is 17V. The MPPT system then operates the modules at 17V to extract the full 75W,

regardless of present battery voltage. A high efficiency DC-to-DC power converter converts the 17V

module voltage at the controller input to battery voltage at the output. If the whole system wiring and

all was 100% efficient, battery charge current in this example would be VMODULE ¸ VBATTERY x

IMODULE, or 17V ¸ 12V x 4.45A = 6.30A. A charge current increase of 1.85A or 42% would be

achieved by harvesting module power that would have been left behind by a conventional controller

and turning it into useable charge current. But, nothing is 100% efficient and actual charge current



increase will be somewhat lower as some power is lost in wiring, fuses, circuit breakers, and in the

Solar Boost Charge controller.

FIG 2: MPPT CHARACTERISTICS

2.2SEPIC:

We also used single ended primary inductance converter (SEPIC) to convert the varying input

voltage to desired voltage level. SEPIC has advantage compared to other converters like BUCK,

BOOST and BUCK-BOOST converter is that it can convert both low level voltage and high level

voltage to desired voltage level and it has a non inverted output. In SEPIC the output voltage can be

controlled by the PWM switching provide by the controller IC.

2.3BATTERY:

The battery used in our project is Lead acid battery. The commercially available ones contain

either 6 or 12 cells connected together. In each cell, the anode and cathode plates are arranged

alternately and kept separated by separates made of sheets of insulating material. The anode plates

and cathode plates are contacted separately to each other .In a maximum we get 2v from each such

cells. The plates of each electrode are in the form of grids made of lead ore an alloy of lead and

antimony. The cathode plates are coated with red brown lead dioxide while the anode plates are



coated with spongy lead. The plates are kept immersed in dilute sulfuric acid (specific gravity 1.15

at 25 degree Celsius and of concentration 20% approximately).

2.4 PHOTOVOLTAIC EFFECT:

A solar cell is a semiconducting device that absorbs light and converts it into electrical energy.

The p n junction silicon cell consists of moderately p doped base substrate and a thin heavily n doped

top layer. Thin metal contacts on the surface and a plain metal layer on the back connect this

photovoltaic element to the load. If exposed to radiation, electron hole pairs are created by photons

with an energy greater than the band gap energy of the semiconductor. This is called photovoltaic

effect. The newly created charge carriers in the depletion region are separated by the existing electric

field. This leads to a forward bias of the p n junction and builds up a voltage potential called the photo

voltage. As soon as a load is connected to a cell ,this voltage will cause a current to flow through the

load.

2.5LED DRIVER:

Led driver used in our project is a step-up switching regulator, which switch the lower voltage

into a desired value. In this IC MC34063A is used for the boosting of the voltage from the battery,

which is a monolithic control circuit containing all the active function for dc to dc converters. The

device contains an internal temperature compensated reference, comparator, an oscillator with an

active peak current limit circuit, driver and an output switch.



CHAPTER 3: FEASIBILITY STUDY

The main purpose of feasibility study is to select the best system from group of similar

systems, which will work in the environment that can be afforded. Typical criteria for feasibility of a

product are accuracy, control easiness, easiness to set up manually and its total cost, which is both its

initial cost and maintenance cost. Feasibility of our project is mainly classified into,

3.1 Technical Feasibility.

3.2 Economic Feasibility.

3.3 Operational Feasibility.

3.1 Technical Feasibility.

The tracking of maximum charging current from solar panel is based on the embedded program

written on the PIC microcontroller which can be erased and used if any correction is to made on that.

The program is written on high level language so it became ease to write program.

3.2 Economic Feasibility

The project aims mainly on poor families so it must be economically feasible. The costlier part

of our project is solar panel which will cost about 160 Rs per watt, now days the government is

providing subsidies for buying solar panels. So our project becomes economically feasible.LED array

is used for the lighting purpose so it became lifelong and efficient which will decrease the usage of

current from the battery .Hence we can use a low cost battery for the use.

3.3 Operational Feasibility

User having a minimum knowledge can set up in his house. The only thing he has to look is the

position of the solar panel. It should be placed on an unshaded region. The loads attached to battery

can be controlled by simple on off switches. Loads are automatically shut off during the time of low

voltage level in the battery. These all things make our project feasible for a common man.



CHAPTER 4: SOFTWARE & HARDWARE REQUIRMENT

4.1 SOFTWARE:

Operating system : Windows/LINUX

Development tool : orcad, micro-c

4.2 HARDWARE

FIG 3: BLOCK DIGARAM OF HARDWARE

4.2.1 SOLARPANEL

FIG 4 : SOLAR CELL

SOLAR PANEL

CONTROLLER

SEPIC CONVERTER

BATTERY

LOAD



Photovoltaic cells are devices that absorb sunlight and convert that solar energy into electrical

energy. Solar cells are commonly made of silicon, one of the most abundant elements on Earth. Pure

silicon, an actual poor conductor of electricity, has four outer valence electrons that form tetrahedral

crystal lattices.

When photons (sunlight) hit a solar cell, its energy frees electron-holes pairs. The electric field

will send the free electron to the N side and hole to the P side. This causes further disruption of

electrical neutrality, and if an external current path is provided, electrons will flow through the path to

their original side (the P side) to unite with holes that the electric field sent there, doing work for us

along the way. The electron flow provides the current, and the cell's electric field causes a voltage.

With both current and voltage, we have power, which is the product of the two. By wiring solar cells

in series, the voltage can be increased; or in parallel, the current. Solar cells are wired together to form

a solar panel. Solar panels can be joined to create a solar array

I-V CHARACHTERISTIC OF SOLAR PANEL

Figure below shows the typical characteristics of a solar panel. Isc is a short-circuit current that flows

through the panel when the panel is short circuited. It is the maximum current that can be obtained from

the panel. Voc is the open-circuit voltage at the terminals of the panel. Vmp and Imp are the voltage

and current values at which maximum power can be obtained from the panel. As the sunlight reduces

the maximum current (Isc) which can be obtained, the maximum current from the panel also reduces.

FIG 5: VI CHARA OF SOLAR PANEL



4.2.2 BATTERY

In a photovoltaic power supply system, batteries are used as an energy buffer. This buffer is

necessary because the sun is not consistently available due to a variety of factors: the weather, time of

the day, and for vehicles rapidly changing insulations due to vehicle motion. Using the batteries to

store the electrical power from the solar panels in the form of chemical energy makes the generated

Energy readily available whenever it is needed, independent of the current weather

Conditions and time.

FIG 6: 12V 7Ah, BATTERY

4.2.3. CONTROLLER

PIC MICROCONTROLLER 16F873A

FIG7: MICROCONTROLLER



The microcontroller pic16f873 is a 28 pin package. It has 35 instruction set and 5 input channel 10bit

analog to digital module. It operates in frequency of dc 20 MHz and three input output ports. The

microcontroller used to provide PWM signal to SEPIC circuit. The microcontroller also interfaced

with the LCD module and the MPPT algorithm is programmed on microcontroller.

4.2.4. SEPIC CONVERTER

Single-ended primary-inductor converter (SEPIC) is a type of DC-DC converter allowing the electrical

potential (voltage) at its output to be greater than ,less than or equal to that at its input ; the output of

the SEPIC is controlled by the duty cycle of the control transistor.

A SEPIC is a similar to a traditional buck-boost converter, but has advantages of having non-inverted

output (the output voltage is of the same polarity as the input voltage), the isolation between its input

and output (provided by a capacitor in series), and true shutdown mode: when the switch is turned off,

its output drops to 0 V.

FIG 8: SEPIC CONVERTER BASIC CIRCUIT

The schematic diagram for a basic SEPIC is shown in Figure 5. As with other switched mode

power supplies (specifically DC-to-DC converters), the SEPIC exchanges energy between the

capacitors and inductors in order to convert from one voltage to another. The amount of energy

exchanged is controlled by a switch S1, which is typically a transistor such as a MOSFET; MOSFETs

offer much higher input impedance and lower voltage drop than bipolar junction transistors (BJTs),

and do not require biasing resistors (as MOSFET switching is controlled by differences in voltage

rather than a current, as with BJTs).

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

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

http://en.wikipedia.org/wiki/DC-to-DC_converter

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

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

http://en.wikipedia.org/wiki/DC-to-DC_converter

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

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

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



Continuous mode

A SEPIC is said to be in continuous-conduction mode ("continuous mode") if the current through the

inductor L1 never falls to zero. During a SEPIC's steady-state operation, the average voltage across

capacitor C1 (VC1) is equal to the input voltage (Vin). Because capacitor C1 blocks direct current (DC),

the average current across it (IC1) is zero, making inductor L2 the only source of load current.

Therefore, the average current through inductor L2 (IL2) is the same as the average load current and

hence independent of the input voltage. Looking at average voltages, the following can be written:

VIN = VL1 + VC1 + VL2 ( 5.1)

Because the average voltage of VC1 is equal to VIN, VL1 = −VL2. For this reason, the two inductors can

be wound on the same core. Since the voltages are the same in magnitude, their effects of the mutual

inductance will be zero, assuming the polarity of the windings is correct. Also, since the voltages are

the same in magnitude, the ripple currents from the two inductors will be equal in magnitude. The

average currents can be summed as follows:

ID1 = IL1 − IL2 (5.2)

When switch S1 is turned on, current IL1 increases and the current IL2 increases in the negative

direction. (Mathematically, it decreases due to arrow direction.) The energy to increase the current IL1

comes from the input source. Since S1 is a short while closed, and the instantaneous voltage VC1 is

approximately VIN, the voltage VL2 is approximately −VIN. Therefore, the capacitor C1 supplies the

energy to increase the magnitude of the current in IL2 and thus increase the energy stored in L2. The

easiest way to visualize this is to consider the bias voltages of the circuit in a d. c. state, then close S1.

FIG9: SEPIC ON CONDITION CIRCUIT

When switch S1 is turned off, the current IC1 becomes the same as the current IL1, since

inductors do not allow instantaneous changes in current. The current IL2 will continue in the negative

direction, in fact it never reverses direction. It can be seen from the diagram that a negative IL2 will

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

http://en.wikipedia.org/wiki/Steady-state



add to the current IL1 to increase the current delivered to the load. Using Kirchhoff’s Current Law, it

can be shown that ID1 = IC1 - IL2. It can then be concluded, that while S1 is off, power is delivered to

the load from both L2 and L1. C1, however is being charged by L1 during this off cycle, and will in

turn recharge L2 during the on cycle.

FIG 10: SEPIC OFF CONDITION CIRCUIT

Because the potential (voltage) across capacitor C1 may reverse direction every cycle, a non-

polarized capacitor should be used. However, a polarized tantalum or electrolytic capacitor may be

used in some cases, because the potential (voltage) across capacitor C1 will not change unless the

switch is closed long enough for a half cycle of resonance with inductor L2, and by this time the

current in inductor L1 could be quite large.

The capacitor CIN is required to reduce the effects of the parasitic inductance and internal

resistance of the power supply. The boost/buck capabilities of the SEPIC are possible because of

capacitor C1 and inductor L2. Inductor L1 and switch S1 create a standard boost converter, which

generate a voltage (VS1) that is higher than VIN, whose magnitude is determined by the duty cycle of

the switch S1. Since the average voltage across C1 is VIN, the output voltage (VO) is VS1 - VIN. If VS1 is

less than double VIN, then the output voltage will be less than the input voltage. If VS1 is greater than

double VIN, then the output voltage will be greater than the input voltage.



4.2.5.POWER SUPPLY OF MICROCONTROLLER

12V provide from battery is converted to 5V for providing Vcc for Microcontroller. Here we are

using regulator IC 7805 .

FIG 11:5V POWER SUPPLY MICROCONTROLLER

4.2.6CURRENT SENSING

The circuit is used for the low side monitoring of current .Here the voltage difference across the series

resistor is amplified and the current through it is measured with the help of microcontroller. Care

should be taken that the resistor value should be lower as possible .High resistance values cause the

power source voltage to degrade through IR loss.

4.2.7LCDMODULE

FIG 12: LCD 2X 16 DISPLAYS

This is used to display the name of the project and the parameters which we have measured.

To do so we are using a LCD panel this is HD44780U compatible series display. It can display in two

lines, each line contains 16 characters. So we can say it 16x2 matrix LCD display. It has 8 data lines

along with an R/W and RS pins. Which make it work in the either in 4 bit mode and 8 bit mode. The



contrast of the display can be controlled by the use of the potentiometer which gives the extent of the

brightness. The voltage of the third pin of the LCD used to adjusting contrast. Here we are connected

a variable resistor P1 for adjusting voltage of the 3rd

pin. The c3 and c7 are used to reject the noise

from the supply voltage. The same LCD works as 4 bit interfacing. Here this LCD work as 8bit LCD.

So we can connect D0-D7 pins of LCD connected.

FIG 13: LCD INTERFACE

LCD PIN DESCRIPTION

Table 1 : LCD PIN DISCRIPTION

PIN SYMBOL DESCRPTION

1 Vss Ground

2 Vcc +5V power supply

3 VEE Contrast adjust

4 RS RS=0 to select command register, RS=1 to

select data register

5 R/W R/W=0 for write, R/W=1 for read

6 E Enable

7 DB0 The 8-bit data bus




PIN SYMBOL DESCRPTION







15 VLed Supply for back LED

16 VGnd Ground for Back LED



CHAPTER 5: DESIGN SPECIFICATION

5.1. SOLAR PANEL

“Solar panel” provides varying voltage from 8V to 24V we require the maximum power point for

charging the battery .Solar panel is supposed to provide 1A at maximum solar intensity.

5.2. SEPIC

SEPIC is used to provide a maximum current for charging the battery. The output voltage of SEPIC

depends on the switching frequency of the PWM signal. The PWM switching is provided from the

PIC microcontroller. The switching frequency is 20khz is provided.

5.3. CURRENT & VOLTAGE SENSING

The current sensing is done by taking the voltage difference across the low value resistor. The

low value resistor is used in the range of .1ohms .The voltage across the low value resistor is provided

across the comparator IC 358. The output from the op-amp is a voltage value ranging from 0 to 5 volt.

The voltage to be sensed is taken across the voltage divider and the collected output voltage is

provided to ADC of PIC it range from 0 to 5 volt.

5.4. GATE DRIVER CIRCUIT.

The PWM from the PIC is only of 5V with this voltage the switching of the MOSFET is not

properly functioned so a transistor circuit is provide to increase the voltage level from lower value that

is from 5v to 12V in which the proper switching will be possible.

5.5. LOAD SPECIFICATION

Table 2 : LOAD USED IN OUR PROJECT

SLNO: COMPONENT SPECIFICATION CALCULATION

1 DC FAN 12V,.18A .18X4=.72A

2 RADIO 12V,.29A .29X1=.29

3 LED 3V,20mA .02X5=.1A

4 TOTAL LOAD CONSUMPTION 12V 1.11A



CHAPTER 6: HARDWARE DESIGN

6.1 CIRCUIT DIAGRAM

6.1.1 BATTERY CHARGING CIRCUIT

6.1.2 CURRENT SENSING CIRCUIT

6.1.3 MICROCONTROLLER CIRCUIT

6.1.4 LOAD DRIVING CIRCUIT

FIG 14: DETAILED BLOCK DIAGRAM



6.1.1BATTERY CHARGING CIRCUIT

FIG 15 : BATTERY CHARGING CIRCUIT

Choose a switching frequency, fs

Calculate Duty cycle

𝐷 = (𝑉𝑜𝑢𝑡 + 𝑉𝑑) ÷ (𝑉𝑖𝑛 + 𝑉𝑜𝑢𝑡 + 𝑉𝑑) (6.1.1)

Assuming 100% efficiency, the duty cycle D for a SEPIC converter operating in

CCM is given by D

Provide 12V for gate

Capacitor design.

𝐶𝑜𝑢𝑡 ≥ (𝐼out ×D)÷(Vripple×0.5×fsw) (6.1.2)

Inductor Design

𝐿1 = 𝐿2 = 𝐿 = 𝑉𝑖𝑛 𝑚𝑖𝑛 × 𝐷𝑀𝑎𝑥 ÷ (∇𝐼𝑙 × 𝑓𝑠𝑤)

J2

Battery

12

R15

47K

R16

10K

C100.1uF/16V

PWM

CS_IN

D3

1N4148

D4

GREEN LED

R20

10K

R172.2K

D7

1N4007

Q3BC548

J1

Solar Pannel

12

R26

D1

1N4148

D2

ORANGE LED

R112.2K

L1

500uH

F1

FUSE

D5

1N4007

F2

FUSE

C1

1000uF

/35V

C2

1000uF

/35V

C40.1uF/50V

VS_PV

VBAT

U6

L7805

VIN1

VOUT3

R25

47K

R19

10K

Q2

IRFZ44

C110.1uF/16V

VBAT

VS_BT

L2

500uH

C12

470uF/25V

LS2

RELAY SPDT

35

412

D8

1N4007

+12V

Q5BC548B

R36

1K

VBAT

LOAD

J4

LOAD

12

F3FUSE

VCC

C130.1uF/50V

C6

470uF

/25V

C7

470uF

/25V

C90.1uF/50V

D6 BA159

VBAT

D12

RED LED

R35

1K

R14

0.33 OHM



6.1.2CURRENT SENSING CIRCUIT

FIG16: CURRENT SENSING

6.1.3MICROCONTROLLER CIRCUIT

FIG 17 : MICROCONTROLLER

0

R3

10k

R4

1k

-

+

U3A

LM358

3

21

84

VCC

CS_INCS_OUT

0R23

10k

C16

0.1uF

LOAD

CS_OUT

VS_PV PWM

R22

10K

13

2

16*2 LCD Module

D0

7

D1

8

D2

9

D3

10

D4

11

D5

12

D6

13

D7

14

RS

4

R/W

5

EN

6

VCC15

GND1 CON

3VCC2

GND16

VCC

U1

PIC16F73

MCLR/VPP/THV1

RA0/AN02

RA1/AN13

RA2/AN2/VREF-4

RA3/AN3/VREF+5

RA4/T0CKI6

RA5/SS/AN47

OSC1/CLKIN9

OSC2/CLKOUT10

RC0/T1OSO/T1CKI11

RC1/T1OSI/CCP212

RC2/CCP113

RC3/SCK/SCL14

RC4/SDI/SDA15

RC5/SDO16

RC6/TX/CK17

RC7/RX/DT18

VDD20

RB0/INT21 RB122 RB223 RB3/PGM24 RB425 RB526 RB6/PGC27 RB7/PGD28

Y1

20MHz Cry stal

MCLR

C2310uF

R1810K

R24

1K

C14

22pF

C15

22pF

VCC

VCC

VS_BT



6.1.4 LED DRIVER CIRCUIT

FIG 18: LED DRIVER

It is basically derived from a basic step-up switching regulator, which is shown in figure14 .Energy stored

in the inductor during the time that transistor Q1 is in the “on” state. Upon turn- off, the energy is transferred in

series with Vin to the output filter capacitor and load.

FIG 19: BASIC STEPUP SWITCHING REGULATOR CIRCUIT

This configuration allows the output voltage to be set to any value greater than that of the input

by the following relationship:

Vout = Vin (ton/toff) + Vin or Vout = Vin (ton/toff+1) (6.1.4)

In our project the battery provides only 12 v, but we require 24 v to light up led lamp.

For this purpose we have to convert 12 v to 24 v. so we use a boost led driver circuit for the

conversion.

J1

CON2

12R24

200K

R25

10K

U7

MC34063A

COMP5

TCAP3

VCC6

GND4

DC8

PK7

SWC1

SWE2

C15100uF/63V

L2

1mH

C10100uF/63V

R260.47 ohm

R27

220 ohm

C11220pF

D7

1N5819 / BA159

C1247uF/63V

C130.1uF

BT2

12V BATTERY



CHAPTER 7: SOFTWARE DESIGN

7.1 ALGORITHM

1. Start

2. Initialize ports of microcontroller , LCD and PWM

3. Track

4. Measure battery voltage and battery current.

5. Display on LCD

6. If panel voltage is changed more than a threshold, track again

7. If battery voltage is less than the lower limit switch of the load.

8. If battery voltage reached maximum, turn off charging

9. Go to line 4.

Track

1. Set PWM to zero

2. Measure panel voltage, battery voltage and battery current.

3. Display on LCD

4. If panel voltage is less than limit, stop charging

5. Save the maximum charging current

6. Increase PWM

7. Continue to line 2 until maximum PWM is reached.

8. Set pwm to maximum current value.

9. Return



7.2 FLOW CHART

yes

YES

NO

NO YES

Switch off the load

Track

Measure battery

voltage and battery

current

start

Initialize ports of microcontroller, LCD

and PWM

Stop charging

Display on LCD

If panel

voltage is >

threshold

Track

Major Project Report Solar Powered Home

MAJOR PROJECT 2010-2011

SOLAR POWERED HOME

SUBMITTED BY: GROUP 7H

S8 EC

If battery

voltage is <

lower limit

If battery

voltage is >

upper limit

Measure panel voltage and

panel current

Switch on the load



YES

NO

NO

YES

FIG 20: FLOW CHART SOLAR POWERED HOME

Set PWM =0

Stop charging

Save the maximum charging

current

Measure panel

voltage, battery

voltage and battery

current

Display on LCD

If panel

voltage is <

lower limit

Increase PWM

If PWM

Reaches

maximum

Set PWM to

maximum current value

RETURN

Track



CHAPTER 8: IMPLEMENTATION/ TECHNOLOGICAL DEVELOPMENT

Our project is based on the electrical requirement of a financially poor family living in a remote

place this can also been useful for middle class family during the time of power failure. Since the

amount of output current from a solar panel depends directly on the amount of light falling on it so the

solar panel should be placed on where more intensity of sun light is supposed to fall. In normal case it

is placed on the roof of the house. Radio, DC fan and LED lamp should be placed on proper place to

provide maximum output. Solar panel is having a glass cover over it so care should be given on

placing it.

The technological development should be made on the dimming of LED lamp according to

the luminous inside the room this can be provided by using suitable PWM signals. New technological

advancement in LED light can cause better future in this field. By providing maximum tracking of

current from solar panel increases the efficiency of our project, hence improvement and more studies

on this technology may end up in a great success.



CHAPTER 9: CONCLUSION

9.1TESTING AND RESULT

The designed hardware circuitry is implemented on a PCB and the software coding is done in

very efficient and fast embedded C language. The entire implementation is checked and it proves our

effort of a great success. We believe our project is very suitable for the next generation for solving the

electrical energy requirement. The design has to be tested for checking the performance, unless the

project is tested positive, nothing has been gained by doing it.

9.2 ENHANCEMENT

We can enhance this project by introducing lens frame in front of the solar panel to concentrate

the sun light intensity. By providing a suitable heat sink for the panel we can increase the efficiency

of the system. We can use this project in motor vehicles to provide the electrical requirement.

9.3 LIMITATIONS

One of the limitation in our system is that if there is no required amount of light intensity ,that is

in rainy days we are not able to provide charging current for the battery. The surface of solar panel

should be clean to have maximum efficiency so it is less efficient in desert areas where the dust

amount is very high. In order to provide voltage to run high load applications we require a large solar

panel, that is the output voltage from a solar panel is directly proportional to its area.The initial cost is

very high for the components like solar panel and battery. The voltage drop across the current sensing

circuit may reduce the efficiency of the system. The increases in temperature of the solar panel

reduces the efficiency . Solar panel provides an appropriate voltage up to 30 degree Celsius.



APPENDIX 1

COMPONENT SPECIFICATION WITH COST

Table 3 COMPONENTS USED

SL.NO COMPONENTS SPECIFICA

TIONS

Rupees

1 RESISTORS

R11 2.2K 0.25

R12,R14 1R 0.5

R3,R7,R5,R26,R2

3,R22,R18,R19,R1

6

10K 2.25

R4,R6,R24,R21 1K 1.0

R15,R25 47K .5

2 CAPACITORS

C17,C16 .1 µF 1

C23 10MF .5

C14,C12,C15 22PF 1.5

C-in 47MF .5

C-out 100µF .5

C12 47MF/16V .5

C11 0.1µF .5

U1 PIC

16F873A

150

U2 LM358 15

4 LCD 16x2 150

5 SOLAR PANEL 10W,0.83A 2000

6 BATTERY 7AH 665

7 MOSFET IRFZ44 15

8 DIODE BA159 8

D1,D3 IN4148 2

D2 RED LED 3



D4 GREEN LED 3

D5,D7 IN4007 2

9 INDUCTOR

L1,L2 526 µF 16

10 WHITE LED 3V 1.25 X 40 =50

11 LED BOX 40HOLE 72

12 DC FAN 12V,.18A 26X4=104

13 RADIO 12V 120

TOTAL 3390



APPENDIX2

PCB LAYOUT

FIG 21:PCB LAYOUT OF CHARGING CIRCUIT

FIG 22: PCB LAYOUT OF LED DRIVER



APPENDIX 3

REFERENCES

Basic for PIC microcontrollers,Nebojsa Matic

Power electronics circuits devices and applications.

C programming for Embedded systems, Kirk Zurell

Electronics Lab Manual, K.A.Navas,first edition

PIC microcontroller and embedded system Mazidi

www.mikroelectronica.com

www.onsemi.com

http://www.mikroelectronica.com/

http://www.onsemi.com/

April 11

Documents

solar energy

solar panels

solar cell

solar powered home chapter

cherthala major project

project objective

chara of solar panel

light energy