3-1 Basic Principles.pdf

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Module 3Module 3

Solar PhotovoltaicSolar PhotovoltaicOsamu Iso

Workshop on Renewable Energies

November 14-25, 2005

Nadi, Republic of the Fiji Islands

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3.Solar Photovoltaic3.Solar Photovoltaic

1. Basic principles of PV1-1. Mechanism of generation1-2. Various type of PV cell1-3. Installation example1-4. Basic characteristic

2. Potential assessment2-1. Basic principle of assessment2-2. Insolation measurement

2-3. Estimation of annual generation power 2-4. Case practice

3. System configuration3-1. Cells, Modules and Arrays3-2. Type of system ( Grid interconnection or not )3-3. Power conditioner (Control system)3-4. Batteries3-5. Wiring3-6. Some tips for system design3-7. Case practice

• Contents


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4. Example of equipment price

4-1. PV module

4-2. Battery

4-3. Power conditioner

5. Design example of Solar Home System ( SHS in Indonesia )

5-1. E7 Climate Change Projects

5-2. Renewable Energy Supply Systems

5-3. Reference

6. Design example of independent PV system for small community

6-1. Basic condition and planning steps

6-2. Basic load estimation

6-3. System capacity design

6-4. Backup generator 6-5. Merits of small grids (compare with SHS )

6-6. Case practice

• Contents

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7. Design example of grid-connected PV system and analysis of

7-1. String characteristics

7-2. Energy production

7-3. Observations and analysis

8. Design example of grid interconnected PV system ( Philippine )

8-1. Introduction

8-2. Outline of Photovoltaic system

8-3. Lessons Learned8-4. Photo and Drawings

9. Maintenance

• Contents


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3. Solar Photovoltaic3. Solar Photovoltaic

1. Basic principles of PV

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1.Basic principle of PV1.Basic principle of PV

1. Basic principles of PV

1-1. Mechanism of generation

1-2. Various type of PV cell

1-3. Installation example

1-4. Basic characteristic

1-5. Case study

• Contents


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A d v a n t a g e s (1) Clean

Solar energy is a clean energy. It emits very smallamount of carbon gases or sulfur oxides.

(2) InfiniteSolar energy is infinite and permanent.

D i s a d v a n t a g e s

(1) Volatile in outputThe amount of sunlight varies according to seasonsand weather. Therefore, generating electric power to meet the demand anytime is impossible.

(2) Low in power densityRegardless of the vast solar energy coming down tothe earth, power density in sunlight can be as low as1,000 watts/m2. Acquisition of vast amount ofenergy needs vast surface area of the solar cell.

22--11--1. Principle and system configuration1. Principle and system configuration

• Characteristics of Photovoltaic

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22--11--2. Installed Capacity in the World2. Installed Capacity in the World

• Trends in Photovoltaic capacity in the world

0

200,000

400,000

600,000

800,0001,000,000

1,200,000

1,400,000

1,600,000

1,800,000

2,000,000

92 93 94 95 96 97 98 99 00 01 02 03

Year

1,809,000kW

Installed capacityper year Accumulated

capacityInstalled capacityper year

Accumulatedcapacity

Cap a

city(kW)

Other

8.2%

Australia

2.9%

Germany 22.7%

USA

15.2%

Netherlands

2.5%

Italy 1.4%

Accumulated capacity[MW]

at the end of 2003

JAPAN

47.5%


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+

+

+ +

- -

-

-

Photo Voltaic cell

Electrode

P-Type Semiconductor

N-Type Semiconductor

Reflect-Proof Film

Electrode

Solar Energy

Load

E l e c t r i c C u r r e n t

11--1. Mechanism of generation1. Mechanism of generation

• Mechanism of generation

The solar cell is composed of a P-type semiconductor and an N-typesemiconductor. Solar light hitting the cell produces two types of electrons,

negatively and positively charged electrons in the semiconductors.Negatively charged (-) electrons gather around the N-type semiconductor while positively charged (+) electrons gather around the P-typesemiconductor . When you connect loads such as a light bulb, electriccurrent flows between the two electrodes.

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• Direction of current inside PV cell

P

N

Current appearsto be in the

reverse direction ?

• Inside current of PV cell looks like

“Reverse direction.” Why?

?

• By Solar Energy, current is pumpedup from N-pole to P-pole.

• In generation, current appears reverse.

It is the same as for battery.

P

N

Looks likereverse


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• Voltage and Current of PV cell ( I-V Curve )

(V)

(A)

Voltage(V)

C u r r e n t ( I )

P

N

A

Short Circuit

Open Circuit

P

N

V

about 0.5V

(Silicon)

High intensity insolation

•Voltage on normal operation point

0.5V (in case of Silicon PV)

•Current depend on

- Intensity of insolation

- Size of cell

•Voltage on normal operation point

0.5V (in case of Silicon PV)

•Current depend on

- Intensity of insolation

- Size of cell

Low intensity insolation

Normal operation point

(Maximum Power point)

I x V = W

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• Typical I-V Curve

(V)

(A)

Voltage(V)

C u r r e n t ( I )

0.49 V

St and ar d insolat ion 1.0 k W / m2

0.62 V

4.95A

5.55A

Depend on type

of cell or cell-

material

( Si = 0.5V )

Depend on cell-size

Depend on

Solar insolation


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• Illegal use

If you charge PV by another power source

and try to make normal direction current,

the PV will heat up and cease to function.

Do not charge PV by another power source.

Force to make normal

direction current

Do not create a short circuit when sunshine is being received.

P

N

If a short circuit is created during insolation,

large current will heat up PV cell and cellwill cease to function.

P

N

+

-

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CrystallineCrystalline

Non-crystallineNon-crystalline

Single crystalSingle crystal

Poly crystallinePoly crystalline

AmorphousAmorphous

Gallium Arsenide (GaAs)Gallium Arsenide (GaAs)

Conversion Efficiencyof Module

Conversion Efficiencyof Module

10 - 17%10 - 17%

10 - 13%10 - 13%

7 - 10%7 - 10%

18 - 30%18 - 30%

Conversion Efficiency =Electric Energy Output

Energy of Insolation on cellx100%

Dye-sensitized TypeDye-sensitized Type

Organic Thin Layer TypeOrganic Thin Layer Type

7 - 8%7 - 8%

2 - 3%2 - 3%

11--2.2. Various type of PV cellVarious type of PV cell

• Types and Conversion Efficiency of Solar Cell

Silicon

Semiconductor

Silicon

Semiconductor

CompoundSemiconductor CompoundSemiconductor SolarCell

SolarCell

Organic

Semiconductor

Organic

Semiconductor

(Note) Single crystal = Mono crystal


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• Crystal cell (Single crystal and Poly crystalline Silicon)

Single crystal Poly crystalline


10cm 10cm

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• Surface of PV cell


Front Surface

(N-Type side)

• Aluminum Electrode(Silver colored wire)

• To avoid shading,electrode is very fine.

Anti reflection film

(Blue colored film)

• Back surface is P-type.

• All surface isaluminum electrodewith full reflection.


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Single crystal Poly crystalline

120W

(25.7V ,4.7A)

1200mm

800mm800mm

1200mm


• PV Module (Single crystal, Poly crystalline Silicon)

(3.93ft)

（2.62ft）

（3.93ft

）

(3.93ft)

128W

(26.5V ,

4.8A)

Formed by melting high purity

silicon, then sliced very thinly and

processed into solar panel.

“Metal silicon pure enough to

manufacture solar cell”

is poured into a mold and crystallized.

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• Single crystal silicon production process

Same as IC’s process Pulled up veryslowly to make

perfect crystal

• Perfect crystal growing is possible.

• Efficiency is high.

• Process speed is low.

• Price is high.

• Perfect crystal growing is possible.

• Efficiency is high.

• Process speed is low.

• Price is high.


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• Poly crystalline silicon production process

FragmentationFragmentation

MeltingMelting

Re-crystallizingRe-crystallizing

CoolingCooling

CuttingCutting

SlicingSlicing

Cool slowly to make

larger crystal

• Crystallization is not perfect.

• Efficiency is lower than single crystal.

• Process speed relatively higher.

• Price is lowerthan single crystal.

• Crystallization is not perfect.

• Efficiency is lower than single crystal.

• Process speed relatively higher.

• Price is lower than single crystal.

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• Improvement of Poly crystalline production process

Molten silicon

Meltingpot

Cooling block

Ideal control ofingot cooling

process

Heater control

Avoid pollution

Cool slowly,

carefully

Crack ofcrystallinecauses lawefficiency

Improvement

To grow big crystalline cell


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Glass substrate type Film substrate type


• Amorphous (Non-Crystalline) Silicon Solar Panels

• Manufactured by applying thin-layer manufacturing technology forsemiconductor

• Good for mass production. Price is lower than crystal type

• Efficiency is lower than crystal type

• Very flexible. Easy to fit on any shape of substrate.

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• A-Silicon production processLike “Rotary printer” for news paper (good for mass production)

PunchingSerial-hole forming

Metal electrode forming PunchingCorrecting electrode forming

Amorphous siliconforming

Transparent electrodeforming

Back patternelectrode forming

Electrode patterning

LASER patterner

Lamination

Protective film

Plasma formingprocess

( Vacuumed chamber )

SiH4 + O2 Si + 2H2O


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• Comparison of type

Price Efficiency 1 W size Current Production

Single crystal High 10 - 17 % 1.0 about 30 %

Poly crystalline Medium 10 – 13 % 1.3 about 60 %

Amorphous Low 7 – 10 % 1.7 about 10 %

(Reference)

PV cell size for1 W power generation

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• Shear of type

1018.4

10.2

0

9.9

5.8

10.1

2.7

5

5.4

65.4

10.250.3

73.9 56

18.8

61.3

36.8

21.128.7

1

2

3

4

5

6

7

8

9

1

Japan USA EU Others Total

Single Crystal

Poly Crystalline

Amorphous

Others


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• Sun shine spectrum and PV

Wavelength (nm)

R e l a t i v e S p e c t r a l r e s p o n s e

I r r a d i a n c e ( W / m )

Sun SpectrumCrystalline Silicon

Amorphous Silicon

Visible light Infra RedUltra Violet

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• Production share of the world market

1,194.7MW

(2004)

Japan

50.3%EU

26.3%

USA

11.6%

Others

11.7%SHARP27.1%

KyoCera8.8%

SANYO5.4%


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Refining

99.99999999 %

Raw SiliconSemiconductor

Wafer for ICIC Chip

Refining

99.9999 %

PV

Garbage,Edge,Inferior IC

Under developing

(Expensive now)


• How to make PV’s silicon

(Melt again)

To get cheaper silicon, recycled silicon is used for PV.

Amount of raw material is affected by IC industry’s production

To get cheaper silicon, recycled silicon is used for PV.

Amount of raw material is affected by IC industry’s production

Refining purity is lower than IC

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• Use insolation efficiently and reduce materials

Anti reflectioncoating

Back side reflectiveelectrode

Slice thin wafer

Wire saw

Low resistance finepatterned front electrode

Texturized surface

( like a pyramid )

Polycrystalline ingot

Poly Si wafer

fine wire saw

Reduce reflection


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• Hierarchy of PV

2 – 3 W

100 - 200 W

10 - 50 kW

Cell

Array

Module,Panel

Volt Ampere Watt Size

Cell 0.5V 5-6A 2-3W about 10cm

Module 20-30V 5-6A 100-200W about 1m

Array 200-300V 50A-200A 10-50kW about 30m

6x9=54 (cells) 100-300 (modules)

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• Roughly size of PV Power Station.

In this conference room, how much PV panel we can install?

1 kw PV need 10 m21 kw PV need 10 m2 Please

remember

10m(32feet)

2 0 m ( 6 5 f e e t

)

Conference

Room

(We are now)

Our room has about 200 m2

We can install about

20 kW PV in this room


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11--3.3. Installation exampleInstallation example

• Roof top style ( Residence )

•Main grid connected

•AC supply

•No battery

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• Roof top style ( School , Community-center building)

•Main grid connected

•AC supply

•With battery for emergency


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• Roof top style ( Off grid power supply )

Relay station on top of mountain Advertising sign beside highway

•No Grid connection

•AC supply•With battery

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• Roof top style ( Mountain lodge)

1.2kW system

Inverter and controller


•AC supply

•With battery


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• Stationary style

Site: Mongolia

Installation: May & June in 1999

Purpose: For lighting, refrigerator

and outlet in a hospital

Solar cell capacity: 3.4kW

Wind Power capacity: 1.8kW

Inverter capacity: 5kVA

•Independent small Grid connection

•AC supply

•With battery

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The system supplies alternating currentelectricity to 240 residences in 3 villages.

*Solar cell capacity: 151kW (total of 3 villages)

*Type of solar cell: single-crystal

*Inverter capacity: 100kW

*Battery:7,700kWh (total of 3 villages)

*Year of installation: 1986

22--11--3. Example3. Example

• Electrification of a village (in Thailand)

• Small Grid connection(3 villages grid)

• AC supply

• With battery


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• Solar Home System (SHS)

Solar array

Solar arraySolar array

Solar array

Controller

Light

Storage battery


•DC supply

•With battery

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11--4.4. Basic CharacteristicBasic Characteristic

• I / V curve and P-Max control

P

N

A

V

• To obtain maximum power, current

control (or voltage control) is veryimportant.

P- Max controlP- Max control

• “Power conditioner” (mentioned

later) will adjusts to be most suitablevoltage and current automatically.

(V)

(A)

Voltage(V)

C u r r e n t ( I )

I x V = W

P2

PMAX

P1

Vpmax

Ipmax

Power curve

I/V curve


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• Estimate current and voltage by I / V curve

(V)

(A)

Voltage(V)

C u r r e n t ( I )

12

10

8

6

4

2

0

0 0.1 0.2 0.3 0.4 0.5 0.6

)(05.0 Ω= R

I

V R =

P

N

A

)(05.0 Ω= R

If the load has 0.05 ohm resistance,

Circuit current is 10 AVoltage is 0.5 V

Then power is 10x0.5=5 W

R e s i s t a n

c e c h a

r a c t e r

PV character

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• I / V curve vs. Insolation intensity

P

NP

N

Mismatch

5A

1A

P

NP

N

BypassDiode

5A

1A 4A(V)

(A)

C u r r e n t ( I )

High intensity insolation

Low intensity insolation

I x V = W

5A

1A

•Current is affected largely by change

of insolation intensity.

•Partially shaded serial cell will

produce current mismatch.

Bypass Diode


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• Temperature and efficiency

4

6

8

1

12

14

1 2 3 4 5 6 7 8 9 1

Module Temperature (deg.C)

E f f i c i e n c y ( % )

Crystalline cell

Amorphous cell

0.25 ( % / deg)

Typical(25C)

Summer timeon roof top

(65C)

2%down 0 .4 – 0 .5 ( % / d e g )

•When module temperature rises up, efficiency decreases.

•The module must be cooled by natural ventilation, etc.

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11--5.5. Case studyCase study

• Maximum power control

P

N

P

N

P

N

)(05.0 Ω= R

)(10.0 Ω= R

)(02.0 Ω= R

Q : Calculate loaded power to resistance.

( I / V curve is next page)

(Work)


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(V)

(A)

Voltage(V)

C u r r e n t ( I )

12

10

8

6

4

2

0

0 0.1 0.2 0.3 0.4 0.5 0.6

)(05.0 Ω= R

I

V R =

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(V)

(A)

Voltage(V)

C u r r e n t

( I )

12

10

8

6

4

2

0

0 0.1 0.2 0.3 0.4 0.5 0.6

)(05.0 Ω= R

)(02.0 Ω= R

)(10.0 Ω= R

I

V R =

)(58.22.1123.0 W P =×=

)(31.37.558.0 W P =×=

)(00.50.1050.0 W P =×=


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P

N

P

N

P

N

)(05.0 Ω= R

)(10.0 Ω= R

)(02.0 Ω= R

Q : Calculate loaded power to the resistance.


)(58.22.1123.0 W P =×=

)(00.50.1050.0 W P =×=

)(31.37.558.0 W P =×=

Maximum

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• Bypass Diode

Q : Calculate maximum power of each system.

a : No bypass diode.

b : With bypass diode.


P

NP

N

P

NP

N

System “a” System “b”

(Work)


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• Bypass Diode

(V)

(A)

Voltage(V)

C u r r e n t ( I )

12

10

8

6

4

2

0

0 0.1 0.2 0.3 0.4 0.5 0.6

P1max (0.5V,10A)

P2max (0.5V,4A)

PXmax (0.6V,3A)

High insolation intensity

Low insolation intensity

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• Bypass Diode

(V)

(A)

Voltage(V)

C u r r e n t

( I )

12

10

8

6

4

2

0

0 0.1 0.2 0.3 0.4 0.5 0.6

P1max (0.5V,10A)

P2max (0.5V,4A)

PXmax (0.6V,3A)



For system “a”

)(8.136.01 W Pa =×=

)(8.136.02 W Pa =×=

3.6 W


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• Bypass Diode

(V)

(A)

Voltage(V)

C u r r e n t ( I )

12

10

8

6

4

2

0

0 0.1 0.2 0.3 0.4 0.5 0.6

P1max (0.5V,10A)

P2max (0.5V,4A)

PXmax (0.6V,3A)



For system “b”

)(0.5105.01 W Pb =×=

)(0.245.02 W Pb =×=

7.0 W

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• Bypass Diode

Q : Calculate maximum power of each system.

a : No bypass diode.

b : With bypass diode.


P

NP

N

P

NP

N

System “a” System “b”

3A10A

6A4A

1.8 W

1.8 W

Total = 3.6 W

5.0 W

2.0 W

Total = 7.0 W


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• Temperature vs. Efficiency

4

6

8

2

4

2 3 4 5 6 7 8 9



Crystalline cell

Amorphous cell

0.25 ( % / deg)

Typical(25C)


(65C)

2%down 0 .4 – 0 .5 ( % / d e g )

4

6

8

2

4

2 3 4 5 6 7 8 9



Crystalline cell

Amorphous cell

0.25 ( % / deg)

Typical(25C)


(65C)

2%down 0 .4 – 0 .5 ( % / d e g )

Q: Suppose there is a 50 kW Crystalline PV system.

If surface temperature rises to 65ºC, what is the system

capacity?

(Work)

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• Temperature vs. Efficiency

4

6

8

2

4

2 3 4 5 6 7 8 9


E f f i c i e n c y

( % )

Crystalline cell

Amorphous cell

0.25 ( % / deg)

Typical(25C)


(65C)

2%down 0 .4 – 0 .5

( % / d e g )

4

6

8

2

4

2 3 4 5 6 7 8 9


E f f i c i e n c y

( % )

Crystalline cell

Amorphous cell

0.25 ( % / deg)

Typical(25C)


(65C)

2%down 0 .4 – 0 .5

( % / d e g )

)(3.4213

1150 kW =×

Approx. 15% down

13

11

Q: Suppose there is a 50 kW Crystalline PV system.

If surface temperature rises to 65ºC, what is the systemcapacity?

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3-1 Basic Principles.pdf