Module 3
Solar Photovoltaic
Osamu Iso
e7 / PPA Workshop on Renewable Energies
22-Nov-05 (17:52)
Workshop on Renewable Energies
November 14-25, 2005
Nadi, Republic of the Fiji Islands
3.Solar Photovoltaic
• Contents
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
2. Potential assessment
2-1. Basic principle of assessment
2-2. Insolation measurement
2-3. Estimation of annual generation power
2-4. Case practice
3. System configuration
3-1. Cells, Modules and Arrays
3-2. Type of system ( Grid interconnection or not )
3-3. Power conditioner (Control system)
3-4. Batteries
3-5. Wiring
3-6. Some tips for system design
3-7. Case practice
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3.Solar Photovoltaic
• Contents
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
e7 / PPA Workshop on Renewable Energies
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3.Solar Photovoltaic
• Contents
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 Learned
8-4. Photo and Drawings
9. Maintenance
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3. Solar Photovoltaic
1. Basic principles of PV
e7 / PPA Workshop on Renewable Energies
22-Nov-05 (17:52)
5
1.Basic principle of PV
• Contents
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
6
3
Advantages
• Characteristics of Photovoltaic
Disadvantages
22-Nov-05 (17:52)
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2-1-1. Principle and system configuration
(1) Clean
Solar energy is a clean energy. It emits very small
amount of carbon gases or sulfur oxides.
(2) Infinite
Solar energy is infinite and permanent.
(1) Volatile in output
The amount of sunlight varies according to seasons
and weather. Therefore, generating electric power
to meet the demand anytime is impossible.
(2) Low in power density
Regardless of the vast solar energy coming down to
the earth, power density in sunlight can be as low as
1,000 watts/m2. Acquisition of vast amount of
energy needs vast surface area of the solar cell.
2-1-2. Installed Capacity in the World
• Trends in Photovoltaic capacity in the world
2,000,000
Capacity (kW)
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Italy 1.4%
1,800,000 Netherlands
2.5%
1,600,000
Australia
2.9%
1,400,000
1,200,000
1,000,000
800,000
600,000
Other
8.2%
1,809,000kW
JAPAN
47.5%
USA
15.2%
Accumulated
capacity
Installed capacity
Accumulated
per
year
Installed
capacity
capacity
Germany 22.7%
per year
Accumulated capacity[MW]
at the end of 2003
400,000
200,000
0
92
93
94
95
96
97
98
99
00
01
02
03
Year
8
4
• Mechanism of generation
The solar cell is composed of a P-type semiconductor and an N-type
semiconductor. 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-type
semiconductor. When you connect loads such as a light bulb, electric
current flows between the two electrodes.
e7 / PPA Workshop on Renewable Energies
Electrode
Reflect-Proof Film
Solar Energy
N-Type Semiconductor
+
+
-
+
-
+
-
P-Type Semiconductor
Load
-
Electrode
Electric Current
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1-1. Mechanism of generation
Photo Voltaic cell
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1-1. Mechanism of generation
• Direction of current inside PV cell
• Inside current of PV cell looks like
“Reverse direction.” Why?
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P
?
• By Solar Energy, current is pumped
up from N-pole to P-pole.
• In generation, current appears reverse.
It is the same as for battery.
N
P
Current appears
to be in the
reverse direction ?
Looks like
reverse
N
10
5
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1-1. Mechanism of generation
• Voltage and Current of PV cell ( I-V Curve )
P
•Voltage
•Voltageon
onnormal
normaloperation
operationpoint
point
0.5V
0.5V(in
(incase
caseof
ofSilicon
SiliconPV)
PV)
A
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•Current
•Currentdepend
dependon
on
--Intensity
Intensityof
ofinsolation
insolation
--Size
Sizeof
ofcell
cell
N
Short Circuit
High intensity insolation
Current(I)
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(A)
Normal operation point
(Maximum Power point)
P
Low intensity insolation
V
IxV=W
N
(V)
Voltage(V)
Open Circuit
about 0.5V
(Silicon)
11
1-1. Mechanism of generation
• Typical I-V Curve
(A)
5.55A
Depend on cell-size
Standard in
solation 1.0
kW/m2
Depend on
Solar insolation
Depend on type
of cell or cellmaterial
( Si = 0.5V )
Current(I)
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4.95A
(V)
Voltage(V)
0.49 V 0.62 V
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1-1. Mechanism of generation
• Illegal use
Do not charge PV by another power source.
e7 / PPA Workshop on Renewable Energies
P
N
+
-
If you charge PV by another power source
and try to make normal direction current,
the PV will heat up and cease to function.
Force to make normal
direction current
Do not create a short circuit when sunshine is being received.
P
If a short circuit is created during insolation,
large current will heat up PV cell and cell
will cease to function.
N
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1-2. Various type of PV cell
• Types and Conversion Efficiency of Solar Cell
Crystalline
Crystalline
Silicon
Silicon
Semiconductor
Semiconductor
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Conversion
Conversion Efficiency
Efficiency
of
of Module
Module
(Note) Single crystal = Mono crystal
Single
Single crystal
crystal
10
10 -- 17%
17%
Poly
Poly crystalline
crystalline
10
10 -- 13%
13%
Non-crystalline
Non-crystalline
Solar
Solar
Cell
Cell
Compound
Compound
Semiconductor
Semiconductor
Organic
Organic
Semiconductor
Semiconductor
Amorphous
Amorphous
Gallium
Gallium Arsenide
Arsenide (GaAs)
(GaAs)
77 -- 10%
10%
18
18 -- 30%
30%
Dye-sensitized
Dye-sensitized Type
Type
77 -- 8%
8%
Organic
Organic Thin
Thin Layer
Layer Type
Type
22 -- 3%
3%
Electric Energy Output
x 100%
Conversion Efficiency =
Energy of Insolation on cell
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1-2. Various type of PV cell
• Crystal cell (Single crystal and Poly crystalline Silicon)
10cm
Single crystal
10cm
Poly crystalline
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1-2. Various type of PV cell
• Surface of PV cell
• Aluminum Electrode
(Silver colored wire)
• To avoid shading,
electrode is very fine.
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Anti reflection film
(Blue colored film)
Front Surface
(N-Type side)
• Back surface is Ptype.
• All surface is
aluminum electrode
with full reflection.
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1-2. Various type of PV cell
• PV Module (Single crystal, Poly crystalline Silicon)
Single crystal
Poly crystalline
128W
120W
(26.5V ,
4.8A)
(25.7V ,
4.7A)
1200mm
1200mm
（3.93ft
）
(3.93ft)
800mm (3.93ft)
800mm （2.62ft）
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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1-2. Various type of PV cell
• Single crystal silicon production process
Same as IC’s process
Pulled up very
slowly to make
perfect crystal
•• Perfect
Perfectcrystal
crystalgrowing
growingis
ispossible.
possible.
•• Efficiency
Efficiencyis
ishigh.
high.
•• Process
Processspeed
speedisislow.
low.
•• Price
is
high.
Price is high.
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1-2. Various type of PV cell
• Poly crystalline silicon production process
Fragmentation
Fragmentation
Cooling
Cooling
Melting
Melting
Cutting
Cutting
Re-crystallizing
Re-crystallizing
Slicing
Slicing
Cool slowly to make
larger crystal
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1-2. Various type of PV cell
• Improvement of Poly crystalline production process
To grow big crystalline cell
Molten silicon
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•• Crystallization
Crystallizationis
isnot
notperfect.
perfect.
•• Efficiency
is
lower
Efficiency is lowerthan
thansingle
singlecrystal.
crystal.
•• Process
speed
relatively
Process speed relativelyhigher.
higher.
•• Price
Priceis
islowerthan
lowerthansingle
singlecrystal.
crystal.
Crack of
crystalline
causes law
efficiency
Avoid pollution
Heater control
Melting
pot
Cooling block
Cool slowly,
carefully
Improve
ment
Ideal control of
ingot cooling
process
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1-2. Various type of PV cell
• Amorphous (Non-Crystalline) Silicon Solar Panels
• Manufactured by applying thin-layer manufacturing technology for
semiconductor
• 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.
Film substrate type
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Glass substrate type
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1-2. Various type of PV cell
• A-Silicon production process
Like “Rotary printer” for news paper (good for mass production)
Punching
Serial-hole forming
Metal electrode forming
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SiH4 + O2
Si + 2H2O
Punching
Correcting electrode forming
Plasma forming
process
( Vacuumed chamber )
LASER patterner
Amorphous silicon Transparent electrode
forming
forming
Back pattern
electrode forming
Protective film
Electrode patterning
Lamination
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1-2. Various type of PV cell
• Comparison of type
Single crystal
Price
Efficiency 1 W size Current Production
High
10 - 17 %
1.0
about 30 %
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(Reference)
Poly crystalline Medium 10 – 13 %
1.3
about 60 %
Amorphous
1.7
about 10 %
Low
7 – 10 %
PV cell size for
1 W power generation
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1-2. Various type of PV cell
• Shear of type
100%
90%
18.8
21.1
36.8
80%
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70%
28.7
Single Crystal
61.3
60%
50%
40%
10.2
30%
20%
10%
0%
Poly Crystalline
65.4
50.3
73.9
56
10.1
5.8
10
Japan
18.4
2.7
10.2
USA
EU
5
0
Others
5.4
9.9
Amorphous
Others
Total
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1-2. Various type of PV cell
• Sun shine spectrum and PV
Amorphous Silicon
Crystalline Silicon
Irradiance ( W/m)
Relative Spectral response
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Sun Spectrum
Wavelength (nm)
Ultra Violet
Visible light
Infra Red
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1-2. Various type of PV cell
• Production share of the world market
KyoCera
8.8%
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Others
11.7%
EU
26.3%
1,194.7MW
(2004)
SHARP
27.1%
Japan
50.3%
USA
11.6%
SANYO
5.4%
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13
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1-2. Various type of PV cell
• How to make PV’s silicon
Semiconductor
Wafer for IC
Raw Silicon
IC Chip
Refining
99.99999999 %
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Garbage,Edge,Inferior IC
(Melt again)
Under developing
(Expensive now)
PV
Refining
99.9999 %
Refining purity is lower than IC
To
Toget
getcheaper
cheapersilicon,
silicon,recycled
recycledsilicon
siliconisisused
usedfor
forPV.
PV.
Amount
of
raw
material
is
affected
by
IC
industry’s
Amount of raw material is affected by IC industry’sproduction
production
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1-2. Various type of PV cell
• Use insolation efficiently and reduce materials
Texturized surface
( like a pyramid )
Low resistance fine
patterned front electrode
Anti reflection
coating
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Slice thin wafer
Back side reflective
electrode
Reduce reflection
Polycrystalline ingot
Poly Si wafer
Wire saw
fine wire saw
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1-2. Various type of PV cell
• Hierarchy of PV
Cell
Volt
Ampere
Watt
Size
0.5V
5-6A
2-3W
about 10cm
5-6A
100-200W about 1m
Module 20-30V
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Array
200-300V 50A-200A 10-50kW
Array
about 30m
10 - 50 kW
Module,Panel
100 - 200 W
Cell
2–3W
6x9=54 (cells)
100-300 (modules)
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1-2. Various type of PV cell
• Roughly size of PV Power Station.
In this conference room, how much PV panel we can install?
20m(65feet)
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2
11kw
kwPV
PVneed
need10
10m
m2
Conference
Room
(We are now)
Please
remember
Our room has about 200 m2
We can install about
20 kW PV in this room
10m(32feet)
30
15
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1-3. Installation example
• Roof top style ( Residence )
•Main grid connected
•AC supply
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•No battery
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1-3. Installation example
• Roof top style ( School , Community-center building)
•Main grid connected
•AC supply
•With battery for emergency
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1-3. Installation example
• Roof top style ( Off grid power supply )
•No Grid connection
•AC supply
•With battery
Relay station on top of mountain
Advertising sign beside highway
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1-3. Installation example
• Roof top style ( Mountain lodge)
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Inverter and controller
1.2kW system
•No Grid connection
•AC supply
•With battery
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1-3. Installation example
• Stationary style
•Independent small Grid connection
•AC supply
•With battery
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
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2-1-3. Example
• Electrification of a village (in Thailand)
• Small Grid connection
(3 villages grid)
• AC supply
• With battery
The system supplies alternating current
electricity 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
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1-3. Installation example
• Solar Home System (SHS)
•No Grid connection
•DC supply
•With battery
Solar array
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Solar array
Solar array
Controller
Light
Solar array
Storage battery
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37
1-4. Basic Characteristic
• I / V curve and P-Max control
P
A
V
(A)
N
Ipmax
Current(I)
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P1
I/V curve
• To obtain maximum power, current
control (or voltage control) is very
important.
• “Power conditioner” (mentioned
later) will adjusts to be most suitable
PMAX voltage and current automatically.
PP-Max
Maxcontrol
control
IxV=W
Power curve
P2
(V)
Voltage(V)
Vpmax
38
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1-4. Basic Characteristic
• Estimate current and voltage by I / V curve
A
P
R = 0.05(Ω)
(A)
N
10
R = 0.05(Ω)
V
R =
I
8
Current(I)
Then power is 10x0.5=5 W
PV character
12
e7 / PPA Workshop on Renewable Energies
If the load has 0.05 ohm resistance,
Circuit current is 10 A
Voltage is 0.5 V
6
si
Re
4
nc
sta
ec
ter
ac
r
ha
2
0
0
0.1
0.2
0.3
0.4
Voltage(V)
0.5
(V)
0.6
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1-4. Basic Characteristic
• I / V curve vs. Insolation intensity
•Current is affected largely by change
of insolation intensity.
P
5A
•Partially shaded serial cell will
produce current mismatch.
Bypass Diode
Mismatch
1A
High intensity insolation
N
5A
Current(I)
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(A)
N
P
P
Low intensity insolation
5A
1A
Bypass
Diode
N
P
IxV=W
1A
(V)
4A
N
40
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1-4. Basic Characteristic
• Temperature and efficiency
•When module temperature rises up, efficiency decreases.
•The module must be cooled by natural ventilation, etc.
Efficiency (%)
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14
Crystalline cell
2%
down
12
10
0.4 –
)
Amorphous cell
0.25 (%/deg)
8
6
4
0.5 (
%/de
g
Summer time
on roof top
(65C)
Typical
(25C)
0
10
20 30 40 50 60 70
Module Temperature (deg.C)
80
90 100
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1-5. Case study
• Maximum power control
Q : Calculate loaded power to resistance.
( I / V curve is next page)
(Work)
P
R = 0.02(Ω)
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N
P
R = 0.05(Ω)
N
P
R = 0.10(Ω)
N
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1-5. Case study
• Maximum power control
R =
(A)
V
I
R = 0.05(Ω)
12
Current(I)
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10
8
6
4
2
0
0
0.1
0.2
0.3
0.4
Voltage(V)
0.5
(V)
0.6
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43
1-5. Case study
• Maximum power control
R =
R = 0.02(Ω)
(A)
P = 0.50 ×10.0 = 5.00(W )
Current(I)
10
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R = 0.05(Ω)
P = 0.23×11.2 = 2.58(W )
12
V
I
8
R = 0.10(Ω)
6
P = 0.58 × 5.7 = 3.31(W )
4
2
0
0
0.1
0.2
0.3
0.4
Voltage(V)
0.5
0.6
(V)
44
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1-5. Case study
• Maximum power control
Q : Calculate loaded power to the resistance.
( I / V curve is next page)
P
R = 0.02(Ω)
P = 0 .23 × 11 .2 = 2 .58 (W )
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N
Maximum
P
R = 0.05(Ω)
P = 0 .50 × 10 .0 = 5 .00 (W )
R = 0.10(Ω)
P = 0 .58 × 5 .7 = 3 .31(W )
N
P
N
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45
1-5. Case study
• Bypass Diode
Q : Calculate maximum power of each system.
a : No bypass diode.
b : With bypass diode.
( I / V curve is next page)
System “a”
System “b”
P
P
N
P
N
P
N
N
(Work)
46
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1-5. Case study
• Bypass Diode
(A)
P1max (0.5V,10A)
High insolation intensity
12
Current(I)
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10
P2max (0.5V,4A)
8
6
Low insolation intensity
PXmax (0.6V,3A)
4
2
0
0
0.1
0.2
0.3
0.4
Voltage(V)
0.5
(V)
0.6
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47
1-5. Case study
• Bypass Diode
3.6 W
For system “a”
(A)
P1max (0.5V,10A)
High insolation intensity
12
Current(I)
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10
P2max (0.5V,4A)
8
6
Low insolation intensity
PXmax (0.6V,3A)
4
Pa1 = 0.6 × 3 = 1.8(W )
Pa 2 = 0.6 × 3 = 1.8(W )
2
0
0
0.1
0.2
0.3
0.4
Voltage(V)
0.5
0.6
(V)
48
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1-5. Case study
• Bypass Diode
7.0 W
For system “b”
(A)
P1max (0.5V,10A)
High insolation intensity
12
Current(I)
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10
P2max (0.5V,4A)
Pb1 = 0.5 × 10 = 5.0(W )
8
6
Low insolation intensity
PXmax (0.6V,3A)
4
Pb2 = 0.5 × 4 = 2.0(W )
2
0
0
0.1
0.2
0.3
0.4
Voltage(V)
0.5
(V)
0.6
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49
1-5. Case study
• Bypass Diode
Q : Calculate maximum power of each system.
a : No bypass diode.
b : With bypass diode.
( I / V curve is next page)
System “b”
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System “a”
P
3A
P
10A
1.8 W
5.0 W
N
P
N
P
1.8 W
N
Total = 3.6 W
4A
6A 2.0 W
N
Total = 7.0 W
50
25
22-Nov-05 (17:52)
1-5. Case study
• Temperature vs. Efficiency
Q: Suppose there is a 50 kW Crystalline PV system. (Work)
If surface temperature rises to 65ºC, what is the system
capacity?
Efficiency (%)
e7 / PPA Workshop on Renewable Energies
14
Crystalline cell
2%
down
12
0.4 –
0.5 (
%/d
eg)
10
Amorphous cell
0.25 (%/deg)
8
6
Summer time
on roof top
(65C)
Typical
(25C)
4
0
10
20
30
40
50
60
70
80
90
100
Module Temperature (deg.C)
22-Nov-05 (17:52)
51
1-5. Case study
• Temperature vs. Efficiency
Q: Suppose there is a 50 kW Crystalline PV system.
If surface temperature rises to 65ºC, what is the system
capacity?
14
Efficiency (%)
e7 / PPA Workshop on Renewable Energies
13
2%
down
12
50 ×
Crystalline cell
0.4 –
0.5 (
%/d
eg)
11
10
11
= 42 .3( kW )
13
Approx. 15% down
Amorphous cell
0.25 (%/deg)
8
6
Summer time
on roof top
(65C)
Typical
(25C)
4
0
10
20
30
40
50
60
70
80
90
100
Module Temperature (deg.C)
52
26