1. Photovoltaic By-Pass Diodes (LTspice IV)
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2. All Rights Reserved Copyright (C) Bee Technologies Corporation 2011
Contents
Solar Module Model and Specification
Bypass Diode Model
Modules without the Bypass Diodes
Modules with the Bypass Diodes
Solar Module Field with the Bypass Diodes
Library Files and Symbol Files Location
Simulation Index
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3. 1. Solar Module Model and Specification
No. SC75-RT-A
Maximum power(Pmax)
75(W)
Voltage at Pmax(Vmp)
40.5(V)
Current at Pmax(Imp)
1.85(A)
Short-circuit current(Isc)
2.20(A)
Open-circuit voltage(Voc)
55.5(V)
Parameter, SOL is added as normalized incident radiation, where SOL=1 for AM1.5 conditions
Fig.1 A single solar module part number SC75-RT-A
The specification of Showa Shell's solar module SC75-RT-A are shown in the table.
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011

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2. Bypass Diode Model
IF-VF Characteristic:
.model Dbypass D
+ IS=10.134E-6 N= RS=12.648E-3
Bypass Diodes
Fig.2 A bypass diode is connected to the solar module.
Fig.3 Shottky diode I-V characteristics.
Shottky diode is used as a bypass. I-V characteristic of the diode is shown in the graph.
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5. 3. Modules without the Bypass Diodes
Simulation Circuit
Simulation Result
Current is limited by an inactive module
Current
SOL=1
SOL=0.2 (under shade)
Power
Under shade, incident radiation drops to 20%
SOL=1
SOL=0.2 (under shade)
Simulate 3 solar modules that are connected in series without bypass diode when one module is in shade. the simulation result shows how the power and current are lowered.
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6. 4. Modules with the Bypass Diodes
Simulation Circuit
Simulation Result
Current flow past an inactive module
Current
SOL=1
SOL=0.2 (under shade)
Power
Under shade, incident radiation drops to 20%
SOL=1
SOL=0.2 (under shade)
With the bypass diode when one module is in shade. the simulation result shows that the output of the active modules can flow past an inactive module.
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7. 5. Solar Module Field with the Bypass Diodes
Activated Bypass Diode
Current Flow
Under shade, incident radiation drops to 20%
Simulate solar field that’s built from 30 solar modules in series with bypass diode across group of 10 modules when one group is in shade.
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8. 5. Solar Module Field with the Bypass Diodes
Current
SOL=1
SOL=0.2 (under shade)
Power
SOL=1
SOL=0.2 (under shade)
The graphs show I-V and P-V with bypass diodes across groups of 10 modules.
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011

9. Library Files and Symbol Files Location
…\Photovoltaic By-Pass Diodes
Copy/Paste into
C:\Program Files\LTC\LTspiceIV\lib\sub
Copy/Paste into
C:\Program Files\LTC\LTspiceIV\lib\sym
Copy the library files (.lib) from the folder …\Photovoltaic By-Pass Diodes\.sub\, then paste into the folder C:\Program Files\LTC\LTspiceIV\lib\sub
Copy the symbol files(.asy) from the folder …\Photovoltaic By-Pass Diodes\.asy\, then paste into the folder C:\Program Files\LTC\LTspiceIV\lib\sym
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011

10. All Rights Reserved Copyright (C) Bee Technologies Corporation 2011
Simulation Index
Simulations
Folder name
Bypass Diode Model
Modules without the Bypass Diodes
Modules with the Bypass Diodes
Solar Module Field with the Bypass Diodes
...\Simulation\Bypass-Diode
...\Simulation\Case1\Type-A
...\Simulation\Case1\Type-B
...\Simulation\Case2
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011