Gensol has estimated Bifacial Gain varying between ~4.0-10.5% when Bifacial PV Modules are configured with Single Axis Tracker (SAT) system depending on system configuration & ground albedo. Various iterations of energy generation were simulated using PVsyst to understand the impact of design considerations and climatic factors on the Bifacial Gain of 1P x 30 Bifacial PV array with SAT system equipped over-torque tube for India & Middle East regions.

1. 1
Impacting design factors & climatic
conditions
Bifacial Gain in Asia & Middle
East Region
Solar PV Consulting
Gensol Engineering Limited
Published on 06th March 2020

2. 2
• Bifacial solar cells and modules collects light incident
on both of its surface (front & rear) including the light
reflected from the surroundings and ground. The bifacial
modules are beneficial for deployment at regions where a
space constraint exists. The advancement in research,
large scale manufacturing technologies and higher energy
output of bifacial cells & modules leads to significant
levelized cost of energy savings in comparison to
conventional mono-facial PV modules.
• Single axis tracking (SAT) is a cost-effective deployment
for large scale ground mounted PV systems receiving
good amount of solar radiation. The emergence of cost
competitive bifacial PV modules has raised the question
of additional value of bifacial modules in SAT systems.
A) Introduction
Gensol has estimated Bifacial Gain varying between ~4.0-10.5% when Bifacial PV Modules are
configured with SAT system depending on system configuration & ground albedo. Various iterations of
energy generation were simulated using PVsyst to see the impact of design considerations and climatic
factors on the bifacial gain of 1P x 30 Bifacial PV array with SAT system equipped over - torque tube for
India & Middle East regions.

3. 3
B) About Pvsyst Model
The model is used to study the bifacial gain as a function of
below factors :
1. Reflection from ground surface (Albedo)
2. Pitch between the rows of PV array
3. Height of PV mounting structure
4. Geo co-ordinates of location
PVsyst simulation software provides a simplified model which
captures the main bifacial contributions as mentioned below,
depending on the design parameters, weather parameters and
region selected.
• Direct and diffused light scattered back from the ground
• Direct and diffused light directly reaching the rear side of
the bifacial PV modules

4. 4
C) Mathematical Formula
For determining the Bifacial Gain, the mathematical formula used
as below:
Where, 𝐸 𝑏𝑖𝑓𝑎𝑐𝑖𝑎𝑙 = Energy generated by bifacial PV module
𝐸 𝑚𝑜𝑛𝑜𝑓𝑎𝑐𝑖𝑎𝑙 =Energy generated by bifacial PV module
considering rear surface inactive
𝐵𝑖𝑓𝑎𝑐𝑖𝑎𝑙 𝐺𝑎𝑖𝑛 =
𝐸 𝑏𝑖𝑓𝑎𝑐𝑖𝑎𝑙
𝐸 𝑚𝑜𝑛𝑜𝑓𝑎𝑐𝑖𝑎𝑙
− 1
Source: Soltec
Sankey’s Loss Diagram for Bifacial Module

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D) Methodology & Assumptions
i. Locations & Plant Configuration
East
Zone
West
Zone
S.No. Parameter Value
1. Plant Capacity &
Overloading
3.125 MW/4.374 MWp
40% Overloading
2. Module Make & Capacity Trina Solar – 360 Wp
3. Module Technology Bifacial (glass- to - glass)
4. Inverter Make & Capacity Sungrow – 3125 kW
5. Inverter Technology Central
6.
Orientation Plant Location Tilt(°)
a) Optimized Fixed Tilt
Bhadla 20
Mohammed bin
Rashid Al Maktoum
15
Pavagada 12
b) Horizontal Single Axis
Tracker
- 60⁰ to +60⁰
7. Azimuth (⁰) 0
8. Rear shading factor (%) 5
9. Rear mismatch factor (%) 10

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D) Methodology & Assumptions
ii. Ground Surface and Albedo
For the mentioned project configuration and locations, plant
energy generation has been analyzed by considering ground
surfaces having different albedo as follows:
iii. Pitch & Height of Mounting Structure
East
Zone
South
Zone
West
Zone
The range of pitch and height of mounting structure
considered for analyzing the performance of plant is as
follows:
*Source: i) https://www.researchgate.net/publication/242547003_Albedo
ii) https://www.researchgate.net/publication/257794750_Variation_of_albedo_to_soil_moisture_for_sand_dunes_and_biological_soil_crusts_in_arid_desert_ecosystems
S.No. Ground Surface Albedo*
1. Snow 0.85
2. White Paint 0.80
3. Dry Sand 0.45
4. Dry Soil 0.35
5. Desert 0.25
6. Green Grass 0.20
7. Dark and Wet Soil 0.15
Pitch – 5.00 to 6.00 m (Interval of 0.1 m)
Height – 1.35 to 1.95 m (Interval of 0.1 m)
Snow
Desert Green Grass
Dry Sand Dry Soil
Dark & Wet Soil

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• The solar PV plant is assumed to have horizontal single
axis trackers with regular spacing.
• Snow and white paint has been considered as
benchmark scenario.
• The rotation limit of the tracker has been considered as
- 60° to + 60°.
• The rear shading loss factor and rear mismatch loss has
been considered as 5.0% & 10.0% respectively.
iv. Assumptions
• It has been considered that no radiation scattering
occurs due to the nearby PV arrays and radiation
reaching the rear surface of module is due to scattering
by sky/atmospheric particles.
• The variation in pitch and height of module mounting
structure (MMS) has no effect on operating temperature
of module.
• Meteonorm database has been used for determination
of energy generation for all the considered combinations.
D) Methodology & Assumptions
Rear shading loss factor: It accounts for the losses that occur due to the shading of some of mechanical structures behind the module.
Rear mismatch loss: It accounts for the losses that occur due to non-uniform current being generated in modules because of non-uniform irradiance
incident on the rear side of the module.

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D) Methodology & Assumptions
Technology Selection
& Finalization Of
Plant Configuration
Sets Of Pitch, Height
Of Mounting
Structure, Ground
Albedos &
Locations Has Been
Defined
Simulation Of Pvsyst
For Predefined
Project Configuration
And Combination Of
Sets
Calculation Of
Bifacial Gain For All
Combination Of Sets
Analysis Of Results

9. 16.84%
16.03%
10.41%
8.56%
6.59%
5.56%
4.51%
14.40%
13.72%
9.04%
7.46%
5.78%
4.90%
3.99%
0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
BifacialGain(%)
Albedo
Bifacial Gain(%) Vs Albedo
Bhadla Mohammed bin Rashid Al Maktoum Pavagada
9
E) Analysis & Results
❑ IMPACT OF GROUND SURFACE ALBEDO ON BIFACIAL GAIN: The trend indicates that bifacial gain of the module with SAT
increases with increase in ground surface albedos for all the three considered locations.
Height = 1.95 m , Pitch =6.00 m
Dark&WetSoil
GreenGrass
Desert
DrySoil
Dry
Sand
WhitePaint
Snow

10. 0
100
200
300
400
500
600
700
4.8 5.0 5.2 5.4 5.6 5.8 6.0 6.2
Globalirradianceonrearside(kWh/m2)
Pitch(m)
Ground Irradiance on Rear Side Vs Pitch
10
E) Analysis & Results
❑ IMPACT OF PITCH ON BIFACIAL GAIN: The trend indicates that bifacial gain of the module with SAT increases by ~ 0.5% to 0.7%
with increase in inter row pitch by 1 m for all the considered ground surface albedos.
Height = 1.35 m , Pitch =Varying
White Paint
Dry Sand
Dry Soil
Desert
Green Grass
Dark & Wet
Soil
Snow
Parameter Location Increase in Bifacial Gain(%) Increase in Energy Generation(%)
Increase in Pitch by 1m
Bhadla 0.49% 2.09%
Mohammed bin Rashid Al Maktoum 0.73% 2.30%
Pavagada 0.62% 2.21%
0.00%
2.00%
4.00%
6.00%
8.00%
10.00%
12.00%
14.00%
16.00%
18.00%
4.8 5.0 5.2 5.4 5.6 5.8 6.0 6.2
BifacialGain(%)
Pitch(m)
Bifacial Gain Vs Pitch
Snow
White Paint
Dry Sand
Dry Soil
Desert
Green Grass
Dark & Wet
Soil

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E) Analysis & Results
❑ IMPACT OF HEIGHT ON BIFACIAL GAIN: The trend indicates that bifacial gain of the module with SAT increases by ~1.2% to
1.8% with increase in height of module mounting structure by 1m for all the considered ground surface albedo.
Pitch = 6.00 m , Height = Varying
130
250
370
490
610
730
1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2
Globalirradianceinrearside(kWh/m2)
Height(m)
Global Irradiance on Rear Side Vs Height
Snow
White Paint
Dry Sand
Dry Soil
Desert
Green Grass
Dry & Wet Soil
3%
5%
7%
9%
11%
13%
15%
17%
19%
1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2
BifacialGain(%)
Height (m)
Bifacial Gain Vs Height
Snow
White Paint
Dry Sand
Dry Soil
Desert
Green Grass
Dry & Wet Soil
Parameter Location Increase in Bifacial Gain(%) Increase in Energy Generation(%)
Increase in Height by 1 m
Bhadla 1.15% 1.09%
Mohammed bin Rashid Al Maktoum 1.82% 1.67%
Pavagada 1.52% 1.40%

12. E) Analysis & Results
❑ IMPACT OF GEO CO-ORDINATES ON BIFACIAL GAIN: The trend indicates that for the same design parameters (pitch & height)
and ground albedos considered, the bifacial gain of module with SAT increases with increase in latitude (⁰) of the plant location.
Latitude (⁰) 14.27 24.75 27.52
Ground Surface Albedo
Bifacial Gain (%)
Pavagada
Mohammed bin Rashid
Al Maktoum
Bhadla
Snow 0.85 14.40% 16.03% 16.84%
White Paint 0.8 13.72% 15.28% 16.03%
Dry Sand 0.45 9.04% 10.11% 10.41%
Dry Soil 0.35 7.46% 8.38% 8.56%
Desert 0.25 5.78% 6.49% 6.59%
Green Grass 0.2 4.90% 5.50% 5.56%
Dark and Wet Soil 0.15 3.99% 4.47% 4.51%
Increase in Latitude of location leads to increase in Bifacial Gain
13Pitch = 6.00 m , Height = 1.95 m
14.40%
16.03%
16.84%
13.72%
15.28%
16.03%
9.04%
10.11% 10.41%
7.46%
8.38% 8.56%
5.78%
6.49% 6.59%
4.90%
5.50% 5.56%
3.99%
4.47% 4.51%
3%
6%
9%
12%
15%
18%
10 12 14 16 18 20 22 24 26 28 30
BifacialGain(%)
Latitude(⁰)
Bifacial Gain Vs Latitude
Snow
White Paint
Dry Sand
Dry Soil
Desert
Green Grass
Dry & Wet Soil

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E) Analysis & Results
❑ IMPACT OF TECHNOLOGY & CONFIGURATION ON ENERGY GAIN: The trend indicates that the energy yield of the 3.125
MW/4.374 MWp plant corresponding to optimum pitch & height of mounting structure (1.50 m) is maximum for Bifacial module
with SAT configuration for all the considered locations.
Latitude: 27.52°N ,Surface: Desert
Albedo: 0.25, Pitch: i) FT – 3m, ii) SAT- 6.5m
Latitude: 14.27°N, Surface: Dry Soil
Albedo: 0.35, Pitch: i) FT – 3m, ii) SAT- 6m
Technology and Configurations:
i) Monofacial Module – Fixed Tilt (FT) & SAT
ii) Bifacial Module – Fixed Tilt (FT) & SAT
Latitude: 24.75°N, Surface: Dry Sand
Albedo: 0.45, Pitch: i) FT – 3m, ii) SAT- 6.5m

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