Post on 20-Feb-2021
Realize Full Potential of
Bifacial PERC Technology
Hongbin Fang
Director of Product and Technology
Amsterdam, Netherlands
September 16, 2019
2019201820172016
2
Bifacial PERC at LONGi
2016Started R&D on Bifacial
2017 December1st Bifacial project (20MW) COD
2018 Q41st overseas Bifacial project
2017 SNECLaunch HiMO2 Bifacial Module
3
Bifacial PERC: another way to improve efficiency
Improve Cell Efficiency
4
Control Power Degradation
5
• LeTID is generally believed to be related to metal impurity and H defect in the wafer substrate
• LONGi Solar, as integrated ingot/wafer/cell/module manufacturer, has tackled this issue from multiple directions: improve wafer quality and optimize cell processes
Module LeTID performance
3rd party LeTID testing results at 75C
6
Cell w/ M6 wafer (166mm)
✓ Upgraded Bifacial PERC technology
✓ Efficiency up to 22.5%
✓ 6 busbars
✓ Better light receptionFront power up to 440W
Module
Hi-MO4: Bifacial Module with Power up to 440W
Jan.2019
Mono/Bifacial PERC Efficiency Record
Module Efficiency
20.83%Cell Efficiency
24.06%
7
Apr. 2019 Nov. 2018
72-Cell Module Power
450.4W
Optimize Bifacial Module Design
JBox outside active cell area
◼ Minimize backside shading from JBox
Higher Loading Performance
◼ Static Loading can reach 5400Pa
◼ Higher protection
No C surface on short edge frame
◼ Minimize backside shading from
frame
◼ Bifacial modules with frame can reduce module breakage rate during transportation and installation
◼ Bifacial modules with frame can save labor cost and are compatible with tracker system
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LONGi Manufacturing Capacity (GW)
28
36
50
65
8.8
16
2530
2018 2019 2020 2021
Ingot/wafer Module
Bifacial Technology is not only about Module
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Source: NREL
InverterStorage
Racking/tracker
System integration plays a key role in improving bifacial gain
Backside Energy Yield: Albedo
Bifacial gain improves with increasing ground Albedo
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GrasslandAlbedo:0.26
New SnowAlbedo:0.82
Dry asphaltAlbedo:0.09-0.15
Dry SandAlbedo:0.2-0.35
CementAlbedo:0.25-0.35
Red TilesAlbedo:0.33
Source: PVSyst
Backside Energy Yield: Albedo and Height
⚫ Bifacial module backside energy
yield improves with increasing
Albedo (background reflectivity).
Selecting site with more reflective
background can improve overall
system energy yield
⚫ Increasing module height
improves backside energy yield,
as well as backside irradiance
uniformity
⚫ Module height (clearance from
ground) of 1m and above is
recommendedIrradiance at backside - Clearance 8 cm Irradiance at backside - Clearance 108 cm
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Simulation Result of Optical Loss with
Rack Clearance and Thickness
Field Test Result and Simulation
Result Comparison
Bifacial System Design: Shading Impact
⚫ Based on the simulation result, increasing the rack clearance or decreasing the rack thickness can reduce optical loss
⚫ Field measurement matches simulation result well
⚫ If backside rack shading is unavoidable, setting the rack clearance larger than 40mm is highly recommended
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Energy yield gain at 1m racking height:
TPO (12.34%) > Concrete (9.82%) > Grass (6.84%)Energy yield gain (TPO floor):
2m (22.97%) > 1.5m (18.94%) > 1m (12.34%)
Bifacial PERC Module
Field Monitoring Data
Energy yield comparison Bifacial vs. mono PERC
Sept. Oct. Nov. Dec. Jan. Feb. Total
Grass Concrete TPO
En
erg
y g
ain
pe
r w
att
Energ
y gain
per
watt
Sept. Oct. Nov. Dec. Jan. Feb. Total
1m 1.5m 2m
Energy yield comparison Bifacial vs. mono PERC
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Taizhou test site (N32.5°/ E119.9°)
0%
2%
4%
6%
8%
10%
12%
0
3
6
9
12
15
18
BiFi
Gai
n (%
)
Spec
Yie
ld b
y Bi
n (k
Wh/
kWp)
Dark
Bin BiFi Spec Yld (kWh/kW) Bin Mono Spec Yld (kWh/kW) Bin Spec Yld BiFi Gain
3%
6%
9%
12%
15%
18%
21%
0
3
6
9
12
15
18
4/27/2019 4/28/2019 4/29/2019 4/30/2019 5/1/2019 5/2/2019 5/3/2019 5/4/2019 5/5/2019 5/6/2019 5/7/2019
BiFi
Gai
n (%
)
Spec
Yie
ld b
y Bi
n (k
Wh/
kWp)
White
Bin BiFi Spec Yld (kWh/kW) Bin Mono Spec Yld (kWh/kW) Bin Spec Yld BiFi Gain
15
Bifacial PERC Module
Field Monitoring Data
⚫ 5 modules fixed tilt system established and monitored by 3rd party lab RETC/B&V in California (N37.5, W122.0)
⚫ Bifacial gain correlates to surface Albedo: − White/Asphalt/Dark rooftop, Albedo 60.5%/22.9%/7.6%− White/Asphalt/Dark rooftop, bifacial gain15.4%/10.8%/4.2%
Dark: +4.2%
Site Fremont, CA
Sample Size 5 Mono + 5 BiFi
Mounting Type Fixed Tilt
Surface Type
White: Albedo 60.5%
Asphalt: Albedo 22.9%
Dark: Albedo 7.6%
Data
Resolution
Module-level (via DC
Optimizer)
0%
3%
6%
9%
12%
15%
18%
0
3
6
9
12
15
18
BiFi
Gai
n (%
)
Spec
Yie
ld b
y Bi
n (k
Wh/
kWp)
Asphalt
Bin BiFi Spec Yld (kWh/kW) Bin Mono Spec Yld (kWh/kW) Bin Spec Yld BiFi Gain
Asphalt: +10.8%
White: +15.4%
0%
2%
4%
6%
8%
10%
12%
14%
0
2
4
6
8
10
12
14
10
/23
/20
18
10/2
6/2
018
10
/29
/20
18
11
/1/2
01
8
11
/4/2
01
8
11
/7/2
01
8
11
/10
/20
18
11
/13
/20
18
11
/16
/20
18
11
/19
/20
18
12
/1/2
01
8
12
/4/2
01
8
12
/7/2
01
8
12
/10
/20
18
12
/13
/20
18
12/1
6/2
018
12
/19
/20
18
12
/22
/20
18
12
/25
/20
18
12
/28
/20
18
12/3
1/2
018
1/3
/20
19
1/6
/20
19
1/9
/20
19
1/1
2/2
01
9
1/1
5/2
01
9
1/1
8/2
01
9
1/2
1/2
01
9
1/2
4/2
01
9
1/2
7/2
01
9
1/3
0/2
01
9
2/2
/20
19
2/5
/20
19
2/8
/20
19
2/1
1/2
019
2/1
4/2
01
9
2/1
7/2
01
9
2/2
0/2
01
9
2/2
3/2
01
9
2/2
6/2
019
3/1
/20
19
3/4
/20
19
3/7
/20
19
3/1
0/2
01
9
3/1
3/2
01
9
3/1
6/2
01
9
3/1
9/2
01
9
3/2
2/2
01
9
3/2
5/2
01
9
3/2
8/2
01
9
3/3
1/2
01
9
4/3
/20
19
4/6
/20
19
4/9
/20
19
4/1
2/2
01
9
4/1
5/2
01
9
4/1
8/2
01
9
4/2
1/2
01
9
4/2
4/2
019
4/2
7/2
01
9
4/3
0/2
01
9
BiF
i G
ain
(%
)
Spe
c Y
ield
by
Bin
(kW
h/k
Wp
)
Spec Yield (by Bin) Comparison
Bin BiFi Spec Yld (kWh/kW) Bin Mono Spec Yld (kWh/kW) Bin Spec Yld BiFi Gain
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Bifacial PERC Module
Field Monitoring Data
Site Pahrump, NV
Sample Size 8 Mono + 8 BiFi
Mounting Type Fixed Tilt, 1m clearance
Surface TypeWhite Gravel
(Albedo 34.5%)
Data
ResolutionString-level via Inverter
⚫ 8 module fixed tilt system established and monitored by 3rd party lab RETC/B&V in Nevada (N36.2, W116.0)
⚫ Bifacial gain of 9.8% has been demonstrated with 6 months data acquisition
+9.8%
0.0%
2.0%
4.0%
6.0%
8.0%
10.0%
12.0%
14.0%
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
BiF
i Ga
in/S
hd
Alb
ed
o R
ati
o (%
)
Spe
c Y
ield
by
Pm
ax
(kW
h/k
Wp
)
BiFi spec yield (kWh/kWp) Mono PERC spec yield (kWh/kWp) BiFi gain (%)
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Bifacial PERC Module
Field Monitoring Data
⚫ 6 modules on SAT system established and monitored by 3rd party lab RETC/B&V in California (N37.7, W121.7)
⚫ Bifacial gain of 8.0% has been demonstrated with 3 months data acquisition
+8.0%
Site Livermore, CA
Sample Size 6 Mono + 6 BiFi
Mounting Type Single-Axis Tracker
Surface Type Gravel
Data Resolution Module-level (via DC
Optimizer)
⚫ Bifacial PERC project (336kw on single axis tracker) in Kubuchi, Inner Mongolia (N45.36°/E118.36°), China
⚫ 18-month energy yield by Bifacial module + tracker is 26.6% higher than Multi module/fixed tilt and 16.2% higher than Multi/tracker
+16.2%
Bifacial PERC Module
Field Monitoring Data
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▪ Bifacial technology has been widely deployed globally− Bifacial PERC technology effectively achieved advanced n-type efficiency at p-type
cost, offering competitive system economics
− Significant backside energy yield has been demonstrated through field data collection
▪ To realize full potential of bifacial PERC technology− Cell efficiency and module power output will continue to improve
− Module reliability and power degradation need to be controlled well
− Continuous capacity expansion will ensure sufficient bifacial module supply
− System integration plays a key role in improving bifacial gain
Summary