Realize Full Potential of Bifacial PERC...

Realize Full Potential of

Bifacial PERC Technology

Hongbin Fang

Director of Product and Technology

Amsterdam, Netherlands

September 16, 2019

2019201820172016

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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%

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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

9

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


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⚫ 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


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

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2/5

/20

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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

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4/6

/20

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4/9

/20

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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


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Site Pahrump, NV


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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⚫ 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


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%



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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

Realize Full Potential of Bifacial PERC...

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