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Les défis et les solutions pour une mesure précise de panneaux bifaciales (Challenges and solutions for an accurate power rating of bifacial modules)Rajesh Ambigapathy; March 2017

BiFacial PV Panels an upcoming technology:Migros Schoenbuehl a MB Project

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Bi-facial HJT

Smartwire

Standard

mono-facial

modules

How to standardize the of performance gain of Bi-Facial panels?

Bi-Facial vs Mono-Facial PV PanelUnderstanding the gains

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100%

15 - 25 %

4

31

0W

+

32

0W

bif

acia

l

1. What values are reported?

2. How is the simulator calibrated?

3. How are these two BiFi panels measured?

Rating Bi-facial panelsComparing apples to apples

Measurement of Mono-facial is standardized according to IEC 60904-1

How to standardize BiFi is the job of WG2.

Particularities of BiFi:

A reproducible method for Reference Institutes to measure Golden Panels

Calibration and measurements in production of BiFi panels to highlight gain

IEC 60904-1-2 Standardizing of BiFi measurements

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Measurement Device Output

Lab

ora

tory Bifaciality measurement

Golden reference

Bifaciality coefficients

Bifacial gain determination Bifaciality gain factor

Pro

du

cti

on

STC measurement Production batchPmaxSTC

PmaxBiFi (Calculated)

IEC BiFi standard method at a glance

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Calculate:

𝜑𝐼𝑠𝑐 =𝐼𝑠𝑐𝑟𝐼𝑠𝑐𝑓

𝜑𝑉𝑜𝑐 =𝑉𝑜𝑐𝑟𝑉𝑜𝑐𝑓

𝜑𝑃𝑚𝑎𝑥 =𝑃𝑚𝑎𝑥𝑟𝑃𝑚𝑎𝑥𝑓

Extract Bifaciality coefficient:

𝜑 = 𝑴𝒊𝒏(𝜑𝐼𝑠𝑐 , 𝜑𝑃𝑚𝑎𝑥)

Used for Production calibration:

𝑰𝒔𝒄𝑹𝒆𝒇 𝒇𝒐𝒓 𝒄𝒂𝒍𝒊𝒃𝒓𝒂𝒕𝒊𝒐𝒏 = 𝑰𝒔𝒄𝒇

Step 1: Bifaciality measurement

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Measure:

𝑰𝒔𝒄𝒇

𝑉𝑜𝑐𝑓

𝑃𝑚𝑎𝑥𝑓

Measure:

𝐼𝑠𝑐𝑟

𝑉𝑜𝑐𝑟

𝑃𝑚𝑎𝑥𝑟

Measure panel performance with:

The equivalent of 1 Sun on the front 0.1 sun on the back side

The equivalent of 1 Sun on the front 0.2 sun on the back side

This can be done indoors use bifaciality coefficient to determine the right illumination level

Report this information on the test report of the Golden Panel

Step 2: Bifacial gain determinationMeasurements with overexposure

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Measuring panels in productionA simple yet reliable approach

1. Use Golden to calibrate simulator (as usual)

2. Measure Front side at STC

Report:

• PMax @ STC

• PMax BiFi10 (Calculated using Pmax @ STC)

• Pmax BiFi 20 (Calculated Pmax @ STC)

IEC 60904-2 BiFi project status

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IEC new standard

project stages

Outputs Duration

Preliminary stage

Proposal stage

Preparatory stage

Committee stage A Committee Draft (CD) for

comments was submitted to the

National Committees in March

2017.

2-4 months available

for national bodies to

comment

Enquiry stage Committee Draft for vote (CDV) 3-months voting

period

Approval stage Final Draft International Standard

(FDIS) (if negative votes at CDV)

(2-months voting

period if required)

Publication stage 1.5 months

A new IEC standard to assess performance of bifacial devices and to value the bifacial gain.

This standard is in a advanced stage

The new standard does not require new measurement equipment in PV productions.

Conclusion

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Thank you for your attention

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BiFi-compatible module

tester

Meyer Burger’s HJT bifacial

modules with busbarless

cells on CSEM’s facade