RESULTS FROM FLASH TESTING AT MULTIPLE IRRADIANCES AND

TEMPERATURES ACROSS FIVE PHOTOVOLTAIC TESTING LABS

3rd PV Performance Modeling Workshop

May 5, 2014, Santa Clara, CA

Junaid H. Fatehi1, Cherif Kedir2, Charles Tumengko3, Nick Riedel4, John L. R. Watts5

1Yingli Green Energy Americas, San Francisco, CA 2Renewable Energy Test Center, Fremont, CA

3Intertek Testing Services, Lake Forest, CA 4CFV Solar Test Laboratory, Albuquerque, NM

5PV Evolution Labs, Berkeley, CA

Published by Sandia National Laboratories with the permission of the authors.

Background

• For reliable system energy yield modeling, it is important to

characterize the dependence of PV module performance on

irradiance and operating temperature, for conversion into module

performance models used in energy simulation

• This study was coordinated by Yingli Green Energy Americas and it

investigates the contribution of data source in the measurement and

understanding of PV module behavior

• Three light-stabilized multicrystalline silicon PV modules from Yingli

Solar were sent to five testing labs for round robin characterization

Participating Labs • CFV Solar Test Laboratory

– Albuquerque, NM

• Intertek Testing Services – Lake Forest, CA

• Renewable Energy Test Center – Fremont, CA

• PV Evolution Labs – Berkeley, CA

• Yingli Americas PV Testing Lab – South San Francisco, CA

All labs are assigned a random number for anonymous reporting.

Testing Scope

• Multiple Irradiance Testing – Testing between 100 W/m2 and 1,000 W/m2

– Minimum testing interval of 100 W/m2

– Fixed testing temperature of 25 oC

• Temperature Coefficient Testing – Testing between 25 oC and 65 oC

– Maximum testing interval of 5 oC

– Fixed testing irradiance of 1,000 W/m2

Testing Notes

• All five participating labs:

– Conducted electroluminescence imaging to

screen for transportation damage (none reported)

– Conducted temperature coefficient testing indoors

– Calibrated with a module tested at Fraunhofer

ISE and traceable to PTB

Standard Test Conditions 1,000 W/m2, 25 oC, AM 1.5g

Module S/N: 124804060126

Lab Isc (A) Voc (V) Imp (A) Vmp (V) Pmp (W)

1 8.785 45.69 8.281 36.53 302.5

2 8.756 45.60 8.211 36.43 299.1

3 8.826 45.55 8.256 36.41 300.6

4 8.799 45.60 8.264 36.60 302.5

5 8.874 45.59 8.300 36.77 305.1

Lab Isc Voc Imp Vmp Pmp

1 -0.26 % 0.18 % 0.22 % -0.05 % 0.18 %

2 -0.59 % -0.01 % -0.63 % -0.33 % -0.96 %

3 0.21 % -0.12 % -0.08 % -0.37 % -0.45 %

4 -0.10 % -0.01 % 0.02 % 0.15 % 0.18 %

5 0.75 % -0.04 % 0.45 % 0.60 % 1.05 %

Test Results:

Difference from the Mean:

Module S/N: 124804060149

Lab Isc (A) Voc (V) Imp (A) Vmp (V) Pmp (W)

1 8.768 45.67 8.272 36.55 302.3

2 8.732 45.56 8.185 36.51 298.9

3 8.788 45.59 8.224 36.62 301.1

4 8.753 45.61 8.245 36.69 302.5

5 8.860 45.61 8.285 36.86 305.4

Lab Isc Voc Imp Vmp Pmp

1 -0.14 % 0.13 % 0.36 % -0.26 % 0.10 %

2 -0.55 % -0.10 % -0.69 % -0.36 % -1.05 %

3 0.09 % -0.04 % -0.23 % -0.07 % -0.30 %

4 -0.31 % 0.00 % 0.04 % 0.11 % 0.15 %

5 0.91 % 0.01 % 0.52 % 0.58 % 1.10 %

Test Results:

Difference from the Mean:

Module S/N: 124804060310

Lab Isc (A) Voc (V) Imp (A) Vmp (V) Pmp (W)

1 8.741 45.62 8.220 36.51 300.1

2 8.718 45.50 8.144 36.42 296.6

3 8.725 45.50 8.158 36.61 298.6

4 8.740 45.49 8.204 36.56 299.9

5 8.858 45.51 8.232 36.77 302.7

Lab Isc Voc Imp Vmp Pmp

1 -0.18 % 0.22 % 0.34 % -0.17 % 0.17 %

2 -0.44 % -0.05 % -0.58 % -0.42 % -1.00 %

3 -0.36 % -0.06 % -0.41 % 0.09 % -0.32 %

4 -0.19 % -0.07 % 0.16 % -0.04 % 0.11 %

5 1.16 % -0.04 % 0.49 % 0.55 % 1.04 %

Test Results:

Difference from the Mean:

Multiple Irradiance Testing 25 oC, AM 1.5g

Relative Efficiency Metrics

• Relative Efficiency

– 𝐸𝑓𝑓𝑅𝑒𝑙𝐺=

𝑃𝑚𝑝𝐺∗1000 𝑊/𝑚2

𝐺

𝑃𝑚𝑝1000− 1

• Self-Referenced Relative Efficiency

– 𝐸𝑓𝑓𝑆𝑒𝑙𝑓_𝑅𝑒𝑙𝐺=

𝑃𝑚𝑝𝐺∗𝐼𝑠𝑐1000

𝐼𝑠𝑐𝐺

𝑃𝑚𝑝1000− 1

Absolute Efficiency Metrics

• Absolute Efficiency

– 𝐸𝑓𝑓𝐴𝑏𝑠𝐺=

𝑃𝑚𝑝𝐺

𝐴𝑟𝑒𝑎 ∗𝐺

• Self-Referenced Absolute Efficiency

– 𝐸𝑓𝑓𝑆𝑒𝑙𝑓_𝐴𝑏𝑠𝐺=

𝑃𝑚𝑝𝐺

𝐴𝑟𝑒𝑎 ∗𝐼𝑠𝑐𝐺

𝐼𝑠𝑐1000∗1000 𝑊/𝑚2

Module S/N: 124804060126

100 200 300 400 500 600 700 800 900 1000-8

-7

-6

-5

-4

-3

-2

-1

0

1

Relative Efficiency

Irradiance (W/m2)

Ch

an

ge

in

Eff

icie

ncy (

%)

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

100 200 300 400 500 600 700 800 900 1000-8

-7

-6

-5

-4

-3

-2

-1

0

1

Self-Referenced Relative Efficiency

Irradiance (W/m2)

Ch

an

ge

in

Eff

icie

ncy (

%)

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

100 200 300 400 500 600 700 800 900 100014.2

14.4

14.6

14.8

15.0

15.2

15.4

15.6

15.8

Absolute Efficiency

Irradiance (W/m2)

Eff

icie

ncy (

%)

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

100 200 300 400 500 600 700 800 900 100014.2

14.4

14.6

14.8

15.0

15.2

15.4

15.6

15.8

Self-Referenced Absolute Efficiency

Irradiance (W/m2)

Eff

icie

ncy (

%)

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

Module S/N: 124804060149

100 200 300 400 500 600 700 800 900 1000-8

-7

-6

-5

-4

-3

-2

-1

0

1

Relative Efficiency

Irradiance (W/m2)

Ch

an

ge

in

Eff

icie

ncy (

%)

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

100 200 300 400 500 600 700 800 900 1000-8

-7

-6

-5

-4

-3

-2

-1

0

1

Self-Referenced Relative Efficiency

Irradiance (W/m2)

Ch

an

ge

in

Eff

icie

ncy (

%)

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

100 200 300 400 500 600 700 800 900 100014.2

14.4

14.6

14.8

15.0

15.2

15.4

15.6

15.8

Absolute Efficiency

Irradiance (W/m2)

Eff

icie

ncy (

%)

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

100 200 300 400 500 600 700 800 900 100014.2

14.4

14.6

14.8

15.0

15.2

15.4

15.6

15.8

Self-Referenced Absolute Efficiency

Irradiance (W/m2)

Eff

icie

ncy (

%)

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

Module S/N: 124804060310

100 200 300 400 500 600 700 800 900 1000-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

Relative Efficiency

Irradiance (W/m2)

Ch

an

ge

in

Eff

icie

ncy (

%)

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

100 200 300 400 500 600 700 800 900 1000-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

Self-Referenced Relative Efficiency

Irradiance (W/m2)

Ch

an

ge

in

Eff

icie

ncy (

%)

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

100 200 300 400 500 600 700 800 900 100014.0

14.2

14.4

14.6

14.8

15.0

15.2

15.4

15.6

15.8

Absolute Efficiency

Irradiance (W/m2)

Eff

icie

ncy (

%)

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

100 200 300 400 500 600 700 800 900 100014.0

14.2

14.4

14.6

14.8

15.0

15.2

15.4

15.6

15.8

Self-Referenced Absolute Efficiency

Irradiance (W/m2)

Eff

icie

ncy (

%)

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

Temperature Coefficient Testing 1,000 W/m2, AM 1.5g

Short Circuit Current Temperature Coefficient

Lab 1 Lab 2 Lab 3 Lab 4 Lab 50.045

0.050

0.055

0.060%

/

CIsc

Module S/N: 124804060126

Module S/N: 124804060149

Module S/N: 124804060310

Open Circuit Voltage Temperature Coefficient

Lab 1 Lab 2 Lab 3 Lab 4 Lab 5-0.345

-0.340

-0.335

-0.330

-0.325

-0.320

-0.315

-0.310

-0.305

% /

C

Voc

Module S/N: 124804060126

Module S/N: 124804060149

Module S/N: 124804060310

Maximum Power Temperature Coefficient

Lab 1 Lab 2 Lab 3 Lab 4 Lab 5-0.47

-0.46

-0.45

-0.44

-0.43

-0.42

-0.41

-0.40%

/

CPmp

Module S/N: 124804060126

Module S/N: 124804060149

Module S/N: 124804060310

Conclusions

• Self-referencing irradiance results in smoother efficiency curves and better relative efficiency agreement between labs

• Three out of five labs have good agreement on Voc temperature coefficients and moderate agreement on Pmp temperature coefficients

Thank You

Contact Junaid H. Fatehi at juanid.fatehi@yingliamericas.com for questions and comments.

For Discussion

* Annual energy yield estimates were performed in PVsyst for a fixed system design and using .PAN files created from each participating lab’s measurement data in accordance with “Systematic Approaches to Ensure Correct Representation of Measured Multi-Irradiance Module Performance in PV System Energy Production Forecasting Software Programs”, presented at Sandia's 2013 PV Performance Modeling Workshop by Kenneth J. Sauer and Thomas Roessler.

Deviation in estimated annual energy yield from the mean for each location.*

-0.8%

-0.6%

-0.4%

-0.2%

0.0%

0.2%

0.4%

0.6%Antofagasta, Chile Berlin, Germany Phoenix, USA Trivandrum, India

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5