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Albuquerque, New Mexico

PV Module Characterization Methods at CFV Solar Test Lab

Sandia 2014 PV Systems Symposium – Santa Clara, CA

Larry Pratt , Nick Riedel, and the CFV Team

Agenda – Characterization at CFV

• Intro to CFV Solar Test Lab• Indoor characterization

– Temperature coefficients– 61853-1 performance matrix

• Outdoor characterization– Temperature coefficients– Sandia modeling coefficients

• Industry areas for improvement

Joint Venture of Renowned Standards and Research Organizations

World renowned solar research lab with deep technical expertise.

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Solar innovation lab in Massachusetts with module prototyping capabilities.

Solar certification is for European and US standards. The CFV Solar Test Laboratory joins CSA and VDE certification capabilities in PV and creates a globally accepted certification service.

Scientific & Management Advisor to CFV.

PV-module research capabilities Partner for test-standards development.

Contributing extensive expertise to design and setup the module certification lab. Partner for global PV Test center alliance.

Ideal Test Conditions in Albuquerque, NM

• Highest Solar Irradiance in USA>> Altitude keeps temperatures low

• National Research Laboratories >> Sandia, Los Alamos Nat’l labs

• Universities Active in Solar>> UNM, CNM

• Existing Solar Companies>> Emcore/Suncore, Sandia, Array Technologies, Unirac, CST, Affordable Solar, Sacred Power, …

• Political Support>> NM promotes solar on all levels of government (State, County and City)

• Good Accessibility, Workforce & Living Conditions>>Albuquerque has excellent scientists, culture and nature

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h.a.l.m. Flash Solar Simulator

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• Manufactured by h.a.l.m. Electronik• Class AAA per IEC 60904-9:

• Spectral match to AM 1.5 G• Uniformity of irradiance• Temporal stability of flash• Integrated thermal chamber (25 – 65 C)• Irradiance from Xe arc lamp• 100 - 1100 W/m2

• Controlled by voltage• Three methods of lamp calibration

• PTB calibrated reference cell (HOQ and KG3)• Control module tested at ISE Fraunhofer• Outdoor reference Isc transfer

• Three quadrant capability for DIV• I-V measurements taken with hysteresis

• Sections used if needed

h.a.l.m. indoor I-V measurement system

PTB calibrated low-uncertainty reference cell

Measurement uncertainty in IV at STC for silicon

• Absolute uncertainty calculated from an algorithm developed at Fraunhofer ISE, driven by reference cell calibration, non-uniformity, and spectral mismatch .– The uncertainty is consistent with the range of values reported in the 2005

module RR sponsored by NREL, most of which was due to the Isc (read “reference cell”)

– The authors conclude that absolute uncertainty cannot be less than +/- 3%

• Relative uncertainty is calculated from the moving range estimates of the standard deviation from two check modules that are measured daily.

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Parameter Absolute [%] Relative [%]

Pmp +/- 2.8 +/- 0.40Isc +/- 2.3 +/- 0.20Imp +/- 2.3 +/- 0.25Voc +/- 0.6 +/- 0.20Vmp +/- 0.7 +/- 0.25

Indoor Temperature Coefficient Testing

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• Determined per IEC 61215/61646 §10.4• Four RTDs place on backsheet • Module heated from 25 to 65° C• I-V measurements taken every 2°C

• Considerations:• Reference cell temperature

• Remains at 25-28°C• Temperature dwell time before measurement

• 1.5 to 2 minutes• Module temperature uniformity

• < 1.2° C with help of laminar air flow• The system is also capable of taking I-V while

cooling the module from 65 to 25° C• Heating method can be performed faster• Repeatability of +/- 0.01%/ C for Pmp

• Including effects of cool down and extended dwell times

Indoor IEC 61853-1 Performance Testing

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• A given temperature is targeted and then multi-irradiance measurements are taken.

• Irradiance is changed with lamp voltage.• A supplemental thermal chamber must be used

for temperatures outside of 25-65 ° C.• Sections measurements and hysteresis must

be adjusted accordingly.• Our partner CSE Fraunhofer creates .PAN files

based on these performance data.• The IEC spectral match rating changes

with irradiance.• Class A for all irrad. 400-800 nm• Class B/C > 800nm and < 400 W/m2

• Lower irradiances (ie voltages) shifts intensity towards λ > 700 nm.

• Spectrum shifts to IR by fractions of a percent as lamp ages.

Flasher Upgrade for Efficient 61853-1 Testing

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• ND filters to preserve spectrum below 600 W/m2

• Improved thermal capacity for testing 15-75°C

• Installed by Q4 2014 or sooner

Thermogenerator

Curve Tracer Capacitor Bank

PV DUT

Xe Arc

Outdoor Temperature Coefficients

• CFV follows the procedures established at SNL – work instructions will be available later this year– Shade module, cool to near ambient, insulate backside, set up curve tracer, uncover, sweep curves while

module heats in the sun, regression analysis of translated IV versus Tc-25

• Non-uniform temperature distribution of the cells is a concern• Temp Coeff for Pmp tends running higher in magnitude by 0.05% to 0.1% absolute

when compared to indoor estimates at CFV• What is the average cell temperature during indoor/outdoor temp coeff testing? - See

Cliff Hansen et al, PVSC40• Repeatability of +/- 0.01%/ C for Pmp temperature coefficient

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Sensor ßVmp (%/C)BS average -0.48

TC1 -0.52TC2 -0.42TC3 -0.42TC4 -0.55TC5 -0.49

Performance Model Coefficients

• SAPM– CFV follows the procedures established at SNL – work instructions will

be available later this year• Temperature Coefficients• Angle of Incidence• Electrical performance modelling (SAND2004-3535)

• .PAN file generation in partnership with CSE Fraunhofer– Multi-Irradiance and temperature data provided by CFV– .PAN file generation by CSE Fraunhofer– Recommend three representative modules for full test matrix

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Industry areas for improvement

• Reference cell calibration• 2.1 and 2.3% delta on outdoor ref cells measured at SNL and ISE• 2% delta on indoor ref cell measured at PTB and NREL• US calibration values lower in all three cases

• Temperature coefficient delta of 0.05% to 0.1% absolute• Results in a 1% to 2% prediction error at 45 C cell temperature

• Combined effect of RC and temp coeff could be as high as 4%• CEC temp coefficient limits are not consistent with those reported in the

Yingli RR• Why specify IEC 60904-3 spectrum for low irradiance testing?

• Is this likely in the real world?• What’s a reasonable alternative, given the labs can’t easily adjust spectrum

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Contact:

CFV Solar Test Laboratory, Inc.5600-A University Blvd SEAlbuquerque, NM 87106

Martin PlassSenior VP & General ManagerMartin.Plass@cfvsolar.com

+1 (505) 998-0102or

Customer Service atInfo@CFVSolar.com +1 (505) 998-0100

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Thank you !