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Office of Energy Efficiency & Renewable Energy

Operated by the Alliance for Sustainable Energy, LLC

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Laboratory (NREL) at www.nrel.gov/publications.

Contract No. DE-AC36-08GO28308

Improved Rotating Shadowband 

Radiometer Measurement 

Performance

Cooperative Research and 

Development Final Report

CRADA Number: CRD-08-294

NREL Technical Contact: Afshin M. Andreas

CRADA Report

NREL/TP-5D00-63769

February 2015
NOTICE

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Cover Photos: (left to right) photo by Pat Corkery, NREL 16416, photo from SunEdison, NREL 17423, photo by Pat Corkery, NREL 

16560, photo by Dennis Schroeder, NREL 17613, photo by Dean Armstrong, NREL 17436, photo by Pat Corkery, NREL 17721.

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Cooperative Research and Development Final Report

In accordance with Requirements set forth in Article XI.A(3) of the CRADA document, this 

document is the final CRADA report, including a list of Subject Inventions, to be forwarded to 

the Office of Science and Technical Information as part of the commitment to the public to 

demonstrate results of federally funded research.

Parties to the Agreement: Irradiance, Inc.

CRADA Number: CRD-08-294

CRADA Title: Improved Rotating Shadowband Radiometer Measurement Performance

Joint Work Statement Funding Table Showing DOE Commitment:

Estimated Costs NREL Shared Resources

Year 1 $ 100,000.00

Year 2 $ 33,018.00

TOTALS $ 133,018.00

Abstract of CRADA Work:

Under this Agreement, NREL will work with Participant to improve rotating shadowband 

radiometer (RSR) performance characterizations. This work includes, but is not limited to, 

research and development (R&D) for making the RSR a more accurate and fully characterized 

instrument for solar power technology development and commercial solar power project site 

assessment. Cooperative R&D is proposed in three areas: instrument calibration, instrument field 

configuration and operation, and measurement extrapolation and interpolation using satellite 

images. This work will be conducted at NREL and Participant facilities.

Summary of Research Results:

Accurate solar radiation datasets are the foundation of a successful solar energy project and are 

critical in reducing the expense associated with mitigating performance risk of these projects. 

Further, as solar energy systems become more prevalent, accurate solar radiation datasets are

becoming critical because utility planners and grid system operators will need to understand how 

high penetrations of solar energy systems depend on a variable solar resource. NREL and 

Irradiance, Inc., through a cooperative R&D, improved the quality of data obtained from RSRs

by implementing up-to-date calibration and characterization techniques. Irradiance, Inc.

improved the RSR performance, calibration, field configuration, and operation, using the 

reference solar irradiance data from the Baseline Measurement System (BMS) at NREL’s Solar 

Radiation Research Laboratory (SRRL). These RSR improvements were tested and implemented 

at SRRL and over a dozen field installations. Some of the enhancements include improved 

sensor connections to allow sensors to be changed easily for calibration, creating a standardized 
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data logging program, and improving algorithms to compute solar irradiance. NREL also 

published a technical report (http://www.nrel.gov/docs/fy14osti/60896.pdf) on radiometric data 

evaluation from multiple instruments and the RSR with improved algorithm as part of the 

evaluation, and the result shows low MBE and RMSE compared to similar sensor with no 

improved algorithm. Further, the participant calibrated and characterized over 1,000 solar 

sensors by utilizing NREL–SRRL world class radiometric instrumentation infrastructure. The 

sensors were deployed alongside the SRRL instrumentation so that they could be calibrated and 

characterized using algorithms developed by the participant. These sensors were later used in 

field installations all over the world.

Solar irradiance data for BMS as well as the NREL-owned RSR can be found on the 

Measurement and Instrumentation Data Center (MIDC) web site

(http://www.nrel.gov/midc/srrl_bms/).

Subject Inventions Listing:

None

Report Date:

January 13, 2015

Responsible Technical Contact at Alliance/NREL:

Afshin M. Andreas

This document contains NO confidential, protectable, or proprietary information.