The Measurements and Instrumentation Team within the Distributed Energy Resources Center at the National Renewable Energy Laboratory, NREL, calibrates pyranometers for outdoor testing solar energy conversion systems. The team also supports climate change research programs. These activities led NREL to improve pyranometer calibrations. Low thermal-offset radiometers measuring the sky diffuse component of the reference solar irradiance removes bias errors on the order of 20 Watts per square meter (W/m2) in the calibration reference irradiance. Zenith angle dependent corrections to responsivities of pyranometers removes 15 to 30 W/m2 bias errors from field measurements. Detailed uncertainty analysis of our outdoor calibration process shows a 20% reduction in the uncertainty in the responsivity of pyranometers. These improvements affect photovoltaic module and array performance characterization, assessment of solar resources for design, sizing, and deployment of solar renewable energy systems, and ground-based validation of satellite-derived solar radiation fluxes.

Issue Section:
Technical Papers
Keywords:
atmospheric measuring apparatus, measurement errors, solar cell arrays, calibration, measurement uncertainty
Topics:
Actinometers, Calibration, Uncertainty
1.
Myers, D. R., 1988, “Uncertainty Analysis for Thermopile Pyranometer and Pyrheliometer Calibrations Performed by SERI,” Solar Energy Research Institute SERI/TR-215-3294.
2.
Myers
,
D. R.
,
Emery
,
K. A.
, and
Stoffel
,
T. L.
,
1989
, “
Uncertainty Estimates for Global Solar Irradiance Measurements Used to Evaluate PV Device Performance
,”
Sol. Cells
,
7
, pp.
455
–
464
.
3.
Myers, D. R., 1989, “Application of a Standard Method of Uncertainty Analysis to Solar Radiometer Calibrations,” Solar ’89 Technical Papers: Proc. of 1989 Annual Conf., American Solar Energy Society, pp. 445–449.
4.
Myers, D. R., and Stoffel, T. L., 1990, “A Description of the Solar Radiometer Calibration (RADCAL) Process at SERI,” Proc. of 1990 Annual Conf., American Solar Energy Society, pp. 171–177.
5.
NREL, 1997, RCC Radiometer Calibration and Characterization, NREL Metrology Manual.
6.
Dutton, E. G., Michalsky, J. J., Stoffel, T. L., Forgan, B. W., Hickey, J., Nelson, D. W., Alberta, T. L., and Reda, I., “Measurement of Broadband Diffuse Solar Irradiance Using Current Commercial Instrumentation with a Correction for Thermal Offset Errors,” J. Atmos. Ocean. Technol., in press.
7.
Stoffel
,
T. L.
,
Reda
,
I.
,
Myers
,
D. R.
,
Renne
,
D.
,
Wilcox
,
S.
, and
Treadwell
,
J.
,
2000
, “
Current Issues in Terrestrial Solar Radiation Instrumentation for Energy, Climate, and Space Applications
,”
Metrologia
,
37
, pp.
399
–
402
.
8.
Reda, I., and Myers, D., 1999, “Calculating the Diffuse Responsivity of Solar Pyranometers,” NREL Technical Report/TP-560-26483, National Renewable Energy Laboratory.
9.
Wilcox, S. M., Reda, I., Nelson, D. A., and Webb, C., 1999, “Traceability and Verification of Radiometer Calibrations at the Southern Great Plains Radiometer Calibration Facility,” Proc. of Ninth Annual ARM Science Team Meeting, N. Burleigh and D. Carrothers (eds.), U.S. Department of Energy, Richland, WA.
10.
Wilcox, S. M., and Stoffel, T. L., 1998, “Radiometer Calibrations at the ARM Southern Great Plains Radiometer Calibration Facility,” In Proc. of Eighth Annual ARM Science Team Meeting, N. Burleigh and D. Carrothers (eds.), U.S. Department of Energy, Richland, WA.
11.
Kendall
,
J. M.
, and
Berhdahl
,
C. M.
,
1970
, “
Two Blackbody Radiometers of High Accuracy
,”
Appl. Opt.
,
12
, pp.
1089
–
1091
.
12.
Willson
,
R. C.
,
1973
, “
Active Cavity Radiometer
,”
Appl. Opt.
,
12
, pp.
810
–
817
.
13.
WMO 1983, Guide to Meteorological Instruments and Methods of Observation WMO No. 8, Secretariat of the World Meteorological Organization, Geneva, Switzerland. 9.8, Sec. 9.3.1.1.
14.
Reda, I., 1996. “Calibration of a Solar Absolute Cavity Radiometer with Traceability to the World Radiometric Reference,” 79 pp., NREL Technical Report/TP-463-20619, National Renewable Energy Laboratory.
15.
ASTM 1997a, “Standard Test Method for Calibration of Pyrheliometers by Comparison to Reference Pyrheliometers,” ASTM E-816-95, 1997 Annual Book of ASTM Standards, Vol. 14. American Society for Testing and Materials, Conshohocken, MA.
16.
Zerlaut
,
G. A.
,
1986
, “
Solar Radiometry Instrumentation, Calibration, Techniques and Standards
,”
Sol. Cells
,
18
, pp.
189
–
203
.
17.
Zerlaut, G. A., 1989, “Solar Radiation Instrumentation,” in Solar Resources, R. Hulstrom (ed.), MIT Press, Cambridge, MA, pp. 203–208.
18.
ASTM 1997b, “Standard Method for Calibration of Reference Pyranometers with Axis Vertical by the Shading Method,” ASTM E-913-82. 1997 Annual Book of ASTM Standards, Vol. 14, American Society for Testing and Materials, Conshohocken, MA.
19.
Wardle, D. I., Dahlgren, L., Dehne, K., Liedquist, L., McArthur, L. J. B., Miyake, Y., Motschka, O., Velds, C. A., and Wells, C. V., 1996, “Improved Measurements of Solar Irradiance by Means of Detailed Pyranometer Characterization,” International Energy Agency Solar Heating and Cooling Program, Task 9 Report IEA-SHCP-9C-2, National Atmospheric Radiation Center, Atmospheric Environment Service, Downsville, Canada.
20.
Taylor, B. N., and Kuyatt, C. E., 1993, “Guidelines for Evaluating an Expressing the Uncertainty of NIST Measurement Results,” NIST Technical Note 1297, National Institute of Standards and Technology, Gaithersburg, MD.
21.
Gulbrandsen
,
A.
,
1978
, “
On the Use of Pyranometers in the Study of Spectral Solar Radiation and Atmospheric Aerosols
,”
J. Appl. Meteorol.
,
17
, pp.
899
–
904
.
22.
Molineaux
,
B.
,
Ineichen
,
P.
, and
O’Neill
,
N.
,
1998
, “
Equivalence of Pyhreliometric and Monochromatic Aerosol Optical Depths at a Single Key Wavelength
,”
Appl. Opt.
,
37
(
30
), pp.
7008
–
7018
.
23.
Myers, D. R., and Maxwell, E. L., 1992, “Hourly Estimates of Precipitable Water for Solar Radiation Models.” Burley, S., and Arden, M. E. (eds.), Solar 92: Proc. of 1992 Annual Conf., June 1992, American Solar Energy Society, Boulder, CO, pp. 317–322.
24.
Maxwell, E. L., and Myers, D. R., 1992, “Daily Estimates of Aerosol Optical Depth for Solar Radiation Models.” Burley, S., and Arden, M. E. (eds.), Solar ’92: Proc. of 1992 Annual Conf., June 1992, American Solar Energy Society, Boulder, CO, pp. 323–327.
25.
Michalsky
,
J.
,
1988a
, “
The Astronomical Almanac’s Algorithm for Approximate Solar Position (1950–2050)
,”
Sol. Energy
,
40
(
3
), pp.
227
–
235
.
26.
Michalsky
,
J.
,
1988b
, “
ERRATA: The Astronomical Almanac’s Algorithm for Approximate Solar Position (1950–2050)
,”
Sol. Energy
,
41
(
1
), p.
113
113
.
27.
John Fluke Mfg. Co., 1990, Helios Plus 2287A Data Acquisition Front End System Manual Vol 1.
28.
Reda, I., Stoffel, T., and Treadwell, J., 1999, NPC1999, “Results of NREL Pyrheliometer Comparisons NPC 1999,” NREL Internal Metrology Report.
29.
Iqbal, M., 1983, An Introduction to Solar Radiation, Academic Press, New York, p. 13.
30.
Zimmerman, J. C., 1981, “Sun Pointing Algorithms and Their Accuracy,” SAND81-0761, Experimental Systems Operation Division, 4721, Sandia National Laboratories, Albuquerque, NM.
Copyright © 2002
 by ASME
You do not currently have access to this content.