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Title: Developing a spectroradiometer data uncertainty methodology

The proper calibration and measurement uncertainty of spectral data obtained from spectroradiometers is essential in accurately quantifying the output of photovoltaic (PV) devices. PV cells and modules are initially characterized using solar simulators but field performance is evaluated using natural sunlight. Spectroradiometers are used to measure the spectrum of both these light sources in an effort to understand the spectral dependence of various PV output capabilities. These chains of characterization and measurement are traceable to National Metrology Institutes such as National Institute of Standards and Technology, and therefore there is a need for a comprehensive uncertainty methodology to determine the accuracy of spectroradiometer data. In this paper, the uncertainties associated with the responsivity of a spectroradiometer are examined using the Guide to the Expression of Uncertainty in Measurement (GUM) protocols. This is first done for a generic spectroradiometer, and then, to illustrate the methodology, the calibration of a LI-COR 1800 spectroradiometer is performed. The reader should be aware that the implementation of this methodology will be specific to the spectroradiometer being analyzed and the experimental setup that is used. Depending of the characteristics of the spectroradiometer being evaluated additional sources of uncertainty may need to be included, but the generalmore » GUM methodology is the same. Several sources of uncertainty are associated with the spectroradiometer responsivity. Major sources of uncertainty associated with the LI-COR spectroradiometer are noise in the signal at wavelengths less than 400 nm. At wavelengths more than 400 nm, the responsivity can vary drastically, and it is dependent on the wavelength of light, the temperature dependence, the angle of incidence, and the azimuthal orientation of the sensor to the light source. As a result, the expanded uncertainties in the responsivity of the LI-COR spectroradiometer in the wavelength range of 400-1050 nm can range from 4% to 14% at the 95% confidence level.« less
Authors:
 [1] ;  [1] ;  [2] ;  [2]
  1. Univ. of Oregon, Eugene, OR (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Report Number(s):
NREL/JA-5D00-67469
Journal ID: ISSN 0038-092X
Grant/Contract Number:
AC36-08GO28308
Type:
Published Article
Journal Name:
Solar Energy
Additional Journal Information:
Journal Volume: 149; Journal Issue: C; Journal ID: ISSN 0038-092X
Publisher:
Elsevier
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 47 OTHER INSTRUMENTATION; calibration; measurement uncertainty; spectral data; spectroradiometer; responsivity; cosine response; LI-COR 1800
OSTI Identifier:
1351024
Alternate Identifier(s):
OSTI ID: 1355138