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Title: Physically based correction of systematic errors of Rotating Shadowband Irradiometers

Abstract

Accurate measurements of direct normal, diffuse horizontal and global horizontal irradiance (DNI, DHI and GHI) are needed for meteorological studies and are essential for the solar resource assessment at potential solar power plant sites. Often, these potential sites are remote and hence require robust sensors that require minimal maintenance that are not affected strongly by soiling. Therefore, Rotating Shadowband Irradiometers (RSI) are widely used for resource assessment. To achieve the required accuracy, corrections for the raw values of RSIs depending on systematic temperature, incidence angle and spectral errors must be used, and a thorough calibration of the sensor head must be applied. The existing correction functions are derived from comparisons of RSIs to thermopile radiometers at selected sites and therefore empirical. Their accuracy is considered to be site dependent. In this work a new correction and calibration method is presented that removes the systematic errors using a physical approach. It is based on information of the sensor properties as well as measurements of its directional response, and incorporates the atmospheric conditions at the measurement site. In this case, no empiric relations obtained from a specific site are required. The method requires estimates of the current DHI and GHI spectra duringmore » each measurement of the RSI. Based on these spectra, a spectral correction, which includes a spectrum dependent temperature correction, can be made without employing empirical relationships. The new physical calibration and correction method is tested at three sites and reaches similar results compared to the empirical functions. This is already achieved with rudimentary estimations of the GHI and DHI spectra and we expect that these estimations can be improved in the future. The results indicate that the physical approach reduces the problematic location dependence of the current calibration and correction methods. The physical correction and calibration method show promise for a further improvement of the RSI accuracy.« less

Authors:
 [1];  [1];  [2];  [1];  [3];  [4];  [4];  [5];  [6];  [7];  [8]
  1. German Aerospace Center (DLR), Tabernas/Almeria (Spain). Inst. of Solar Research
  2. Photovoltaic Performance Labs, Freiburg (Germany)
  3. CSP Services, Almeria (Spain)
  4. NTPC Ltd., Gautam Budh Nagar (India). NETRA, E3 Ecotech II
  5. Hochschule fur Technik, Stuttgart (Germany)
  6. Univ. of Oregon, Eugene, OR (United States)
  7. Research Centre for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Energy Dept., Renewable Energy Division
  8. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1665793
Report Number(s):
NREL/JA-5D00-77334
Journal ID: ISSN 0941-2948; MainId:26280;UUID:06b06630-cd95-46c1-92de-02aef2165818;MainAdminID:14062
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Accepted Manuscript
Journal Name:
Meteorologische Zeitschrift (Berlin)
Additional Journal Information:
Journal Name: Meteorologische Zeitschrift (Berlin); Journal Volume: 29; Journal Issue: 1; Journal ID: ISSN 0941-2948
Publisher:
Schweizerbart Science Publishers
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION; pyranometer; radiometer calibration; rotating shadowband radiometer; spectral error

Citation Formats

Forstinger, Anne, Wilbert, Stefan, Driesse, Anton, Hanrieder, Natalie, Affolter, Roman, Kumar, Sharad, Goswami, Neeraj, Geuder, Norbert, Vignola, Frank, Zarzalejo, Luis, and Habte, Aron. Physically based correction of systematic errors of Rotating Shadowband Irradiometers. United States: N. p., 2020. Web. doi:10.1127/metz/2019/0972.
Forstinger, Anne, Wilbert, Stefan, Driesse, Anton, Hanrieder, Natalie, Affolter, Roman, Kumar, Sharad, Goswami, Neeraj, Geuder, Norbert, Vignola, Frank, Zarzalejo, Luis, & Habte, Aron. Physically based correction of systematic errors of Rotating Shadowband Irradiometers. United States. https://doi.org/10.1127/metz/2019/0972
Forstinger, Anne, Wilbert, Stefan, Driesse, Anton, Hanrieder, Natalie, Affolter, Roman, Kumar, Sharad, Goswami, Neeraj, Geuder, Norbert, Vignola, Frank, Zarzalejo, Luis, and Habte, Aron. Wed . "Physically based correction of systematic errors of Rotating Shadowband Irradiometers". United States. https://doi.org/10.1127/metz/2019/0972. https://www.osti.gov/servlets/purl/1665793.
@article{osti_1665793,
title = {Physically based correction of systematic errors of Rotating Shadowband Irradiometers},
author = {Forstinger, Anne and Wilbert, Stefan and Driesse, Anton and Hanrieder, Natalie and Affolter, Roman and Kumar, Sharad and Goswami, Neeraj and Geuder, Norbert and Vignola, Frank and Zarzalejo, Luis and Habte, Aron},
abstractNote = {Accurate measurements of direct normal, diffuse horizontal and global horizontal irradiance (DNI, DHI and GHI) are needed for meteorological studies and are essential for the solar resource assessment at potential solar power plant sites. Often, these potential sites are remote and hence require robust sensors that require minimal maintenance that are not affected strongly by soiling. Therefore, Rotating Shadowband Irradiometers (RSI) are widely used for resource assessment. To achieve the required accuracy, corrections for the raw values of RSIs depending on systematic temperature, incidence angle and spectral errors must be used, and a thorough calibration of the sensor head must be applied. The existing correction functions are derived from comparisons of RSIs to thermopile radiometers at selected sites and therefore empirical. Their accuracy is considered to be site dependent. In this work a new correction and calibration method is presented that removes the systematic errors using a physical approach. It is based on information of the sensor properties as well as measurements of its directional response, and incorporates the atmospheric conditions at the measurement site. In this case, no empiric relations obtained from a specific site are required. The method requires estimates of the current DHI and GHI spectra during each measurement of the RSI. Based on these spectra, a spectral correction, which includes a spectrum dependent temperature correction, can be made without employing empirical relationships. The new physical calibration and correction method is tested at three sites and reaches similar results compared to the empirical functions. This is already achieved with rudimentary estimations of the GHI and DHI spectra and we expect that these estimations can be improved in the future. The results indicate that the physical approach reduces the problematic location dependence of the current calibration and correction methods. The physical correction and calibration method show promise for a further improvement of the RSI accuracy.},
doi = {10.1127/metz/2019/0972},
journal = {Meteorologische Zeitschrift (Berlin)},
number = 1,
volume = 29,
place = {United States},
year = {2020},
month = {3}
}

Journal Article:
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Figures / Tables:

Figure 1 Figure 1: Left: Reichert Rotating shadowband irradiometer in rest position. Right: CSPS Twin RSI during the rotation.

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