ASTM G167-15
Standard Test Method for Calibration of a Pyranometer Using a Pyrheliometer

Standard No.

ASTM G167-15

Release Date

2015

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM G167-15(2023)

Latest

ASTM G167-15(2023)

Scope

4.1 The pyranometer is a radiometer designed to measure the sum of directly solar radiation and sky radiation in such proportions as solar altitude, atmospheric conditions and cloud cover may produce. When tilted to the equator, by an angle β, pyranometers measure only hemispherical radiation falling in the plane of the radiation receptor.

4.2 This test method represents the only practical means for calibration of a reference pyranometer. While the sun-trackers, the shading disk, the number of instantaneous readings, and the electronic display equipment used will vary from laboratory to laboratory, the method provides for the minimum acceptable conditions, procedures and techniques required.

4.3 While, in theory, the choice of tilt angle (β) is unlimited, in practice, satisfactory precision is achieved over a range of tilt angles close to the zenith angles used in the field.

4.4 The at-tilt calibration as performed in the tilted position relates to a specific tilted position and in this position requires no tilt correction. However, a tilt correction may be required to relate the calibration to other orientations, including axis vertical.

Note 1: WMO High Quality pyranometers generally exhibit tilt errors of less than 0.58201;%. Tilt error is the percentage deviation from the responsivity at 0° tilt (horizontal) due to change in tilt from 0° to 90° at 1000 W·m²3.

4.5 Traceability of calibrations to the World Radiometric Reference (WRR) is achieved through comparison to a reference absolute pyrheliometer that is itself traceable to the WRR through one of the following:

4.5.1 One of the International Pyrheliometric Comparisons (IPC) held in Davos, Switzerland since 1980 (IPC IV). See Refs (3-7).

4.5.2 Any like intercomparison held in the United States, Canada or Mexico and sanctioned by the World Meteorological Organization as a Regional Intercomparison of Absolute Cavity Pyrheliometers.

4.5.3 Intercomparison with any absolute cavity pyrheliometer that has participated in either and IPC or a WMO-sanctioned intercomparison within the past five years and which was found to be within ±0.48201;% of the mean of all absolute pyrheliometers participating therein.

4.6 The calibration method employed in this test method assumes that the accuracy of the values obtained are independent of time of year, with the constraints imposed and by the test instrument's temperature compensation circuit (neglecting cosine errors).

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ASTM G167-15 Referenced Document

• ASTM E772 Standard Terminology Relating to Solar Energy Conversion
• ASTM E824 Standard Test Method for Transfer of Calibration From Reference to Field Radiometers

ASTM G167-15 history

• 2023 ASTM G167-15(2023) Standard Test Method for Calibration of a Pyranometer Using a Pyrheliometer
• 2015 ASTM G167-15 Standard Test Method for Calibration of a Pyranometer Using a Pyrheliometer
• 2005 ASTM G167-05(2010) Standard Test Method for Calibration of a Pyranometer Using a Pyrheliometer
• 2005 ASTM G167-05 Standard Test Method for Calibration of a Pyranometer Using a Pyrheliometer
• 2000 ASTM G167-00 Standard Test Method for Calibration of a Pyranometer Using a Pyrheliometer