Standardization News

Indoor Calibration Transfer

Manufacturers of solar radiometers and testing laboratories for solar energy, materials and durability testing will be among the primary users of a new ASTM International standard that outlines procedures using indoor test methods to calibrate radiometers with dissimilar detectors.

The new standard, G207, Test Method for Indoor Transfer of Calibration from Reference to Field Pyranometers, was developed by Subcommittee G03.09 on Radiometry, part of ASTM International Committee G03 on Weathering and Durability. G207 facilitates calibration of solar sensors used in accelerated testing under simulated sunlight and outdoor weathering tests as well as performance monitoring of solar energy conversion systems.

Daryl Myers, a senior scientist at the National Renewable Energy Laboratory, and the chairman of G03.09, says that the most important practical implication of G207 is that transfer between an expensive, well-calibrated thermopile instrument and much cheaper solid state devices can be accomplished indoors, when properly conducted, with computable uncertainty.

"Calibration becomes independent of weather and outdoor conditions," says Myers. "The process permits calibration of a large number of inexpensive sensors with respect to a single expensive reference radiometer more quickly."

Myers notes that manufacturers and users of radiometers are encouraged to join in the standards developing activities of G03.09.

To purchase ASTM standards, visit and search by the standard designation number or contact ASTM Customer Relations (phone: 610-832-9585;

CONTACT Technical Information: Daryl Myers, National Renewable Energy Laboratory • Golden, Colo. • Phone: 303-384-6768 O ASTM Staff: Jeffrey Adkins • Phone: 610-832-9738 O Upcoming Meeting: Jan. 29-31, 2012 • January Committee Week • Atlanta, Ga.

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