Solar Spectral Distributions
Explorations into alternative forms of energy have increased interest in standards for solar energy applications. ASTM International Committee G03 on Weathering and Durability has approved a new standard in this area, G197, Table for Reference Solar Spectral Distributions: Direct and Diffuse on 20° Tilted and Vertical Surfaces. ASTM G197 was developed by Subcommittee G03.09 on Radiometry.
“Research and development into fenestration glass technology requires a suitable standard for testing and reporting results, and publishing specifications for newly developed window products,” says Daryl Myers, senior scientist II in the Resource Integration Group of the Electricity, Resources and Buildings Integration Center at the National Renewable Energy Laboratory, and a member of G03. “These products generally contain materials, films or special recipe glass to reject or admit different spectral regions. These glasses are generally installed in vertical surfaces such as walls or skylight application in roofs. Thus it is appropriate to have meaningful geometry representing the relationships between the sun and the material as installed.”
Chris Gueymard, Solar Consulting Services, says G197 is based on SMARTS, the same solar radiation model that was used by G03.09 to develop two other solar-related standards: G173, Tables for Reference Solar Spectral Irradiances: Direct Normal and Hemispherical on 37° Tilted Surface, and G177, Tables for Reference Solar Ultraviolet Spectral Distributions: Hemispherical on 37° Tilted Surface. “Even though the three standards are different in scope and magnitude, their tables can be easily intercompared on a wavelength-to-wavelength basis,” says Gueymard. In addition to the standards, the SMARTS model is available through ASTM as an adjunct (ADJG173CD) to ASTM G173.
Building engineers, glass manufacturers, solar energy product manufacturers and testing laboratories are all potential users of G197 and the other G03.09 standards. Representatives from these sectors are invited to join in the ongoing standards developing activities of G03.09.
Technical Information: Daryl Myers, National Renewable Energy Laboratory, Golden, Colo.
ASTM Staff: Jeffrey Adkins