Significant Improvements in Pyranometer Nighttime Offsets Using High-Flow DC Ventilation

Journal Article · Tue Jun 20 00:00:00 EDT 2017 · Journal of Atmospheric and Oceanic Technology

DOI:https://doi.org/10.1175/JTECH-D-16-0224.1· OSTI ID:1364678

Michalsky, Joseph J. ^[1]; Kutchenreiter, Mark ^[2]; Long, Charles N. ^[1]

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1. Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, and NOAA/Earth System Research Laboratory, Boulder, Colorado
2. National Renewable Energy Laboratory, Golden, Colorado

Abstract Ventilators are used to keep the domes of pyranometers clean and dry, but they affect the nighttime offset as well. This paper examines different ventilation strategies. For the several commercial single-black-detector pyranometers with ventilators examined here, high-flow-rate [50 cubic feet per minute (CFM) and higher] 12-VDC (where VDC refers to voltage direct current) fans lower the offsets, lower the scatter, and improve the predictability of the offsets during the night compared with lower-flow-rate (35 CFM) 120-VAC (where VAC refers to voltage alternating current) fans operated in the same ventilator housings. Black-and-white pyranometers sometimes show improvement with DC ventilation, but in some cases DC ventilation makes the offsets slightly worse. Since the offsets for these black-and-white pyranometers are always small, usually no more than 1 W m−2, whether AC or DC ventilated, changing their ventilation to higher CFM DC ventilation is not imperative. Future work should include all major manufacturers of pyranometers and unventilated and ventilated pyranometers. An important outcome of future research will be to clarify under what circumstances nighttime data can be used to predict daytime offsets.

• Research Organization: National Renewable Energy Lab. (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Wind and Water Technologies Office (EE-4W)
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1364678
• Alternate ID(s): OSTI ID: 1369124
• Report Number(s): NREL/JA-5D00-67398
• Journal Information: Journal of Atmospheric and Oceanic Technology, Journal Name: Journal of Atmospheric and Oceanic Technology Vol. 34 Journal Issue: 6; ISSN 0739-0572
• Publisher: American Meteorological Society
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
47 OTHER INSTRUMENTATION
pyranometer
offsets
climate records
data processing
in situ atmospheric observations
instrumentation/sensors
quality assurance/control
surface observations