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

Mark Kutchenreiter, Aron Habte, J.J. Michalsky, C.N. Long

Research output: NRELPoster


Accurate solar radiation measurements using pyranometers are required to understand radiative impacts on the Earth's energy budget, solar energy production, and to validate radiative transfer models. Ventilators of pyranometers, which are used to keep the domes clean and dry, also affect instrument thermal offset accuracy. This poster presents a high-level overview of the ventilators for single-black-detector pyranometers and black-and-white pyranometers. For single-black-detector pyranometers with ventilators, high-flow-rate (50-CFM and higher), 12-V DC fans lower the offsets, lower the scatter, and improve the predictability of nighttime offsets compared to lower-flow-rate (35-CFM), 120-V AC fans operated in the same type of environmental setup. Black-and-white pyranometers, which are used to measure diffuse horizontal irradiance, sometimes show minor improvement with DC fan ventilation, but their offsets are always small, usually no more than 1 W/m2, whether AC- or DC-ventilated.
Original languageAmerican English
StatePublished - 2017

Publication series

NamePresented at the NOAA ESRL Global Monitoring Annual Conference 2017, 23-24 May 2017, Boulder, Colorado

NREL Publication Number

  • NREL/PO-5D00-68517


  • black-and-white
  • measurement
  • pyranometer
  • single-black-detector
  • solar radiation
  • ventilator


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