NREL Pyrheliometer Comparisons (NPC)

NREL's Solar Radiation Research Laboratory performs annual comparisons of Absolute Cavity Radiometers Intercomparisons for transferring the World Radiometric Reference to international, national, and regional researchers. Reference Irradiances, Pictures, and Reports from the following NREL Pyrheliometer Comparisons (NPC) are available:

NPC-2024 (21 Sept - 27 Sept 2024)

Reference Irradiance (CSV 133 KB)
Pictures
Info Packet (PDF 926 KB)
NPC timing and data format (PDF 142 KB)
NPC Report (PDF 3.5 MB)
ACP/IRIS Report (PDF 1.12 MB)

NPC-2023 (25 Sept - 06 Oct 2023)

Reference Irradiance (CSV 129 KB)
Pictures Set A and Pictures Set B
Info Packet (PDF 1189 KB)
NPC timing and data format (PDF 142 KB)
NPC Report (PDF 3.1 MB)
ACP/IRIS Report (PDF 838 KB)
In Memoriam - Dr. Frank Vignola (PDF 178 KB)

NPC-2022 (26 Sept - 07 Oct 2022)

Reference Irradiance (CSV 70 KB)
Pictures Set A and Pictures Set B
Info Packet (PDF 893 KB)
NPC timing and data format (PDF 142 KB)
NPC Report (PDF 2.3 MB)
ACP/IRIS Report (PDF 583 KB)

NPC-2021 (04&29 November 2021)

Reference Irradiance (CSV 45 KB)
NPC Report (PDF 685 KB)

NPC-2019 (21 Sept - 27 Sept 2019)

Reference Irradiance (CSV 93 KB)
Pictures Set A and Pictures Set B
Info Packet (PDF 426 KB)
NPC Report (PDF 3.13 MB)
ACP/IRIS Report (PDF 485 KB)

NPC-2018 (24 Sept - 05 Oct 2018)

Reference Irradiance (CSV 69 KB)
Pictures Set A and Pictures Set B
Info Packet (PDF 2.63 MB)
NPC Report (PDF 2.85 MB)
ACP/IRIS Report (PDF 603 KB)

NPC-2017 (25 Sept - 06 Oct 2017)

Reference Irradiance (CSV 55 KB)
Pictures Set A and Pictures Set B
Info Packet (PDF 441 KB)
Report (PDF 4.15 MB)

NPC-2016 (26 Sept - 30 Sept 2016)

NPC-2014 (22 Sept - 26 Sept 2014)

Reference Irradiance (CSV 92 KB)
Pictures
Info Packet (PDF 586 KB)
Report (PDF 10.2 MB)

NPC-2013 (16 Sept - 27 Sept 2013)

Reference Irradiance (CSV 59 KB)
Pictures
Report (PDF 6.06 MB)

NPC-2012 (24 Sept - 05 Oct 2012)

NPC-2011 (19 Sept - 24 Sept 2011)

Reference Irradiance (CSV 85 KB), Picture Set A, and Picture Set B

NPC-2009 (28 Sept - 01 Oct 2009)

Reference Irradiance (CSV 81 KB) and Pictures

NPC-2008 (22 Sept - 27 Sept 2008)

Reference Irradiance (CSV 101 KB), Pictures, and Report (PDF 2.7 MB)

NPC-2007 (24 Sept - 27 Sept 2007)

Reference Irradiance (CSV 79 KB) and Pictures

NPC-2006 (25 Sept - 01 Oct 2006)

Reference Irradiance (CSV 112 KB) and Pictures

NPC-2004 (27 Sept - 11 Oct 2004)

Reference Irradiance (CSV 35 KB), Pictures and Info Packet (PDF 429 KB)

NPC-2003 (22-24 September 2003)

Reference Irradiance (CSV 60 KB) and Report (PDF 1.2 MB)

NPC-2002 (23-27 September 2002)

Reference Irradiance (CSV 25 KB), Pictures, and Report (PDF 1.4 MB)

NPC-2001 (24-28 September 2001)

Reference Irradiance (CSV 60 KB), Pictures, and Report (PDF 1.8 MB)

NPC-1999 (04-10 October 1999)

Reference Irradiance (CSV 56 KB), Pictures, and Report (PDF 1.2 MB)

NPC-1998 (07 October 1998)

Reference Irradiance (CSV 22 KB)

NPC-1997 (16 October 1997)

Reference Irradiance (CSV 15 KB)

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