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. Reports and Pictures from the following NREL Pyrheliometer Comparisons (NPC) are available:
NPC-1999 (04-10 October 1999): Pictures and Report (1.1 MB PDF Document)
NPC-2001 (24-28 September 2001): Pictures and Report (15.0 MB PDF Document)
NPC-2002 (23-27 September 2002): Pictures and Report (10.9 MB PDF Document)
NPC-2003 (22-24 September 2003): Report (17.8 MB PDF Document)
NPC-2004 (27 Sept - 11 Oct 2004): Pictures and Info Packet (429 KB PDF Document)
