You may have heard that NREL recently released a major revision to the National Solar Radiation Database (NSRDB), at https://nsrdb.nrel.gov/. The NSRDB now includes data for 2005 – 2012 developed using the Physical Solar Model, a different algorithm that was used to produce Version 2 (1991- 2005). How do the new NSRDB GHI data compare with ground measurements? Sandia recently published “Analysis of Global Horizontal Irradiance in Version 3 of the National Solar Radiation Database”, DOI: 10.13140/RG.2.1.3428.4006, which may be downloaded here: http://energy.sandia.gov/download/34915/ Other Sandia publications related to PV systems can be found here: http://energy.sandia.gov/energy/renewable-energy/solar-energy/photovoltaics/publications/