Using the hourly solar energy values provided by the NSRDB 10km-grid, 8 years (1998-2005) of hourly tilted plane estimates are computed and converted to monthly and annual averages over this period. As noted below, several calculation steps are pre-processed in an effort to minimize the on-demand computations performed by the server.
Global Horizontal Irradiance data obtained from the National Solar Radiation Database (NSRDB) . Specifically the data product used was the SUNY 10-km gridded data from the 1991-2005 Update.
Computations of irradiance on a tilted plane use an algorithm described by J. Page in the book
Practical handbook of photovoltaics: fundamentals and applications By T. Markvart, Luis Castaņer
Solar Geometry is computed using the NREL Solar Position Algorithm . Pre-processed.
Clear Sky Radiation is computed using the Kasten Clear Sky Model modified by Ineichen et al. (2002).
See journal article
A new airmass independent formulation for the Linke turbidity coefficient. Solar Energy Volume 73, Issue 3, September 2002, Pages 151-157. Pre-processed.
Altitude information was obtained from the GLOBE Digital Elevation Model. Pre-processed.
Linke Turbidity information was obtained from the SoDa Service. Pre-processed.