I'll put some useful data sources as I find them. This will be in addition to the general links on the side of the site (so I won't have the GCM links here).
Solar Irradiance Data
http://www.geo.fu-berlin.de/en/met/ag/strat/forschung/SOLARIS/Input_data/
Site found through comments on RC (here)
http://lasp.colorado.edu/lisird/tsi/historical_tsi.html
