Mark,
Please take a look at the SAM compatible
EPW UK
.
Also, take a look at
Meteonorm
. Meteonorm can output in TMY2 or TMY3 format and SAM can read in either one of those.
Also, take a look at the
SWERA site
as well.
The SAM team does not create any weather data ourselves but receive it from other activities at NREL and other public sources.
Hope this helps,
Steve