For anyone thinking of adding a bit of solar heat to their shop, I've
put up a web page (link below) with monthly maps showing how much
solar energy is delivered to locations in the USA. The data represents
a 30-year average.

If you're not in the USA, you may be able to find that information at
www.nrel.gov

At the bottom of the page there's a link that can be used in
conjunction with the map data to predict the heat output from a
south-facing vertical panel. The program will run under Windows or
MS-DOS (apologies to others; but this is a Windows box).

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/SolarEnergy.html