Solar position and intensity calculator
 

I am trying to setup a weather station and have a solar sensor. What I
would like to find is a calculator which shows me the maximum expected
solar radiation in w/m2 for my latitude and longitude throughout the day. I
have found a US website which unfortunatly is down right now. So does
anyone know of a UK site or perhaps a spreadsheet (Excel or other)
calculator for the same job which I can obtain?

Stuart