Some tools I found

South Africa

If you have an Outback controller, their tool is a great eye opener: http://www.outbackpower.com/outback-resources/string-sizing-tool

If you have an Tristar controller: http://98.115.2.6/en/strings/calc.php

SunnyBoy: http://www.sunnydesignweb.com/sdweb/SunnyDesign/Home

And I found these calculators to help guide one, in Excel. 13 and 14 the most help: http://electricalnotes.wordpress.com/2011/05/28/electrical-programs-excel-base/