North Carolina Solar Center:

http://www.ncsc.ncsu.edu

http://www.seia.org/taxmanualdownload.php

http://www.energy.gov/

Consumer's Guide : Evaluating Your Site's Solar Resources For Solar Water Heating:

http://www.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=12870

http://www.environ.ie/en/

http://rredc.nrel.gov/solar/