Info about solar throughs
Think of solar troughs as a way to concentrate sunlight-energy onto a small volume, thus creating intense heat. This heat can be used to power a turbine, i.e. electric generator.
There are sme nice pictures and explanations available on the web. Check out the links below:

 
 

Links:

ISC - International Solar Collectors Inc.

How Solar Troughs Can Make Inexpensive Electricity : http://www.chatlink.com/~soltherm/hitwrks.htm

Desalination via solar through: http://www.chatlink.com/~soltherm/desal.htm