Parabolic trough

A parabolic trough is a type of solar thermal collector. It is constructed as a long parabolic mirror with a Dewar tube running its length at the focal point. Sunlight is reflected by the mirror and concentrated on the Dewar tube. Heat transfer fluid runs through the tube to absorb heat from the concentrated sunlight. It is the most widely used type of solar power. It is usually aligned on a north south axis.

The largest operational solar power system at present is of this type. Named SEGS, it is located at [Kramer Junction] in California, USA.