Concentrating solar power, which has been around for decades,

   is one of the most promising techniques being tried today to make
   solar electricity more cost effective.

   The concept is simply to focus light in order to boost electricity output.
   But there's a wide disparity in the types of solar concentrators being built,
   from utility-scale solar thermal projects to specialized photovoltaic
   solar panels that could one day go on a homeowner's roof.

   Solar concentrators use lenses, mirrors, parabolic dishes or other optics
   to concentrate energy from the sun. Very often, they have a mechanism,
   so that these devices track the path of the sun during the day.
   Concentration of light is achieved with mirrors (reflection) or,
   with transparent lens (refraction). Cameras and small telescopes use lenses,
   large telescopes use mirrors.A mirror reflects incoming light so that the
   angle of the reflected ray is equal
   to the angle of the incident ray