Should ghee be kept out of light?
According to IndiaCurry, it should be stored in containers opaque to ultraviolet light for long term storage:


  The UV rays from sunlight, florescent lights, and other sources
  accelerate oxidation process. The storage container container for ghee
  must be opaque to filter out UV rays. Preferably ghee must be stored
  in a dark place


I was unable to find credible sources with more detailed information that indicate exactly how this affects storage life.  In fact, it was hard to find any references at all--most were far more concerned with keeping it from being exposed to air (oxygen).

However, as it is such an easy thing to arrange--just put the jar in a cabinet for example, or use an amber glass jar--that it seems worth doing.  My guess is that in practice, unless you are using your ghee very slowly, or have an extraordinarily large amount, that it makes very little difference, but again its easy, so why not?

I did find lots of references to using ghee in lamps--this is the power of Google! :-)