I really appreciate the Sharp's LumiWall, a roof that is shaded glass in the daytime and transforms into an illuminated array of white at night. The concept behind LumiWall is that it stores solar energy in the daytime and works as a lighting system at night.
However, the thing that makes me scratch my head is that half of the light will be emitted outside and that would be the main drawback. Moreover, you cannot illuminate the whole house with this concept. Sharp should come out with a more creative view with the designing part. Atleast, they should find a solution for the light to be emitted in a single direction.
Still, I think the idea is pretty cool except few shortcomings.