This is in fact quite simple, but extremely ingenius and effective - the automatic on / off interior solar lamp - invented in Brasil by Mr Alfredo Moser, a mecanics worker in a humble environment !

In 2002, during a long electrical shortage, at Uberaba, São Paulo, Brasil, Mr Alfredo Moser discovered a way to gather sun light in the house through plastic bottles hanging from the roof. First shown at the Globo Reporter in the 25th May 2007.

Alfredo Moser was pressed by a scarce electricity substitution and found out that he could light his house with a bottle of water filled with water and a protection cap made of camera film.

Mr Moser recommends a bottle filled with Clean water, and 2 caps of "sanitary water" to prevent any mold growing.

The bottle is just refracting sunlight very effectively and produces an equivalent light power compared to a 50/60W lamp. In a rainy day, even without much light and direct sun, one still have some light.

Is there a challenge here?

Perhaps a sound scientific approach and refinment could bring new developments and powerfull applications do this ingenius idea !