Refraction Makes Water a Daylight Transmitter!

Water's refraction properties can bend sunlight, concentrate it and deliver the concentrated sunlight to areas where sunlight cannot naturally reach.

Refraction

Source
- chemicalparadigms.wikispaces.com

Refraction is the change in direction of a light wave that occurs when materials with different refraction properties transmit the light wave.
The refraction - change in direction - occurs at the point where one material meets another.
Refraction occurs when the light hits the surface of a new medium at an angle other than at 90 degrees i.e. the light does not hit the surface of the medium perpendicularly.
By putting different mediums in the path of a light ray, the ray can be bent to arrive at a location that the original ray cannot reach.
Lighting up a room in Brazil

Source - doorknob.com

Shacks with corrugated metal roofing and no electric connection are usually very dark places.

Source - doorknob.com

A solar bottle installed in a hole in the roof can help.
This is a sealed bottle half full of water and installed so that the water surface in the bottle is in line with the roof's outside surface.

Source - doorknob.com

When sunlight shines on the bottle, water in the bottle captures and concentrates the light and, in effect, acts as an electricity bulb installed in the roof of the shack.
To keep the water clean, a few spoonfuls of chlorine is added to the water. This water-chlorine mixture can provide light for a number of years.