Thousands of poor homes in Manila have a problem, not uncommon for cramped and small settlements. These houses are so close together, with metal roofing that all the light is blocked off and no light reaches the homes even during daylight!
The solar bottle is a simple bottle bulb, usually a 1 liter soda bottle that is filled with a solution of purified water and bleach. The bottle is inserted halfway through a hole drilled in the metal roof and its sides are sealed. The whole deal looks like a bulb through a sunroof and provides a good amount of light by deflecting sunlight into gloomy interiors.
The chlorine and bleach “poisons” the water to keep molds from developing so the solution can last up to five years. The clear and purified water helps disperse the light through refraction, so the light is not concentrated. It only costs $2-3 to make a solar bottle bulb that is bringing light to dark homes.
Source: ecopreneurist.comAdded: 13 June 2012