The video above shows how a man in an impoverished urban area in the Philippines created a solar light to brighten the densely packed windowless homes that are dark inside even when the sun is shining brightly. The method involves making a roof cutout to support the bottle and filling the bottle with water and a little bleach. This solution can also help add some light to garden sheds and any other type of small outbuilding without electricity.
Video by Marlon Bucsit.
Once a cutout is made in the metal roofing material, the soft drink bottle is attached and a sealant is applied. Then the bottle is filled with water and a teaspoon or so of bleach is added to kill any bacteria in the water.
The Filipino man serves as an example that life hacking can exist anywhere. Because of one bright idea, he has a business and hundreds of people have a cheap way to bring light into their lives.
Using a Soda Bottle As a Solar Light Source [California Examiner]