Liter of Light, a project of the Philippines-based nonprofit MyShelter Foundation, provides light to poor households around the world with limited or no access to electricity ? by collecting plastic bottles, filling them with water and bleach, and sticking them into roofs. The bleach-filled bottles then refract the light from outdoors into the house, lighting up much like a lightbulb. To make the bottles work at night a small LED lightbulb is slipped into the bottle, which in turn is hooked up to a mini-solar panel.
http://www.huffingtonpost.com.au/entry/plastic-bottles-electricity_us_596e64f4e4b0000eb1968bb5