Lighting up homes with PET bottles

Attach a PET bottle filled with water and bleaching powder on an asbestos roof, and lo... there is light. The 'bottle bulb' is proving to be an ecological and sustainable source of light during day time — the water inside the bottle refracts sunlight hitting the roof and lights up the room below with an intensity of a 55 watt light bulb. Residents of Ejipura have been introduced to this 'elementary' way of lighting up their lives by Liter of Light (LOL) — a global open source movement that provides slums and other areas having erratic power supply with these eco-friendly 'bulbs'.