The device is simple: it is a transparent 1.5-2l plastic bottle, as typically used for carbonated drinks, filled with water plus a little bleach to inhibit algal growth, fitted through the roof of a house. During daytime the water inside the bottle refracts sunlight, delivering about as much light as a 40- to 60-watt incandescent bulb to the interior. A properly installed solar bottle can last up to 5 years. The Solar Bottle Bulb is installed in the roof of homes with the purpose of refracting sunlight in order to light up a room. The project’s innovation lies in its utilization of cheap, durable and readily available materials to produce high quality natural lighting enabling the urban poor to have access to an affordable, environmentally friendly long-term alternative to electric light.