Liter of Light is a global open source movement aiming to provide ecologically sustainable and cost-free lighting for simple dwellings with thin roofs. The device is simple: a transparent 1.5–2 L plastic bottle, as typically used for carbonated drinks, is filled with water plus a little bleach to inhibit algal growth and fitted into a hole in a roof. The device functions like a deck prism: during daytime the water inside the bottle refracts sunlight, delivering about as much light as a 40–60 watt incandescent bulb to the interior. A properly installed solar bottle can last up to 5 years.

Light up dark areas in your home during daytime using this concept. Recycle used clear plastic soda bottles, add water and bleach, then install. After installation the solar light bulb can provide approximately 55 watts of light from the sun.  The Plastic Index introduced and launched the Solar Bottle Bulb in South Africa during World Design Capital Cape Town 2014.

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