Hundreds of millions of people live in informal settlements worldwide. Many of these chockablock dwellings lack windows or adequate daylighting, and in tropical locales are often made darker by extended roofing favored for protection from rain and hot sun. Residents of informal settlements often resort to kerosene, candles, or inventive wiring for light, risking health and safety in the process. Many simply go without.

Proper electricity is not a common option, especially in the Philippines, which has the highest electricity rates in Asia. Filipino entrepreneur and activist Illac Diaz created Liter of Light to provide informal settlements in his country with a cheap daytime lighting source that can be produced and distributed locally.

We have to design for the grassroots.

The solution is Diaz’s figurative “liter of light,” a clear plastic soda bottle filled with water and installed in the roof as a skylight. The water refracts the sunlight as it streams through the bottle, dispersing the rays 360 degrees, thereby illuminating the entire room. The recipients of the solar bottle bulbs, who pay about $1 for the bulb and installation, save money on electricity and cut back on the use of kerosene, candles, and other fuels that are responsible for indoor air pollution and fire hazards.

Liter of Light is not a charity: It provides enough initial supplies and volunteers to generate interest, but its focus is on teaching a community how to manufacture and install the solar bottle bulbs, with the end goal of creating green microbusinesses.

Liter of Light is widely distributing the technical know-how to produce the solar bottle bulbs, and through a combination of social networking, community outreach, open-source sharing, and hands-on building, the organization has placed tens of thousands of these solar bottle bulbs in informal settlements worldwide.

The campaign started in the Philippines, but has spread beyond Southeast Asia to India, Nepal, South America, and Africa. To date, the solar bottle bulb has been installed in over 30,000 homes in the Philippines. Around the world, Diaz estimates the number of installations is roughly 110,000. There are small adaptations to the design along the way. “In Nepal they put a little bit of anti-freeze in the water so it doesn’t expand and contract,” said Diaz. “In Africa, in the thatched houses, we tied three plastic bottles together and put a stick in between to attach them to the roof.”

Liter of Light has mastered movement building—making music videos to teach bottle bulb construction, organizing volunteers via Facebook, and holding bicycle rallies to help deliver assembled bulbs to community programs that have attracted hundreds of volunteers and raised funds for the campaign internationally.

With an open-source model, an emphasis on cheap, locally available or scavenged materials, and strong social networks, Liter of Light has succeeded in creating a highly adaptable solution distributed on an impressive scale.

We have to design for the grassroots.
A Liter of Light installed in a typical metal roof. The “solar bottle bulb” refracts sunlight to illuminate dark rooms. Credit: Jeminah FerrerLiter of Light’s entrepreneurs like Mang Demi (pictured) have installed tens of thousands of lights in Manila. Credit: Joey de LeonThe solar bottle bulb’s simple design means that hundreds can be fabricated in a day using unskilled workers or volunteers.A Liter of Light can provide the equivalent of a 55-watt bulb. Credit: Jun de LeonA worker installs a Liter of Light using only basic power tools and epoxy.For a Manila shopkeeper a Liter of Light eliminates the need for electricity during the day and thereby increases her profits. Credit: Joey de LeonPreviously unemployed workers collect discarded soda bottles to be repurposed as solar bottle bulbs.Volunteer groups have helped bring Liter of Light to more than a dozen countries around the world.
Manila, Philippines
Illac Diaz
Turn a Soda Bottle Into a Solar Light
51 Middleweight
54 Sumo
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An international network of locally manufactured sources of energy-free lighting