Fast Company

The World's Cheapest Lightbulb Is Made Of Just A Plastic Bottle

In places where there is no grid, houses can be dark. But a simple solution--a plastic bottle stuck in the roof--can light up a room.

bottle lightbulb

We have lightbulbs made from glowing metal filaments, fluorescent gas, and LED diodes. And now we have one made of water. There is also a virtually unlimited supply since the "bulb" is composed of nothing more than one-liter plastic bottle, water, and bleach. The simple technology can be installed in less than an hour, lasts for five years, and is equivalent to a 60-watt bulb.

It works simply: The water defracts the light, letting it spread throughout the house instead of focusing on one point. The bleach keeps the water clear and microbe-free.

Adapted by students from the Massachusetts Institute of Technology focused on "appropriate technologies," the solar bottle bulb is illuminating poor settlements across the Philippines, where the organization Isang Litrong Liwanag ("A Liter of Light") has already installed 10,000 of them. “With the Solar Bottle Bulb project, a brighter Philippines is going to become a reality,” Illac Diaz, a social entrepreneur installing the bulbs, told a Filipino publication. You can watch a video of the bulbs in action here.

Millions of poor homes in Manila--and far more around the world--are left in the dark because metal roofs block all light and there are no connections to the electrical grid in cramped informal settlements. This simple bottle bulb, installed through a sealed hole cut in the metal roofs, provides a surprising amount of light by deflecting sunlight into gloomy interiors.

It's just one more innovation in the growing movement to design appropriate technologies for the developing world, where a little ingenuity goes further than a lot of technology.

Update: We've also learned that this organization and others in Brazil originally developed and have worked with water bottle lightbulb technology for more than a decade.

[Image: Isang Litrong Liwanag]

[Hat tip: How Stuff Works Blog]

Reach Michael J. Coren via Twitter or email.

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18 Comments

  • Ian B

    Certainly not a new idea, but it also wouldn't be to hard to retrofit the caps on these with a super-bright LED element linked to a solar cell and a battery, for night time.

  • Muhammad Ahsan Shafiq

    Yes Mr. Armando it will. I think Disaster Management agencies in different countries should adopt this product in their rescue package. Pakistan was hit by an earthquake in 2005 and as I mentioned the floods in 2010. Now combine the rehabilitation efforts with electricity shortage and imagine the situation of the country. Such initiatives would actually mitigate a huge problem of Pakistanis living in inferior areas and this would enable schools to sprout with even less resources. It would be a wow for schools and homes at the Northern region as they are best for eco-friendly initiatives such as solar cells.

  • Armando Ello

    Most of these comments are about the technique, but this really is a drastic change for the poor. in my belief this could unchain a real revolution for the people who live in those suburbs.

  • Muhammad Ahsan Shafiq

    I really liked the idea and after reading about it i thought more light could be sought if bottom of the bottle is increased or the whole bottle is replaced by a metal roof with a ' () ' shaped plastic body in the middle which will be filled with the same mix and will provide more light hence more savings. A year ago Pakistan was hit by a massive flood and ruined many houses in the lower regions of the country. I believe whenever there's chaos there's a business opportunity. I must say the Manila company should invest in Pakistan.

  • Detex

    I like the idea but calling it a "light bulb" is a bit misleading. It is more like a defused skylight then anything else... Why not just use a translucent roof or something similar in the first place? I know this is not economically feasible in retrofitting to older homes but if you are replacing a roof or building a new structure I think it is vastly superior...

  • assane

    marcos silva, wreunke,

    Great!!! i'm a senegalese citizen and i want to put them in my country. How its possible. Do i need an experience or a patent. please to give more information or a website where i can find it. People are suffering because there is a big lack of lighting. Help me please diopassane28@yahoo.fr

  • Carlos Ribeiro

    You may be able to find actual instructions on the web if you Google for it. Just to give you a basic idea on how to do it, this is just a regular PET bottle used for soda. For example, it can be a big 2 liter Coke bottle, but any brand will do it. Just fill it with water and a small quantity of bleach, and close the bottle. Make a hole in the ceiling and take care to fix it firmly there with cement or something equally as resistant. Part of it has to stay over the ceiling to "capture" light, so to speak. It will spread an amazing quantity of light inside the room as if it were a lamp. As far as I am concerned this is not patented, and even if it is patented, I'm not sure that they could go after people who are building it for their own personal use.

  • Marcos Silva

    What???!!! Developed by students from the MIT where?? This is used in the country side of Brazil more than 6 or 8 years and was "invented" by locals many, many years ago... This one and others low-tech inventions that really is not that hard to understand and easy to install.

  • Carlos Ribeiro

    I've tweeted about it yesterday. I remember seeing this in local TV in 2003, as I lived in Uberlândia, and I've seen it installed there at the time. Seems like the MIT guys are selecting tech that is easy & appropriate for poor areas and this is one of the ideas, but reading other links referred to in the article, they're not saying that they have invented it.

  • wgreunke

    If the bottles were glass, you would not need the bleach and if they were turned upside down they would last indefinately.  This is a good opportunity for a packaging redsign.  A beverage manufacturer should redesign their bottles so that they can be used in this type of application to minimize leaks and simplify installation   The disrtibution channels are allready in place and you could add instructions to the labeling.

  • Carlos Ribeiro

    Glass bottles are much heavier, and if they fall down, they cause a lot of wreckage with big glass pieces. Glass is also returnable and have more value for the industry after used. Plastic bottles are disposable, and mostly harmless (except for the water's weight).

  • Sanyu Nagenda

    It's certainly a good way to recycle as well. Perhaps we can take all the plastic from the great plastic trash patch and make better use of it! 

  • Ian B

    You probably don't have to go as far as the Pacific Trash Patch to find empty plastic bottles. I just got back from Haiti, and waste plastic bottles are easy to find anywhere.