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Talk about your village ingenuity. (And yes, clearly, it’s only for indoor lighting during the day).

Use a 2-Liter Bottle as a 50 Watt Light Bulb lightbulb hack

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of a dozen books on technology, DIY, and geek culture, including the first book about the web (Mosaic Quick Tour) and the Absolute Beginner’s Guide to Building Robots. He is currently working on a best-of collection of his writing, called Borg Like Me.


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Comments

  1. johncruise.myopenid.com says:

    Those guys in the business of installing skylight/sun-tunnel or selling parts for it are probably hitting their heads in the wall/table/desk right now.

  2. Seamus Dubh says:

    Reminds me of the deck crystals the used to use on Sailboats.

  3. Volkemon says:

    Well, 50 watts! Wow….or….

    The 2 liter bottle in my fridge measured 4″ in diameter.

    Using Pi* r squared for area….

    3.1415926*(2*2)= 12.566 square inches

    to get square feet, divide by 144

    12.566 / 144 = .0873 suare feet

    sunlight is 750 w/sq ft (approx)

    gives 65.45 watts.

    Or about 76% efficiency of a 4″ hole.

    Yes it is watertight, but not a shocking improvement over a glass window.

    With many drawbacks in lifespan.

    To read this one would think that there is an unrealized free light source out there.

    I realize that the math is “ideal conditions”, but sun tunnel installers are not that worried. That is a proven, durable improvement. Many 5-10 year old installs where I work.

    Then again, probably not too many requests for sun tunnel installs in the third world… and many waste bottles. Good use of materials, but not a miracle by any means.

    GREAT use of ‘what ya got’

    1. tuckerch says:

      “Yes it is watertight, but not a shocking improvement over a glass window.”

      A glass window of equal diameter will result in a shaft of sunlight that moves during the day. Light in one spot, darkness elsewhere.

      The water in the bottles refracts the light, essentially spreading it in an equal amount in all directions, as demonstrated in the last scene in the clip when the light is tuned off and the bottles are uncovered.

  4. askvictor says:

    I’ve done a similar thing while hiking. I use 1.25L PET bottles for carrying drinking water (cheap, light, very strong). So I stuck my high-power, but very focussed LED torch in the top of a (partly) filled bottle, suspended it from a rafter in shelter/hut/tree, and voila, instant lamp.

    PET bottles can also be used for sterilizing water – 6 hours in direct sunlight, 48 hours when overcast

  5. Odin84gk says:

    Why do they need the film canister over the lid? They say it is to protect the cap… Is that protection from heating that could warp the lid?

    1. Einstein says:

      The caps of the two liters wont last a year in the sun likely. The film canister was designed to block light so it is there to keep the lids from falling apart. And yes it seems that you can squeeze more light into a tiny 2″ hole through water than you can with a 4″ holed skylight. Also the light is usually directional and direct which causes fading of carpets and walls, but with this bottle version the light is evenly spread. Its a good idea, but modern home builders wouldnt dream of using anything like this. They want you to depend on the grid like everyone else. This builder uses all gas this builder uses all electric, this builder uses both. One might as themselves why we do so few things that make sense and so many that make cents. Why heat or cool your home when just 25 feet underground its always a perfect temp regardless your location on the globe. Why pay for curtains to shut out light then pay for electricity to make light? Why run the fridge in winter, essentially its cold outside, then you heat your home, and then inside your warm home you chill things in your fridge. Put a hole in the wall to the outside with a metal box in it. Insulate the inside but not the outside. Bam, instant free fridge for a season. ETC. Why even have an opaque door on the fridge, so it has to be opened to view the contents? Why not a glass front fridge. Glass is a wonderful insulator as well as being able to see through it to choose before opening. All things that make sense to anyone with a decent IQ.

      1. Timmy Digital says:

        Windows are now recognized as “thermal weak spots” in a house. Up to 15 times more heat is lost or gained through windows as is lost or gained through an equal area of wall space.

        Unprotected, 1/8″ windows can account for up to 25% of heat lost during the winter and of heat gained during the summer. There are ways, however, to increase the energy efficiency of windows.
        con-f1a

        Multiple Glazing -

        One important way to decrease energy loss through windows is to increase the number of panes, or glazings.

        A single-paned, untreated window unit is very energy inefficient. A measurement of its resistance to heat shows that this single paned window has a value of about R-1. A double-paned, untreated unit has a rating of R-2.1, and a triple paned unit has a value of R-3.2.
        con-f1b

        Thus the energy efficiency of a window can be more than tripled by using triple paned instead of single-paned glass. This insulating effect is created by the air spaces found between the panes of the window. These air spaces reduce heat losses and gains through the window.

        Additional panes in the window unit, however, do increase the cost and the weight of the unit.

        Low-E Glass -

        While adding additional panes of untreated glass does increase the energy efficiency of window, putting a special coating on the windows also increases its window insulating capacity.

        One type of specially coated glass is low-e, or low emittance, glass. This treatment is only used on double paned windows and the coating is on a surface that faces the air space.

        Double paned windows with the low-e glaze are 35% more energy efficient than untreated double-paned windows. The R-value of these windows varies from R-2.5 to R-3.5. As the R-values of these windows increase so does the cost.

        Gas-Filled, Low-E Windows -

        Some companies fill the airspace in low-e windows with argon gas instead of air. This gas is safe, inexpensive, and readily available. Argon is used because it is an inert gas that does not transfer heat as well as air.

        Maybe a glass frig door would work but I would still worry about heat loss. I keep a few food items in my attached garage during Seattle’s colder months, mainly salsa or soda/beer. You could even add a cheap Thermometer to make sure you don’t get in the food safety “danger zone”.

  6. Patch says:

    This is nothing new. I remember touring the old wooden sailing ships where they would embed glass prisms in the deck of the ship – flat side on top to walk on, but the light would conduct to the interior and beam out in all directions. This is a wonderful example of using ingenuity to provide real world solutions to global problems without the use of additional technological investment.

  7. Brazil says:

    That is a pc from a Brazilian T.V. … It is amazing what the necessity creates. Big ups to them … instead of crying about it … they fixed it.

  8. Matt says:

    This is a neat idea, but it seems like it wouldn’t work in non tropical climates. Having a direct, water filled connection between the inside and outside of your house is gonna kill the R value of your roof insulation, which will end up costing much more than the amount you save by not having to run lights.

    but definitely something I’ll keep in mind for uninsulated spaces.

  9. Volkemon says:

    @tuckerch -

    Sorry for the lateness of my reply….dont know if anyone is scrolling back this far now…

    My comment was more aimed towards the ” OMG- 50 watts of light ” end of things.

    The solar tubes definetly do not have the ‘dot of light’ effect, using a diffuser on the end. Such an item could be employed with a glass pane, and I would imagine it might reduce the efficiency like the bottle does too.

    BUT, to be fair, this bottle idea is still a great use of what is available.

  10. drew says:

    What does the bleach do?

    1. Bruce says:

      Bleach will keep algae from growing in the water. It may also add a low level of fluoresence.

      1. stonefisk says:

        Bleach turns back to safe salt water in sunlight after only a few hours! That’s why bleach comes in dark bottles. It will sterilise the water in these light bottles just the once before UV turns it back to salt water, it doesn’t ‘keep algae from growing in the water’, it is just that the water should remain fairly sterile if sealed.

  11. Anonymous says:

    Do these produce any heat? How much if any?

  12. Anonymous says:

    I understand how the bottle and water makes “light”, but how are they installed.
    The example he showed looked like it’s pushed through a hole in the roof, what
    about sealing water leaks?

    Love this idea, would like to use it in my tool shed here in Oklahoma. Also
    what about freezing temps?

  13. Joy Harmon says:

    Do you have to keep watch on it and refill it?….I guess trips to the roof in some places is common and not so dangerous…it seems so simple…why didn’t I think of that???  Too busy on Facebook lol

  14. Roger Pilon says:

    One more solution for improving the planet. Simple! So simple I am just wondering how many others ideas like these are sleeping in the human collective brain!  There is another solution for the night to get light. Not as much low teck as the pet light idea but…Have a look at: http://theplanetfixer.org/162/light-up-the-world-with-this-solar-powered-solid-state-lighting-system/. Roger Pilon, Editor

  15. Roger Pilon says:

    One more solution for improving the planet. Simple! So simple I am just wondering how many others ideas like these are sleeping in the human collective brain!  There is another solution for the night to get light. Not as much low teck as the pet light idea but…Have a look at: http://theplanetfixer.org/162/light-up-the-world-with-this-solar-powered-solid-state-lighting-system/. Roger Pilon, Editor

  16. Maybe he can use battery operated lights at night. Or generators.
    Or create a device that uses fire in order to create lights for the midnight shift.
    Then he could possible due away with the use of electricity totally.


  17. This is a post from youtube on how to make glow in the dark water.
    I wonder how well you can see from glow in the dark masses.
    And how many does it take in order to light a whole room.

  18. need detailed procedure on how to do thanks

  19. cassandra says:

    Is it possible to fix these in modern houses?

  20. ranjit says:

    the bottles should move with light , this system is nothing but a pin hole camera