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This was done in Philippines. Water and bleach in bottle of coke was fitted on the roof. It absorbs and reflects sunlight and is equal to 55 watt..
More at : +Interesting Engineering
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They also work in between bricks at different levels in the wall structure!
I've seen these before and on first thought they seem very good, but plastic bottles deteriorate in UV sunlight, and now these people have a big hole in their otherwise contiguous roofs. Even if a glass bottle were used, which would be much better, that hole is going to leak sooner or later.
Gavin Bisesi
+Bill DeWitt plastic bottles are plentiful. It can just be replaced. If you'd seen the video of people talking about this in the villages where it's been put out you'd find that people are ecstatic because their other options were to either be in the dark or use unsafe/expensive consumable fuels.
+Bill DeWitt sealing this thing off shouldn't be a problem.. Even the propeller shaft of a marine diesel propelled ship is sealed of water inrush..!
Until the plastic cracks. Three years in the sun and a strong wind can break it. And the shaft of a propeller is multipli-sealed with high quality machined parts. Even so you get leaks there. 
+Fariborz Soroush 
کاکا  سلام
شما که مهندسین بوگین این چیکا کرده من نمی فمم
haa.. hold your horses buddy.. we can make it a sort of temporary water tight fixtures.. like encircling bottles with outside threaded rings and packing . when it goes off.. unscrew,prepare and put another..
Glass bottles instead of plastic, put in under an eaves or ridge but still exposed to the sun, would prevent most of the problem. But roof lights are always a problem, even skylights in developed countries require continuous maintenance. The number of holes in a roof (or a hull) should always be minimized.
ya that seems right for the moment..!
I guess your opinion that it's cool looking excuses loading down people who already have problems with more problems. That's alright, those problems won't show up until after you have shifted your attention elsewhere. Fine, you guys must be right, 20 years of fixing holes in roofs doesn't allow me to point out any doubts. Go ahead and insult me all you want, it doesn't change the facts.
There's different sets of concerns between first world building and elsewhere.
maybe you could utilize in a different way than placing in main roof...perhaps a room within a structure could be designed with a two-tiered roof placement. By this I suppose I mean the main roof stays As Is for insulation/energy consumption purposes...a gap would separate main structural roof from the interior room's ceiling. The gap would allow lighting to be placed on underside of main roof, while Coke bottles to be placed in interior room's ceiling. This idea isn't so much about alternative energy but rather mood and ambiance ( room psychology if you will ). To put into practical example : Underside of main roof above the individual room ceiling ( gap i described earlier) has red & blue lighting which is absorbed and reflected by Coke bottles placed in room ceiling to give off a certain aura or energy. Some may view this as a silly idea but perception is all we have!
+Venus little از شفافیت آب و پخش کنندگی نور توی اون استفاده کرده برای روشن کردن یه اتاقک بدون برق و با استفاده از نور آب.
یه کار بیخود دیگه:))
فک کردم می تونم تو کمچانیآرزوها بذارمش یکی از گوزینه ها
مرسی کاکای مهندس خودم
آخه فقط وقتی روزای آفتابی داشته باشی جواب میده....بعدشم اتاق باید کامل تاریک باشه تا این اثرش رو نشون بده:)
مرسی آبجی کوچیکه.:))
I saw the video about this a while back, brilliant idea for third world countries and creates a job for those in poverty.
I have to admit, I'm going to have to try this.  But I'll skip putting a hole in the roof.
I just recently studied that the Egyptians Found out how to create light in the process of building the pyramids, NATURAL resources for Light and energy has been around much longer than they want to tell us about.
I'd imagine the bleach keeps the water clear and free of bacteria and other waterborne light hogs. Also the the 3rd photo looks so much more washed out because the bottle is the brightest thing in the room and so it got washed out. Just like how you can take a picture of a lit light-bulb close up in detail but in a non-closeup picture it's all washed out.
+Bill DeWitt  What if they had a con of glass or plastic on the roof fixed with silicon at the top of the bottle from the out side?
The Bleach sterilizes the water, ensuring no algae forms, which allows the maximum amount of light to be refracted into the structure. Given the lack of resources in some parts of SE Asia, this is a very low cost alternative to light tunnels which use chrome / reflective light materials on ducts, which are used throughout North America and Europe.
waooooo amaging............
very easy but everyone cann't think about it....
Some buildings are dark during the day if the electric lights are off.
the old sailboats have been doing that for years but with a pyramid shaped chunk of glass.  Brought in light to the dark interior of boats, nothing new.
Oh great,now they've got a hole in their roof!
if that is real that is really cool!!!
Do they not have windows or something?
Oh great,now they've got a hole in their roof!
Awesome! I wonder how bright the bleach water bottle glows at night?
filipino.are really. .REALLY!!! genius. .:-P
+jeff ross Putting a piece of glass there is almost no difference that not have the glass there at all.  the bottle disperses the light in many more directions much like a light bulb. It's pretty clever if you ask me.
Of course, rain and cloudy days could have an effect...
+Joe Page, the point was that most impoverished Filipino houses have no windows or interior lighting.  The inside of the homes was as dark as night 24 hours a day.  This way, they could at least have light in the house during the day for next to no cost.

Your attitude suggests to me that you've got a better idea that you're withholding from us.  Please share.  If you don't, please shut up.
Sunlight? Nope, don't remember that one.
+Orrian Cheatom I can't find a cheap manufacturer online but I think for about $10 USD you can make a solar rechargeable waterproof light that will run throughout the night when the sun goes down. The light output won't be the same but it'd be decent for a garage, car port or, shed.

Edit: Actually the circuit would have two paths. The charge path would be solar cell to voltage regulator to batter. The light path would be the battery to an infrared "off" diode to  to waterproof light.
well if it will take 3 years before the plastic bottle deteriorates at least you get to have 3 years of free light, and then after 3 years just do the process again then again... 3 years is better than nothing, don't you think?
I'd utilize it for my goat pen
No serious engineer would suggest that. It's just a hole in the roof, if you live in a place like that and want light during the day, open the door or go outside, but don't put a hole in the roof. FFS.
dang good Idea, can it be harnised to run more than just one room.
I'm amazed that you seem worried about holes in the roof. These are not western style houses with plumbing, electricity and roof tiles! The windows are closed in the day to keep the interior as cool as possible. Also in the heat and humidity things dry out pretty easily. Spend a bit of time thinking how you educated westerners could improve upon the idea.
+Bob Marshall I don't think there has yet been a more ignorant comment than yours.
بابا خدایی دمتون گرم !!! عجب خلاقیتی!!
کلا هنر کردین خیلی هم با حال
Lol, its like the solar power flash light. Pointless.
thats where the meaning of the word "GHETTO" comes in,Getting,Higher,Education,To,Teach,Others.Big up to the inventor 
+John Weisz ...most of the Filipinos who use this kind of method are informal settler's.. .they live under bridge's ....we're source of light is very limited...that's why,just to survive in this kind of location...they invented this thing.
Thats i called useful thing, and you dont pay anything, 
Kody Wu
Idea is great except for the part where you need sunlight
Too bad it. Only works when the sun is out!

It's clever, but how many of these people need light at midday?

I wonder if there is some solar panel optimization thing there, since you could increase the effective surface area that is receiving sunlight/energy?
Omg that's amazing how did they think of it
Technically, it does not "absorb sunlight".
It's merely a diffuser or conduit of light.
+John Stock Dude, the people who have this are poor - like poor as in can't pay for electricity. They really wouldn't care if it only works during the day as long as they don't have to light up candles during the day as well to see through a dark room. 
Saul R.
What is the water/bleach ratio?
Wonder if this works of the same principle that makes the "Mountain Dew Lantern" work
+Henri Huang Just enough to keep the water in the bottle from growing algae, 1/2 ounce to a bottle or so.
Eric A
Poking holes in my roof today!
+John Stock pointless? I take it you have never needed light inside your home during the day time. Man your lucky. 
+MOHAMED SHAFI, the real reason for the beach is simply to keep the water clear by killing off any bacteria or mold that would result from leftover soda residue.
w nocy ta świetlówka działa? ;)
No threat to GE !!@@!!
what's the significance of the bleach?  just imagine it slipping and falling on someone's head....ugh....
cool this is awesome
Night is night, it works only with the sun outside, I think.
I use this trick when working with high wattage LEDs that have narrow fields of vision. :)
+Raquel Van de Venter Chlorine is in the halogen group, but the bleach is not being used in this case to generate light, so that fact is irrelevant.

I've seen this before- old news. 

+Don Perkins Generally speaking, no. Solar performance works best with direct sunlight, not refracted. 
Water Concerns : For those folks concerned about the hole in the ceiling. I would chill out. To me, even if it did leak, rain water is fresh water. You could collect it and get yourself an easy source of drinking water. Probably healthier than any drinking water these folks might be having.

No Light At Night : For those of you concerned that you won't have light at night. Again, chill out. These folks don't have light during the day or night. So solving 50% of your overall problem is a good first step.

It will wear down : For those of you concerned about the bottle deteriorating. Relax. This is no different than a bulb goes out in your house. They simply replace and move on. 
Just for fun i'll make one at my garage work shop to see if it really works!
Xiomi F
The night is the next challenge. 
People in third world countries rarely look at the long term. They are more concerned with their immediate future. This is a temporary fix because the alternative for them is just not realistically reachable. Considering their location and income.
Don't believe it. The exterior (above the roof) area of the bottle collecting the light is too small to give that amount of light...   :(
finally, electricity is still more expensive :)
Hope you tried the protocol Gabriel,I bet it might work! 
+Sonny J probably every night - but it comes on again in the morning.
That's an interesting invention and quite cheap to install. That would definitely come in handy in third world countries.
have you guys ever been to the philippines it's sad and i know cuz we went there and were moving there ooh did you guys hear about the phone? it's a camera and a phone to gether when you take pix you go  on the web and post it on the web it's about 20,000 peso but in the  U.S it's about $500 dollars no lie
That's pretty neat, I just need to start drilling holes in my roof to put some coke bottles in it. +Erik Sterk 
Imo if ur using a plastic bottle filled w water and bleach to light ur house insulation is the least of ut worries! I think it'svery smart yet simple and will get the attention of environmentalist and companies looking for new ways to use resources we already have like water. Pretty cool huh?
nice job! that bottle could help save energy and this way just turn the lights at night ..greetings from huatabampo, sonora, mexico
Maybe interlocked hollow glass wall blocks so the water mix can be run through and drained as needed. Then you can fit it vertically and horizontally.
Thats too cool! What's the ratio of water to bleach?
I believe we shouldn't be based on few, pre-defined, renewable energy sources, thus a motivation to new and simple energy capabilities helping every one especially people in poverty.
Have you seen their roof. Whats one more hole?
just make it and post it to me man if u know how to make
Great idea, what happens when it rains!
Men I'll just make a protocol,involving a model roof cause I don't want to freak myself! 
2 liter bottle in hole in roof = 55W < Direct Sunlight
AKA zero plumbing, zero fixture, eco-shower
Patrick just believe in your self and no matter where you are you can do great things!
they did the same in Brazil to get some light in house with no window
Hahahaha I knew this before..
I had shared it a long time ago but the source is dead (BBC article) I guess I'll re-share it again.
I want to try it but I don't think it'll be super if I cut a hole in my roof. 
Maybe for a shack in the bush or something, or would be good for third world countries where the power goes out multiple times a day.
   Not the best idea for any house with insulation in your roof.  If you are using a 2x6 to build your roof it would be ok (which would never pass any building inspection anywhere in the modern world) but if you use roof trusses, even a 20' wide house will be 20" from shingles to ceiling at 5' from the wall, and would be 40" in the middle of the house. We use solatubes, or similar products here to get same green results.
For the bottom right pic, the photographer must have lined the sun, the bottle and camera up in a straight line to get that much light. The bleach is only to keep the water clean and clear.
wow their smarter than most of the trolls on the internet.
Ryan P
you just need a bunch of these
good work
keep going
best of luck
Lightning bugs in the bottle at night maybe? hehehe
Simply brilliant. Why has this just now been discovered. That darn lightbulb industry! ;-)
Nice new way help some people save energy 
The most amazing thing after this idea, is the sheer amount of ignorance on display from those rabbiting on about windows, using a sheet of glass instead, and asking why it saves electricity... Hilarious.
Does it work with a Pepsi bottle?
Jah thats a very smart invention...wel discovery i should say.
i like but i cant try it at home... :(
There is a whole program going on in I think it was the slums of Manila, to bring this kind of light to the poor guys there. A famous Phillipine actor is funding it.  
Jay A
that's true. I've seen I that in person lastbtime I went there.
we should do that instead of buying light bulbs
wow that's amazing.!!!!!!!!!!!!!!!!!!!!!!!!!!
only works during the daytime - but good for houses with no windows i guess.
That is a good solution for your garage or shade.
Fantastic what if I use hundreds of bottles

haha this is crazy
There's more engineering that the goverment need to put a lot af attention and budget. 
+jeff ross You see it with an ignorant and entitled point of view.  Having never been there, you haven't seen shit.  I've been to the shantytowns outside of Manila and Cebu City, where my mother grew up.  These people live in a poverty that you cannot hope to imagine as you sit and expand your waistline, gorging yourself on fast food and TV.

This man has created a way of providing daylight in windowless structures using commonly available materials, and he's doing it for free.  Homes that were previously unusable during the day due to darkness can now be utilized.  What have you done to improve the lives of the poor?
I'm glad to see there are more positive comments than negative ones. I feel sorry for those people who have nothing but negative comments, for it shows their lack of imagination. Just an example of what you can do with this. Since it absorbs and reflects light, you can use it to concentrate light to solar cells if you want to charge your devices when camping in overcast days. It's sad to see first world arrogance leading to negative comments. Have the decency to be happy for those people who thought of it. 
+Queen Nefertiti, then the house goes as dark as it would have been during the day without the simple, free installation.
wow, 55, amazing. could yo do that in the USA? that would help out electricity bills. :)
Apaan tuh,,,gambar yg ta dapat q mengerti,,andaikan ad penjelasaan dari gambar tersbut,mungkin akan lebih menarik,,,tp its oke,,,

I honestly don't understand why posts that were trending five months ago are trending again...and a better question is, why do the people even repost them in the first place?
+Boogles Johnson To keep algae and other things from growing in the water that the bottle is filled with.
+Douglas Girardot Exactly. I keep seeing the same Interesting Engineering posts show up at the top of the "What's Hot List". The instant brick road machine should be working its way up to the top again any minute now. LOL.
I will try to come up with a better idea without using google before I say that this one is useless...
+chris louise Try to imagine that how dark a steel shack with no windows and no electricity would be.  Now imagine that you don't have money as well.  Using materials you can find on the street and an hour or so of work, you can have light in your house during the day.  That is far from useless.
Read my first comment again before you say something how's that ??
Not as good as the mountain dew light!!!!

This really helps the resale value of your home. Just tell the buyer that you're going "Green!"
I've lived through 2 devastating hurricanes here in Hawaii with no power. What did we do when it got dark? Sleep! Some of you b!tching about not being able to use this method at night obviously don't live in a poor 3rd world country or experienced a lengthy power outage via major disaster.
that's crazy!! im going to put that in my Canadian home! :)
i think Nigeria's would find this useful...
We can use this simple bottles to light up in homes where sun light is plenty !!!
That's neat, preppers could use that idea.
This is initiative at its greatest!
holy cow! now that is what I call AWESOME!!
I saw that in a documentary about Rio de Janeiro. Quite a nice, simple and effective idea.
Glass would retain more longevity and the roof could easily be sealed using a 3 course method of application using roofing tar and web. I entertain any thought that can resolve energy consumption.
I love coal and I love fracking and I love this 
You should see the lifestyle of those people before you say any bad comment.. For those who can afford to pay electric bill of course they will not apply this but for those less fortunate this is awesome and very helpful.. Good job pinoys!
Many house in the philippines are already using this solar power light bottle. :-)
When it starts to leak... Bonus, fresh water :)
more people should b knpw about it 
At night, of course yuo dont have light. Its sun dependent.
Very green, very cute - this is proper recycling!
Instead of just a picture, how about an explanation...
Very cool, can I have the exact amount or quemical composition.
How about bottoms of glass coke bottles mortared into the wall so the sun shines through? Leak.... Solved light.... Solved and you can use different colors to make mosaics lol 
A few people are quoting a three-year life for bottle vs sun, but doesn't the bleach attack this type of plastic and greatly speed the aging process?
But lights are really only needed when it's dark outside. :/
It seem that this could help 3rd world countries---but a lot of the people carnt afford the bottle---back to the drawing board
+Susan Hawley bottles are just thrown away after the contents are consumed. The bottles are free...
Hey Bill DeWitt, you don't get it! The thing is, its cheap.. no electric bill...

Garden solar lights harness the sun light throughout the day then release it at night or in a dark area! There cheap so maybe just drink the water and clean with bleach?
Wow great.. Maybe i can try built 1
great idea!proud to be Filipino.This thing maybe funny for others, but for them who need to feed themselves first considered this as one of their fortune.Fortunate to have lights in their uncomfortable places.This maybe temporary because being a true Filipino, we are very much eager to learn & do things that can make our lives better, but of course in an honest ways...This post maybe helpful for others also.
1. Who needs lamp in daylight? Why don't make windows instead?
2. When it is raining, possibility of leaking is very high without proper sealing around the bottle.

But anyway, keep up the good ideas! :)
But it doesn't work at night...
+Bill DeWitt the advantage of sunlight outweigh the problem of the holes... and they can seal the holes
Can u magnify l.e.d.'s and run with batteries
Enhanced skylight - how cleaver.  Kudos.
this is a sun and moon powered light bulb & over 3M from slum were benefited w/ this...
If you have one bright LED light bulb surrounded by a bunch of fiber optic cables you could string those cables to different areas of the house and have them shine the light out the other side into all sorts of things, say a bottle of water, and you could then have a bright light in every room of your house; all running on a few watts of energy that one single LED light bulb uses.. If you wanted to turn the light off in one room you could have a switch that flips a sliding plate in front of the fiber optic cable cutting off the light from shining into the bottle or whatever.. In the day time you could quite possibly use the sun instead of a LED bulb to shine light into the fiber optic cables.
A candle can help too...
That's a great idea, but a day-time only kind of thing..
Sol ( shit outta luck)
Unfair distribution of wealth, just like in other countries, few are rich, some in the middle but most are poor.This people may opt getting this trash into useful one for they can't afford to buy something. But, don't get me wrong, because they are the one who can stand most in time of calamity for they can start their lives w/out nothing. So you people don't feel bitter if you know you can do it better.
Indians used fire for light at night... and traded what they gathered.
How long will the chemicals last ?
Fantastic share +Interesting Engineering this could come in handy for several of the areas in Africa we want to return to.

Will have to go and buy some bleach to check it out.
Let there be light! Fantastic share that will create light :-))
People are amazing when it comes to their imagination and their ability to create new things :)
At night it becomes a black light.
Fantastic share *:-)) ♥ ♥ ♥ :-))   (。◕‿◕。)   :-)) ♥ ♥ ♥ :-  
Nice new d s cover
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