Light up dark areas in your home during daytime using this green and sustainable concept. Recycle used clear plastic soda bottles, add water+bleach, then install. After installation this solar light bulb can provide approximately 55 watts of light from the sun! 

The comments below have noted that this is like a solar tube or deck prism. 

The communities who benefit from this idea live in areas where the houses hardly have windows and live in darkness even during daytime. Their solution up until this innovation was to turn on the light bulb and use electricity.


*PET soda bottle
*Galvanized Iron (GI) sheet
*Rubber sealant
*Filtered Water
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Step 1: Cut approximately 9 x 10 inches of GI sheet (corrugated or flat)

Picture of Cut approximately 9 x 10 inches of GI sheet (corrugated or flat)
(Filipino: Gumupit ng yero na may sukat na 9 x 10 inches.)

*Here is a how-to video

Step 3: Cut the 1 cm difference radially, making strips and bend upwards, perpendicular to the GI sheet

Picture of Cut the 1 cm difference radially, making strips and bend upwards, perpendicular to the GI sheet
(Filipino: Gupitin paikot ang natira na 1 cm sa maliliit na bahagi at itupi pataas, salungat sa yero.)

Step 4: Using sandpaper, scratch the surface around the upper third portion of the soda bottle where the GI sheet will be placed, to allow the rubber sealant to stick better

Picture of Using sandpaper, scratch the surface around the upper third portion of the soda bottle where the GI sheet will be placed, to allow the rubber sealant to stick better
(Filipino: Gamit ang sandpaper, kuskusin ang ibabaw sa may ikatlong bahagi ng bote kung saan ilalagay ang GI sheet para mas dumikit ang rubber sealant.)

Step 5: Insert the bottle into the GI sheet until the upper third. Apply rubber sealant on the strips above and around the area below. Wait to dry

Picture of Insert the bottle into the GI sheet until the upper third. Apply rubber sealant on the strips above and around the area below. Wait to dry
(Filipino: Ipasok ang bote sa gitnang butas ng yero hanggang sa itaas na ikatlong bahagi. Lagyan ng rubber sealant ang itaas at ibaba ng pinagkabitan.)

Step 6: Fill the soda bottle with filtered water and ~10 mL (2 capfuls) of bleach. Cover with its original cap

Picture of Fill the soda bottle with filtered water and ~10 mL (2 capfuls) of bleach. Cover with its original cap
(Filipino: Punuin ang bote ng filtered na tubig at ~10 mL na bleach (2 sukat gamit ang takip). Ilagay ang takip.)

Step 7: The solar bottle bulb is now ready for installation!

Picture of The solar bottle bulb is now ready for installation!
(Filipino: Ang solar bottle bulb ay handa nang ikabit!)

(Proceed to next step for the installation.)

Step 8: Cut a hole on the roof, similar to the bottle circumference

Picture of Cut a hole on the roof, similar to the bottle circumference
(Filipino: Gumawa ng butas sa bubong, pareho sa sukat ng bote.)

Step 9: -Place the solar bottle bulb into the hole. Make sure it is firmly in place

Picture of -Place the solar bottle bulb into the hole. Make sure it is firmly in place
(Filipino: Ilagay ang solar bottle bulb sa butas. Siguraduhin na maayos ang pagkalagay.)

Step 10: Drill 4 holes on each side of the solar bottle bulb using Bosch lithium-ion cordless drill and put in the rivets

Picture of Drill 4 holes on each side of the solar bottle bulb using Bosch lithium-ion cordless drill and put in the rivets
(Filipino: Magbutas ng apat sa magkabilang gilid ng solar bottle bulb gamit ang Bosch lithium-ion cordless drill at lagyan ng rivets.)

Step 11: Apply rubber sealant around all edges of the GI sheet of the solar bottle bulb to avoid leakage. Make sure to cover the rivets

Picture of Apply rubber sealant around all edges of the GI sheet of the solar bottle bulb to avoid leakage. Make sure to cover the rivets
(Filipino: Maglagay ng rubber sealant sa lahat na gilid ng GI sheet ng solar bottle bulb upang maiwasan ang pagtulo.)

Step 12: Place a protective plastic tube on the bottle cap and apply rubber sealant

(Filipino: Lagyan ng plastic tube at rubber sealant ang takip ng bote.)

can you use it as a amplify for lights???

jopeyemi9 months ago
Great how/where can l get bleach. My email or pls help me


AKHIL JIJO2 months ago

will it work at night

Not without a light source to shine on the bottle, which kind of defeats the purpose

khrope.medo20 days ago
As for the bleach - is it hypochlorous acid or hydrogen peroxide?

The only purpose of the bleach is to keep algae and other fungi from growing in the water over time

rrese10 months ago

whether it will still be lit if I put it in the garden? with poles for example, as a replacement for garden lights?

Choclinda rrese4 months ago

It won't work in the dark.

What will work is a battery operated headlamp around the clear bottle of water. Light facing the water. Try a clear milk jug for even more light. The water "magnifies" the light.

What will work is a battery operated headlamp around the clear bottle of water. Light facing the water. Try a clear milk jug for even more light. The water "magnifies" the light.

mahesh burse4 months ago

will it work at night???????? Upto how much time a bottle will go????? any thoughts.......

It is run by sunshine. If it is dark outside, it won't light your room.

it does not work at night. (unless you got streetlights outside though the resulting lumination would be really dim compared to that of at day) and it only refracts sun light.

I doubt very much that street lights would produce enough light to penetrate the bottle.

Obviously it doesn't work without natural light. It's the light outside that shines through the water in the bottle that creates the light. The bottle will work endlessly unless it's broken.

This is being done in South Africa where it is very successful as there is abundant sunshine.

if it has solar panel and battery, it can be used at night, and even can charger small device like phone ,mp3 etc
optional: remote control, usb port ,
let bring light to life .

solar powered flashing light.jpg细节.jpgsolar led light.jpg
paparod482 months ago
I did what your instrutions are . But doesnr work

It will not work in the dark. It must be sunny outside.

22540521701 month ago
A good way to save electric power
AKHIL JIJO2 months ago

will it work at night

Where can i find a plastic tube? Ive been looking everywhere for something similar to old film containers but havent found anything similar. Any advice?

Buy Coke or Sprite 1.5L.

Buy Coke or Sprite 1.5L.

Buy Coke or Sprite 1.5L.

Are you going to be traveling to Taos soon? I am not sure if I am asking the right person :-)

I don't think you need anyone to travel to Taos. You can simply make it yourself with an empty clear plastic bottle or container.

RE: Choclinda

Lol!! I obviously should have been more specific.

The man who invented this special light technology was to attend a conference here in Taos and I was wondering if the author was the same person. I agree that anyone could make this with this Instructable or a tutorial.

And yes, the man responsible for this technology did in fact speak at the conference and I was lucky enough to see him.

Sorry for any confusion. Which is why I originally had asked if this was in fact the same person.


is it ok not to put it in a bottle?

with no bottle, you just have a hole in the roof, so do NOT skip that step.

what tool did you use to cut the circle on the galvanized iron sheet? (i need to describe it in my research paper) thank you!

Step 2

Clearly shows the hole being cut using tin snips.

Looks like a starter hole was made using a cold chisel(which COULD be used to make the whole cut, but would take a bit longer, and not be as "clean"

Dark Bottle7 months ago

really cool

Excellent!! Now I know how I'm going to light my shed, and I'll certainly be passing this along.

jimbuntu1 year ago
I heard it use a lot in the Philippine.
I saw this link:
Also in Brasil
ksail1 year ago
Nice work
-t2 years ago
I love this idea but I am curious if it could be made more efficient with the use of a Glass bottle and a more reflective piece of sheet metal (like aluminum?).

Any thoughts?
diy_bloke -t1 year ago
It all depends where you want to put the aluminum reflector.
For the amount of light PET or glass does not make much difference. There arent much places where you could put any aluminum. Around the bottle? can but you'd end up with a spot light and not with a light radiating to all sides.

There are commercial light tubes available (at a steep price I may add) that is basically an alu or stainless steel tube that reflects the light at the inside, making it possible to go around an angle a bit
Is there something special about PET bottles? Would normal un-PET bottles work too?
the special thing about them is that they are abundant
Any bottle that is made from UV resistent material would be ok
BlueKnyght1 year ago
can't we use glass bottles instead of pet bottles??? i think glass will last longer than plastic... or probably forever if left undisturbed.
The weight would be prohibitive, plus it would be dangerous if it disconnected and shattered
actually, i've done it. I found a very long 1.5 liter glass bottle from a school sci.lab, and when I got back home, I bored a strategic hole just beside a roof beam/frame, and I attached the solar bottle bulb on the 3" x 6" wooden roof frame for strength, using epoxy, steel wires, and plenty of roof sealant... I think it's strong enough to last.... unless maybe some earthquake breaks the frame it is attached to. Sadly it is only brighter when the sun outside is brighter... and I definitely don't advise looking at it directly when it is bright.
Even with plastic bottles I run a support wire, just to make sure :-)
Glass in principle is possible.

Ofcourse one can always buy a commercial solar tube, from aluminium, at 200-250 euro

J Chance1 year ago
Is the galvanized Iron sheet needed or is that only if you're using it for the roofing?

I'm doing an art piece and I really want the lightbulb affect without the iron-sheet on the bottle.
that is not needed at all. it is just because it is installed on a roof.. Could also make a hole in the roof directly, any roof practically, as long as you make sure it is sealed
good one
verity331 year ago
You may all be interested to know the story of how these bottle lights started:

It's a great story! :o)
Varenberg2 years ago
This may seem like an odd question, but what if you use a bigger bottle, like the 5 liter ones? Would the light distribution become more like a 100 Watts light bulb?
Think of it more like a skylight than a "bulb", A bigger opening would introduce more light, but it would need some sort of additional strapping to support the weight
nmoraga2 years ago
just a question , what if i pour half of bottle with bleach and the other half is water, will it be more brighter?
LNaboo nmoraga1 year ago
no, the bleach is just to keep the water from stagnating
Good Question...
donkeyknee1 year ago
Thats good
sensational and informative! thanks
Thank you so much :) You made my day !!
acachucho2 years ago
Could someone please email pdf instructions as I am not a Pro memeber
kdiane2 years ago
sensational and informative
aewers2 years ago
It isn't anything special just the light being scattered. Kinda like when water drips from a sink and you see little dots of white light flit about the ripples. There is no chemical reaction or luminescence. It only provides light during daylight hours. Hopefully that helps
JensonBut2 years ago
Thank you so much :) You made my day !!

MartijnD2 years ago
I would add some salt and alcohol too, if it freezes the bottle will suffer less forces because the water will not freeze so the water will not turn to ice; ice has a lower density than water so the volume will go up, stress on bottle where the bottle is in contact with the roof-panels.

Adding fluorescent components wiil make it glow a little, not enough to see what you would be doing but maybe nice as an orientation light.

These kind of bottle lights can also be placed in a wall, I saw it in one of the Transformer movies near the Pyramids where megan and shia hide and are found by a bug-transformer, these look more like glass wine bottles glued in a cement wall, looks pretty cool too!
MartijnD2 years ago
I would add some salt and alcohol too, if it freezes the bottle will suffer less forces because the water will not freeze which results in ice; ice has a lower density than water so the volume will go up, stress on bottle where the bottle is inside the roof-panels. Adding fluorescent components wiil make it glow a little, not enough to see what you would be doing but maybe nice as an orientation light. These kind of bottle lights can also be placed in a wall, I saw it in one of the Transformer movies near the Pyramids where megan and shia hide and are found by a bug-transformer, these look more like glass wine bottles glued in a cement wall, looks pretty cool too!
jniedo2 years ago
Cosmic Electricity
ggarriga2 years ago
There are several comments on the use of Glass Vs PET bottles. As I see it your only issue would be with weight of the container and the strength of the adhesive used to fix the bottle to the roof/ceiling; Maybe using smaller PET bottles 1.5 liter/600ml in larger quantities a beter distribution of light can be achieved.
msluka2 years ago
..tolle Geschichte!
fretted2 years ago
Hmm the Bleach keeps the water from stagnet nasty's and the water refracts the light from above to below into the darkness very clever nice Ible
thank you, how many grams should be added to how many ml of water to make this as we dont get chlorine liquidised.
-t2 years ago
I am building a houseboat utilizing upcycling techniques and DIY energy harvesting. I love this idea! but I am curious if it would be more efficient with a glass bottle and a more reflective metal (like aluminum).

Any thoughts?
kmasoods2 years ago
Great idea...
But i want to clarify somethings.... One.. what if i at some part of the day I dont want the light to be there in the room... How can the light be removed temporarily...

Probably some kind of cover would be the best way to block the light with out leaving a big hole in the ceiling.
nmaynite2 years ago
hi...this is thine from BSYF (Bagong Silangan Youth Federation)...we went der yesterday po with Asian Bridge Phil and Asian Bridge Korea.... i/we reli lern alot from your foundation..... AJA!
davidkichi2 years ago
Great instructable! Not to be silly, but I don't think anyone has addressed the issue with the sun heating the water in which could be used if the container was perhaps bigger (water cooler size) to hold a certain amount for washing dishes or light showers during the summer. You'd need to have a hose going into the top for refilling with fresh water and a hose or shower attachment on the bottom with a release valve.
I have tried to make a model of this solar bottle bulb for my science exhiibition but I don't know why it is not working... I sealed the bottle properly, used liquid bleach and water but it looks like a simple soda bottle filled with water...need help desperately....plz help..
Well, in actuality they are cheating just a little bit.
While the top and bottom of the bottle sticking out it collects and puts out light at a greater angle than just a hole it does not increase the power of the light. So in normally lighted situations it is just that, a soda bottle with water in it.
Since it is the only source of light for the videos it looks really bright (and the cheating i mention was added exposure and contrast on the video)
that being said, you arent doing anything wrong.

As with most of these feel good initiatives and whatnot, they make them look really grand, but they are often less than grand, or at least rather simple.
Not saying it is a bad idea, it is good, but it is being rather over-marketed.
There's no revenue involved so why take the pains to market it? Even if they were "over-marketing", they need the hype to spread the word and help as many people as possible. You suggest that there is some deceit involved with images and the concept. Everything is enhanced with the technology today so just take it for what it is...something positive.
it your bottle catching any sunlight? It should
friendz........does this work???????? i want to do this 4 my exhibition...
Padre Paul3 years ago
I was wondering does the solar bottle bulb light in the night? I have read all comments with a view of finding an answer to this question in vain.
It does not work at night. The only way it might work at night is if there is a streetlight near by or there is a really bright full moon. All this does is refract the sunlight into the room. The water does not PRODUCE light, only "bends" existing light into the room.
Tazo Padre Paul3 years ago
you've read all comments but you did not read the first line of the instructable itself, you will find the answer there.
akosisamae2 years ago
as far as im concerned, for me this project is good and equip for the people. we can use it in our houses. but like what other commentators are asking, how the bottle full of water with bleach lighted? is it becoz of the reflection and exploration of sunlight.?.. can we use this thing in night ? :) thanks
bfk2 years ago
This is a great new-tech update of glass deck prisms used aboard ships centuries ago. Perfect for sheds. Thanks.
DURANT2 years ago
Is it OK to use this idea in our college research?...
weskeryami2 years ago
hola enserio esta cosa prende? jajaja por q ya lo intente para un proyecto pero no nada q brilla y segui al paso todas las instrucciones .... necesito ayuda ....... porfas...... es urgente !!!!
kaalas2 years ago
can u please say me the reason how it glows?????
Kalaas, have a look at the comment at the top. The bottle doesn't glow it catches the light of the sun and passes that on into the home. Lighting designers would call this a "solar tube" or something like that...
and i have an another doubt. Will produce light at the night time also? because im presenting dis experiment in my college so that we can help d poor!!!!
zszczęsny3 years ago
OK, I've read all the comments and explanations and I still do not understand one thing:

Why the hell can't they use full (unopened) bottle of sparkling mineral water?

This would have the following advantages:

- sparkling mineral water coming from beverage manufacturer is aseptic. High CO2 content kills any algae or bacteria.

- internal pressure of CO2 in the bottle prevents shrinking/swelling form changing atmospheric pressure allowing for good roof seal.

- though actually CO2 can migrate through the wall of plastic bottle, the diffusion factor is pretty low, so it will keep internal pressure for at least two years. Original closure by the manufacturer is also pretty tight and leak-proof.

- no need of bleach or other additives - the price of sparkling water PET bottle at the shop is also very low.
i want to know d reason why it glows???? can you explain me?????
It glows because it catches the light of the sun!
I agree with beehard44. We don't like to waste stuff. So, we'd rather drink the drinkable water then just put in not-so-clean water(ex:tap water) and bleach which does the same thing.
sir, you and zszczsny seem to be missing the point of the project...these pople to who this man is doing this project for are already poor enough as it is...instead of buying the bottle sealed up from some supermarket (in this case probably just a small town outside food market) and all that fancy stuff, he is re-using an initially useless object which would have been cluttering up the streets as litter, OR sitting in a landfill somewhere just chilling out, and turning it into a VALUABLE resource...Light for those who cannot afford electric lighting...or even afford to buy simple candles during the day. A word to you fellows and everyone else in our instructables community...Most all of us have grown up in an environment where we could afford simple luxuries/commodities...apparently this town is one of those in which only the rich can enjoy them. Stop and think about what you write before you write it about why the person is doing a very special and commendable thing for their people. As far as "wasting" water...well, one could easily replace the lost water by digging a hole in the ground throwing a pot in the middle with green folliage around it, secure a plastic sheet with rocks taughtly over the hole and placing a reasonably sized rock in the middle as to not loosen the plastic. is a day or so, you would have already replaced the water that you used up...maby not efficiently, but you still replaced it. I am not in any way trying to be mean nor have an attitude in this message, so if thats the hint you got, thats not what i was trying to do...i am merely implying an emphasis on the matter. sir have inspired me to instead of using electricity to power lights in a treehouse that i am going to build for my children in the near future, i am going to use your idea of the "Soda Bulb" to provide light for them. thank you so much for this valuable method of not only recycling, but also providing light in a way that halps the environment.
Noting the location where this is being done, the cost of an unopened bottle might be a bit too pricey, compared to a discarded bottle that was scavenged from a landfill at no monetary cost. Bleach might also be free to the locals if provided by an NGO aid group, so it's a matter of free materials versus a commercially purchased item that does the same thing.

I agree that using the original would be more stable, but if it was punctured, then you'd have the potentially sticky residue of the drink to deal with too, versus plain water.
Sure - we are talking about poverty what has no limits. But taking into account the movie provided by liwanag - he collected the bottles just "in situ" rather than on the landfill, so I presume somebody from the locals had already drunk the content... I presume saving it from drinking and using it "as it is" for lighting can be actually better saving than struggling with leaks and algae...
Here in the philippines people are very conservative when it comes to food. There's barely any wastage. Which is why we use empty bottles instead of unopened bottles. Why use unopened bottles when you can drink it first and replace it with water with bleach?
Besides, there's no sparkling water here.
tere bin2 years ago
Can any 1 tell me that instead of bleach....if there is any other locally chemical avaible which can make light enter into the space and create a Fascinating space....or there is anyother solution that can make react water to create GLowing and lumincing effect
kaalas tere bin2 years ago
ya fill it with 10ml of chlorine in a fully filled water bottle!!!!!!!!!!! but i want to know how it glows and why??????
(removed by author or community request)
The bleach is used as an anti-bacterial agent.
lululululu3 years ago
Did you think about putting some optical brightener (that we can find in some laundry detergents) in the bottle?
it would for shure increase the luminescence of the bottle...
Remag12343 years ago
Great idea, here's comes the Big BUT.........why not just cut a hole and silicone a piece of Lexan/Glass in place and have the light and not worry about bottles degrading with the possibility of bleach spilling on things below...
Just my 2 cents and what I think is a better way to go GREEN.
I personally would not use bleach. I would use Hydrogen Peroxide as it will do anything that bleach will and it's not harmful to the environment if it happens to leak or get destroyed somehow.
Good Ible !
I don't think hydrogen peroxide would work. The purpose of the bleach, i'm pretty sure, is just to keep stuff from growing in the water. hydrogen peroxide will leave the water pretty quickly and junk will grow in the bottle, whereas the chlorine will keep the water clean. That much chlorine in that much water isn't very bad, you could probably drink it with no problem. In fact people put small amounts of chlorine bleach in containers of water that they put away for emergencies, just so it will be drinkable a year later when they get to it.
think of bleach as two parts - chlorine and soap. The chorine will break down with sunlight (check with anyone with a pool or hot tub) while the soap will last quite a while. BUT, the hydrogen peroxide will leave much sooner and will not leave anything behind to help keep things clean. Also, there is the cost of a little bleach or a lot of the peroxide. Just like the cost of the bottles vs the lexan, bleach makes more sense economically.
My bleach and also Hydrogen Peroxide neither one has dissipated inside a closed bottle. Only when I open them to the air do they go away. As long as the bottle is sealed up, I don't think either one will "go away". I've used them both for different reasons, and have found they both will do about the same jobs.
I use the same amount of one as the other and find no difference between them for getting a job done.
Sorry but the HP is cheaper for Me.
I'm not an engineer, just speaking from experience.
Hydrogen peroxide breaks down under UV exposure (which this would get plenty of). however, chances are the HHO already killed what was in the water and it was sealed, so there shouldn't be anything green in there once the hho breaks down
If you watched the video's you saw the economic situation of the people there. The bottles are free. The portion of the bottle of water above the roof acts as a prism bringing in more light than the same size hole with a plexy glass cover would. The smaller hole in the roof has several advantages, one being less caulking to buy, and no need to add structural support under the tin that a larger hole would need. Also with the corrugated roofs they show a larger flat sheet would be way harder to seal and get so that it would not hold rain water at the top edge.
Bosch cordless drill price.......cheapest I found is $110.00 plus S&H, tax equals to about $140.00. Cheap tin shears cost is about $15.00. Poor indeed.
Have you seen the conditions of the place? The materials (including the tin) they use are scavenged from garbage, plus the drill is probably years old, or is borrowed (I know 'cause some of my relatives live in these places). We Filipinos (especially the ones in the poverty class) tend to keep using the same thing until it quite literally breaks down or until it is absolutely beyond repair.
I doubt any of the "home" owners there owned the tools, as you saw the guys had an assembly line going to make dozens of those. Also had a big water tank, the kind aid agencies use to provide drinking water. I wouldn't be surprised if it was CCF or some similar group doing this to improve living conditions in a shanty town.
The other advantage of the bottle is that it descends into the room and reflects light in all directions, no matter where the sun happens to be striking the top of the bottle. A glazed hole the diameter of a soda bottle would give a fraction of the light, and would not distribute it evenly.
The first I saw of this idea was in the Phillipines in a very, very poor neighborhood. I think recycling a soda bottle is a whole lot greener than paying for Lexan or glass which are probably not available. The great thing about the technique is the metal piece the bottle is inserted into becomes a shingle. Very easy to tuck under where two pieces of wrinkle tin overlap, and the caulking is then minimal. Difficult to seal around a flat piece of Lexan or glass, don't you think?
It occurred to me that if you had Lexan or glass, you'd just build a window the size of the glass. When all you've got is a soda bottle, tin snips, and water, the solar water bottle is an elegant and simple solution.
Alternatively, if cost or availability of Lexan is an issue, you could simply cut open a few bottles into sheets and conform them to the corrugations. A little heat would help to soften the plastic to make this easier.

Downside of this is you lose the lens effect of the bottle.
You big BUT doesn's exists. do you think about the money???
good idea on the lexan. but you got to remember. he basically made it VERY green by the stuff he finds available. , the bottles didnt cost him anything. the lexan on the other hand comes with a price. glass as well. i could make this with no cost to me at all. but with the lexan. if i didnt have it available. like them, ill be without light for a long time.. BUT the lexan/glass idea would let more light in. it would be called a major upgrade in the hood,
also an empty bottle is way cheaper than a sheet of glass
yes and no to that. the water helps distribute the light more evenly, it "scatters" it. glass would simple let down a focused beam (that would change direction based on the time of day) also it uses very little bleach and plastic takes a long time to break down.
velcro23 years ago
It sounds great at first but all of you are forgetting barometric pressure. Plastic bottles make very good barometers and they can shrink and expand according to the barometric air pressure at the time. If you make your plastic bottle light during a time of low atmospheric pressure (i.e., lower than 84 cm) and fill the bottle then when you have high atmospheric pressure the plastic bottle will burst. If you keep the water at a lower level to accommodate this you will still end up with a sealant problem with the roof panel. The bottle will expand and contract and reduce the integrity of the weather seal around the bottle (if there was one to begin with) and it will leak when it rains. The mid-tropics get a disproportionate share of the sun's UV light which also has a detrimental effect of the plastic bottles causing embrittlement and cracking. It's back to the "drawing board" on this idea and perhaps a glass liter bottle (like the old coke bottles) might be more durable and longer lasting. The glass coke a cola bottles were thick and fluted and the shape would allow it to be secured easily in a roof panel.
this problem can be inhibited by submerging the bottle completely when filling, and capping it while submerged. Zero airspace in the container removes the major portion of barometric effects, as water is essentially non compressible.
criggie velcro23 years ago
I understand your point, but then these 1.5 and 2 litre PET bottles would be exploding on supermarket shelves. And I've never seen that.

More likely it would split and burst if the temperature drops to below 0 degrees C.

Personally I think one piece of "laserlight" plastic corrugated instead of a sheet of iron, works much better.
Dr.Bill criggie3 years ago
I've seen them explode right in the store. It seems the combination of carbonated water and the heat in Hawai'i sent the pressures up and BOOM !
big mess

However, I don't see water and chlorine doing the same even with the heat.

Very good idea BTW.
shortw criggie3 years ago
I had those 2 liter bottles outside in sun with soda inside and they become hot to the touch and no explosion.
I also forgot them in the car at -15 C and they froze and there was no damage.
I use a frozen soda bottle of water as a icepack and drink every day for my lunch-box without any problems.
I don't see the barometric pressure as a problem. If the bottle shifts enough to fall out of the hole, run for cover before the hurricane hits.
I believe you're thinking backward, a high barometric pressure would tend to make the bottle collapse rather than expand or "burst". Either way, if you were careful to trap as little air as possible in the bottle the barometric pressure would have little effect on the dimensional stability as the water will not compress as air does. These bottles are basically polycarbonate, AKA Lexan, and are incredibly strong. I have had over 120 PSI of pressure in them with no detectable deformation! I seriously doubt you will get one to burst with a drop in atmospheric pressure, even if you placed it in a vacuum chamber.
keng velcro23 years ago
I think they are ok with this. The research I did when doing a home soda station showed that they will take a little over 200 lbs/square inch.
taliran3 years ago
NICEE.....go a head!
How does this solar bottle work?
Adum243 years ago
Darn it! Of course this guy will win because he has an emotional back story! :)
Best of Luck!
peeps12343 years ago
Let's think on how this is being created.
firstly, I believe that adding bleach produces lots of nascent [O]. Now since there's nothing to react with, nascent [O] reacts with nascent [O] to produces O2. Excess production of O2 leads to O2 gas bubbles in the solution, leading to lots of Total Internal Reflection. Saying Refraction without providing explanation is not really good, in this case.

Adding Ethanol as an anti-coolant or something wouldn't be good since excess of nascent oxygen would oxidise it to carboxylic acid. Which might erode the bottle if concentration is too large.
Also, salt may increase the Refractive Index, but
1)Just TIR at the border of water and plastic or plastic and air will not be enough for such amount of light.
2)Salt also makes it a little translucent.
poppet23 years ago
I haven't seen the answer to whether or not the bottle is apt to freeze...and if there's any way to avoid it. Love the idea, but live in the north. The inside of the shed might be relatively warm, but wouldn't the outside make the whole thing freeze? If it wouldn't freeze, could one be put in the side of a building? That way it wouldn't be covered with snow in winter.
Let's keep it simple. First, this works by refracting sun light (no sun, no light), so any other substance that refracts light may work. The advantage of the water is that it's cheaper than any other liquid. They add chlorine or bleach to prevent the growth of microbes, thus extending the lifespan of the device.
Now, you have two ways to avoid freezing: adding a modifier or replacing the liquid entirely. As we said, it would make it more expensive to use anything different than water, so an additive would be better. Salt is a good idea, but unpractical, because you need a lot of salt to achieve a useful result. For example, to lower the freezing point to -5ºC you need 2% of salt. Also, the more salt you add, the more turbid the solution gets, so it will lower the effectiveness of the device.
I guess the more convenient way to approach the problem would be a mixture of an anti-coolant and water. The best choices, economically speaking, would be ethylene glycol (the common anti-coolant) and ethanol. You would get almost the same amount of anti-cooling effect with mixtures of these substances and water (in a 50:50 mixture, you would get a freezing point of -37ºC with ethylene glycol and -32ºC with ethanol). The more important thing here is that ethylene glycol is more expensive and is poisonous. Ethanol, on the other hand, is cheaper, but flammable (although, the more water in the mixture, the lower the risk).
If you want, you can take a look at this page:
There you'll be able to find the tables with the proportions and the freezing points of ethanol:water mixtures.
One important note: both ethylene glycol and ethanol have preservative properties, so if you use them, there's no need to add bleach or chlorine, specially in the case of ethylene glycol, because the bleach will attack and decompose it.
Hope it helps, see you.
I don't drive so I've never taken a close look at antifreeze, but it seems like the obvious answer. Their could be very obvious (to drivers) reasons it's not suitable of course :)
You could salt the water and lower the freezing point down to 28 deg. I'm not sure about any chemical reaction, but alcohol would lower it even more. Maybe replace the bleach with alcohol. Too much alcohol might speed up the breakdown process. Even better fill it with mineral oil.
A lot of soda bottle manufacturers are adding stuff to the PETG now that causes it to break down in sunlight. Some are even not using PETG. They are using a corn based plastic that will disintegrate over time. I don't have any sources for my info but I remember seeing it on one of the tree-hugger TV channels. I actually think it is a good idea to build in the decomposition. Even though I am anti-green. Hopefully that technology will not make it to your part of the world for a while, so you have good long lasting light source.
how can you be "anti-green". like you want to chop down all the trees you see and destroy the environment?
How about by chopping down the rainforest in order to BBQ the last of an endangered species... Anti-green enough for you? :)
BBQ'd Howler Monkey would be delicious...
"I am anti-green"

Really? You actually think that looking after the environment is a bad thing?

dont have to be a tree-huuger to still be green. Hope for you that you wont need that technology to come to yr part of the world, but in fact it already has, but then called light channels and you pay top dollar for them
liwanag (author)  mr.incredible3 years ago
Thanks for your feedback. Will publish the FAQ in the website soon. For now we are saying this PET bottle can last more than 5 years. You may have to change the water every 5 years.

In any case, since this is a young project, they can just re-install a new bottle for just under $1 as the cost of the raw materials.
mrosales23 years ago
First, I found this to be so interesting, of course the simplicity of this I had to try. From my eager try, I find tap water and bleech left in the light does not illuminate. After rereading, filtered water is used. Hope the refrigerater water will be of use.
It is amazing to me that this has been around and it is the first hearing of it.

I am wondering, is it the sunlight that causes the illlumination?
IMHO - there is no "amazing phenomenon" of light scattering by bleached water. It is just as in case of plain water - bleach is only used to sanitize water against microorganisms what would make it completely opaque in days taking into account tropical circumstances.
Yes you would see the best results when direct sunlight hits the bottle, that is what is being reflected into the room below. If it's overcast or cloudy the results will not be as good.
CrLz3 years ago
Brilliant project!

Would love to see designers get a hold of the basic idea and develop products for home owners.
Linksep CrLz3 years ago
They have, it's called a solar tube or a tube skylight. You can buy one at home improvement centers for well under $200 USD.
beopkik3 years ago
So fantastic IDEA!, Does it works at night with moon light? And does it works with a fluorescent lamp or a incandescent lamp instead of sunlight?
diy_bloke3 years ago
I am sure you could use another drill as well. Or is the Bosch mandatory? :-)
definitely mandatory :P
ok, got to buy a Bosch then. Just to be sure :-)
@diy_bloke & bob.the.devil : guys you don't have to be sarcastic :(

liwanag for sure didn't mean to enforce anybody to use a Bosch brand drill it happens that it was the one he used with this project.
Unfortunately it is difficult to convey mood in a reply in instructables. I cannot speak for Bob, but it was in no way my intention to be sarcastic, just to crack a bit of a joke. I try to make that clear by adding the smiley but obviously that did not have the desired effect.
I surely admire this instructable, just as I admire the initiative and in no way did I want to be sarcastic. It was just an open door that I could not resist kicking in.

Thanks for your explanation bro. I'm also sorry if I reacted differently with the joke you intended to crack. liwanag project was able to help his fellow kababayan in his area who cannot afford to pay/shoulder the high electricity bill in the Philippines. With his iniative they were able to save a lot.
No problem, as said, I also highly value projects like this and in fact will be installing a couple next month in So. Leyte
yeah man same here sorry to have offended you we were just poking a bit of fun at each other/joking around. just a little handy man humor. sorry to have offended.
Awesome, but how is this survival??
great idea but would it freeze in winter ? can't work out if it would or not , but at the least would it not act as a heat sink transferring heat outside ?
in many countries where corrugated tin are use for roofs bare or never gets to freezing point. those dwelling can feel like ovens in the summer. easily blown-away during typhoon/hurricaine season=== other smart problem solvers - please address low-tech solutions for ventilation and colling as well for these dwellings -- AWESOME ligth by the way -- by the way in the titles art work - means "i litre of light" or illumination....
yes isang litrong liwanag = one liter of light / illumination
*Just* did this research the other day, 50/50 water and methyl alcohol (sold as HEET fuel line antifreeze) will remain clear and have a freezing point of -50F.
In the tropics, it will not freeze in winter because they dont have winter, So, we can conclude that this solution is not for everybody, It would not work too well in most of USA for instance, in the form they present here from the Philippines. To take your questiion more as: "Can this simple technology work in cold climates?" There is nothing wrong with using a SIMILAR technology, but it wouldn't be quite this low-tech, and it would cost a little more than a dollar or two. Fiber optics for instance springs to mind. If you want to stick to the liquid medium, you could add some anti-freezing agent like you do in the radiator of your car. You would have some energy loss in the dark periods, and during daylight depending on energy input of the sun and temperature difference inside and outside plus the k-value of the bottle+medium, there could be a balancing point where the loss is bigger than the gain. Without looking further into it, I suspect that if you have to worry about such things as freezing water and loss of heat from your house, you are better off with another form of internal lighting. For poor people in hot climates (and not-so-poor people in the same places for that matter, who wants to conserve energy by using this form of daylight indoor lighitng,) it is a great idea! I wish all involved the best of luck! It is better to light a light, than to complain about the darkness.
thank you to everyone for replying on my question .
It will freeze in the winter with the water bleach mix if where your at gets freezing temps. Google freezing point of bleach to see if adding more would keep it from freezing, or use vodka instead of water ;-) It's clear and won't freeze to at least -10f, a buddy likes his vodka ice cold and keeps it in the deep freeze all the time.

The thin plastic will offer little to no insulation value and water is a good conductor of heat. So yes this will act as a heat sink if used in a heated area.
if you are installing it in a low temp area you can use alcohol instead of bleach (as the bleach is only for bacteria and algae control) just be careful touching it during the winter as liquids below freezing temperature can be very dangerous (like freezing napalm)
Add some salt, or clear car antifreeze
...and if it did transfer heat outside, it would probably be a good thing, considering the (hot) locations in which it would be used.
Exocetid3 years ago
Clever idea, very green.

As someone pointed out, this is just a modern, very green and inexpensive version of a deck prism.

The bottle will degrade, but five years is not bad.

Forget bleach, salt is a better solution (no pun intended) because of less damage if the bottle develops a leak. Besides, salt will improve the index of refraction, giving a slightly better light piping effect.

Finally, a kit of parts that would include a rubber gasket (instead of the sealant, a gasket would make it easy to replace the bottle), rubber protective cap, bag of salt and a template with instructions. Could be distributed by UNESCO or some other organization.
jmays3 Exocetid3 years ago
"The bottle will degrade, but five years is not bad."

Which means it will still outlast any bulb you could buy at the store, including those florescent bulbs that cost an arm and a leg! ;-)
pfred2 jmays33 years ago
Yeah but most burnt out bulbs don't make your roof leak.
Gollocks jmays33 years ago
5 years is great. Even with all the labor. I gotta repaint my deck once a year. (had to oil(natural) it twice a year before i switched to paint).

And I seriously doubt Pepsi and Coke are convinced of veggie-plastics yet.
As it turns out...Coke is using 30% veggi in all their bottles currently. Pepsi, as of March 2011 stated that they "will use" 100% switchgrass in all their future bottles.
Exocetid jmays33 years ago
Thinking of the bottle, I wonder if they tried inverting it and if that would give a better, more diffuse light.
kenicai3 years ago
Thanks for making this happen liwanag. this simple project of yours will definitely be a big help not only to the filipino community but for everybody as well. :) good job! Mabuhay!
hsah3 years ago
What about night, if I want to use it at night, will it help or it can be used only in some specific areas where in day SUN never go
hola, felicitaciones por el invento, esto demuestra que existen maneras verdaderamente sostenibles de generar desarrollo. Vivo en La guajira- Colombia, territorio de la etnia wayuu, comunidad indígena asentada en la frontera Norte, entre Colombia y Venezuela, con una población de mas de 500.000 personas, que viven en zonas rurales con muchas necesidades básicas insatisfechas, entre ellas la electricidad. tengo algunas preguntas respecto a este método de proveer luz de manera ecológica:

el cloro comercial de uso domestico es apropiado para implementarlo en este método???

a pesar de lo obvio tengo la inquietud de saber si la lampara ecológica funciona por las noches???

de que manera podemos replicar este modelo acá entre la población indígena que carece de energía eléctrica y luz???

olvidè decirte algo, es posible que no necesiten la làmina de acero galvanizado, porque no estoy seguro de que aporte màs luz, lo que pasa es que la usan porque es una buena manera de lograr acoplar la botella al techo de las casas con tejas metàlicas, pero creo que podrías hacer una prueba en un techo wayuu (que si mal no recuerdo son de madera)
ude luz tankdo3 years ago
Saludos desde Colombia, para la gente que necesite esta brillante iniciativa pueden contactarnos al siguiente correo electronico:, somos los representantes oficiales para difundir, ejecutar y promover el proyecto un litro de luz por toda Colombia, si alguien conoce población que lo requiera no duden en ponerse en contacto,

saudos a todos,

Camilo Jose Herrera Díaz
Executive Director / Founder
Fundación Un Litro De Luz Colombia
314 430 79 82
Duitama - Boyacá
hola, yo tambièn soy de Colombia, te respondo algunas cosas:
en un video vi que usaban pastillas de cloro (que venden en droguerías a bajo costo) usaban 2 pastillas por cada litro de agua, es decir, 2 por cada "bombillo".

las bombillas dejan de emitir luz cerca de las 6 de la tarde (o la hora a la que baje el sol)

yo creo que lo más "difícil" de conseguir es la lámina de acero galvanizado, pero seguro en lugares de reciclaje se encuentran làminas baratas, las botellas se consiguen fàcil, lo que sì he visto es que utilizan bastante las de 1 litro, no menos que eso, y que la botella es funcional durante 5 años aproximadamente, lo que hace que no tengas que estar cambiando el agua con frecuencia.
Que estès bien.
gracias a los amigos que a bien tuvieron la amabilidad de despejar mis dudas, en cuanto a los techos de lamina galvanizada, que localmente conocemos como laminas de zinc, ¿saben de que manera se puede implementar en techos de lamina de asbesto-cemento (o eternit), y para las viviendas wayuu que tienen techos de palma o cortezas de arboles como el cardón?, supongo que para estos casos toca recurir a la inventiva indigena para poder implementarlos con optimos resultados.
Tenemos un album con las fotos de la instalación en tejas de fibrocemento, también llamadas Asbesto-Cemento, puedes buscarnos en facebook como:
Un Litro De Luz
recuerda que nos puedes contactar para la instalación en la comunidad wayúu,


Camilo j Herrera
Fundación Un Litro De Luz Colombia
314 430 79-82
Para los techos de palma y corteza puedes buscar la forma de ampliar la base de apoyo, puedes coger y unir una estructura de madera a la botella y atornillarla o clavarla a la estructura básica de la vivienda.
Bleach does start breaking down after a year,but, as long as it works....Nice idea!
Add some phosphorescent material and you have a night-light as well :D
Petar923 years ago
Why bleach? :)
My thought would be so algae would not grow in the bottle. Thats the only thing I can think of.
actually algae can grow in sealed water bottles. i use old milk jugs to weigh down the cover and the grow algae unless we out a little soap or bleach in with the the water starts to stink if you don't use bleach or soap
algae needs air to grow
waterworks3 years ago
I have seen this idea a number of years back done in the shanty towns of Brazil , and been trying to promoted it among my peers...
Good is on this network... Maybe we will manage to convince more people to take it on and disseminate the concept further in the field...!!!
anyheck3 years ago
You have invented a plastic and water deck prism.

Nice job. I may put one in my shed that has no electricity.
I'd not heard of deck prisms before, but I've seen a lot of light tubes used in eco-friendly houses.

Which are obviously just a new twist on the old deck prisms. :)
Why not surround the clear plastic container with a (mainly) white plastic bag which should also be readily available. This will act as a light diffuser, possibly giving a more uniform light with less lens-efect rings of light.
sowaishing3 years ago
Can anyone tell me why Bleach + Filtered Water + sunlight can grow light?
i think that the bleach is just there to keep certain organisms from growing and generally to keep the water as clean and pure as possible :)
So, if you want a green tinted light, don't add the bleach... :)
rvogeler3 years ago
Love the idea! Thank you for sharing. For some of our friends out there that have not traveled overseas much, plastic bottles, like ones used here are in GREAT abundance, where electricity is not. This is a very doable project overseas for places that are not advanced. I travel and a lot of work with underprivileged places in India, Myanmar and Nepal. Nepal would have the freezing issue to consider, but the others would be a GREAT place to utilize this little jewel! I can think of many places right now to use it. I am very interested too in try to find a way to "charge it up during the day" so that it can provide some light into the evening. Not sure how to merge the two together, but if someone could come up with something, you would literally be helping thousands that I can teach to do this. Very simple and practical! Thanks again!!!
jotage683 years ago
This idea is not new. Back in 2002, after a long energy blackout, a brazilian mechanic created this to illuminate his workspace and there's even a brazilian government program to use this as an option for poor population. This video is from 2002:
There's another brazilian inventor who used PET bottles with milk package aluminium card to create solar panels to warm water, look at out:
Remag12343 years ago
4 GordyH and others,
I don't want to get into a pissing contest but here goes.
I did watch the video, and the end was particularly interesting. They ask for DONATIONS, I hope you were quick to donate. My motto is Charity begins at Home.
That doesn't seem very nice to me. But maybe that's just me.
No, it wasn't a nice way to say "Hey guys, they are looking for donations. Please do so!" and I damn well hope that said person donated cause I just did! Although the donations were in Philipines Pesos so that means for me, it was 41php per Canadian Dollars (not far off from the US though). I firust through I was sending $25 but it turned out to be $0.61! Oops, made a second donations to fix that :)
I feel this is a place to share with others. And I have enjoyed all that many have been sharing for the good of everyone else. I can not understand why anyone with an attitude of selfish greed is commenting on this site. Apparently this person is a taker not a giver. And that is a shame.
acoleman33 years ago
im rather impressed at the ingenuity. cheers mate!

Comme disait Einstein, l'intelligence n'est rien, seule l'imagination compte...

Bravo, superbe idée.

Oh my good!!!! This is a Perfect Idea !!!
hoobar3 years ago
guys what is the bleach , and where can i get? , and about the selant does the epoxy work? any one reply plz
McNoodle3 years ago
I've seen these in Thailand, they're really cool
jmcmurray3 years ago
yes cause we all have tin roofs :D
jleighton23 years ago
How about mixing in glow in the dark paint (phosphorus compounds)? And using a glass bottle since it wont be replaced. with a can on the lower side I could see this lasting indefinitely and directing enough light to read by at night.

in a more useful application, another researcher found pigments and electrolytes together can create a photovoltaic cell from discarded bottles...
eddiedurfee3 years ago
Brilliant! And such a simple solution. I don't understand why all you people are turning this into rocket science. (Familiarity breeds contempt I guess.)
0_Nvd_03 years ago
Regarding the problem of freezing in winters, fill-in the bottle with crushed glass. It will diffract light. Adding pieces of different colors can make the light more interesting. The air trapped between the pieces will act as a heat insulator but glass pieces can still transfer heat.
gomiboy3 years ago
I love this idea. Any idea how long the bottle will last with the constant exposure to sunlight and weather? I'm concerned that the plastic will break down and fail.
liwanag (author)  gomiboy3 years ago
Thanks for your feedback. We've been told that the bottle and the water inside can last more than 5 years.

After which they can either change the water or just re-install a new bottle for just under $1 (bottle + water + bleach + sealant).
Gordyh liwanag3 years ago

Have you though of cutting aluminum cans apart (for the shinny inside) to make reflectors out of? This would direct light down away from the roof and rafters, which can absorb much of the light that hits them.
poppet23 years ago
Just thought of something else. Can bleach be mixed with rubbing alcohol safely? And what would be the proportions to prevent freezing? Could it replace the bleach entirely?
samchamb3 years ago
Interesting idea . This is basically an appropriate technology implementation of the light tube type products . I presume that clear corrugated sheet is not available at an affordable price .
axiesdad3 years ago
Great "ible. The idea is the same as the deck prisms used in old time sailing ships, but recycling available materials takes it to a new level. Just out of curiosity, in how many languages are you fluent? I am sadly monolingual and envy those who are not.
Gatecrasher3 years ago
Mabuhay Pilipinas!

When I was a Peace Corps volunteer there, I thought this would be a great project after I saw the Brazilian news piece on the Brazilian guy who "invented" this in 2002. Glad to see someone finally decided to make it happen!

This is really cool.
vincent75203 years ago
Simply BRILLIANT !!!!
Jislizard3 years ago
Nice instructable...I have a shed which is crying out for some light.

One question, does the bleach have any optical properties or is it just to stop algae from growing? I know some washing powders have fluorescent chemicals which glow in UV light to make your whites shine brighter and I was wondering if this made any difference.

Bleach is only for algae control.

Your idea of using additive that collects UV and emits in the visible spectrum is very good. You get added useful light and less UV.

beehard443 years ago
Good that you guys had the idea to share it with the 'ibles community!
FYI the reason why it is in Filipino is because it's a project in the Philippines
Is this supposed to double as practice for those practicing Filipino? It's just that I find the use of Filipino in an international website somewhat off, although nothing's wrong with it, at the very least.
micraman3 years ago
WOW THIS IS SOO COOL! So wait, it works by 'filtering' sun light through the bottle and then lighting up the interior, is that it?
slylee3 years ago
Very nice! will be making some very soon
notingkool3 years ago
felicitaciones, una exelentisima idea, muy simple y eficaz. Un invento genial.
Espero que en mi pais surjan proyectos asi.

Congratulations, an excellent idea, very simple and effective. A great invention.
I hope that in my country so projects arise.
rsk115843 years ago
Nice idea had seen this on TV sometime ago,, in news channel, and if am not wrong this will work in daytime only or at night also the charge is there??
ude luz3 years ago
Saludos desde Colombia, para la gente que necesite esta brillante iniciativa pueden contactarnos al siguiente correo electronico:, somos los representantes oficiales para difundir, ejecutar y promover el proyecto un litro de luz por toda Colombia, si alguien conoce población que lo requiera no duden en ponerse en contacto,

saudos a todos,

Camilo Jose Herrera Díaz
Executive Director / Founder
Fundación Un Litro De Luz Colombia
314 430 79 82
Duitama - Boyacá
To answer your question "Randofo", yes. The translation is Tagalog. Quite good translation.
randofo3 years ago
This is a good idea. You should include in your intro what exactly this bulb does for people who are not immediately clear... Also, is that translation Tagalog?
liwanag (author)  randofo3 years ago
Thanks for the feedback! Will include the introduction in a short while.
derte843 years ago
I love lo-tech solutions
ChrysN3 years ago
Nice, simple way to bring light into homes, well done!
aaahotdog3 years ago
Very nice, very practical.
bonjo3 years ago
My Dear friend I like this idea so much and can see how good this is for people in your country! I was in Davao 18 months ago and i saw in the rural part of the country just how much this is needed, Thank you for posting now i can advise my friends i met there how to cut down their electricity bills. Great job ! Great video !
bertus52x113 years ago
I like this very much. Good thinking!!