Introduction: Aluminum Can Solar Heater

Picture of Aluminum Can Solar Heater

This is how I made an aluminum can solar heater!

Step 1: Save Cans

Pop cans, beer cans, sparkling water cans, any aluminum cans you can save, save them!

Step 2: Gather Supplies

Once you have a bunch of aluminum cans saved, gather these supplies:

Black spray paint (high heat) mine was for grills.

High heat caulk/glue

wood ( I used 1x4's), and a piece of 1/4" thick plywood for the back

foam board insulation, or other foam/insulation


Wood screws

Glass panel, plexiglass, or tempered glass panel

Step 3: Drill Holes in Cans

Picture of Drill Holes in Cans

Please be very careful with this step!!!

Take all of the pop tabs off of the cans, rinse any leftover soda or liquid out of the cans and let them dry.

CAREFULLY drill holes (I drilled 3 holes in the bottom of each can, with the largest drill bit I had). This is to let air pass through the cans.

I just tried to hold the can steady and drilled with a bit of pressure to prevent the can from going flying.

Step 4: Assembly

Picture of Assembly

Once you have holes drilled in all of your cans, you can begin stacking them on top of each other and securing with high heat caulk or glue.

*You can add as many rows of cans as you like, as long as they fit in the "box" you will be building.

I determined my "box" size by a piece of tempered glass that I had left over from an old T.v. stand. It was 24" x 42".

I had a scrap piece of plywood about 1/4" thick that I used for the back of the box. I then just cut my 1x4's to fit around the edge of the plywood making a frame, slightly larger than the piece of glass.

Note: * You can use regular glass, tempered glass, or even plexiglass as long as the sun is able to shine through it and it is thick enough to keep the heat in.

Take a piece of foam board insulation ( I had mine laying around from the previous owners of our house, I also used some parts of a pool noodle), and cut to size to fit around the back and sides of your box. Use your high heat caulk to seal all holes and edges. When dry use your high heat matte black spray paint to spray the foam insulation.

Next I took another 1x4 board and using a large hole drill bit, mine was 1.5inches, drill holes in the middle of the board for as many rows of cans that you have. For example, if you have 5 rows of cans, you would drill 5 holes in the middle of your board. Attach this board (I used wood screws) horizontally about 3 inches from the bottom of your box. Caulk all edges and/or gaps. We want this to be air-tight!

Then, I used the same drill bit to make a larger hole in the middle of the bottom board of my box ( see photos). I did this by overlapping the holes made by my 1.5 inch drill bit. This is to let more air in. I repeated the process for the top board of my box. This is to let the air out. (More on this in a minute!)

Now you can add your rows of cans. Simply line them up matching the holes in your board that you just drilled holes in and use high heat caulk or glue to secure in place. I added some extra caulk to the backs of the cans to help them stay stable. Now you can spray paint everything in your box with the high heat matte black spray paint. Try to get around all the corners and nooks and crannies.

Once dry you can use your high heat glue to attach your glass to the top of the box. Make sure to make a good seal. Again, we want this to be air-tight!

* Since the tempered glass was so heavy, I had to reinforce it by tying a fitness band around it to keep it in place. If I were to do it again, I would use plexiglass or make a recessed box to hold the glass in place better. It did end up working very well though!

Step 5: How It Works & Try It Out!

Picture of How It Works & Try It Out!

*How it works:

When you set the solar heater out in the sun, even on a cool day it can heat up to 160 degrees or so. My solar heater was only out in the sun for a few minutes before it started to really heat up. It was fun to watch and measure the heat as well. I used a meat thermometer to measure the temperature of mine. It was only about 50 degrees outside as well.

When cool air enters the hole in the bottom of the box it is warmed by the black cans and glass, that have been absorbing the sun's heat. The matte black paint is dark so it attracts the sun's rays. The holes in the cans create a turbine effect that spins the air around in the cans as it passes through each can. Warm air rises naturally, so as the air passes through each can, it gets a little bit warner. Finally as air exits out the top hole of the box, and you can feel the warmth!

*Note: Make sure the box is tilted a bit (I leaned mine on a chair), so that the cool air can enter from the bottom of the box.

Also, make sure your box is facing the sun ; )


Wapata (author)2018-01-05

Hi !
What do you heat with that ?

Njturner84 (author)2017-01-19

I'm not sure who would go through the hassle of bringing this in and out of their house 100 times a day to reheat it. I imagine all that extra opening of your front door would defeat the purpose too. And i especially have no plans of putting holes through my house to run ducting. For those in the same shoes... I have seen this done before where you just mount the box in a window in your home that gets a lot of sunlight during the day. Even build a couple and put them in different Windows on different sides of the house

bmurphy21 (author)Njturner842018-01-04

The heat is usually piped in from the outside, they aren't supposed to store heat, just generate it. As for putting them inside a window, a simple piece of black metal or plastic inside the window would attract heat and the cans wouldn't be required. Homes can be designed with walls and floors of concrete or similar materials, often tiled or coloured in dark colours. If you search passive solar design you can find out more about this. I can't seem to paste the link into Wikipedia.

Yonatan24 (author)Njturner842017-01-23

Build a base that tracks the sun, and moves it accordingly.

sgbotsford (author)Yonatan242017-12-28

Not worth it, unless you are really constrained for space. Just build more of them.

sgbotsford (author)Njturner842017-12-28

You don't drag it in and out. Typically you mount them against the foundation, and run a pair of ducts into the house. See for lots more info on this sort of project.

msuzym (author)2018-01-04

Why can’t you just install this on the inside of a window. Wouldn’t it just heat the inside air?

jtharp1 (author)2018-01-03

Very nice. I built one but it took a long time to drill the cans (it was 4'X8"). when I rebuilt it, I used gutter downspout instead of cans. No drilling and just cut to length. It works very well to heat my garage.

crazypj (author)2017-12-30

I think a couple of people missed the point. As far as I can tell the main expense was the black paint? Everything else recycled so I guess main reason for Instructable is to show what can be done without spending ton of cash? You also get some practical stuff out of it. From experience I can tell you, using a 'step drill' (the 'Christmas tree' shaped cutters) makes drilling very thin material much easier than a regular drill and for aluminium cans, the cheapest one you can get hold of will work fine.

stad168 (author)2017-01-17

Have you ever thought about using the same concept but running a hose through the cans to create a color hot water heater for a pool? Do you think it would work?

justin.jackson (author)stad1682017-02-01

Thats actually a method that has been around for years. Someone mentioned it in a comment above, but I also remember my dad talking about doing it in the 70's. Certainly, you could do it with cans but the go to method is to use black PVC pipe. You pretty much just divert the water leaving the pool pump and run it through the PVC which has been laid somewhere where it can get plenty of sun, usually the roof, then tie it back into the outflow from the pool pump. I've heard of it done with the regular white PVC spray painted black because the white is usually cheaper, the problem there is that the black PVC will hold up far longer in the sun due to its UV resistance

My understanding is black pvc is sewage pipe and treated with chemicals when made ???? Not for pool use...

johnt011 (author)Tacticalbaton122017-12-29

If you are worried about too much heat use CPVC which is designed for hot water but it is also a smaller inside diameter.

johnt011 (author)Tacticalbaton122017-12-29

Black PVC is also very large and is certainly Not conducive for the stated purpose. Schedule 40 PVC 3/4" or 1" painted black is a good choice as it will allow a good flow of water still allow it to have time to heat depending on the length of the pipe. Using multiple U shapes will allow the water the best amount of time to heat. Hope this helps.

More likely polyethylene pipe -- available any farm store. PVC is expensive, rigid and environmentally evil. That said the water can get hot enough to melt poly, especially in summer when you don't actually need the heat for the pool. Using PEX pipe will reduce the chance of this happening,but it costs more.

If you are heating domestic hot water, the vacuum tubes with the high efficiency coatings do a better job -- at more money. Use a simple cheap system as a pre-heater.

DavidS925 (author)stad1682017-12-28

Make an X out of 2x4s. You're going to spiral black PVC irrigation tubing through that X by drilling holes in the wood. It takes effort as the radius gets smaller, but you can get the whole 100 feet in there. Then enclose it in a box made from 5/4 deck boards. A back made from Styrofoam painted black and a front made from corregated roofing completes it. You need to make a bypass in your pool plumbing and allow only some of the water into the heater so it sends enough time in the coil to get warm.

Lillyvilleky (author)stad1682017-01-17

I haven't thought about that, however I have seen people use black tubing made into coiled circles to lay over their pool to heat it, and yes it works. As for running it through the cans, I'm guessing you would need some sort of a pump to pump the water through, but I think anything is possible (with sunshine and a little pink!)
-lillyvilleky ; )

jgh59 (author)Lillyvilleky2017-09-01

My sister's pool has a black rubber mat with tubular channels molded into it. The pool's circulation pump drives water through the channels and back into the pool. The mat is the length of the pool and about 3' wide, mounted on an inclined plywood board than is facing south. It picks up sunlight for about 75% of the day. In the heat of the summer, you can't even use it because the water gets so warm; fortunately there's a by-pass valve. In the spring and fall, it keeps the water around 80-82° during the day which really extends the swimming season.

SH8RRY (author)stad1682017-01-17

Very interesting idea and one Ive been working on for awhile. If you find any ideas or get any suggestions, I'd be very interested in hearing about them! :)

Left-field Designs (author)2017-12-28

I build this guys big brother as one of my earliest instructables. As suggested by you I set the angle, 35 deb and due south in Ireland. I also added the ducts to the barn and a 12v pc fan with a solar panel to regulate the airflow on really hot days. it really works well even this far north with not particularly sunny days.

mrjoeyman (author)2017-12-28

Personally I thought the plans were very sufficient. What a good idea.

RickW29 (author)2017-12-28

Pretty cool idea. I would love to expand on it, perhaps more cans (deeper) or; I wonder what would happen with pvc pipe?

michl (author)2017-12-28

I built one of these 2 years ago and mounted it on my south-facing deck. I made it with 99 quart tomato juice cans that a local deli saved for me. (I also drink a lot of tomato juice.) I cut the bottoms out and used HVAC tape to attach them together. I made a very well sealed and insulated 4-1/2' X 6' box. I used a double wall clear acrylic panel for the front. Piped in return air to the bottom and heated air exits the top. I installed a computer fan at the exit hole. On a sunny 20° day I measure more than 155° (as high as my thermometer goes) coming into the house. With the fan off at night, the temperature in the box usually stays about 50°. Pretty much a free source of heat since it's basically only reheating inside air. Only cost is a tiny bit of electricity for the 12 volt 20mA fan.

I f I built another one I would use large black gutter downspouts instead of cans.

sgbotsford (author)2017-12-28

More info at on this sort of project.

If you want to heat a space with this, you need to run two ducts to its, and move the air through it with a computer fan and a 12v solar cell. Put a thermostat on it, and only move air when the air is above 80 F.

However: This doesn't collect any more energy than a window of the same size. The win is that it doesn't drain energy at night.

You can get almost as good an efficiency by just using a box with black paint inside.

You won't get an increase in temp, but you will be able to move more air through it if you insulate the back with slab of foam.

I read of a farmer in Montana who made the south wall of his shop into a solar collector like this. Tarpaper, 2x2, clear plastic on the outside of the insulated wall. Plenum at top at bottom. Used a furnace fan to pull air in from the top when the temp got up to about 70F. Even in midwinter shop was warm enough to work in by 10 a.m. and remained so until about 5 p.m. If the rest of the building were better insulated it would still be warm in the morning.

ShawnS60 (author)2017-12-28

I like it.
I have seen a similar “oven”, which is even more simple, usising an old window. We used to go camping with friends a lot more, when we were younger. The idea was to prepare some food in advance...we sat it in a cardboard box lined with a black trash bag and covered it with an old window—like an extra storm window we found in the garage. After playing out in the river for a few hours, canoeing, swimming and floating on tubes, we arrived back at camp to a heated up meal! Similar to leaving leftovers covered in foil in a 200 degree oven for four hours. It wasn’t haute cuisine, but it was hot food, pull a watermelon out of the cooler for dessert, and it ranked among the most satisfying lunches I’ve had!

dragnit (author)2017-12-28

This might work in Florida or in summer but does nothing where I live.

jatkins729 (author)2017-12-28

Been in solar since 1980’s. While commercial system materials are hard to match,the old beer can heater works pretty well. The main challenge is the temporary duct to heat the living space. And it needs to be ducted, so that new, cool air is always entering. With greater delta t the exit temp will be lower, but the total Btu’s out will be greater. Pool heaters work well, too. Much better with a nighttime pool cover. The rule of thumb is: with no cover, solar collectors need to be twice as large.

RodgerT (author)2017-01-20

Hit & Miss however it looks like you're on to something here Lillyvilleky,, I am definetly going to build at least one of these and probably more for my shed to start out with and then my garage. Thank You fir the inspiration.

Lillyvilleky (author)2017-01-17

To use it, you can move it inside. It will continue to give off heat for a while. You can also attach a computer fan and hose-as others have said-to blow the warm air into your home. I did not have a computer fan and didn't want to buy one for this project, nor did I want to put a permanent hole into my home for this unit. It was more of a project to see how cheaply I could generate heat. Say for instance, homeless people outside who don't have heat but still need to stay warm without starting a fire, or using electricity. You can put this outside in the sun and still be able to stay warm if you are near it. Plus it was practically free to make.

arthbutt (author)Lillyvilleky2017-01-18

If you have, or put in, an air vent or brick could you fix something like a tumble drier vent pipe to the top of the panel and then to the air vent (as long as this is higher)?

Lillyvilleky (author)arthbutt2017-01-19

Yes, I suppose you could as long as it was to an inlet vent.

GeneB12 (author)Lillyvilleky2017-01-17

You could use both top and bottom (intake output) hoses then make a window adapter to run the hoses through, easy pleasy! I love this idea (: Then place both the hoses low to the floor but separated if you used a muffin fan to circulate the air. We have bright sunny days with 0° temperatures here most of the winter!

spark master (author)GeneB122017-01-17

again Mother Earth News heat grabbers for every applicable window, unlike awning they go under not over, the window. You could do an exterior wall if situated right and cut in vents top and bottom make a Trombe Wall.

JetMechanic (author)2017-01-17

Remember to let the paint off-gas in the sun for a few days before
using this to space heat, so you don't poison yourselves. And while
we're on that subject, realize that high heat paint isn't really even
needed in this application. It's just not hot enough to fry most regular
acrylic spray paints.

Lillyvilleky (author)JetMechanic2017-01-19

Good point, thank you. Yes, off-gassing is a good reminder to think about.

long gone (author)2017-01-17

Nice article. The concept has been around a while, but it's great to see people being introduced to it. Here's some additional information using the same principles:

Lillyvilleky (author)long gone2017-01-19

Thank you for the link! Yes, I first started researching ways to save on energy on my own because of how high our utility bills were. You are right it is not a new concept. That is what amazes me is that it is actually a very old concept, yet around most of the country we have abandoned building practices that take advantage of our plentiful natural resources. Dating back to the 5th century BC the ancient greeks even built their homes to maximize the sun's potential.

Once the invention of central AC, and quick stick built homes came along, I feel like the importance of passive heating and cooling was lost : (

PhilS43 (author)2017-01-17

"tin cans" like baked bean or soup cans, are wonders of engineering. Hugely strong, I never throw them in the bin.

From nail storage containers to cheap ducting, endless uses, including 0.22 targets at end of life.

Tin-plated steel cans can be soldered, but Aluminium cans are tricker to deal with. A good duct tape - aluminium metal tape is my preferred tape, is the easiest to work with.

Even in the depths of winter, the sun provides a useful amount of radiated heat. Under my roof tiles (concrete), I record temperatures 20 to 30 degrees Celsius higher than than the air temperature.

Lillyvilleky (author)PhilS432017-01-19

Yes, they are so renewable it is awesome!

jodiwer (author)2017-01-17

I still don't get what you would use this for? Doesn't it have to be outside in the sun? I have no need to heat the outside.

TexBoyd (author)jodiwer2017-01-17

See the link below:

Lillyvilleky (author)TexBoyd2017-01-17

Yes! Very cool!

Thank you!

nobodys nobody (author)jodiwer2017-01-17

What can you warm with it...the outside? Its cool but how do you keep something warm with it?

Build it into the wall of a doghouse and have a very happy Pooch

Lillyvilleky (author)anoldwitch 2017-01-19

That is a great idea!

What is so hard to understand? You place the collector outside in the sun and run some type of duct, insulated would be better. Since hot air rises the duct from the top runs into the house or whatever and the duct from the bottom runs from the house near the floor to the bottom of the collector. As the heated air flows up through the collector and into the house the cooler air is pulled through the duct into the bottom of the collector heats up, rises and makes it's way into the house. No fan is needed and the circulation should continue to increase as long as the heat rises. It could be used as supplemental heat during the day but would be useless at night.

Please see top reply.
-Lillyvilleky : )

Stancolorado (author)jodiwer2017-01-17

Really? Almost anything that makes heat is useful. Free heat? Unbeatable. Duct the top of the heater into anyplace in the house above the top of the heater and presto! FREE HEAT!

Lillyvilleky (author)jodiwer2017-01-17

Please see top reply.
-Lillyvilleky : )

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