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 ; )


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?

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.

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

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! :)

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

Yonatan24 (author)Njturner842017-01-23

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

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 : )

JDevious (author)jodiwer2017-01-17

If you had a portable (stand-up) AC unit that ran a hose from a window into the unit, I assume you could turn the window mount around and run that same hose to the heater, then the air would naturally flow in through the window mount. Presto, heat in the winter, cold in the summer.

DonD44 (author)2017-01-19

I made one back in 87 out of wood, worked great but to heavy so If I ever make another one it will be out of two aluminum storm doors, insulation on the back side & every thing painted black even the frame so it will conduct from every were. very nice job & well worded. thanks

Lillyvilleky (author)DonD442017-01-19

Thank you! I agree, if these were lighter they would be very better! I have been experimenting with using foam board for the entire project, I just need to get a lighter glass, or plexiglass : )

IrisW6 (author)2017-01-18

I like the sheet metal idea if one could focus part of it towards an outside oven made from glass, hang a piece of meat and cook it?

Nickoftime66 (author)2017-01-18

Would using black tape around the cans not be as effective for conducting heat?

rxqse2 (author)2017-01-17

Forty some years ago I took 4 50 foot hoses, attached together giving me 200 feet.... I coiled the hoses into 4 big flat circles. Plumbed them together. Then set the coils into my pool pump/filter building. Painted them black, built a box around it all after securing to the roof.
I then connected to the pool pump.
The output was hot enough to raise the water temp by 15 degrees on a sunny spring day. (Input temp vs output temp)
Have a great day ..

Mick Gibson (author)rxqse22017-01-18

About 50 years ago I went out with a girl that the family had a pool that had heater defunked. I look at the pool and there was a shed that had a metal roof that faces the sun. A sheet of black plastic 12' x 30', a wore out hose, and plastic glue. I folded the black plastic in half, cut hose to the top and bottom, drilled the hose for the top, cut the hose in 1/2 for the bottom, used the glue to patch any holes, and attached top the pump and the bottom go into the swimming pool. In two day the water was TOO hot in the pool!

GeneB12 (author)rxqse22017-01-17

Any idea how many gallons the hoses hold? I know that my off grid neighbor uses one 50' black hose from his cistern to his home and turns off his hot water heater in the summer. Funny but it makes the spikets backward, the hot spikets run cold and the cold hot (:

Luna- (author)2017-01-18

Thanks, going to try.

sshepard (author)2017-01-17

Imagine lining an entire greenhouse with this concept! lol

This is rather cool. I like it and the "How do you use this?" questions, though logical, are tedious to a point. Use your imaginations. :D

c9tds (author)sshepard2017-01-17

Thats already a thing, it's called thermal mass greenhouses, usually they use somthing bigger than a soda can, like a back wall of 50 gal drums or i use old water heaters painted black with all the insulation stripped.

MarcelS9 (author)2017-01-17

Cool..uhm, hot I mean. This can only ever be a means to an end in my opinion. What do you do with it? How can it be put to use?

GeneB12 (author)MarcelS92017-01-17

Use your imagination. If you still cannot see a use, than a DIY solar heater is most likely not for you. Here is an example of what pops into my imagination. I see in my mind building myself the coolest tree house with the most superb zip line ever ending at your swimming pond (remember, it's my imagination here) ever!. Me and my Buddies have been smoking the West Coast ganja and drinking beer up there playing on the zip line into the pond but get chilled when trying to drink the beer. Even though it is sunny, the temperature is only around 40° to 50° even sumertimes here on the high desert. So now here you sit shivering in the sun when you spy all the beer cans laying around underneath the treehouse........see where I am going with this? You replace your treehouse south facing wall with this solar heater AND also get rid of that pile of cans littering the base of your tree (:

Lillyvilleky (author)MarcelS92017-01-17

Please see top reply.
-Lillyvilleky : )

GeneB12 (author)2017-01-17

One would have to run some sort of duct or dryer hose to channel the heat to the interior of a room. Even better hose both intake and output positioning hose/ducts so it draws cold air from your floor heating it, then expels warm air back into the room

Fhyre (author)2017-01-17

How to get the heat into the house: I made a similar one of these many years ago. I took a full sheet of plywood and cut it in half the long way, so my solar box measured 2 feet wide by 8 feet long (I had a piece of glass that fit that size.) Old shower doors or old sliding glass doors work well for this. At any rate, I suggest making something at least six feet long. I made it the same way described here, minus the cans. I used sheet metal for the inside, though I think the cans is a better idea. At any rate, when I was finished building it, I brought it to the south side of the house I was living in, set the bottom on a cinder block and leaned the top into the bottom of an open window in my apartment. It only had to go in far enough to clear the inside window, so the window, when shut, would land on the end of the solar box. Then I insulated around the top of the solar box, where it came into the house, in order to make it air tight. During the day, while I was at work, the box was putting heated air into my apartment all day. Even through a Connecticut winter, the box was warming my apartment all day even with the heat set at 55 degrees. I would get home and it would usually be about 70 degrees in my apartment. Once the sun goes down, or on cloudy days, there is no heat from the box so I cut a piece of rigid foam insulation to fit snugly into the rectangle opening at the top of the box to act as a plug to keep cold air out. Even if I didn't put the plug in, cold air really wasn't a problem as it goes low and the box (except for the opening) was lower that the opening in the window. My heating bill was significantly lower that winter!

DDW_OR (author)2017-01-17

this could be used for a solar kiln to dry wood. add a solar-electric panel to power a small blower to make the kiln self-contained.

CBGjr (author)2017-01-17

Great job! I made a similar one with Plexi and fiberglass screening. Make sure you use a blower that can handle the static pressure or all the flow will escape out the back of the fan with very little actually moving through the system and pipes.

hholland419 (author)2017-01-17

How do you use the heat generated? Port it into the house? I'd like to see details on this

Lillyvilleky (author)hholland4192017-01-17

Please see top reply.
-Lillyvilleky : )

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