Introduction: Beer Can Solar Space Heater

Picture of Beer Can Solar Space Heater

I saw a smaller version of this instructable a while back: here. At the time I was volunteering with a local animal rescue center. We had just installed a new 20' x 40' wooden barn as an indoor recreational area for the animals, but as the shelter was off grid there was difficulty heating such a large space. I decided to upscale the idea and see if it would work for us.

For this instructable you will need:

  • 8 x 4 sheet of 1/2" marine plywood, the marine ply allows the unit to be outdoors without the worry of delamination.
  • 128 full size (500ml) beer cans.
  • 1 sheet of 8 x 4 6mm laminated glass (please use laminated safety glass cut by a specialist glazier as glass cuts are nasty).
  • Lots of 3x2 timber.
  • 2 x 4" dryer vent kits with ducts.
  • 2 x 4" PC case fans.
  • 1 x 15W solar panel.
  • Black Barbecue or oven paint (this is required for its resistance to the high temperatures inside the heater)
  • Assorted screws & high temperature sealant.

Step 1: Prepare the Cans

Picture of Prepare the Cans

First let me warn against trying to make all the empty cans yourself, this much beer is not healthy!

We put out an appeal for empty, un-crushed and washed out beer cans.

Each can will form part of a hot air stack or chimney, for this wee need to allow for air flow. The easy part is to remove the pull tabs from the top of each can, next you will need to make a similar hole in the bottom of the can. I used a step drill to make a 20mm hole.

Cans are designed to stack so this part is easy, I placed one can on top of the other and used some sealant as both a glue and a method to keep the hot air in.

I needed to leave space on the 8 x 4 sheet for a collection area above and below the cans so I limited my stacks to 8 cans high and the best fit for the sheet was 16 stacks wide.

Step 2: Prepare the Housing

Picture of Prepare the Housing

Unfortunately my camera ran out of power so I have no photographs of this section.

Make a frame around the edge of the 8 x 4 using the 3 x 2 timer (mounted with the 3" as the upright)

Also make a retaining bar for the cans at the top and the bottom of the stacks, each of the retaining bars will need a 40mm hole drilled corresponding to the stack above or below, this will let the air through.

Finally drill a 100 mm (4") hole in the top and bottom collector areas, your vents will fit here later.

Step 3: Finish the Heater

Once all of the timbers are in place and the holes drilled, insert the stacks into the chamber and paint the whole inside of the unit black with the barbecue paint, the black paint will allow the unit to absorb more heat (rather than reflecting it, also the thin walls of the cans allow for a very fast heat transfer).

For my unit I wanted to have a degree of control over the heat passing through the unit, I had read that the heaters are quite efficient even on relatively overcast days so I decided I didn't want lots of heat on already hot days.

To prevent this I fitted 2 x 4" PC case fans and a small 15W solar panel, there are no fancy electronics here just the principle that the more sun light the hits the solar panel, the more power is generated and the faster the fans blow, the faster the fans blow the less time the air has to heat up in the unit and hey presto less heat on an already hot day!

Finally mount the glass, I had this predrilled by my glazier as drilling glass is a dangerous business and I'm not set up for that. Before I locked the glass down I gave the inside a good clean (as access is no longer an option and sealed the glass to the frame with the high temperature sealant.

Step 4: Mounting

Picture of Mounting

The heater is great but at the moment its just a big hot lump of parts. I decided to mount it on a free standing frame (other instructables mount directly to the wall). I obviously wanted the unit to be as efficient as possible so I placed it on the south face of the barn and after a quick check for my latitude (Dublin, Ireland) it found that 35 degrees is the optimum angle for a solar panel (this goes for air and water heaters as well as PV cells)

I drilled corresponding 4" holes in the barn and mounted the dryer ducts. The duct on the bottom draws cold air from near the floor and pulls it into the unit, the air heats in the stacks and blows back into the barn near the ceiling, I know this means I am heating the highest space first but the building has a low 6' 6" ceiling height, also the air coming from the unit is about 15 degrees C hotter than it went in from the bottom.

I fitted the one way louvered vent on the top duct, this means that hot air can blow in on a cold day but it doesn't get drawn back out on a cold night when the heater is not working.

There you have it, happy warm dogs and volunteers. P.S, this all cost around 150 euro as some of the parts such as the timber was already on site.


Lovetra (author)2017-12-29

SODA POP cans are the same as beer cans in building this thing and mine is going together this week pretty good. Where I am struggling is with the thermostat and wiring to open and close the 4 inch duct vent fan on the cold air intake in my set up. I am not sure what type of thermoeter to buy! This first heater is an experment because the structure I want to heat is 24 feet x 26 feet. I am in in the heart of California and the temp here rarely gets below 25 - 20 degrees. Thanks

A regular old pt100 thermal probe would work. What I did was hooked a pc fan directly to a solar of panel, that way the hotter the day, the faster the air moved through allowing less time for the air to heat in the system.

ludgidiya (author)2015-10-13

I'm working on the same project. What high temperature silicon do you use for gluing the cans? How is the efficiency at negative temp. C?

I used a product called tek 7 this works up to 70deg c

McGiver30 (author)2015-09-22

How come you didn't paint cans black to absorb the heat?

the cans are painted black, as I said in a previous comment it just doesn't look like it in the last pic as some of the cans have an embossed logo

ScienceDiscoverer (author)2015-08-25

"First let me warn against trying to make all the empty cans yourself, this much beer is not healthy!"

Any amount of beer is not healthy. Even 1 molecule of it.

Beer= goodness!

lorre (author)ScienceDiscoverer2015-09-02

American beer is not healthy, begian beer is healthy ;-)

Left-field Designs (author)lorre2015-09-05

Irish beer is pretty good too!

Beer is a mixture, there is no such thing as a "beer molecule". And most of it is water, so if you were going to pick one as the "beer molecule" then it would be fine.

Yea, C2H5OH is a beer molecule, and any other alcohol poison "mixtures".

Pretty sure that's actually ethanol, which is in every alcoholic beverage. so it is as much a beer molecule as it is a wine molecule, and would be even more of a vodka molecule.

tikot (author)ScienceDiscoverer2015-08-27

C2H5OH is ethanol. Beer is a complex mixture. C2H5OH is ONE component.

Also C2H5OH is ethanol, not necessarily beer...

I never stated that any quantity of beer (or other alcohol) was healthy, but people will drink beer. I merely wished to caution against drinking large quantities of beer. Similarly there was a comment regarding soda cans, and similarly I would caution against drinking large quantities of soda as this is also unhealty, just in a different way.

tikot (author)ScienceDiscoverer2015-08-27

Yeah, right. Chicken will kill ya. A doughnut is slow death. A steak will cause you to grow breasts due to the hormones used. Water (h2o) will cause problems because of the drugs that were flushed down the drain. A gun will pull its own trigger to kill you. Marriage is bad for you. Your point (even though doctors will disagree with you)? Don't like beer? Don't drink it. Drink the contaminated water.

WastelandMan (author)2015-09-01

Since heat rises, you are putting the hot air out in the correct location. If you were to try to inject the heat at the bottom of the wall it would lose all its thermal energy by the time it floated up to the ceiling. By injecting the hot air at the top you create a layer of heat that eventually creeps downward, and heats the room more efficiently. It's all a bit counterintuitive, but that's the way it works.

Exactly I always ask people to visualise thick smoke filling a room, it starts at th ceiling and fills from the top down

rhfaber1 (author)2015-08-30

My students used Lexan to cover their class constructed glass solar cells on their solar powered car. Transmission is better than 90% with resistance to UV which clouds plexi.

good tip, thanks

GaryD13 (author)2015-08-26

I have some clear 5mm polycarbonate sheeting laying about in my garage. Would it be a suitable alternative for the glass? (author)GaryD132015-08-27

Yes, one of the biggest issues with glass, is that it isn't really just clear glass letting in all the suns ray's. Most glass found in windows, patio doors, etc. is Low E, blocking ultra violet rays & such (so your curtains, furniture etc. don't fade. If you use plastic, just make sure it is a non yellowing type, or you will regret it after a few years.


Also it is a good idea to insulate your box with some type of board insulation, or another type. If you get the foam sheets, make sure at least one side has plastic, or aluminum on it, because plain foam tends to melt into a gooey mess from spray paint (flat black being best)


yes, I have read some studies that suggest polycarbonate is more efficient than glass for greenhouses so would be better here.

yes, I have read some studies that suggest polycarbonate is more efficient than glass for greenhouses so would be better here. (author)2015-08-27

smurry2, what is the benifit of the cans? I attached a picture of how I made a couple about 20 years ago, you only need one rectangle hole into you building of choice, and the unit will never flow backwards when cold, without the use of vent traps etc.


the cans have a thin wall that transfers heat easliy, also the joints create pinch points that show the rise of the air throught the stack alloing more time to heat. a simple black box would probably work and i have seen other units with black pvc pipe, window shuttering or rain spouts, this is just one way to do it. (author)

I forgot to add that I just used a adjustable disk type (clicks on) thermostat, set it to come on around 100 degrees F, and off at around 85 degrees F. Also I covered it with a sheet of insulation during the summer, seeing I am from WI. USA.

I do like that you added a solar panel for its 100% independant, still blows heat if the power goes off & that's when it really appreciated.


Suzanne in Orting (author)2015-08-26

Not trying to be snarky, really want to know.

Is there a difference between beer cans and soda cans?

Suzanne in Orting

No, good question. there's no difference except in ireland soda typically comes in 330ml cans and beer in 500ml cans so they are bigger hence I needed less. also with more cans there would be more joints meaning slower airflow. Thanks for the question

No, good question. there's no difference except in ireland soda typically comes in 330ml cans and beer in 500ml cans so they are bigger hence I needed less. also with more cans there would be more joints meaning slower airflow. Thanks for the question

Slim49 (author)2015-08-26

That is Ingenoiuus!

thanks but credit to the original author


Razanur (author)2015-08-25

It look awesome, but I don't really get what this is for...
When it is hot outside (so if this is most efficient), I want it cool(er) inside, not hotter? Plus: When I really want it to heat up the room, it is cold outside; Without insulation isn't this an additional room cooler?

It heats a lot when its cold but bright out and not so much on warm days. its a compromise for free heat...

Debbie451 (author)2015-08-25

In step three you mentioned insert the cans then paint it all black. Do you paint the cans black? The picture seems to show the cans unpainted. Painted would be more efficient, right?

the cans were painted after fitting, no advantage to painting the backs of the stacks just wasting expensive paint. have alook at the finished image, of the interior is black

FN64 (author)2015-08-26

I've been looking at these for some time as an add-on for my wood shop.

I have several lengths of older rectangular aluminum downspouts that I think might fit the bill nicely. Have a couple dead computers I can strip for fans, a bunch of scrap wood laying about and a small solar panel that's not doing anything.. Gotta cost out the poly-carbonate & a few other tidbits but I think I'm gonna have one of these on the south side of the barn by winter.

I do think I'll add a cut of switch for the summer months..

Great 'ible!...FN...

Left-field Designs (author)FN642015-08-26

sounds like a good plan. even a shutter over the vent into the shed to stop airflow but make sure to vent tje heat from the panel to the outside to prevent over expansion if you are in a particularly hot climate

trx1 (author)2015-08-26

Abut 5 years ago I made a small test collector and tested out a few different designs including one using cans like this one but found a dual aluminum screen collector design to be more efficient and easier to build. In the end I built a 8' x 12' collector to provide supplemental heat in my shop (30'x30'x12'). In full sun in the winter it can raise the temperature about 10 degrees during the day. That means during sunny days my furnace does not have to run (set to 40 degrees to prevent freezing stuff) when it can be single digit temperatures outside. With any solar air heater, higher volume of air flow increases efficiency even if the output temperature is reduced.

schmitty66 (author)2015-08-25

It is late and I did not proof the spelling and it shows. I also hit my thumb with hammers and trip over things.

schmitty66 (author)2015-08-25

different system- 4x8' 5/4decking, 4- 3x3 angle brackets attach frame ti side of house around a south facing window. seal using soft foam material. I had a large road sign and panted it flat black. set sign on small blocks so air could get under it. and over the top. placed top of frame just above top of window and let it extend well below the window. screw 2 polycarbonate sheets on the front. open the window top and bottom .put a thermometer on the back of sign and watch the needle get buried over 120 on a sunny day. I open and close the window based on the temp. on the back of the sign. Because the alum. sign is thick it is a good heat sink. and a passing cloud doesn't have an mediate effect. I get passive air flow from the hot air at the open top window. and cooler air goes in the bottom half. In winter I get above 70 between 9&10 and close 3-4. material is HD or Lowes. Metal could be beer cans. Holes would no be needed if air flows around them. One or two legs could be used if attaching to the house is a problem. They would have to be angled away from the wall and anchored so the wind does not move it.For one person it is easier to hang the frame and then add heat sink make adjustments and them put on the front.

If no one is home the window stays locked.

A bigger system against the house with forced air would heat the entire first floor. If a basement and first floor window could be covered it becomes real efficient. Cool basement air is heated and replaced with warmer air from the first floor as it is pulled down

SabinaCowan (author)2015-08-25

Wow, working on this project as we speak!! Just finished my 25th can of beer.....

hvweezel (author)SabinaCowan2015-08-25

Go on. When finished you will not need a Space Heather any more ;-)

gcai_fwb (author)hvweezel2015-08-25

are you helping SabinaCowan ? Space Heather? :)

AnnieC3 (author)2015-08-23

In 1970 we did something similar. Take:-

1, Bungalow roof facing south.

2. 7ft radiator painted with blackboard paint.

3. Roll of fibreglass insulation.

3A. please look after number 11.

4.Exterior ply and some wood for box.

5 Assorted copper tubing and joints.

6. 1 pump

7. several sheets of conservatory glass.

8. Backboiler of our coal fire.

9. 1 ladder

10. 1 old man with a pipe to sit on base of ladder.

11. A wooden mallet

OOps! nearly forgot the turkey foil (to go between the radiator and the fibre glass.)

We drained down in winter as the fire heated the water. Then in the spring we hit the pump with the mallet to dislodge any bits of corrosion. One real danger point for me was standing on the ladder offering up the sheets of glass with my head back to assure a safe transfer. That's when you think "Does he really love me"? The drawback - we lived in Kent UK and had to wait until midday before I could wash the nappies. Have to admit beer cans would be cheaper these days, but I think beer came in bottles or from beer engines then.

Well done for your ingenuity.

Kdemon (author)AnnieC32015-08-25

You wouldnt have a picture of your old setup would you?

Sounds innovative... I was thinking of something similar for hot water, I have a tank with an indirect coil but I have read that you need to heat the water above 70 deg? regularly to prevent the risk of legionnaires disease so back to an electrical heater. This project only heats air, however the principle stands, sun a on dark surface creates heat and convection does the rest. Thanks for your comment :-)

We tried using an indirect coil and found it was more or less useless. As I recall we lost about 75% efficiency. Without the indirect we got hot water. I don't think we had heard of Legionaires then.

About This Instructable




Bio: I am an automation engineer but I will give anything a go. I don't know if you call if pessimism or just being an ... More »
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