Check out my followup video here: https://youtu.be/5IHJbloiTs8

I'd like to make a couple of suggestions. I built my beer can heater six or seven years back and I don't believe it cost me even $100. First off there's no wood other than the two boards that feed air in and out of the cans. The box itself is two layers of foil faced foam board. Never had an issue with it not being able to handle the temps. Now it's not a flat box. Up at the top it turns down at an angle that matches the suns elevation in winter. The top portion fits into a window so it draws inside air that is heated and blows back into the room with no electricity needed. The box is built as a thermoplane. It has a raised bottom that is around three inches above the bottom and topped by a sheet of foil faced foam. Air flows out of the house, down the lower chamber and then through the rows of cans and convection blows the air back into the house. The cans are all drilled out on both ends and then glued together in a row using liquid nails. The cover is corrugated greenhouse plastic. All caulked and sealed with metal tape. In my area it provides heat from around 10am to 4pm. It raises inside air temp around fifty degrees each pass and can easily heat almost a thousand square feet of my home. I have a simple plug made of foam board that fits in the opening of the piece coming through the window. I put a temp sensor inside the output portion and when the temp drops to the inside the house temp I put the plug in place and leave it there until the temp rises enough to provide heat the next day. The heater is around eight feet long with an additional two feet that goes into a window rather like a window ac unit. A piece of foam on each side and a gasket across the window on top so the the window is closed down to the unit. All together it might weigh less than ten pounds. So far it's held up to wind, rain, even hail and still worked fine.

Gonna have trouble finding 300 pop cans. However if I could use beer cans. I can probably have them ready in a few hours.😂

I made mine out of aluminum dryer duct (a bit easier than cutting and connecting all the pop cans) painted with SolKote. Built the insulated box and snaked ductwork up and down about 26’ in length, into a manifold with 6” inlet and outlet.
I added some backdraft dampers to the air supplying ductwork to enable a winter heat mode, and then switch the blower to exhaust excess heat in summer mode.
I made 3- 4’x8’ solar heaters, placing them within a rooftop enclosure. Used insulated 8” ductwork for intake and exhaust grills to heat three areas of the house. First winter use saved 400 gallons of fuel oil, about 1/3 of yearly volume. Been saving every year since!

I remember when the Mother Earth News was rich in this kind of info . I don't find them all that useful anymore. I had about 100 old issues from the 70s that I gave to a young couple who bought some land and wanted to live more independently. They were amazed at all the information they got. Good to see people getting interested in this kind of thing. Being screwed by the cost of energy and over regulation has a way of waking up people who can think outside the box.

I am an old retired HVAC specialist, and have been using these and other similar products since 1970, so please pay attention to this old man's advice.  One is I don't use any kind of foam product, and only a few these of high temp silicone on these devices. For insulated board that is both fire and melt proof I use 1" shielded Duct Board, it is a ridged fiberglass bat type panel with aluminum facing both sides.  You can use a straight edge and a utility knife to cut it to shape and as long as it stays dry it will last a lifetime. It has a high reflective surface so it doesn't require paint, you Want it to be reflective to get more coverage around the tubes. I also use a metal header board and 4" spiral steel piping, a commercial grade of ducting, and weld these to the sheet metal headers before painting the assembly and installing it in the box.  I prefer a fiberglass of sheet steel box over wood because that is heat and moisture proof, but wood works just as well. leave a small space between the tubes, let the air circulate around the box, with at least 3/4" space between the poly or glass cover, and I prefer two 1/4" thick pieces of HDPE clear sheeting, pricy but it is hail proof and two layers give it more insulation value in front.  Use a good quality rubber seal when applying the clear covers to the box to prevent air leaks. Another option is a silicone product called Fire Stop that comes in a regular tube works well and is permanent. Two 48" x 96" boxes on your roof will heat the average home with a good commercial grade circulation fan (not a PC box fan) and attach internal box temp sensor switches and a room thermostat with a 10 amp rely to switch on the circulation fan, as well as one commercial grade 6" motorized damper to close when a second low temperature temp switch and relay circuit register it cold at night.

These grade boxes in metal and commercial grade (not pop cans) tubing and insulation, etc., will run around $1,200 per box but will last a lifetime with little maintenance.

I am happy to read this, quite a level-headed, rational account. It also reflects many of my thoughts and concerns/considerations. I have seen such units sold as commercial products in Scandinavia (not beer can, of course but some other kind of absorber but same design), they are used on vacation homes around the sea to keep ventilating the huts to avoid damp and mould building up, they have their own built-in pv inside the panel at one corner with a super-simple fan to help ventilation.
Those units are not super cheap (one can find some on the net) but they have one critically important thing they can do and no heat pump, EG4, lithium etc... can do: they are absolutely self-contained , super simple, zero battery, minimal moving parts (most of them work even with the fan removed). You mount it outside the wall, two holes (one on top, one at the bottom) and you are done.
Yeah, you can have PV panels: then you need batteries, charge controllers, fuses, some heat insulation for the lithium batteries or maintenance of lead-acid, then control electronics for the heaters... anything but simple and you still have to maintain it somehow. If you even add a heat pump it gets many-many moving parts, seals, tubing, further electronics...
If you want all that complexity for performance and other reasons: great, build it, pay for it, have fun with it.
But if you only want to make sure your place gets some dry ventilation and some baseline temps, ESPECIALLY IF YOU ARE NOT ALWAYS THERE, air thermal solar (as they are marketed) is a good option, especially on cold climates.
Some people heavily misunderstood this design tho - because it was using basically scrap beer cans for absorber people tend to think they can throw together anything and it will work well.
Nope. This has to be decently designed, with careful material selections and some serious testing and some calculations.
Jarhead mentioned some - this design is inherently prone to overheating, as any other thermal solar. I would not use ANY plastic-based foam (PU or similar) as insulation but stuff that is normally used in furnaces or similar. I would also argue OSB is a questionnable anywhere inside insulation as it is held together by resin that may outgas some nasty stuff at elevated temps. Same about fittings, even temperature tolerant plastic has a relative short life span under high temperature variations.
There are other things that made me wonder - how about water condensation between the absorber and the front glasing - you have to allow water to leave but you have to make sure no insects etc can come in the same way - it is also easier said than done.
All in all, if you want these units not only "work" but "work well" and not only survive a summer but last for many years, you have to be willing to put in serious thinking, a bit more money than scrap and some iterations - don't be discouraged if the first or second approach doesn't really work out.
After all, those companies are on the market exactly due to this.

Years ago the mother earth news built a similar solar heater.  They just fastened a piece of plastic sheet over the exhaust.  You need to have the exhaust outlets open straight up and down.  In your case, maybe use a 90 to make that happen.  The plastic is so light that it opens with convection but prevents backflow.  Thankyou for posting.  Very informative

I like how people add HONEST to their videos assuming the viewer will believe this over others.

i built one 2010 still works great today 2026 febuary working as we speak saved me 1000s and im in canada north

Thank you for the honesty, I knew there was something 'too good to be true' from videos that advertise these to be like $8.

I had a friend build one and instead of using cans he alternated channels from roof material at slight angles all the way through the heater so that air had to chase its way through as it warmed up . He trimmed the ends of each piece of flashing roofing material to allow hot air to make it around the channel and go into the next channel he pushes it through it’s beautiful during the final chase out was maximum heat. Really a pretty awesome set up

Great visuals. The illustrations, diagrams, and detailed schematics really helped make sense of your loose description.

$700?!?!? I built one but instead of using pop cans, I used three passes of aluminum window screen at an angle inside the box. Front top corner to bottom rear corner. LOTS of surface area, and it's already black. Simple dryer flap to prevent back flow, and a free door wall from facebook marketplace. That nets you two, double pane insulated glass panels so you can build two of them.
The window screen has more surface area than the cans, and doesn't restrict air flow. That set up comes in at less than 1/2 of your cost.

Thanks for the update. I used down spout since I drink very little soda and no beer. Had a HF solar panel to power a 5V computer fan and a 120/90 snap switch. ducted it to draw air from ceiling while exhausted to the floor. Worked good as supplemental heat until the wood frame rotted after a few years and didn't feel like fixing it.

This is the first time I've seen someone give a 'review' of their can solar unit after years of using it.  I have often thought of making one of these but wasn't sure if the time and money invested would be worth it.  I think I'll try it- I don't have great solar in the winter for the barn I want to heat, but this may have some positive effect and add to the space heater I'm thinking of using. Thanks for this video.

First time viewer to channel but I loved the video, although I'm no handyman, do it yourself person.  I loved learning new things and the description of the how and why, doing it was interesting as show creativity, trial & error and problem solving of people and analyzing/trouble shooting problems.  This is great channel for homesteaders and such, like my father-in-law was growing up remote Volcano area outside of Volcano National Park in Hawaii county of the family farm in the 1930's.   Even until his 90's, my father-in-law was still patching his tin roof of the family's house which was a raised home, so it would have been the height of two-story home.  Up there, there was no wells or water lines, they had four huge water catchment tanks to collect morning dew.  Being at that elevation outside of the Volcano Park, I know it dropped was pretty cold, being about 40 degrees at 6 am, which for a tropical island is darn cold.  I imagine living all his life on a 15 acre farm in the countryside with no streetlights surrounded by forest high up the mountain must have been some life for the only son & eldest of several children with his parents.  Your resourcefulness reminds me of him.    Mahalo for the video.  Good luck on the rebuild of the heater.

I did something like this in about '76 with a horizontally mounted panel make with 1 X 6, some cardboard, salvaged galvanized sheet and fiberglass insulation.  The sheet metal was spaced equally from top and bottom and air was blown over the top to keep the clear plexiglass cool, and down to a "diffuser" at the bottom where it would flow up the back.  I had 2 rooms with windows 6 ft. apart, so I mounted insulated wood ports in the windows and just had a fan in one room and blew heated air into the other.  Worked great.  With a circulation fan blowing from the "hot room" down a hallway I could keep my house warm on even 30 degree sunny days.  No backflow with the fan off because both ports were at the same level. Just as an experiment I set a 1 kW heater in the "hot room" and it would not maintain temperature as well, even running continuously.

For moving air cheaply. Most of these blowup yard decorations, like Santas and Jackolanterns, utilize a 12V fan powered by an inline voltage transformer that plugs into 120V. They move air well! Designed to push air not pull, incorporate into the intake side to push air through the heater. I've also seen them used for ventilating areas like RVs and tents where they aren't in an environment of super heated air.

This was a very good & honest review, thank you!