Over at Hemmings Daily, you can see how to create your own free heat using custom made soda can solar panels.
That’s right- recycled solar panels- using almost completely free materials.
Thank you so much, Vanessa, for sending this article over to me.
With some 2x4s and plywood you create a simple box to house the cans.
The box was then sealed using caulk. Holes then have to be drilled strategically on the cans.
Then you stack the cans appropriately so that the holes all line up and you do this with caulk.
Once that dries up, it’s time to paint the cans black so that they can absorb as much heat as possible.
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Click here to get better step by step instructions on how to create your own free heat using used soda cans.
Thanks again, Vanessa! I thought this might be a great DIY idea to heat a tiny home or a backyard shelter.
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This is a fine design because the elements are so inexpensive.
Having said that you might want to purchase a bunch of aluminum shavings from someone running a metal lathe. Wash the shavings before soaking them in black paint and tossing them on a screen to dry. The surface area of aluminum shavings is huge and as a consequence the heat they can gather is unusually great. Underneath the shavings a layer of black asphalt holds the heat and air passing through the box can carry the heat. Be careful and metal frames are safer as you may well capture so much heat that a wooden frame would burst into flame.
Good idea, Jim, thanks for sharing!
Nope, never had the worry that it would burst into flames as it never got hot to the touch. The hotter the air gets in the tube, the faster it flows upward, drawing cooler air in at the bottom. It’s still working today. The back of the ‘solar chimney didn’t feel warmer than the room temperature. I like the idea of the shavings, and will mull that over for another experiment I’m working on. I used pop cans because the nieces & nephews were so willing to provide them at no cost to me. However, where my system is permanently mounted in a window, the original posting was about a system that could be moved.
I made one of these back in the ’90’s, as an experiment (I live in Alaska). Set it in a window to see how much heat it would produce. Put a thermometer probe down one of the tubes. On a sunny day it got as high as 122 degrees before the thermometer went kaput. It got hotter than heck inside the room in my cabin because I forgot to include a method to bleed-off the extra heat. With this outside unit in the article, however, that wouldn’t be a problem. It did make it easier to shovel snow off the tin roof in winter time.
Wow, that’s genius. Thanks for sharing.
EXCELLENT find Alex!
Forgot to mention…Rustoleum makes a spray paint in ‘flat black’ that works best for coating the pop-can tubes (not as thick as enamel and transfers heat better). Also, since it was inside my cabin, I built a shelf out of hardware cloth (1/4 inch wire) to set the tubes on, then backed them with solid styrofoam sheets & heavy tinfoil for insulation. I drilled holes in the bottom for air flow into the ‘solar chimney’ from the roim, placing a sheet of mylar on the outside if the holes–this let the air flow into the tubes during the day, but prevented reverse flow at night when the sun went down. This was about 20 years ago, but I could find my drawings if someone is interested in building one.
Would be very interested in trying to build one if you can find your drawings. Thanks for sharing.
I’m away from home working on my latest project. Will post drawings when I return. The solar chimney was an idea that I read about in a magazine around 1988 or so. I scrounged all the materials–old single pane glass windows, scrap lumber, rigid styrofoam, hardware cloth, pop cans, etc–and only had to buy the black paint and heavy aluminum foil. It was an experiment and I didn’t want to spend a fortune on something that might not work. But it has–for 20 years, and is still in use today….with no maintenance, I might add. (Wish I could say that about some of my other projects).
i to would like a set of plans to build from. the price is within my means to build it. If its still working after 20 years, that’s all i needed to hear. thanks
I don’t know how to post pics and plans on this site, but if you’ll send me your email address, I’ll send them directly to you.
Most of the pop can solar heater plans on the internet are exterior units with means to pump air into the home. I have a sunroom and want to put a pop can solar heater in the sun room. I have found no information regarding the efficacy of having an internal unit. In your opinion would this work?
No, you would not need to have a solar furnace or solar chimney inside a sunroom or solarium. In your application, just including/installing more “heat-sink” materials into the room and then having darker colors in the room would give you significant gain. The sun striking those heat-sink surfaces (such as barrels filled with water or large rocks or sand or steel objects, all contained in something black that has a high specific heat index) would greatly warm your house and then radiate the heat over the night. I saw a house at 39 degrees north which is heated this way. It is a rowhouse with the back of the house facing south, with a 2 1/2 story glass greenhouse on the back of it. The greenhouse is sheathed in double pane untinted glass and it is super-caulked to prevent any airleaks. The owner covers much of the space with a tarp all summer. Inside the sunroom (which is outside the back of the house, he has large containers of water (55 gallon barrels welded together, 3 barrels high, strapped to the back of the house, and he painted all the bricks on the back of the house black. It gets REALLY hot sometimes, and he has to open other windows to dissipate the heat some days in winter. He can heat his whole house, even on cloudy days, most of the time at that latitude. What he does is opens the door to the basement and opens the upstairs back windows (both of which open within the sunspace) and the thermal column that develops does the rest. If I ever move back to snow country I will do the same thing. I’ll find a house with a 2 1/2 story south facing rear wall, and build the same thing that guy had. He rarely used any supplemental heat. At night he just closed the windows and basement door, or, left them open all night if the sunspace was superheated, warming the whole house all night sometimes. He also started his spring garden in the sunroom to get a head start on his tomatoes in the spring. When snow covered the whole two story wall of glass it did look weird…..like you were in an igloo until it melted, unsually the same day it snowed.
What I liked the most was the fact that his system wass completely passive and that it was outside the actual house…..no worries about leaks, broken glass, whatever, causing a compromise of the structural integrity of the house itself. And I liked that he had a nice, green, sunny, warm place to sit in the winter and read the paper.
I used a clothes dryer flex exhaust pipe. It is made of aluminum, very light weight, 4 inches in diameter. It is 40 feet long. I fully pulled the “accordian” shape out of it, and made turns up and down inside the enclosed panel. The pipe turned to have an intake and a discharge on the back of the box. I got a double glazed double sized fixed glass window (untinted) from ReStore and set it on the box sized to fit. The sides and back of the box were made of construction insulation board with aluminum skins on it. I painted the whole box interior flat black high temp paint (intended for painting barbeque grills).
The box works well and produced 160F air with an ambient temperature of 58F at the autumnal equinox (Sept 22) at 39 degrees latitude, in full sun. A thermal coupler turns a large computer fan on and off (circuit closes to turn it on at 85F and opens to turn it off at 68F). No precise idea how many cubic feet of air are flowing through the box, but I estimate that the box will heat 300 or 400 sf of living space nicely.
Saw a similar one heating a mobile home in north Florida; the owner heats the mobile to 85F if he can and then “coasts” overnight, turning on his conventional furnace if he must toward dawn. An 85F mobile home is very warm to me, and I would have to live naked with a ceiling fan on me, but he is an old codger and feels cold a lot of the time….he says it helps his joints to get that warm.
I could see someone making a smaller version of this….maybe 3″ thick and 24″x48″ and mounting on the side of their van or trailer in the winter. I’d use 2″ flexible exhaust pipe and wrap it with rubber foam pipe insulation. One opening near the top blowing across the van and an input down low will help re-circulate air. You could always put a gate in each end or use the mylar flap mentioned previously to automatically shut it off when it gets dark. It could be hung up when parked and stored inside when traveling.
Another idea I’ve had is putting a mini-“sun room” of sorts on the side of a cargo trailer. The wheels and fenders almost ALWAYS stick out past the sides of these trailers. Shelves could be made with aluminum expanded metal screen and mounted so they won’t stick out past the fenders, and plexiglass could be mounted to cover that, leaving a solar heater or greenhouse about 6-9″ wide along the side of the trailer. A small hole at the bottom and one at the top would allow plenty of air flow. Smaller holes allow the air to heat more, while larger holes allow more flow at lower heat. Air dampers could also be used for this, and I would adjust the air holes for the size of the trailer.
Did I mention “greenhouse” in there? I think some veggies would grow throughout the winter if you chose them wisely.
Fantastic! You sound like a budding inventor. I’ll bet these would work. Why don’t you draw up your plans and try them out? I’ve been looking for a way to avoid the cost of heating my RV. Your passive solar sounds like it would work on a stationary RV.
YouTube is full of diy and test videos showing these in action. They are easy to make in a variety of material choices. All seem to be effective at generating heat. The computer fan is a nice touch for larger units. One I saw was hooked to solar for the fan too. You may not be able to heat completely with these, but any heat it gives is heat you don’t have to buy!
Just search YouTube for “pop can solar heater” it will be worth the time. There are some great tips in many of the videos so take notes and make what works for you.
Oh, ya there are videos on YouTube that shows you how to construct this thing of different sizes.