DIY Soda Can Solar Heater

Soda can solar heater, image from Hemmings Daily.
If you're looking for something to do as the temperatures drop away, why not give this passive solar soda can heater a try? All you'll need is some black spray paint, a bunch of empty aluminum cans, some 2x4s, and a few basic tools.

The solar soda can heater works by bringing in cool air from your home, garage, or shop through an intake hose at the bottom of the unit. Air rises through the system, which is warm from absorbing sunlight. Air comes out the top and back inside through the outtake hose—some bloggers are reporting at as much as 120 degrees hotter than when it entered!

We found a few variations on the design from Hemmings Daily, Fair Companies and Instructables. Here's the basic gist; write to us with your variations and photos on the project! And yes, it works: There's even a Canadian company, Cansolair, Inc., selling the things.


Materials
  • 240 aluminum cans
  • 3 - 8 ft. 2x4s
  • 4 ft. x 8 ft. x 1/2 in. sheet of plywood
  • High-temperature silicon
  • 4 ft. x 8 ft. sheet of Plexiglas or Lexan
  • A can of heat-resistant flat black spray paint.
  • Plastic tubing
  • Drill Press with wide drill bits
  • Screws
  • Optional Air Blower (consider a solar-powered unit)
Instructions
  1. Construct a wooden frame out the the 2x4s, approx. 4 ft. wide x 8 ft. high x 3 1/2 in. deep. 
  2. Cut a piece of plywood this size and nail it to the back of the frame.
  3. Drill a hole in the top center of the frame - this is where you'll connect your outlet hose.
  4. Drill a hole in the bottom of the frame - this is where your inlet hose will be connected.
  5. Drill large holes in the tops and bottoms from all the cans except for 16 which will be on the bottom row.  For those, drill the holes in the tops and sides.  Caution! Aluminum cans are sharp - use heavy work gloves or other means to hold them in place as you cut the holes out.
  6. Start placing your cans into the frame.  Create 16 columns of 15 cans each.  Stack them one at at time, sealing them together as you go along.  Make sure the ones with side holes are on the bottom row.  Allow the silicone sealant to cure.
  7. Spray the cans and frame with the heat-resistant flat black paint.
  8. Cover the frame with the sheet of Plexiglas or Lexan.
  9. Cut holes in the side of the building that line up with holes in the top and bottom of the solar panel.  Air will be drawn from the building through the lower hole, which should be just above floor level, and be returned through the upper hole.
  10. Mount the completed panel on the exterior wall of the home.  Alternatively, you might mount the panel in a separate frame that will allow it to be tilted more toward the sun for better exposure.
  11. Install the blower at either the inlet or outlet.  This is not essential, but will increase the efficiency of your solar heater.
This unit allows air to flow all around the cans as it moves through the panel. A more efficient design will force all the air through the inside of the cans.  This will also avoid exposure of the air to the black paint.



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Nicole Caldwell

Nicole Caldwell is a self-taught environmentalist, green-living savant and sustainability educator with more than a decade of professional writing experience. She is also the co-founder of Better Farm and president of betterArts. Nicole’s work has been featured in Mother Earth News, Reader’s Digest, Time Out New York, and many other publications. Her first book, Better: The Everyday Art of Sustainable Living, is due out this July through New Society Publishers.