Solar-powered solar-heater

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That sounds redundant doesn’t it? I don’t know, maybe, but I don’t think so. See it’s solar-powered heat, the sun heats up the heater and the fan blasts (well…I’ll get specific on that later) the heat into the room.  The fan is solar-powered as well. So using the same sun, but for two different parts.

OK, so here is how it works: The sun heats up the large black “box” while simultaneously charging the mini-solar panel. The mini-solar panel makes the fan turn which blows the hot air from the box into your room. Makes sense, right? I made this for about $35.  Perfect for me – nice and cheap!

I will share what I would do differently first so you can decide how you want to proceed with your own.  Be sure to share your stories, I am eager to hear all about them! First thing is to be sure your fan is powerful enough to blow the hot air where you need it.  I salvaged my fan from a treadmill that no longer worked. It just isn’t strong enough to blow the hot air far enough.  I’ve seen some fans on end-of-season clearance, I expect to replace mine with one of those, fingers crossed, for about $5-10. Totally worth it. Design wise, I would plan a better top plate for connecting/covering the fan to the box. It works, so it’s functionally fine, just a little lot ugly.

Now to get started here is what you need I used:

  • Random piece of plywood, any thickness, mine is 1/2″ thick (free, recycled from a different project we had in our home)
  • several tin cans I have almost 50 (25 larger cans, 20ish smaller cans that easily fit inside) (free, lots of soup! Progresso and Campbell’s)
  • scrap 2″x4″ ‘s. (free, had them around)
  • black spray paint, optional ($6)
  • black plastic sheeting (or garbage bag, though mine is thicker, .4 mil)
  • fan (free, from old treadmill)
  • solar top from a walkway light fixture ($3)
  • aluminum dryer hose semi-rigid ($10)
  • hose clamp ($3)
  • duct 6″-4″ reducer ($8)
  • 4″ plastic drain cover ($5)
  • toggle switch ($3)
  • 2 pieces of screen (4″x4″ each) (free, had it from a recently torn screen)
  • assorted tools, like: *safety goggles*, saw, cordless drill, sheet metal cutter, screws, 2″ hole drill bit, 1/4″ drill bit for can holes, staple gun, staples, solder gun, solder wire, electrical tape, packing tape or duct tape.

 

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Here is the plywood we had in a closet that was renovated a few months back. I kept it thinking I could make signs or something with it, but it will certainly suit me for this project. I removed the extra pieces leaving me with just plywood.

From this piece I made the base, a 1″ strip (details later), and a 8″ square to attach the fan and duct reducer.

 

 

 

 

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After cleaning up all the soup cans I drilled 4 holes in the bottom of each large can (3 in the small cans) using a 1/4″ metal drill bit.  The small cans stay in the large cans in the box. Other plans I’ve seen do not utilize the additional cans, but I figured more metal would generate more heat. You can decide for yourself. The size of the box is determined by the size of the cans.  I didn’t measure anything. If you have more cans, you can make your box larger. It can be made smaller if you have fewer cans, just don’t expect as much heat.

The holes allow the heat to escape the can and travel up and into the house. Other plans I’ve seen show removing the entire base of the can…not sure which works best.

 

 

 

 

 

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Laid out the two side and the bottom pieces of 2×4. PERFECT! The width fits 5 cans. Had enough cans to go 5 high. Be sure to make the box slightly taller than the cans to allow for air flow. To be sure there is space between the cans and the bottom I added a 1″ wide strip of plywood about an inch from the bottom of the box, then allow an extra inch at the top. Cut all the wood to size.

 

 

 

 

 

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After screwing all the pieces together I drilled a 2″ hole at the bottom and top, affixing the squares of screen on the bottom opening (one inside one outside, overkill perhaps, but I don’t like bugs inside the house.)

Before inserting the cans, screw the 8″x8″ square with a 2″ hole to the 2″ hole at the top of the box.

The cans are placed open end down inside to rest on the 1″ strip.

Spray paint it black. This step likely isn’t necessary. Many of the solar heaters I have seen use a glass across the front of the box, so having the contents be black attracted more heat. Since I used black plastic, the heat is already being attracted.

Then staple the black sheet plastic to the front. My cans basically stay in place, but at some point I *may* remove the plastic and wire the cans in there tighter somehow. Be sure not to cover the bottom hole.

 

 

 

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Meanwhile, inside, I remove the base from a solar pathway light. It had been charging outside. You can see the light is on. Unscrew the cover to reveal the guts. This proved to be the trickiest part for me, having extra hands would be helpful here.  I soldered the fan wires to the ends of the battery compartment.

***CAUTION: depending which wire you attach to which end of the battery will reverse the direction the fan blows…don’t have your heated air blow back into the box. 😉

I’ve also realized since assembling this that removing the light will be better for saving battery life. The light goes on in the dark, so the battery might not have enough power to get it going once the sun came back up.

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That’s about the time I figured having a toggle switch would be useful, too. After the sun goes down I don’t want cold air blowing into the house…have to be able to turn off the fan. Can you see that it’s connected and spinning?

 

 

 

 

 

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See the fan at the top over the 8″x8″ square, off to the right are the wires for the toggle switch and the solar panel. Just wire in the toggle switch between the fan and the panel, use electrical tape on the connections. Secure the solar panel to the box in a way that doesn’t block the sun. Tape should hold it well enough.

 

 

 

 

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In front of the box you can see the duct reducer. To be able to affix it to the 8×8 square I used sheet metal cutters to flare out the side, making tabs to be screwed down.

Behind the box is the duct hose. I chose the semi-rigid because the price was the same, if one was cheaper I would have opted for less expensive.  With that said, if it were windy, I would want it to remain secure, not blowing around, so semi-rigid is sturdier.

 

 

 

 

 

 

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Stick the drain cover to the end of the duct hose and begin enjoying some free day-time heat!

 

OK, yeah, there has to be more than that, huh? So the drain cover end goes in the house, but the rest stays outside. This means you need an access point, like a window.  This is where my plans need tweaking. Where it sits in this picture is the best place for sun, but there is no window. We had a pellet stove on the other side of the wall. The stove pipe opening is off on the right, that’s where mine will go. After we move, the best place will be the smaller bathroom with a south-facing window. I will measure the window opening, cut a bit of plywood to fit, making it tall enough to accommodate the hose.

 

 

 

Soooo, thank you for sticking with me on this winded description. 😉 It took me a couple weeks to make, only because of interruptions and other family obligations, but once you have the supplies, it can be a fun weekend project.

 

UPDATE: Well, before I had a chance to upgrade my fan, we replaced our bathroom vent fan exhaust hose with, you guessed it…my semi-rigid duct hose.  🙁  Hubby even used the clamps.  Back to Lowe’s for me…maybe I’ll just save myself the trip and order from Amazon.  😉

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