Need some free heat? A break from your expensive utility bills? Here's my suggestion.
A Solar Air Heating Panel
This panel is 2’x5’6’’ It is 5.5” deep tapering to 3.5” on the sides. The polycarbonate sheet salvaged from an old tanning bed is the only reason a flat sheet wasn’t used. You could use glass, plexi or polycarbonate. The fan is from a computer power supply. The rest of the materials are new.
I bought some guttering downspout, two 1x4x6, one 1x6x8, one 4x8 sheet luan, 2 – 4” duct taps and some black caulking at Home Depot. I got 3 cans of high heat black paint, a quart of roll on primer and a cooking thermometer at WallyWorld. Got the 12v 7ah battery, the 12v solar panel and the fan thermostat online. I had various screws an such on hand.
Gather your material and find a nice place to work. Like this gravel parking lot
I routered the edges, it is not required.
Using a skill saw and guide I cut a channel for the polycarbonate to slide into down what would become the sides of the panel.
I then cut my sides and end to length and assembled the panel frame around the poly sheet.
Once I had the inside dimensions of the panel I cut my spacers for the collector tubes. I used a jigsaw to cut the openings and sanded them to the same dimensions. Also drilled 2 ½ holes on each side to allow enough air flow to eliminate any possible condensation in the panel.
I cut my downspouts into 52” long pieces. I then used two pieces to test fit the spacers into the panel to make sure everything would be square.
It looked good so I cut and added the luan back to the panel frame. I also cut in the intake and exhaust holes for the panel and installed the 4” duct taps.
Then using a step bit I put a 1” hole in the bottom of 55 pepsi cans. You have to make sure your cans are completely dry and shake out all the aluminum shavings after drilling. Easy to do, and it won’t rattle during use.
And then stuff the cans into the pieces of downspout. This is to create a heat exchanger of sorts. The aluminum downspout and cans collect the solar energy and transfer it to the air passing through and around the cans.
I then assembled the collector tubes and spacers and caulked them into place.
I drilled the hole for the thermostat at the top of the center tube and everything got a coat of primer and a couple coats of black high heat paint.
Once the paint was dry I added an adjustable fan thermostat. This is a close on rise stat. It turns the fan on at 110 degrees and off at 90 degrees. The fan is brushless, very quiet and rated at 106 cfm, this goes in front of the upper hole blowing out of the panel. I installed the battery in the bottom and connected it to the stat and fan. I also drilled a hole and installed a probe thermometer in the top side of the panel.
I intend to add a 12v PV panel to charge the battery as soon as Fed Ex brings it to me. This will allow the battery to be charged anytime the panel is in operation and the panel will be completely self contained.
I touched up the painted surfaces and once it was dry I put the poly panel on and set the solar air heating panel in the sun.
Today, Nov 3, 2010 here in KS it is mostly sunny, windy, and the ambient air temp was 57 degrees. This is the thermometer behind the bottom of the panel where the intake air would be drawn from.
It took just over five minutes for the panel temperature to rise enough to activate the thermostat at 111 degrees and turn the fan on. At 30 minutes the temperature had been stable for a few minutes and I didn’t think it was going to rise any more. It stabilized at 148!
The panel was creating a 91 degree temperature rise
and blowing 148 degree air out at 106 cfm. This would allow a complete cycle of the air in a 12’ x 12’ room in less than 10 minutes.
A solar air heating panel will definitely supplement your daytime heating and reduce your utility bills. Further testing is needed, but I suspect it would heat a small shed or hunting cabin by itself. If you have a south facing wall, you can use these.
My total cost with this panel was about $130.00