A hot air solar panel is probably the most efficient way to draw energy from the sun. The sun has about 300 watts of heat per cubic meter. If you put stuff out in the sun, it gets hot. A panel like this is simply a contrivance to allow that heat to get moved to somewhere where we want it.
My panel works by putting black landscape fabric out in the sun. This fabric is in a long, insulated, shallow box with a clear vinyl front. The fabric is touching the back on one end, and touching the front on the other. The only way air can go from one end of the box to the other is to pass through the fabric. This will cool the fabric, warming up the air. By putting a fan in the garage blowing into the panel, the panel will recirculate the air into the other end of the garage, heating the garage.
I started with an idea of how I wanted it to turn out and just winged it as I built each step as to how the next step will be built. That is a lot of the fun of using salvaged materials.
I am using a 4 inch inline duct fan I got on freecycle to blow air through the panel. Ideally, I would like to get a solar panel to run the 12v PC case fan so the whole thing counts as 'free' heat. The photo-voltaic would cost as much as the whole hot air panel would if I had bought all the materials new!
I need to add some strips to help hold the vinyl tight against the frame so it doesn't leak air. I am going to make this look like window trim so the whole contraption doesn't look bad.
I put an indoor/outdoor thermometer in the garage with the outdoor sensor in the hole for the air returning to the garage. This should tell me how hot the air is coming out of the panel.
If this works well, I plan on building a more permanent installation. The garage is old, aluminum siding right now. I want to re-side the garage to match the house in a couple of years. At that point, a permanent, glass, panel will be made that will be built into the garage.
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I seem to have misplaced my automatic board stretcher, so I needed to manually create notches so I can splice short boards together to make long ones.
If you squint hard and look some other direction, you would never know that I spliced these boards together.
I’d found some sort of black shrink wrap in the basement when I bought the house. It seems to work well enough to make a back for the solar panel.
The shrink wrap sticks to itself so it forms an air tight back. Starting to put the cross members used for hanging the panel to the garage wall.