The first thing I noticed was how much the clear plastic cover bowed out. Between the fan blowing air into the panel, and the heat causing expansion, the plastic was bowing out probably 2 inches. Additionally, the landscape fabric which was stapled in tight, was saggy like an oversized sweatshirt.
When I got home about 6pm, I checked the temperature of the garage, it was 50 degrees still. It normally follows the outside air temperature pretty closely, so being 10 degrees warmer than the outside 40 degrees is pretty good. I desperately need to insulate the garage, if only to stop it from being so drafty!
I want to find a 15 watt, 12volt PhotoVoltaic panel to run a computer case fan I have. At that point, heating the garage would become free energy. $80 seems to be the going price for the solar panel. An alternative would be a thermoelectric generator, but they aren't marketed for this application, so it's really hard to read the specs to figure out what I would need. It appears that I would need $60 worth of those (3) in order to work. These would also bleed heat out of my panel, so they are a 2nd level option.
I still need to trim out the panel, which would make it look better as well as seal up the plastic on the front face.
In album $7 Garage Hot Air Solar Panel (40 photos)