Free Heat From the Sun
Free heat from the sun is possible. I have built it and I have seen it work since the fall of last year. It's called a solar heater window box. Put it in a window that is getting full sun and in less than an hour it is pumping out free heat with just the power of the sun and direct sunlight exposure. 120F or more of free heat. These solar window boxes just don't heat up air but they have a built in system that heats up and holds the heat longer giving you additional heating when the sun starts to set.
Anyone can put a bunch of soda cans or beer cans into a box and call it a solar heater. Go for it, try it. The main problem with a soda can heater is the connections between all of the cans. You can not guarantee that the seal is perfect and will last.
Free heat is possible with just a two foot by two foot window sized box that heats up the air inside your home and pumps out the free heated air from just the power of the sun for free. All you pay for is the power to run a 3 watt fan. Ergo free heat. Check out Sun System Designs video and feel free to spread the word and let us know what you think. You can find more info at sunsytemdesigns.com or visit them on facebook by searching for Sun System Designs. Putting a like on the main page would be greatly appreciated. Go solar, go green, and let your children and grand kids know that sometimes the energy you need to live does not have to come from fossil fuels. It is right over their heads.