Ted Talks about Solar

There is always interest among people who either are or think they will be living off grid about solar

solar energy

It’s cooler now. ┬áKeeping in mind that solar collectors of the photovoltaic type are not particularly efficient (less than 20%), if you have places near your home that have full sun, heating is a reasonable alternative to photovoltaics as a major energy saver.

Some outfits lay the claim that you must have heat storage for an efficient heat collection system. However, to those outfits (such as ‘Home Power”), I am forced to state that’s BS in its most obvious form. To simplify the second law of thermodynamics, heat flows from hot to cool. It’s like a waterfall. The law also states specifically that anything you do to that flow between hottest and coolest will decrease the efficiency of the device. Logically, then, putting heat storage anywhere in the middle will cause the device to lose some heat.

It is, therefore, a much better deal to collect the heat and directly route it into your abode. As to heat storage, what the ‘outfits’ don’t seem to think or care about is that your house is filled with heat storage anyway: if your place is kept warm, all the furniture, books, tvs and whatnot you have inside will store up heat and release it in essentially the same way as any heat storage device, and that will be done directly into your living space, giving the most efficient storage possible. Works just like a Trombe wall, just with a bit less mass. [A Trombe wall is nothing more than a pile of rocks or such that is inside a dwelling; the mass absorbs heat and re-emits it into a cooler space.]

Since others have already fooled around with collectors, I’ll offer here a site that has a couple different styles of heat collectors, the tin can type and the screen type. This site also has data suggesting the more efficient one, and how to build both. With some of these you can keep your place fairly warm. The site is here:

DIY Solar Air Heating Collectors: Pop Can vs Screen Absorbers

DIY solar air heating collectors are one of the better solar projects. They are easy to build, cheap to build, and offer a very quick payback on the cost of the materials to build them. They also offer a huge saving over equivalent commercially made collectors.

Two of the more popular designs are the pop can collector and screen absorber collector. The pop can collector uses columns of ordinary aluminum soda pop cans with the ends cut out. The sun shines on the black painted pop cans heating them, and air flowing through the inside of the can columns picks up the heat and delivers it to the room. The screen collector uses 2 or 3 layers of ordinary black window insect screen as the absorber. The sun shines on the screen and heats it, and the air flowing through the screen picks up the heat and delivers it to the room.



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