Solar hot water - Greenhouse

Anyone who has left a hose out in the sun on a hot day will know how much heat its possible to collect. Collecting heat on a hot day is easy. What we need to be able to do is collect heat when there isn't much around. One way to do that is to flatten out your hose to increase the surface exposed to the heat. The downside to that is you also increase the hose's ability to radiate or lose heat.

What we need is a flat, large surfaced hose that's insulated to prevent heat loss. Unfortunately what we also need is a big flat hose that's exposed to the sun and isn't insulated in any way. In fact what we need is a big flat hose that's both, a conductor of heat, and well insulated.

Some years ago in Rome, someone accidentally mixed a flux of some kind into their beach party's fire. The same thing probably happened in China as well. Some time after that, people started making glass. Others may have a slightly different or more complex  history of glass, but I'll leave it to the reader to decide on their preferred history.

Normally when the sun's radiation hits something it gets warm. If the object becomes warmer than the surrounding environment, the object starts to radiate energy to share the warmth. Heat and light (and microwaves, and for what it's worth, puppies and beer) are all basically the same stuff. There is a very cool characteristic that glass has. Light, unlike puppies and beer, to a large degree can pass through glass. Once it hits something that it cant pass through it is either reflected away or is absorbed. If it's absorbed it is absorbed as heat. Normally when something outside is heated, the heat radiates away and warms up the air or whatever else is around it. This air then rises and disperses away. But you can use glass to stop that hot air escaping, or at least to slow it down. If you used glass in this way you will have built a greenhouse.

It seems to me, in order to make a solar collector, what we need here is some kind of big flat matt black greenhouse hose.

I think I understand the main principles involved here so It's time to do some experiments.

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