Solar hot water - Thermosiphon

With enough time on your hands its possible to make water go round and around with the power of sunshine.

If you connect one end of a hose to the top of a container of water and connect the other end to the bottom of the container, you will have made a bucket with a loop of hose.

If you fill it to the top with water, shade the end of the hose that is attached to the bottom, and drag the entire contraption out into the sun, you will have made a solar powered thermosiphon.

A thermosiphon is better than a bucket with a loop of hose attached to it.

Because hot stuff rises, the part of the hose that is exposed to sunlight will make the water inside move up. Once the water moves up, some water in the bucket moves down. The water cycles around for as long as the device is in the sun.

The best part is, when the hotter water gets into the container, it rises to the top. This means that its the coldest of the water that flows back out into the hose, and the hottest water remains in the container.

This also means we have collected some solar hot water. Not much and not very efficiently yet, but we are on the right track.


  1. Very simple theory. Why didn't I think of it before?

    Was looking into a solar oven to play around with in Spring/Summer.

  2. I'm researching like a madman here. I had no idea how much potential there was.

    It(almost) makes me wish I paid attention (a bit) at school :)

  3. Well, I'm enjoying all your facts and figures here than the lessons I had in school years back! Not that I enjoyed science, but these experiments just make the theories come alive!

    Keep it up!


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