Through the water in the sky

I had a conversation last Friday about solar hot water and it seems like a really feasible way to get hot water into the Microhouse.  Basically there are two options:  one involves a pump that continuously pumps cool water through the panels on the roof that warm the water when the temperature drops.  That one involves more energy.  The second option involves a closed system with basically antifreeze that circulates heating up a copper coil that conducts heat into a water tank (that would be well insulated).  This way can use the water to heat the house, although we will have a wood stove.  I dont know which one to go with, but I think they are the best option, and can be rigged up with materials that we have now or will eventually have.  They seemed pretty simple in conversation but when you Google it, they get pretty complicated.  More research is necessary…



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3 responses to “Through the water in the sky

  1. I think these systems demonstrate well how very simple, elegant ideas are hard to execute just *so*.

  2. Grant Wagner

    Solar hot water is a very interesting beast, with all kinds of trade offs between effectcy, cost, and DIYness.

    On the far cheap end is a batch heater. Put a water tank (one from a conventional water heater, shell removed, painted flat black) in a big box with a glass top, very insulated sides, and lined on the interior with something shiny. Two pipes go in, one for cold water in and one for hot water out. Simple enough, but its all manual control, and the temp of the water coming out depends on: amount of sun, relative temp of the sorounding air, time since it last filled, temp of the water going in, etc, etc, etc. AKA, enough fiddling will get it done, but “enough” is probably a lot more that you want to deal with.

    Then again, a basic solar shower bag stuck in a window is never that bad of an idea.

    At the high end is a system very similar to what you described, water stays in an insulated tank, an antifreeze mixture is pumped through a heat exchanger in the tank through the panel itself. When the sun doesn’t shine, the circulation pump turns off. The panels themselves are metal sheets in tubes in which all the air has been pulled out completely, making for a near perfect tranparent insulator. The down side is that these need a (relative) large amount of energy for all of the pushing arround of fluids and controllers to keep it all humming along nicely, as well as depending on manifactured goods.

    And of course, solar isn’t a constant, so you still need something for those days when the sun doesn’t shine.

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