How to Make a $5 Solar Water Heater From Junk Fridge

backoffridgeI mentioned in an article last summer that most Israelis have solar water heaters on their rooftops, and thus they save a lot of energy during the summer. In fact, the idea of heating the water in a boiler is not new, I had more than a dozen showers in my grandparents’ backyard, during some hot summer days in my childhood.

One simple way of making water hot has been perfected by a blogger on, and it relies on a simple and easy to find piece of junk: an old refrigerator!

Other components are: wood, for making a frame, glass (not plexiglass), hoses, a rubber door mat, a reflexive aluminum foil, scotch tape and glue, or silicon. Eventually, you’re going to need some screws.

Because it’s black, the refrigerator radiator heats faster than other materials. This also happens because of its tightness. The inventors who made this “instant” solar water heater want to make another one, that transports the water by thermal convection and recycle it, until it reaches the desired temperature.

The entire solar water heater project costs less than $5 and can save you of a lot of electricity, reflected on your bill.

It’s easy to do. You may go to their site or watch the gallery below, because it’s self-explanatory:


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These guys like us. Do you?


  • homeschoolscienceteacher

    @titus Use an old car raidiator instead safer and and a much larger metal mass for heat absorption.

  • The Wizard of Cake

    But what you forget is your letting free cfc’s as soon as you undo the freezer radiator.

  • david henry

    The foil reduces the efficiency of the heater. You want ABSORBTION, not reflection, of the solar energy.

    • Yes, but part of that reflected light goes into the pipe. Without the foil it would otherwise get lost, by heating the support.

  • Is it really working?

  • Just love this! I wish I had the ingenuity and ability to transform an outmoded product to a useful pieced of equipment. I often have flashes of ideas, but then lose sight of when it gets down to the physical completion and execution.

  • cory

    the sun causes global warming………not freon…..

  • please do not use refrigerator parts: when you cut the tubing the refrigerant (freon) will be released into our atmosphere causing global warming…

  • I believe, that a big barrel with a water on the sun (on the roof) – after the hot day – can make more hot water then this 🙂

    • First of all, you need efficiency in heating the water. What greater efficiency can you have than that of a thin, black pipe? The hot water in the barrel gets hot after a few hours (I know that from experience), but this kind of setup heats it almost instantly. For example, leave a hose (not a black one) in the sun for 2 minutes. I guarantee you won’t want to bathe in that hot water from it!