Solar water heater

Did you know that the amount of energy radiated by the Sun in two weeks exceeds that of all the coal, oil and natural gas reserves on Earth?

The heart of the heater is the collector, how can you build it?


  • Approx. 2-3 m of flexible black tubing.
  • A sturdy, rectangular box, approximately 40 x 50 cm.
  • Black paint or a black coating for the inside of the box.
  • Glass to cover the box.
  • A clamp.
  • Two buckets or cans.
  • Two thermometers.


  • Paint or cover the inside of the box in black.
  • Make two holes to pass the tube through on one side of the box.
  • Wind the tube concentrically or snaking inside the box, but leaving a few centimeters of tube on the outside.
  • Place the glass on top of the box.
  • Place the buckets at different levels, under the ends of the tube, and fill the one that will be the inlet bucket with water.

Now that you have the collector, place it in a sunny spot, take the outlet end of the tube, and suck in the water until it circulates. Finally, place the clamp in such a way that it does not let the water fall in a jet, but drop by drop. Measure the temperature of the water that comes out after a while.


What happened to the water temperature? ________________________________________________________________

What is the difference between the water temperature in the inlet and outlet bucket?

Why do you think water is heated? What property of energy makes this possible?

What if it is cloudy?

What factors (variables) do you think may influence the heating of water to a greater or lesser extent?

  •  Perhaps the speed at which it flows through the tube? Try increasing or decreasing it by exerting more or less pressure with the clamp, what happens?___________________________________________________________________________      ________________________________________________________________________________________________
  •  Temporal factors such as time of day and season, or meteorological factors such as clouds? Do the test at different times and in different circumstances - what conclusion do you draw? ________________________________________________________________________________________________      ________________________________________________________________________________________________
  •  Assuming you live in the northern hemisphere, which way would you orient a solar collector on your house for maximum efficiency, N, S, E or W? Why? ______________________________________________________________________      ________________________________________________________________________________________________
Access to the best


on Energy and Environment
Go to resources