Solar Water Heating

  • How could the sun be used to heat water?
  • What properties improve or hinder performance?

Recommended Items:

  • Different types of tubing (metal, plastic, etc.)
  • Thermometer
  • water pump
  • water reservoir or basin.

Concepts used:

  • Color, Materials, Passive solar, Solar water heaters


Solar water heaters rely on the absorption of sunlight by dark tubing through which a liquid, like water, flows.  As the sunlight heats up the dark tube, the heat is radiated (or transferred) to the liquid inside the tube, making it also get hotter.  This process can be used to heat water for a home.  Because, different types of tubing can heat up faster than others, it is important to select the correct material for the tubing.  Another factor affecting heating is the volume of water that is being heated.  Larger volumes of water will take longer to heat.

To perform this experiment, take different types of tubing (PVC, Copper, flexible tubing) with the same inner diameter and let them heat in the sun.  Record the temperature of the tubes several times throughout the heating process to help determine which tube heats best. Another good bit of information to look at is how long it takes the tubes to cool down in the shade.  In addition, it is a good idea to test different colors, to see which color tubing gives the highest temperature. Take different painted pieces of tubing and measure the temperatures after they sit in the sun for a period of time. Then design a water heating system using the best tubing by making a tubing system and laying it in full sunlight and then running water through various lengths of the tubing system and recording the temperature of the water that goes into the solar water heater system and comparing that to the water temperature as it leaves the solar water heater system.

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