In this activity, you will explore how a solar water heating system with a circulation pump might function.

1. Attach each of the two pieces of 10 mm tubing to the ends of the 6 mm tubing extending out of the solar water heater panel you made in the first part of this experiment.

2. Attach the 10 mm tubing at the top of the panel to the water pump

3. Place the water pump and a thermometer into a beaker and fill the beaker with water.

4. Place the solar water heater panel on the component box so that it is about even with the top of the water in the beaker. Insert the end of the 10 mm tubing from the bottom of the panel into the beaker so that the water has a complete pathway for circulation. Assemble a solar cell, junction box, Power Out cable, coaxial adapter, and DC coaxial power jack, as in the Sun Tracker activities. Connect the alligator clips to the pump connector wires.

5. Unless your sun is exceptionally strong, the pump will probably not work. Don’t worry! All it needs is a bit more electrical power. You can provide this by using the other two solar cells in the backpack. Connect them to the junction box as shown, and the pump should start up.

Note: Once the water starts to circulate, you will probably notice a lot of air bubbles in the tubing. As the water flow stabilizes, these bubbles will disappear. Once this happens, you may have to add more water to the beaker. The pump should be covered with water at all times.

By the way, there are many other ways to power the pump. We used three solar panels, but another DC source, such as a battery pack of four AA batteries or a GoGo board, would work just as well.

Once you have your system working, observe its behavior periodically over an hour or so.

Stir the water in the beaker gently with the thermometer each time before taking your water temperature measurement. Use this table to record your data.

We started out with water at 28ºC and a temperature of 36ºC inside the panel. In less than an hour, the water temperature was 40ºC and the panel temperature was 55ºC.

Extension

Automate your water heating system using the GoGo board. When the water temperature is cooler than desired, turn the pump on. When the water has reached a desired temperature, turn off the pump.

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