Solar energy is a renewable resource that can be used in various ways. One of the most common uses is heating water. Have your students make their own solar collectors and experiment to see which ones heat water most effectively. Students can work in teams or individually. But keep in mind that each collector created will need to be exposed to bright sunshine, preferably outdoors or in south-facing windows.
- Cardboard boxes (no more than about 10 cm deep–the size of a small shoebox should be fine)
- Aluminum foil
- Black poster paint and paintbrush
- Small, sealable heavyweight plastic bags (one for each box)
- Laboratory thermometer(s)
- Duct tape or other heavy-duty tape
1. Cut pieces of aluminum foil large enough to cover the bottom of each of the boxes.
2. Using the poster paint, paint half of the aluminum foil pieces black.
3. Once the paint is dry, tape the foil onto the bottom of each box. This is the solar collector.
4. Next, fill each plastic bag with approximately one cup of cold water and seal tightly.
5. Tape a bag of water to the foil in the bottom of each box.
6. Take each box outside and place in bright sunshine. You will probably want to prop the boxes up against a wall or a board, so that the water can absorb the maximum amount of solar energy.
7. After one hour, carefully remove the bags of water, unseal them partially, and insert the thermometer. Assign one student to record the temperatures from each collector, noting whether the surface of the collector was painted black or not.
8. Discuss results with students and ask them to explain why most solar collectors are painted black.