Science Fair: Solar Cell Efficiency

Science Fairs

Science fairs are a fantastic way of introducing the scientific method to kids and getting them excited about doing science! The goal of a science fair project is to pick a question, develop a hypothesis, experiment, and draw conclusions from the data that support or don't support the original hypothesis. A perfect way to put science in action! My 11 year old has participated in a science fair each of the last three years and is doing so again this year.

Solar Cell Efficiency

This year my daughter decided to test the efficiency of solar cells under different scenarios. We purchased a small solar cell and she grabbed a multi-meter to measure the output voltage of the cell. She tested the following.

1. Output voltage vs. distance from the light source. This was more a less a test to see if the solar cell was working properly. Obviously the closer the cell is to the source, the greater the output voltage. And that is exactly what she observed.
2. Output voltage vs. type of light bulb. My daughter compared an incandescent bulb, fluorescent bulb, and LED bulb of the same brightness (lumens) and measured the voltage output on the cell. Turns out the type of bulb matters, even when the brightness is the same. An incandescent bulb emits a lot more infrared light, picked up by the solar cell.
3. Output voltage versus light angle. This was the first of the real tests. How does the output voltage change as the angle of light changes? This plays an important role in determining how best to install industrial solar cells. She knew there would be a change, but is it a linear change with angle or another type of functional change?
4. Output voltage versus temperature. Admittedly I did not know how this one would turn out. My daughter hypothesized that the temperature of the cell would have no effect on the output voltage. After testing, however, she learned there's a clear change in output voltage with solar cells being much more effective when cold, compared to hot. Interesting!

The presentation of her project at the fair is coming up, and she is excited! This is her first year in the next division. Previously she was always in the elementary division and now she's in the middle school division with an opportunity to advance on to the state competition. Exciting stuff!