Last year my brother made a project that used a solar cell to convert light to electricity. It was wired to a buzzer that would sound to show how strong the light was. When he tested it, he pointed it directly at the light. This made me think about the solar panels that are used on buildings to make electricity. I wondered what position was best for getting the highest levels of electricity.
My hypothesis was that a solar cell that was placed level to the ground and pointing straight up at the sunlight would show the highest output of electricity. To test this I decided to compare this with a solar cell that was at a 45-degree angle and one that was at a 90-degree angle.
I got a wooden base and three dowel rods. One dowel rod end was trimed to a 45-degree angle. My father and I drilled holes in the base and put in the dowels. Then I painted the base and the dowels black to cut down on reflected light. Two screws were put in front of each dowel rod.
Two wires were soldered, one red and one black, to each of three solar cells. Then we used a hot glue gun to attach the solar cells to the dowel rods. The first was set at a 45-degree angle, the second was level on top of the next dowel, and the third was at a 90-degree angle on the front of the last dowel.
The wires coming from the solar cells were attached to the screws in front of it.
My first test was done on a partly cloudy day and it was hard getting a steady reading. After that I only did tests on clear, sunny days.
I used a digital multimeter to test each cell. I did this by touching the red lead to the screw with the red wire and the black lead to the screw with the black wire. I took readings for all three solar cells in this way.
I recorded the date and time along with the readings for each solar cell. I used a Web site called Your Sky (http://fourmilab.to/yoursky/) to find out the angle of the sun when I took the readings.
The results between the 45-degree angled solar cell and the level one were the highest with the angled one averaging just a little higher. Both of these were better than the one at a 90-degree angle. The highest reading for the solar cell at a 90-degree angle was lower than the lowest reading for either of the other two.
In two tests the level solar cell tested higher than the 45-degree solar cell. The first time was a partly cloudy day and I had trouble getting good readings. The second time it tested higher was at noon.
One time the 45-degree solar cell and the level solar cell gave the same test results. During that test the sun was at a 46-degrees, so both solar cells were getting sunlight at almost the same angle.
Tests done later in the day when the sun’s altitude was below 10-degrees showed the widest range of results.
My hypothesis that the level solar cell would have the highest readings was incorrect. Although it tested high at noon, overall the 45-degree solar cell averaged higher throughout the day. I was surprised at the results and think that the level solar cell might still do better if the tests had been done closer to the equator.
I would have liked to have taken more readings but I had two problems. In the beginning my testing was delayed when my cat knocked the test equipment off a table and broke one of the solar cells. Rainy or cloudy weather also kept me from testing on some days.
My conclusion is that for my latitude (N85.491845), the solar cell fixed at a 45-degree angle was the most efficient at converting sunlight to electricity. My second conclusion is not related to the experiment itself. It is that I shouldn’t leave test equipment with dangling wires where my cats can reach it.
