The lab experiment we completed in the last class involved the use of a photovoltaic cell to determine the voltage created by an outside light source. In order to complete this lab, my group used the computer-connected solar cell aligned with a ruler to measure the distance from the designated light source, which in this case was a miniature flashlight.
There were two parts to this lab: the first portion required us to shine the flashlight directly onto the panels of the solar cell from different distances (as measured by the ruler), thereby allowing the computer to calculate the differences in voltages for each trial. According to some advice we learned before this experiment, the further away the solar cell moved from the light source, the smaller the voltage amounts should appear on the computer screen.
As we began this part of the lab experiment, we began to notice flaws in our equipment that could affect our results. The first time we ran the voltage-calculating program on the computer to determine the charge input from the solar cell with no light source, we noticed that our numbers were significantly high despite the lack of light – apparently, the numbers were supposed to be lower than the ones we received, which ranged between .10 and .20. For the next four trials, we ran the program each time by moving the solar cell back in increments, starting at 1 centimeter, moving to 10 centimeters, then 20 and finally 30 centimeters. Our odd results indicated to us that something in the equipment was not allowing the program to produce accurate results, as the voltage numbers fluctuated from high to extremely low, then crept back up again. Likewise, our supposedly faulty results were also skewed in the troublesome Excel sheet, and we had no choice but to redo our entire experiment
For our second round of trials, we did not begin with the lack of light source, and jumped in to using the solar cell at 1 centimeter away from the flashlight for the first trial. As Fig. 1 evidences, the voltage results ranged from .5 to .6, which are considered a normal high for the light source shining so close to the solar cell panels. However, for the second trial, our fears
from the faulty first experiment came back as the results from 10 centimeters away ranged from .2 to .3, followed by an increase to .3 to .4 when the solar cell was moved 20 centimeters away. Finally, as Fig. 1 shows, the voltage stayed constant between .3 and .4 even when the solar cell was 30 centimeters away from the flashlight. At the end of this portion of the lab experiment, we were instructed to calculate the average voltage for each trial and create a scatter chart with the data; looking at Fig. 2, there is a clear inconsistency in our result averages. Logically, the numbers should
have gradually decreased as the solar cell moved further away from its light source; considering our extreme caution in the prevention of human error for this second round of trials, we can only conclude that flaws in our technological equipment could have yielded such odd results.
The second part to the solar cell lab involved the use of thin, colored filters to be placed in front of the light source to alter the light absorption of the solar cell, which had to be kept at a constant distance from the flashlight. Choosing a distance of 10 centimeters, we first placed the red film in front of the flashlight, ran the voltage calculation program, and watched as the results ranged between .3 and .4, the average for which we calculated to be approximately .36892. For the next trial, we used the green filter, which produced voltage results between .4 and .5 and yielded an average of
.49851. The final trial using the blue film gave us results mainly in the .4 range, dipping down to .39 at only one instance. The average of this trial was .4202. Concluding with our experiment, we graphed the average results of this portion of the lab into a bar chart, which is evidenced in Fig. 3. The blue and green filters yielded higher voltage results than the red film as can be seen in the graph, concluding that the darker red absorbs more of the light to make it incapable of reaching the solar cell.