Overview

In order to test the self-cleaning feature of our solar panel buoy, we first placed the buoy outside in direct sunlight, then recorded the output voltage produced by the panel by unplugging the battery from our electronic system and taking measurements from the panel terminals. We poured ¾ c. of oatmeal on the panel to simulate bird droppings, then connected the battery and ran the cleaning system for one cycle. One cycle consists of the wiper blade moving from full extension on one side to full extension on the other side, then back again. After the cleaning cycle was completed, we unplugged the battery and recorded the output voltage produced by the solar panel. We wiped off the remaining oatmeal and ran the test four more times. Test data is shown in the table below. Initially, we were expecting to see the “Before” values to be significantly greater than the “After” values, however we did not observe this. To account for the unexpected result, we recorded the during voltage (output voltage produced by the solar panel while the oatmeal is on), to ensure that oatmeal actually decreases the performance of the solar panel.

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Analysis

After calculating the differences between the before and after voltages, we ran a normality test to see if the differences came from a normal distribution at a significance level of 0.025. With a p-value of .013, which is less than α=.025, reject the null hypothesis that the data comes from a normal distribution. Since the differences failed the normality test, and the number of trials is less than 30 (requirement in order for the Central Limit Theorem to apply), we bootstrapped the data. We took 5,000 samples, and we generated a 95% confidence interval for the differences: (-.06, .06). With this interval, we are 95% confident that there is no difference in the voltage before and after the oatmeal was applied and cleaned. This confirms that we were able to meet our metric that states: “The solar panel produces 80% of original output after oatmeal is applied and cleaned after one cleaning cycle.”

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