Results and Feasibility

Experimental ResultsExperiment

Before we tested the actual output of the solar cells out in the sun, we conducted preliminary experiment in the laboratory room with DC power supply equipment and measured the voltage and the current with a bench-top digital multimeter. With our voltage regulator circuit built on a breadboard, we supplied voltage to the input of the voltage regulator circuit and measured the output voltage coming out from the voltage regulator. For the regulator, we already knew that the input voltage we will supply to the regulator would have to be greater than the output voltage that we wanted to achieve (which was constant 12V). We can see in Fig 4.2.1 that the output voltage from the regulator remained constant (12.053V) as we slowly increased the input volt-age on DC power supply from 14V to 22.7V (the latter being the maximum amount of voltage allowed to be increased up to). But as we slowly began decreasing the input voltage below 13.85V, we can observe in Fig 4.2.2 that the output voltage, which we want it to be a constant 12.0V, starts to break out of constant voltage and stops regulating.

So we concluded from this experiment that we would need at least 13.55V input power source in order to maintain a constant 12.0 V that we want in order to charge a jumper battery.
Hyung Yoon, Da Zhao, and Yin Zhang were responsible for this task.

For this next experiment, we conducted our experiment outside on the sun and measured the voltage and current output reading from the solar panel with our portable digital multimeter. From the conclusion we have made in our previous experiment, we learned that we would need the output of the solar cells to be at least 13.55V in order to regulate it down to 12.0 V, which is how much we need to supply to our jumper battery. When we started this project, we took it into consideration that, in order to make the project more efficient and useful, the battery should charge not only under strong sunlight exposure, but also under minimal sunlight exposure on cloudy days. So as long as it is during the daytime and not raining or the weather condition is extremely heavy with clouds or too cold for the solar cells to receive any warm sunlight, we want our project to work. So we decided to test the output of solar cells on a cold and overcast day. The time of this experiment was 12:30 pm but many dark clouds were restricting the amount of sunlight going into our solar panel. Surprisingly, however, as we can see in Fig 4.2.3, we were able to obtain 14.51V reading from the solar panel under these weather conditions, which is a lot higher than the minimum amount of input voltage we need to the regulator circuit. In Fig 4.2.4, we show that the input voltage of 14.51V to the voltage regulator circuit outputted 12.02V, which is what we had expected.

From this experiment, we were able to prove that we could output 12.0V regulated voltage with the solar cells even on overcast days with minimal amount of sunlight exposure. Hyung Yoon, Da Zhao, and Yin Zhang were responsible for this task. Next, we will again test the output of solar cells, but on a sunny day with a strong sunlight.

In this next experiment, we took the test outside to the same place at the same time around noon the next day. The weather was 76 ?. As we can see in Fig 4.2.5, there was a clear sky and no clouds. So our solar panel was able to receive direct sunlight without any clouds on the way. We illustrate in Fig 4.2.6 that the voltage reading we obtained from the sunlight was meas-ured at 17.33V, which was higher than 14.51V measured on a cloudy day. Compared to Fig 4.2.3, we can clearly see that we are receiving full, direct sunlight here. Again we connected the output from the solar panel into our regulator circuit, and not surprisingly, we were able to regu-late it to 12.02V as we can see in Fig 4.2.7.

The voltage obtained in the above image was recorded at 17.33V, but from our numerous test-ing with solar panel, the highest voltage reading we had obtained previously was 20.80V on a hot day. How hot the weather is and how strong the sunlight is on a specific day has a big im-pact on the amount of voltage, as well as the current, the solar cells can output. But as men-tioned before, as long as the input voltage is above 13.55V from the sun, we can regulate that voltage to 12.0V. Hyung Yoon, Da Zhao, and Yin Zhang were responsible for this task.

Next, we are all good to go and about to charge a battery using solar cells. The car jumper bat-tery that we will experiment with has 12V DC and 300mA input. First of all, we had to completely drain the battery so that we would be able to fully charge it. We did this by connecting this bat-tery to a small motor fan and left it on for some time. This battery already came with a battery life indicator (Low, Med, and High) and we are able to see how the battery life is on it by press-ing the red button as demonstrated in Fig 4.2.8. It is hard to capture it in this image, but the red light is actually turned on at Low, as the red button that checks the battery life is pushed. Our goal is to charge this battery until we are able to see green light go on at Med and afterwards at High and measure the amount of time it takes. So we carried this experiment outside and set up the solar panel and breadboard next to each other like we have done in our previous experiment. The output from our breadboard (the voltage regulator and LED battery life indicator) will now be hooked up to the battery as you can see in Fig 4.2.9. We did not notice at the moment, but look-ing at the image here, a shade from the nearby lamp going through the solar panel is visible and it is hindering the amount of voltage going into our solar panel. The voltage we measured from solar cells was 16.0V, which we thought should have been higher. We now see that this was because the shade was blocking the amount of sunlight the solar cell was able to absorb. How-ever, this did not alter our result because the amount of output voltage was still being regulated to 12.0V.

The amount of current we measured ranged from 250mA to 400mA, so using the equation P = VI, we calculate the range to 12V x 0.25A and 12V x 0.4A, which are from 3W to 4.8W. This is the amount of power that will be supplied to the battery to charge it. Nicholas Kuhn, Steine Herman, Yong Kim were responsible for this task.