Some science with solar panels

   Currently I believe that one of the most popular green energy method that exists are the solar cells (photovoltaic cells) . With this being said , I believe is its quite appropriate that last weeks lab experiment we worked with a solar cell cell. For this experiment we used a flashlight as our light source, a solar cell that was connected to the Lego Mindstorm which will also work as a voltmeter and measure the output voltage  that results from the light received by the solar cell.We wanted to test two things:

1. The relationship between the distance from the light source to the solar cell ans the resulting output voltage.

2. The relationship  of the light absorbance of colors.

   For both experiments we obtained a table of results and its graphical representation(this will the analysis of the results  easier)

   For the first experiment we started measuring the voltage when there is no light; this value was our reference value ( Vo=0.0353 volts). Our results should be higher than  the reference value since  for  our actual experiment we will be applying direct light to the solar cell. We started our measurements at an initial position of x= 0 inches or 0 centimeters(cm). We pointed out flashlight directly at the solar cell and measured the output voltage; then we incremented the distance o between the source(flashlight) and the receiver ( solar cell) and repeated the procedure. We  incremented  the distance every time by 3 inches, but our results were recorded in centimeters since this is the proper unit for the metric system. These are our results for  our first experiment.

  Table1 : Output voltage from the solar cell  with respect to the distance between source and receiver

Graph 1: Graphical representation of the results shown in Table 

   As you can see there is one  particular value that doesn’t quite  follow the  trend line; the value at  x=7.62 cm is too low  than the expected value. The reason for this numbers s that the light was not directly pointing to  the solar cell but it was only pointing to  one section of the panel. After realizing our mistake, we were more careful for the next runs and always pointed the light to the center of the  solar cell.

   For our second experiment we did something a little bit more different. We placed  difference color  sheets between the solar cell and the flashlight.   As you may already know the reason is that can see colors is because when light  hits an object; all the colors are absorbed  by the object except one that gets reflected  which is the  color that we see; you can see a representation of this below:

Image1 : Color reflection

   Since colors get absorbed, that leads us to think that placing  a color sheet in between our light source and the receiver will  result in a change of the amount of light that  gets to the solar cell and  therefore the output voltage  generated by the solar cell.   We tested different colors: green, red, yellow and blue.  We are expecting to have  the least amount of output voltage  after using the darkest color( blue) and  the highest amount of the  voltage  from the lightest color red . Here are our results:

Table 2: Output voltage  for each color filter

Graph 2: Graphical representation of the light absorbance

  From Graph 2 you can see that our values were are expected the amount of  voltage that we generated  while  the blue  filter was applied was significantly  less than the amount of voltage that was generated when the red filter was used.

   From this experiment I learned the importance of the angle that the solar cells are placed on the panel; since the output voltage that will be  obtained from these won’t be as high as it could potentially be. I also learned that  we won’t be able to produce as much voltages if we filtered the light with dark color materials.