Photovoltaic Analysis of a Solar Tracker Daniel Conway Department of Electrical and Computer Engineering, Iowa State University, IA - 50011 Background Methods Further Work Conclusions Results Acknowledgements Introduction CONTACT REPLACE THIS BOX WITH YOUR ORGANIZATION’S HIGH RESOLUTION LOGO Daniel Conway Email: [email protected] Ankeny Centennial High School Photovoltaics is the conversion of light into electricity using semi- conductive materials. This term is most commonly known to be attached to solar panels. Most individuals have heard of the concept of these solar cells, but most to not know that there are different types and methods of collecting light. The data on this poster deals with two different encapsulations as well as methods of collecting photons. The goal of the research conducted is to analyze the difference in output of a stationary solar cell and one on a tracker to determine the best and most efficient way of utilizing solar cells. As shown in figure 1 below, the decay of the lensed stationary cell is much higher than the flat cell on the tracker. The efficiency of the solar tracker proved to be superior, never going below 85% efficiency during the course of a day. A small dip is expected for two main reasons. One, the tracker was only single axis: not receiving full range of motion to be perfectly perpendicular to the sun. Second, the solar flux naturally decreases as it moves away from solar noon and vice versa as rays will start to be blocked from reaching the surface as the sun moves away from solar noon, decreasing solar flux. The lensed cell, even with assistance from the lensing reached 33% and was continuing to crash. With the sun rising and setting, the cell, while creating more power at its peak, decreases output heavily as the sun moves away from solar noon, creating less photons hitting the solar cell as well as changing the angle of entry to a non-perpendicular angle, decreasing efficiency. The data shows for the tracker to be more efficient at creating power in the same conditions as a cell that is flat down on a surface, even with the aid of lensing. The incredibly superior efficiency of the sun tracker from the data collected leads to the observer to conclude that solar tracking is a better way of increasing the output of a solar cell compared to lensing. Although a test of a stationary flat panel was not conducted, it would not make sense for that trial to produce data that shows greater efficiency than even the lensed panel. A continuation of the stationary lensed panel would show greater declination of current while the flat tracker panel continues steadily. After normalization, the minimum efficiency of the tracker is over 50% greater than the flat lensed panel. The conclusion of superior efficiency from the data collected can be easily determined as the tracker is far more superior. This conclusion can be used when analyzing how a consumer would best create the greatest efficiency of a solar cell or panel in the local area as data will change with location. The steps to achieve results include: •Gain a basic understanding of photovoltaics •Program the stepper motor using Python to rotate the solar panel so that it is perpendicular to the sun throughout the day •Construct a frame to hold the hardware and to protect it from environmental factors such as high winds and rain fall •Use a wireless multimeter to log current of the solar cell for each trial •Convert the text file into a spreadsheet using Microsoft Excel Future work mainly includes further testing. Only one trial was able to be gathered in the allowed amount of time. Further trials would create a more accurate conclusion when averaging data. A control trial of a stationary flat solar panel would be useful in gaining more information on the benefits of applying a single axis tracker. Finally, sophisticated hardware would increase data logging times and reduce interruption. Photovoltaic cells, or solar cells, convert light into electricity. While the analysis of the output of a tracking solar panel has been performed, none have been conducted in this area. Because of this, testing in the local area will create more accurate results to use as reference in future related experiments. The “Flat” photovoltaic (solar) cell refers to a solar cell that is encapsulated with a flat plastic A “Lensed” cell contains concentrator cells which use a plastic Fresnel lens to focus sunrays onto the surface of the cell, increasing power output. Thanks is given to the Young Engineers and Scientists program and Iowa State for making this opportunity possible and allowing access to the campus and its resources. I would also like to thank Vikram Dalal and Istiaque Hossain for providing guidance and funding along the process as well as Liang Zhang for programming assistance and Max Noack for hardware support. The entire solar tracker unit Figure 1: Graphed current throughout half of a day Lensed Solar Panel Flat Solar Panel Microcontroller and Raspberry bi used to control The material presented here is based upon work supported by the Nation Science Foundation under Award No. EEC-0813570. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.