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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
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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.