1. Solar Powered Power Bank
Yunjun Ling1, Emma Patterson2, Paige Williford3
1 Farragut High School 2 L&N Stem Academy 3 University of Tennessee, Knoxville
INTRODUCTION
Background:
We have an abundant amount of solar energy on this planet and we want to utilize it to benefit ourselves. In this project, we designed a solar powered buck converter to charge our power bank. The solar panels have a maximum output of 10 volts and 1 amp. In this case, our buck converter will be able to convert the higher voltage from the solar panels to a constant 5 volts output.
Objective:
Use solar panels to capture the sun’s rays as a renewable energy source
Build a buck converter to supply the battery bank the appropriate amount of voltage from the solar panels
BUCK CONVERTER DESIGN
Overview:
Each solar panel could supply 5V and ½ A. Tests were conducted using four solar panels. Two were connected by series, which brought the total input voltage to 10V, and two series of solar panels were connected by parallel to bring the total current to 1A.
Components of the Buck Converter
Testing Setup Outside
RESULTS
Efficiency Equation:
η= Vout(Iout)/Vin(Iin)・100%
Efficiency Calculation:
η= 4.99V(0.885A)/10V(0.58A)・100%
Results:
Inside: 76%
Outside: 72%
Ideal Output vs. Tested Output.
Solid lines represent the ideal output. Dotted lines represent the tested output.
Input and output waveforms.
The test results from oscilloscope showing that as the MOSFET turns on, the inductor current increases, and as MOSFET closes, the current drops.
CONCLUSION
Conclusion:
Designed a solar buck converter to step down the voltage to maintain 5V
The Buck Converter produced a lower output than ideal due to losses occurring throughout the circuit
The Buck Converter had an efficiency around 70% inside and outside with the battery bank as our load
Future Goals:
Replace diode with another MOSFET
Replace the current MOSFET with a more suitable one
Replace Arduino board with a microprocessor
More powerful solar panels
More efficient board