[BNC-grads-list] Fwd: [Reminder] Final Exam Announcement - Nov. 21, 3 PM, BRK 1001

[John Wilcox]

Scheduling of Examinations:
Student’s Name: John Wilcox
Examination Date: 11-21-2013
Examination Time: 3:00 PM
Building & Room: BRK 1001

Thesis Title: Solar Cell Temperature Dependent Efficiency and Very High
Temperature
Efficiency Limits

Abstract: Clean renewable solar energy is and will continue to be an
important source of electrical energy. Solar energy has the potential of
meeting all of the world’s energy needs, and has seen substantial growth in
recent years. Solar cells can convert sun light directly into electrical
energy, and much progress has been made in making them less expensive and
more efficient. Solar cells are often characterized and modeled at 25 °C,
which is significantly lower than their peak operating temperature. In some
thermal concentrating systems, solar cells operate above 300 °C. Since
increasing the temperature drastically affects the terminal
characteristics, it is important to quantify the losses caused by raising
the temperature. Methodologies for including the temperature dependent
material parameters in analytical and detailed numerical models have be
examined. The analytical model has been developed to analyze
Shockley-Queisser detailed balance limit, as well as the Auger, Radiative
and SHR recombination limiting cases from 25 °C to 800 °C, at 1x, 500x and
2000x suns concentrations. The results of this analysis show that the
efficiency of a direct bandgap material with an optimal bandgap could reach
19 % at 400 °C and 2000x suns, if the SHR recombination is reduced to an
acceptable level. An analytical solar cell model was also used in a
quasi-3D numerical model to simulate the temperature dependent resistivity
losses. It was found that the resistive losses can double when the
temperature of a solar cell increases from 25 °C to 100 °C. This will cause
the conversion efficiency temperature coefficient to deteriorate by 10%. By
using the temperature dependent material parameters for Si in a detailed
numerical model, it was found that some of the adjustable parameters,
increase the conversion efficiency temperature coefficient and the Voc,
while other parameters would only increase the Voc. This conclusion can be
used by solar cell manufactures to improve the solar cell parameters with
the biggest possible gain.



-- 
John Wilcox
jrwilcox at purdue.edu
Purdue University
School of Electrical and Computer Engineering
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