Is a Sun-Solar Cell System Truly Equivalent to a Carnot Engine?

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SUMMARY

The discussion centers on the analogy between a sun-solar cell system and a Carnot Engine, as presented in a semiconductor course. The professor's assumption of the sun's surface temperature at 6000K and the solar cell's temperature at 300K leads to an idealized efficiency calculation of nearly 100% using the formula (1-T1/T2). However, participants argue that this analogy is misleading due to the actual efficiency of solar cells being limited by factors such as band gap energy and black body radiation, which yield realistic efficiencies between 16-32%. The consensus is that while the Carnot analogy has some theoretical merit, it distracts from the practical understanding of solar cell performance.

PREREQUISITES
  • Understanding of Carnot efficiency and thermodynamics
  • Knowledge of semiconductor physics and solar cell technology
  • Familiarity with black body radiation concepts
  • Basic proficiency in efficiency calculations and thermodynamic equations
NEXT STEPS
  • Research the principles of black body radiation and its impact on solar cell efficiency
  • Study the relationship between band gap energy and photon energy in solar cells
  • Explore the limitations of solar cell technology in achieving Carnot efficiency
  • Investigate real-world efficiency metrics for various solar cell types
USEFUL FOR

Students in semiconductor courses, solar energy researchers, engineers working on solar technology, and anyone interested in the theoretical and practical aspects of solar cell efficiency.

jontyjashan
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I have undertaken a course on Semiconductors. My professor told us that a sun-solar cell system can be taken as a Carnot Engine. He assumed that the surface temperature of sun is 6000k and that of solar cell is 300k.And then he found out the efficiency by (1-T1/T2), which came out close to be around 100 percent. How far this analogy is true? And on the first note, why is this analogy made? Can I get some serious calculations?
 
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I think it is a major distraction.
The wavelength of the light from the sun is narrow band because it passes through the atmosphere.
The efficiency of a solar cell involves it's band gap energy matching the energy of the available wavelength photons.
 
Agreed. Seems a very odd/pointless calculation. Clearly, right now solar cells are limited by other issues that keep them well below Carnot efficiency.
 
Hmmm. Sounds to me like someone trying to be too damned smart by saying something just to confuse the students. There may be some validity there but he certainly isn't help anyone's understanding of anything.
 
He also said that if we take into account black body radiations , then we can make calculations very close to the actual efficiency(around 16-32 percent).
 
jontyjashan said:
He also said that if we take into account black body radiations , then we can make calculations very close to the actual efficiency(around 16-32 percent).
That part is true and much better than using Carnot.
 
OK. Can I get a link or the actual calculations themselves?
 
http://org.ntnu.no/solarcells/pages/Chap.2.php
 
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