Thermodynamic efficiency of solar concentrators.

Area of Science:

• Thermodynamics
• Geometrical Optics
• Solar Energy Engineering

Background:

• Evaluating nonimaging concentrators requires a comprehensive metric accounting for all optical losses.
• Existing methods may not fully capture the thermodynamic limitations of flux transfer.

Purpose of the Study:

• To develop and present a novel metric, optical thermodynamic efficiency, for assessing nonimaging concentrators.
• To integrate the first and second laws of thermodynamics into a unified performance evaluation.

Main Methods:

• Discussing consequences of Fermat's principle in geometrical optics.
• Reviewing étendue dilution and optical loss mechanisms in nonimaging systems.
• Deriving an expression for optical thermodynamic efficiency.

Main Results:

• The optical thermodynamic efficiency metric comprehensively accounts for all flux transfer loss mechanisms.
• This metric serves as a gold standard for evaluating nonimaging concentrator performance.
• Skewness mismatch is identified as a limiting factor for attainable optical thermodynamic efficiency in concentrating photovoltaic systems.

Conclusions:

• Optical thermodynamic efficiency provides a robust framework for performance evaluation of nonimaging concentrators.
• The metric is particularly valuable for optimizing concentrating photovoltaic systems for solar power.
• Understanding and mitigating skewness mismatch is crucial for maximizing solar energy conversion efficiency.