Solar cells and thermoelectric generators as finite-time chemical heat engines

TL;DR

This paper explores the thermodynamic similarities between solar cells and thermoelectric generators, analyzing their efficiency limits and the impact of finite-time thermodynamics on their performance.

Contribution

It introduces a unified thermodynamic framework for both energy converters, highlighting the intrinsic efficiency limitations and the effects of finite-time processes.

Findings

Maximum efficiency is lower than Carnot efficiency due to Seebeck coefficient variations.

Finite-time thermodynamics models reveal additional performance losses.

Potential strategies may recover some efficiency losses.

Abstract

This paper shows a fundamental thermodynamic similarity between thermoelectric and photovoltaic energy converters which, at open circuit, can be represented as isochoric engines generating a finite chemical potential which appears as voltage at the terminals of the device. We show that, allowing for the temperature variation of the Seebeck coefficient, the maximum energy efficiency is intrinsically lower than the Carnot efficiency, as assumed in most of the literature, although more sophisticated strategies may exist to recuperate this loss. At finite current, further losses can be modelled in terms of finite-time thermodynamics.