Solar Thermoradiative-Photovoltaic Energy Conversion

TL;DR

This paper introduces a solar thermoradiative-photovoltaic system that leverages radiative heat exchange to achieve high conversion efficiencies, outperforming traditional thermophotovoltaic devices, and can be paired with thermal storage for reliable power.

Contribution

It presents a detailed balance-based analysis of a novel solar energy conversion system combining thermoradiative and photovoltaic cells with high efficiency potential.

Findings

Limiting efficiency of 85% under concentrated sunlight.

Performance surpasses solar thermophotovoltaic systems at low bandgaps.

Potential efficiency increase of up to 7.9% compared to thermophotovoltaics.

Abstract

We propose a solar thermal energy conversion system consisting of a solar absorber, a thermoradiative cell or negative illumination photodiode, and a photovoltaic cell. Because it is a heat engine, this system can also be paired with thermal storage to provide reliable electricity generation. Heat from the solar absorber drives radiative recombination current in the thermoradiative cell, and its emitted light is absorbed by the photovoltaic cell to provide an additional photocurrent. Based on the principle of detailed balance, we calculate a limiting solar conversion efficiency of 85% for fully concentrated sunlight and 45% for one sun with an absorber and single-junction cells of equal areas. Ideal and nonideal solar thermoradiative-photovoltaic systems outperform solar thermophotovoltaic converters for low bandgaps and practical absorber temperatures. Their performance enhancement results from a high tolerance to nonradiative generation/recombination and an ability to minimize radiative heat losses. We show that a realistic device with all major losses could achieve increases in solar conversion efficiency by up to 7.9% (absolute) compared to a solar thermophotovoltaic device under low optical concentration. Our results indicate that these converters could serve as efficient heat engines for low cost single axis tracking systems.