How solar thermophotovoltaics are paving the way for a renewable future

Solar energy is the most abundant energy source on Earth. Although solar photovoltaics (PV) play a leading role in the development of renewable energy technologies, direct use of solar energy is limited by low energy conversion efficiency.

While solar thermophotovoltaics are considered one of the best routes to achieving high energy conversion efficiency, there are a variety of optical or thermal losses resulting in an efficiency currently reported at less than 10%.

The sources of limitations and energy conversion losses are identified through a review of previous experiments. In this study, the authors analyzed key components of the system, structural designs and ways to reduce cost.

Wang et al. believe efficiency can be improved by increasing the operating temperature and enhancing the radiation transfer efficacy between components. By accomplishing this and achieving fine spectrum control, they indicate, in principle, a 70% efficiency can be achieved.

“High efficiency is desirable for numerous applications, particularly in missions to outer space. The first priority is to exceed the efficiency in commonly-used solar cells, such as silicon and GaAs (gallium arsenide) solar cells,” Zhu said.

The authors examined ways in which energy conversion efficiency could be accomplished through each step of the process of solar energy conversion. They reviewed research on a wide variety of absorbers (such as selective, blackbody and absorbers currently in use), emitters (such as edge emitters and narrowband emitters) and PV cells.

They also compared absorber-to-emitter loss and emitter-to-cell loss, providing an in-depth perspective on opportunities for solar thermophotovoltaics.

Source: “Solar thermophotovoltaics: Progress, challenges and opportunities,” by Yang Wang, Haizhou Liu, and Jia Zhu, APL Materials (2019). The article can be accessed at https://doi.org/10.1063/1.5114829 .