Passive radiative cooling and other photonic approaches for the temperature control of photovoltaics: a comparative study for crystalline silicon-based architectures

Abstract

The radiative cooling of objects during daytime under direct sunlight has recently been shown to be significantly enhanced by utilizing nanophotonic coatings. Multilayer thin film stacks, 2D photonic crystals, etc. as coating structures improved the thermal emission rate of a device in the infrared atmospheric transparency window reducing considerably devices' temperature. Due to the increased heating in photovoltaic (PV) devices, that has significant adverse consequences on both their efficiency and life-time, and inspired by the recent advances in daytime radiative cooling, we developed a coupled thermal-electrical modeling to examine the physical mechanisms on how a radiative cooler affects the overall efficiency of commercial photovoltaic modules. Employing this modeling, which takes into account all the major processes affected by the temperature variation in a PV device, we evaluated the relative impact of the main radiative cooling approaches proposed so far on the PV efficiency, and we established required conditions for optimized radiative cooling. Moreover, we identified the validity regimes of the currently existing PV-cooling models which treat the PV coolers as simple thermal emitters. Finally, we assessed some realistic photonic coolers from the literature, compatible with photovoltaics, to implement the radiative cooling requirements, and demonstrated their associated impact on the temperature reduction and PV efficiency. Providing the physical mechanisms and requirements for cooling radiatively solar cells, our study provides guidelines for utilizing suitable photonic structures as radiative coolers, enhancing the efficiency and the lifetime of PV devices.

Flexible 3D Printed Conductive Metamaterial Units for Electromagnetic Applications in Microwaves

“…Metamaterials and their two dimensional analogues, metasurfaces, are artificial materials with purposefully designed subwavelength, periodic elementary units, the meta-atoms, which provide controllable interactions with electromagnetic (EM) waves and enable exotic electromagnetic functions [ 1 , 2 ]. Metamaterials and complex media have been extensively experimentally evaluated and tested for real life applications and devices, such as antennas, sensors, splitters, isolators, modulators, electromagnetic shieldings and energy harvesters, in a large frequency range [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Their properties depend on both the meta-atoms’ architecture, and the constituent materials, which can be dielectrics, metals, semiconductors or 2D materials [ 15 , 16 , 17 , 18 ].…”

Thermodynamic limits for simultaneous energy harvesting from the hot sun and cold outer space

“…For example, for solar energy harvesting systems, reducing the cell temperature by utilizing outer space will directly lead to improved efficiency 24,27,43 . There have been some efforts along this direction with single-junction solar cells 27,[45][46][47][48] . Our analysis here indicates that the beneficial effect of radiative cooling is much more significant for multijunction cells, solar thermophotovoltaics and the Landsberg setup.…”

“…Recently, a tandem system that spectrally separates solar absorption and outgoing thermal radiation into a top infrared transparent solar absorber and a bottom radiative cooler was demonstrated for simultaneous solar heating and radiative cooling 42 . There have also been efforts aiming to improve solar cell performance through radiative cooling 27,[43][44][45][46][47][48] . However, for energy harvesting purposes, the full potential and the fundamental limits of systems that can simultaneously utilize the sun and outer space have not been elucidated.…”

THERMAL MANAGEMENT OF SILICON PHOTOVOLTAIC PANELS: A REVIEW (In the press)

“…24. Comparison of calculated and tested emissivity, [41] Radiative cooling approaches for the thermal regulation of silicon PV panels were presented and discussed in study [42]. A modelling approach was applied in order to analyze mechanisms and requirements for an efficient radiative cooling.…”