Investigating the Effect of Radiative Cooling on the Operating Temperature of Photovoltaic Modules

Abstract

Due to the linear decrease in power conversion efficiency with temperature, effective methods for the thermal management of silicon photovoltaics (PV) are urgently needed. Recently, the emergence of radiative cooling technologies has breathed new life into this topic. Some previous studies claimed the value of an additional radiative cooling coating on silicon solar cells, whereas quantitative analysis based on comprehensive experiments and modeling is still not available in literature to give an explicit conclusion. After developing the coupling electrical–thermal model for simulating various cases and conducting field experimental tests, herein, it is aimed to clarify the effect of radiative cooling on the temperature of normally installed PV modules and influence of factors such as thermal convection and thermal emissivity. Results show that the increased thermal emissivity results in only an average temperature drop of less than 1.0 °C, whereas the ventilation conditions have an impact of over 10 °C. The simulation study also demonstrates that a limit of around 2.0 °C in temperature reduction is all the value of an additional radiative cooling coating on PV modules. To make an additional radiative cooling coating on existing PV panels cost effective, the work suggests developing multifunctional coatings in the future.

Tunable Photovoltaics: Adapting Solar Cell Technologies to Versatile Applications

“…[169,[181][182][183] The above mentioned optical tuning strategies like subbandgap reflection methods and passive radiative cooling concepts are beneficial for the appropriate thermal management of PV devices. [184][185][186][187]…”

“…The emergence of PRC concepts has stimulated numerous reports to present overview about the integration of this technology in PV. [177,181,185,405,406] It is important to mention that different antireflection coatings on bare silicon SCs, and, in particular, glass covers with large amount of silica in standard solar panels already possess a considerable emissivity level. [86,185,187,407] However, highly efficient IR emitter alternatives are desired, not only to further boost the radiative cooling performance, but also to be adaptable with flexible, lightweight PV technologies, and in concentrated PV and extraterrestrial environments such as space.…”

“…[177,181,185,405,406] It is important to mention that different antireflection coatings on bare silicon SCs, and, in particular, glass covers with large amount of silica in standard solar panels already possess a considerable emissivity level. [86,185,187,407] However, highly efficient IR emitter alternatives are desired, not only to further boost the radiative cooling performance, but also to be adaptable with flexible, lightweight PV technologies, and in concentrated PV and extraterrestrial environments such as space. To fulfill this aim, various IR emitter structures can be employed such as nanophotonic structure, metamaterials, and polymer layers.…”

“…[404] The ultimate capacity of passive radiative cooling is still rising debates in the scientific community, especially for conventionally installed PV panels. [184,185,187] On the one hand, substantial temperature reductions above 10 °C were either predicted or achieved in comparison with surfaces having very low thermal emissivity like bare silicon wafer. On the other hand, the impact of radiative cooling in temperature reduction became less apparent when considering comparisons with coated SCs or glass cover having much higher thermal emissivity.…”

“…Moreover, very little cooling gain below 2 °C is reached only even with using IR emitters with high emissivity. [185,187] Thus, careful considerations should be taken in the estimation of radiative cooling potential including the specifications of the PV technology and the operation conditions. [185]…”