It is widely known that the conversion efficiency and lifetime of solar cell modules decrease with higher operating temperatures. To maximize both efficiency and reliability, solar cell modules benefit greatly from the use of daytime passive radiative cooling techniques. In this study, we introduce a simple, low-cost, double-layer coating based on porous T i O 2 as a daytime passive radiative cooling system to achieve sub-ambient operating temperatures in a solar cell module. The top and bottom layers of the implemented design are porous T i O 2 and BK7 (glass), respectively. This solar cell/radiative cooling hybrid design is capable of achieving both high solar absorption in the photovoltaic conversion band 0.3–1.1 µm and high emissivity over 0.96 in the atmospheric transparency window 8–13 µm, while rejecting parasitic solar absorption. At 800 W / m 2 solar heating power, we found that adding the proposed cooling design on top of mono-crystalline silicon (m-Si), the solar cell panel lowered its operating temperature by 18.04°C, leading to a relative (effective) efficiency advantage of 21.56%. Additionally, at steady-state temperature (325 K), the power conversion efficiency of our radiative-cooler-coated m-Si solar cell is estimated to reach 20.46%, in contrast to 16.83% for an uncoated silicon solar cell. When compared with an uncoated silicon solar cell, optoelectronic simulations of our coated silicon solar cell show a short-circuit current density J s c as high as 5.07 m A / c m 2 , and the open circuit voltage V o c increased from 771.78 to 776.3 mV.

Passive daytime radiative cooling remains a topic of intense interest that has gained great attention recently, mainly due to its important applications, such as electronic heat dissipation, solar cells, and photo-thermal technologies. In order to achieve the daytime radiative cooling for thermal management applications, a new smart shield should be designed to have both a low absorptivity in the solar range of 0.3–2.5 µm and high emissivity in the atmospheric transparency windows of 8–13 µm and 16–26 µm. In this work, we propose and analyze a new, inexpensive, and highly scalable double-layer coating to reach an efficient passive daytime radiative cooling. Double-layer coatings consisting of a top T i O 2 porous adsorbent layer and a bottom providing excellent transmittance in the solar spectrum are achieved properly by borosilicate-crown glass (BK7). We have shown that the proposed device preserves an average absorptivity/emissivity well below 7% in the entire solar spectrum and almost 95% in the atmospheric transparency windows. Besides, our design allows for sub-ambient temperature drops of 45° and diurnal cooling power output of 133 W / m 2 , even in the case of solar irradiance up to 1000 W / m 2 . The cooling performance persists under high humidity, even when taking the non-radiative heat exchange progress into account. The results revealed that the proposed design can be easily applied to a large area and promotes a significant step towards achieving large scale application in solar cells and related systems.