ABSTRACT
Radiative cooling presents a method for reducing the operational temperature of solar panels without additional energy consumption. However, its applicability to PV modules has been limited by the thermal properties of existing materials. To overcome these challenges, we introduce a V-shaped design that enhances cooling in vertical PV modules by effectively harnessing thermal radiation from both the front and rear sides, resulting in a substantial temperature reduction of 10.6°C under 1 sun illumination in controlled laboratory conditions. Field tests conducted in warm and humid conditions, specifically in Thuwal, Saudi Arabia, demonstrate a remarkable 15% increase in efficiency while maintaining an operating temperature 0.2°C lower than that of conventional horizontal PV modules, corresponding to a significant 16.8% increase in power output. Our innovative V-shaped design offers a promising thermal strategy suitable for diverse climates, contributing to improved performance and reduced module temperatures, thereby supporting the global pursuit of carbon neutrality.
ABSTRACT
Heat stress is being exacerbated by global warming, jeopardizing human and social sustainability. As a result, reliable and energy-efficient cooling methods are highly sought-after. Here, we report a polyacrylate film fabricated by self-moisture-absorbing hygroscopic hydrogel for efficient hybrid passive cooling. Using one of the lowest-cost industrial materials (e.g., sodium polyacrylate), we demonstrate radiative cooling by reducing solar heating with high solar reflectance (0.93) while maximizing thermal emission with high mid-infrared emittance (0.99). Importantly, the manufacturing process utilizes only atmospheric moisture and requires no additional chemicals or energy consumption, making it a completely green process. Under sunlight illumination of 800 W m-2, the surface temperature of the film was reduced by 5 °C under a partly cloudy sky observed at Buffalo, NY. Combined with its hygroscopic feature, this film can simultaneously introduce evaporative cooling that is independent of access to the clear sky. The hybrid passive cooling approach is projected to decrease global carbon emissions by 118.4 billion kg/year compared to current air-conditioning facilities powered by electricity. Given its low-cost raw materials and excellent molding feature, the film can be manufactured through simple and cost-effective roll-to-roll processes, making it suitable for future building construction and personal thermal management needs.
ABSTRACT
Direct solar desalination exhibits considerable potential for alleviating the global freshwater crisis. However, the prevention of salt accumulation while maintaining high water production remains an important challenge that limits its practical applications because the methods currently employed for achieving rapid salt backflow usually result in considerable heat loss. Herein, we fabricate a solar evaporator featuring vertically aligned mass transfer bridges for water transport and salt backflow. The 3D open architecture constructed using mass transfer bridges enables the evaporator to efficiently utilize the conductive heat that would otherwise be lost, significantly improving the water evaporation efficiency without compromising on salt rejection. The fabricated evaporator can treat salt water with more than 10% salinity. Moreover, it can continuously and steadily work in a real environment under natural sunlight with a practical solar-to-water collection efficiency of >40%. Using the discharged water from reverse osmosis plants and sea water from the Red Sea, the evaporator demonstrates a daily freshwater generation rate of ~5 L/m2, which is sufficient to satisfy individual drinking water requirements. With strong salt rejection, high energy efficiency, and simple scalability, the 3D evaporator has considerable promise for freshwater supply for water-stressed and off-grid communities.
ABSTRACT
A ZnO/Ag/ZnO film with 2D periodic apertures can have a high visible transmittance and low emittances in atmospheric windows for visible-infrared compatible camouflage and a high transmittance in 5-8 µm for heat dissipation by radiation. This following protocol details the fabrication process of such a photonic structure based on photolithography technology. Also described are the related challenges and troubleshooting steps. For complete details on the use and execution of this protocol, please refer to Dang and Ye (2021).
