sciencehabit shares a report from Science Magazine: Like humans, solar panels don’t work well when overheated. Now, researchers have found a way to make them “sweat” — allowing them to cool themselves and increase their power output. In recent years, researchers have devised materials that can suck water vapor from the air and condense it into liquid water for drinking. Among the best is a gel that strongly absorbs water vapor at night, when the air is cool and humidity is high. The gel — a mix of carbon nanotubes in polymers with a water-attracting calcium chloride salt — causes the vapor to condense into droplets that the gel holds. When heat rises during the day, the gel releases water vapor. If covered by a clear plastic, the released vapor is trapped, condenses back into liquid water, and flows into a storage container.
Peng Wang, an environmental engineer at Hong Kong Polytechnic University, and his colleagues thought of another use for the condensed water: coolant for solar panels. So, the researchers pressed a 1-centimeter-thick sheet of the gel against the underside of a standard silicon solar panel. Their idea was that during the day, the gel would pull heat from the solar panel to evaporate water it had pulled out of the air the previous night, releasing the vapor through the bottom of the gel. The evaporating water would cool the solar panel as sweat evaporating from the skin cools us down. The researchers found that the amount of gel they needed depended primarily on the environment’s humidity. In a desert environment with 35% humidity, a 1-square-meter solar panel required 1 kilogram of gel to cool it, whereas a muggy area with 80% humidity required only 0.3 kilograms of gel per square meter of panel. The upshot in either case: The temperature of the water-cooled solar panel dropped by as much as 10C. And the electricity output of the cooled panels increased by an average of 15% and up to 19% in one outdoor test, where the wind likely enhanced the cooling effect, Wang and his colleagues report today in Nature Sustainability.
Read more of this story at Slashdot.