Cooling solar panels with water isn’t an entirely new concept. Researchers discovered this method decades ago. Nowadays, some companies even sell water-cooled systems. However, those systems require a large amount of available water and storage tanks, pipes, and pumps. That’s not sustainable in dry regions or developing countries with a lack of infrastructure.
This is where an atmospheric water collector comes into play. Researchers have recently created materials that can suck water vapours from the air and condense it into liquid water for drinking. One of the best materials researchers have come up with is a gel that absorbs water vapour at night when it’s cool and humid. The gel causes the moisture to condense into droplets that it stores and subsequently releases the water vapour when the heat rises during the day. If covered by plastic, the released vapour is trapped and subsequently condensed back into liquid water. From there, it flows into a storage container.
Engineers at Hong Kong Polytechnic University realized that condensed water could be used as a coolant for solar panels. The engineers’ idea was to press the gel against the underside of a standard silicon solar panel. They hypothesized 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 vapour through the bottom of the gel. The evaporating water would subsequently cool down the solar panel.
The researchers tested this method in two different environments – a dry, desert environment and a humid environment – tailoring the amount of gel used to the environment’s humidity. In both cases, the outcome was that the temperature of the water-cooled solar panel dropped by as much as 10 degrees Celsius. The electricity output of the water-cooled panels also increased by an average of 15%. One outdoor test even showed the electricity output of the panels increased by 19%. In this case, the wind probably assisted with the cooling of the panels.
The researchers also discovered that rain could dissolve the calcium chloride salt in the gel affecting the gel’s water-attracting performance. However, if the gel is placed underneath the solar panel, it’s shielded from the rain in most instances. The researchers are also working on a second-generation gel that wouldn’t be affected by the rain.
Another design option is a system that would be able to trap and recondense water after it evaporates from the gel. That water could be utilized to clean any dust buildup on the panels. This would resolve another power-draining problem that commonly affects solar panels. Additionally, that water could be stored for drinking, which could solve many issues in dry climates and in developing countries where clean drinking water is an issue.
