As the scorching summer heat burns away the last traces of spring, words like air conditioning and vacation spots to beat the heat have once again topped the most searched keywords list. But humans aren’t the only ones that need to escape the heat. Excess heat can hamper the performance of solar panels, making them less effective at generating electricity. In light of this, a group of researchers from Egypt have recently come up with a water cooling system for solar panels.
Solar panels are now enjoying increasing popularity in various regions thanks to constant improvements in technology and cost. In particular, the EMEA solar market has been growing at breakneck speed in recent years. Thanks to advantages both natural and commercial, such as abundant sunlight and ample room for market growth, photovoltaic companies are charting new waters in the proverbial blue ocean that is EMEA.
As previously mentioned, the efficiency of solar panels depends not only on the availability of sunlight, but also on their environmental temperature. Heat (or, more specifically, overheating) remains one of the major bottlenecks in photovoltaics development. To address this pressing issue, researchers from Benha University in Egypt are currently looking into a solution that cools solar panels from the inside out using a mixture of water, Al2O3 (aluminum oxide), and CaCL2H12O6 (calcium chloride hexahydrate).
This project is quite similar to a type of cooling system developed by French photovoltaics company Sunbooster. Sunbooster’s system features a series of holed pipes mounted along the top edge of solar panels. When the ambient temperature exceeds 25 °C, the system flushes its solar panels with water from the pipe holes, which both cools and cleans the panels. The French company claims its system can allow solar panels to generate up to 8-12% more electricity per year once installed.
On the other hand, the cooling system developed by Benha researchers is mounted under the panels. “The system involved the use of cooling unit, DC pump, valves, water flow meter and connecting pipes”, according to Emiliano Bellini, writing for PV Magazine. “Aluminum channels were fabricated for the water and the Al2O3/PCM (phase change material) mixture.” This mixture is capable of exerting a cooling effect on the solar panels.
Calcium chloride is generally used as a dehumidifying agent, antifreeze, or ice melt. Calcium chloride hexahydrate, however, also doubles as a type of phase change material here. Due to its 30°C boiling point and 190 KJ/mol enthalpy of fusion (the energy required to reach a melting state), calcium chloride hexahydrate can be used to absorb low to medium latent excess heat from industrial processes as well as solar radiation.
The Benha researchers employed both experimental and control groups when testing their solar cooling system. In addition to environmental factors, such as sunlight, wind speed, and ambient temperature, they took extensive notes of differences in electrical current, voltage, and surface temperature pre- vs. post-coolant use. “Applying the cooling system, whether using water and/or [the] Al2O3/PCM mixture provides a noticeable drop in cell temperature compared with the uncooled [panel],” said the Egyptian team.
According to the tests, a mixture of water and Al2O3/PCM provides superior cooling performance compared to water alone, but the optimal ratio is 75% water with 25% Al2O3/PCM.