Researchers have developed a still water layer cooling concept and tested it with seawater, tap water and desalinated water. The panel temperature dropped by up to 8.2°C, while the power increased by approximately 28%.
An international research team has proposed a new stagnant water layer cooling technology for solar panels.
“This work introduces a simple, cheap and innovative method for the immersion cooling of PV modules, so that the junction box and aluminum frame remain isolated from liquid contact,” the researchers explained.
To evaluate the system’s performance, the team built an experimental setup and tested the cooling technology with three types of water: seawater, tap water and desalinated water. “We compared the performance of the reference (uncooled) PV module with that of the water-immersion cooled PV module in terms of energy output, electrical efficiency, exergy efficiency and sustainability index,” they added.
Both the reference and cooled water immersion systems were based on a 1 kW solar module. For the cooled panel, four transparent glass strips, each 3.0 mm thick and 30.0 mm high, were attached along the perimeter of the front surface of the PV module using silicone adhesive. This configuration created an open water container with a 1.0 cm thick layer of water.
The experiments were conducted between 9:30 AM and 4:30 PM in May and June 2024 at the Indian Institute of Petroleum and Energy (Iipe) in Visakhapatnam, eastern India. The seawater used in the experiments had a pH of 7.96, an electrical conductivity of 50,456.67 μs/cm, total dissolved solids of 25,230 ppm, salinity of 32.92 psu, and turbidity of 0.71 nutu.
Tap water had corresponding values of 6.67, 1,160 μs/cm, 580 ppm, 0.57 psU and 0.36 NTU, while the desalinated water measured 6.26, 38.33 μs/cm, 19.33 ppm, 0.02 psU and 0.28 NTU, respectively.
The researchers reported that desalination water produced the greatest temperature reduction compared to the reference module – 8.2 C – resolving a 28.3% increase in daily energy output. Seawater reduced module temperature by 7.4°C and boosted output by 14.9%, while tap water achieved a temperature drop of 7.2°C and an increase in energy output by 16.6%.
“For each additional watt-hour of energy generated, approximately 97 ml of seawater, 106 ml of tap water and 68 ml of desalination water were consumed in cooling the PV module with the respective fluids,” the researchers noted. “Evaporation losses were highest for desalinated water and lowest for seawater. Interestingly, no salt deposition was observed during the experimental period, possibly for seawater, possibly due to the daily replacement of the water layer.”
The team further highlighted that “the seawater-based PV array achieved the lowest electricity generation cost and outperformed both tap-water and desalinated-water-based arrays in terms of module lifetime, due to the abundant availability and negligible cost of seawater.”
However, from the environmental perspective, the PV array showed the best performance in the field of desalinated water. Over a 20-year lifetime, the net emissions reduction potential was found to be 44.2% higher than that of the reference PV array.
The details of the cooling systems can be found in “Performance and water-energy nexus aspects of stagnant water layer cooled zero-tilt solar photovoltaic module” Published in Scientific reports. Researchers from the Indian Institute of Petroleum and Energy (IIPE), India’s Andhra University (AU), the center of Rajiv Gandhi Institute of Petroleum Technology (RGIPT) and Spain’s University of Jaen participated in the study.
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