Scientists from the United Arab Emirates (UAE) have developed a new technique for cooling double-sided photovoltaic modules based on a mist cooler placed between both sides of the panel.
They tested it in the extremely hot climate of the UAE and achieved significant results. ‘The novelty of our research lies in the development of a new type of solar panel called a sandwich bifacial photovoltaic panel (sbPV),’ said author Zafar Said.
‘Unlike traditional solar panels, which suffer from efficiency losses in extremely hot conditions, our mist-cooled design maintains a lower temperature, which significantly increases efficiency and energy production.’
To create the sbPV, the team took two 60 W monocrystalline panels and installed them back-to-back. A mist cooling system was modified to suit the installation: 16 mist nozzles were installed behind the front panel and 16 behind the rear panel.
PVC pipes carried water from a water tank using a water pump, with the used water being collected in a collection tray. The working pressure is 0.7 MPa with a maximum flow rate of 8 l/min.
The system was then installed on the roof of the University of Sharjah in the United Arab Emirates, at a fixed angle of inclination and at a height of 30 cm from the surface.
White paint was applied to the bottom surface to increase reflectivity.
Another identical reference system, also with a power output of 60 W, was installed on the same roof. The systems were then tested in three scenarios: sunny days without a mist cooler, sunny days with a mist cooler, and cloudy days with a mist cooler.
‘One of the most remarkable results was the significant increase in energy output we recorded,’ said Said.
In the extremely hot conditions typical of the United Arab Emirates climate, our sandwich bifaccial panels with mist cooling generated up to 37% more electricity on sunny days and up to 46% more on cloudy days than standard single-sided solar panels.
In addition, the temperature of the panels was significantly reduced – by up to 34% on the front side – which contributes significantly to this improvement in performance. According to the research team, the new system delivered an annual energy output 45.34 kWh/m2 higher than single-sided systems, corresponding to an annual economic gain of $5.48/m2.
Specifically, the expected annual production of the sbPV panel was calculated at 167.38 kWh/m2, compared to 122.04 kWh/m2 for the reference module.
"We plan to explore further improvements to this technology.
Future research will focus on integrating second-hand solar panels into the sandwich structure to improve sustainability and reduce environmental impact," Said added, noting that the proposed technique has been patented.
‘We will also investigate optimising the mist cooling mechanism to further reduce water and energy consumption, making it even more practical and environmentally friendly.’