A novel thermal regulation method for PV panels as buildings' facade using oil natural, air natural system

Building facades exhibit a particularly attractive platform for vertical photovoltaic (PV) panel deployment due to their large surface area, consistent solar energy capture throughout the day, and their contribution to reducing the building cooling loads. However, elevated operating temperatures negatively impact the electrical performance and overall efficiency of PV panels. Unlike the existing PV cooling technologies, the present study proposes, for the first time, a completely passive method based on the concept of Oil-Natural, Air-Natural (ONAN), employed in electrical distribution transformers. The ONAN approach is modified in the context of vertically mounted PV modules installed on facades on the back side of PV panels, using two fluids: water and low-viscosity silicone oil (5-cSt). The test results showed that the water-based system has the capability to reduce the temperature of the PV panel by 10.84%, which caused an increase in the electrical efficiency by 18.17%. The silicone oil-based system led to only 4.63% decrease in panel temperature and 8.51% increase in electrical efficiency. The superior thermal properties of water resulted in higher power output compared to oil. Silicone oil, though, is much more stable over time; it will not corrode metal pipes or oxidize and it evaporates much slower than water. These results indicate that transformer-inspired passive cooling is a viable, energy-free, maintenance-free technique for improving the electrical performance of facade-integrated PV systems.