Cooling of a PVT System Using an Underground Heat Exchanger: An Experimental Study

In the recent decades,the researchers have been focused on theuse of photovoltaic thermal (PVT) systems that provide the best performanceand cooling for the photovoltaic panels. In this study, a PVT systemconsisting of a monocrystalline PV panel and a spiral heat exchangerwas connected to an underground heat exchanger that is buried at adepth of 4 m below the surface of the earth. The procedure of thecurrent study can be considered the first of its kind in the MiddleEast and North Africa region (based on the researchers' knowledge).The study was carried out on agricultural land in Baghdad-Iraq duringmonths of July and August-2022, which are considered the harshestweather conditions for this city. The heat exchanger consists of acopper tube with a length of 21 m and formed in the shape of 3U, andit was buried in the earth and connected with a PVT system. The resultsof the study showed that the site chosen to bury the heat exchanger(4 m deep) has a stable soil temperature at 22.5 & DEG;C. From variousvolumetric flow rates, a flow rate of 0.18 l/s was selected whichis considered the highest flow rate that can show vibration in thePVT system which may harm the system. The practical measurements showedthat the largest difference in the surface temperatures of standalonePV and PVT was around 20 & DEG;C in favor of the latter. The electricalefficiency of the studied PVT system also increased to outperformthe standalone PV system by 127.3%. By comparing the results of thecurrent study with studies of water-cooled PVT systems from the literature,it is clear that the proposed system is feasible and has an acceptableefficiency in such harsh weather conditions tested during the experiment.