An experimental investigation on passive cooling of the photovoltaic panel using CuO nanofluid in a two-phase closed thermosyphon

The main goal of the study is to increase the photovoltaic (PV) panel's efficiency by applying the two-phase closed thermosyphon system having CuO nanofluid, which is a heat pipe-supported passive cooling method, to photovoltaic (PV) panels. For this purpose, in addition to the selected reference panel (PV1), five different passive cooling designs were performed, and experimental studies were carried out. In the first design, deionised water alone (PV2) and in the second design, passive cooling was applied by immersing the pure water heat pipes in deionised water (PV3). In the third, fourth and fifth designs, passive cooling was achieved by immersing 1 mass%, 2 mass% and 3 mass% (PV4, PV5 and PV6) CuO/pure water nanofluid heat pipes in deionised water, respectively. Experiments were conducted using a solar radiation source created with an incandescent lamp under laboratory conditions. The changes in the efficiency of the newly designed panels with five different passive cooling systems compared to the reference panel (PV1) were evaluated with both experimental results and theoretical calculations. As a result of these comparisons, it has been determined that passive cooling with heat pipes with CuO nanofluid is effective in increasing efficiency by decreasing the panel's front surface temperatures. The panel's front surface temperatures were 67.7 & DEG;C in PV1, while 55.2 & DEG;C, 51.8 & DEG;C, 51.4 & DEG;C, 51.7 & DEG;C and 50.9 & DEG;C in PV2, PV3, PV4, PV5 and PV6, respectively. Consequently, the highest increase in the efficiency of PV1 was realised in PV5 with approximately 7%.