Passive Cooling of Photovoltaic Modules in Qatar by Utilizing PCM-Matrix Absorbers
Abstract
Operation of solar PV systems under extremely high temperatures and high humidity in hot climates represents one of the major challenges to guarantee higher system’s reliability. Therefore, thermal management in hot climates is crucial for reliable application of PV systems, as it has a potential to increase the efficiency and life expectancy and to stabilize the output power characteristics. On the other side, dust accumulation on PV module together with atmospheric water vapor condensation may cause a thick layer of mud that is difficult to be removed. The present research focuses on utilization of Phase Change Materials (PCM) for passive thermal management of solar systems. Passive cooling uses the high temperature differences between day and night in arid desert regions, due to sky radiation in the night. The high thermal capacity of PCM accumulates coolness during night to keep the PV cells at a moderate temperature during the day. This also can help maintaining the PV panel temperature well above the dew point to prevent condensation during day and night, thereby avoiding mud formation on the panel surface, which reduces water consumption and mechanical efforts in cleaning. The numerical simulation results showed that there are optimum thermos-physical properties for PCM Absorbers for cooling of PV modules under Qatar weather conditions. It has been concluded that the ideal PCM-Absorber should have a melting temperatures of 53-54 °C, 30 mm PCM thickness, and 85 % fiber porosity of metallic aluminum fiber structure and with aluminum heat fins. With the optimum design of PCM-Absorber, the PV module’s peak temperature can be reduced by 23°C during daytime and at night it can be maintained at 3-5 °C higher than conventional modules, which reduces water vapor condensation tendency. Furthermore, depending on the temperature coefficient of a PV module, the power production can be increased by up to 9-11% for mono and poly crystalline cells respectively, and up to 8% for thin film technology. The module’s instantaneous efficiency can be increased by 1-2%. A techno-economic analysis for commercial scale application of the proposed thermal management solution has also revealed promising results, especially under the optimized design conditions and local manufacturing in Qatar utilizing oil waste, which makes it economically viable.