Numerical Simulations of a PV Module with Phase Change Material (PV-PCM) under Variable Weather Conditions Stefano Aneli, Roberta Arena, Antonio Gagliano * University of Catania, DIEEI, Viale Andrea Doria, Catania 6-95125, Italy Corresponding Author Email: antonio.gagliano@unict.it https://doi.org/10.18280/ijht.390236 ABSTRACT Received: 1 April 2021 Accepted: 20 April 2021 The electrical efficiency of photovoltaic (PV) modules can be improved through the cooling of the PV. Among the passive cooling strategy, one of the most promising concerns the use of phase change materials (PCMs) to decrease the operative temperature of a PV panel. This paper investigates the performances of a conventional PV panel in which two organic PCMs are added (PV-PCM) to reduce the temperature rise of PV cells and consequently to increase the electrical performances. With this aim, unsteady numerical simulations have been carried with Ansys Fluent software using a two-dimensional simplified geometry for the PV modules with the PCM is incorporated (PV-PCM), as well as for the benchmark PV module. The numerical simulations have allowed evaluating the PV cell temperatures, the power production, as well the PCM thermal behavior. As regards this latter aspect the dynamic analysis has evidenced the need to extend the time of simulation at least for two days in such way to take into account of the degree of solidification achieved during the night by the PCM materials. PCM with low melting temperature cannot complete solidifying during the night and so the heat stored during the day will be lesser than the theoretical one. The results of this study pointed out that the PV-PCM units allow achieving higher performances in comparison with a conventional PV module, especially during the hottest months. An increase in the peak power of 10% and of 3.5% of the energy produced all year round is attained. Keywords: PCM, PV performances, cells temperature, CFD, simulation 1. INTRODUCTION The efficiency of PV cells is sturdily affected by the increase of their temperature, in fact, as the temperature of the cells increases, the energy yield decreases. Theoretically, the temperature coefficient γ, which relates PV efficiency and cell temperature, ranges from -0.4 to - 0.45% ℃. However, an experimental study has shown that this coefficient could rise to -0.65 % ℃ [1]. Furthermore, the PV panels heat up quickly as the layers have modes thermal inertia [2], so their efficiency decline as the solar irradiation grows. Table 1. PV cooling techniques Photovoltaic/Thermal hybrid solar system (PVT air /water cooling) PV/Phase-Change Materials (PV-PCM cooling) PV/Heat Pipes (HP-PV cooling) PV/Microchannel heat sink (PV-MCHS cooling) PV/Nano-fluids (PVT-NFs) PV/water spraying (jet impingement) PV/water immersion cooling Floating, tracking, concentrating and cooling (FTCC) PV/Spectrum filter (Beam Split PVT) PV/Transparent coating (photonic crystal) PV/Thermoelectric hybrid system (PV-TE cooling) Therefore, active and passive cooling techniques have been developed to cool photovoltaic panels to increase their efficiency [3, 4]. Active cooling techniques require the supply of energy, on the contrary, passive cooling does not require energy and also has lower maintenance requests. Table 1 enumerates the different solar photovoltaic systems cooling technologies as proposed by Lupul et al. [5]. Hybrid PV/Thermal collectors allow to optimize and control the PV cell temperature [6], increase the overall energy conversion efficiency [7], as well as diminish the need for installation space [8]. The performances of PV/T nanofluid for cooling the PV cells have been evaluated in the study [9]. Among the passive cooling strategy, one of the most promising concerns the use of phase change materials (PCMs) to decrease the operative temperature of a PV panel. PCMs act as a heat storage material where the thermal energy discharged by the cells is stored as latent heat of fusion, thus blocking the temperature increase. Hence these materials, whom temperature remains constant until the end of the melting process, allow for improved electrical conversion efficiency, creating a shift in temperature rise [10]. Therefore, the PCMs can accumulate thermal energy in the form of heat or cold with the possibility of using it later, this feature makes them extremely suitable for applications with electrical storages [11, 12]. International Journal of Heat and Technology Vol. 39, No. 2, April, 2021, pp. 643-652 Journal homepage: http://iieta.org/journals/ijht 643