The temperature distribution across the photovoltaic (PV) module in most cases is not uniform, leading to regions of hotspots. The cells in these regions perform less efficiently, leading to an overall lower PV module efficiency. They can also be permanently damaged due to high thermal stresses. To enable the high-efficiency operation and a longer lifetime of the PV module, the temperatures must not fluctuate wildly across the PV module. In this study, a custom absorber is designed based on literature to provide a more even temperature distribution across the PV module. This design is two standard sets of spiral absorbers connected. This design is relatively less complicated for this reason and it allows room for adjusting the pipe spacing without much complication. The absorber design is tested via computational fluid dynamics (CFD) simulation using ANSYS Fluent 19.2, and the simulation model is validated by an experimental study with the highest percentage error of 9.44%. The custom and the serpentine absorber utilized in the experiment are simulated under the same operating conditions having water as the working fluid. The custom absorber design is found to have a more uniform temperature distribution on more areas of the PV module as compared to the absorber design utilized in the experiment, which leads to a lower average surface temperature of the PV module. This results in an increase in thermal and electrical efficiency of the PV module by 3.21% and 0.65%, respectively.

In the study, the photovoltaic thermal system using nanofluid as coolant is validated using numerical approach by comparing the experimental results and simulation results. Due to high cost and difficulty in preparing nanofluid, it is more practical to perform the study using numerical approach which is convenient and saves plenty of time. The photovoltaic thermal system is investigated numerically through Computational Fluid Dynamics Approach using Ansys 19.0 Fluent Software. The numerical study is based on different solar irradiation at different hours. The coolant that is selected in the study is aluminum oxide () water nanofluid. The validation study between the experimental results and simulation results are achieved by examining the photovoltaic (PV) surface temperature and nanofluid outlet temperature. The maximum percentage of error between experimental and simulation results of PV surface temperature and nanofluid outlet temperature are 12.66% and 7.89%. Also, the mean average percentage error (MAPE) are computed for PV surface temperature and nanofluid outlet temperature. The results for PV surface temperature and nanofluid outlet temperature are 10.31% and 6.67%. Since the MAPE results are within 10% or error, it proved that there is good accuracy between the simulation and experimental results.

Although, the effect of mass flow rate and solar irradiance variation is present in literature, it is still of significant interest to investigate the extent of the effect especially when utilizing a custom absorber design. In this paper, the effect of changing the mass flow rate and solar irradiance on the performance and temperature uniformity of a PVT using a custom spiral absorber design is simulated using ANSYS CFD software. By increasing the mass flow rate, the temperature uniformity and the performance parameters such as the average PV temperature, water outlet temperature, thermal and electrical efficiency all increase. By increasing the irradiance level, performance and temperature uniformity drop albeit at a smaller degree compared to change observed in mass flow rate variation. Amongst the tested range, the optimum mass flow rate and solar irradiance levels for best performance are 40 kg/h and 800 – 1000 , respectively.

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