Cooling Photovoltaic Cells by Phase Change Material (paraffin wax): Obstacles and Solutions.

The efficiency of crystalline silicon-based PV cells decreases with increase in operating temperature so this work studies the performance and effectiveness of PV cell cooling using PCM (paraffin wax). It is clear that the cooling with paraffin wax suffers from limitations, namely the melting point and the low thermal conductivity of the wax. The main objectives of the study are: determine the optimal layer thickness of PCM, the presence or absence of fins and their number. The research includes the analytical model and practical experiments. Data were collected from 9:00 a.m. to 4:00 p.m. The experiment consists of three models; The first one is without cooling for comparison. The second is a cooler with an aluminium tank containing wax and without fins, placed on the back of the cell. The third includes 12 fins inside the wax. The results of the second model showed low cooling efficiency due to poor thermal conductivity, in addition to excessive heat after midday. In the third model, poor thermal conductivity was addressed and cooling efficiency increased, but the problem of wax overheating became worse after midday, deteriorating cell efficiency. The modelling was created and analyzed using SOLIDWORKS, ANSYS, and MATLAB, several models were proposed in this part, the first three of which were identical to the practical experience, and the results showed the same limitations and obstacles. Regarding other models, it has been noted that when the wax layer is 5 cm thick, adding more internal fins improves the conduction thermal efficiency, and also leads to an exacerbation of rise in the temperature of the wax after midday. The models when the wax layer is 7 cm thick. The efficiency increased for a longer time than the 5 cm thickness. When 12 and 24 internal fins were added to the 7 cm thick wax layer, the efficiency increased more than the layer 5 cm thick with less overheating in the cell afternoon. Added 12 and 24 internal and external fins reducing the wax temperature in afternoon much less than the decrease in cell efficiency before noon because of the external fins. Increasing the thickness of wax to cover cell working time and adding certain number of internal fins that increase the thermal conductivity is the best model.