Feasibility of Using Phase Change Material Calcium Chloride Hexahydrate to Improve the Efficiency of Bifacial Photovoltaic Modules via Passive Cooling

It is well known that reducing the temperature of a PV cell improves its efficiency and increases its lifespan. Bifacial PV (bPV) currently makes up 30% of the market share of photovoltaic (PV) modules and is predicted to increase to 70% by 2033. Despite this trend, there has been little research into cooling bPV; this is because traditional methods involve placing a cooling system on the back of PV modules which would reduce the irradiance on the backside of a bPV panel negating the advantage of bPV. Therefore, to improve the operating temperatures of bPV, novel cooling strategies that do not obstruct irradiance on either panel side are required. This study investigates the feasibility of using calcium chloride hexahydrate as a transparent phase change material (PCM) to cool down the surface of a PV module. It was found that placing a 110g sample on top of a PV panel resulted in a maximum power increase of 9.5% and an energy gain of 5.3% over 45 minutes. When using a 160g sample, the maximum power increase was 10.7%, and 6.1% more energy was produced over a period of 52 minutes. However, the PCM systems increased the peak panel temperatures after phase change and thus were not suitable for use over extended periods of time. In future work, these temperatures could be reduced by redesigning the PCM container to improve the overall heat transfer coefficient, increasing the energy gain of the PCM systems. Overall, it has been demonstrated that the cooling effect of PCMs can outweigh the reduction in irradiance when placing them on the front of a PV panel, resulting in a net increase in power output, thus making them viable for cooling bPV.