Numerical Design Study for Desert Climate Applications of Bifacial PV Modules

Standard crystalline silicon solar modules have shown to be robust under moderate climate conditions but with the need for sustainable energy production, both the quantity of PV installations and the application in other climatic zones must be investigated. Due to the high annual amount of solar irradiation (2 to 3 times as much as in Central European climates), desert regions are actually ideal for solar applications in terms of potential energy yield. However, there are various challenges for the long-term reliability of the modules and components. In addition to well-known short-term effects, such as, soiling losses, the thermo-mechanical stress in desert regions is very challenging due to, from one hand, the higher ambient temperatures that could reach on average 40°C, while the module temperature could reach 70°C. From the other hand, the large temperature fluctuations between day and night that occur in desert climate induce thermo-mechanical stress. In parallel, a significant increase in cell size and thus change in module size is taking place. The long-established M2 wafer format is already being replaced by M6 and represents only a transition size to M10 and M12 wafers. In desert applications, bifacial cells have a particularly high potential for maximum utilization of the available irradiation due to the high albedo. In this paper, different cell sizes, cell spacings and cell connector thicknesses are analyzed and compared under thermo-mechanical loading using a finite element simulation. The aim is to find an optimum between the possible power gains by improving the cell to module (CTM) ratio, the area efficiency and module reliability in desert climate.