Bifacial Photovoltaic Systems Energy Yield Modelling

A bifacial photovoltaic model was developed not only to calculate the power and energy yield for bifacial modules for various setup and installation conditions but also to identify suitable bifacial module applications and markets. The bifacial model shows that the energy yield for bifacial modules is very much location dependent and hugely influenced by how they are setup and installed. There is a need to have the modules mounted at a certain elevation above the ground to gain maximum energy yield. It is also important to ensure there is no blockage for the direct sun to shine on the area directly beneath the module. For locations at low latitude, a higher elevation is required. For locations at high latitude, the probability of the direct sunlight reaching the ground directly under the module is higher. Therefore, less module mounting elevation is required. However, there is a saturation point for energy yield improvement with increased module mounting height. In addition to the mounting height, a sufficient length of clearance path in front of the module array should be considered. The model also shows that the ground reflectance is one of the key parameters for bifacial module performance. The model indicates that >10% of energy yield gain with 20% background reflectance from REC bifacial multi-crystalline silicon solar module array with a bifaciality of 0.6 is achievable in Konstanz, Germany. This correlates well with the measured field energy yield data of the bifacial prototype modules.