Researchers are increasingly focusing on free space optical (FSO) communication as a high-speed wireless communication solution for both backhaul and fronthaul networks in 5G and future 5G + systems. Also, unmanned Aerial Vehicles (UAVs) or drones are becoming popular for various applications, such as surveillance, monitoring, imaging, and data collection. These UAVs are required to have a longer flight time to ensure the sustainability of the communication system over long distances. Therefore, energy harvesting in an FSO-UAV-based communication system using simultaneous lightwave information and power transfer (SLIPT) is proposed in this manuscript. For this study, simulations were carried out for various cloud models, beam divergence, and zenith angles. The energy harvested from photo voltaic (PV) solar panels integrated into drones is determined across different altitudes and various FSO link design parameters. It is found that under clear sky conditions, the system can harvest up to 1 mW of power at a UAV altitude of 150 m, regardless of the zenith angle. A significant drop in the harvested energy is observed as the beam divergence increases from 1 to 3 mrad for all cloud models. Further, it is observed that the configuration of the FSO system particularly in terms of beam divergence, link length, and zenith angle plays a critical role in energy harvesting when operating under diverse cloud models. These results emphasize the significance of customizing FSO link design parameters to adapt to different atmospheric conditions, with a specific focus on cloud cover, in order to maximize both energy generation and overall system performance.