This study investigate the conditions for the initiation of lightning upward connecting leaders (UCL) in large-area photovoltaic (PV) plants to enable the assessment of the most likely strike points on the PV array. The methodology, based on the Charge Simulation Method (CSM), is implemented in MATLAB, considering in-depth studies on lightning physics to describe the mechanism of the lightning strike with the necessary assumptions to simplify while maintaining a physically consistent model. The evaluation of possible UCL inception in the PV array is conducted by analyzing the electric field in the vicinity of the PV panels, a necessary condition for the formation of streamer corona discharges at the edges of the PV panels. To compare with a situation prior the erection of the PV plant, the analysis is also performed to the flat ground. In order to validate the results obtained with the implementation of the CSM, simulations based on the Finite Element Method (FEM) are performed to evaluate the electric field levels in the vicinity of the conductors, overcoming some limitations of the CSM due to the effect of proximity. With the support of the software Ansys Maxwell as a user-friendly interface for the FEM approach, the electric field at the leader tip and on the PV array structure is evaluated more consistently and the results are similar to those obtained by applying the CSM. In summary, this evaluation provides insights for studies on safeguarding large-area PV systems against lightning strikes, thereby advancing external lightning protection strategies in renewable energy infrastructure.