Exploratory data analysis of lightning location and return-stroke parameters at photovoltaic power plant sites

This study presents an Exploratory Data Analysis (EDA) of cloud-to-ground (CG) lightning location data from the ALDIS/BLIDS system for 60 ground-mounted photovoltaic (PV) power plants in Germany, covering an observation period from 2005 to 2025. To ensure temporal consistency across this extended dataset, which spans a period of known changes in network performance, a simplified time-based correction factor (CF) was introduced. The CF normalizes annual stroke densities in local reference areas to the stable post-2022 network state. Both negative and positive CG lightning strokes were analyzed, covering event counts and return-stroke peak current amplitudes over five-year periods before and after PV plant installation. Lightning activity within capture areas (CA) encompassing each plant was compared with corresponding local reference areas (RA). A size stratification analysis examines whether plant area modulates the observed response, and a case study compares the local lightning density around a PV plant with that around a tall structure. Across all analyses, no systematic influence of PV plant installation on local lightning frequency or peak current amplitude was detected. The findings also support the use of site-specific lightning data, rather than generalized regional density maps, for the planning and optimization of lightning protection systems at large-scale PV installations.