Estimation of the average annual number of lightning flashes to a group of wind turbines in France

The evolution of the local lightning density observed before and after the construction of a group of wind farms installed in a mountainous region of France is analyzed using an 18-year period lightning data. Considering the effect of the limited upward lightning detection efficiency of the lightning locating system on the data, the enhancement factor is estimated to be 3.9 times the natural lightning density before the construction. This result is half the correction factor suggested by the IEC61400-24:2019 methodology, but because it is based on conservative assumptions and high-resolution lightning observations it is considered realistic. Finally, this study also brought some materials and comments on the methodology proposed in the standard guidelines.