# Lightning Protection of Photovoltaic Systems: Computation of the Developed Potentials
In [5], the necessity of a risk management analysis according to the International Standards, and the importance of an extensive study of lightning protection systems are highlighted in order to apply appropriate protection measures against external surges. Considering that inadequate protection against lightning phenomena can delay the investment return of the PV system, it is highly recommended to take into account techno-economically balanced protection measures. Indeed, the design and implementation of an efficient LPS are of great importance for the secure operation of PV installations, of which the capital investments are significant. In fact, as it is highlighted in [5], the cost of installing an LPS may be proven insignificant when compared to the revenue losses incurred due to damages in case of a lightning strike. The amplitude and the steepness of the lightning current, the characteristics of the LPS, the soil resistivity of the installation area and the geometrical and electrical characteristics of the grounding system are critical factors that influence the lightning protection of the PVs. In [5], some of the aforementioned design parameters of an LPS on large-scale PV plants are studied, but without an in-depth review of the impact of multi-layer soil structures on the developed potential in case of a lightning strike. Research, as described in a recent review on the performance of lightning protection on photovoltaic systems (roof mounted or solar farms) has just started due to high penetration on the power distribution grids [6]. In [4], the impact of a standard impulse lightning strike on the performance of single PV modules is evaluated. The impact of distributed generation on the lightning protection of distribution lines is examined in [7; 8; 9]. Case studies are described in [10] regarding the performance of an LPS on a Greek hybrid power network and in [11; 12] regarding the effects of a lightning strike on different parts (AC or DC) of a PV park in Malaysia. Moreover, in [13], a solar grid-connected PV module without LPS is modeled and simulations are performed under various scenarios, in order to assess its lightning performance and to highlight the importance of an LPS. In [14], a new computer algorithm is presented that can be used to evaluate the risk of damage in PV systems and the need for installation of a lightning rod. Analysis of touch potentials in solar farms and recommendations to reduce them are presented in [15] and the effect of group grounding on the potential rise across a solar farm during a lightning strike is simulated with the PSPICE software tool in [16]. Finally, in [17], PV generation connected to high-voltage generation and its impact on the proper operation of the protection systems of the power grid is studied. In [18], the design of the grounding system on a hybrid power station (wind, PV, energy storage) is studied considering the soil structure. In this paper, the developed potential caused by lightning surges in a 100 kWp PV system are estimated by using an appropriate simulation software. This is a particularly advantageous approach as it enables the evaluation of three lightning protection systems' setups, i.e., an attached, a non-attached, and a modified non-attached lightning protection system, considering different soil structures and characteristics of the grounding system. In addition, the impact of the perimeter grounding and the grounding electrode length on the developed potential are investigated in this work. Finally, in the case of a non-attached and a modified non-attached system, simulation results are presented for a variable distance between the lightning rod and the metallic structure of the installation, as well as for different types of insulators.