I chose the designing of a earthing system of a solar power plant for the topic of my thesis. During the choosing the topic I would have liked to examine lifelike problem which is apliable in the life of work. I got an insight into the base of designing work, so I gained useful experiences. I got help from József Ladányi Dr. and János Rejtő, who is an experienced engineer. They provide data which were the base of my work. On the following pages the reader can gain informations about designing of an earthing system of a solar power plant. The initial data and the results of calculation will be exhibited then they will be shown in an unity beacause of the better managing and better comparing. The study will examine all the closures, which have biggest draining effect of the electric network in details. With all the effects of the different closures on the network has to guarantee the safety of the individuals in the area. The calibration of the grounding system depends on the strain which apply the calibration of the closure due to the safety of the individuals and values. In the knowing of the flows of the grounding closure we could calibrate the earthing system. A possibly occurance of an earthing closures may cause earth potential rise. I could determine this occurence with CDGES software. I examined the touch and step voltages in the area. The touch and step voltages which are at most allowed on the individuals are encrypted in the MSZE EN 50522:2011 standard. The counter of the closure time is a meaningful factor in the allowed touch voltages point of a view, so it’s value depend on the protection devices of the network. The knowing of the flows of the earthing closure I settle a minimal cross section, which is efficient for the performance of the earthing system.