Due to the constantly growing demand for electricity and the need to produce energy with limited CO2 emission, RES installations are being created, including photovoltaic farms. PV modules, using the phenomenon of photovoltaic effect, convert solar radiation energy into direct current, finally converted into alternating current. The generated current can be used to supply electrical equipment or it can be resold to the distribution network. In Poland, the most popular installations are designed up to 1MW. On almost 100 such facilities, modern e²TANGO protection relays were used, which implement protection functions, measurements and control for particular power plant.The produced electricity is supplied to the distribution network of almost all distribution companies in Poland – PGE, ENEA, ENERGA, TAURON, where in many 110/15 kV MV stations located throughout the country, universal and reliable e²TANGO protection relays were also used.