Renewable energy capacity show global tremendous increase in the last decade. Photovoltaic technology continues to expands its leadership role surpassed the impressive 300 GW installed electrical power in 2016. Large, ground-mounted PV plants are usually located in lands far from cities. In the urban environment, rooftop PV system is a widespread option for generating electrical power due to a large amount of empty rooftop spaces that avoid the potential land use and environmental concerns. Despite the fact that PV systems usually require low maintenance, they are still subject to various failures modes. Failure Modes and Effect Analysis (FMEA) is a technique for the analysis of a system reliability identifying the potential failure modes, their causes and effects on system performance and overall safety. The work presents this methodology applied to a grid-connected rooftop PV system located in an urban area of Serbia’s capital, Belgrade.