Performance evaluation of grid connected photovoltaic systems

This paper presents investigation of design and performance of a real 3.9 kWp grid connected photovoltaic system installed on a flat roof of a laboratory building of Faculty of Electrical and Computer Engineering in Prishtina, Kosovo. This system consists of two types of photovoltaic modules, monocrystalline silicon and polycrystalline silicon, inverters, and devices for measurement and monitoring. The system was monitored between January 2014 and December 2015 and all the electricity generated was fed into the low voltage supply to the grid. During the monitoring period daily and monthly parameters of photovoltaic system are measured and analyzed. These include parameters such as: power generation, daily solar radiation, air temperature, photovoltaic module temperature and wind speed. The results of photovoltaic monthly average parameters such as: final yield, reference yield and performance ratio are presented and analysed.