Performance Analysis of 3.9 kW Grid Connected Photovoltaic Systems in Kosova Vjollca Komoni, Isuf Krasniqi, Arben Lekaj, Ilir Gashi University of Prishtina “Hasan Prishtina”, Faculty of Electrical and Computer Engineering Prishtine, Kosovo vjollca.komoni@uni-pr.edu Abstract— This paper presents results obtained from monitoring a 3.9 kW p grid connected photovoltaic system installed on a flat roof of a laboratory building of FECE in Prishtina, Kosovo (Latitude 42.6667°N and longitude 21.1667°E ). System was monitored between the May 2013 to November 2013, and all the electricity generated was fed into the low voltage network supply to the building. This system consists of two types of photovoltaic modules, monocrystalline and polycristalline, inverter, and devices for measurement and monitoring. During this period are measured and analyzed daily and monthly parameters of system, such as: power generation, daily solar radiation, air temperature, PV module temperature and wind speed. Monthly average daily performance parameters of the PV systems evaluated include: final yield, reference yield, system efficiency, and performance ratio and capacity factor. These results will be enabling to evaluation and used the photovoltaic systems in Kosovo climatic conditions. Keywords: Photovoltaics, Grid connected, Final yield, Performance ratio. I. INTRODUCTION Electricity produced in Kosovo up to 96% is produced from lignite, and therefore energy production strategy must take into account the production of electricity from renewable sources, according to Directive 2009/28/EC of the European Parliament. In order to reduce the producer of conventional coal energy sources and serious Environmental problems, we must develop variable renewable supply. Electricity generation using photovoltaic (PV) systems is important, reliable and has the potential to play a significant role in CO 2 emission mitigation [3]. It is widely accepted that PV will became one of the major future sources of electricity generation considering the potential for cost reduction of PV systems and grid-parity expected Southern and Northern Europe around 2020 [4]. Total global installed capacity of grid connected PV systems was 15 GW, 22 GW, 38 GW, in 2008, 2009 and 2010 respectively. Around the world 31.1 GW of PV systems were installed in 2012, up from 30.4 GW in 2011; PV systems remains, after hydro and wind power, the third most important renewable energy source in terms of globally installed capacity. 17.2 GW of PV capacity were connected to the grid 978-1-4799-2195-9/14/$31.00 ©2014 IEEE in Europe in 2012, compared to 22.4 GW in 2011; Europe still accounts for the predominant share of the global PV market, with 55% of all new capacity in 2012 [4]. The aim of this paper is to present results obtained from measured performance monitoring of a 3.9 kW p PV systems installed in Prishtina, Kosovo. The different performance evaluation parameters are presented based on collected data between May 2013 and November 2013. The performance parameters calculated include: monthly energy generated, final yield, reference yield, performance ratio, the average ambient air and PV module temperature against different levels of solar radiation. Performance dates are compared with those obtained in other locations in Europe and Middle East. II. THE PV SYSTEM The PV system was installed on the roof of Laboratory buildings at the Faculty of Electrical and Computer Engineering in Prishtina, Kosovo. The roof is approximately 8 m high and the modules were fixed mounted at an angle of 45 0 , and are facing south. Such a tilt angle was chosen to maximize yearly energy production, taking into account the geographical position of Prishtina. The installed capacity of 3.9 kW p , grid connected systems consisted of 18 modules, with an active surface area of 26.26 m 2 . The systems is consist of 9 PolySol 240 VM (IBC Solar, STC Power 240 Wp, module efficiency 14.7%) polycrystalline silicon modules, and 9 MonoSol 195 DS (IBC Solar, STC Power 195 Wp, module efficiency 15.3%) monocrystalline silicon modules. The PV modules are arranged in 2 branches with 9 modules in each, and connected to Sunny Boy SB 2000 inverters installed, irradiance and temperature measurement instrumentation and data logging systems (Sunny Sensorbox and Sunny WebBox). The single phase inverters are tied in electrical installation of buildings. The inverter had a rated maximum efficiency of 95 % and maximum AC power of 2000W. The solar irradiation sensor had measurement range 0 W/m 2 to 1500 W/m 2 , measurement accuracy  and a resolution 1 W/m 2 . The PV module temperature sensor was a platinum sensor PT 100