ACTA TECHNICA CORVINIENSIS - Bulletin of Engineering

1.CRISTIAN P. CHIONCEL, 2. DIETER KOHAKE, 3. LADISLAU AUGUSTINOV,4.PETRU CHIONCEL, 5 . GELU OVIDIU TIRIAN .YIELD FACTORS OF A PHOTOVOLTAIC PLANTAbstract:The paper gives the definition of the main yield factors that characterizes the performances of aphotovoltaic plant. This are analyzed for a grid connected photovoltaic plant at the University inResita, in use since spring 2008, were the main climatic and technique parameters of the photovoltaicplant are monitoriesed and heaped in an data base for further analysis.Keywords:yield factors, photovoltaic plant, photovoltaic systemINTRODUCTIONAccurate and consistent evaluations ofphotovoltaic (PV) system performance arecritical for the continuing development of thePV industry. These performance parametersallow the detection of operational problems;facilitate the comparison of systems that differwith respect to design, technology orgeographic locations.SPECIFIC YIELD FOR SOLAR PHOTOVOLTAICPLANTSParameters describing energy quantities for thePV system and its components have beenestablished by the International Energy Agency(IEA) Photovoltaic power System Program andare described in the IEC standard [1]. Thegenerally definition of yield factors of powerplants, expressed in simplified terms, describeshow many times energy generated during plantoperation covers the energy used forconstructing the plant. An exact definitionwould be: 'The yield factor is the ratio of netenergy production during plant life and thecumulative energy used for construction,operation and operating supply items'. Thisconcept is only meaningful in the context ofusing regenerative energy sources, asphotovoltaic plants, insular ore grid connected.Three of the IEC standard 61724 performanceparameters [2] may be used to define the overallsystem performance with respect to the energyproduction, solar resource and overall effect ofsystem losses. These parameters are theperformance ratio, final PV system yield andreference yield.The final PV system yield Y f is the net energyoutput E PV divided by the nameplate d.c powerP maxG,STC (STC – Standard Test Condition 1000W/m 2 , 25 0 C) of the installed PV array. Itrepresents the number of hours that the PV arraywould need to operate at its rated power toprovide the same energy. The units are hours orkWh/kW:AC − GridinjectedEnergyPR = (1)PVSystemEnergyInSTCThe Y f normalizes the energy produced withrespect to the system size, being a convenient© copyright FACULTY of ENGINEERING – HUNEDOARA, ROMANIA 63