Influence of inverter control logics on energetic performances of PV modules - inverter systems

The Maximum Power Point Tracking logic which regulates inverters in PV plants plays a fundamental role in order to obtain maximum power from PV modules array, despite of fluctuations of modules temperature and irradiance, both in grid connected and stand alone systems. Due to these fluctuations there is a continue variation of module electric performance. and so the inverter has to realize circuit condition which maximize PV plant power for that irradiance and modules temperature. A regulation system which doesn't fully optimize this situation, leads to an energy output certainly lower than declared; starting from commercial modules data sheets, in this work an evaluation of missing energy production has been performed, considering that power curve of PV modules decreases rapidly around its maximum point. Giving a gaussian distribution of regulation system mismatching, missing energy production has been evaluated vs different values of solar irradiance and corresponding functional parameters of PV module. Considering not negligible effect of module operating temperature, the missing power due to this factor has been evaluated too, considering that usually inverter regulation system doesn't neglects this operational parameter an woks considering module in standard temperature condition. Result are presented in a series of diagrams which allow a technical and economic evaluation of an hypothetic upgrade of inverter regulation system which would take into account all these fluctuations.