A simulation procedure to predict the monthly energy supplied by grid connected PV systems

Within the Italian solar-roof program, a 1.5 kWp system and a 1.9 kWp system have been installed at Politecnico di Torino and at Bologna University. The paper presents a simulation procedure, based on daily profiles of irradiance and temperature, to calculate the energy production of grid connected PV systems. Profiles of irradiance are identified by a shape factor which determines sharp or flat diagrams with respect to the sinusoidal one. Simulation procedure consists of three blocks: the first contains the model of irradiance and temperature, the second the PV array equivalent circuit and the third the efficiency of inverter. Parameters of simulation are adjusted by experimental results from the two PV systems. Twelve profiles of daily irradiance and array temperature, monthly mean values, provide the PV yearly energy. The monthly mean days allow the assessment of yearly AC energy with a deviation of 3.5% as regards the experimental values.