Energy Yields of PV Systems - Comparison of Simulation and Reality

Simulation of PV systems is an important feature to predict mainly the yield but also the operational behav-iour. How accurate are the simulation results? Thus the purpose of the work is to demonstrate the differences between simu-lation and reality. In a first step, three 1 kWP PV systems coming from the solar promotion “Sun at School” have been inves-tigated. Measured yields were available for many years. The software tools PVSYST and PVSOL have been applied to simu-late the systems. In a second step, the yields of the 1016 kWP PV system on the New Trade Fair Centre in Munich – which went in operation in 1997 - has been simulated using the block oriented simulation system INSEL. Simulation of two cases on the basis of measured irradiance data in the generator plane and ambient temperature data are leading to best simulation results. The total annual deviation between simulation and measurement is +5,2 % in case of the fit with measured module data and -1,4% for the data sheet case. Of course, this does not mean that the data sheet approach is more accurate since cable losses, mismatch losses etc. have not been considered at all.